Node Density and Range Improvement in Cooperative Networks using Randomized Space-Time Block Coding with Time Synchronization Errors

Cooperative communication in energy-constrained networks is a topic of emerging interest in recent years especially for sensor network applications. We consider cooperative transmission from a cluster of nodes to a remote receiver. The transmission protocol used is randomized orthogonal space-time block coding, which allows each node to randomly transmit one column of a given orthogonal space-time code matrix. Previous work on the topic has shown that the scheme can achieve maximum possible diversity order for a given SNR as the number of cooperating nodes increases. In this paper we examine the range extension achievable under realistic conditions accounting for time synchronization errors and use of pulse shaping filters. We show that the scaling of range as the number of nodes increase with timing error is not linear. It reaches a limit beyond which range improvement is not significant