Equalization for Outdoor mmW Deployments

Millimeter wave (mmW) frequencies are considered to be indispensable for next generation wireless systems, both cellular and Wi-Fi, primarily due to the large amounts of spectrum available in these bands. However, the higher frequency-dependent path loss at these frequencies needs to be overcome by the use of high-gain directional antenna arrays at both transmitter and receiver. Due to the complexity and peak to average power ratio (PAPR) requirements of OFDM, single-carrier is being considered for the physical layer, which brings up the question of appropriate equalization. In this paper we present a simulation study of equalization structures specifically for a mmW outdoor system, using realistic ray tracing simulation software to generate multipath channels depending on the transmit and receive antenna beam-widths. We then compare decision feedback equalization (DFE) with linear equalization (LE) for these channels and show that in an urban multipath environment the use of DFEs can offer significant gains even with very narrow antenna beams, while the gains are smaller in a suburban environment with less multipath.