WO2009023532A2 - Channel aware multiple user mimo scheme unified with single user closed loop mimo - Google Patents
Channel aware multiple user mimo scheme unified with single user closed loop mimo Download PDFInfo
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- WO2009023532A2 WO2009023532A2 PCT/US2008/072511 US2008072511W WO2009023532A2 WO 2009023532 A2 WO2009023532 A2 WO 2009023532A2 US 2008072511 W US2008072511 W US 2008072511W WO 2009023532 A2 WO2009023532 A2 WO 2009023532A2
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- channel quality
- quality indicator
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- indicator values
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- 239000013598 vector Substances 0.000 claims abstract description 51
- 239000011159 matrix material Substances 0.000 claims abstract description 20
- 230000005540 biological transmission Effects 0.000 claims description 54
- 238000000034 method Methods 0.000 claims description 24
- 238000000354 decomposition reaction Methods 0.000 claims description 6
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 2
- 238000010586 diagram Methods 0.000 description 10
- 230000006978 adaptation Effects 0.000 description 8
- 238000001514 detection method Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 1
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Classifications
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- 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
- H04B7/0452—Multi-user MIMO systems
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- 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
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
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- 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
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0621—Feedback content
- H04B7/063—Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
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- 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
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0621—Feedback content
- H04B7/0632—Channel quality parameters, e.g. channel quality indicator [CQI]
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- 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
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0621—Feedback content
- H04B7/0634—Antenna weights or vector/matrix coefficients
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- 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
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0636—Feedback format
- H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
Definitions
- MU-MIMO multiple user - multiple-input, multiple-output
- SU-MIMO single user-MIMO
- An asymmetric configuration may occur when a base station (BS) has a greater number of transmit (Tx) antennas than the number of receive (Rx) antennas at the subscriber station (SS), or in a high correlation channel condition.
- BS base station
- Tx transmit
- Rx receive
- SS subscriber station
- MU-MIMO differs from SU-MIMO in that MU-MIMO may involve the transmission of transmission streams for multiple users in one transmission function unit.
- FIG. 1 is a block diagram of a MU-MIMO system in accordance with one or more embodiments
- FIG. 2 is a diagram of a channel aware MU-MIMO transmission scheme with multiple streams in accordance with one or more embodiments
- FIG. 3 is a diagram of a MU-MIMO transmission scheme using feedback of a channel quality indicator and vector (CQI/V) with no downsampling in accordance with one or more embodiments;
- FIG. 4 is a diagram of a MU-MIMO transmission scheme using feedback of a channel quality indicator and vector (CQI/V) with downsampling in accordance with one or more embodiments.
- FIG. 5 is a flow diagram of a method for unifying a multi-user MIMO scheme with a single-user MIMO scheme in accordance with one or more embodiments.
- Coupled may mean that two or more elements are in direct physical and/or electrical contact.
- coupled may also mean that two or more elements may not be in direct contact with each other, but yet may still cooperate and/or interact with each other.
- “coupled” may mean that two or more elements do not contact each other but are indirectly joined together via another element or intermediate elements.
- “On,” “overlying,” and “over” may be used to indicate that two or more elements are in direct physical contact with each other. However, “over” may also mean that two or more elements are not in direct contact with each other. For example, “over” may mean that one element is above another element but not contact each other and may have another element or elements in between the two elements.
- the term “and/or” may mean “and”, it may mean “or”, it may mean “exclusive-or”, it may mean “one”, it may mean “some, but not all”, it may mean “neither", and/or it may mean “both”, although the scope of claimed subject matter is not limited in this respect.
- the terms “comprise” and “include,” along with their derivatives, may be used and are intended as synonyms for each other.
- MIMO system 100 may comprise a base station (BS) 110 and one or more subscriber stations (SS) 114, including a first subscriber station (SSi), a second subscriber station (SS 2 ), up to N number of subscriber stations (SS N ) in which one or more of the subscriber stations 114 may wirelessly communicate with base station 110.
- base station 110 may comprise multiple antennas 112, and the respective subscriber stations 114 may likewise have one or more antennas 116, 118, and/or 120.
- the number one or more of subscriber stations 114 may have its own number of antennas, where for example the number of antennas 116 of first subscriber station SSi may be different than the number of antennas 118 of second subscriber station SS 2 , which both may be different than the number of antennas of an Nth subscriber station SS N - Likewise, one or more of the subscriber stations 114 may have a different number of antennas than the number of antennas 112 of base station, although in some instances one or more of base station 110 and any one or more of subscriber stations 114 may have the same number of antennas, and the scope of the claimed subject matter is not limited in this respect. It should also be noted that the base station 110 and subscriber station 114 model shown in FIG.
- base station 110 may itself be a subscriber station 114, and/or one or more of the subscriber stations 114 may communicate directly with another one or more of the subscriber stations 114, for example in an ad hoc network arrangement or the like, and the scope of the claimed subject matter is not limited in this respect.
- communication between base station 110 an one or more of subscriber stations 114 may involve precoding, spatial multiplexing, and/or diversity encoding, alone or in combination.
- base station 110 may communicate directly with one of the subscriber stations 114 by directing all of its antenna resources to the respective subscriber station 114, for example to achieve higher data rates, or alternatively base station 110 may divide some of its antennal resources between or more subscriber stations 114 for example to optimize serving a greater number of subscriber stations 114.
- MIMO system 100 may implement a channel aware multi-user MIMO (CA-MU-MIMO) system.
- CA-MU-MIMO channel aware multi-user MIMO
- a precoding vector and/or the codebook index may be channel aware based at least in part on feedback received from one or more user such as one or more of subscriber stations 114.
- channel quality indicators CQIs
- the user scheduling in base station 110 may be based on based on one or more principles, for example user orthogonality, or the maximization of proportional fairness metric, and so on.
- two kinds of CQIs may be used, for example Rank-1 and Rank-2, for MIMO rank/mode adaptation.
- Interference unaware Rank-1 CQIs may be used for the selection of the precoding vector, and interference aware Rank-2 CQIs may be used for MIMO rank/link/mode adaptation and user selection.
- the channel aware MU-MIMO scheme implemented by MIMO system 100 may be unified with a single user closed- loop MIMO scheme. Such a MU-MIMO scheme id discussed in greater detail with respect to FIG. 2, FIG. 3, and FIG. 4, below.
- a transmission procedure capable of being implemented by base station 110 may be as follows for multiple streams such as a 2x2 arrangement with two streams. It should be noted that the nomenclature 2x2 refers to base station 110 using two antennas for transmission to a subscriber station 114 using two antennas for receiving. Briefly, the transmission procedure may involve a channel aware MU-MIMO procedure with CQI and vector feedback.
- Subscriber station 114 may perform singular value decomposition (SVD) of all the user channels in second to last sub frame 214 of ith frame 212 to get the beam forming vectors for each subscriber station 114. Then the subscriber stations 114 feed back a Rank-1 CQI to base station 110. Also each of the subscriber stations 114 will feed back its respective two main vectors to base station 110. Base station 110 then determines the selected beam forming vectors, which in the 2x2 case comprises two vectors, from the subscriber station 114 having the best Rank-1 CQI value. Base station 110 may then broadcast in the last sub frame 216 of the ith frame 210 the selected vectors from the subscriber station 114 having the best Rank-1 CQI value to all subscriber stations 114.
- SSD singular value decomposition
- each subscriber station calculates the Rank-2 CQIs, which in the present case may comprise two Rank-2 CQIs, by using the broadcasted vectors received from base station 110. Subscriber stations 114 may then feed back calculated two CQIs to base station 110. Upon receipt thereof, base station 110 may determine the pairing users based on scheduling criteria and/or MIMO mode/rank according to the Rank-1 /Rank-2 CQIs base station 100 received from subscriber stations 114. In the event that Rank-1 mode or the same user is allocated to two streams over the same resource block (RB), then base station 110 may elect to use single-user MIMO transmission. Otherwise, multi-user transmission is selected.
