CN101483926B - Channel evaluation method and apparatus - Google Patents

Channel evaluation method and apparatus Download PDF

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CN101483926B
CN101483926B CN2009100781503A CN200910078150A CN101483926B CN 101483926 B CN101483926 B CN 101483926B CN 2009100781503 A CN2009100781503 A CN 2009100781503A CN 200910078150 A CN200910078150 A CN 200910078150A CN 101483926 B CN101483926 B CN 101483926B
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frame
channel
time
allocated channel
send
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CN101483926A (en
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邓鹏�
周国军
徐百忱
王健
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New H3C Technologies Co Ltd
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Hangzhou H3C Technologies Co Ltd
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Abstract

The present invention discloses a channel evaluating method which includes: employing the time required by an appointed channel for sending preset amount data frame in the appointed channel without channel competition; each device requiring channel competition; sending data frame in the appointed channel in the obtained time and recording the sent data frame amount; using ratio of the sent data frame amount to the preset amount as a leisure index of the appointed channel; and selecting a standard channel according to the free/busy index of a plurality of appointed channel. The present invention also discloses a channel evaluating device and another channel evaluating method. The technique scheme provided by the present invention can evaluate channel rapidly and accurately.

Description

Channel evaluation method and device
Technical field
The present invention relates to wireless communication technology field, refer to channel evaluation method and device especially.
Background technology
IEEE 802.11 agreements are medium access control (MAC) layer protocols, specified in more detail node visit transmission medium and the basic agreement that do not bump.IEEE 802.11 supports two kinds of different MAC layer mechanism: first kind is distributed coordination function (DCF, Distributed Coordination Function), support simultaneous asynchronous data transmissions business, all users that will transmit data have the chance of equal access network; Second kind is point coordination function (PCF, Point Coordination Function), is mainly used in transmitting real-time service.
DCF is a kind of access control mechanisms of wireless network to shared channel, its core is that (CSMA/CA is avoided in the access/conflict of carrier sense multiple access, Carrier Sense Multiple Access/CollisionAvoidance) technology, comprise: carrier sense mechanism, interFrameGap (IFS, Inter Frame Space) and random back (random back off) mechanism.
DCF provides two kinds of working methods, and a kind of is the CSMA/CA fundamental mode; Another kind is that request transmission/permission sends (RTS/CTS, Request To Send/Clear To Send) protocol mode.
The workflow of CSMA/CA is: data receiver A starts CSMA/CA mechanism, monitor channel at first, if idle time of channel is greater than distributed coordination function interFrameGap (DIFS, DCF InterFrame Space), then select the random back time (Back Off Time) to enter backoff procedure, keep out of the way and finish back transmission Frame; Otherwise, postpone to insert until the free time that detects channel greater than DIFS, select a random back time to enter backoff procedure then, keep out of the way and finish the back and send Frame; Data receiver A waits for the acknowledgement frame (ACK) that recipient B returns after sending data, if do not receive the ACK that B returns, then needs to resend Frame.
The workflow of RTS/CTS is: A sends the RTS signal to B when listening to idle time of channel greater than DIFS, show that A will send plurality of data to B, after B receives RTS, send cts signal to all base stations, show ready, A can send, and all the other desire then to suspend transmission to the base station of B transmission data; Both sides just begin real data passes after successfully exchanging RTS/CTS signal (promptly finish and shake hands), guaranteed that a plurality of mutual sightless transmission websites are simultaneously when same receiving station sends signal, actual can only be that website of receiving receiving station response CTS can send, and has avoided conflict to take place.
Present channel estimating scheme generally all is to adopt above-mentioned listening mode to judge the busy not busy probability of channel.But adopt the mode of monitoring channel to be assessed not comprehensive, for example, current channel has A, B and three equipment of C in competition, equipment D prepares to add the competition of channel, if equipment D only adopts the mode of monitoring, then device A, B and C perception can not reflect the situation of seizing of channel when A, B, C and four equipment of D will send packet simultaneously fully less than the existence of competitor D.Therefore need a kind of new channel evaluation method more accurately.
Summary of the invention
The invention provides a kind of channel evaluation method, this method can be assessed channel quickly and accurately.
The present invention also provides a kind of channel estimating device, and this device can be assessed channel quickly and accurately.
