Asynchronous uplink non-orthogonal multiple access (NOMA) with cyclic prefix

Non-orthogonal multiple access (NOMA) has been recognized as a promising technique for future radio access. In this paper, different from [3], it is proposed that the cyclic prefix (CP) is used in the asynchronous uplink NOMA transmission for mitigating asynchronous effects. Through analyzing the inter-user interference (IUI) and residual interference, it is shown that the asynchronism can degrade the uplink NOMA users' bit error rate (BER) performance severely for the conventional-successive interference cancellation (Conv-SIC) technique. By applying the SIC-phase compensation (SIC-PC) technique and CP, the asynchronous effects can be mitigated. The BER performance of near and far users can be improved substantially, compared with other existing successive interference cancellation (SIC) techniques.