- RB resource block
- a more detailed transmission procedure for the channel aware MU-MIMO scheme 200 of FIG. 2 may be as follows.
- each subscriber station 114 feeds back one Rank-1 CQI value to base station 110 for the rank adaptation based on the channel information for itself, on which the SVD decomposition may be based.
- the Rank-1 CQI calculation there is no interference existing from the second stream.
- Each subscriber station then feeds back its two main vectors, or beam forming matrix, from its respective SVD decomposition over its own channel matrix to base station 110.
- base station 110 compares all of the Rank-1 CQIs received from each of the subscriber stations 114 and determines which of the subscriber stations 114 has the best Rank-1 CQI value. Base station 110 then may determine a selected beam forming matrix comprising two main beam forming vectors from the subscriber station 114 having the best Rank-1 CQI value. Base station 110 then broadcasts the selected beam forming matrix to all of the subscriber stations 114 in MIMO system 100.
- each of the subscriber stations calculates the Rank-2 CQIs, which may comprise two Rank-2 CQIs in the two stream case, by using the beam forming matrix vectors, in this case two vectors, and then feeds back the two calculated CQIs to base station 110.
- the Rank-2 CQIs may be calculated with an interference aware minimum mean squared error (MMSE) receiver at the subscriber stations 114. Each subscriber station 114 then feeds back two Rank-2 CQIs values to base station 10 for user pairing.
- MMSE interference aware minimum mean squared error
- base station 110 may determine the pairing subscriber stations 114 based on scheduling criteria for MU-MIMO and/or based on MIMO mode/rank according to the Rank-l/Rank-2 CQIs received previously from subscriber stations 114. Base station 110 may then start to transmit data by using the precoding vectors follows. If the value of the Rank-1 CQI is greater than the single-user Rank-2 CQIs and/or the multi-user Rank-2 CQIs, base station 110 selects the SU-MIMO Rank-1 mode for data transmission.
- base station 110 will transmit one stream with the first vector from broadcasted beam forming matrix for the selected subscriber station 114.
- This selected subscriber station 114 corresponds to the highest valued Rank-1 CQI compared with the SU-MIMO Rank-2 CQIs and/or MU-MIMO Rank-2 CQIs.
- base station 110 selects the SU-MIMO Rank-2 mode for data transmission. In this case, base station 110 will transmit two streams with the two vectors from the broadcasted beam forming matrix for the selected subscriber station 114. This selected subscriber station 114 corresponds to the highest valued SU Rank- 2 CQIs compared with the SU Rank-1 CQI and/or MU Rank-2 CQIs.
- base station 110 selects the MU-MIMO Rank-2 mode for data transmission. In this case, base station 110 will transmit two streams with the two beam forming vectors from the broadcasted beam forming matrix for the selected two different subscriber stations. These two selected subscriber stations 114 will have the highest valued MU Rank-2 CQIs, based on a summation over two different subscriber stations 114, compared with the SU Rank-1 CQI and/or the SU Rank-2 CQIs.
- the channel aware MU-MIMO scheme 200 shown in FIG. 2 may be extended to a higher number of streams, more than two streams, and a higher number of antenna configurations, for example a 4x2 antenna configuration where base station 110 may have four antennas and subscriber stations 114 may have two antennas, or a 4x4 antenna configuration where base station 110 may have four antennas and subscriber stations 114 may have four antennas, and so on.
- the difference may comprise the number of feedback beam forming vectors and CQIs used. Under the higher stream number/higher antenna configuration, there will be corresponding feedback number for the beam forming vectors and CQIs.
- FIG. 3 a diagram of a MU-MIMO transmission scheme using feedback of a channel quality indicator and vector (CQI/V) with no downsampling in accordance with one or more embodiments will be discussed.
- CQI/V channel quality indicator and vector
- the frame size is 5 milliseconds, although the scope of the claimed subject matter is not limited in this respect.
- every subscriber stationl 14 may feed back the same contents to base station 110, for example, each subscriber station 114 will feedback one CQI value based at least in part on the latest channel information.
