WO2007100442A2 - Predicting future changes to strenths of paths in mimo systems - Google Patents
Predicting future changes to strenths of paths in mimo systems Download PDFInfo
- Publication number
- WO2007100442A2 WO2007100442A2 PCT/US2007/002889 US2007002889W WO2007100442A2 WO 2007100442 A2 WO2007100442 A2 WO 2007100442A2 US 2007002889 W US2007002889 W US 2007002889W WO 2007100442 A2 WO2007100442 A2 WO 2007100442A2
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- WO
- WIPO (PCT)
- Prior art keywords
- history
- strength
- transmission path
- wireless node
- subsystem
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/373—Predicting channel quality or other radio frequency [RF] parameters
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/20—Monitoring; Testing of receivers
- H04B17/26—Monitoring; Testing of receivers using historical data, averaging values or statistics
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
Definitions
- Embodiments of the invention relates to a wireless communications, and more particularly to transmitting and receiving of wireless signals by wireless devices.
- Wireless devices such as cell phones, wireless routers and radio operated devices are in widespread use today. Wireless devices enable the users to receive and transmit signals without the need for a physical connection between transmitters and receivers. This lack of physical connection increases the mobility of the wireless devices, and also decreases the overhead and inconveniences associated with use of wires, cables and other physical medium for establishing communication between two devices.
- wireless devices are not without shortcomings.
- One such shortcoming is that the transmission paths between wireless nodes in a system, such as a multi-input multi-output (MIMO) system, can be unreliable.
- MIMO multi-input multi-output
- fading and shadowing amongst other factors can cause the wireless signal, and hence the corresponding data rate of the transmitted signal, to vary depending on certain events.
- One such event is the presence of animate and inanimate objects in the environment, which may cause the quality of the data transmission to vary over space and time.
- the variation and lack of reliability in data transmission may cause problems for multimedia streaming applications since sudden decreases in transmission path capacity may cause noticeable artifacts to occur during display or playback of the multimedia stream.
- An embodiment of the invention can be regarded as a method of maintaini a first history of strength of a first transmission path between a first wireless node and second wireless node in a multiple input multiple output (MIMO) communication system, maintaining a second history of strength of a second transmission path betwee third wireless node and the second wireless node in the MIMO communication systerr performing a spatiotemporal correlation between the first history and the second histoi to determine if any changes in the strength of the first transmission path is observed, ai predicting future changes to strength of the second transmission path between the third wireless node and the second wireless node based on the performed spatiotemporal correlation between the first history and the second history.
- MIMO multiple input multiple output
- Another embodiment of the invention can also be regarded as a system whi ⁇ includes a memory to maintain a first history of strength of a first transmission path between a first wireless node and a second wireless node in a multiple input multiple output (MIMO) communication system, and to maintain a second history of strength of second transmission path between a third wireless node and the second wireless node in the MEvIO communication system, a spatiotemporal correlation logic to perform a spatiotemporal correlation between the first history and the second history to determine my changes in the strength of the first transmission path is observed, and a predictor ogic to predict future changes to strength of the second transmission path between the hird wireless node and the second wireless node based on the performed spatiotemporal iorrelation between the first history and the second history.
- MIMO multiple input multiple output
- Another embodiment of the invention can also be regarded as a machine accessible medium having instructions stored thereon that, when executed by a computing device, will cause the computing device to perform the following ⁇ peratior maintain a first history of strength of a first transmission path between a first wireless node and a second wireless node in a multiple input multiple output (MIMO) communication system, maintain a second history of strength of a second transmission path between a third wireless node and the second wireless node in the MIMO communication system, perform a spatiotemporal correlation between the first history and the second history to determine if any changes in the strength of the first transmission path is observed, and predict future changes to strength of the second transmission path between the third wireless node and the second wireless node based ⁇ the performed spatiotemporal correlation between the first history and the second histo
- MIMO multiple input multiple output
- FIG. 1 is a block diagram of simplified wireless networks in which embodiments of the invention may be practiced.
- FIG. 2 is a graph of strengths of transmission paths over time in the wireless network of FIG. 1.
- FIG.3 is a flow chart of a method for an embodiment of the. invention.
- FIG.4 is a graph of the temporal correlation between the strengths of transmission paths shown in FIG. 1.
- FIG.5 is another flow chart of another method for an embodiment of the invention.
- FIG. 6 is a block diagram of a more complex wireless networks in which embodiments of the invention may be practiced.
- Embodiments of the invention generally relate to a system and method for predicting future changes to strengths of paths in multiple input multiple output (MIMO) communication systems.
- MIMO multiple input multiple output
- embodiments of the invention may be applicable to MIMO transmitters and receivers used in a variety of wireless devices. These wireless devices may be stationary or portable. Examples of wireless devices include, but are not limited or restricted to the following: cell phones, pagers, personal digital assistants (PDA), portable computers, handheld video game devices, routers and radio operated devices.
- PDA personal digital assistants
- multi-input multi-output includes any device which employs multiple antennas for simultaneously transmitting or receiving the same data from the multiple antennas.
- software generally denotes executable code such as an operating system, an application, an applet, a routine or even one or more instructions.
- the software may be stored in any type of memory, namely suitable storage medium such as a programmable electronic circuit, a semiconductor memory device, a volatile memory (e.g., random access memory, etc.), a nonvolatile memory (e.g., read-only memory, flash memory, etc.), a floppy diskette, an optical disk (e.g., compact disk or digital versatile disc "DVD”), a hard drive disk, tape, or any kind of interconnect (defined below).
- suitable storage medium such as a programmable electronic circuit, a semiconductor memory device, a volatile memory (e.g., random access memory, etc.), a nonvolatile memory (e.g., read-only memory, flash memory, etc.), a floppy diskette, an optical disk (e.g., compact disk or digital versatile disc "DVD”), a hard drive disk, tape, or any kind of interconnect (defined below).
- transmission path refers to either logical paths or physical paths, as defined below.
- a transmission logical path depends on the number of antennas and radios at the physical layer of the device. For example, if a MIMO system with two transmit antennas, such as Tl and T2, communicates with two receive antennas, such as Rl and R2, then there exist four transmission logical paths between the transmit antennas and the receive antennas (i.e. Tl-Rl, T1-R2, T2-R1 , T2-R2).
- a transmission logical path may be further decomposed into its constituent transmission physical paths.
- the RF energy rarely propagates only directly from a transmit antenna to a receive antenna, such as from Tl-Rl. Instead, due to reflection, refraction, diffraction, RF energy may take several routes from Tl to Rl . This is commonly referred to as multipath.
- the transmission logical path is then the combination of all propagated RF energy over all the various physical paths between Tl and Rl , as measured at Rl .
- the wireless network Ia is a multiple input multiple output (MIMO) communication system which includes a first subsystem 1 Oa in wireless communication with a second subsystem 10b.
- MIMO multiple input multiple output
- the first subsystem 10a is a transmitter subsystem
- the second subsystem 10b is a receiver subsystem.
- each or both of subsystems 10a and 10b maybe a transceiver subsystem, having transmitting and receiving capabilities.
- the first subsystem 10a includes a plurality of wireless transmitter nodes 11, such as transmitter nodes Tl and T2.
- the second subsystem 1 Ob includes at least one wireless receiver node 12, such as a receiver node Rl .
- the first subsystem 10a via wireless transmitter nodes 11, transmits the contents of a data signal 13 to the wireless receiver node 12, such as via a plurality of transmission paths 14 and 15, which corresponds to the transmitter nodes Tl and T2, respectively.
- the second subsystem 10b then collects the data received from transmission paths 14 and 15, reassembles them in the MIMO receiver 16 and outputs the reassembled the data contents in the form of signal 17, which has the same contents as that of signal 13.
- the transmission paths 14 and 15, however, may be affected by obstructions in their paths, such as inanimate obstructions such as houses, or moving obstructions such as cars, and may also be affected by interference from other wireless devices.
- a moving obstruction 18 is used throughout the detailed description.
- the movement of the obstruction 18 along a path may partially or fully block the transmission paths 14 and 15, such as at intersect points 14a and 15a respectively.
- the obstruction 18 causes one blockage at a time, so that first the transmission path 14 is blocked at intersect point 14a and then as the obstruction 18 moves along the line 19 the transmission path 14 is unblocked.
- the transmission path 15 is blocked at intersect point 15b at a future time and then later unblocked.
- FIG.2 illustrates the strength of the transmission paths 14 and 15 via lines 20 and 24 respectively.
- the strength of transmission paths 14 and 15 may be reduced by a moving obstruction 18.
- Strength of the transmission paths may be indicated by the data rate or the signal strengths between wireless nodes 11 and 12, or by other measures of the ability of the first subsystem 1 Oa to transmit data. If the obstruction 18 is moving through the wireless network 1 a along the path suggested by the line 19, the reduction in signal strength may vary over time.
- the line 20 in FIG. 2 shows the strength of the transmission path 14 as the obstruction 18 moves through the wireless network 1 a.
