Switched beam selection techniques for 60GHz communications

Abstract

In recent years, millimeter-wave 60GHz band technology has gained special interest because it supports ultra high data rates. For reliable communication at 60GHz band, beamforming techniques are very important, especially in the non-line-of-sight (NLOS) environment. Switched beamforming techniques have advantage of simple implementation. However, since the directions to which the beam is steered are limited, beam selection techniques are required to select the optimal beam out of the limited number of beams and minimize performance degradation. We present research activities related to the switched beam selection techniques. At first, we implement a digital system to control a switched beamformer. We use the received signal-strength indicator (RSSI) to control phase shifters in the beamformer block. We design a simple algorithm and implement a hardware module to operate the algorithm. Measurement results show that the implemented system would be an example to solve the link margin and recovery problems for 60GHz radio systems in NLOS scenarios. Secondly, we propose switched beam selection methods for single carrier frequency domain equalization (SC-FDE) which is a transmission technique at 60GHz band. We define and use the effective average SNR and the minimum SNR as the beam selection criteria in both the point-to-point and multi-point-to-point wireless link models. Simulation results show that proposed beam selection methods achieve the diversity gain and improve the bit error rate (BER) performance, indicating that selection methods enhance the accuracy of beam selection.