On timing constraints and OFDM parameter design for cooperating basestations

It is well known that symbol timing offsets larger than the cyclic prefix between transmitter and receiver stations destroy the orthogonality among OFDM subcarriers inducing interblock interference by coupling subsequent OFDM symbols. In conjunction with MIMO transmission over frequency selective channels, this effect on top of multi-user interference strongly degrades performance. In this paper we analyze the timing constraints in cellular MIMO OFDM networks that necessarily occur due to time-of-arrival differences of signals from different locations. We investigate a simple hexagonal model, where three users transmit their data on the same time-frequency resource to three cooperating base stations. Based on a detailed analytical derivation of the transmission model we present results for the post detection SINR in systems with symmetric and uniform user distribution within one cooperative cell.