Uplink Contention Based SCMA for 5G Radio Access

摘要

Fifth generation (5G) wireless networks are expected to support very diverseapplications and terminals. Massive connectivity with a large number of devicesis an important requirement for 5G networks. Current LTE system is not able toefficiently support massive connectivity, especially on the uplink (UL). Amongthe issues arise due to massive connectivity is the cost of signaling overheadand latency. In this paper, an uplink contention-based sparse code multipleaccess (SCMA) design is proposed as a solution. First, the system designaspects of the proposed multiple-access scheme are described. The SCMAparameters can be adjusted to provide different levels of overloading, thussuitable to meet the diverse traffic connectivity requirements. In addition,the system-level evaluations of a small packet application scenario areprovided for contention-based UL SCMA. SCMA is compared to OFDMA in terms ofconnectivity and drop rate under a tight latency requirement. The simulationresults demonstrate that contention-based SCMA can provide around 2.8 timesgain over contention-based OFDMA in terms of supported active users. The uplinkcontention-based SCMA scheme can be a promising technology for 5G wirelessnetworks for data transmission with low signaling overhead, low delay, andsupport of massive connectivity.