LO Synchronization Scheme via Full-Duplex Transceiver for Distributed Beamforming in Wireless Ad hoc Networks

In this paper, we demonstrate a prototype system for path independent local oscillator (LO) synchronization of a distributed beamformer in wireless ad hoc networks. The system contains a low power full duplex (FD) transceiver IC, a RF phase interpolator IC, and a CDMA encoder/decoder to realize a conjugate loop and synchronize the LO’s of two RF nodes. Both ICs were fabricated in 180nm CMOS technology. The FD transceiver IC consumes 69mW at 700MHz and the RF phase interpolator IC consumes 75mW at 1.4GHz. Using the low power ICs, we demonstrate a simple, lightweight, and robust methodology to synchronize two LO’s with an average phase precision of 2.1° and 94% maximum beamforming gain using RF only transmissions via a single antenna per node.