| Compared to wire line networks,wireless networks have higher removability,while they face the difficulty of bad wireless communication environment and limited spectrum resource. At the same time,people require more for wireless communication systems,expecting higher data rate,lower cost,and less energy.Under this background,Ultra-Wideband(UWB) technology attracts much attention over the world.UWB is an important technology for indoor high rate wireless communications and now it is looked as one of the key technologies for the next generation wireless communication systems.The first part of this thesis includes an introduction of research background,a brief introduction of UWB Technology.Secondly,the thesis decrypts the basic principle,the structure,and the technology of interference resistance of OFDM,and the characteristics of the UWB channel.Then the UWB system based on OFDM modulation and the UWB system based on the combination of OFDM and CDMA technologies were analyzed,iterative receivers applies the Soft Symbol Based(SSB)-MMSE(Minimum Mean Squared Error)and Soft Chip Based(SCB)-MMSE algorithms were presented.The receivers exchange Extrinsic Information of the coded bit.They make full use of the advantages of MC-CDMA and FHMA and reduce the effect of the channel noise,multi-path and narrowband interference on the system.Simulation results show that the iterative receivers have better performance in bit error rate performance than the traditional MB-OFDM system and SS-MC-MA system on the channels proposed by IEEE 802.15.3a TG. |
