[Sobana, 3(1): January, 2014] ISSN: 2277-9655 Impact Factor: 1.852 http: // www.ijesrt.com(C)International Journal of Engineering Sciences & Research Technology [1-5] IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY Design and Implementation of Map Decoding for DB Convolutional Turbo Decoder S.Sobana *1 , M.Kasthuri 2 *1,2 Associate Professor, Department of ECE, PSNA College of Engineering & Technology, Dindigul, India sobanaa@gmail.com Abstract This paper proposed an approximate Gaussian density evolution based MAP Decoder for high performance wireless communication. This paper considers a three node (source (S), relay (R) and destination (D)) wireless cooperative communication system, which can be considered as a building block for larger wireless networks. This proposed work adaptively changes the code and Modulation format according to the channel conditions, to improve performance without adding more network cooperation overhead. In proposed architecture, the higher throughput, less power consumption and less area are achieved. The architecture is implemented using spartan3E family and XC3S500E device in Xilinx 9.2i.The proposed system is written in VHDL language and synthesized in Xilinx 9.2i and stimulated using Modelsim 5.7. In 200MHz operation the Coprocessor consumes 79mW in static and 96mW in dynamic in the total summation of 175mW. Keywords: MAP Decoder, SB/DB Decoding, Likelihood Ratio, Interleaver, CTC I. Introduction With rapid growth of multimedia services, the convolutional turbo code (CTC) has been widely adopted as one of forward error correcting (FEC) schemes of wireless standards to have a reliable transmission over noisy channels. Single-binary (SB) CTC, proposed in 1993 [2], has been the well-known FEC code that can achieve high data rates and coding gains close to the Shannon limit. The SB CTC code has been adopted in the FEC schemes of wideband code division multiple access (WCDMA) [3], high-speed downlink packet access (HSDPA) [3], and long term evolution (LTE) [3]. In 1999, non-binary CTC [4] was introduced to achieve superior performance than the SB CTC. In recent years, double-binary (DB) CTC has been adopted in advanced wireless communication standards, such as worldwide interoperability for microwave access (WiMAX) [5]. Some CTC decoders have been implemented as application-specific integrated circuits (ASICs), such as the HSDPA CTC decoder [6] and WiMAX CTC decoder [6]. Recently, high-end portable/mobile devices become prevalent in wireless markets. There are large growing emergence and demands for an inexpensive solution to access the ubiquitous wireless services. Meanwhile, these wireless standards, such as 3GPP and WiMAX standards, adopted CTC schemes with different coding parameters and different throughput rates [9], [10]. To deal with the accelerated evolution of these standards, the multi standard platforms which can seamlessly work across the multiple standards were proposed in [8]. Hence, a CTC decoding accelerator which works in the multi standard platforms is desired to achieve the smooth migration for the multiple wireless applications. The CTC decoder needs the hardware implementation for MAP decoding in an important issues of memory organization. In particular, the power reduction of state metrics cache (SMC) is critical for MAP decoders. With the SB CTC decoding, the power consumption of the SMC is reduced. Some researchers have been proposed reduction in power consumption. The reverse computations significantly reduce SMC power consumption with reversion flag caches and reversion checkers. However, the reversion checker and reversion flag cache prolong the critical path or decoding cycles. In addition, the computational complexities of the reverse computations are increased dramatically when the reverse computations are extended from the SB to the DB MAP. II. Literature Survey Cooperative and relay communication has received much attention recently [3]–[6] due to the potential performance improvement. At the network level, relays can extend wireless network coverage if a direct source-to destination link does not exist [7]. At the physical level, the use of relays can achieve the diversity gains offered by multiple antenna space-time systems through using several relay nodes, possibly with only one