The present invention also provides a kind of channel evaluation method, and this method can be assessed channel exactly.
For achieving the above object, technical scheme of the present invention specifically is achieved in that
The invention discloses a kind of channel evaluation method, this method comprises:
Obtain allocated channel and when no channel competition, on this allocated channel, send the predetermined quantity required time of Frame;
Each wants the equipment of competitive channel to send Frame on described allocated channel in the described time of obtaining, and the quantity of the record Frame that sends;
With the ratio of the quantity of described transmission Frame and described predetermined quantity busy not busy index, according to the busy not busy index selective channel of a plurality of allocated channels as described allocated channel;
Wherein,
The Frame send mode is the broadcast data frame mode;
The described allocated channel that obtains sends the predetermined quantity required time of Frame and is on this allocated channel when no channel competition:
To distributed coordination function interFrameGap DIFS time, the back off time of selecting when sending a Frame with send a required time of Frame according to the agreement regulation and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame;
Perhaps,
The Frame send mode is for needing the mode of opposite end feedback acknowledgment frame ACK after sending Frame;
The described allocated channel that obtains sends the predetermined quantity required time of Frame and is on this allocated channel when no channel competition:
To DIFS time, the back off time of selecting when sending a Frame, send required time of Frame, time that Frame transmits, opposite equip. according to the agreement regulation in allocated channel and send the time that required time of acknowledgement frame and acknowledgement frame transmit according to the agreement regulation in allocated channel and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame.
The invention also discloses a kind of channel estimating device, this device comprises: acquisition module, and sending module and evaluation module, wherein,
The mode that sends Frame is the Frame mode;
Acquisition module, be used for distributed coordination function interFrameGap DIFS time, the back off time of selecting when sending a Frame and send a required time of Frame suing for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel according to the agreement regulation; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame, and the described time value of obtaining sent to sending module, described predetermined number value is sent to evaluation module;
Perhaps,
The Frame send mode is for needing the mode of opposite end feedback acknowledgment frame ACK after sending Frame;
Acquisition module, be used for DIFS time, the back off time of selecting when sending a Frame, send required time of Frame, Frame according to the agreement regulation and send the time that required time of acknowledgement frame and acknowledgement frame transmit in time that allocated channel transmits, opposite equip. according to the agreement regulation in allocated channel and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame, and the described time value of obtaining sent to sending module, described predetermined quantitative value is sent to evaluation module;
Sending module was used for sending Frame on described allocated channel in the described time of obtaining, the quantity of the record Frame that sends, and the quantity of the transmission Frame that write down sent to evaluation module;
Evaluation module is used for the ratio of the quantity of described transmission Frame and the described predetermined number value busy not busy index as described allocated channel, and each wants the equipment of competitive channel, according to the busy not busy index selective channel of a plurality of allocated channels.
The invention also discloses a kind of channel evaluation method, this method comprises:
Obtain allocated channel and when no channel competition, adopt the broadcast data frame mode on this allocated channel, to send the required time of Frame of predetermined quantity, be labeled as the very first time;
Each wants the equipment of competitive channel to send Frame on described allocated channel, and the required time of Frame of the described predetermined quantity of record transmission, is labeled as for second time;
With the ratio of the described very first time and second time busy not busy index, according to the busy not busy index selective channel of a plurality of allocated channels as described allocated channel;
Wherein,
The mode that sends Frame is the Frame mode;
The described allocated channel that obtains sends the predetermined quantity required time of Frame and is on this allocated channel when no channel competition:
To DIFS time, the back off time of selecting when sending a Frame with send a required time of Frame according to the agreement regulation and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame;
Perhaps,
The Frame send mode is for needing the mode of opposite end feedback acknowledgment frame ACK after sending Frame;
The described allocated channel that obtains sends the predetermined quantity required time of Frame and is on this allocated channel when no channel competition:
To DIFS time, the back off time of selecting when sending a Frame, send required time of Frame, time that Frame transmits, opposite equip. according to the agreement regulation in allocated channel and send the time that required time of acknowledgement frame and acknowledgement frame transmit according to the agreement regulation in allocated channel and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame.
