Yu, W. and Musavian, L. and Quddus, A.U. and Ni, Q. and Xiao, P. (2018) Low Latency Driven Effective Capacity Analysis for Non-Orthogonal and Orthogonal Spectrum Access. In: 2018 IEEE Globecom Workshops (GC Wkshps) :. IEEE. ISBN 9781538649206
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Abstract
In this paper, we theoretically investigate the performance of non-orthogonal and orthogonal spectrum access protocols (more generically known as NOMA) in supporting ultra-reliable low-latency communications (URLLC). The theory of effective capacity (EC) is adopted as a suitable delay-guaranteed capacity metric to flexibly represent the users' delay requirements. Then, the total EC difference between a downlink user-paired NOMA network and a downlink orthogonal multiple access (OMA) network is analytically studied. Exact closed-form expressions and the approximated closed-forms at high signal-to-noise ratios (SNRs) are derived for both networks and validated through simulation results. It is shown that for a user pair in which two users with the most distinct channel conditions are paired together, NOMA still achieves higher total EC (compared to OMA) in high SNR regime as the user group size becomes larger, although the EC performance of both NOMA and OMA reduces with the increase in group size. It is expected that the derived analytical framework can serve as a useful reference and practical guideline for designing favourable orthogonal and nonorthogonal spectrum access schemes in supporting low-latency services.