Performance of STBC PPM-TH UWB Systems with Double Binary Turbo Code in Multi-user Environments

The performance of space time block code (STBC) pulse position modulation-time hopping (PPM-TH) ultra-wide band (UWB) systems with double binary turbo coding is analyzed and simulated in multi-user environments. The channel model is considered as a modified Saleh and Valenzuela (SV) model which was suggested as a UWB indoor channel model by the IEEE 802.15.SG3a in July 2003. In order to apply the STBC scheme to the UWB system considered in this paper, the Alamouti algorithm for real-valued signals is employed because UWB signals with the pulse modulation have the type of real signal constellation. The system performance is evaluated in terms of bit error probability. From the simulation results, it is demonstrated that the double binary turbo coding technique offers considerable coding gain with reasonable encoding and decoding complexity. Also, it is demonstrated that the performance of the STBC-UWB system can be substantially improved by increasing the number of iterations in the decoding process for a fixed code rate. Also, it is confirmed that the double binary turbo coding and STBC schemes are very effective in increasing the number of simultaneous users for a given bit error probability requirement. The results of this paper can be applied to implement the down-link of the PPM-TH UWB system.