Research On Channel Models Based On Ultra-wide Bandwidth Wireless Communication In Indoor Environment

Ultra-wideband (UWB) communications arisen in the last two decades which has been widely studied is wireless communications technology, which uses pulses to transmit information directly, without carrier, so the transceiver is simple. UWB communications, whose bandwidth is several GHz and transfer rates can reach500Mbps or even higher, has the advantage of high transmission speed, great system storage. Information power of sent pulses is small, almost below the white noise, the existing spectrum can be shared, so UWB wireless communications technology can ease the increasing tension of spectrum resources. Because its transmission power is small, the effective transmission distance is generally within10meters, so UWB wireless communications technology was mainly applied for indoor short-range and high-speed data transmission, which has broad applications in the next room multimedia communications in future.Ultra-wide band (UWB) communication has been the subject of extensive research in recent years due to its unique capabilities and potential applications, particularly in short-range multiple access wireless communications. However, many important aspects of UWB-based communication systems have not yet been thoroughly investigated. The propagation of UWB signals in indoor environments is the single most important issue with significant impacts on the future direction, scope, and generally the extent of the success of UWB technology. The objective of this dissertation is to obtain a more thorough and comprehensive understanding of the potentials of UWB technology by characterizing the UWB communication channels. Channel characterization refers to extracting the channel parameters from measured data. The extracted parameters are used to quantify the effect of the channel on communication UWB systems using this channel as signal transmission medium. Data are measured in different ways using a variety of time-domain and frequency-domain techniques. The experimental setups used in channel characterization effort also include pulse generators and antennas as integral parts of the channel, since the pulse shape and antenna characteristics have significant impact on channel parameters. This article focuses on the research of ultra-wideband indoor wireless communication channel model.Firstly, this paper introduces the research background and the significance and main application of UWB communication, as well as the research status at home and abroad. Secondly, UWB indoor channel modeling method was described, which are time domain and frequency domain modeling methods, and the advantages and disadvantages of the two modeling methods were analyzed and compared. The main factors of channel measurements, the pulse waveform, antenna and building materials, were qualitative analyzed. Studying the existing channel models, mainly for IEEE802.15.3a channel model simulation, some limitations are improved. Thirdly, the space geometry statistical channel model is proposed based on a single reflection geometric method, and the joint probability density distribution of the model, the arrival time distribution and the arrival angle distribution were derived. Proposed the hollow-disc model for outdoor and indoor environment modeling needs, derived spatiotemporal distribution, angle of arrival distribution and the arrival time distribution of the model, and gives the corresponding simulation figure. Finally, the summarization of the thesis is given, And the future study direction is also pointed out.The research contents of this paper are as follows:First, described channel modeling methods:time domain and frequency domain modeling method, and its measurement principle, composition, procedures and data processing were given, the advantages and disadvantages of two measurement methods were analyzed and compared. Qualitative analysis of signal propagation in the process of distortion of the main factors:pulse waveform, the antenna characteristics and building materials on channel measurement effect.Second, studied IEEE802.15.3a channel model and simulated four channel models under different environmental conditions, namely:CM1, LOS,0-4m. CM2, NLOS,0-4m. CM3, NLOS,4-10m. CM4, NLOS,4-10m (which was in under extreme environments). The model of some defects were improved, the concrete is as follows. Based on the signal propagation characteristics, the number of clusters was proposed as two for CM1, LOS,0-4m environment, the new model of defined cluster number model was simulated, and the experimental data was compared with the University of Southern California, it found that the new modified model of defined cluster number is better than the original model. Based on the property of clusters arrival, modified the channel model parameters for CM2, NLOS,0-4m environment, simulation results show that the channel model which modified parameters can reflect the characteristics of signal clusters arrival better, it is more fitting of the measured data better than the original model.Third, studied the space geometry statistical channel model, which is based on the geometrical structure of the temporal and spatial distribution of method, the paper derives the general geometric model of the temporal and spatial distribution of function. Put forward hollow-disc model for indoor and outdoor environment modeling of the channel, a simple method is used to derive the spatiotemporal distribution, arrival angle distribution and arrival time distribution, and the choice of different hollow ratio and environmental parameters are given the corresponding simulation figure.