As seen from the above technical solution, this allocated channel that obtains of the present invention sends the predetermined quantity required time of Frame on this allocated channel when no channel competition, in the described time of obtaining, on described allocated channel, send Frame, and the quantity of the record Frame that sends, in the technical scheme of ratio with the quantity of described transmission Frame and described predetermined quantity as the busy not busy index of described allocated channel, each equipment of wanting competitive channel is when the busy idle condition of a channel of assessment, can on this channel, send the Frame of some, this is for the equipment of wanting competitive channel of the prior art is just merely monitored, the actual state of channel is user's race condition of closing to reality more, and the not busy index of therefore resulting channel busy can embody the actual race condition of channel more accurately.
Description of drawings
Fig. 1 is the flow chart of a kind of channel evaluation method of the embodiment of the invention;
Fig. 2 is IEEE 802.11 common MAC frame format schematic diagrames;
Fig. 3 is the short PLCP physical layer protocol data unit of an IEEE 802.11b frame format schematic diagram;
Fig. 4 is the transmission course schematic diagram of broadcast data frame among the present invention;
Fig. 5 is an IEEE802.11a OFDM PLCP frame format schematic diagram;
Fig. 6 is the composition structured flowchart of a kind of channel estimating device of the embodiment of the invention.
Embodiment
Fig. 1 is the flow chart of a kind of channel evaluation method of the embodiment of the invention.As shown in Figure 1, this method may further comprise the steps:
Step 101 is obtained allocated channel and send the predetermined quantity required time of Frame when no channel competition on this allocated channel.
Step 102 sends Frame on described allocated channel in the described time of obtaining, and the quantity of the record Frame that sends.
Step 103 is with the ratio of the quantity of described transmission Frame and the described predetermined quantity busy not busy index as described allocated channel.
According to the described scheme of Fig. 1, each equipment of wanting competitive channel is when the busy idle condition of a channel of assessment, can on this channel, send the Frame of some, this is for the equipment of wanting competitive channel of the prior art is just merely monitored, the actual state of channel is user's race condition of closing to reality more, therefore can embody the actual race condition of channel more accurately according to the not busy index of the resulting channel busy of the described scheme of Fig. 1.
According to the described scheme of Fig. 1, obtain the busy not busy index of a plurality of channels after, can select a less channel of competition relatively according to the busy not busy index of each channel, thereby avoid interference.It is present that this electromagnetic environment at wireless system becomes increasingly complex, and helps the user and carrying out understanding current electromagnetic environment quickly and easily when wlan network is disposed, and guides user is to the selection of channel.
In scheme shown in Figure 1, in the identical time, when channel is in uncompetitive perfect condition and actual time of day the ratio of the number of data frames that can send as the index of this channel busy-idle condition of assessment.Simultaneously, the present inventor has also expected when sending the Frame of equal number, the ratio of required time was as the index of this channel busy-idle condition of assessment when channel was in uncompetitive perfect condition and actual time of day, be specially: obtain allocated channel sends predetermined quantity on this allocated channel when no channel competition the required time of Frame, be labeled as the very first time; On described allocated channel, send Frame, and the required time of Frame of the described predetermined quantity of record transmission, be labeled as for second time; With the ratio of the described very first time and second time busy not busy index as described allocated channel.
But the latter need send the Frame of predetermined quantity on actual channel, and very poor when the actual state of channel, promptly during dog-eat-dog, the Frame that sends predetermined quantity needs long time.Therefore this scheme is not high with respect to the former time efficiency.In following embodiment, all the former (scheme shown in Figure 1) is further detailed.
Current, there are 13 channels available on the 2.4GHz frequency range, be respectively ch1~Ch13, and the channel on the 5GHz frequency range has: ch34~ch64, ch100~chi40, ch149~ch165.Be example with the channel on 2.4GHz frequency range and the 5GHz frequency range below, the described scheme of Fig. 1 is further specified.
One, the channel estimating on the 2.4GHz frequency range
Can encapsulate for the data M AC layer from the upper strata, Fig. 2 is IEEE 802.11 common MAC frame format schematic diagrames.As shown in Figure 2, the mac frame head comprises: frame control (Frame Control) field, the duration/sign (Duration/ID) field, address 1 (Addressl) field, address 2 (Address2) field, address 3 (Address3) field, order control (Sequence Control) field, address 1 (Addressl) field; Wherein, frame control field comprises again: protocol version (Protocol Version) field, Lei Xing ﹠amp; Subtype (Type﹠amp; Subtype) field, purpose DS field, source DS field, many fragments (Morefrag) field, retry (Retry) field, energy control (Power manage) field, more (More) field, WEP Fields and order (Order) field.
