Physical layer coexistence: WLAN/radar case study

Abstract

Spectrum sharing of 802.11 wireless local area network (WLAN) and radars operating in co-/adjacent channel scenarios (notably 5 GHz) is a problem of considerable importance that requires new innovations. The spectrum sharing explored in this chapter is based on unilateral action by Wi-Fi networks to prevent unacceptable interference to incumbent radar and also mitigating the interference from radar to Wi-Fi. Specifically, the ability of a single Wi-Fi network inside the exclusion region is to speedily detect radar operation and to subsequently switch to a clear channel as a means of protecting them. The approach is relied on the opportunistic use of naturally occurring random quiet/idle periods in a Wi-Fi network employing distributed coordination function (DCF) to detect the presence of a radar using energy detection. Moreover, the Wi-Fi systems outside the exclusion region are modified to mitigate the interference from a pulsed search radar such that the WLAN continues to operate with no noticeable performance degradation. The radar pulse detection is required to mitigate the radar interference.