Space‐time block coding in millimeter wave large‐scale MIMO‐NOMA transmission scheme

Abstract

In this paper, we introduce a new wireless system architecture using space-time block coding schemes (STBC) and non-orthogonal multiple access (NOMA) in millimeter wave (mmWave) large-scale MIMO systems. The proposed STBC mmWave large-scale MIMO-NOMA system utilizes two MIMO subarrays, transmitting data over two channel vectors to mobile users.To reduce the communication overhead and latency in the system, we utilize random beamforming with optimal coefficients at the base station and random-near random-far user pairing in implementing the NOMA scheme.Our results show that the proposed STBC mmWave large-scale MIMO-NOMA technique significantly outperforms the previous counterparts. KEYWORDSMIMO, NOMA, mmWave, STBC, optimal beamforming INTRODUCTIONDue to the growing number of mobile users and the demand by the newly introduced machine-type communications (MTC), the next generation of wireless communication systems requires to support massive connectivity, and offers low latency with ultra communication reliability. 1,2 To support massive connectivity, the use of non-orthogonal multiple access (NOMA) techniques was introduced in Kim et al. 3 By applying superposition coding and successive interference cancellation (SIC), NOMA allows multiple users to access the same time-frequency resource, leading to further improvement in the spectral efficiency (SE) and massive connectivity compared to orthogonal multiple access (OMA). 4 It has also been shown that using NOMA in conjunction of multi-input multi-output (MIMO) structure can further enhance the SE. 5 User pairing plays a key role in improving the performance of NOMA systems. Recently, several different user pairing schemes were introduced in NOMA communication systems. 6 In Beyranvand et al., 7 three random user pairing techniques were proposed, all of which were based on the random distribution of users in a cell.Although random user pairing reduces the latency, it increases the outage probability (OP) compared to other pairing methods. 1,7,8 Chopra et al. 8 derived a closed-form expression that provides the optimal number of transmit antennas to minimize the OP of such systems. One of the aims of this letter is to introduce a system architecture to further reduce the OP in MIMO-NOMA structures. Beamforming and OP in mmWave massive MIMO systems have been discussed in Zeng et al. 9 In this paper, it is shown that the proposed system outperforms the conventional massive MIMO-OMA.In recent studies, it has been shown that the combination of NOMA and conventional STBC schemes can lead to substantial performance improvement. [10][11][12][13] Toka and Kucur, 10 investigated the performance of the Alamouti code in NOMA over Nakagami-m fading channels. Arti 14 proposed a space-time transmission scheme (STTS) for large-scale MIMO communication system. Int J Commun Syst. 2020;33:e4392.wileyonlinelibrary.com/journal/dac

Performance evaluation of Non‐Orthogonal multiple access system based on outage probability and power consumption

“…The NOMA system assigns different power level coefficients to users sharing resources 19 . In other words, optimal performance coefficients should be distributed to both the near and distant users 20 . The system should be improved by improving the power allocation coefficients and power sharing factor to ensure user fairness and increase the outage power of nearby users.…”

“…19 In other words, optimal performance coefficients should be distributed to both the near and distant users. 20 The system should be improved by improving the power allocation coefficients and power sharing factor to ensure user fairness and increase the outage power of nearby users. Therefore, these variables should be optimally selected to minimize the probability of failure by creating an objective function.…”