基于正交互补码的Chirp超宽带系统的研究与优化设计

Ultra wideband (UWB) technology is mainly used in wireless short-range high speed communication and it has been considered as the PHY standard and the main transmission technology of future wireless personal area network (WPAN). The basic implementation form of UWB is impulse radio. Chirp UWB system is based on this form, it substitutes the frequency-modulated signal for the traditional narrow impulse with the help of linear frequency modulation and spread spectrum technologies and has many advantages, such as flexible pulse design and excellent interference suppression, etc. For the suppression of different narrowband interference (NBI) of UWB system, it is a key issue to design the flexible Chirp UWB pulse. Considering the real work environment of UWB system, it is also very important to obtain the excellent system performance with the improved abilities for the resistance of multiple access interference (MAI) and multipath interference (MPI). The latest proposed orthogonal complementary code (OCC) has inherent characteristics to resolve the above issues. In this project, we will provide the comprehensive research and design of OCC Chirp UWB system with the consideration of the main kinds of interference, such as NBI, MAI and MPI. Through the analysis and design of the novel non-linear Chirp UWB pulse and the OCC, we will present the optimal system design scheme and the criterion to improve the system reliability, efficiency and also the spectrum sharing ability. This research has great importance to enhance and boost both the theoretical research and also the application of UWB system in WPAN.

超宽带技术主要用于短距离高速无线通信，被公认为未来无线个域网的物理层标准和主流传输技术，其主要实现形式即冲激无线电。Chirp 超宽带系统即基于此方式，它通过采用线性调、扩频技术，用调频信号替代传统窄脉冲，具有设计灵活、抗干扰能力强等优点。而采用非线性方案设计能灵活抑制多窄带干扰的Chirp超宽带脉冲是一个关键问题。此外考虑超宽带系统的实际工作环境，在保证系统性能的同时提高超宽带系统的抗多址、多径等干扰的能力，也是超宽带系统设计的核心和关键。新近提出的正交互补码技术可有效解决上述问题。本课题将从互补码Chirp 超宽带系统的整体设计出发，考虑实际存在的各主要干扰，如窄带干扰、多址和多径干扰，通过设计新型非线性Chirp 脉冲和正交互补码，创新性地给出超宽带系统的优化设计方案及准则，提高其在实际使用环境下的可靠性和有效性，改善频谱共享，这对其在无线个域网中的理论研究和实际应用将具有重要意义。

本项目的主要研究目标即给出基于正交互补码的Chirp超宽带系统设计原则及准确系统理论性能分析，实现超宽带通信环境下多窄带干扰、多用户干扰及多径干扰的有效消除和抑制。我们首先从超宽带系统波形设计入手，基于Chirp函数提出了具有抗多窄带干扰能力的Chirp超宽带脉冲的设计准则，并设计给出了改进的线性及非线性asinh Chirp、atan Chirp以及SQRT Chirp超宽带波形，实现了低复杂度的多窄带干扰灵活抑制。在此基础上，基于正交互补码的设计思想，进一步设计和分析了基于互补码的Chirp超宽带系统设计，根据多经信道特性设计对应的正交互补码参数，从而利用其相关特性实现多用户干扰和多径干扰的有效抑制。同时，根据正交互补码Chirp超宽带系统设计特点，给出了两种实现形式，即单带及多带正交互补码Chirp超宽带系统设计方案。上述研究提高了超宽带系统在实际使用环境下的可靠性和有效性，有效提高了超宽带系统的抗干扰能力，改善了其频谱共享，这对超宽带技术在无线个域网中的理论研究和实际应用将具有重要意义。