CA2046274A1 - Method for planning radio cells - Google Patents
Method for planning radio cellsInfo
- Publication number
- CA2046274A1 CA2046274A1 CA2046274A CA2046274A CA2046274A1 CA 2046274 A1 CA2046274 A1 CA 2046274A1 CA 2046274 A CA2046274 A CA 2046274A CA 2046274 A CA2046274 A CA 2046274A CA 2046274 A1 CA2046274 A1 CA 2046274A1
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- Canada
- Prior art keywords
- matrix
- cells
- interference
- coverage
- mobile unit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000011159 matrix material Substances 0.000 claims abstract description 98
- 230000007717 exclusion Effects 0.000 claims abstract description 39
- 238000005259 measurement Methods 0.000 claims abstract description 24
- 238000004422 calculation algorithm Methods 0.000 claims abstract description 13
- 230000003993 interaction Effects 0.000 claims abstract description 8
- 230000000903 blocking effect Effects 0.000 claims abstract description 6
- 230000002452 interceptive effect Effects 0.000 claims description 11
- 238000005315 distribution function Methods 0.000 claims description 4
- 238000013179 statistical model Methods 0.000 claims 1
- 230000006978 adaptation Effects 0.000 abstract description 3
- 238000013461 design Methods 0.000 abstract description 2
- 238000013468 resource allocation Methods 0.000 description 3
- 238000000342 Monte Carlo simulation Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
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- 241000270276 Natrix Species 0.000 description 1
- BBRBUTFBTUFFBU-LHACABTQSA-N Ornoprostil Chemical compound CCCC[C@H](C)C[C@H](O)\C=C\[C@H]1[C@H](O)CC(=O)[C@@H]1CC(=O)CCCCC(=O)OC BBRBUTFBTUFFBU-LHACABTQSA-N 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/18—Network planning tools
Abstract
(57) Abstract The present invention relates to a method for planning radio cells. The method utilizes an exclusion matrix calculated on the basis of measured field strengths and an iterative allocating algorithm, which allows an adaptation of the cell planning to pre-vailing traffic demand. The method includes the following steps: the traffic demand is geographically estimated; an acceptable coverage of the traffic demand is produced with the aid of a number of cells with suitable transmitter powers and antenna ar-rangements; each cell is allocated a number of channels, which corresponds to the estimated traffic demand, having regard to a margin for acceptable blocking; coverage and interference measurements are carried out for the cells, which measurement results are stored in a measurement data base; an exclusion matrix is calculated on the basis of the measurement results, which matrix represents the interaction between the cells in the system; an allocating algorithm is iterated, which algorithm, by utilizing a ran-dom technique, provides different collections of channel allocations for the cells; if the channel allocation is not possible with re-gard to the number of channels in a given frequency band, a new attempt is made and the subsequent steps are repeated; if the number of channels was sufficiently high, a radio cell design is obtained which is acceptable from the point of view of interfer-ence and the point of view of blocking. The present invention also provides a method for constructing the exclusion matrix and a method for determining uplink interferences.
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Description
~vo 90/l0342 1 ~ 2 7 ~ PCT/SE90/00130 METHOD FOR PL.~NNING RAGIO CELLS
FIELD OF THE INVENTION
The present invention relates to a method for planning radio --rells, particularly planning cells with control over the interaction between the cells in the system and the capability of channel allocations which vary in accordance with the traffic demand. The method utilizes field strength measurements and an allocating algorithm, which permit a simple adaptation of the cell system~ that is to say increasing or decreasing the number of cells with altered traffic demand. In particular, the invention relates to the planning of mobile radio cells. The changes in the traffic demand can relate to diurnal variations in the traffic and more long-term variations due to changes in the route network and so forth.
The present invention also relates to a method for constructing an exclusion matrix for resource allocation in a radio system. The radio system can be unidirectional with communication in only one direction, for example a paging system, or bidirectional, for example a mobile radio system. In the application, a mobile radio system is preferably considered, but it is understood that the Z5 invention is aLso applicable to a unidirectional system. In a mob;le radio system, it is of importance that the available frequence resources are used in such a manner that the system caPaCity is optimized under the condition that the customers obtain an acceptable quality. In a microcell system in a densely populated area, ;t is des;rable that the channel allocation can be ta;lored to the actual traffic d;stribution. Such planning ;s a very demanding task and there are great sains to be made if the operator of the system has full control over the inherent interferences in the system. An improved quality and traffic handling in a given frequency range is, moreover, equivalent to an increased frequency economy.
The follow;ng prerequisites are given: a distribution of , .
.
:
-, WQ 90/10342 2 ~ ~ ~ 2 ~ ~PCT/SE90/00130 traffic demand over, for example, Stockholm, system parameters which define which C/I ~carrier to interference) interference ratio is required for good reception and how much interference a receiver tolerates in adjoining channels, and a frequency band for the system with a limited number of channels. It is the object to distr;bute the channels to the different base stations in the given frequency range so that the quality of connection experienced by the customers satisfies the given minimum requirements.
The present invention further relates to a method for determining uplink interferences in a mobi(e radio system, that is to say determining the degree of interference in a cell with respect to interfering mobile units in another cell.
STATE OF THE ART
Earlier mobile radio cell planning methods were static methods, that is to say all cells are always operating with one and the same channel allocation. Since direct f;eld strength measurements have not been utilized previously, there has been no check of the factual interference ratios and it has been diff;cult to make new channel allocations. It is an uneconomical utilization of the resources for all cells to be operating at all times.
According to the first aspect of the ;nvention, there is complete control over the interference ratios, that ;s to say the interaction in the system, at all times. The invention thus offers a method which provides for simple adaptation to the prevailing traffic demand.
In the art, the problem of resource allocat;on has been solved ; essentially as follows: a systematic descr;pt;on is g;ven of all the restr;ct;ons which apply to channel d;str;but;on ;n the form of a so-called exclus;on matrix. An exclusion matrix provides a description in symbol;c form of how different base stat;ons, or alternat;vely mobile un;ts in d;fferent coverage areas, can coexist with respect to the same channel and with respect to the adjacent channel. Then allocation algorithms are used for finding exactly which channels the different base stations should have for the 35 minimum requirements for the connection quality to be satisfied. The -method is used little since it is difficult to character;ze a large city with respect to wave propagation ;n such a manner that a useful ~ , , . . . :. .
. :. . . . ~ . , :
YyO 90/10342 ~ ~ ~ 5 h 7 ~ P ~ /SE90/00130 field strength and interference field strengths can be predicted within a few d~ at relevant points, for example along the main traffic routes~ There are examples of attempts made with large prediction programs based on terrain models. In reality, however, there is no possibility of putting in information about how, for example, all antenna patterns look with their in reality extremely irregular patterns. Such attempts thus have a tendency to create completely unrealistic calculat;on volumes.
According to the second aspect of the invention, basically 1û simple and completely realistic methods are used for providing the wave propagation information which is suitable for calculating an exclusion matrix~ for example for Stocholm. The exclusion matrix in turn makes it possible to run an allocation program, and channel allocations are obtained for a situation with very well known and desired interference ratios which ensure a good communication quality.
When determin;ng degrees of interference in mobile radio systems, only the downlink interferences have previously been considered, that is to say disturbances from base stations in other cells. It has been assumed that this is sufficient, especially since there has not been any method for characterizing interference from the moving mobile units in other cells. However, it has been shown that there can be a significant difference between the downlink and uplink interferences. Normally, the degree of interference is greater ;n the uplink situation than in the downlink situation. This implies that a resource allocation can be constructed which has an acceptable degree of downlink interference but too h;gh a degree of uplink ;nterference, wh;ch naturally ;mplies that the system is unacceptable overall.
According to the third aspect of the present invention, it is now possible to determine in an effective way the degree of interference for the uplink case so that th;s problem can be remedied.
SUMMARY OF THE INVENTION
According to the invent;on, a method for planning radio cells is provided, according to which:
the traffic demand is estimated geograph;cally;
., .
'~
.~ .
- . . . - . . -W O 90/l0342 ~ 2 7 ~ PCT/SE90/00130 an acceptabte coverage of the traffic demand i5 produced with the aid of a number of cells with suitable transmitter powers and antenna arrangements;
coverage and interference measurements are carried out for the cells, which measurement results are stored in a measurement data base;
each cell is allocated a number of channels which corresponds to the estimated traffic demand having regard to a margin for acceptable blocking;
1û an exclusion matrix is calculated on the bas;s of the ~ measurement results, which matr;x represents the interaction between the cells in the system;
an allocating algorithm is iterated, which algorithm, by - utilizing a random technique, provides different sets of channet aLlocations for the cells;
;f ;t is not poss;ble to allocate channels with respect to the maximum number of channels, a new attempt is made, and an acceptable radio cell design is obtained if the channel number was sufficiently high.
The present invention also provides a method for constructing the above exclusion matrix for optimum channel allocation.
The present ;nvention further prov;des a method for determining upl;nk interferences ;n a mobile radio system.
Further features of the invent;on are spec;f;ed in the subsequent claims.
The invention will now be described in greater detail w;th reference to the attached draw;ngs, ;n wh;ch Figure 1 illustrates how a mobile un;t ;s exposed to i 30 ;nterference from a ne;ghboring base station, Figure 2 illustrates how a base ;s exposed to ;nterference from a mobile unit in a neighboring area, ; Figures 3a and 3b are examples of cross-interference matrices, Figures 4a and 4b illustrate exclusion matrices belonging to 3S the cross-interference matr;ces ;n Figures 3a and 3b, the matrix in Figure 4b being a symmetrized downl;nk matr;x, Figure 5 illustrates an uplink matrix, . ~ . , , , . . .. : .. .. . .. .. - . . : . ~ : . . . .
