A Review :Implementation of Reed Solomon Error Correction & Detec-tion For Wireless Network 802.16

The reed Solomon (255,239) are error-correcting & detecting code. Reed-Solomon codes are the most frequently used digital error control. It is also called as forword error code. The main part of reed-Solomon encoder is the linear feedback shift register that is implemented using VHDL A pipelined RS decoders is proposed of reducing the hardware complexity use the pipelined GFmultiplier in the syndrome computation block, KES block, Forney block, Chien search block and error correction block for provides low com-plexity the extended inversion less Massey-Berlekamp algorithm is used. The extended inversion less Massey-Berlekamp algorithm overcomes both the error locator polynomial and the error evaluator polynomial at the same time

FPGA implementation of Reed Solomon codec for 40Gbps Forward Error Correction in optical networks

Reed-Solomon error correcting codes (RS codes) are widely used in communication and data storage systems to recover data from possible errors that occur during data transfer. A growing application of RS codes is Forward Error Correction (FEC) in the Optical Network (OTN G.709), which uses RS(255,239) to support the OTU-3 (43.018 Gbps) standard. There have been considerable efforts in the area of RS architecture for ASIC implementation. However, there appears to be little reported work on efficient RS codec (encoder and decoder) for Field Programmable Gate Arrays (FPGAs), which has increasing interests in industry. This thesis investigates the implementation and design methodology of the RS(255,239) codec on FPGAs. A portable VHDL code is developed and synthesized for Xilinx\u27s Virtex4 and Altera\u27s StratixII. The FPGA architectures are analyzed and the required design methodologies are adopted to efficiently utilize the available resources. Unfortunately, due to the fixed size of FPGA devices, the RS decoder is not only constrained by the required timing of the system, but also by the size of the targeted device. This research will facilitate the decision-making process for selecting a reconfigurable device for a RS decoder, implementing the Berlekamp-Massey Algorithm

VHDL implementation of reed-solomon coding

Forward Error Correction technique depending on the properties of the system or on the application in which the error correcting is to be introduced. Error control coding techniques are based on the addition of redundancy to the information message according to a prescribed rule thereby providing data a higher bit rate. This redundancy is exploited by decoder at the receiver end to decide which message bit actually transmitted. Reed-Solomon codes are an important sub – class of non binary Bose-Chaudhuri-Hocquenghem (BCH) codes. In digital communication, Reed-Solomon (RS) codes refer to as a part of channel coding that had becoming very significant to better withstand the effects of various channel impairments such as noise, interference and fading. This signal processing technique is designed to improve communication performance and can be deliberate as medium for accomplishing desirable system trade-offs. Galois field arithmetic is used for encoding and decoding of Reed – Solomon codes. Galois field multipliers are used for encoding the information block. The encoder attaches parity symbols to the data using a predetermined algorithm before transmission. At the decoder, the syndrome of the received codeword is calculated. VHDL implementation creates a flexible, fast method and high degree of parallelism for implementing the Reed – Solomon codes. The purpose of this thesis is to evaluate the performance of RS coding system using M-ary modulation over Additive White Gaussian Noise AWGN channel and implementation of RS encoder in VHDL. Computer simulation tool and MATLAB will be used to create and run extensively the entire simulation model for performance evaluation and VHDL is used to implemented the design of RS encoder.

Optical Communication

Optical communication is very much useful in telecommunication systems, data processing and networking. It consists of a transmitter that encodes a message into an optical signal, a channel that carries the signal to its desired destination, and a receiver that reproduces the message from the received optical signal. It presents up to date results on communication systems, along with the explanations of their relevance, from leading researchers in this field. The chapters cover general concepts of optical communication, components, systems, networks, signal processing and MIMO systems. In recent years, optical components and other enhanced signal processing functions are also considered in depth for optical communications systems. The researcher has also concentrated on optical devices, networking, signal processing, and MIMO systems and other enhanced functions for optical communication. This book is targeted at research, development and design engineers from the teams in manufacturing industry, academia and telecommunication industries

