Linear Transceiver Design for Full-Duplex Multi-Cell MIMO Systems

Ali Cagatay Cirik, Omid Taghizadeh, Lutz Lampe, Rudolf Mathar, Yingbo Hua
2016 IEEE Access  
We consider a multi-cell multiple-input multiple-output full-duplex (FD) system, where multiple FD capable base stations (BSs) serve multiple mobile users operating in FD mode. The selfinterference at the BSs and users, and co-channel interference (CCI) between all the nodes (BSs and users) in the system are both taken into account. We consider the transmit and receive filter design for sum-rate maximization problem subject to sum-power constraints at the BSs and individual power constraints at
more » ... each user of the system under the limited dynamic range considerations at the transmitters and the receivers. By reformulating this non-convex problem as an equivalent multi-convex optimization problem with the addition of two auxiliary variables, we propose a low complexity alternating algorithm that converges to a stationary point. Since this sum-rate maximization results in starvation of users in terms of resources depending on the power of the self-interference and CCI channels, we modify the sum-rate maximization problem by adding target data rate constraints on each user, and propose an algorithm based on Lagrangian relaxation of the rate constraints. INDEX TERMS Full-duplex, MIMO, multi-cell, self interference, transceiver designs. I. INTRODUCTION In current half-duplex (HD) cellular systems, uplink (UL) and downlink (DL) channels are designed to operate in either separate time slots or separate frequency bands, resulting in inefficient usage of the radio resources. Full-duplex (FD) systems, which enable simultaneous transmission and reception at the same time in the same frequency band, have recently gained considerable interest, e.g., for their potential to improve spectral efficiency of the next generation wireless communication systems [1]- [5] . The introduction of FD base-stations (BSs) introduce not only self-interference, but also co-channel interference (CCI) from UL users to DL users. FD communication has been investigated for single cell systems in [6]- [8] . However the authors in [6]-[8] ignore several fundamental impediments of FD systems, i.e. transmitter and receiver distortion caused by non-ideal amplifiers, oscillators, analog-to-digital converters (ADCs), and digital-to-analog converters (DACs), etc. [9] and thus several system parameters were ideally assumed. In this paper, we consider a multi-cell FD multipleinput multiple-output (MIMO) scenario where FD capable BSs communicate with mobile users operating in FD mode at the same time slot over the same frequency band. In addition to self-interference channel at the BSs and users, the CCI between all the nodes in the system is also taken into account, which increases the difficulty of the optimization problem further. The sum-rate maximization problem for this system subject to sum-power constraints at the BSs and individual power constraints at each user of the system is studied under the practical FD impairments. By introducing two auxiliary variables, the non-convex sum-rate maximization problem is reformulated as an equivalent multi-convex problem [10], [11] , and a low complexity algorithm that converges to a stationary point is developed. In [8] and [12], sum-rate maximization problem in FD single-cell MIMO systems has been considered, where the relationship between weighted-sumrate and weighted minimum-mean-squared-error (WMMSE) problems [13] , [14] is exploited to solve the sum-rate maximization problem. Different from [8] and [12] , where this relationship only holds when the receivers employ minimummean-squared-error (MMSE) receive filter, the proposed 4678 2169-3536
doi:10.1109/access.2016.2603439 fatcat:c55nsnfioncq3jo7tfrtas4bwe