VV~ 90il0342 2 ~ 7 ~ PCT/SE90/00130 Figure 6 illustrates an exclusion matrix belonging to the matrices in Figures 4b and 5, Figure 7 is an example of an exclusion matrix in table form, and Figures 8-10 are examples of plots of different interference situations.
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described in detail with reference to a mobile radio system.
The primary task of a mobile radio system is to handle mobile radio traffic and, for this reason, the first thing that has to be done in planning cel;s ;s to estimate how the traffic demand is geographically distributed. There may be cause for detailing how such a distribution is defined since the traffic demand at each geographical point in the working area of the rad;o system varies, for example with the times of day. It is clear that a type of distribution mus be used in a system which adapts itself to the variations in the traffic hour after hour by shutting down cells not required for the particular occasion and using a channel allocation which is tailored to this situation, and another type of distribution for the situation where all cells are always operating with one and the same channel allocation. In the latter case, which ;s based on the present state of the art in existing mobile rad;o systems, the cells must be dimensioned for maximum loads with a margin which corresponds to acceptable average blocking either calculated per cell or over the whole system as a total;ty.
Secondly, the cell planning must ensure that there is coverage ;n each case where the main proportion of the traffic demand occurs.
This in turn is determining for how the base station locations are selected and also which antennas will be used and how great the radiated power should be. Generally, only directional antennas are used. When the base station has been planned in this way, test measurements must be taken with respect to coverage and interference and arranged in a data base which includes the coverage and interference areas of all other base stations. Since at present aLmost the entire traffic demand is handled from the main routes in the path network, it is suffic;ent if the data base comprises , ............. . . . . . . . .
.: . . : .
... . . .
. '' . - . . . .
- , .: . . : .
:. . - -:
.. .- ... . - .
.
W O 90/10342 2 0 ~ 5 2 7 I PCT/SE90/00130 coverage and interferences with respect to these main routes. The base station must include sufficiently many channels per cell in order to be able to handle the traffic demand in the coverage area.
In the next step, a so-called exclusion matrix is c~-lculated for the entire mobile radio system in the geographic region in question, for example the Stockholm area.
The prerequisites are that there are a number of base stations each with its coverage area and a frequency band for the system with a limited number of channels. There is also a requirement for which C/I interference ratio is required for good reception and how much interference a receiver tolerates in adjoining channels. According to the invention, field strengths are measured along the important paths in the respective coverage areas~ From the measured values are calculated cross-interference matrices which specify with numeric values the interference ratios between transmitters. From the cross-interference matrices are calculated exclusion matrices which specify in symbolic form the ;nterference ratios between stations in different coverage areas, both mobile units and base stations. ~he channel allocation can be carried out w;th the help of the union of the exclusion matrices.
Using a specially calibrated receiver equipment, the receiver power from all base stations is measured on the relevant traffic routes in the geographic area which is occupied by the mobile radio system. The measured field strengths provide for these measurements mean values over sections of 20 m ~approx;mately 30 wavelengths) and each section is linked to a co-ordinate designation. The field strength values are represented ;n d~m in the measurement results of the rece;ved s;gnal power. The measurements are not as voluminous as they appear since field strengths from up to 12 base stations can be registered at one time in the same process. It is quite possible to make aLl necessary measurements for a cell ;nclud;ng coverage and interference range in one night. These type of measurements have already been carried out successfully ;n the Stockholm area.
The measurements provide knowledge on what potential power a rece;ver in a mobile unit should rece;ve from different cells wherever the mobile unit is located in the geographic area. It is also easy to calculate the power potentially received at an , ', -:
. .
. . : - :
.. ,~
, .. . . . . : ~ ~ . :
~ 90/10342 ~ 2 7 ~ PCr/SE90/00130 .
arbitrary base station and originating from mobile units in the coverage area. Accord;ngly, the interference situation both of the mobile units and of the base stations is known.
The exclusion matrix thus provides a systema~ic description in symbc~lic form of how different base stations or alternatively mobile units in different coverage areas can coexist with respect to the same channel and with respect to adjacent channels. The appearance of the matrix depends on which Limit values are set for interference and coverage. It ;s important to understand that although and exclusion matrix contains information on how channels can be arranged it is, nevertheless, not a frequency-based quantity but only describes the relations between field strengths in the space.
Since the interferences can be described on the one hand with respect to the base station receivers and on the other hand with respect to the receiver of the mobile units, there is an uplink matrix and a downlink matrix (naturally, only the downlink matrix is used in paging systems). If it were so that different channel allocations could be used in practice for uplinks and downlinks, these matrices, after symmetrization, could be used directly individually for constructing these allocations. However, it is intended to use the same allocation in both directions which implies that the allocating algorithms are applied to the union of these matrices.
The downlink situation is shown in Figure 1. Assume that all the base stations together with the corresponding service areas are numbered from 1 to N. In Figure 1, two stations i and j are shown with associated service areas. A mobile unit M in the i-th coverage area receives a wanted power Pi from its own base station and an unwanted interference power Pj from base station number j. There is a slight difference between the term "service area" and "coverage area". 9y coverage area are meant all measured paths which, with respect to a given base station, have a sufficiently high received power to permit satisfactory reception. In the service area, ; unmeasured points can be found which have good reception.
The minimum allowable CtI (carrier-to-interference) noise ratio for an acceptable co-channel quality is LP1 and the minimum allowable C/I for an acceptable qual;ty w;th noise in the first . ' .,:: . - . .. ..
.,'. ' ' -, ', : . , , -.. . .. ~
W O ~0/l0342 ~ 2 7 ~ Pcr/sE90/oo13o adjacent channel is LP2 and so forth. For the (k~ st adjacent channel, C/I must be greater than LPk, k < M. The disabling interference figure p is defined as the fraction of the coverage area for which it holds true that PitPj < LPk k = 1,2, ... M
M is the number of necessary co-channel and adjacent-channel limit values.
The element Pij in a general N-th-order cross-interference matrix is given by the relation Pij(LPk) = p The diagonal elements are set to zero, that is to say --Pii(LPk) = 0 for all i and k.
This cross-interference matrix P relates to the downlink situation and describes which degree of interference the mobile units are subject to w;th respect to the transmitting base stations.
Figure 2 ;llustrates the uplink situation. The Figure shows two base stations i and j w;th associated service areas. In this case the base station i is exposed to interference Qj from a mobile unit Mj in the coverage area of base station j. Base station i receives a wanted power ai from a mobile unit M; ;n its coverage area. The coverage areas are defined in the same way as earlier or are possibly adjusted for any ;mbalance in the power budgets for up- and downlink.
When the mobile unit Mj is assumed to pass through the entire coverage area of base j, an interference power is generated in base station ;. The ;nterference power at base stat;on ; wh;ch for y% of the coverage area of base station j exceeds the interference power generated by the mobile Mj is des;gnated by a jy. Su;table values of y can be 50 or 90. The m;nimum allowable C/I noise rat;o for an acceptable co-channel quality is des;gnated by LQ1 and the minimum C/I for an acceptable quality for the f;rst adjacent channel is designated by LQ2 and so forth. For the (k-1):st adjacent channel, ; C/I must be greater than LQk, k < M, in the same way as before.
The disabling interference f;gure q is defined as the fraction of the doverage area for base i for which it holds true that Qi/Qjy < LQk - :
.,, ' ' ~ ' ' ' - ' ~, 90/10342 ~ 2 7 ~ PCT/SE90/00130 A general N-th-order exclusion matrix is def;ned by the relation Qij(LQk) = q The diagonal elements are set to zero in the same way as before, that is to say Qii(LQk) = 0 for all i and k.
In this way, a cross-interference matrix is found for each k = 1,2 ... M. This cross-interference matrix Q relates to the uplink situation and describes the degree of interference 10 experienced by the receivers in the base stations with respect to --the transmitting mob;le units.
Alternatively, the uplink matrix can be calculated in the following way. When the mob;le unit Mj in Figure 2 oasses through the entire coverage area of base j, an interference power is generated in base i. The interference power varies in dependence on the instantaneous position of the interfering mobile unit and these d;fferent interference power results can be statistically characterized by means of a distribution function.
a) The distribut;on function is calculated with a starting point from the measured field strength values. The interference values are generated by performing a randomization (Monte-Carlo method) according to the said distribution which can be implemented, for example, by allowing all interference results to be represented in table form and performing a uniform selection over all numerical values of the table. All the values are stored each in the;r storage location, and the selection is effected uniformly over all the addresses of the storage locations.
Assume that a mobile unit Mi passes through the coverage area i and that the base thereby rece;ves the coverage field strength ai and a random interference field strength Qj when the mobile unit is located at a given point in the coverage area. The disabling interference figure q tq is the element Qij(LQk) in the cross-interference matrix for the uplink) is defined as the fraction of the coverage area of base i for which it holds true that Q;/Q; ~ LQk.
Due to ~he fact that the interference field strength Qj is random;zed, the rat;o Q;/Qj becomes a stochastic variable. The .. . .
- : , . . . . ~ .