- Each subscriber station 114 will calculate the two Rank-2 CQIs based at least in part on the broadcasted two or more beam forming vectors received from base station 110, and then feedback the Rank-2 CQIs back to base station 110.
- base station 110 will select two new beam forming vectors from the subscriber stations 114 having the highest valued Rank-1 CQI for broadcasting.
- Base station 110 will transmit the data by the selected MIMO mode, either a SU-MIMO mode or a MU-MIMO mode, and use the selected beam forming vector for precoding over the data.
- the feedback over the whole band within one subframe may be based at least in part on a Best-M algorithm to reduce the feedback overhead.
- the beam forming vector may also be utilized jointly with CQI feedback based at least in part on a Best-M algorithm. Such an embodiment may be implemented via a streamline mode.
- Each subframe may have the same feedback overhead, and each subframe may implement switching between an SU-MIMO mode and an MU-MIMO mode, between Rank- 1 and Rank-2, and so on, although the scope of the claimed subject matter is not limited in these respects.
- FIG. 4 a diagram of a MU-MIMO transmission scheme using feedback of a channel quality indicator and vector (CQI/V) with downsampling in accordance with one or more embodiments will be discussed.
- downsampling may be used for feedback in the frame level.
- the frame size may be 5 milliseconds or higher.
- MU-MIMO scheme 400 of FIG. 4 is substantially similar to MU-MIMO scheme 300 of FIG. 3, where the difference may comprise the switching unit or switching period. Each frame of 5 ms or longer frames greater than 5 ms will feedback the same contents.
- each subscriber station 114 will feedback one CQI based at least in part on the latest channel information.
- Each subscriber station 114 will calculate two Rank-2 CQIs based at least in part on the broadcasted two beam forming vectors which will then be feedback to base station 110.
- base station 110 will select two new beam forming vectors from the subscriber station having the highest value Rank-1 CQI for broadcasting.
- Base station 110 will transmit the data via the selected MIMO mode, either SU-MIMO or MU-MIMO, and use the selected beam forming vector for precoding over the data.
- the feedback over the whole band within one frame of 5 ms or longer frames greater than 5 ms may be based at least in part on a Best-M algorithm to reduce the feedback overhead.
- the beam forming vector also may be used jointly with CQI feedback based at least in part on a Best-M algorithm. Such a case may be implemented via stream-line mode.
- Each frame of 5 ms or longer frames greater than 5 ms will have the same feedback overhead, and each frame of 5 ms or longer frames greater than 5 ms may have the switching between SU-MIMO and MU-MIMO; between Rank-1 and Rank-2, and so on, although the scope of the claimed subject matter is not limited in these respects.
- a channel aware MU-MIMO scheme may implement scheduling and/or hybrid automatic repeat request (HARQ) retransmission.
- HARQ hybrid automatic repeat request
- user scheduling user scheduling in base station may be based at least in part on principles such as user orthogonality or the maximization of proportional fairness metric, and so on.
- base station 110 will calculate the PF metric based at least in part on the SU Rank-1, SU Rank-2 and/or MU Rank-2 CQIs, and/or based at least in part on criteria to select out one MIMO mode for transmission. User pairing may then be determined.
- HARQ retransmission could be implemented as an asynchronous mode or a synchronous mode.
- a non-blanking/blanking HARQ mode may be utilized for a channel aware MU-MIMO scheme in which MU-MIMO will have two streams for transmission even if MIMO system 100 is undergoing retransmission.
- MU-MIMO will have two streams for transmission even if MIMO system 100 is undergoing retransmission.
- the precoding vector used for new data and retransmission may be the latest beam forming vectors from the MU-MIMO scheduling.
- mode/rank adaptation may be utilized to keep the link performance even if the channel is changing.
- the changing mode could be implemented for both flexible and/or semi-static solutions.
- For the flexible adaptation mode subscriber stations will feed back CQI values of all adaptable ranks/modes, and then base station 110 will collect all the information for mode/rank determination.
- the changing could be implemented at a frame by frame level. Such a changing mechanism may have the sufficient performance with higher feedback overhead.
