Abstract
This paper investigates the performance of improper Gaussian signaling (IGS) for the K-user multiple-input, multiple-output (MIMO) interference channel (IC) with hardware impairments (HWI). HWI may arise due to imperfections in the devices like I/Q imbalance, phase noise, etc. With I/Q imbalance, the received signal is a widely linear transformation of the transmitted signal and noise. Thus, the effective noise at the receivers becomes improper, which means that its real and imaginary parts are correlated and/or have unequal powers. IGS can improve system performance with improper noise and/or improper interference. In this paper, we study the benefits of IGS for this scenario in terms of two performance metrics: achievable rate and energy efficiency (EE). We consider the rate region, the sum-rate, the EE region and the global EE optimization problems to fully evaluate the IGS performance. To solve these non-convex problems, we employ an optimization framework based on majorization-minimization algorithms, which allow us to obtain a stationary point of any optimization problem in which either the objective function and/or constraints are linear functions of rates. Our numerical results show that IGS can significantly improve the performance of the K-user MIMO IC with HWI and I/Q imbalance, where its benefits increase with the number of users, K, and the imbalance level, and decrease with the number of antennas.
Highlights
Wireless communication devices are never completely ideal in practice, which can significantly degrade the system performance especially when the hardware non-idealities are not adequately modeled and accounted for the system design
Our numerical results show that improper Gaussian signaling (IGS) can significantly improve the performance of the K-user MIMO interference channel (IC) with hardware impairments (HWI) and I/Q imbalance, where its benefits increase with the number of users, K, and the imbalance level, and decrease with the number of antennas
Our results show that IGS can improve the performance of the K-user MIMO IC with HWI in terms of achievable rate and EE
Summary
Wireless communication devices are never completely ideal in practice, which can significantly degrade the system performance especially when the hardware non-idealities are not adequately modeled and accounted for the system design. The papers [6]–[8] studied secure communications for massive MIMO systems with AHWD in different scenarios. The papers [10]– [12] studied the performance of massive MIMO systems with AHWD in fading channels in different scenarios. In [14], the authors considered beamforming designs for a dual-hop massive MIMO amplify-and-forward relay channel in the presence of AHWD and analyzed the outage probabilities for the system. The same behavior is observed in [49], where PGS is proved to be optimal in the 2-user IC if coded time-sharing is allowed in which the average power consumption is constrained instead of the instantaneous power It seems that increasing the number of temporal or frequency dimensions provides a more flexible power allocation for PGS, which might lead to minor improvements by IGS. The following questions arise: how does IGS perform in the Kuser MIMO ICs? Is IGS still beneficial when the number of spatial dimensions (antennas) increases? In this paper, we answer these questions and analyze the performance of IGS by considering different rate and energy-efficiency metrics and solving various optimization problems
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