WQ 90/10342 ~ i 2 7 ~ PCI`/SE90/00130 consequence is that Q is also a stochastic variable which assumes new values each time the calculation is carried out. In practice it is found that Q values calculated in this way are well assembled around their mean value and that a single result can be considered as being representative. If this should not prove sufficient there is always the possibility of estimating the mean value of q by simulating the effect of the interfering mobile unit several times in the way described above.
b) The distribution function is approximated by means of a logarithmically normal distribution~ It is well known in the literature that interference field strengths originating from mobile units situated at the same distance from the base have an almost logarithm;cally normal distribution. This also applies with good approximation to interference field strengths in a base from mobile units in an adjoining coverage area. The log-normal distribut;on is completely determined by mean vaLue and deviation which parameters can be easily calcuLated from given measured interference field strengths. Compared with case a) it is not the distribution function which is thus calculated but only the mean value and 2û deviation for the true distribution of the interference values. The true distribution is further approximated with a logarithmically normal distribution. The median for the true logarithmized interference field strengths can very well be used as mean value in the log-normal distribution. The simulated interference powers are generated with the a;d of a generator for normally distributed numerical values and with knowledge of the mean value and deviation as above.The elements Q;j(LQk) in the cross-interference matrix are calculated analogously to what is specified in a) above.
The power values Q in the base stations from transmitting mobile units are directly relateable to the power values P from transmitting base stations due to the fact that the transmiss;on losses between base and mobile unit are not dependent on the direction of transmission. Since P values are only obtained from measured wave propagation data this also applies to Q values.
To calculate the frequency compatibility each coverage area must be studied with respect to all the other coverage areas. This must be done for all the threshold values corresponding to the .
, -" ~ ' ` ' ' ~ : ' :
' ' ' , . ' ~ ' ~ ' ~Y~ 90/10342 ~ 2 7 ~ PCT/SEgo/00130 1 1 '.
co-channel interference and adjacent-channel ;nterference. This means that all the elements in all relevant cross-interference matrices must be calculated. In processing measurement data, it is generally unavoidable to calculate all the elements in the down- and S uplink matrices for the cross-interferences with respect to at least the co-channel case and the case of interference in the first adjacent channel, that is to say two cross-interference matrices must be calculated for downlink and two for uplink.
To make an allocation program which functions with a starting point from cross-interference matrices gives excellent results but it is easier to edit and make changes in the matrices, which is necessary if the matarices are to be used in practice, if they have a simpler form with information which is not quite so detailed. This is the reason why it is intended to go over to a simplified representation which is here called exclusion matrix. In the matrix, a distinction is made between at least three d;fferent degrees of interference which are usually called ., X or A in increasing degree of dignity. The symbol "." designates a disturbance which is negligible. The diagonal has elements which are usually designated by 0 and which specify which base station rows or columns in the matrix relate to, for example 0 in row number j means that all interferences relate to the coverage area of base station number j.
From the cross-interferences for the downlink with elements Pij(LPk), for example, a corresponding exclusion matrix can be formed in the following way:
Assume that the limit values for the same channel and the first adjacent channel area the only relevant ones, which implies that there are two cross-interference matrices PijtLP1) and PijtLP2). If the exclusion matrix is des;gnated by Uij and the limit value of the degree of disabl;ng interference is px in both cases, the matrix element uij is obtained in the following way ui; ="O"; i = j uij = "A"; Pij(LP2) > px uij = "X"; Pij(LP1) > px uij = "."; Pij(LP1) < px The matrix elements vij in the uplink matrix are formed in corresponding manner by using the cross-interference matrices ' , , '.
.
- : , :
- .:. - , .. : ~
'~ ~ - - ' : ' ' ' .
W O 90/10342 ~ 7 ~ PCT/SE90/00130 QijtLQ2) and Qij(LQ1) and corresponding limit value for the degree of disabling interference py.
In Figure 3a, an example of a cross-interference matrix Pij(LP2) is shown and in Figure 3b a cross-interference matrix Pij(LP1) is shown~ It holds true that Pij(LP2) < Pij(LP1); for the rest, there is no connection between the matrices, and the matrices are not symmetrical either.
By using the above method, an exclusion matrix can be calculated by means of the cross-interference matrices in Figures 3a and 3b for Px = 0.05. The exclusion matrix is shown in Figure 4a.
The symbols ".", "X" and "A" correspond to interferences of increasing degree of dignity. An interference corresponding to "."
is acceptable as co-channel interference. The symbol "O" indicates which coverage area the interferences in the same column relate to.
The matrix according to Figure 4a can be interpreted as follows. A
mobiLe unit w;th coverage from base station 1 cannot share a channel for reception with a mobile unit in coverage areas 2 and 4. However, it can share a channel with a mobile unit in coverage area 3. A
channel adjacent to a channel used by a mobile unit in coverage area 20 4 cannot be used by it. On the other hand, a mobile unit with --coverage from base station 2 can share a channel for reception with a mobile unit in coverage area 1. A mobile unit in coverage area 2 ;s thus not exposed to interferences from base station 1, but a mobile unit in coverage area 1, is exposed to interferences from base station 2. Naturally, in practice this implies that the base stations 1 and 2 cannot use the same transmitting frequency. The consequence ;s that only symmetrical exclusion matrices have any pract;cal value.
The exclusion matrix is therefore symmetrized by letting matrix elements which represent the stronger interference degree apply. If the matrix in Figure 4a is 5ymmetrized, the matrix in Figure 4b is obtained which represents the downlink matrix in this case.
An example of an uplink matrix is given in Figure 5. According to this matrix, the base station 1, in receiving mode, cannot share a channel with base stations Z, 3 and 4 and cannot have an adjacent channel to base station 4. Base station 2 is exposed to negligible interference from moh;le units in the coverage areas of base ,: :
-~ ' ' ' - : -- wo 90/10342 ~ 7 ~ PCI /SE90/00130 stations 3 and 4 and can therefore share a channel with these base stations, and so forth.
As has been previously mentioned, one would like to have the same channel allocations in the uplink and downlink directins. To produce a matrix which can be used for forming the same alloca~ion in both directions, the union of matrices U and V is defined. The union of two matrices is defined as the matrix with the union of corresponding elrments in each matrix. The symbol for the union of two matrix elements is the symbol for the element which represents 1û the stronger interference.
In Figure 6, the union of the matrices in Figures 4b and 5 is shown. For the allocation of the channels, the exclus;on matrix thus combined ;s used by combining its rows. If a certain control is desired so that small interference contributions which are individually allowed do not add up too much during the allocation, for example, a further two levels "Y" and "Z" can be introduced in the following manner. For the downlink matrix, the matrix element is set as uij = "o~; ; = j 2û uij = "A"; Pij(LPZ) > px uij = "X"; Pij(LP1) > px uij = "Y"; px/2 < P;j(LP1) < px uij = "Z"; px/4 ~ P;j(LP1) < px/2 uij = "."; Pij(LP1) < px(4 where px = the limit value of the degree of disabling interference in the same way as before. The exclus;on natrix for the uplink situation can be formed in correspond;ng manner in certain cases. This is possible especially when the uplink interference is calculated with the a;d of the statistical methods descr;bed earlier.
Figure 7 shows an example of an exclus;on matr;x calculated for base stations ;n Stockholm. The matrix ;s represented in table form so that ;t can be read more eas;ly. The X exclusions are specified in groups of f;ve rows and the A exclus;ons in groups of three rows for each base station record. From this list, it can be read, for example, that Hagalund, as record number 7, cannot have the same channel as Hallonbergen at record number 8 due to the fact that 8 . ,, , .
- . : . .
-: ~ ~- .
-- . -- -- .
WO 90/103'~ i f~ 7 ~ PCr/SE90/00130 occurs as X exclusion at record number 7 and vice versa.
A further aid in the same resource allocation is a plotting program which produces plots of the interference situation. This is because the elements in an exclusion matrix belong to one of the following three classes:
- 1. Obvious non-exclusions, for example between cells at a very long distance from one another. It is sufficient to calculate that the coverage areas do not overlap one another, that is to say a trivial calculation.
1û 2. Obvious exclusions between, for example, cells grouped together, that is to say cells which share the same mast or antenna.
Collective groupings are found easily by comparing co-ordinates of the stations.
3. Uncertain pairs of cells where it is difficult to determine whether there is an exclusion or not. The set of uncertain pairs is a much smaller set than the set of all cell pairs.
Strictly speaking, in constructing an exclusion matrix, only the elements in the cross-interference matrices need be calculated ~which relate to uncertain cell pairs. This is suitably done by means -20 of the algorithms specified earlier in combination with the plotting programs which present plots of down- and uplinks for cell pairs in question. For the uplink, the Monte-Carlo methods specified in a) and b) are to be preferred. The plotting programs calculate the degree of interference (the value of corresponding elements in the cross-interference matrix) and gives a visual illustration of the interference situation which provides an extremely accurate plan of the cell and its ;nteraction with other cells. The planning can now be carried out not only with respect to the interference figure but also with respect to the total interference pattern and with 3û system-related aspects in mind such as, for example, hand-over boundaries. It is poss1ble to vary base station powers and power classes for mobile units and also individually to regulate the coverage for each cell. This can be done simultaneously both for down- and uplink. In addition, one need no longer be tied to a fixed limit value for the interference figure, but instead one can individually plan the cells with respect to the unique interference pattern.
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FIELD OF THE INVENTION
The present invention relates to a method for planning radio --rells, particularly planning cells with control over the interaction between the cells in the system and the capability of channel allocations which vary in accordance with the traffic demand. The method utilizes field strength measurements and an allocating algorithm, which permit a simple adaptation of the cell system~ that is to say increasing or decreasing the number of cells with altered traffic demand. In particular, the invention relates to the planning of mobile radio cells. The changes in the traffic demand can relate to diurnal variations in the traffic and more long-term variations due to changes in the route network and so forth.
