大规模MIMO系统中用户分层变长时隙分配

Variable-length slots allocation for hierarchical users in the massive MIMO systems

大规模MIMO系统时分双工模式中分配的物理时隙长度是固定的,不能根据不同时长的信道相干时间灵活地调整长度,二者长度的不匹配导致部分时频资源的浪费,因此,系统的总体容量不能达到最优。针对此问题提出一种用户分层变长时隙分配方法,即根据不同终端的移动性对终端进行分层,并为不同层中的移动终端灵活地分配不同时长的物理时隙,使物理时隙长度与移动终端所对应信道的相干时长相匹配,从而减少时频资源的浪费,提高资源利用率。同时,避免了低速移动终端过频繁的信道估计,降低了信道训练序列开销,使系统的总体数据容量得到很大的提升。实验仿真结果验证了所提方法的有效性。

The length of physical slot is stationary in the time division duplex mode of the Massive MIMO system. Consequently,the length of the allocated physical slots cannot be adjusted according to different lengths of coherence intervals. The mismatch between slot and coherence leads to a waste of the time-frequency resource. Therefore,the whole network capacity of the system is not optimal. A variable-length slot allocation scheme based on hierarchical users was proposed to make the allocated physical slots match their corresponding coherence intervals well. In the proposed scheme,terminals were divided into different categories according to their mobility,and variable length slots were assigned to terminals in different categories flexibly. So the waste of time-frequency resource waste and the excessive channel estimation can be alleviated. The resource efficiency and the sum rate of the system are verified to be optimized and the simulation validates the proposed scheme.