- the "dip" 22 represents the time when the obstruction 18 is causing the greatest reduction in strength of the transmission path 14.
- the obstruction 18 will cause a reduction in signal strength in the transmission path 15, as shown by dip 26 in line 24 representing the strength of transmission path 15.
- the dip 26 represents the time when the obstruction 18 is causing the greatest reduction in the strength of path 15.
- FIG. 3 is a flow chart, which in conjunction with FIG. 1 illustrates a method of an exemplary embodiment of the invention. As shown in FIG. 3, after the operations have begun (block 300), a first history of strength of a first transmission path, such as transmission path 14 of FIG.
- first wireless node and a second wireless node such as between Tl and Rl
- the first history may be stored in the memory 3.
- a second history of strength of a second transmission path such as transmission path 15 of FIG. 1, between a third wireless node and the second wireless node, such as between T2 and Rl, is maintained (block 320).
- the second history may be stored in the memory 3.
- the foregoing histories of the strengths of transmission paths 14 and 15 may also be maintained in a memory for a wireless node operating as a receiver, such as wireless receiver node 12.
- the histories of the strengths of transmission paths may also be maintained by a device (not shown) that receives the information on the strengths 3f transmission paths and provides predictions to the wireless nodes.
- the device may be part of the wireless receiver node 12 or a separate device.
- the histories sf the strengths of transmission paths may be between a receiver node 12 and Tansmitter nodes 11 that transmit to the wireless receiver node 12.
- a ransmission path analyzer logic 2 residing in memory 3, is used to determine the strength of the transmission paths 14 and 15 from a signal strength or a data rate ⁇ orresponding to each of the transmission paths 14 and 15.
- a spatiotemporal orrelation between the first history and the second history is performed, such as by tie spatiotemporal correlation logic 8 residing in memory 3, to determine if any hanges in the strength of the first transmission path is observed (block 330).
- This is a spatiotemporal correlation because the possible use of histories for a plurality of nodes in differing spatial relationships adds an additional functional variable to the correlation.
- the spatiotemporal correlation performed is a continuous spatiotemporal correlation.
- the spatiotemporal correlation performed is of pre-defined features in the strength of each of the transmission paths, such as transmission paths 14 and 15.
- the pre-defined features exist in at least one of a time domain or a frequency domain.
- the spatiotemporal correlation is a function of the correlation between the two signals and a time shift, delta time, between the two signals.
- FIG.4 qualitatively represents the temporal correlation 40 of the strengths 20 and 24 of two transmission paths 14 and 15 described above in conjunction with shown in FIG. 2.
- a high degree of correlation 42 between the signals such as an absolute value approaching 1, will be found for a delta time 44 approximately equal to the time difference between the times when the dips 22, 26 (FIG. 2) occurred in the strengths 20 and 24 of two transmission paths 14 and 15.
- Temporal correlations that are reasonably significant for example a correlation (the absolute value of the correlation is sufficient, the sign may in most cases be ignored) above a threshold value such as.0.4, may still have a useful predictive value.
- FIG. 5 is an exemplary flow chart, which in conjunction with FIG. 1 , llustrates another method for an embodiment of the invention which can be used in ;onjunction with the above-described embodiments of the invention.
- a data signal 13 is received in a receiver • m ⁇ t, such as the encoder 5, of the first subsystem 10a (FIG. 1) from a remote ource (not shown).
- the data signal 13 is received at a predetermined transmission ata rate.
- the data contents of the received data signal 13 are partitioned, Lich as by the processor 4, into a plurality of data signal portions, such as data ortions 13a and 13b.
- the contents of the received data signal 13 are artitioned into data portions of substantially equal size.
- a first data portion, such as data portion 13a is then transmitted via the multiplexer 6, a demodulator 7, such as mod_2, and a wireless transmitter node 11 , such as T2, to the second subsystem 10b via a first transmission path, such as transmission path 15 (block 530).
- a second data portion, such as data portion 13b is then transmitted via the demultiplexer 6, another demodulator 7, such as mod_l, and another wireless transmitter node 11, such as Tl, to the second subsystem 10b via a second transmission path, such as transmission path 14 (block 540).
- each data portion is transmitted at a rate that corresponds to the predetermined transmission data rate of the received signal 13 divided by the number of wireless transmitter nodes 11 used to transmit the data portions.
- each of the data portions 13a and 13b are transmitted at a rate of at least 30 mbps.
- the first and second data portions, such as data portions 13a and 13b, are then received in the second subsystem 10b which reassembles them via the MIMO receiver 16 and outputs the reassembled the data contents in the form of signal 17 which has the same data portions 13a and 13b as that of signal 13.
