A simple OFDM diversity receiver based on antenna combining

This work proposes a simple OFDM (orthogonal frequency division multiplexing) diversity receiver based on antenna combining. The proposed scheme employs an electromagnetic-coupled array antenna whose elements are terminated with the variable capacitor except for a main element, which is connected to the conventional OFDM receiver. The reactance values of the variable capacitors are controlled in order to maximize the received signal strength. However, the accurate measurement of the signal strength is a difficult task because of the OFDM does not have constant envelope. In order to solve this problem, we propose an antenna-combining diversity scheme which controls the reactance-values according to the packet errors. The packet error is easily detected by making use of CRC (cyclic redundancy check) code. Computer simulation results show that the proposed scheme can not only remove the signal strength measurement component but also improve the packet error rate performance with comparison to conventional signal-strength based antenna combining.