The present invention also relates to a method for constructing an exclusion matrix for resource allocation in a radio system. The radio system can be unidirectional with communication in only one direction, for example a paging system, or bidirectional, for example a mobile radio system. In the application, a mobile radio system is preferably considered, but it is understood that the Z5 invention is aLso applicable to a unidirectional system. In a mob;le radio system, it is of importance that the available frequence resources are used in such a manner that the system caPaCity is optimized under the condition that the customers obtain an acceptable quality. In a microcell system in a densely populated area, ;t is des;rable that the channel allocation can be ta;lored to the actual traffic d;stribution. Such planning ;s a very demanding task and there are great sains to be made if the operator of the system has full control over the inherent interferences in the system. An improved quality and traffic handling in a given frequency range is, moreover, equivalent to an increased frequency economy.
The follow;ng prerequisites are given: a distribution of , .
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-, WQ 90/10342 2 ~ ~ ~ 2 ~ ~PCT/SE90/00130 traffic demand over, for example, Stockholm, system parameters which define which C/I ~carrier to interference) interference ratio is required for good reception and how much interference a receiver tolerates in adjoining channels, and a frequency band for the system with a limited number of channels. It is the object to distr;bute the channels to the different base stations in the given frequency range so that the quality of connection experienced by the customers satisfies the given minimum requirements.
The present invention further relates to a method for determining uplink interferences in a mobi(e radio system, that is to say determining the degree of interference in a cell with respect to interfering mobile units in another cell.
STATE OF THE ART
Earlier mobile radio cell planning methods were static methods, that is to say all cells are always operating with one and the same channel allocation. Since direct f;eld strength measurements have not been utilized previously, there has been no check of the factual interference ratios and it has been diff;cult to make new channel allocations. It is an uneconomical utilization of the resources for all cells to be operating at all times.
According to the first aspect of the ;nvention, there is complete control over the interference ratios, that ;s to say the interaction in the system, at all times. The invention thus offers a method which provides for simple adaptation to the prevailing traffic demand.
In the art, the problem of resource allocat;on has been solved ; essentially as follows: a systematic descr;pt;on is g;ven of all the restr;ct;ons which apply to channel d;str;but;on ;n the form of a so-called exclus;on matrix. An exclusion matrix provides a description in symbol;c form of how different base stat;ons, or alternat;vely mobile un;ts in d;fferent coverage areas, can coexist with respect to the same channel and with respect to the adjacent channel. Then allocation algorithms are used for finding exactly which channels the different base stations should have for the 35 minimum requirements for the connection quality to be satisfied. The -method is used little since it is difficult to character;ze a large city with respect to wave propagation ;n such a manner that a useful ~ , , . . . :. .
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YyO 90/10342 ~ ~ ~ 5 h 7 ~ P ~ /SE90/00130 field strength and interference field strengths can be predicted within a few d~ at relevant points, for example along the main traffic routes~ There are examples of attempts made with large prediction programs based on terrain models. In reality, however, there is no possibility of putting in information about how, for example, all antenna patterns look with their in reality extremely irregular patterns. Such attempts thus have a tendency to create completely unrealistic calculat;on volumes.
According to the second aspect of the invention, basically 1û simple and completely realistic methods are used for providing the wave propagation information which is suitable for calculating an exclusion matrix~ for example for Stocholm. The exclusion matrix in turn makes it possible to run an allocation program, and channel allocations are obtained for a situation with very well known and desired interference ratios which ensure a good communication quality.
When determin;ng degrees of interference in mobile radio systems, only the downlink interferences have previously been considered, that is to say disturbances from base stations in other cells. It has been assumed that this is sufficient, especially since there has not been any method for characterizing interference from the moving mobile units in other cells. However, it has been shown that there can be a significant difference between the downlink and uplink interferences. Normally, the degree of interference is greater ;n the uplink situation than in the downlink situation. This implies that a resource allocation can be constructed which has an acceptable degree of downlink interference but too h;gh a degree of uplink ;nterference, wh;ch naturally ;mplies that the system is unacceptable overall.
According to the third aspect of the present invention, it is now possible to determine in an effective way the degree of interference for the uplink case so that th;s problem can be remedied.
SUMMARY OF THE INVENTION
According to the invent;on, a method for planning radio cells is provided, according to which:
the traffic demand is estimated geograph;cally;
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- . . . - . . -W O 90/l0342 ~ 2 7 ~ PCT/SE90/00130 an acceptabte coverage of the traffic demand i5 produced with the aid of a number of cells with suitable transmitter powers and antenna arrangements;
coverage and interference measurements are carried out for the cells, which measurement results are stored in a measurement data base;
each cell is allocated a number of channels which corresponds to the estimated traffic demand having regard to a margin for acceptable blocking;
1û an exclusion matrix is calculated on the bas;s of the ~ measurement results, which matr;x represents the interaction between the cells in the system;
an allocating algorithm is iterated, which algorithm, by - utilizing a random technique, provides different sets of channet aLlocations for the cells;
;f ;t is not poss;ble to allocate channels with respect to the maximum number of channels, a new attempt is made, and an acceptable radio cell design is obtained if the channel number was sufficiently high.
The present invention also provides a method for constructing the above exclusion matrix for optimum channel allocation.
The present ;nvention further prov;des a method for determining upl;nk interferences ;n a mobile radio system.
Further features of the invent;on are spec;f;ed in the subsequent claims.
The invention will now be described in greater detail w;th reference to the attached draw;ngs, ;n wh;ch Figure 1 illustrates how a mobile un;t ;s exposed to i 30 ;nterference from a ne;ghboring base station, Figure 2 illustrates how a base ;s exposed to ;nterference from a mobile unit in a neighboring area, ; Figures 3a and 3b are examples of cross-interference matrices, Figures 4a and 4b illustrate exclusion matrices belonging to 3S the cross-interference matr;ces ;n Figures 3a and 3b, the matrix in Figure 4b being a symmetrized downl;nk matr;x, Figure 5 illustrates an uplink matrix, . ~ . , , , . . .. : .. .. . .. .. - . . : . ~ : . . . .
VV~ 90il0342 2 ~ 7 ~ PCT/SE90/00130 Figure 6 illustrates an exclusion matrix belonging to the matrices in Figures 4b and 5, Figure 7 is an example of an exclusion matrix in table form, and Figures 8-10 are examples of plots of different interference situations.
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described in detail with reference to a mobile radio system.
The primary task of a mobile radio system is to handle mobile radio traffic and, for this reason, the first thing that has to be done in planning cel;s ;s to estimate how the traffic demand is geographically distributed. There may be cause for detailing how such a distribution is defined since the traffic demand at each geographical point in the working area of the rad;o system varies, for example with the times of day. It is clear that a type of distribution mus be used in a system which adapts itself to the variations in the traffic hour after hour by shutting down cells not required for the particular occasion and using a channel allocation which is tailored to this situation, and another type of distribution for the situation where all cells are always operating with one and the same channel allocation. In the latter case, which ;s based on the present state of the art in existing mobile rad;o systems, the cells must be dimensioned for maximum loads with a margin which corresponds to acceptable average blocking either calculated per cell or over the whole system as a total;ty.
Secondly, the cell planning must ensure that there is coverage ;n each case where the main proportion of the traffic demand occurs.
This in turn is determining for how the base station locations are selected and also which antennas will be used and how great the radiated power should be. Generally, only directional antennas are used. When the base station has been planned in this way, test measurements must be taken with respect to coverage and interference and arranged in a data base which includes the coverage and interference areas of all other base stations. Since at present aLmost the entire traffic demand is handled from the main routes in the path network, it is suffic;ent if the data base comprises , ............. . . . . . . . .
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W O 90/10342 2 0 ~ 5 2 7 I PCT/SE90/00130 coverage and interferences with respect to these main routes. The base station must include sufficiently many channels per cell in order to be able to handle the traffic demand in the coverage area.
In the next step, a so-called exclusion matrix is c~-lculated for the entire mobile radio system in the geographic region in question, for example the Stockholm area.
The prerequisites are that there are a number of base stations each with its coverage area and a frequency band for the system with a limited number of channels. There is also a requirement for which C/I interference ratio is required for good reception and how much interference a receiver tolerates in adjoining channels. According to the invention, field strengths are measured along the important paths in the respective coverage areas~ From the measured values are calculated cross-interference matrices which specify with numeric values the interference ratios between transmitters. From the cross-interference matrices are calculated exclusion matrices which specify in symbolic form the ;nterference ratios between stations in different coverage areas, both mobile units and base stations. ~he channel allocation can be carried out w;th the help of the union of the exclusion matrices.
Using a specially calibrated receiver equipment, the receiver power from all base stations is measured on the relevant traffic routes in the geographic area which is occupied by the mobile radio system. The measured field strengths provide for these measurements mean values over sections of 20 m ~approx;mately 30 wavelengths) and each section is linked to a co-ordinate designation. The field strength values are represented ;n d~m in the measurement results of the rece;ved s;gnal power. The measurements are not as voluminous as they appear since field strengths from up to 12 base stations can be registered at one time in the same process. It is quite possible to make aLl necessary measurements for a cell ;nclud;ng coverage and interference range in one night. These type of measurements have already been carried out successfully ;n the Stockholm area.
The measurements provide knowledge on what potential power a rece;ver in a mobile unit should rece;ve from different cells wherever the mobile unit is located in the geographic area. It is also easy to calculate the power potentially received at an , ', -:
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arbitrary base station and originating from mobile units in the coverage area. Accord;ngly, the interference situation both of the mobile units and of the base stations is known.
