Beamforming techniques for nonorthogonal multiple access in 5G cellular networks

Faezeh Alavi*, Kanapathippillai Cumanan, Zhiguo Ding, Alister G. Burr

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


In this paper, we develop various beamforming techniques for downlink transmission for multiple-input single-output nonorthogonal multiple access (NOMA) systems. First, a beamforming approach with perfect channel state information is investigated to provide the required quality of service for all users. Taylor series approximation and semidefinite relaxation (SDR) techniques are employed to reformulate the original nonconvex power minimization problem to a tractable one. Furthermore, a fairness-based beamforming approach is proposed through a max-min formulation to maintain fairness between users. Next, we consider a robust scheme by incorporating channel uncertainties, where the transmit power is minimized while satisfying the outage probability requirement at each user. Through exploiting the SDR approach, the original nonconvex problem is reformulated in a linear matrix inequality form to obtain the optimal solution. Numerical results demonstrate that the robust scheme can achieve better performance compared to the nonrobust scheme in terms of the rate satisfaction ratio. Furthermore, simulation results confirm that NOMA consumes a little over half transmit power needed by orthogonal multiple access for the same data rate requirements. Hence, NOMA has the potential to significantly improve the system performance in terms of transmit power consumption in future 5G networks and beyond.

Original languageEnglish
Article number8411153
Pages (from-to)9474-9487
Number of pages14
JournalIEEE Transactions on Vehicular Technology
Issue number10
Publication statusPublished - Oct 2018

Bibliographical note

Funding Information:
Manuscript received October 23, 2017; revised March 10, 2018 and June 18, 2018; accepted July 4, 2018. Date of publication July 16, 2018; date of current version October 15, 2018. The work of all authors was supported by H2020-MSCARISE-2015 under grant number 690750. The work of Z. Ding was also supported by the UK Engineering and Physical Sciences Research Council (EPSRC) under grant number EP/ L025272/1. The review of this paper was coordinated by Dr. N.-D. Dao. (Corresponding author: Faezeh Alavi.) F. Alavi, K. Cumanan, and A. G. Burr are with the Department of Electronic Engineering, University of York, York YO10 5DD, U.K. (e-mail:, sa1280@; [email protected]; [email protected]).

Publisher Copyright:
© 1967-2012 IEEE.


  • max-min fairness
  • Non-orthogonal multiple access (NOMA)
  • outage probability
  • robust beamforming

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