Mac frame can hand down and be delivered to physical layer, and the convergence sub-layer (PLCP by physical layer, PhysicalLayer Convergence Procedure) carries out necessary processing and encapsulation, be specially and add PLCP lead code and PLCP header between the management level (PMD) of MAC layer and physical layer so that data are transmitted.Direct and the physical medium interface of pmd layer is the transceiver of wireless messages.
IEEE 802.11b carrier frequency is 2.4GHz.Fig. 3 is the short PLCP physical layer protocol data unit of an IEEE 802.11b frame format schematic diagram.As shown in Figure 3, lacking PLCP physical layer protocol data unit (PPDU) frame comprises: the short PLCP lead code of 72 bits, the short PLCP header of 48 bits and mac-layer protocol data cell (MPDU).Here MPDU is mac frame shown in Figure 2.Wherein, the short PLCP lead code of 72 bits comprises: the weak point of 56 bits is the SFD of (SYNC), 16 bits synchronously; The short PLCP header of 48 bits comprises: the service (SERVICE) of the signal of 8 bits (SIGNAL), 8 bits, the length (LENGTH) of 16 bits and the CRC check sign indicating number of 16 bits.Stipulate among the IEEE 802.11b that the transmission rate of short PLCP lead code is 1Mbps, the transmission rate of short PLCP header is 2Mbps, and the transmission rate of MPDU can change, and for example transmits with speed such as 2Mbps, 5.5Mbps or 11Mbps.
The physical layer protocol of IEEE 802.11g is defined in the 2.4GHz frequency range, uses OFDM (OFDM) technology, and message transmission rate reaches as high as 54Mbps.IEEE 802.11g can use different modulation systems to lead code, header and the data field MPDU of PPDU frame, comprise: OFDM/OFDM mode and CCK/OFDM mode, wherein CCK is meant complementary code keying (Complementary Code Keying) modulation system.
Wherein, the OFDM/OFDM mode is all to use the OFDM modulation system to transmit to lead code, header and data field, and the available data rate of OFDM has: 6Mbps, 9Mbps, 12Mbps, 18Mbps, 24Mbps, 36Mbps, 48Mbps and 54Mbps.Because OFDM can not provide 1Mbps and 2Mbps (lead code of stipulating among the IEEE802.11b and the transmission rate of header), so the OFDM/OFDM mode can't realize the backward compatibility with 802.11b.
The CCK/OFDM mode is a kind of compound modulation, lead code and header are used the transmission of CCK modulation system, and data field uses the transmission of OFDM modulation system, has so just realized the backward compatibility with IEEE802.11b.CCK supports the speed of 1Mbps, 2Mbps, 5.5Mbps and 11Mbps, and the available data rate of OFDM has: 6Mbps, 9Mbps, 12Mbps, 18Mbps, 24Mbps, 36Mbps, 48Mbps and 54Mbps.
Consider and select short PLCP lead code form shown in Figure 3 in the compatible embodiment of the invention with IEEE802.11b, and employing CCK/OFDM modulation system describes scheme shown in Figure 1.
In scheme shown in Figure 1, relate to the problem that how on channel, sends Frame, be example with two kinds of Frame send modes in the present embodiment.In first kind of Frame send mode, only consider the situation of broadcast data frame, need not opposite end feedback acknowledgment frame (ACK) when promptly on channel, sending Frame.In second kind of Frame send mode, then after sending Frame on the channel, need opposite end feedback AKC.Describe respectively below.
Fig. 4 is the transmission course schematic diagram of broadcast data frame among the present invention.Figure is shown in 4, send the equipment monitor channel of data, when free time that listens to channel during greater than distributed coordination function interFrameGap DIFS, select a back off time (Backoff Time) to enter backoff procedure, back off time is one and competition window (CW, Contention Window) relevant value, backoff procedure finish the back and send a Frame on channels, and the step of returning described monitor channel is ready for sending next Frame.
