A Novel HARQ Scheme for SCMA Systems

This letter considers the hybrid automatic repeat request (HARQ) scheme for sparse code multiple access (SCMA) systems, where the message passing algorithm (MPA) is adopted in the multiuser detection. In MPA, the reliability can be improved when parts of messages are pre-known. Motivated by this fact, a novel HARQ scheme for SCMA systems is proposed, where some correctly decoded codewords are still retransmitted in the next round of transmission. Analysis and simulation results show that, compared with the traditional HARQ scheme, the reliability of the proposed scheme is enhanced obviously, while the latency increases slightly. Hence, in the proposed scheme, an affordable tradeoff between the reliability and latency can be achieved.

[1]  Min Sheng,et al.  Rate and Energy Maximization in SCMA Networks With Wireless Information and Power Transfer , 2016, IEEE Communications Letters.

[2]  Xiaodong Wang,et al.  Efficient combining techniques for multi-input multi-output multi-user systems employing hybrid automatic repeat request , 2011, IET Commun..

[3]  Ling Qiu,et al.  Capacity for downlink massive MIMO MU-SCMA system , 2015, 2015 International Conference on Wireless Communications & Signal Processing (WCSP).

[4]  Pingzhi Fan,et al.  A Fixed Low Complexity Message Pass Algorithm Detector for Up-Link SCMA System , 2015, IEEE Wireless Communications Letters.

[5]  Pingzhi Fan,et al.  An SCMA-based uplink inter-cell interference cancellation technique for 5G wireless systems , 2015, 2015 International Conference on Wireless Communications & Signal Processing (WCSP).

[6]  Shu Lin,et al.  Error control coding : fundamentals and applications , 1983 .

[7]  Alireza Bayesteh,et al.  SCMA for Open-Loop Joint Transmission CoMP , 2015, 2015 IEEE 82nd Vehicular Technology Conference (VTC2015-Fall).

[8]  Hosein Nikopour,et al.  Sparse code multiple access , 2013, 2013 IEEE 24th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC).