Performance of Dual-Polarized MIMO for TD-HSPA Evolution Systems

As the migration from code division multiple access (CDMA) to orthogonal frequency-division multiple access (OFDMA) involves a technological revolution in physical layer, the high speed packet access (HSPA) evolution (HSPA+) has been proposed for a smooth migration. HSPA+ is an effort to further improve radio performance of HSPA, and wideband CDMA (WCDMA) HSPA+ and time division-synchronous CDMA (TD-SCDMA) HSPA+ (TD-HSPA+) are two HSPA+ systems evolving from WCDMA and TD-SCDMA, respectively. Different from WCDMA HSPA+ system, TD-HSPA+ system utilizes eight antennas at Node B and two antennas at user equipment (UE) for 8 x 2 Multi-Input and Multi-Output (MIMO) transmission to achieve antenna array gain and diversity gain. Furthermore, to facilitate 8 x 2 MIMO configuration, the antenna elements are partitioned into two groups for dual-polarization transmissions. This paper focuses on 8 x 2 MIMO schemes in TD-HSPA+ systems, including the traditional single polarized MIMO (SP-MIMO), the separated and the joint singular value decomposition (SVD) based precoding dual-polarized MIMO (DP-MIMO) schemes. Performances of these TD-HSPA+ MIMO schemes are evaluated for both urban macro and micro scenarios. The simulation results show that the separated SVD based precoding DP-MIMO scheme performs better than the joint SVD based precoding DP-MIMO scheme, and the DP-MIMO scheme offers almost the same performance as the SP-MIMO due to the beamforming diversity gain and multiplex gain in TD-HSPA+ systems.