Active-user Detection And Group D2D Communications In A Layered Grouping Random Access Scheme

In the upcoming new stage of wireless communications,the type of communication is no longer limited to the traditional Human to Human(H2H)or Human to Device(H2D).Instead,massive machine type communications(mMTC)have been identified as an important issue in Beyond 5G networks and future massive Internet of Things(mIoT).Therefore,much higher overhead and collision problem will occur if we still employ the conventional 4-step random access(RA)scheme.Consequently,this thesis will focus on a new layered grouping random access scheme.Other techniques such as group-paging and D2D communications are also employed to effectively overcome the challenges brought about by mMTC scenarios.First of all,based on the analysis of the existing RA mechanisms,cooperating with my scholar partner,a layered grouping RA strategy for the massive connectivity of IoT is proposed,where the cellular devices are divided into clusters and groups.With this new layered grouping cellular architecture,the RA process is separated into cluster load estimation phase and active group detection phase.Based on our research,under the limited resource allocation,the proposed two-phases RA scheme is able to support a much larger number of potential users while greatly reducing the access energy consumption.Furthermore,the fundamental techniques especially the active-user detection and the deterministic sequence-based AMP algorithm are studied to support the layered grouping structure and two-phases RA procedure.In addition,based on the corresponding simulation results of MATLAB platform,the access rate and the number of potential devices supported in the cellular area are analyzed.On the basis of the layered grouping RA structure,a multi-hop communication scheme based on the inter-group D2D communication is proposed.With the aid of ?D-Interference Limited Area(?D-ILA)algorithm,an interference model between the inter-group and cellular communication is designed.Additionally,the relation between the number of users in the group and the size of the interference limited area as well as the improvement of the system capacity while applying the inter-group D2D communication are also analyzed.