FIELD OF INVENTION

The present invention is related to wireless communication systems. More particularly, the present invention is related to a method and apparatus for implementing spatial processing with unequal modulation and coding schemes (MCSs).

BACKGROUND

The IEEE 802.1 in joint proposal group currently proposes using a hybrid space-time block code (STBC) and spatial division multiplexing (SDM) scheme for the next generation of high performance wireless networks. This hybrid STBC/SDM scheme results in unbalanced quality of service for data streams which translates into lower residual signal-to-noise ratio (SNR) at the output of a receiver. In conventional systems, equal MCSs are applied to all spatial streams. However, this results in a loss of benefits of the diversity gain for the spatial stream carried by STBC precoding.

Therefore, it would be desirable to provide a method and apparatus for applying unequal MCSs or stream-dependent MCSs while performing spatial processing, such as STBC.

SUMMARY

The present invention is related to a method and apparatus for implementing spatial processing with unequal MCSs or stream-dependent MCSs. Input data may be parsed into a plurality of data streams, and spatial processing is performed on the data streams to generate a plurality of spatial streams. An MCS for each data stream is selected independently. The spatial streams are then transmitted via multiple transmit antennas. At least one of the techniques of STBC, space frequency block coding (SFBC), quasi-orthogonal Alamouti coding, time reversed space time block coding, linear spatial processing and cyclic delay diversity (CDD) may be performed on the data/spatial streams. An antenna mapping matrix may then be applied to the spatial streams. The resulted spatial streams are then transmitted via multiple transmit antennas. The MCS for each data stream may be determined based on an SNR of each spatial stream associated with the data stream.