The exclusion matrix thus provides a systema~ic description in symbc~lic form of how different base stations or alternatively mobile units in different coverage areas can coexist with respect to the same channel and with respect to adjacent channels. The appearance of the matrix depends on which Limit values are set for interference and coverage. It ;s important to understand that although and exclusion matrix contains information on how channels can be arranged it is, nevertheless, not a frequency-based quantity but only describes the relations between field strengths in the space.
Since the interferences can be described on the one hand with respect to the base station receivers and on the other hand with respect to the receiver of the mobile units, there is an uplink matrix and a downlink matrix (naturally, only the downlink matrix is used in paging systems). If it were so that different channel allocations could be used in practice for uplinks and downlinks, these matrices, after symmetrization, could be used directly individually for constructing these allocations. However, it is intended to use the same allocation in both directions which implies that the allocating algorithms are applied to the union of these matrices.
The downlink situation is shown in Figure 1. Assume that all the base stations together with the corresponding service areas are numbered from 1 to N. In Figure 1, two stations i and j are shown with associated service areas. A mobile unit M in the i-th coverage area receives a wanted power Pi from its own base station and an unwanted interference power Pj from base station number j. There is a slight difference between the term "service area" and "coverage area". 9y coverage area are meant all measured paths which, with respect to a given base station, have a sufficiently high received power to permit satisfactory reception. In the service area, ; unmeasured points can be found which have good reception.
The minimum allowable CtI (carrier-to-interference) noise ratio for an acceptable co-channel quality is LP1 and the minimum allowable C/I for an acceptable qual;ty w;th noise in the first . ' .,:: . - . .. ..
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W O ~0/l0342 ~ 2 7 ~ Pcr/sE90/oo13o adjacent channel is LP2 and so forth. For the (k~ st adjacent channel, C/I must be greater than LPk, k < M. The disabling interference figure p is defined as the fraction of the coverage area for which it holds true that PitPj < LPk k = 1,2, ... M
M is the number of necessary co-channel and adjacent-channel limit values.
The element Pij in a general N-th-order cross-interference matrix is given by the relation Pij(LPk) = p The diagonal elements are set to zero, that is to say --Pii(LPk) = 0 for all i and k.
This cross-interference matrix P relates to the downlink situation and describes which degree of interference the mobile units are subject to w;th respect to the transmitting base stations.
Figure 2 ;llustrates the uplink situation. The Figure shows two base stations i and j w;th associated service areas. In this case the base station i is exposed to interference Qj from a mobile unit Mj in the coverage area of base station j. Base station i receives a wanted power ai from a mobile unit M; ;n its coverage area. The coverage areas are defined in the same way as earlier or are possibly adjusted for any ;mbalance in the power budgets for up- and downlink.
When the mobile unit Mj is assumed to pass through the entire coverage area of base j, an interference power is generated in base station ;. The ;nterference power at base stat;on ; wh;ch for y% of the coverage area of base station j exceeds the interference power generated by the mobile Mj is des;gnated by a jy. Su;table values of y can be 50 or 90. The m;nimum allowable C/I noise rat;o for an acceptable co-channel quality is des;gnated by LQ1 and the minimum C/I for an acceptable quality for the f;rst adjacent channel is designated by LQ2 and so forth. For the (k-1):st adjacent channel, ; C/I must be greater than LQk, k < M, in the same way as before.
The disabling interference f;gure q is defined as the fraction of the doverage area for base i for which it holds true that Qi/Qjy < LQk - :
.,, ' ' ~ ' ' ' - ' ~, 90/10342 ~ 2 7 ~ PCT/SE90/00130 A general N-th-order exclusion matrix is def;ned by the relation Qij(LQk) = q The diagonal elements are set to zero in the same way as before, that is to say Qii(LQk) = 0 for all i and k.
In this way, a cross-interference matrix is found for each k = 1,2 ... M. This cross-interference matrix Q relates to the uplink situation and describes the degree of interference 10 experienced by the receivers in the base stations with respect to --the transmitting mob;le units.
Alternatively, the uplink matrix can be calculated in the following way. When the mob;le unit Mj in Figure 2 oasses through the entire coverage area of base j, an interference power is generated in base i. The interference power varies in dependence on the instantaneous position of the interfering mobile unit and these d;fferent interference power results can be statistically characterized by means of a distribution function.
a) The distribut;on function is calculated with a starting point from the measured field strength values. The interference values are generated by performing a randomization (Monte-Carlo method) according to the said distribution which can be implemented, for example, by allowing all interference results to be represented in table form and performing a uniform selection over all numerical values of the table. All the values are stored each in the;r storage location, and the selection is effected uniformly over all the addresses of the storage locations.
Assume that a mobile unit Mi passes through the coverage area i and that the base thereby rece;ves the coverage field strength ai and a random interference field strength Qj when the mobile unit is located at a given point in the coverage area. The disabling interference figure q tq is the element Qij(LQk) in the cross-interference matrix for the uplink) is defined as the fraction of the coverage area of base i for which it holds true that Q;/Q; ~ LQk.
Due to ~he fact that the interference field strength Qj is random;zed, the rat;o Q;/Qj becomes a stochastic variable. The .. . .
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WQ 90/10342 ~ i 2 7 ~ PCI`/SE90/00130 consequence is that Q is also a stochastic variable which assumes new values each time the calculation is carried out. In practice it is found that Q values calculated in this way are well assembled around their mean value and that a single result can be considered as being representative. If this should not prove sufficient there is always the possibility of estimating the mean value of q by simulating the effect of the interfering mobile unit several times in the way described above.
b) The distribution function is approximated by means of a logarithmically normal distribution~ It is well known in the literature that interference field strengths originating from mobile units situated at the same distance from the base have an almost logarithm;cally normal distribution. This also applies with good approximation to interference field strengths in a base from mobile units in an adjoining coverage area. The log-normal distribut;on is completely determined by mean vaLue and deviation which parameters can be easily calcuLated from given measured interference field strengths. Compared with case a) it is not the distribution function which is thus calculated but only the mean value and 2û deviation for the true distribution of the interference values. The true distribution is further approximated with a logarithmically normal distribution. The median for the true logarithmized interference field strengths can very well be used as mean value in the log-normal distribution. The simulated interference powers are generated with the a;d of a generator for normally distributed numerical values and with knowledge of the mean value and deviation as above.The elements Q;j(LQk) in the cross-interference matrix are calculated analogously to what is specified in a) above.
The power values Q in the base stations from transmitting mobile units are directly relateable to the power values P from transmitting base stations due to the fact that the transmiss;on losses between base and mobile unit are not dependent on the direction of transmission. Since P values are only obtained from measured wave propagation data this also applies to Q values.
To calculate the frequency compatibility each coverage area must be studied with respect to all the other coverage areas. This must be done for all the threshold values corresponding to the .
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co-channel interference and adjacent-channel ;nterference. This means that all the elements in all relevant cross-interference matrices must be calculated. In processing measurement data, it is generally unavoidable to calculate all the elements in the down- and S uplink matrices for the cross-interferences with respect to at least the co-channel case and the case of interference in the first adjacent channel, that is to say two cross-interference matrices must be calculated for downlink and two for uplink.
To make an allocation program which functions with a starting point from cross-interference matrices gives excellent results but it is easier to edit and make changes in the matrices, which is necessary if the matarices are to be used in practice, if they have a simpler form with information which is not quite so detailed. This is the reason why it is intended to go over to a simplified representation which is here called exclusion matrix. In the matrix, a distinction is made between at least three d;fferent degrees of interference which are usually called ., X or A in increasing degree of dignity. The symbol "." designates a disturbance which is negligible. The diagonal has elements which are usually designated by 0 and which specify which base station rows or columns in the matrix relate to, for example 0 in row number j means that all interferences relate to the coverage area of base station number j.
From the cross-interferences for the downlink with elements Pij(LPk), for example, a corresponding exclusion matrix can be formed in the following way:
Assume that the limit values for the same channel and the first adjacent channel area the only relevant ones, which implies that there are two cross-interference matrices PijtLP1) and PijtLP2). If the exclusion matrix is des;gnated by Uij and the limit value of the degree of disabl;ng interference is px in both cases, the matrix element uij is obtained in the following way ui; ="O"; i = j uij = "A"; Pij(LP2) > px uij = "X"; Pij(LP1) > px uij = "."; Pij(LP1) < px The matrix elements vij in the uplink matrix are formed in corresponding manner by using the cross-interference matrices ' , , '.
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W O 90/10342 ~ 7 ~ PCT/SE90/00130 QijtLQ2) and Qij(LQ1) and corresponding limit value for the degree of disabling interference py.
In Figure 3a, an example of a cross-interference matrix Pij(LP2) is shown and in Figure 3b a cross-interference matrix Pij(LP1) is shown~ It holds true that Pij(LP2) < Pij(LP1); for the rest, there is no connection between the matrices, and the matrices are not symmetrical either.
By using the above method, an exclusion matrix can be calculated by means of the cross-interference matrices in Figures 3a and 3b for Px = 0.05. The exclusion matrix is shown in Figure 4a.
The symbols ".", "X" and "A" correspond to interferences of increasing degree of dignity. An interference corresponding to "."
is acceptable as co-channel interference. The symbol "O" indicates which coverage area the interferences in the same column relate to.
