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Nonorthogonal Random Access for 5G Mobile Communication Systems


Abstract:

This correspondence paper proposes two nonorthogonal random access (NORA) techniques for 5G mobile communication networks, where user equipments (UEs) make use of the cha...Show More

Abstract:

This correspondence paper proposes two nonorthogonal random access (NORA) techniques for 5G mobile communication networks, where user equipments (UEs) make use of the channel inversion technique such that their received power at the base station (BS) can be one of the two target values. It enables the BS to decode two packets simultaneously with the successive interference cancellation (SIC) technique if a different power level is chosen. We propose two NORA systems; that is, UEs choose one of the two target power levels based on the channel gain or the region where they are. The performance of the proposed systems is analyzed in terms of access delay, throughput, and energy efficiency. Through analysis and extensive computer simulations, we show that the maximum throughput of the proposed NORA techniques can exceed 0.7, which is a significant improvement compared to the maximum throughput of conventional random access 0.368.
Published in: IEEE Transactions on Vehicular Technology ( Volume: 67, Issue: 8, August 2018)
Page(s): 7867 - 7871
Date of Publication: 12 April 2018

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I. Introduction

To improve the spectral efficiency (SE) for the 5th generation (5G) mobile communication systems, non-orthogonal multiple access (NOMA) has been proposed [1], in which the receiver separates the super-imposed signals via successive interference cancellation (SIC) technique. When it is used for the downlink, a base station (BS) constructs the super-imposed signal for a group of users in the same radio resource and allocates different transmission powers to each user equipment (UE). The multiplexed signal experiences the same (small-scale) fading and path-loss collectively over the downlink, and then it can be successfully separated by each UE with SIC technique if the BS properly allocates different levels of powers to the UEs. For the uplink, in contrast, the BS receives the super-imposed signals from different UEs, each of which may experience independent fading and path-loss due to their different locations.

References

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