Research On Code Domain Transmitted-Reference Ultra-wideband Communication Transmission And Anti-interference Technologies

The Ultra-wideband (UWB) wireless communication system has many advantages such as very low interception and detection probability, excellent anti-interference and material penetration abilities, good performance of system coexistence, high rate data transmission suitability, high precision ranging, and so on, thus making the UWB technology qualified for broad application in military and civil wireless communication. At present, UWB communication technology is mainly used in short distance and high data rate transmission. Meanwhile, there is a strong demand for extending the transmission distance of UWB communication technology in many domains such as national security, antiterrorism and social stabilization, traffic and industrial control, and so on.The impulse radio UWB (IR-UWB) system based on the transmitted reference structure can avoid complicated channel estimation, effectively reduce the demand for synchronization accuracy , collect the energy of multipath, and facilitate miniaturization and low power-consuming system design. Accordingly, IR-UWB system based on the transmitted reference structure becomes an important research direction. Transmitted reference IR-UWB system has three realization structures: time domain, frequency domain, and code domain.Based on the code domain transmitted reference IR-UWB system (the author is one of the designers), the study is followed up in depth in this paper with emphasis on extended distance UWB communication. The main content and innovation are as follows:1. From the point of improving the bit error rate (BER) performance of system, this paper proposes a modified receiver structure of code domain transmitted reference IR-UWB system. The structure model of the receiver is given, and in additive white Gaussian noise (AWGN) and multipath fading (MP) channels, the BER performance expressions are deduced in detail, respectively. The BER performance is also simulated. In addition, this paper studies the synchronization acquisition performance of the modified receiver, and in AWGN and MP channels, the parameter expressions of synchronization acquisition are deduced in detail, respectively. The synchronization acquisition performance is also simulated. The research results indicate that by appropriately increasing the structural complexity of receiver, the modified receiver not only keeps the inherent advantages of the original code domain transmitted reference IR-UWB system receiver, but also achieves improved performance through the selection of optimal integral interval.2. From the point of improving the system information transmission rate, a multiple parallel transmission method of code domain transmitted reference IR-UWB system is proposed. This paper gives the structure model, and the BER performance expressions in AWGN and MP channels are also deduced in detail, respectively. The selection method of orthogonal code is also given. In addition, the performance of the proposed structure is simulated. The research results indicate that by energy multiplexing of reference signal, the multiple parallel transmission structure can not only accommodate to higher transmission rate, but also outperform the original code domain transmitted reference IR-UWB system in error performance for each data signal with middle and low signal niose ratio.3. Aiming at the application requirement of multi users, a multiple access transmission scheme of code domain transmitted reference IR-UWB system is proposed. This paper proposes the structure model, and based on a Gaussian assumption for the multiple access interference, the BER performance expressions in AWGN and MP channels are also derived in detail, respectively. In addition, the performance of the proposed scheme is simulated. The research results indicate that by introducing a pseudo-random time hopping code to the code domain transmitted reference structure to the code domain transmitted reference structure, the scheme can effectively control the influence of multiple access interference. And the system realization complexity is low.4. From the point of improving the system anti-interference performance, an interference suppression method of code domain transmitted reference Chirp-UWB system is proposed. This paper studies the anti-interference performance of the code domain transmitted reference Chirp UWB system. The output signal and noise component expressions of single frequency and narrowband interference of system receiver is deduced, and the anti-interference performance of system is simulated. Furthermore, by combining with the structure of the active spectrum compression, a narrowband interference suppression method based on the fractional Fourier transform is proposed, and its validity is verified through simulation. The research results indicate that the narrowband interference method proposed can effectively suppress the multi random narrowband interference, and is thus of practical value.The extended distance UWB communication transmission and interference suppression methods proposed in this paper has been well used in the relevant projects as a basic technology solution.