Then selecting short PLCP lead code form shown in Figure 3, adopt the CCK/OFDM modulation system that the PPDU frame is transmitted, and when only considering broadcast data frame, under the situation of no channel competition: the needed time T 1 of broadcast frame that on the channel of 2.4GHz frequency range, sends the individual IEEE802.11g 54Mbps of n (natural number arbitrarily) as shown in Equation (1):
T1=n * DIFS+BackoffTime+ (72bit/1Mbps)+(48bit/2Mbps)+(the MPDU frame length/54Mbps) } (1)
Wherein, DIFS is the DCF interFrameGap, if channel is in idle condition during this period, then at this moment explanation can send Frame and seize channel;
Backoff Time is a back off time, and Backoff Time=INT (CW * Random) * SlotTime; Wherein, INT represents to round, and CW is the length of competition window, and value is CW MinAnd CW MaxBetween an integer, the minimum value CW of CW MinCan preestablish, and maximum CW MaxCan preestablish also and can not do qualification; When all frames sent for the first time, the initial value of CW can be got CW Min, CW doubles until CW during each later on the re-transmission MaxRandom is between 0 to 1 one decimal at random; Slot Time is a slot length;
72bit/1Mbps represents that the short PLCP lead code of 72 bits is with the required time of 1Mbps speed rates;
48bit/2Mbps represents that the short PLCP header of 48 bits is with the required time of 2Mbps speed rates;
MPDU frame length/54Mbps represents that Frame adopts the 54Mbps required time of speed rates; Certainly the transmission rate of Frame can be other values according to actual conditions also, as 36Mbps, 48Mbps etc., is example with 54Mbps just here.
After obtaining T1,, on channel, send Frame in the time at T1 according to step 102, and the quantity of the record Frame that sends, here be assumed to be m1, then m1/n promptly represents the probability that the packet of this channel successfully transmits, and can use the busy not busy index of m1/n as this channel.
In second kind of Frame send mode, after sending Frame on the channel, need opposite end feedback AKC, concrete data transmission procedure is as follows: equipment monitor channel that the invention data, when free time that listens to channel during greater than DIFS, select a back off time to enter backoff procedure, backoff procedure finishes the back and send a Frame on channel, wait for opposite end feedback acknowledgment frame then, if receive the acknowledgement frame that the channel opposite equip. returns at the appointed time, the step of then returning described monitor channel is ready for sending next Frame, otherwise resends current data frame and carry out the step of described wait opposite end feedback data frame.
Then selecting short PLCP lead code form shown in Figure 3, adopt the CCK/OFDM modulation system that the PPDU frame is transmitted, and when adopting the mode of opposite end feeding back ACK, under the situation of no channel competition: the needed time T 2 of broadcast frame that sends the individual IEEE802.11g 54Mbps of n (arbitrarily natural number) on the channel of 2.4GHz frequency range need send the required time of ACK to signal and take into account in the propagation delay in space and opposite end, T2 as shown in Equation (2):
T2=n * DIFS+Backoff Time+ (72bit/1Mbps)+(48bit/2Mbps)+(the MPDU frame length/54Mbps)+2derta+SIFS+T ACK(3)
Wherein, derta is the propagation delay of signal in the space, derta=communication distance 1/c, and c is the light velocity=3 * 10 8M/s, therefore the Frame that consideration sends and the time-delay of ACK frame multiply by 2;
SIFS is that the opposite end receives Frame to the time that begins to send between the ACK frame;
T ACKFor the opposite end sends the ACK required time of frame, when the ACK frame adopts IEEE802.11b or the encapsulation of IEEE802.11g physical layer, T ACK=(72bit/1Mbps)+(48bit/2Mbps)+(112bit/R);
After obtaining T2,, on channel, send Frame in the time at T2 according to step 102, and the quantity of the record Frame that sends, here be assumed to be m2, then m2/n promptly represents the probability that the packet of this channel successfully transmits, and can use the busy not busy index of m2/n as this channel.
Two, the channel estimating on the 5GHz frequency range
In the prior art, can only send the 802.11a frame on the 5GHz frequency range, and the 802.11a frame on the 5GHz do not have the CCK modulation system, can only adopt the OFDM/OFDM modulation system.Fig. 5 is an IEEE802.11aOFDM PLCP frame format schematic diagram.Referring to Fig. 5, in the 802.11a frame on the 5GHz, the PLCP preamble field is used for realizing synchronously, is made up of 10 Short Training symbols and 2 long training symbols, and total training time is 16us.Signal field in the PLCP header (signal field comprises the speed field of 4 bits, the reserved field of 1 bit, the length field of 12 bits, the parity fields of 1 bit and the tail tag field of 6 bits) sends (being 6Mbps) with reliable two-phase PSK BPSK modulation and 1/2 encoding rate.The SERVICE field of 16 bits of PLCP message is added the tail tag field of 6 bits and is filled field as data field with PSDU, and sends with the speed of indicating in the speed field.
