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In this paper, area-efficient Vedic multiplier is designed using modified Carry Select Adder (CSLA). As the multiplication is nothing but subsequent addition process, adder is important block in the design of multiplier. Simple Ripple Carry adder (RCA) can be used for implementing multiplier. Digital adder has problem of carry propagation, thus carry select adder is used instead. Carry select adder is known to be one of the fastest adder structures. Here novel technique that is Vedic multiplier is implemented instead of normal multipliers like add and shift multiplier, array multiplier etc. Here multiplier is designed based on ancient Vedic multiplication technique. The goal of this paper is to design area-efficient Vedic multiplier based on crosswise and vertical algorithms. Conventional CSLA designs are compared with proposed design to prove its efficiency. On an average, modified CSLA has 29 % less area than Binary to Excess one Converter (BEC) based CSLA for different bit widths. Proposed Vedic multiplier is designed using modified CSLA, which has approximately 10 % less area than BEC based Vedic multiplier. It shows improved performance in terms of area. Proposed design is also compared with the Booth multiplier. Proposed multiplier showed more excellent results than Booth multiplier.

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Turbo decoding for 3GPP-LTE wireless communication standard is most challenging task to reduce computational complexity. This paper presents 8-state trellis VHDL implementation of radix-2 and radix-4 form. In a practical system, the original MAP algorithm is too complex for implementation. All the branch metrics required for calculating LLR values are stored in a RAM. Max * function is implemented with correction factor to improve performance. The proposed, implemented algorithm is almost identical to max * function. With increasing demand for different data rate and services for communication system reconfigurability is important. So implementation is targeted towards Xilinx Virtex E FPGAs. The turbo decoder uses soft in soft out (SISO) decoders to decode one code word.

This paper presents a low complexity interleaver design that facilitates high throughput Turbo decoding required for next generation wireless systems. When a parallel decoder structure is considered, interleaver design is the most important issue. In such parallel decoder, the contention problem occurs when more than one extrinsic value references to the same memory block for read or write purpose. This paper focuses on the alternate method for QPP interleaver which shows improved BER performance for large frame size. Bit reversed indexing is used to generate interleaved addresses. A counter is used to generate sequential address as well as interleaved address. The number of address lines of memory which stores data , depends upon frame size of data. In this paper, a comparison is made between best proved interleaver and proposed interleaver on the basis of BER performance for different number of iterations, different frame size and different decoding algorithms. General TermsInterleaver, Turbo Decoder, Bit reverse indexing.