A Novel SCMA System for Coexistence of Active Users and Inactive Users

This letter proposes a new sparse code multiple access (SCMA) system for handling the coexistence of active user equipments (UEs) and inactive UEs, which share the same frequency/time resources for an uplink grant-free scenario. SCMA systems use a message passing algorithm, which considers all UEs to be active UEs. Therefore, inactive UEs cause significant decoding problem in SCMA systems. In order to solve the coexistence problem, we propose code words and a novel SCMA receiver which can distinguish the signal of active/inactive UEs. The numerical results show that the proposed SCMA receiver achieves a remarkable enhancement in false alarm probability, miss detection probability, and bit-error rate.

[1]  Jeffrey G. Andrews,et al.  What Will 5G Be? , 2014, IEEE Journal on Selected Areas in Communications.

[2]  Yan Chen,et al.  Iterative multiuser receiver in sparse code multiple access systems , 2015, 2015 IEEE International Conference on Communications (ICC).

[3]  Rahul Shrestha,et al.  Design and implementation of multi-rate LDPC decoder for IEEE 802.16e wireless standard , 2014, 2014 International Conference on Green Computing Communication and Electrical Engineering (ICGCCEE).

[4]  Alireza Bayesteh,et al.  SCMA Codebook Design , 2014, 2014 IEEE 80th Vehicular Technology Conference (VTC2014-Fall).

[5]  Shuangfeng Han,et al.  Non-orthogonal multiple access for 5G: solutions, challenges, opportunities, and future research trends , 2015, IEEE Communications Magazine.

[6]  Alireza Bayesteh,et al.  Blind detection of SCMA for uplink grant-free multiple-access , 2014, 2014 11th International Symposium on Wireless Communications Systems (ISWCS).