Then selecting PLCP lead code form, adopt the OFDM/OFDM modulation system that the PPDU frame is transmitted, and when only considering broadcast data frame, under the situation of no channel competition: the needed time T 3 of broadcast frame that on the channel of 5GHz frequency range, sends n IEEE802.11a 54Mbps as shown in Equation (1):
T3=n * DIFS+Backoff Time+16us+ (24bit/6Mbps)+((16bit+MPDU frame length+6bit+ filler)/54Mbps) } (3)
Wherein, 16us represents the time of OFDM PLCP lead code symbol, also is lock in time;
24bit/6Mbps represents that the 24bit of OFDM PLCP header signal field transmits required time with 6Mbps;
(16bit+MPDU frame length+6bit+ filler)/54Mbps represents the SERVICE field of PLCP message and tail tag field and filling field that PSDU adds 6 bits, with MPDU and 54Mbps transmission required time.
After obtaining T3,, on channel, send Frame in the time at T3 according to step 102, and the quantity of the record Frame that sends, here be assumed to be m3, then m3/n promptly represents the probability that the packet of this channel successfully transmits, and can use the busy not busy index of m3/n as this channel.
Selecting PLCP lead code form, adopt the OFDM/OFDM modulation system that the PPDU frame is transmitted, and when adopting the mode of opposite end feeding back ACK, under the situation of no channel competition: the needed time T 4 of broadcast frame that sends n IEEE802.11a 54Mbps on the channel of 5GHz frequency range need be taken signal into account in the propagation delay and the opposite end transmission required time of ACK in space, T4 as shown in Equation (4):
T4=n * { DIFS+Backoff Time+16us+ (24bit/6Mbps)+((16bit+MPDU frame length+6bit+ filler)/54Mbps)+2derta+SIFS+T ACK(4)
Wherein, T when the ACK frame adopts the encapsulation of IEEE 802.11a physical layer ACK=16us+ (24bit/6Mbps)+((16bit+112bit+ filler)/R);
After obtaining T4,, on channel, send Frame in the time at T4 according to step 102, and the quantity of the record Frame that sends, here be assumed to be m4, then m4/n promptly represents the probability that the packet of this channel successfully transmits, and can use the busy not busy index of m4/n as this channel.
As seen, in the above embodiment of the present invention, utilize the CSMA/CA multi-user access operation principle of IEEE802.11 standard, realized channel estimating fast, accurately, improved the accuracy of wireless network planning and optimization.And in the scheme of the foregoing description, having adopted the mode of simulation practical communication process, considered the influence that WiFI signal and non-WiFI signal disturb, is that the channel estimating result is more near actual environment.
Fig. 6 is the composition structured flowchart of a kind of channel estimating device of the embodiment of the invention.As shown in Figure 6, this device comprises: acquisition module 601, and sending module 602 and evaluation module 603, wherein,
Acquisition module 601, be used to obtain allocated channel and when no channel competition, on this allocated channel, send the predetermined quantity required time of Frame, and the described time value of obtaining sent to sending module 602, described predetermined quantitative value is sent to evaluation module 603;
Sending module 602 was used for sending Frame on described allocated channel in the described time of obtaining, the quantity of the record Frame that sends, and the quantity of the transmission Frame that write down sent to evaluation module 603;
Evaluation module 603 is used for the busy not busy index of the ratio of the quantity of described transmission Frame and described predetermined quantity as described allocated channel.
In Fig. 6, sending module 602, be used to monitor described allocated channel, when free time that listens to described allocated channel during greater than distributed coordination function interFrameGap DIFS, select a back off time to enter backoff procedure, backoff procedure finishes the back and send a Frame on described allocated channel, and the step of returning described monitoring allocated channel is ready for sending next Frame.
