Study On A Novel Modulation Scheme In Ultra-Wideband(UWB) Communication System

The technical background, present research status, characteristics, basic theory, propagation channel, key techniques and application foreground of ultra-wideband (UWB) communication are introduced in this paper. We analyze the conventional binary modulation schemes and multiple modulation schemes based on analyzing and comparing the characteristics of UWB signals. Then a time-hopping(TH) MN-ary biorthogonal pulse amplitude position modulation(MN BPAPM) scheme with higher transmitting speed, better anti-multipath performance, simpler structure is presented.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 improve information transmitting rate, the multiple modulation schemes are emerged including TH M-ary pulse amplitude modulation(TH M-PAM) and TH M-ary pulse position modulation(TH M-PPM). Based on analyzing the two multiple modulation schemes, the expressions of symbol error rate(SER) are presented and the system performances are compared.Focusing on the problem that the low transmitting efficiency and the high bit error rate of the above modulation techniques in UWB communication systems, a TH MN BPAPM scheme was proposed to improve the system performance. Firstly, the signal expression and system construction model are presented, then the closed-form expressions of symbol error rate(SER) and channel capacity and their simple expressions are provided over an additive white Gaussian noise(AWGN) channel. The results show that the system has lower SER when MN is larger. At the same time, when MN is a constant, the smaller M leads to lower SER. Compared to the UWB communication system of time-hopping MN-ary orthogonal PPM(TH MN OPPM), when MN is the same and M equals to 2, TH MN BPAPM scheme has lower SER and the complexity of the system is decreased by 50%. In addition, from the channel capacity analysis of TH MN BPAPM UWB communication system, we can conclude that the system channel capacity can reach to the limit log 2MN when the system accesses fewer users or the input signal-noise-ratio(SNR) is larger.