Research On The MB-OFDM UWB System With Space-Time-Frequency Coding

Recently, UWB (Ultra-Wide Band) communications attracts intensive attention, because it is a potential candidate for short-range communications with very high data rate, very low power consumption and emission. A UWB communication is MB-OFDM (Multi-Band Orthogonal Frequency Division Multiplexing) UWB, being taken out recently years. In this chapter, we discuss the combination between the MB-OFDM UWB, MIMO(Multiple-Input and Multiple-Output), and STCs, which can improve the performance of the conventional multimedia communications between portable devices with very high data rates, improved communications quality, and low cost.In a MIMO-OFDM system, the signal is transmitted with subcarriers in different frequent, so there is a frequent diversity itself. So the STCs implementing in MIMO-OFDM system is named STFCs (Space-Time-Frequency Codes). A MB-OFDM UWB system using STFCs is called STFC MB-OFDM UWB system.This paper uses the great similarity between the STFC MB-OFDM UWB systems and CO STBC (Complex Orthogonal Space-Time Block Code) MIMO systems to quantify the PEP (pairwise error probability) of the proposed system and derive the general decoding method for the implemented STFCs. The maximum achievable diversity order is found to be the product of the number of transmit antennas, the number of receive antennas, and the FFT size. The paper also designs a method of diversity according to the standard of MB-OFDM UWB system. This method can increase the diversity gain, and then improve the PEP performance. In the last chapter, we consider the co-channel interference of different device, for the STFC MB-OFDM UWB system used in short-range communications. So we derive the beamforming, which can be used to relieve the CCI with angular diversity.