Acquisition module 601, be used for IDFS time, the back off time of selecting when sending a Frame and send a required time of Frame suing for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel according to the agreement regulation; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame.
In Fig. 6, sending module 602, be used to monitor described allocated channel, when free time that listens to described allocated channel during greater than distributed coordination function interFrameGap DIFS, select a back off time to enter backoff procedure, backoff procedure finishes the back and send a Frame on described allocated channel, wait for the opposite equip. feedback acknowledgment frame of described allocated channel then, if receive the acknowledgement frame that the opposite equip. of described allocated channel returns at the appointed time, the step of then returning described monitoring allocated channel is ready for sending next Frame; Otherwise resend current data frame and wait for the opposite equip. feedback acknowledgment frame of described allocated channel.
Acquisition module 601, be used for IDFS time, the back off time of selecting when sending a Frame, send required time of Frame, Frame according to the agreement regulation and send the time that required time of acknowledgement frame and acknowledgement frame transmit in time that allocated channel transmits, opposite equip. according to the agreement regulation in allocated channel and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame.
In sum, this allocated channel that obtains of the present invention sends the predetermined quantity required time of Frame on this allocated channel when no channel competition, in the described time of obtaining, on described allocated channel, send Frame, and the quantity of the record Frame that sends, in the technical scheme of ratio with the quantity of described transmission Frame and described predetermined quantity as the busy not busy index of described allocated channel, each equipment of wanting competitive channel is when the busy idle condition of a channel of assessment, can on this channel, send the Frame of some, this is for the equipment of wanting competitive channel of the prior art is just merely monitored, the actual state of channel is user's race condition of closing to reality more, and the not busy index of therefore resulting channel busy can embody the actual race condition of channel more accurately.
The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention, all any modifications of being made within the spirit and principles in the present invention, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (7)

1. a channel evaluation method is characterized in that, this method comprises:
Obtain allocated channel and when no channel competition, on this allocated channel, send the predetermined quantity required time of Frame;
Each wants the equipment of competitive channel to send Frame on described allocated channel in the described time of obtaining, and the quantity of the record Frame that sends;
With the ratio of the quantity of described transmission Frame and described predetermined quantity busy not busy index, according to the busy not busy index selective channel of a plurality of allocated channels as described allocated channel;
Wherein,
The Frame send mode is the broadcast data frame mode;
The described allocated channel that obtains sends the predetermined quantity required time of Frame and is on this allocated channel when no channel competition:
To distributed coordination function interFrameGap DIFS time, the back off time of selecting when sending a Frame with send a required time of Frame according to the agreement regulation and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame;
Perhaps,
The Frame send mode is for needing the mode of opposite end feedback acknowledgment frame ACK after sending Frame;
The described allocated channel that obtains sends the predetermined quantity required time of Frame and is on this allocated channel when no channel competition:
To DIFS time, the back off time of selecting when sending a Frame, send required time of Frame, time that Frame transmits, opposite equip. according to the agreement regulation in allocated channel and send the time that required time of acknowledgement frame and acknowledgement frame transmit according to the agreement regulation in allocated channel and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame.
2. the method for claim 1 is characterized in that, when described Frame send mode is the broadcast data frame mode, sends Frame and comprise on described allocated channel:
Steps A, monitor described allocated channel;
Step B, when free time that listens to described allocated channel during greater than distributed coordination function interFrameGap DIFS, select a back off time to enter backoff procedure, backoff procedure finishes the back and send a Frame on described allocated channel, and returns steps A.
3. the method for claim 1 is characterized in that, described Frame send mode is when needing the mode of opposite end feedback acknowledgment frame ACK after sending Frame, sends Frame and comprise on described allocated channel:
Steps A, monitor described allocated channel;
Step B, whenever free time that listens to described allocated channel during greater than distributed coordination function interFrameGap DIFS, select a back off time to enter backoff procedure, backoff procedure finishes the back and send a Frame on described allocated channel;
If step C receives the acknowledgement frame that described allocated channel opposite equip. returns at the appointed time, then return steps A; Otherwise resend Frame and re-execute this step C.
