A Compact Preamble Design for Synchronization in Distributed MIMO OFDM Systems

In distributed multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, signals arrive at the receiver on different timing and are characterized by distinct carrier frequency offsets (CFOs), which makes synchronization rather challenging than that associated with centralized MIMO systems. Current solutions to this problem are mainly based on special preamble designs, where different training sequences are cascaded and then separately used to assist timing synchronization and CFO estimation. Such preamble designs not only increase system overhead but also burden the receivers with independent algorithms for timing synchronization and CFO estimation. In this paper, we propose a low-overhead (compact) preamble having the same length as one OFDM symbol, along with a unified algorithm for both timing synchronization and CFO estimation. Furthermore, the CFO estimation range can be flexibly extended to cope with larger CFOs in the proposed approach. Under the same training overhead and power consumption, simulation results indicate that the proposed approach outperforms a timing synchronization scheme that based on unequal period synchronization patterns.