TY - JOUR
T1 - Optimal Throughput Fairness Tradeoffs for Downlink Non-Orthogonal Multiple Access over Fading Channels
AU - Xing, Hong
AU - Liu, Yuanawei
AU - Nallanathan, Arumugam
AU - Ding, Zhiguo
AU - Poor, H. Vincent
N1 - Funding Information:
Manuscript received August 8, 2017; revised December 1, 2017; accepted January 20, 2018. Date of publication March 21, 2018; date of current version June 8, 2018. This work was supported in part by the Engineering and Physical Sciences Research Council of the U.K. under Grant EP/N005651/2 and in part by the U.S. National Science Foundation under Grant CNS-1702808 and Grant ECCS-1647198. This paper was presented in part at the IEEE Wireless Communications and Networking Conference, Barcelona, Spain, April 2018 [1]. The associate editor coordinating the review of this paper and approving it for publication was D. W. K. Ng. (Corresponding author: Hong Xing.) H. Xing, Y. Liu, and A. Nallanathan are with the School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, U.K. (e-mail: [email protected]; [email protected]; [email protected]).
Publisher Copyright:
© 2002-2012 IEEE.
PY - 2018/6
Y1 - 2018/6
N2 - Recently, non-orthogonal multiple access (NOMA) has attracted considerable interest as one of the 5G-enabling techniques. However, the users with better channel conditions in downlink communications intrinsically benefit more from NOMA than the users with worse channel conditions 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 the 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 tradeoffs for the average sum rate (sum-DLT) versus the minimum (maximum) average user rate (outage) requirement.
AB - Recently, non-orthogonal multiple access (NOMA) has attracted considerable interest as one of the 5G-enabling techniques. However, the users with better channel conditions in downlink communications intrinsically benefit more from NOMA than the users with worse channel conditions 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 the 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 tradeoffs for the average sum rate (sum-DLT) versus the minimum (maximum) average user rate (outage) requirement.
KW - ergodic rate
KW - fading channel
KW - fairness
KW - Lagrangian dual decomposition
KW - Non-orthogonal multiple access
KW - orthogonal multiple access
KW - outage probability
KW - strong duality
UR - http://www.scopus.com/inward/record.url?scp=85044302307&partnerID=8YFLogxK
U2 - 10.1109/TWC.2018.2803177
DO - 10.1109/TWC.2018.2803177
M3 - Article
AN - SCOPUS:85044302307
SN - 1536-1276
VL - 17
SP - 3556
EP - 3571
JO - IEEE Transactions on Wireless Communications
JF - IEEE Transactions on Wireless Communications
IS - 6
ER -