4. a channel estimating device is characterized in that, this device comprises: acquisition module, and sending module and evaluation module, wherein,
The mode that sends Frame is the Frame mode;
Acquisition module, be used for distributed coordination function interFrameGap DIFS time, the back off time of selecting when sending a Frame and send a required time of Frame suing for peace, obtain when no channel competition time that Frame is required of transmission on allocated channel according to the agreement regulation; Required time of Frame of the described transmission that obtains be multiply by predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame; And on described allocated channel, send the required time value of predetermined quantity Frame during with the described no channel competition that obtains and send to sending module, described predetermined number value is sent to evaluation module;
Perhaps,
The Frame send mode is for needing the mode of opposite end feedback acknowledgment frame ACK after sending Frame;
Acquisition module, be used for DIFS time, the back off time of selecting when sending a Frame, send required time of Frame, Frame according to the agreement regulation and send the time that required time of acknowledgement frame and acknowledgement frame transmit in time that allocated channel transmits, opposite equip. according to the agreement regulation in allocated channel and sue for peace, obtain when no channel competition time that Frame is required of transmission on allocated channel; Required time of Frame of the described transmission that obtains be multiply by predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame; And on described allocated channel, send the required time value of predetermined quantity Frame during with the described no channel competition that obtains and send to sending module, described predetermined number value is sent to evaluation module;
Sending module, be used for when no channel competition, on described allocated channel, sending the predetermined quantity Frame and on described allocated channel, send Frame in the required time, the quantity of the record Frame that sends, and the quantity of the transmission Frame that write down sent to evaluation module;
Evaluation module is used for the ratio of the quantity of described transmission Frame and the described predetermined number value busy not busy index as described allocated channel, and each wants the equipment of competitive channel, according to the busy not busy index selective channel of a plurality of allocated channels.
5. device as claimed in claim 4 is characterized in that,
The mode of described transmission Frame is the Frame mode;
Described sending module, be used to monitor described allocated channel, when free time that listens to described allocated channel during greater than distributed coordination function interFrameGap DIFS, select a back off time to enter backoff procedure, backoff procedure finishes the back and send a Frame on described allocated channel, and the step of returning described monitoring allocated channel is ready for sending next Frame.
6. device as claimed in claim 4 is characterized in that,
Described Frame send mode is for needing the mode of opposite end feedback acknowledgment frame ACK after sending Frame;
Described sending module, be used to monitor described allocated channel, when free time that listens to described allocated channel during greater than distributed coordination function interFrameGap DIFS, select a back off time to enter backoff procedure, backoff procedure finishes the back and send a Frame on described allocated channel, wait for the opposite equip. feedback acknowledgment frame of described allocated channel then, if receive the acknowledgement frame that the opposite equip. of described allocated channel returns at the appointed time, the step of then returning described monitoring allocated channel is ready for sending next Frame; Otherwise resend current data frame and wait for the opposite equip. feedback acknowledgment frame of described allocated channel.
7. a channel evaluation method is characterized in that, this method comprises:
Obtain allocated channel and when no channel competition, adopt the broadcast data frame mode on this allocated channel, to send the required time of Frame of predetermined quantity, be labeled as the very first time;
Each wants the equipment of competitive channel to send Frame on described allocated channel, and the required time of Frame of the described predetermined quantity of record transmission, is labeled as for second time;
With the ratio of the described very first time and second time busy not busy index, according to the busy not busy index selective channel of a plurality of allocated channels as described allocated channel;
Wherein,
The mode that sends Frame is the Frame mode;
The described allocated channel that obtains sends the predetermined quantity required time of Frame and is on this allocated channel when no channel competition:
To distributed coordination function interFrameGap DIFS time, the back off time of selecting when sending a Frame with send a required time of Frame according to the agreement regulation and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame;
Perhaps,
The Frame send mode is for needing the mode of opposite end feedback acknowledgment frame ACK after sending Frame;
The described allocated channel that obtains sends the predetermined quantity required time of Frame and is on this allocated channel when no channel competition:
To DIFS time, the back off time of selecting when sending a Frame, send required time of Frame, time that Frame transmits, opposite equip. according to the agreement regulation in allocated channel and send the time that required time of acknowledgement frame and acknowledgement frame transmit according to the agreement regulation in allocated channel and sue for peace, obtain when no channel competition time that Frame is required of transmission on described allocated channel; Required time of Frame of the described transmission that obtains be multiply by described predetermined quantity, obtain when no channel competition, on described allocated channel, sending the predetermined quantity required time of Frame.
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