重构MBSFN子帧，在R9/10终端低渗透率下提升频谱效率

(1)目的:降低LTE DMRS引入的约10%频谱开销,提升频谱利用率;LTE DMRS的引入,提升终端下行解调能力;DMRS与PDSCH同时进行预编码,PMI信息更丰富,支持MU-MIMO,同时支持不依赖RRC信令的功率实时调整;但是DMRS会引入10%的频谱开销,从而降低了频谱利用率;(2)方法:开启MBSFN子帧,并重构,在调度R8用户的频谱位置构造非MBSFN子帧格式;MBSFN子帧中PDSCH信道不需要CRS,从而可以抵消DMRS引入的频谱开销;但是基于3GPP协议描述,只有R9/10用户才能识别MBSFN子帧;如果在R9/10终端低渗透率的场景下开启MBSFN,会造成该子帧不能调度R8用户,降低频谱效率。(3)结果:通过仿真对比,常规MBSFN子帧的开启,需要在R8/9终端渗透60%,才能保证频谱效率不降低,而重构MBSFN子帧场景下,在R8/9终端渗透低于60%下,开启MBSFN子帧可以提升频谱效率。(4)结论:在R8/9终端渗透率低的情况下,通过重构MBSFN子帧,提升系统频谱效率。

(1). Purpose: To reduce the spectrum overhead of LTE DMRS and improve spectrum utilization;LTE DMRS is introduced to improve terminal downlink demodulation capability;DMRS and PDSCH are pre-coded at the same time, PMI information is more abundant, and MU is supported.-MIMO, which supports real-time power adjustment without RRC signaling;however, DMRS introduces 10% spectrum overhead, which reduces spectrum utilization;(2). Method: Enable MBSFN sub-frames, and reconstruct, in scheduling R8 users The spectrum location constructs a non-MBSFN sub-frame format;the PDSCH channel in the MBSFN sub-frame does not require CRS, thereby canceling the spectrum overhead introduced by the DMRS;but based on the 3 GPP protocol description, only the R9/10 user can identify the MBSFN sub-frame;if at R9/When the MBSFN is enabled in the scenario where the terminal is in a low-permission rate, the sub-frame cannot schedule R8 users and reduce the spectrum efficiency.(3). Result: Through simulation comparison, the opening of the regular MBSFN subframe needs to penetrate 60% in the R8/9 terminal to ensure that the spectrum efficiency does not decrease. In the scenario of reconstructing the MBSFN sub-frame, the penetration in the R8/9 terminal is lower than that. At 60%, enabling MBSFN sub-frames can improve spectrum efficiency.(4). Conclusion: In the case of low R8/9 terminal penetration rate, the spectrum efficiency of the system is improved by reconstructing MBSFN sub-frames.