| Multi-user MIMO relay system can provide additional space gains, can expand thecoverage of the wireless network, reduce the cost of the wireless access and reduce thecomplexity of the topological structure of the system. However, it must depends on thetechniques of the precoding and power allocation to optimize the performance ofmulti-user MIMO relay system. This paper therefore does a deep research around thejoint precoding and power allocation problems of base station and the relay, based onthe multi-user MIMO relay model of the next generation cellular wirelesscommunication system. The main purpose is to design a kind of feasible joint precodingand power allocation scheme for multi-user MIMO relay system with direct link andmeanwhile verify the feasibility of this system.This paper mainly focuses on the following aspects:1. In this paper we builds a multi-user MIMO relay system model with direct linkand studies the precoding and power allocation schemes of this model.2. Direct link in multi-user MIMO relay system encounters two problems:multi-user interference and complication of the signal transmission martrix. In order tosolve the two problems, this paper designs a kind of joint precoding scheme and apower allocation scheme to maximize the system capacity. This paper substantiallyreduces the computational complexity and obtains a sub-optimal solution. Thesimulation results show that the proposed optimization algorithm can effectivelysuppress multiuser interference and thus improve the system performance significantly.3. For the purpose to verify the realizability of the system in this paper, we usefinite alphabet to replace the conventional Gauss source. And we derive the capacity ofMIMO system with finite alphabet. Then we verify the feasibility of our system with thefinite alphabet. Through the simulation, we can conclude that the precoding and powerallocation scheme proposed in this paper can be applied in the finite alphabet very welland bring obvious performance gain. |
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