Improved closed-form bounds on the performance of convolutional codes with correlated Rayleigh fading

New bounds on the probability of bit error are presented for a coded communication system with binary antipodal modulation and soft-decision maximum-likelihood decoding over a correlated Rayleigh-fading channel. The bounds are closed-form expressions in terms of the code\u27s transfer function; they are illustrated by considering a system using convolutional encoding. A long-standing conjecture regarding the worst-case error event in correlated Rician fading is proven for the special case of correlated Rayleigh fading, and it is used in the development of some of the new bounds. The bounds are shown to be tighter than previously developed closed-form bounds for communications using convolutional codes in correlated Rayleigh fading

Performance of turbo coded DS-CDMA systems in correlated and uncorrelated satellite communication channels

Word processed copy.Includes bibliographical references (leaves 82-88).This thesis aims at presenting the perfonnance of turbo codes in the correlated and uncorrelated satellite fading channel. Turbo codes are known to give very good perfonnance results in A WGN channels, especially for very large input message length codes or interleaver sizes. It can be shown that good perfonnance of the turbo codes can be achieved with small interleaver sizes in a satellite channel

Cooperative Regions For Coded Cooperation Over Time-Varying Fading Channels

The performance analysis of coded cooperation has been mainly focused on two extreme cases of channel variability, i.e. the block-fading (BF) and the fast-fading (FF) model. In more practical propagation environments the fading correlation across time depends on the level of user mobility. This paper analyzes the effects of time-selective fading on the performance of coded cooperation by providing an analytical framework for the error rate evaluation as a function of the mobility degree of the mobile station (MS) and of the quality of the inter-MS channel. The purpose is to evaluate the conditions on the propagation settings where the additional exploitation of spatial diversity (when time-diversity is available) provided by cooperative transmission is able to enhance substantially the performance of the non-cooperative transmission. We show that coded cooperation can outperform the non-cooperative (coded and bit-interleaved) transmission only up to a certain degree of mobility. The cooperative region is defined as the collection of mobility settings for which coded cooperation can be regarded as a competitive strategy compared to non-cooperative transmission. Contrary to what has been previously shown for BF channels, we demonstrate that the inter-MS channel quality plays a key role in the definition of the cooperative region

非直交多元接続のための高信頼空間変調

　マルチユーザ空間変調（SM: Spatial Modulation）では，SM信号の疎性を用いた圧縮センシングによるマルチユーザ検出が研究されているものの，受信機においてチャネル情報が完全に既知であるという条件の下で議論されている．実際には受信機側でチャネル情報を推定し，推定したチャネル情報を用いて復調処理を行う．推定したチャネル情報の精度は復調の精度に影響を及ぼすため，チャネル推定は重要なものであり考慮しなければならない．　そこで本研究ではチャネル推定を，ブロックスパース性を有する信号の再構成問題として扱い，ブロックスパース性を考慮した複素数近似メッセージ伝播法（BS-CAMP: Block-Sparse Complex Approximate Message Passing）によって信号の再構成を行う方法を提案する．BS-CAMPは受信機が送信信号に含まれる非零要素の個数を事前に知る必要がない再構成アルゴリズムとなっており，ランダムアクセス方式にも適用可能である．計算機シミュレーションより，BS-CAMPによるチャネル推定の精度やスループット特性への影響を示す．　さらに，高信頼な通信を実現するにはチャネル推定だけでなく誤り訂正符号が重要となる．そこで併せて本研究ではSMに誤り訂正符号化を組み合わせたものの一つである，ターボトレリス符号化空間変調（SM-TTC: SM with Turbo Trellis-Coding）における符号の最適化及び性能解析を行った．具体的には，シンボルベースEXIT（Extrinsic Information Transfer）チャートを用いた低演算符号探索法によって，演算量を低減しながら最良の特性を示す符号を探索する．計算機シミュレーションより，探索した符号を用いたSM-TTCが従来のものよりも優れていること，および提案手法が従来の符号探索法よりも低計算量で符号探索が可能であることを示す．電気通信大学201

Super-orthogonal space-time turbo codes in Rayleigh fading channels.

Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2005.The vision of anytime, anywhere communications coupled by the rapid growth of wireless subscribers and increased volumes of internet users, suggests that the widespread demand for always-on access data, is sure to be a major driver for the wireless industry in the years to come. Among many cutting edge wireless technologies, a new class of transmission techniques, known as Multiple-Input Multiple-Output (MIMO) techniques, has emerged as an important technology leading to promising link capacity gains of several fold increase in data rates and spectral efficiency. While the use of MIMO techniques in the third generation (3G) standards is minimal, it is anticipated that these technologies will play an important role in the physical layer of fixed and fourth generation (4G) wireless systems. Concatenated codes, a class of forward error correction codes, of which Turbo codes are a classical example, have been shown to achieve reliable performance which approach the Shannon limit. An effective and practical way to approach the capacity of MIMO wireless channels is to employ space-time coding (STC). Space-Time coding is based on introducing joint correlation in transmitted signals in both the space and time domains. Space-Time Trellis Codes (STTCs) have been shown to provide the best trade-off in terms of coding gain advantage, improved data rates and computational complexity. Super-Orthogonal Space-Time Trellis Coding (SOSTTC) is the recently proposed form of space-time trellis coding which outperforms its predecessor. The code has a systematic design method to maximize the coding gain for a given rate, constellation size, and number of states. Simulation and analytical results are provided to justify the improved performance. The main focus of this dissertation is on STTCs, SOSTTCs and their concatenated versions in quasi-static and rapid Rayleigh fading channels. Turbo codes and space-time codes have made significant impact in terms of the theory and practice by closing the gap on the Shannon limit and the large capacity gains provided by the MIMO channel, respectively. However, a convincing solution to exploit the capabilities provided by a MIMO channel would be to build the turbo processing principle into the design of MIMO architectures. The field of concatenated STTCs has already received much attention and has shown improved performance over conventional STTCs. Recently simple and double concatenated STTCs structures have shown to provide a further improvement performance. Motivated by this fact, two concatenated SOSTTC structures are proposed called Super-orthogonal space-time turbo codes. The performance of these new concatenated SOSTTC is compared with that of concatenated STTCs and conventional SOSTTCs with simulations in Rayleigh fading channels. It is seen that the SOST-CC system outperforms the ST-CC system in rapid fading channels, whereas it maintains performance similar to that in quasi-static. The SOST-SC system has improved performance for larger frame lengths and overall maintains similar performance with ST-SC systems. A further investigation of these codes with channel estimation errors is also provided

Some fundamental issues in receiver design and performance analysis for wireless communication

Ph.DDOCTOR OF PHILOSOPH