The matrix according to Figure 4a can be interpreted as follows. A
mobiLe unit w;th coverage from base station 1 cannot share a channel for reception with a mobile unit in coverage areas 2 and 4. However, it can share a channel with a mobile unit in coverage area 3. A
channel adjacent to a channel used by a mobile unit in coverage area 20 4 cannot be used by it. On the other hand, a mobile unit with --coverage from base station 2 can share a channel for reception with a mobile unit in coverage area 1. A mobile unit in coverage area 2 ;s thus not exposed to interferences from base station 1, but a mobile unit in coverage area 1, is exposed to interferences from base station 2. Naturally, in practice this implies that the base stations 1 and 2 cannot use the same transmitting frequency. The consequence ;s that only symmetrical exclusion matrices have any pract;cal value.
The exclusion matrix is therefore symmetrized by letting matrix elements which represent the stronger interference degree apply. If the matrix in Figure 4a is 5ymmetrized, the matrix in Figure 4b is obtained which represents the downlink matrix in this case.
An example of an uplink matrix is given in Figure 5. According to this matrix, the base station 1, in receiving mode, cannot share a channel with base stations Z, 3 and 4 and cannot have an adjacent channel to base station 4. Base station 2 is exposed to negligible interference from moh;le units in the coverage areas of base ,: :
-~ ' ' ' - : -- wo 90/10342 ~ 7 ~ PCI /SE90/00130 stations 3 and 4 and can therefore share a channel with these base stations, and so forth.
As has been previously mentioned, one would like to have the same channel allocations in the uplink and downlink directins. To produce a matrix which can be used for forming the same alloca~ion in both directions, the union of matrices U and V is defined. The union of two matrices is defined as the matrix with the union of corresponding elrments in each matrix. The symbol for the union of two matrix elements is the symbol for the element which represents 1û the stronger interference.
In Figure 6, the union of the matrices in Figures 4b and 5 is shown. For the allocation of the channels, the exclus;on matrix thus combined ;s used by combining its rows. If a certain control is desired so that small interference contributions which are individually allowed do not add up too much during the allocation, for example, a further two levels "Y" and "Z" can be introduced in the following manner. For the downlink matrix, the matrix element is set as uij = "o~; ; = j 2û uij = "A"; Pij(LPZ) > px uij = "X"; Pij(LP1) > px uij = "Y"; px/2 < P;j(LP1) < px uij = "Z"; px/4 ~ P;j(LP1) < px/2 uij = "."; Pij(LP1) < px(4 where px = the limit value of the degree of disabling interference in the same way as before. The exclus;on natrix for the uplink situation can be formed in correspond;ng manner in certain cases. This is possible especially when the uplink interference is calculated with the a;d of the statistical methods descr;bed earlier.
Figure 7 shows an example of an exclus;on matr;x calculated for base stations ;n Stockholm. The matrix ;s represented in table form so that ;t can be read more eas;ly. The X exclusions are specified in groups of f;ve rows and the A exclus;ons in groups of three rows for each base station record. From this list, it can be read, for example, that Hagalund, as record number 7, cannot have the same channel as Hallonbergen at record number 8 due to the fact that 8 . ,, , .
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WO 90/103'~ i f~ 7 ~ PCr/SE90/00130 occurs as X exclusion at record number 7 and vice versa.
A further aid in the same resource allocation is a plotting program which produces plots of the interference situation. This is because the elements in an exclusion matrix belong to one of the following three classes:
- 1. Obvious non-exclusions, for example between cells at a very long distance from one another. It is sufficient to calculate that the coverage areas do not overlap one another, that is to say a trivial calculation.
1û 2. Obvious exclusions between, for example, cells grouped together, that is to say cells which share the same mast or antenna.
Collective groupings are found easily by comparing co-ordinates of the stations.
3. Uncertain pairs of cells where it is difficult to determine whether there is an exclusion or not. The set of uncertain pairs is a much smaller set than the set of all cell pairs.
Strictly speaking, in constructing an exclusion matrix, only the elements in the cross-interference matrices need be calculated ~which relate to uncertain cell pairs. This is suitably done by means -20 of the algorithms specified earlier in combination with the plotting programs which present plots of down- and uplinks for cell pairs in question. For the uplink, the Monte-Carlo methods specified in a) and b) are to be preferred. The plotting programs calculate the degree of interference (the value of corresponding elements in the cross-interference matrix) and gives a visual illustration of the interference situation which provides an extremely accurate plan of the cell and its ;nteraction with other cells. The planning can now be carried out not only with respect to the interference figure but also with respect to the total interference pattern and with 3û system-related aspects in mind such as, for example, hand-over boundaries. It is poss1ble to vary base station powers and power classes for mobile units and also individually to regulate the coverage for each cell. This can be done simultaneously both for down- and uplink. In addition, one need no longer be tied to a fixed limit value for the interference figure, but instead one can individually plan the cells with respect to the unique interference pattern.
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For example, interferences do not give rise to any problems with normal traffic loading in cases where these interferences can be considered as belonging to the coverage area of ano~her cell. The method is work-intensive but provides a result of extremely high quality.
The exclusion matrix allows a number of channel allocations to be constructed for the current system with the aid of so-called allocating algorithms, and this takes into account all e~isting relevant secondary conditions in the system with respect to limit values for co- and adjacent-channel interferences, adjoining boundar;es with fixed allocations and so forth. A suitable method for channel allocation is specified in our international patent application "Method for channel allocation in a radio system" with the same filing date as the present application.
From the set of channel allocations, it can be assessed to what extent the traffic occurring in the newly planned cell can be handled within the given number of allowed channels. If this cannot be done, it can either be attempted to adjust the transmitter powers or antenna arrangement in an environment of the newly planned coverage area or the coverage area can possibly be divided up into a greater number of smaller cells. This is followed by a new calculat;on of the exclusion matrix and construction of further channel allocations. All situations which provide a number of channels within the maximum allowed number is considered as capable of implementation.
What has been descr;bed here ;s an interactive ;terat;ve procedure between man and computer. In pr;nc;ple, cells can always be added w;th;n the same frequency range prov;ded that ind;vidual coverages are suff;c;ently small. The cost of th;s type of planning lies mainly ;n the number of new cells wh;ch must be added in order to absorb the newly added traffic demand. Each cell has a certain traffic handling capability and it is obvious that the traffic handled per unit area increases with increased number of cells.
The procedure ;s iterative and relates to a method w;th successive expansion of an existing mobile radio cell system with at least one base station in the initial stage. Naturally, for a number of already existing base stations, any of these can be set up for . . . - . . , - . , . - .
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W O 90/10342 ~ 2 7 ~ PC~r/SE90/00130 replanning according to the itera~ive procedure below. The overall strategy for the cell planning in question cannot be described with the aid of a "cookbook" but must be left to the operator's judgement and knowledge of the characteristics of the mobile radio system. The S procedure includes the following main points:
1. Geographically estimating the traffic demand.
2. Achieving in a suitable manner and with the least possible ~ -resources in question with regard to transmitter power and antenna arrangement, one or several cells with coverage which captures an acceptable proportion of the traffic demand.
For example, interferences do not give rise to any problems with normal traffic loading in cases where these interferences can be considered as belonging to the coverage area of ano~her cell. The method is work-intensive but provides a result of extremely high quality.
The exclusion matrix allows a number of channel allocations to be constructed for the current system with the aid of so-called allocating algorithms, and this takes into account all e~isting relevant secondary conditions in the system with respect to limit values for co- and adjacent-channel interferences, adjoining boundar;es with fixed allocations and so forth. A suitable method for channel allocation is specified in our international patent application "Method for channel allocation in a radio system" with the same filing date as the present application.
From the set of channel allocations, it can be assessed to what extent the traffic occurring in the newly planned cell can be handled within the given number of allowed channels. If this cannot be done, it can either be attempted to adjust the transmitter powers or antenna arrangement in an environment of the newly planned coverage area or the coverage area can possibly be divided up into a greater number of smaller cells. This is followed by a new calculat;on of the exclusion matrix and construction of further channel allocations. All situations which provide a number of channels within the maximum allowed number is considered as capable of implementation.
What has been descr;bed here ;s an interactive ;terat;ve procedure between man and computer. In pr;nc;ple, cells can always be added w;th;n the same frequency range prov;ded that ind;vidual coverages are suff;c;ently small. The cost of th;s type of planning lies mainly ;n the number of new cells wh;ch must be added in order to absorb the newly added traffic demand. Each cell has a certain traffic handling capability and it is obvious that the traffic handled per unit area increases with increased number of cells.
The procedure ;s iterative and relates to a method w;th successive expansion of an existing mobile radio cell system with at least one base station in the initial stage. Naturally, for a number of already existing base stations, any of these can be set up for . . . - . . , - . , . - .
.. . . ~ :
W O 90/10342 ~ 2 7 ~ PC~r/SE90/00130 replanning according to the itera~ive procedure below. The overall strategy for the cell planning in question cannot be described with the aid of a "cookbook" but must be left to the operator's judgement and knowledge of the characteristics of the mobile radio system. The S procedure includes the following main points:
1. Geographically estimating the traffic demand.
2. Achieving in a suitable manner and with the least possible ~ -resources in question with regard to transmitter power and antenna arrangement, one or several cells with coverage which captures an acceptable proportion of the traffic demand.
3. Carrying out coverage and interference measurements of the cell or cells.
Updating the measurement data base with this information.
