Multi-antenna transmission for spatial division multiple access
An uplink channel response matrix is obtained for each terminal and decomposed to obtain a steering vector used by the terminal to transmit on the uplink. An “effective” uplink channel response vector is formed for each terminal based on its steering vector and its channel response matrix. Multiple sets of terminals are evaluated based on their effective channel response vectors to determine the best set (e.g., with highest overall throughput) for uplink transmission. Each selected terminal performs spatial processing on its data symbol stream with its steering vector and transmits its spatially processed data symbol stream to an access point. The multiple selected terminals simultaneously transmit their data symbol streams via their respective MIMO channels to the access point. The access point performs receiver spatial processing on its received symbol streams in accordance with a receiver spatial processing technique to recover the data symbol streams transmitted by the selected terminals.
1. A method of receiving data in a multiple-input multiple-output (MIMO) communication system, comprising:
obtaining, from a plurality of receive antennas at a receiving entity, a plurality of received symbol streams for a plurality of data symbol streams sent by a plurality of transmitting entities, one data symbol stream for each transmitting entity, wherein the data symbol stream for each transmitting entity is spatially processed with a steering vector for the transmitting entity and sent from a plurality of transmit antennas at the transmitting entity; and
processing the plurality of received symbol streams in accordance with a receiver spatial processing technique to obtain a plurality of recovered data symbol streams, which are estimates of the plurality of data symbol streams,
wherein the steering vector for each transmitting entity is derived by:
decomposing a channel response matrix for the transmitting entity to obtain a plurality of eigenvectors and a plurality of singular values, and
forming the steering vector for the transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values.
2. The method of claim 1 , wherein the receiver spatial processing technique is a channel correlation matrix inversion (CCMI) technique or a minimum mean square error (MMSE) technique.
3. The method of claim 1 , wherein the receiver spatial processing technique is a successive interference cancellation (SIC) technique.
4. The method of claim 1 , wherein the steering vector for each transmitting entity is equal to the eigenvector corresponding to the largest singular value.
5. The method of claim 1 , wherein the steering vector for each transmitting entity contains a plurality of elements having same magnitude and phases equal to phases of a plurality of elements of the eigenvector corresponding to the largest singular value.
6. A method of receiving data in a multiple-input multiple-output (MIMO) communication system, comprising:
obtaining, from a plurality of receive antennas at a receiving entity, a plurality of received symbol streams for a plurality of data symbol streams sent by a plurality of transmitting entities, one data symbol stream for each transmitting entity, wherein the data symbol stream for each transmitting entity is spatially processed with a steering vector for the transmitting entity and sent from a plurality of transmit antennas at the transmitting entity;
processing the plurality of received symbol streams in accordance with a receiver spatial processing technique to obtain a plurality of recovered data symbol streams, which are estimates of the plurality of data symbol streams;
evaluating each of a plurality of sets of transmitting entities for possible transmission based on a metric and steering vectors for the transmitting entities in the set; and
selecting a set of transmitting entities with a highest metric value for transmission.
7. An apparatus at a receiving entity in a multiple-input multiple-output (MIMO) communication system, comprising:
a plurality of receiver units operative to obtain from a plurality of receive antennas a plurality of received symbol streams for a plurality of data symbol streams sent by a plurality of transmitting entities, one data symbol stream for each transmitting entity, wherein the data symbol stream for each transmitting entity is spatially processed with a steering vector for the transmitting entity and sent from a plurality of transmit antennas at the transmitting entity; and
a receive spatial processor operative to process the plurality of received symbol streams in accordance with a receiver spatial processing technique to obtain a plurality of recovered data symbol streams, which are estimates of the plurality of data symbol streams,
wherein the steering vector for each transmitting entity is derived by:
decomposing a channel response matrix for the transmitting entity to obtain a plurality of eigenvectors and a plurality of singular values, and
forming the steering vector for the transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values.
8. The apparatus of claim 7 , wherein the receiver spatial processing technique is a channel correlation matrix inversion (CCMI) technique or a minimum mean square error (MMSE) technique.
9. An apparatus at a receiving entity in a multiple-input multiple-output (MIMO) communication system, comprising:
means for obtaining from a plurality of receive antennas a plurality of received symbol streams for a plurality of data symbol streams sent by a plurality of transmitting entities, one data symbol stream for each transmitting entity, wherein the data symbol stream for each transmitting entity is spatially processed with a steering vector for the transmitting entity and sent from a plurality of transmit antennas at the transmitting entity; and
means for processing the plurality of received symbol streams in accordance with a receiver spatial processing technique to obtain a plurality of recovered data symbol streams, which are estimates of the plurality of data symbol streams,
wherein the steering vector for each transmitting entity is derived by:
decomposing a channel response matrix for the transmitting entity to obtain a plurality of eigenvectors and a plurality of singular values, and
forming the steering vector for the transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values.
10. The apparatus of claim 9 , wherein the receiver spatial processing technique is a channel correlation matrix inversion (CCMI) technique or a minimum mean square error (MMSE) technique.
11. A method of deriving steering vector for data transmission in a multiple-input multiple-output (MIMO) communication system, comprising:
obtaining a channel response matrix indicative of a response of a MIMO channel between a transmitting entity and a receiving entity in the MIMO system;
decomposing the channel response matrix to obtain a plurality of eigenvectors and a plurality of singular values, one eigenvector for each singular value; and
deriving the steering vector for the transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values, and
wherein a plurality of steering vectors are derived for a plurality of transmitting entities and used for spatial processing by the plurality of transmitting entities to concurrently transmit a plurality of data symbol streams to the receiving entity.
12. The method of claim 11 , wherein the steering vector for each transmitting entity is the eigenvector corresponding to the largest singular value.
13. The method of claim 11 , wherein the steering vector for each transmitting entity contains a plurality of elements having same magnitude and phases equal to phases of a plurality of elements of the eigenvector corresponding to the largest singular value.
14. An apparatus in a multiple-input multiple-output (MIMO) communication system, comprising:
a channel estimator operative to obtain a channel response matrix indicative of a response of a MIMO channel between a transmitting entity and a receiving entity in the MIMO system; and
a controller operative to decompose the channel response matrix to obtain a plurality of eigenvectors and a plurality of singular values, one eigenvector for each singular value and to derive the steering vector for the transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values, and
wherein a plurality of steering vectors are derived for a plurality of transmitting entities and used for spatial processing by the plurality of transmitting entities to concurrently transmit a plurality of data symbol streams to the receiving entity.
15. An apparatus in a multiple-input multiple-output (MIMO) communication system, comprising:
means for obtaining a channel response matrix indicative of a response of a MIMO channel between a transmitting entity and a receiving entity in the MIMO system;
means for decomposing the channel response matrix to obtain a plurality of eigenvectors and a plurality of singular values, one eigenvector for each singular value; and
means for deriving the steering vector for the transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values, and
wherein a plurality of steering vectors are derived for a plurality of transmitting entities and used for spatial processing by the plurality of transmitting entities to concurrently transmit a plurality of data symbol streams to the receiving entity.