多载波码分多址系统联合特征码与子信道动态分配

Joint Spreading Sequence and Subchannel Dynamic Allocation in Multicarrier CDMA System

针对多载波码分多址系统中固定的子信道分配方案不能依据信道变化进行调整 ,而固定的扩频码分配又降低了系统的软容量等问题 ,本文在上行链路盲信道估计的基础上 ,提出下行链路联合特征码与子信道动态分配方案 .根据接入的用户数多少及各个用户的信道信息 ,进行联合码域与频域的动态资源分配 ,进一步降低了多址干扰 .数值仿真结果表明 ,本方案收敛快 ,信道跟踪性能好 ,在相同误码率条件下系统平均发射功率可以降低 3～ 4dB .

In multicarrier CDMA systems, the fixed subchannel allocation cannot update with the channel variety, so it degrades the system performance; and the fixed assignment of spreading sequence reduces the system soft-capacity. According to the above problems, a joint spreading sequence and subchannel dynamic allocation is proposed in forward link. By blind channel estimating of all users in reverse link, it assigns the spreading sequence and the subchannel adaptively. Because it dynamically assigns the resource both in frequency domain and code domain, it lessens the multiuser access interferences (MAI) further. Numerical simulations can illustrate that the proposed method has fast convergence and tracking character of blind channel estimation, and it has 3-4 dB save on transmission power at the same bit error rate.