Carrying out plotting of coverages of cells concerned and interferences in adjoining cells. The plots are done for ;nterferences both from base to mob;le ~downl;nk) and for interferences from mob;le to base (uplink). Interferences are calculated in plotting programs advantageously according to the methods for constructing an exclus;on matr;x and determining Z0 upl;nk interferences as set forth above. The interaction between cells, that is to say whether exclusion or not will exist w;th respect to channels, can be assessed w;th the aid of plots having regard to system aspects such as where hand-over boundaries should suitably be and so forth. With the aid of plotting programs, fine adjustments can thus be carried out with respect to power classes for mobile units and base stat;on powers, the whole t;me w;th full control of coverage and degree of ;nterference both ;n down- and upl;nk.
Updating the measurement data base with this information.
Carrying out plotting of coverages of cells concerned and interferences in adjoining cells. The plots are done for ;nterferences both from base to mob;le ~downl;nk) and for interferences from mob;le to base (uplink). Interferences are calculated in plotting programs advantageously according to the methods for constructing an exclus;on matr;x and determining Z0 upl;nk interferences as set forth above. The interaction between cells, that is to say whether exclusion or not will exist w;th respect to channels, can be assessed w;th the aid of plots having regard to system aspects such as where hand-over boundaries should suitably be and so forth. With the aid of plotting programs, fine adjustments can thus be carried out with respect to power classes for mobile units and base stat;on powers, the whole t;me w;th full control of coverage and degree of ;nterference both ;n down- and upl;nk.
4. Plann;ng the number of channels per cell which corresponds to the estimated traffic demand including a margin of acceptable blocking calculated, for example, for maximum traffic.
5. Calculating the exclus;on matr;x for a suitably large geograph;cal area dependent on the interaction with the ; environment which the re- or new plann;ng produces.
6. Using allocat;ng algorithms of the Monte-Carlo type ~random ` techn;que). Consideration is g;ven to boundar;es with allocationsalready made. A set of channel allocations is obtained which . .
:' `; ' :
- ' ' ', ' ' '. . ~ :
. . :
Y~O 90/10342 ~ 1'CT/SE90/00130 provides information on the possibility of implementing the new arrangement within the specified bandwidth.
:' `; ' :
- ' ' ', ' ' '. . ~ :
. . :
Y~O 90/10342 ~ 1'CT/SE90/00130 provides information on the possibility of implementing the new arrangement within the specified bandwidth.
7. If implementation is not possible, at least one of the added cells or a second existing cell must be divided up into smaller cells each of which has a smaller coverage area. The sum of the coverage areas should still provide the required coverage. The number of channels per new part-cell may need to be adjusted. The required coverage and traffic handling capability is obtained by repeating the procedure from item 2. If the lowest antenna power 1û is not used in item 2, it may sometimes be sufficient to reduce the power in one or more cells for achieving a possibility of implementation.
If implementation is possible, the problem is solved for the occasion but, on the other hand, may come up again on a later occasion by replanning having to be carried out for one reason or another, possibly with further cell multiplication.
If implementation is possible, the problem is solved for the occasion but, on the other hand, may come up again on a later occasion by replanning having to be carried out for one reason or another, possibly with further cell multiplication.
8. Planning new cells or replanning existing ones.
At items 6 and 7 above, it is practical to use a plotting program wh;ch produces plots of the interference situation in a coverage area with respect to interferences from a station (downlink) or mobile unit (uplink) in a second coverage area. The plot program calculates the degree of interference and provides a visual illustration of the interference situation which results in a further accurate planning of the cell and its interaction with other cells. Plann;ng can now be carried out not only with respect to the amount of interference but also w;th regard to the overall ;nterference pattern and tak;ng ;nto account the system aspects such as hand-over boundar;es. It is possible to vary base station powers and power classes for mobile units and also to regulate the coverage individually for each cell. This can be done slmultaneously both for down- and upl;nks. It is also no longer necessary to be tied to a fixed limit value for the amount of interference but the cells can be planned indiv;dually with respect to the unique interference pattern. For example, interferences do not produce any problem with normal traffic loading in those cases where these interferences can be considered to belong to the coverage area of another cell. The : '.,'' :'- ' ' ." , ' . ' :, . ~ : :. - . : . .: . . - ~ . :, .
- , .
WO 90/10342 ~ PCr/~E90/U0130 method is work-intensive but produces a result w;th extremely high quality.
Figures 8-10 show plots of the service area of the base station in Vallingby w;th regard to interferences from the coverage area around the base station at Odenplan. The downlink situation is illustrated in Figure 8, where the limit value for coverage is -93 dBm. The coverage is produced by plotted l;ne segments, while ;nterferences from Odenplan are des;gnated by 0. The degree of ;nterference (i.e. the element in the cross-;nterference matrix) is ca(culated as 0.8%.
F;gure 9 shows a plot of a corresponding s;tuat;on for the uplink. It is thus a p;cture of how the mob;le un;ts in the coverage area of the base station at Odenplan ;nterfere w;th the base stat;on ;n V3ll;ngby. The degree of ;nterference ;s here approximately ten times greater than in the downlink which ;mplies a s;tuation wh;ch ;s not acceptable with respect to qual;ty.
f;gure 10 shows a plot of the uplink situat;on when the limit value for coverage has been increased to -88 dBm. The coverage area has been slightly reduced but the interference s;tuation has become acceptabLe w;th a degree of ;nterference of about 4~, that is to say less than half compared with Figure 9.
The Figures 8-1û thus show that it is not suff;cient only to cons;der the downlink interferences since, in the example above, the degree of interference was ten times greater in the uplink case. If th;s s;tuat;on had been allowed, the commun;cat;on ;n the uplink, that is to say from a mob;le unit to another subscr;ber, would have been d;sturb;ngly bad even ;f the commun;cation ;n the other d;rect;on had been acceptable.
Naturally, the procedure descr;bed cannot be repeated ad absurdum. When the cells are very smalL, hand-over occurs very frequently wh;ch becomes disadvantageous. When the cells have a d;ametr;c extens;on of approximately one k;lometer, the lower l;mit ;s reached and the system cannot be extended for further increased capac;ty. Naturally, ;t can occur that replann;ng is sometimes 35 carr;ed out with the intention of reducing the system capacity for a `
geographical area. The same procedure wh;ch has been described above can also be used ;n this case. A reduced est;mated traff;c demand ;n ~.
f ~. . . .
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., - ' .' . .
.
,, w~o rJo/,0342 ~ 2 7 ~ PCI/SE90~00130 this case leads to fusions of cells or cell enlargements, in which respect base stations can be taken out of operation.
According to the embodiment of the invention described here, measured field strength values have been used for constructing the S exclusion matrix. However, the invention does not exclude calculated field strength values being used if these are available. The invention is limited only by the claims below.
.
.
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.
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At items 6 and 7 above, it is practical to use a plotting program wh;ch produces plots of the interference situation in a coverage area with respect to interferences from a station (downlink) or mobile unit (uplink) in a second coverage area. The plot program calculates the degree of interference and provides a visual illustration of the interference situation which results in a further accurate planning of the cell and its interaction with other cells. Plann;ng can now be carried out not only with respect to the amount of interference but also w;th regard to the overall ;nterference pattern and tak;ng ;nto account the system aspects such as hand-over boundar;es. It is possible to vary base station powers and power classes for mobile units and also to regulate the coverage individually for each cell. This can be done slmultaneously both for down- and upl;nks. It is also no longer necessary to be tied to a fixed limit value for the amount of interference but the cells can be planned indiv;dually with respect to the unique interference pattern. For example, interferences do not produce any problem with normal traffic loading in those cases where these interferences can be considered to belong to the coverage area of another cell. The : '.,'' :'- ' ' ." , ' . ' :, . ~ : :. - . : . .: . . - ~ . :, .
- , .
WO 90/10342 ~ PCr/~E90/U0130 method is work-intensive but produces a result w;th extremely high quality.
Figures 8-10 show plots of the service area of the base station in Vallingby w;th regard to interferences from the coverage area around the base station at Odenplan. The downlink situation is illustrated in Figure 8, where the limit value for coverage is -93 dBm. The coverage is produced by plotted l;ne segments, while ;nterferences from Odenplan are des;gnated by 0. The degree of ;nterference (i.e. the element in the cross-;nterference matrix) is ca(culated as 0.8%.
F;gure 9 shows a plot of a corresponding s;tuat;on for the uplink. It is thus a p;cture of how the mob;le un;ts in the coverage area of the base station at Odenplan ;nterfere w;th the base stat;on ;n V3ll;ngby. The degree of ;nterference ;s here approximately ten times greater than in the downlink which ;mplies a s;tuation wh;ch ;s not acceptable with respect to qual;ty.
f;gure 10 shows a plot of the uplink situat;on when the limit value for coverage has been increased to -88 dBm. The coverage area has been slightly reduced but the interference s;tuation has become acceptabLe w;th a degree of ;nterference of about 4~, that is to say less than half compared with Figure 9.
The Figures 8-1û thus show that it is not suff;cient only to cons;der the downlink interferences since, in the example above, the degree of interference was ten times greater in the uplink case. If th;s s;tuat;on had been allowed, the commun;cat;on ;n the uplink, that is to say from a mob;le unit to another subscr;ber, would have been d;sturb;ngly bad even ;f the commun;cation ;n the other d;rect;on had been acceptable.
Naturally, the procedure descr;bed cannot be repeated ad absurdum. When the cells are very smalL, hand-over occurs very frequently wh;ch becomes disadvantageous. When the cells have a d;ametr;c extens;on of approximately one k;lometer, the lower l;mit ;s reached and the system cannot be extended for further increased capac;ty. Naturally, ;t can occur that replann;ng is sometimes 35 carr;ed out with the intention of reducing the system capacity for a `
geographical area. The same procedure wh;ch has been described above can also be used ;n this case. A reduced est;mated traff;c demand ;n ~.
f ~. . . .
