Research On A New Antenna Selection Algorithm In STBC And VBLAST Hybrid Coding Systems

Multiple-input multiple-output (MIMO) technology can not only significantly increase the spectrum efficiency of wireless communication systems but also improve the system bit error rate (BER) performance, is widely considered one of the key technologies for next-generation mobile communication. Traditional MIMO technology includes space-diversity technique and space-multiplexing technique. The key of space-diversity technique is the space-time coding technique. The existing space-time coding technique includes the space-time block coding (STBC) and the space-time trellis coding (STTC). The space-multiplexing technique mainly uses layered space-time coding (LST) technique.Space-diversity technique transmit the same information (signal form, transmit time and frequency may be different) over different antennas. Using the signal processing algorithm, the receiver can achieves diversity gain even coding gain to improve the reliability of communication systems. STBC which is a simple coding technology has strong ability to eliminate the interferences. It adopts maximum likelihood decoding algorithm to obtain fully diversity gain, thus can improve the system BER performance. The space-multiplexing technique converts the original data stream to multiple parallel data streams, and transmits the data streams at different antennas by the LST coding, which more directly reflects the essence of MIMO improving the spectrum efficiency. Space-multiplexing technique earliest was proposed by Bell Laboratory Foschini in 1996, therefore the layered space-time structure is usually refered as BLAST. Up to now, the vertical layered space-time structure (VLST), the horizontal layered space-time structure (HLST), the diagonal layered space-time structure (DLST) and twist layered space-time structure (TLST) have been put forward, where the VBLAST technique is widely adopted in space-time multiplexing systems.How to maintain both the merits of STBC reducing BER and VBLAST improving spectrum efficiency has important research value. The previous study have presented the algorithms that use STBC coding in the first layer of VBLAST signal, then together with other layers'signals are transmitted parallelly at multiple antennas, so it can only improve the first VBLAST signal layer decoding anti-jamming performance. This paper proposes the STBC and VBLAST hybrid coding technique, which uses STBC coding on several VBLAST layers. In the hybrid coding system, those antennas with the least contribution to the system capacity are selected to send multilayer STBC signals according to the antenna selection algorithm which is based on maximal capacity of antenna subset, so the system capacity loss caused by STBC coding is reduced. Both theoretical analysis and simulation results indicate that using the proposed antenna selection algorithm in STBC and VBLAST hybrid systems, not only greatly weaken the capacity loss caused by the STBC coding, but also retain the low BER merits of STBC coding.