多用户MIMO块对角化系统的差分酉空时调制

Multiuser MIMO block diagonalization system with differential unitary space-time modulation

针对下行多用户MIMO块对角化系统,用户端的等效信道与其他用户的零空间矩阵有关的问题,提出将块对角化和差分酉空时调制相结合的系统.该系统克服了传统的块对角化系统中基站需要准确告知每个用户各自接收矩阵或频繁发送导频的问题;基站得到零空间矩阵后,不需要对等效信道进行奇异值分解、功率分配等复杂操作;同时用户接收端也不需要估计信道.仿真给出了该系统与传统块对角化的收发结合系统在理想信道和瑞利信道下的性能比较.由于低的复杂度和较好的BER性能,所提系统适用于实际实施,尤其适用于多普勒频偏较小的慢变信道.

In order to solve the problem that each user＇s equivalent channel relates to all other users＇ null space in the downlink multiuser MIMO system with block diagonalization, a system combining block diagonalization and differential unitary space-time modulation was proposed. In the proposed system, the base station （BS） can avoid the accurate transmission of the receiving matrix or frequently transmitting pilots in the traditional block diagonalization. Neither the singular value decomposition （SVD） of the equivalent channel nor the power allocation is needed in the BS, once it obtains the nulling matrices. Moreover, users needn＇t estimate the channel. The performances of both our proposed system and the traditional joint Tx-Rx system were simulated for comparison in the ideal channel, as well as the Rayleigh channel with different doppler frequencies. For its low complexity and good BER performance, the proposed system is very suitable for implementation in practice especially in the slowly varying channel.