Cooperative communication networks have been studied and analyzed for many years for enhancing system performance,capacity,and reducing interference with the least focus on handover in cooperative communication scenarios.This paper focuses on trial field testing system for evaluating the proposed handover scheme called slide handover(HO).An automatic power allocation technique is coupled with slide HO scheme and its performance is also evaluated under cooperative networks.Our proposed scheme has achieved 100%successful HO executions in our field trial system.Block error rate(BLER)and slide HO are tested and analyzed in this trial system,and it is shown that the capacity of cooperative networks in these trials implementation has improved and maintained the expected quality of service.BLER below1%is noted at different testing locations which occasionally reached to 10%.Real-time video streaming performance is tested at different trial locations,and uniform streaming performance is noted at all different locations including during the HO process.This implies the improved HO delay of the proposed slide HO as compared to traditional HO techniques.
Xiaofeng TaoDezhuang WuWaheed Ur RehmanYue YinZhiling Tang
极化码与混合自动请求重传结合的传输方案适用于物联网应用的短数据包场景。现有的极化码与蔡司合并结合的传输方案能够提供合并增益,但并未提供编码增益。极化码与增量冗余结合的传输方案能够获得更好的性能,但计算复杂度较高,不适用于短数据包场景。该文提出一种改进型极化码与混合自动请求重传结合的传输方案。与现有的极化码与蔡司合并结合的传输方案相比,当码率为1/2、重传次数为1时,该方案能够获得额外的0.7 d B的编码增益,与码率为1/4的极化码性能相近。该文所提方案的编译码复杂度相比于码率为1/4的极化码,降低了50%的复杂度。仿真结果验证了该方案的有效性。
In order to support massive Machine Type Communication(mMTC) applications in future Fifth Generation(5G) systems,a key technical challenge is to design a highly effective multiple access protocol for massive connection requests and huge traffic load from all kinds of smart devices,e.g.bike,watch,phone,ring,glasses,shoes,etc..To solve this hard problem in distributed scenarios with massive competing devices,this paper proposes and evaluates a Neighbor-Aware Multiple Access(NAMA) protocol,which is scalable and adaptive to different connectivity size and traffic load.By exploiting acknowledgement signals broadcasted from the neighboring devices with successful packet transmissions,NAMA is able to turn itself from a contention-based random access protocol to become a contention-free deterministic access protocol with particular transmission schedules for all neighboring devices after a short transition period.The performance of NAMA is fully evaluated from random state to deterministic state through extensive computer simulations under different network sizes and Contention Window(CW)settings.Compared with traditional IEEE802.11 Distributed Coordination Function(DCF),for a crowded network with 50 devices,NAMA can greatly improve system throughput and energy efficiency by more than 110%and210%,respectively,while reducing average access delay by 53%in the deterministic state.
Yang YangGuannan SongWuxiong ZhangXiaohu GeChengxiang Wang
