Rank adaptive transmission methods and apparatuses
Spatial multiplexing and transmit diversity can improve the capacity of a wireless communication system. The system and method adapts communication schemes for communication systems with multiple antennas utilizing at least two transmission modes. The at least two transmission modes can, but are not necessarily, used for uplink communications. The two transmission modes may be chosen from the group consisting of a single antenna mode, a diversity mode a spatial multiplexed mode and a mixed diversity and spatial multiplexed mode. The at least two transmission modes may involve adaptation among multiple transmitters. At least one receiver may indicate a transmission mode to be used by a transmitter for a subsequent transmission. A transmitter may determine a transmission mode to be used for a subsequent transmission. The transmission mode can be based on channel sounding.
1. A method of transmitting a data signal from a plurality of transmit antennas on at least one user equipment (UE) device to at least a receive antenna on a base station (BS) in a wireless communication network, comprising:
adapting a rank of transmission and a degree of transmit diversity based on one or more network parameters including a traffic type and a number of antennas available at the UE for uplink transmission, wherein the number of antennas available changes from all of the plurality of transmit antennas to less than all of the plurality of transmit antennas;
splitting the data signal into a set of independent data streams, wherein the rank of transmission is represented by a number of independent data streams in the set between the at least one UE and the BS;
encoding each of the data steams from a subset of the set of independent data streams using space-time encoder logic to provide space-time encoded sequences, based on a mapping control signal; and
transmitting the space-time encoded sequences and any non space-time encoded data streams from the set of independent data streams using the plurality of transmit antennas.
2. The method of claim 1 wherein the network parameters comprise an Effective Channel Quality Indicator (CQI).
3. The method of claim 1 wherein the network parameters comprise an available transmit power.
4. The method of claim 1 wherein the network parameters comprise a total uplink (UL) traffic load.
5. The method of claim 1 wherein the rank of transmission is less than or equal to a maximum supported rank.
6. The method of claim 1 wherein the rank of transmission is based on an Effective CQI of a virtual channel matrix.
7. The method of claim 1 wherein the plurality of transmit antennas are on the same user equipment (UE) device.
8. The method of claim 1 wherein the plurality of transmit antennas are on different user equipment (UE) devices, wherein the different UE devices cooperate during transmission.
9. The method of claim 1 wherein the adapting the rank of transmission and the degree of transmit diversity is controlled by a scheduler.
10. The method of claim 9 wherein the adapting the rank of transmission and the degree of diversity is controlled by the scheduler on a periodic basis.
11. The method of claim 1 wherein the base station (BS) selects the plurality of transmit antennas to be used for uplink transmission.
12. An apparatus comprising:
a plurality of transmit antennas; and
transmission circuitry operable to:
adapt a rank of transmission and a degree of transmit diversity based on one or more network parameters including a traffic type and a number of antennas available for uplink transmission, wherein the number of antennas available changes from all of the plurality of transmit antennas to less than all of the plurality of transmit antennas;
split a data signal into a set of independent data streams between the plurality of transmit antennas and at least one receiver antenna on a base station, wherein the rank of transmission is represented by a number of independent data streams in the set;
encode each of the data steams from a subset of the set of independent data streams using space-time encoder logic to provide space-time encoded sequences, based on a mapping control signal; and
transmit the space-time encoded sequences and any non space-time encoded data streams from the set of independent data streams using the plurality of transmit antennas.
13. The apparatus of claim 12 wherein the plurality of transmit antennas are on the same user equipment (UE) device.
14. The apparatus of claim 13 wherein the transmit circuitry is further operable to adapt at least one of the rank of transmission and the degree of transmit diversity by applying a pre-coding operation.
15. The apparatus of claim 12 wherein the plurality of transmit antennas are on different user equipment (UE) devices, wherein the different UE devices cooperate during transmission.