Network coded wireless architecture

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 183-197).Wireless mesh networks promise cheap Internet access, easy deployment, and extended range. In their current form, however, these networks suffer from both limited throughput and low reliability; hence they cannot meet the demands of applications such as file sharing, high definition video, and gaming. Motivated by these problems, we explore an alternative design that addresses these challenges. This dissertation presents a network coded architecture that significantly improves throughput and reliability. It makes a simple yet fundamental switch in network design: instead of routers just storing and forwarding received packets, they mix (or code) packets' content before forwarding. We show through practical systems how routers can exploit this new functionality to harness the intrinsic characteristics of the wireless medium to improve performance. We develop three systems; each reveals a different benefit of our network coded design. COPE observes that wireless broadcast naturally creates an overlap in packets received across routers, and develops a new network coding algorithm to exploit this overlap to deliver the same data in fewer transmissions, thereby improving throughput. ANC pushes network coding to the signal level, showing how to exploit strategic interference to correctly deliver data from concurrent senders, further increasing throughput. Finally, MIXIT presents a symbol-level network code that exploits wireless spatial diversity, forwarding correct symbols even if they are contained in corrupted packets to provide high throughput reliable transfers. The contributions of this dissertation are multifold. First, it builds a strong connection between the theory of network coding and wireless system design. Specifically, the systems presented in this dissertation were the first to show that network coding can be cleanly integrated into the wireless network stack to deliver practical and measurable gains. The work also presents novel algorithms that enrich the theory of network coding, extending it to operate over multiple unicast flows, analog signals, and soft-information.(cont.) Second, we present prototype implementations and testbed evaluations of our systems. Our results show that network coding delivers large performance gains ranging from a few percent to several-fold depending on the traffic mix and the topology. Finally, this work makes a clear departure from conventional network design. Research in wireless networks has largely proceeded in isolation, with the electrical engineers focusing on the physical and lower layers, while the computer scientists worked up from the network layer, with the packet being the only interface. This dissertation pokes a hole in this contract, disposing of artificial abstractions such as indivisible packets and point-to-point links in favor of a more natural abstraction that allows the network and the lower layers to collaborate on the common objectives of improving throughput and reliability using network coding as the building block. At the same time, the design maintains desirable properties such as being distributed, low-complexity, implementable, and integrable with the rest of the network stack.by Sachin Rajsekhar Katti.Ph.D

High speed RS(255, 239) decoder based on LCC decoding

Algebraic Soft-Decision Decoding (ASD) of Reed-Solomon (RS) codes provides higher coding gain over the conventional hard-decision decoding (HDD), but involves high computational complexity. Among the existing ASD methods, the Low Complexity Chase (LCC) decoding is the one with the lowest implementation cost. LCC decoding is based on generating 2 ¿ test vectors, where ¿ symbols are selected as the least reliable symbols for which hard-decision or the second more reliable decision are employed. Previous decoding algorithms for LCC decoders are based on interpolation and re-encoding techniques. On the other hand, HDD algorithms such as the Berlekamp-Massey (BM) algorithm or the Euclidean algorithm, despite of their low computational complexity, are not considered suitable for LCC decoding. In this paper, we present a new approach to LCC decoding based on one of these HDD algorithms, the inversion-less Berlekamp-Massey (iBM) algorithm, where the test vectors are selected for correction during decoding on occurrence of hard-decision decoding failure. The proposed architecture when applied to a RS(255, 239) code with ¿=3, saves a 20.5% and 2% of area compared to the LCC with factorization and a factorization-free decoder, respectively. In both cases, the latency is reduced by 34.5%, which is an increase of throughput rate in the same percentage since the critical path is the same in all the competing architectures. So an efficiency of at least 56% in terms of area-delay product can be obtained, compared with previous works. 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