Burst coherent demodulation with combined symbol timing, frequency offset estimation, and diversity selection

A low-overhead burst coherent demodulation method that jointly estimates symbol timing and carrier frequency offset and then performs diversity selection is studied. It coherently demodulates individual bursts of TDMA (time division multiple access) symbols by operating solely on random data within the burst without requiring training sequences. Its performance is robust against frequency offset between transmitter and receiver, thereby eliminating the need for a highly stable frequency reference. The performance of this demodulation method in a fading channel can be further improved by using a diversity selection technique based on a quality measure derived as part of the joint timing/frequency offset estimation process. Simulations and experiments have confirmed that two-branch diversity using this method can provide reliable speech communication using TDMA with a transmission rate of 450 kb/s for a portable radio channel with an RMS delay spread of 555 ns or less