【作者】 曾志斌；

【导师】 庄奕琪；

【作者基本信息】 西安电子科技大学 ， 集成电路系统设计， 2010， 博士

【摘要】 随着通信集成电路的快速发展和SOC技术的不断推广,通信设备制造趋向于芯片化设计,从以前的分立式元件向SOC发展。扩频通信在通信领域占有重要的地位,芯片化设计中较多采用直接序列扩频技术,而作为扩频通信重要的技术分支M元扩频它的芯片化却少有实现。论文在深入研究M元扩频基本理论的基础上,对M元通信芯片化设计展开相关工作,提出适合芯片化的M元扩频改进算法,并利用SOC技术进行芯片化设计工作。论文的主要贡献如下:1针对采用同步码实现同步的M元扩频方案,提出两种改进方案。它们通过将扩频码的码相位和码极性相结合而实现。方案一用BPSK调制直扩替代同相支路上的同步码,在正交支路上采用基于CPSK(code phase shift keying,码相位循环移位)调制的M元扩频。这里同相支路选用的扩频码是用于正交信道扩频码源码的倒序序列。相对于采用同步码实现同步的M元扩频方案,该方案可以增加1比特信息的传输量;方案二进一步提高扩频码的资源利用率。它将所有的扩频码改进成均由一条扩频码通过循环移位提供,但对同相支路与正交支路采用的扩频码的码相位进行码相位约束以确保可实现自我同步。采用以上方案还具有易于系统集成的特点。2为了在保持较高的频带利用率的条件下提高M元扩频的码资源利用率,给出在同相支路上采用传统的M元双正交扩频,在正交支路上采用基于CPSK调制技术的M元扩频的方案。该方案所需扩频码码资源是传统M元扩频的条数只需约四分之一。为了进一步提高扩频码利用率,在此基础上提出采用同步帧结构的正交两路CPSK调制M元扩频的改进方案。它的同步码是通过在两支路同时采用特定相位的扩频码进行传输而实现。它的优点是同步码易于识别。以上两方案降低系统设计复杂度,易于系统芯片化设计。3为了提高M元扩频系统在衰落信道下的性能,给出在空时编码后采用M元扩频的方案。在此基础上提出将空时编码用于M元扩频码片的方案。后者在一个码元时间内就能完成信号处理,具有处理时延小的特点。同时该方案在时间选择性快衰落情况下,它可以获得更多的时间分集增益,从而提升系统的性能。4针对时间选择性快衰落条件下难以有效的估计信道信息,分析在扩频码码片上采用差分空时编码的方案。该方案具有较强的抗快衰落性能并且当信道相干时间小于一个符号周期时,该方案能获得更多的时间分集增益,系统性能得到改善。在此基础上分析在M元扩频码片上采用空时编码方案的性能。以上方案可适应大的晶振频偏影响,易于芯片化设计,适于低成本,小体积的便携式产品设计。5对M元扩频系统核心模块进行功能划分,给出芯片化实现算法,利用EDA工具完成IP软核设计和验证,并完成数字化版图设计。更多还原

【Abstract】 With the rapid development of communications IC and continious promotion of SOC technology, communications equipment manufacturers tend to realize by IC, from the previous discrete components to the SOC development. Spread Spectrum Communication plays an important role in the communications field. IC design of Spread Spectrum Communication has mainly applied to direct sequence spread spectrum. The M-ary spread spectrum is one most important component in spread spectrum communication system while its IC chip achieves little. The basic theory of M-ary spread spectrum is studied deeply in the paper, which is useful in.the realization of M-ary spread spectrum IC design. Some improved algolithms are given, which suit IC design. And SOC technology is adopted in realization of M-ary spread spectrum chip. The main contribution of paper is as follows:Firstly, two improved scheme combining code polarity of spreading code with code phase of spreading code are proposed for M-ary spread spectrum system which needs synchronization code. Scheme 1 adopts BPSK modulation based on polarity modulation of PN in in-phase branch, and CPSK(code phase shift keying) modulation based on phase modulation of PN code in orthogonal branch. The scheme is easy to realize because all spread spectrum codes comes from one SS code and its reverse order sequence. Compared to the M-ary spread spectrum system which need synchronization code, the new scheme can add a bit of information transmission capacity. Scheme II reduces the resource of spreading code further. In the scheme, the code set of SS codes comes from one SS code by cyclic shifting with the limit of phase area, which is easy for IC design.Secondly, in order to improve the utilization of spreading code resource under the conditions of high bandwidth efficiency, a scheme is proposed which adopts M-ary biorthogonal spread spectrum modulation in in-phase branch, and CPSK spread spectrum modulation in orthogonal branch. The system has the advantages which can achieve synchronization accurately and fleetly by itself, but rather offer additional synchronization resource. The scheme maintains a comparable performance as the M-ary spread spectrum but needs only about quarter of spread spectrum codes of M-ary spread spectrum system, which saves source of spread spectrum codes effectively. And more, an improved scheme is proposed to solve the limitation that conventional spread sptrum communication suffers from spreading code sources. The scheme proposed double code phase shift keying spread spectrum communication system which adopts structure of synchronization frame. The all SS codes come from one SS code by cyclic shifting. Synchronization is achieved by transmit the synchronization code at both orthogonal channels at the same time which is easy to distinguish. Both of the schemes has low complexity and is easy for IC design.Thirdly, in order to improve the bit error ratio(BER) performance of M-ary spread spectrum in fading channel. We propose a scheme which adopts space-time coding before M-ary spread spectrum. And more, we propose applies space time block coding to chips of spread spectrum code which has shorter decoding delay because both detection and decoding can be completely performed within one symbol period. And under the time selective channel, the scheme can get more time diversity, which can improve BER performance.Fourthly, for time selective fast fading condition which is difficult to estimation channel state information, we propose a scheme in which difference space time coding is applied to chips of direct sequence spread spectrum. The scheme is robustness in the presence of oscillator frequency offsets and fast time-selective fading channels. Further more, we apply difference space time coding to chips of M-ary spread spectrum. Compared to the scheme that difference space time coding is applied to chips of direct sequence spread spectrum, the scheme can improve the system performance and information bit rate greatly with the increase of the diversity order. Both the schemes are simple for IC design and acceptable in applications where very low device size and cost are paramount and high speed conditions.Finally, Spread Spectrum System for M-ary core module function is divided, chip-based algorithms are given, IP soft core design and verification are implemented by EDA tools, and digital layout design is also implemented.更多还原