Performance Study of DS—SFH ／SSMA Communication with Multipath Diversity

ＰｅｒｆｏｒｍａｎｃｅＳｔｕｄｙｏｆＤＳ－ＳＦＨ／ＳＳＭＡＣｏｍｍｕｎｉｃａｔｉｏｎｗｉｔｈＭｕｌｔｉｐａｔｈＤｉｖｅｒｓｉｔｙＴａｎＺｈｅｎｈｕｉ；ＧｕａｎＨａｏ（ＮｏｒｔｈｅｒｎＪｉａｏｔｏｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１０００４４）Ａ...     

Cross-layer in MIMO-OFDM System with Adaptive Modulation and Coding：Design and Analysis

The queuing performance of the cross-layer system with Space-time block code （STBC） over Multi- input-multi-output （MIMO） channel is analyzed. The Adaptive modulation and coding （AMC） in physical layer and finite length of buffer in data-link layer are combined with this model. A simple cross-layer design and the queue state process are proposed based on finite state 1V[arkov channel model~ which is to solve the service process. The proposed cross-layer design is also incorporated with STBC to further improve the system performance. Simulation results illustrate the dependence of system performance on various parameters, and quantify the performance gain due to cross-layer optimization. The adjustment of target packet loss rate of adaptive modulation coding in physi- cal layer can maximize average throughput of the system, meanwhile a significant improvement of the system perfor- mance is brought.     

室内无线差分网格编码直扩多址系统的性能分析

本语言分析了室内无线多径衰落信道中差分网格编码调制直扩多址通信系统的性能，分析中采用特征函数法和留数定理计算序列差错概率，用高斯近似分析多址干扰和多径干扰，本文最后给出了误码率的理论分析结果和计算机模拟结果，并与常规的未编码直扩系统性能对比。     

Bit-Interleaving in Fast FH/SSMA Systems with M-FSK Modulation

The effects of bit-interleaving on the performance of convolutional codes and turbo codes in fast frequency- hop/spread-spectrum multiple-access systems with M-FSK modulation are investigated. It is observed that bit-interleaving induces two counter-acting forces on decoder performance. On the one hand, bit-interleaving disperses consecutive error bits caused by a noisy M-ary signal and makes the errors more correctable. On the other hand, the same measure makes it difficult for the decoder to make use of the bit dependency information. Both theoretical upper bounds and simulation results show that bit- interleaving degrades the performance of soft-decision decoded convolutional codes and turbo codes.     

DS/CDMA系统扩频序列相位

DS/CSMA系统接收机区别于常规通信系统的最大特点是首先需要解扩,而解扩的关键是本地地址码与发端地址码的同步.同步建立的过程,通常包括对信号的捕获和跟踪,而捕获是关键的第一步.本方结合实际中的应用条件,就相位捕获电路的实现方法及其中的关键技术进行了探讨和分析.     

DS/SSMA communication system with trellis coding and CPM

A direct-sequence spread spectrum multiple access (DS/SSMA) communication system employing continuous phase modulation (CPM) and trellis coding is described and analyzed to obtain an estimate of the error probability. The trellis code provides significant coding gain while the CPM signal format gives desirable spectral properties. The analysis shows that significant improvement in error probability over the standard binary DS/SSMA system can be achieved with relatively simple codes     

Chips波形对DS/SSMA扩频多址系统的性能影响分析

本文给出了直接序列扩频多址通信系统（ＤＳ／ＳＳＭＡ）采用各种切普（Ｃｈｉｐｓ）波形时信号的功率谱特点,并对它们在ＡＧＷＮ信道下的多址性能进行了分析,通过高斯近似及ＭｏｎｔｅＣａｒｌｏ仿真得到了系统的平均误比特率性能。     

A Novel EKF-Based Recovery in DS Scheme for DS/CDMA Systems Tracking Code Delay

Classical delay-lock loops (DLL) have beenwidely considered for code synchronization purposes inDS/CDMA systems, although they have not been devised foroperation when channel fading is present. This paper describes a new code synchronizationscheme based on a previously proposed extended Kalmanfilter (EKF) approach. The scheme proposed in this paperis able to operate under low signal-to-interference ratios (SIR), usual at the receiver input incellular CDMA mobile environments, and it outperformsthe behavior of previously proposed EKF-based schemes,which failed in such environments. Performance results under realistic mobile environment conditionsare shown in terms of the mean time to lose lock (MTLL)and the tracking error variance ² for a wide range ofSIR values and under Rayleigh fading. Moreover, the Cramer-Rao lower boundon ² is also computed inorder to validate the results obtained viasimulations.     

无冲突话音/数据综合业务分组预约多址(CF-IPRMA)协议及其性能

本文提出了无冲突话音／数据综合业务的ＰＲＭＡ协议：ＣＦ－ＩＰＲＭＡ协议,并利用马尔可夫链模型法,对ＣＦ－ＩＰＲＭＡ协议中的数据通信性能进行了分析;分析结果表明,该协议在保证话音通信质量的前提下,具有较高的数据业务通过率。     

Reverse link interference modeling and outage analysis for DS/CDMA cellular systems

In this paper, we analyze multi-cell multi-user interference through a new approach. The area averaged probability density function (PDF) of interference power from one active user is evaluated. Differing from the distance membership determination, the statistical effect of hand-off is considered. The Gamma distribution is proposed to model the area averaged PDF of the interference power of an active user. An efficient method for evaluating system performance is developed. Differing from the Gaussian approximation, this method is very effective and accurate for both a large number and a small number of users. The performance of a CDMA cellular system with high quality requirements and mixed traffic is evaluated.This research was supported by a grant from the Canadian Institute for Telecommunications Research under the NCE program of the Government of Canada. This paper was presented in part at the IEEE PIMRC '94 Conference, The Hague, The Netherlands, Sept. 1994.     

A Neural Network Approach to Blind Estimation of PN Spreading Sequence in DS/SS Signals

As the power spectrum density of direct sequence spread spectrum (DS/SS or DS), signals is often much lower than the noises’, the DS signals have the ability to resist interception and interference. But in point of fact, if we have get some parameters of the DS signals, including information symbol period, chip period of the pseudo noise (PN) sequence, we can estimate the PN sequence in DS signals blindly, this has great value for management or interception of DS communications. Ref.[1…     

混合DS／SFH CDMA扩频通信系统中的自适应跳频

文章基于进一步提高跳扩频通信系统的抗干扰性能，提出了在混合直接序列扩频（DS／SFHCDMA）通信系统中实现自适应跳频（AFH）方式，给出了基于优化考虑的自适应跳频地址编码方法，在给出信道仿真参数的前提下，对自适应跳频系统的误码性能进行了分析。结果表明自适应方式优于传统方式。