User slot design and performance analysis for burst mode communications with fading and frequency uncertainty

High performance and reasonable complexity have made the pilot symbol assisted modulations (PSAM) of practical interest in mobile communications. However, no previous work has investigated PSAM in burst mode operation which is commonly encountered in multiple access schemes (time division or slow frequency hopped system). The paper examines the burst structure design problem in a frequency flat fading environment. The explicit relationship between error performance and the design parameters including pilot allocation, frequency offset, Doppler spread, and modulation scheme is explored. Periodic pilot insertion commonly used for continuous transmission produces degraded performance in burst mode operation. A new unequal spacing pilot insertion burst architecture is proposed to achieve better error performance. The explicit bit error probability results of the present work can be used to evaluate the potential performance improvement of a frequency offset estimator and a Doppler spread estimator.