Working Out The Key Technologies Of UWB On Time-Hopping Modulation, EMC And Positioning Algorithm

For realizing the service target of seamless coverage in a global range and providing high-data rate multimedia communication, the communication network should be an integrated network including several communication technologies which at lest consists of wireless and cable. Such being the case, ultra-wide band (UWB) has become a favourite technology for wireless communication due to its good characteristics such as ultra wide bandwidth, low power, frequency reusing and so on.UWB owns many advantages such as high transmission data-rate, high reliable transmission, high time and spatial resolution, low power, low cost, miniaturization and so on, which make UWB very suitable for short-range wireless communication, high precision ranging and positioning or detection application. The study topics for UWB include signal waveform design, antenna design, channel model research, IC design, network buildup, new modulation technology, EMC and so on.The work of this paper aims at developing UWB at the aspects of communication capacity, high accuracy ranging, and the co-existence ability between UWB and other narrow band wireless systems. All the work is based on the essential UWB characteristics of wide bandwidth and low power requirement.The contents of this paper include:1．A new time-hopping UWB modulation method called multi-pulse position modulation (MPPM) constructed by constant weight code (CWC) is proposed. And the performance of MPPM is analyzed in several aspects such as channel capacity, probability of symbol error, link budget margin, power efficiency, bandwidth efficiency and receiver complexity. Theory analysis and numerical results show that L-ary MPPM can perform better than L-ary pulse position modulation (PPM) and L-ary pulse amplitude modulation (PAM) do under some conditions. The proposed MPPM can be a good candidate for UWB short-range and high data-rate wireless communication application.2．A novel time-hopping UWB modulation scheme called ambipolarmulti-pulse position modulation (AMPPM) is proposed. The AMPPM signal is constructed by extending constant weight code (ECWC) and analyzed based on the existing biorthogonal pulse position modulation (BPPM) and MPPM. The error probability, receiver complexity, channel capacity, data-rate, bandwidth efficiency, power efficiency and maximum reliable transmission distance of AMPPM are derived over an additive white Gaussian noise (AWGN) channel. Theory analysis and simulation results show that AMPPM can get a better performance character than PPM, PAM, BPPM and MPPM do under the same condition. AMPPM could also be a good candidate for UWB high-data rate wireless application.3．Since the narrowband wireless systems could be disturbed by UWB devices, a 3D integral model is introduced to analyze the impact of UWB cumulative interference on the narrowband wireless systems, and the proposed model is divided into two situations which are LOS and LOS-NLOS mixture. The proposed analysis model can evaluate the UWB interference effect on victim receivers efficiently and deliver numerical evaluation results of both the anti-UWB interference ability of different wireless systems and the protection ability of different UWB emission masks. The analysis method and model can be a useful theoretical reference for the study on UWB devices layout in modern buildings and the UWB emission power control.4．A new UWB ranging algorithm based on a kind of special sequencecalled almost perfect autocorrelation (APA) sequence is introduced, and some theory and simulation results are given under AWGN channel and IEEE recommended UWB channel model respectively. The comparison results of ranging accuracy between the ranging systems with and without APA sequence show that the APA sequence can get higher ranging accuracy than the common sequence under the same condition, and increasing the length of the APA sequences can lead to better ranging precision but need more time and energy loss. So the APA sequence is a good candidate for UWB ranging system and the length of APA ranging sequence should be selected according to the particular application.5．Based on the UWB ranging technology, a plane vehicle positioning system is designed for the intelligent transport system which only needs two reference nodes in an ideal environment. And for improving the positioning accuracy of the proposed system under a non-ideal condition, another three algorithms based on solution-averaging, distance-averaging and angle of arrival (AOA) ranging plane amending are also introduced. The theory analysis and simulation results show that the proposed positioning system can perform vehicle positioning task and get a high positioning precision assisted by the modified algorithms.