- semi-static adaptation subscriber stations 114 will request adaptation when a subscriber station 114 notices a channel change, and then base station 110 decides the needed adaptation. In such an arrangement, the frequency may change relatively slowly however using a lesser amount of feedback overhead.
- the channel aware MU-MIMO scheme may utilize the downlink transmission for pilot signal measurement and/or detection. Pilots for measurement may be implemented, for example from a scattered common pilot, a midamble, reference signals to calculate out the MIMO CQI feedback, such as channel quality indicator (CQI), control sequence indicator (CSI), power margin indicator (PMI), codebook index, and so on. Where pilots are used for demodulation, a channel aware MU-MIMO scheme may utilize a dedicated, precoded pilot for the data detection to save the pilot overhead, although the scope of the claimed subject matter is limited in these respects.
- pilots for measurement may be implemented, for example from a scattered common pilot, a midamble, reference signals to calculate out the MIMO CQI feedback, such as channel quality indicator (CQI), control sequence indicator (CSI), power margin indicator (PMI), codebook index, and so on.
- CQI channel quality indicator
- CSI control sequence indicator
- PMI power margin indicator
- codebook index codebook index
- Method 500 of FIG. 5 comprises one particular order of an SU-MIMO and MU-MIMO scheme, however the method 500 may comprise other orders, and/or greater or fewer blocks, than shown in FIG. 5, and the scope of the claimed subject matter is not limited in this respect.
- base station 110 receives Rank-1 CQI values from one or more subscriber stations 114, which may be referred to generally as users.
- base station 110 receives two or more vectors from the respective subscriber stations corresponding to a beam forming matrix codebook.
- Base station 110 determines at block 514 which of the users as the best Rank-1 CQI value. Base station 110 then selects the vectors corresponding to the user having the best Rank-1 CQI value at block 516. Using the vectors from the user having the best Rank-1 CQI value, base station 110 broadcasts the vectors to all the users at block 518. The users will then calculate Rank-2 CQI values by using the broadcasted vectors and then feeds back the Rank-2 CQI values which are received by base station 110 at block 520. Base station 110 then determines user pairing based at least in part on the Rank-2 CQI values at block 522 by comparing the Rank-1 and Rank-2 values received from the subscriber stations 114.
- base station 110 determines at block 524 if a Rank-1 CQI value is the best of the CQI values, or if the same user is allocated to two or more streams, then base station 110 selects single-user MIMO operation. Otherwise, if base station determines at block 526 two or more users in combination have the best Rank-2 CQI values, base station 110 selects multi-user MIMO operation.
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Abstract
Description
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CN200880102523.XA CN101785210B (en) | 2007-08-10 | 2008-08-07 | Channel aware multiple user MIMO scheme unified with single user closed loop MIMO |
GB1002392.7A GB2465111B (en) | 2007-08-10 | 2008-08-07 | Channel aware multiple user mimo scheme unified with single user closed loop mimo |
DE112008002055.8T DE112008002055B4 (en) | 2007-08-10 | 2008-08-07 | Channel-aware multi-user MIMO scheme unified with single-user closed-loop MIMO |
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US12/183,371 US7716909B2 (en) | 2008-07-31 | 2008-07-31 | Apparatus and method for picking up berries |
US12/183,371 | 2008-07-31 |
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WO2013143099A1 (en) * | 2012-03-29 | 2013-10-03 | Nec(China) Co., Ltd. | Method and apparatus for link adaptation in precoded mimo systems |
CN103812603A (en) * | 2012-11-12 | 2014-05-21 | 华为技术有限公司 | SUMIMO/MUMIMO dynamic switching feedback method and device |
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Also Published As
Publication number | Publication date |
---|---|
CN101785210A (en) | 2010-07-21 |
CN101785210B (en) | 2013-04-24 |
DE112008002055B4 (en) | 2015-12-17 |
GB2465111B (en) | 2012-06-06 |
WO2009023532A3 (en) | 2009-04-16 |
GB2465111A (en) | 2010-05-12 |
DE112008002055T5 (en) | 2010-09-16 |
GB201002392D0 (en) | 2010-03-31 |
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