Abstract

In this letter, we propose a robust beamforming design for non-orthogonal multiple access (NOMA) based multiple-input single-output (MISO) downlink systems. In particular, the robust power minimization problem is studied with imperfect channel state information (CSI), where the beamformers are designed by incorporating norm-bounded channel uncertainties to provide the required quality of service at each user. This robust scheme is developed based on the worst-case performance optimization framework. In terms of beamforming vectors, the original robust design is not convex and therefore, the robust beamformers cannot be obtained directly. To circumvent this non-convex issue, the original intractable problem is reformulated into a convex problem, where the non-convex constraint is converted into a linear matrix inequality (LMI) by exploiting S-Procedure. Finally, simulation results are provided to demonstrate the effectiveness of the proposed robust design.

Highlights

  • Non-orthogonal multiple access (NOMA) is a promising multiple access technique for 5G networks which has the potential to address the issues associated with the exponential growth of data traffic such as spectrum scarcity and massive connectivity [10], [11], [13], [15], [19]

  • Motivated by this practical constraint, we focus on robust beamforming design based on the worst-case performance optimization framework to tackle the norm-bounded channel uncertainties [4], [16], [18], [20]

  • In the non-orthogonal multiple access (NOMA) scheme, user multiplexing is performed in the power domain and the successive interference cancellation (SIC) approach is employed at receivers to separate signals between different users

Read more

Summary

INTRODUCTION

By incorporating the bounded channel uncertainties, the robust sum power minimization problem is investigated in [20] for a downlink multicell network with the worst-case signal-to-interference-plus-noiseratio (SINR) constraints whereas the robust weighted sumrate maximization was studied for multicell downlink MISO systems in [16]. A single beamformer is designed to transmit the signals for all users in the same cluster whereas, in this letter, the signal for each user is transmitted with a dedicated beamformer Both beamforming designs are completely different as the work in [22] proposes robust sum-rate maximization based design whereas this letter solves robust power minimization problem with rate constraint on each user. The work in [22] and the proposed work in this letter are different including problem formulation and the solution approaches

SYSTEM MODEL AND PROBLEM FORMULATION
ROBUST BEAMFORMING DESIGN
SIMULATION RESULTS
CONCLUSION
3: If a block
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.