', , ,,~ ' ' ' .
., - ' .' . .
.
,, w~o rJo/,0342 ~ 2 7 ~ PCI/SE90~00130 this case leads to fusions of cells or cell enlargements, in which respect base stations can be taken out of operation.
According to the embodiment of the invention described here, measured field strength values have been used for constructing the S exclusion matrix. However, the invention does not exclude calculated field strength values being used if these are available. The invention is limited only by the claims below.
.
.
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.
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Claims (15)
1. A method for planning radio cells, wherein a) the traffic demand is geographically estimated, b) an acceptable coverage of the traffic demand is produced with the aid of a number of cells with suitable transmitter powers and antenna arrangements, c) coverage and interference measurements are carried out for the cells, which measurement results are stored in a measurement data base, d) each cell is allocated a number of channels which corresponds to the estimated traffic demand, having regard to a margin for acceptable blocking, e) an exclusion matrix is calculated on the basis of the measurement results, which matrix represents the interaction between the cells in the system, f) an allocating algorithm is iterated, which algorithm, by utilizing a random technique, provides a random channel allocation for the cells, in which respect a collection of channel allocations is generated, which collection contains different channel allocations and by this means provides information about the possibility of implementation of the current attempt, g) if no possible channel allocation is obtained with regard to the maximum number of channels, a new attempt is made in any of the above steps.
2. The method for planning radio cells as claimed in claim 1, wherein the new attempt in step (g) means that one or more of the cells in step (b) is divided up into cells with smaller coverage areas, or that two or more of the cells in b) are combined in one single cell with a greater coverage than the coverages of the first cells.
3. The method for planning radio cells as claimed in any of the preceding claims, wherein the new attempt in g) means that one or more of the cells in b) is given a greater or smaller coverage either by respectively increasing or reducing the base station power or by changing the alarm limit value (hand-over alarm).
4. The method for planning radio cells as claimed in any of the preceding claims, wherein the new attempt in g) means that one or more of the cells in b) are given a different number of channels per cell with the aim of adapting to a situation with changed traffic demand.
5. The method as claimed in any of the preceding claims, wherein an acceptable coverage of the traffic demand is produced with the aid of an existing radio cell system, to which a number of cells has been added or from which a number of cells has been subtracted, for adapting the radio cell system to a changed traffic demand.
6. A method for constructing an exclusion matrix for planning radio cells in a radio system as claimed in any of the preceding claims comprising base stations with respective coverage areas and mobile units, in which method field strengths from all base stations are measured and/or calculated on relevant traffic routes in the geographic area of the mobile radio system, wherein a downlink matrix is formed which describes the interference ratios for transmitting base stations and receiving mobile units, each matrix element referring to the relationship between two base stations by at least one cross-interference matrix being formed by setting the matrix element Pij(LPk) = p where P is the fraction of the coverage area for which it holds true that Pi/Pj < LPk where Pj is the power received at the mobile unit from the own base, Pj is the power received at the mobile unit from an interfering base and LPk is a certain figure of merit.
7. The method as claimed in claim 6, wherein an uplink matrix is also formed which describes the interference ratios for transmitting mobile units and receiving base stations, each matrix element referring to the relationship between two base stations, and the exclusion matrix is formed as the union of the downlink matrix and uplink matrix, the union of the matrices being defined as the matrix with the union of corresponding elements and the union of two matrix elements being defined as the element which represents the strongest interference.
8. The method as claimed in claim 7, wherein the uplink matrix is formed by setting the matrix element Qij(LQk) = q where q is the fraction of the coverage area for which Qi/Q; < LQk holds true, where Qj is the power received at the base from the own mobile unit, Qj is a random interference field strength which represents the power received at the base from an interfering mobile unit, and LQk is a certain figure of merit.
9. The method as claimed in claim 8, wherein said random interference field strength values Qj are related to geographic coordinates in a respective coverage area for the interfering mobile unit, and are represented by a statistical model which describes the instantaneous position of the interfering mobile unit.
10. The method as claimed in claim 9, wherein the field strength values of the interfering mobile unit are represented in table form and a uniform selection is carried out over all values of the table.
11. The method as claimed in claim 9, wherein the field strength values of the interfering mobile unit are represented by a logarithmically normal distribution function based on the mean value or the median and the deviation of the said interference field strength values.
12. The method as claimed in claim 7, wherein the uplink matrix is formed by at least one cross-interference matrix being formed by setting the matrix element Qij(LQk) = q where q is the fraction of the coverage area for which Qi/Qjy < LQk holds true, where Qi is the power received at the base from the own mobile unit, Qjy is a power value, which, for a certain part of the coverage area of the interfering mobile unit, for example 90%, exceeds the interference power generated by the mobile unit, and LQk is a certain figure of merit.
13. The method as claimed in any of claims 6-12, wherein two cross-interference matrices are formed for each downlink matrix and uplink matrix, the figures of merit LP1 and LQ1 relating to co-channel interferences and the figures of merit LP2 and LQ2 relating to interferences of the first adjacent channel.
14. The method as claimed in claim 13 wherein the downlink matrix is formed by setting the matrix element uij = "O"; i = j uij = "A"; Pij(LP2) > px uij = "X"; Pij(LP1) > px uij = "."; Pij(LP1) ? px where px is the limit value of the degree of disabling interference for the downlink matrix, and the uplink matrix is formed by setting the matrix element vij = "O"; i = j vij = "A"; Qij(LQ2) > py vij = "X"; Qij(LQ1) > py vij = "."; Qij(LQ1) ? py where py is the limit value of the degree of disabling interference for the uplink matrix.
15. The method as claimed in claim 13 wherein the downlink matrix is formed by setting the matrix element uij = "O"; i = j uij = "A"; Pij(LP2) > px uij = "X"; Pij(LP1) > px uij = "Y"; px/2 < Pij(LP1) ? px uij = "Z"; px/4 < Pij(LP1) ? px/2 uij = "."; Pij(LP1) ? px/4 where px is the limit value of the degree of disabling interference for the downlink matrix and the uplink matrix is formed by setting the matrix element vij = "O"; i = j vij = "A"; Qij(LQ2) > py vij = "X"; Qij(LQ1) > py vij = "Y"; py/2 < Qij(LQ1) ? py vij - "Z"; py/4 < Qij(LQ1) ? py/2 vij = "."; Qij(LQ1) ? py/4 where py is the limit value of the degree of disabling interference for the uplink matrix.
Applications Claiming Priority (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8900744A SE465145B (en) | 1989-03-03 | 1989-03-03 | Method for setting up and operating a radio cell system |
| SE8900743-9 | 1989-03-03 | ||
| SE8900745A SE465247B (en) | 1989-03-03 | 1989-03-03 | Method of determining the physical interaction between the coverage areas in mobile radio systems |
| SE8900744-7 | 1989-03-03 | ||
| SE8900743A SE465246B (en) | 1989-03-03 | 1989-03-03 | Method for determining upstream interference in mobile radio systems |
| SE8900745-4 | 1989-03-03 | ||
| PCT/SE1990/000130 WO1990010342A1 (en) | 1989-03-03 | 1990-02-26 | Method for planning radio cells |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2046274A1 true CA2046274A1 (en) | 1990-09-07 |
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ID=27355483
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2046274A Abandoned CA2046274A1 (en) | 1989-03-03 | 1990-02-26 | Method for planning radio cells |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US5293640A (en) |
| EP (1) | EP0461192B1 (en) |
| JP (1) | JP2976211B2 (en) |
| AT (1) | ATE123607T1 (en) |
| AU (1) | AU627858B2 (en) |
| CA (1) | CA2046274A1 (en) |
| DE (1) | DE69019961T2 (en) |
| ES (1) | ES2072428T3 (en) |
| WO (1) | WO1990010342A1 (en) |
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1990
- 1990-02-26 EP EP90904961A patent/EP0461192B1/en not_active Expired - Lifetime
- 1990-02-26 WO PCT/SE1990/000130 patent/WO1990010342A1/en active IP Right Grant
- 1990-02-26 JP JP2505000A patent/JP2976211B2/en not_active Expired - Lifetime
- 1990-02-26 ES ES90904961T patent/ES2072428T3/en not_active Expired - Lifetime
- 1990-02-26 DE DE69019961T patent/DE69019961T2/en not_active Expired - Fee Related
- 1990-02-26 AT AT90904961T patent/ATE123607T1/en not_active IP Right Cessation
- 1990-02-26 CA CA2046274A patent/CA2046274A1/en not_active Abandoned
- 1990-02-26 US US07/752,510 patent/US5293640A/en not_active Expired - Fee Related
- 1990-02-26 AU AU52735/90A patent/AU627858B2/en not_active Ceased
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| ES2072428T3 (en) | 1995-07-16 |
| DE69019961T2 (en) | 1995-10-19 |
| EP0461192A1 (en) | 1991-12-18 |
| EP0461192B1 (en) | 1995-06-07 |
| AU627858B2 (en) | 1992-09-03 |
| DE69019961D1 (en) | 1995-07-13 |
| WO1990010342A1 (en) | 1990-09-07 |
| JP2976211B2 (en) | 1999-11-10 |
| US5293640A (en) | 1994-03-08 |
| JPH04504038A (en) | 1992-07-16 |
| ATE123607T1 (en) | 1995-06-15 |
| AU5273590A (en) | 1990-09-26 |
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