In this paper, we investigate the feasibility of applying Physical Layer Network Coding (PNC) in Multi-user Massive MIMO systems. In addition, we investigate the performance benefits of the joint Massive MIMO and PNC scheme. PNC has the potential of increasing capacity of a wireless system as the number of timeslots required for end-to-end communication reduces. We adopted a scheme that transforms the channel between a massive-antenna relay and a multitude of multi-antenna user terminals, with a Sum-Difference (SD) matrix. Through Log-Likelihood Ratio (LLR), PNC is achieved by deriving the network coded symbols from the estimates of the SD symbols at the massive-antenna relay node. The equalization matrix for the estimation is based on the SD transformed channel coefficient matrix. The error performance of the proposed joint Massive MIMO and PNC is evaluated through extensive simulation results. It is shown that joint Massive MIMO and PNC performs significantly better than Massive MIMO without PNC for QPSK modulation.

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Research aims: The study examined the effect of ownership structures on audit fees of listed firms in Ghana. The study used four indicators to measure ownership structure: managerial ownership, foreign ownership, government ownership, and substantial (block) ownership.Design/Methodology/Approach: The study sampled 21 listed non-financial firms over ten years, covering the period 2010 to 2019. The study also relied on secondary data extracted from the financial statement of these listed firms. Data were analyzed using descriptive statistics, correlation analysis, and panel regression analysis.Research findings: The study results showed a positive and significant association between foreign ownership and audit fees in Ghana. The study further found a positive and significant relationship between block ownership and audit fees. The results, however, uncovered an insignificant association between government ownership and audit fees. Furthermore, the study reported a positive coefficient between block ownership and audit fees, and the relationship was statistically significant.Theoretical contribution/Originality: The study is among very few studies that have examined ownership structures such as foreign ownership, managerial ownership, government ownership, and block ownership on audit fees in a developing country context and Ghana.Practitioner/Policy implication: This study found that the higher agency conflict through ownership structures will give rise to the higher audit fees paid to external auditors, which managers and auditors should consider in future assignments.Research limitation/implication: The study is limited by geographical area (Ghana), and as such future studies can conduct cross-country analysis of ownership structures on audit fees.

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In beyond 5G communications, besides energy efficiency (EE) and spectral efficiency (SE), latency and reliability, which are among the main metrics that extreme ultrareliable low-latency communications (URLLC) applications must fulfil. Although new techniques are sought after to meet the crunching requirements of URLLC, combining existing physicallayer techniques have become compelling, attractive and cost saving approach in achieving the same goal. In this paper, we describe a novel mechanism in combining Physical Layer Network Coding (PNC) and Index Modulation (IM) to achieving a balance between SE and EE for URLLC applications beyond 5G. PNC has the potential to increase SE because it leverages on interference from many transmissions occurring at the same time. Although fewer resources are required for IM, the capacity gain is the same as if all transmission resources are used, and as a result, both EE and SE can increase simultaneously. Our simulation results show the feasibility of combining these two key physical-layer techniques, affirming the complementary role this approach will play in meeting the performance KPIs of URLLC, beyond 5G.

In this paper, we investigate the resilience of Massive MIMO Physical Layer Network Coding (PNC) to jamming attack in both sub-6 GHz and millimeter-Wave (mmWave) systems in vehicular networks. Massive MIMO generally is resilient to jamming attacks, and we investigate the impact that PNC has on this resilience, if combined with Massive MIMO. The combination of Massive MIMO and PNC has shown a significant improvement in the bit error rate (BER) in our previous investigation. The corresponding framework is analysed against a barraging attack from a jammer, where the jamming channel is not known to the base station (BS), and the jammer can use any number of transmit antennas. Over Rayleigh channel, our simulation results reveal that Massive MIMO PNC performs better in the lower signal-to-noise ratio (SNR) regions to jamming attacks and this is achieved at twice the spectral efficiency. A similar performance is observed over mmWave channel.

Non-orthogonal multiple access (NOMA) based multiple-input multiple-output (MIMO), which has the potential to provide both massive connectivity and high spectrum efficiency, is considered as one of the efficient techniques for sixth generation (6G) wireless systems. In massive Internet of Things (IoT) networks, user-set selection is crucial for enhancing the overall performance of NOMA based systems when compared with orthogonal multiple access (OMA) techniques. In this paper, we propose a user-set selection algorithm for IoT uplink transmission to improve the sum data rate of the NOMA based MIMO systems. In order to exchange data between the selected IoT pairs, we propose to employ wireless physical layer network coding (PNC) to further improve the spectral efficiency and reduce the delay to fulfill the requirements of future IoT applications. Performance evaluations are provided based on both sum data rate and bit error rate for the proposed NOMA based MIMO with PNC in the considered massive IoT scenarios.