- the overall flow then ends (block 560).
- the embodiments of the invention can be used in wireless networks of greatly varying topologies having more nodes than shown in FIG. 1 , with each of the nodes possibly taking on more than one role with respect to the embodiments of the invention.
- the embodiments of the invention may be used with a variety of wireless networks, such as but not limited to 802.11 radio frequency (RF) wireless networks or infrared (IR) wireless networks.
- RF radio frequency
- IR infrared
- FIG.6 is a block diagram of a more complex wireless network Ib in which embodiments of the invention may be practiced.
- the wireless network Ib is a multiple input multiple output (MIMO) communication system which includes a first subsystem 200a in communication with a second subsystem 200b.
- the first subsystem 200a is at least a wireless transmitter •ubsystem and the second subsystem 200b is at least a wireless receiver subsystem, fhe first subsystem 200a includes a plurality of wireless transmitter nodes 211, such as Tl through TN (N>1), and the second subsystem 200b which includes a plurality of receiving wireless nodes 212, such as Rl through RM (M>1).
- MIMO multiple input multiple output
- the contents of the received signal 130 is then transmitted by the wireless transmitter nodes 211 to the wireless receiver nodes 212 such that each wireless transmitter .
- nodes 211 transmits to all of the wireless receiver nodes 212.
- transmitter node Tl transmits the same content to each of the receiver nodes Rl through RM via transmission paths 140_l through 140_M (M>1).
- the strength of transmission paths in the wireless network Ib may be reduced by a moving obstruction 18.
- changes in the strengths of transmission paths (determined by the transmission path analyzer logic 2) in the path of the obstruction 18 can be predicted (such as by the predictor logic 209 residing in memory 203) based on the spatiotemporal correlation (performed by spatiotemporal correlation logic 208) between the histories of the strengths of the transmission paths of the wireless network Ib.
- the method described above in conjunction with FIG. 5 may also be applied to the wireless network Ib wherein the signal 130 is received at a predetermined transmission rate in the encoder 205, partitioned into a plurality of Ma portions, such as 130a, 13Ob 5 130c or the like by the processor 204.
- Each of he data portions 130a, 130b, 130c or the like are then transmitted via the lemultiplexer 206 and one of the modulators 207, such as one of mod_ ⁇ through nod_N (N>1) in communication with a wireless node 211, such as a iorresponding one of Tl through TN (N>1) to each of the receiving wireless iodes 212 in the second subsystem, such as to Rl through RM (M>1).
- he data portions are transmitted at a rate that corresponds to the predetermined -ansmission data rate of the received signal 130 divided by the number of wireless transmitter nodes 11 used to transmit the data portions.
- the data portions are then received in the second subsystem 200b which reassembles them via the MIMO receiver 160 and outputs the reassembled the data contents in the form of signal 170 which has the same data portions contents and format as that of signal 130.
- Another exemplary embodiment of the invention includes a machine accessible medium, such as main memory, or other storage devices such as a hard- disk (not shown) having instructions stored thereon that, when executed by a computing device, such as by the processors 4-or 204, will cause the computing device to perform the operations described above in conjunction with FIGs. 3-6.
- a machine accessible medium such as main memory, or other storage devices such as a hard- disk (not shown) having instructions stored thereon that, when executed by a computing device, such as by the processors 4-or 204, will cause the computing device to perform the operations described above in conjunction with FIGs. 3-6.
