摘要
本文介绍了超宽带(UWB)通信的技术背景与研究现状、特点、基本原理、传播信道、关键技术和应用前景。首先介绍了UWB通信中所使用的高斯脉冲及其各阶导函数,随后对各种传统二进制调制方式包括跳时-脉冲位置调制(TH-PPM)、跳时-二进制相移键控(TH-BPSK)和直扩-二进制相移键控(DS-BPSK)UWB通信系统的性能进行了分析。为了提高传输信息的速率,简化计算复杂度,分别提出了两种新的方法:
(1)推导了在AWGN信道和多径条件下,基于重叠和正交脉冲信号的TH-BPPMUWB系统的误码率公式。结果表明在AWGN信道条件下,基于重叠脉冲信号的TH-BPPM系统性能优于基于正交脉冲信号的,但如果重叠脉冲信号没有最优化设计,那么其系统性能将会很差。在多径条件下的正交TH-BPPM的系统性能,优于AWGN信道条件下的系统性能。
(2)提出了一种直扩序列与跳时码混合的超宽带系统(DS/TH-UWB),并针对该系统提出了一种简单可行的误码率分析法,并分别仿真了在用户比特能量相等和不等时的情况下,系统的误码率曲线,结果证明:主要被用于DS-CDMA系统的一种基于SIGA的简单而可行的误码率分析法,同样也适用于DS/TH-UWB多址系统。
The technical background, present research status, characteristics, basic theory, propagation channel, key techniques and application foreground of ultra-wideband communication are introduced in this paper. Firstly, the Gaussian pulse and its various differential functions in UWB communication system are introduced. Later, we analyze performance of various conventional binary modulation UWB communication system including TH pulse position modulation(TH-PPM),TH binary phase shift keying(TH-BPSK)and direct-sequence binary phase shift keying (DS-BPSK). In order to increase the rate of transmission, simplifying the complexity, the paper proposes two new ways:
(1)Deduction the formula of the TH-BPPM UWB system bit error rate on the AWGN and multi-path channel conditions, based on the overlap and orthogonal pulse. The results show that the AWGN channel conditions, based on the overlapped of the pulse signal TH-BPPM have a superior system performance to based on orthogonal TH-BPPM pulse signal. But it can be severely worse if the signals are not well designed. Conditions on multi-path of the orthogonal TH-BPPM system performance, superior AWGN channel under the conditions of system performance.
(2)A hybrid direct-sequence time-hopping (DS/TH) impulse radio IR UWB multiple access system is proposed and a simple error analysis is presented for the system. The error analysis facilitates to obtain simple-to-evaluate and accurate error probabilities based on Holtzman's simplified improved Gaussian approximation (S1GA), a method that has previously mainly been used in DS-CDMA. The simulated results show that the method can also be used effectively for IR UWB multiple access systems.
引文
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