基于大规模MIMO和D2D技术的混合网络能量效率研究

Research on Energy Efficiency of Hybrid Networks Based on Massive MIMO and D2D

  • 摘要: 文章研究了基于大规模多输入多输出(multiple-input multiple-output,MIMO)和端到端(device-to-device,D2D)技术的双层混合网络及其能量效率,面向D2D用户(D2D user,DU)提出了无线能量采集方案。在该混合网络模型中,宏蜂窝基站由大规模MIMO天线阵列构成,D2D网络覆盖在宏蜂窝之上,与蜂窝网共享频谱。为了保证D2D通信,系统配置了由小规模MIMO天线构成的专用能量发射基站(power beacon,PB),其通过迫零预编码向能量约束的D2D发射机传送能量;同时,为了提高网络的能量效率,DU还可以从附近蜂窝网用户(cellular user,CU)的射频(radio frequency,RF)干扰信号中采集能量。对此混合网模型和能量采集方案,文章通过假设网络中CU、DU以及PB的位置服从独立泊松点过程和利用随机几何分析方法,基于反功率控制方案得到了网络中任一D2D发射机通过采集足够能量来建立通信链路的概率,其以简单的积分形式给出。分析和数值结果表明,文章提出的无线能量采集方案由于PB的配置保证了D2D通信的可靠性;同时又因为充分利用了附近CU的RF干扰信号,有效提高了D2D用户采集足够能量的概率,节约了PB的能量,改善了系统的能量效率。

     

    Abstract: In this paper, based on massive MIMO and device-to-device (D2D) techniques, a two-tier hybrid network is considered as well as the energy efficiency analysis, and a novel wireless energy-harvesting scheme for DUs (D2D users) is proposed. In the interested hybrid networks, the base stations of macro cells are equipped with massive MIMO antenna array. The macro cells are overlaid by D2D networks and share spectrum with D2D. To guarantee D2D communications, the dedicated power beacons (PBs) are deployed, which are equipped with small-scale MIMO. By using zero-forcing precoding scheme, the dedicated PBs transfer energy for energy-constrained D2D transmitters. At the same time, in order to improve the energy efficiency of the networks, the DUs also harvest the energy from the ambient radio frequency (RF) interference of cellular users (CUs). For the proposed hybrid network models and energy-harvesting schemes, we model the positions of CUs, DUs, and PBs are the independently Poisson point processes, respectively. By applying stochastic geometry, based on inverse power control scheme we derive the sufficient probability that a typical D2D transmitter harvests sufficient energy to establish communication links, which is presented in a simple integral form. Both the analytical and numerical results show that the proposed wireless energy-harvesting schemes not only guarantee the reliability of D2D communications by equipping PBs, but also improve the sufficient probability of DUs harvesting energy by exploiting the ambient RF interference of CUs. As a result, the power of PBs is saved, and the energy efficient of networks is improved greatly.

     

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