Abstract
Description
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Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP07749818A EP1989631A4 (en) | 2006-02-24 | 2007-02-01 | Predicting future changes to strenths of paths in mimo systems |
CN2007800065521A CN101390069B (en) | 2006-02-24 | 2007-02-01 | Predicting future changes to strengths of paths in mimo systems |
CA2642118A CA2642118C (en) | 2006-02-24 | 2007-02-01 | Predicting future changes to strengths of paths in mimo systems |
JP2008556333A JP2009527986A (en) | 2006-02-24 | 2007-02-01 | Future change prediction for path strength in MIMO system |
KR1020087023187A KR101344166B1 (en) | 2006-02-24 | 2008-09-23 | Predicting future changes to strengths of paths in mimo systems |
Applications Claiming Priority (2)
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US11/361,587 US7907919B2 (en) | 2006-02-24 | 2006-02-24 | Predicting future changes to strengths of paths in MIMO systems |
US11/361,587 | 2006-02-24 |
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WO2007100442A2 true WO2007100442A2 (en) | 2007-09-07 |
WO2007100442A3 WO2007100442A3 (en) | 2007-12-13 |
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PCT/US2007/002889 WO2007100442A2 (en) | 2006-02-24 | 2007-02-01 | Predicting future changes to strenths of paths in mimo systems |
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US (1) | US7907919B2 (en) |
EP (1) | EP1989631A4 (en) |
JP (1) | JP2009527986A (en) |
KR (1) | KR101344166B1 (en) |
CN (1) | CN101390069B (en) |
CA (1) | CA2642118C (en) |
WO (1) | WO2007100442A2 (en) |
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US8045599B2 (en) * | 2005-02-17 | 2011-10-25 | Sony Corporation | Selection of training sequences for multiple-in multiple-out transmissions |
EP2530866B1 (en) * | 2009-03-27 | 2017-07-26 | Sony Corporation | Division of bit streams to produce spatial paths for multicarrier transmission |
JP5326959B2 (en) * | 2009-09-16 | 2013-10-30 | 富士通株式会社 | Communication apparatus and communication method |
WO2016190961A2 (en) * | 2015-04-03 | 2016-12-01 | President And Fellows Of Harvard College | Techniques for mitigating adverse effects of wireless link outages |
JP7200641B2 (en) * | 2018-12-07 | 2023-01-10 | 日本電信電話株式会社 | COMMUNICATION CONTROL METHOD, COMMUNICATION CONTROL DEVICE, AND COMMUNICATION CONTROL PROGRAM |
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US5465398A (en) | 1993-10-07 | 1995-11-07 | Metricom, Inc. | Automatic power level control of a packet communication link |
US5831874A (en) | 1996-05-31 | 1998-11-03 | Motorola, Inc. | Method and system for calculating a transmitted signal characteristic in an environmental model |
US5946631A (en) | 1996-10-17 | 1999-08-31 | Philips Electronics North America Corporation | Real-time CSMA method having the capability to adaptively vary cell sizes and a wireless network for implementing the same |
US6240291B1 (en) | 1999-09-09 | 2001-05-29 | The Board Of Trustees Of The Leland Stamford Junior University | Method for handoff in wireless communication systems using pattern recognition |
GB0125178D0 (en) * | 2001-10-19 | 2001-12-12 | Koninkl Philips Electronics Nv | Method of operating a wireless communication system |
GB2393618B (en) * | 2002-09-26 | 2004-12-15 | Toshiba Res Europ Ltd | Transmission signals methods and apparatus |
US6873937B2 (en) * | 2003-03-31 | 2005-03-29 | Sony Corporation | Link strength predictions based on spatiotemporal correlation of features in proximal links |
US20040259555A1 (en) * | 2003-04-23 | 2004-12-23 | Rappaport Theodore S. | System and method for predicting network performance and position location using multiple table lookups |
US6917821B2 (en) * | 2003-09-23 | 2005-07-12 | Qualcomm, Incorporated | Successive interference cancellation receiver processing with selection diversity |
US7231559B2 (en) | 2003-12-17 | 2007-06-12 | Sony Corporation | Outage predictor for communication link |
KR100912226B1 (en) * | 2008-06-27 | 2009-08-14 | 삼성전자주식회사 | Codebook design method for multiple input multiple output system and method for using the codebook |
-
2006
- 2006-02-24 US US11/361,587 patent/US7907919B2/en active Active
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2007
- 2007-02-01 CA CA2642118A patent/CA2642118C/en not_active Expired - Fee Related
- 2007-02-01 JP JP2008556333A patent/JP2009527986A/en active Pending
- 2007-02-01 WO PCT/US2007/002889 patent/WO2007100442A2/en active Application Filing
- 2007-02-01 CN CN2007800065521A patent/CN101390069B/en not_active Expired - Fee Related
- 2007-02-01 EP EP07749818A patent/EP1989631A4/en not_active Withdrawn
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2008
- 2008-09-23 KR KR1020087023187A patent/KR101344166B1/en active IP Right Grant
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Publication number | Publication date |
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CA2642118C (en) | 2015-03-24 |
EP1989631A2 (en) | 2008-11-12 |
CN101390069B (en) | 2012-05-30 |
US7907919B2 (en) | 2011-03-15 |
CN101390069A (en) | 2009-03-18 |
WO2007100442A3 (en) | 2007-12-13 |
CA2642118A1 (en) | 2007-09-07 |
US20070202817A1 (en) | 2007-08-30 |
EP1989631A4 (en) | 2010-01-06 |
JP2009527986A (en) | 2009-07-30 |
KR101344166B1 (en) | 2013-12-20 |
KR20080098542A (en) | 2008-11-10 |
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