217 research outputs found
Optimal Throughput Fairness Trade-offs for Downlink Non-Orthogonal Multiple Access over Fading Channels
Recently, non-orthogonal multiple access (NOMA) has attracted considerable
interest as one of the 5G-enabling techniques. However, users with better
channel conditions in downlink communications intrinsically benefits from NOMA
thanks to successive decoding, judicious designs are required to guarantee user
fairness. In this paper, a two-user downlink NOMA system over fading channels
is considered. For delay-tolerant transmission, the average sum-rate is
maximized subject to both average and peak power constraints as well as a
minimum average user rate constraint. The optimal resource allocation is
obtained using Lagrangian dual decomposition under full channel state
information at the transmitter (CSIT), while an effective power allocation
policy under partial CSIT is also developed based on analytical results. In
parallel, for delay-limited transmission, the sum of delay-limited throughput
(DLT) is maximized subject to a maximum allowable user outage constraint under
full CSIT, and the analysis for the sum of DLT is also performed under partial
CSIT. Furthermore, an optimal orthogonal multiple access (OMA) scheme is also
studied as a benchmark to prove the superiority of NOMA over OMA under full
CSIT. Finally, the theoretical analysis is verified by simulations via
different trade-offs for the average sum-rate (sum-DLT) versus the minimum
(maximum) average user rate (outage) requirement.Comment: 35 pages, 10 figures, 3 tables, the longer version of the paper with
the same titl
On secure system performance over SISO, MISO and MIMO-NOMA wireless networks equipped a multiple antenna based on TAS protocol
This study examined how to improve system performance by equipping multiple antennae at a base station (BS) and all terminal users/mobile devices instead of a single antenna as in previous studies. Experimental investigations based on three NOMA down-link models involved (1) a single-input-single-output (SISO) scenario in which a single antenna was equipped at a BS and for all users, (2) a multi-input-single-output (MISO) scenario in which multiple transmitter antennae were equipped at a BS and a single receiver antenna for all users and (3) a multi-input-multi-output (MIMO) scenario in which multiple transmitter antennae were equipped at a BS and multiple receiver antenna for all users. This study investigated and compared the outage probability (OP) and system throughput assuming all users were over Rayleigh fading channels. The individual scenarios also each had an eavesdropper. Secure system performance of the individual scenarios was therefore also investigated. In order to detect data from superimposed signals, successive interference cancellation (SIC) was deployed for users, taking into account perfect, imperfect and fully imperfect SICs. The results of analysis of users in these three scenarios were obtained in an approximate closed form by using the Gaussian-Chebyshev quadrature method. However, the clearly and accurately presented results obtained using Monte Carlo simulations prove and verify that the MIMO-NOMA scenario equipped with multiple antennae significantly improved system performance.Web of Science20201art. no. 1
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