Asynchronous Flipped Grant-Free SCMA for Satellite-Based Internet of Things Communication Networks

Applied Sciences

Weidong Wang¹  Gaofeng Cui¹  Pengxu Li¹ 

[1] School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China;

关键词: satellite communication networks;    IoT;    massive connectivity;    uplink multiple access;    asynchronous system;    flipped diversity;   

DOI  :  10.3390/app9020335

来源: DOAJ

【 摘 要 】

Sparse code multiple access (SCMA) is a promising code domain non-orthogonal multiple-access scheme which is able to support massive connectivity and grant-free transmission in future satellite-based Internet of Things (IoT) communication networks. Traditional grant-free SCMA is based on time synchronization, which is no longer favorable in such satellite communication networks since the amount of signaling generated to keep all transmitters’ time synchronized is impractical for large networks. Moreover, without centralized codebook assignment, grant-free SCMA suffers from codebook collisions which mean more than one terminal selecting the same codebook being interfered. Motivated by these issues, a novel uplink grant-free asynchronous flipped SCMA scheme named AF-SCMA is proposed in this paper. With the concept of flipped diversity, a specific SCMA-encoded packet is transmitted with its flipped replica together. Successive interference cancellation technique combined with a sliding window is adopted to resolve the packet collisions including codebook collisions at the gateway station. The performance of AF-SCMA is investigated via both mathematical analysis and simulations. Simulation results show that the proposed AF-SCMA provides remarkable performance in terms of throughput and packet loss ratio (PLR), and can benefit from the received signal power unbalance.

【 授权许可】

Unknown