In this paper, we present a broadband wireless communication system. This system is designed using updated techniques. These techniques consist of space-time coding, turbo codes, and OFDM. Moreover, a differential detection scheme is also included such that neither channel estimation nor channel equalization is required. Soft output of the detection is derived for turbo decoding. At a throughput of 2 bit per symbol, BER of the system can reach 10/sup -5/ while E/sub b//N/sub 0/ is less than 10.5 dB.