Trade‐offs between the quality of service, computational cost and cooling complexity in interference‐dominated multi‐user SDMA systems

Abstract

The future fifth generation (5G) systems will aim to design low-cost phased array base station antenna systems at mm-waves for simultaneous multiple beamforming with enhanced spatial multiplexing, limited interference, acceptable power consumption, suitable processing complexity, and passive cooling. In this study, a multiuser space division multiple access (SDMA) model is developed to investigate the trade-off between the quality of service (QoS), computational complexity in beamforming and cooling requirements for various use cases, and a number of users. The QoS at the user ends is rated by assessing the statistical signal-to-interference-plus-noise ratios (SINRs). Two beamforming algorithms, namely conjugate beamforming (CB) and zero-forcing (ZF), are considered and compared. Depending on the deployment scenario, rotated and optimised array layouts are proposed to be used in CB with the least computational complexity while providing relatively good QoS. Different reduced-complexity ZF algorithms are introduced as a compromise between the SINR performance and computational burden. The impact of the number of simultaneously served users on the thermal management in active integrated 5G base station antenna arrays is investigated as well.

Active Multiport Subarrays for 5G Communications

“…(D-ii) The number of simultaneously served far-away users (that need the gain from all the subarrays) is limited by the number of BM ports. However, in [32], it was shown that the number of users cannot be very large (K, P < 8 for the current chip technologies) due to the thermal management problems which is preferred to be handled passively via natural convection [33].…”

Exploitation of Triangular Lattice Arrays for Improved Spectral Efficiency in Massive MIMO 5G Systems

“…However, in [21] it was showed that a potential increase in the channel capacity can be obtained by exploiting an irregular antenna array layout. Planar array topologies based on irregular layouts have been designed by using convex optimization technique with the aim of decreasing the Peak-Side-Lobe-Level (PSLL) [22]- [25]. It has to be observed that the reduction of the PSLL by aperiodic arrangements is obtained by spreading the energy in a larger solid angle, thus raising the Average Side Lobe Level (ASLL) [26] with a consequent maximum array gain reduction.…”

Synthesis of Optimal 5G Array Layouts With Wide-Angle Scanning and Zooming Ability for Efficient Link Setup and High-QoS Communication

“…The introduction of the next generation communication network, with the potential use of the millimeter wave (mmwave) frequencies for high-throughput, brings up many severe system challenges including, but not limited to, the increased product cost, implementation complexity, processing burden and heat generation [1]. Although it is foreseen that digital beamforming solutions will prevail in the future due to their ability to provide the most flexible, accurate and versatile performance, currently, the industrial baseline for beamforming in 5G antennas are mostly based on analog architectures that can generate a single beam at a time [2].…”

“…It is worth to mention here that according to the beamwidth (and depending on the cell size), it might be necessary to adjust the input power to satisfy the demanding 5G mm-wave link budget requirements. Additionally, in 5G, it is desired, for each beam with a different resolution, to have a wide-angle scanning capability with low side lobe levels (SLLs) in order to ensure a high Quality-of-Service (QoS) in the statistical sense [1].…”