System and method for multi-access MIMO channels with feedback capacity constraint
AssigneeThe University of Hong Kong
InventorKin Nang Lau
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Abstract
Systems and methods of MIMO wireless communication system with partial feedback are disclosed. In one embodiment, a base station estimates the channel matrices of the K mobile units and transmits an index value corresponding to each of the estimated channel matrix. Each mobile unit selects a power control matrix and beam-forming matrix based on the received index value and transmits its data stream to the base station using the selected power control and beam-forming matrix. A method for generating the sets of power control matrices, beam-forming matrices, and partitions of the channel matrix space is disclosed.
Claims19
A multiple-input, multiple-output (MIMO) system comprising:
- at least one mobile unit configured to transmit a signal based on a selected power matrix and a selected beam-forming matrix;
- and
- a base station configured to receive the signal from the at least one mobile unit, the base station comprising:
- a channel state information—receiver (CSIR) estimator configured to receive the signal and estimate a channel matrix for the at least one mobile device;
- and
- a channel state information—transmitter (CSIT) generator configured to broadcast an index to the at least one mobile unit, the index corresponding to a region of a channel matrix space enclosing the estimated channel matrix of the at least one mobile unit;
- wherein the selected power matrix and the selected beam-forming matrix are selected based on the index broadcast by the CSIT generator.
A method of optimizing the capacity of a MIMO system, the MIMO system characterized by K mobile units, each mobile unit characterized by Q levels, the K mobile units transmitting to a base station having nT antennas configured to receive a signal transmitted by the K mobile units, the method comprising:
- i. generating at least one positive, semidefinite channel matrices of size nR×nT;
- j. initializing at least one power control matrix and at least one beam-forming matrix;
- k. partitioning a K×nR×nT channel matrix space into a set of partition regions;
- l. generating at least one power control matrix and at least one beam-forming matrix based on the at least one channel matrix, the at least one power control matrix, the at least one beam-forming matrix, and the set of partition regions;
- m. repeating steps c and d a preselected number, Ng, of times;
- n. estimating a capacity of the at least one generated power control matrix, the at least one generated beam-forming matrix, and the set of partition regions;
- o. repeating steps a through f a preselected number, Ns, of times;
- and
- p. selecting the at least one generated power control matrix, the at least one generated beam-forming matrix, and the set of partition regions corresponding to the largest capacity.
A MIMO wireless base station comprising:
- at least one antenna configured to receive a signal from at least one mobile unit;
- a receiver configured to receive the signal from the at least one antenna;
- a CSIR estimator configured to estimate a channel matrix for the at least one mobile unit based in part on the signal from the at least one antenna;
- and
- a CSIT generator configured to broadcast to the at least one mobile unit a partition index corresponding to a partition containing the channel matrix of the at least one mobile unit.
A MIMO wireless mobile unit comprising:
- at least one antenna configured to transmit a signal to a base station;
- a transmitter configured to transmit a signal containing an encoded data stream over the at least one antenna;
- an index decoder configured to receive a partial feedback signal and extract an index associated with the mobile unit from the partial feedback signal;
- and
- a power and beam-forming control configured to retrieve a power control matrix and beam-forming matrix from a set of pre-stored power control and beam-forming matrices based on the extracted index;
- wherein the transmitter generates the transmitted signal by modifying the encoded data stream with the retrieved power control matrix and beam-forming matrix.
A method for optimizing the capacity of a MIMO wireless system with partial feedback, the system characterized by K mobile units having Q levels, each mobile unit characterized by a channel matrix, the channel matrix embedded in a K×nR×nT dimension channel matrix space, the method comprising:
- (a) partitioning the matrix space into QK regions, {Rq};
- (b) determining an optimal set of QK power control matrices, {ρq}, and an optimal set of QK bream-forming matrices, {Bq} based on {Rq};
- (c) estimating a capacity of the MIMO system based on {Rq}, {ρq}, and {Bq};
- repeating steps (a) through (c) a predetermined number of times;
- and
- selecting a set of {Rq}, {ρq}, and {Bq} having the largest estimated capacity.
Dependencies are inferred from the claim text.