An Anti-Interference Coding in UWB-OFDM Communications

An anti-interference orthogonal coding is introduced based on Hadamard code and Orthogonal Frequency-Division Multiplexing (OFDM), in which all sub-channels of Ultra-WideBand (UWB) system are divided into M sub-bands and the power of the every transmitted symbol spreads over each of the sub-bands rather than one sub-band. The complete mathematical analytical relation between encoding and decoding is present and the robustness of the system to interference is examined. When some sub-channels are affected by interference or jamming, the system could regenerate the symbol from others. Simulation results show that the Anti-Interference UWB-OFDM (AI-OFDM) system has evident advantages over conventional UWB-OFDM systems as well as the Interference Suppressing UWB-OFDM (IS-OFDM) in Bit Error Rate (BER) thanks to its robustness to interference. In the case of bad interference, the AI-OFDM system could work up to snuff without any anti-interference step, but the conventional UWB-OFDM system couldn't. Compared with the IS-OFDM system, the AI-OFDM system improves the performance about 5 dB in Signal-to-Interference Ratio (SIR) and the order of 1～2 in BER.