New Design of Iterative Non-linear Equalizer with Parallel Concatenation Convolutional Code PC 3 Muhanned Al-Farras Dr.Ziad M. A. Ismail Gulf University, kingdom of Bahrain Gulf University, kingdom of Bahrain Muhanned.alfarras@gmail.com ziadism@gmail.com Prof. Siddeeq Y. Ameen Sefwan Alrawi Gulf University, kingdom of Bahrain Gulf University, kingdom of Bahrain siddeeq_ameen60@yahoo.com sefwan.alrawi@gmail.com Abstract This paper focuses exclusively on new proposed model, which is joining equalizer with turbo decoder over mobile frequency selective channel. Separating between equalizer and decoder is presented in the system for comparison where there is no feedback connection between them. The proposed model depends on Log-MAP algorithm with few modification of soft in soft out SISO output, from PC 3 decoder. Proposed model uses hard decision bit for LLR code bit and feedback to the non-linear equalizer. The gain earned at different frame length and different number of iterations is between 1- 0.2 dB and this gain is earned form joining the priori code bits LLR the decoder to be fed back to the non-linear equalizer. These bits enhance the decision for non-linear equalizer leading to canceling the ISI iteratively. 1. Introduction The proposed third generation wireless system, such as the Universal Mobile Telecommunication System (UMTS) have to provide a “ any where any time ” service to support variable data rate from (348 kbps) for business (Indoor) to up( 2 Mbps ) for local high bit rate ( Indoor ). Some of the data services require highly reliable communication having bit error rates less than (10 -5 ). Turbo codes are promising candidates for high-bit-rate data applications in Wide- bandwidth Code Division Multiple Access (W-CDMA) based third generation mobile radio system. [1, 2] Parallel concatenated interleaved codes popularly known as “ turbo codes ” introducing have been shown to perform near Shannon limit on the Additive White Gaussian Noise (AWGN) channel. This powerful channel coding technique has also been studied for digital communication system over more problematic wireless fading channels, but mainly for flat fading channel and short form speech transmission with narrow band direct sequence code division multiple access (DS – CDMA) system. Turbo Coding was introduced in (1993) by Berron, Glavenx, and Thitimmajashima [3], who reported extremely impressive results for a code with along frame length. Since its invention, turbo coding has evolved at an unprecedented rate and has reached maturity within just few years due to the intensive research efforts of the turbo coding community. As a result, turbo coding has also found its way into standardized system third Generation (3G) Mobile Radio System [2]. Equalization is a technique that compensates intersymbol interference ISI created by multipath within time dispersive channels. Iterative equalization and decoding are employed in the presence of intersymbol interference ISI and minimize the BER. The equalizer processes the signal based on information about the channel while the decoding procedure used the controlled redundancy in the code for further improvement [4]. 2. Non-Linear Equalizer with Isolated Turbo Decoding (System I) When the channel introduces intersymbol interference such as mobile frequency selective channel, the equalization method constitutes the first step in the receiver. The equalization which is separated from decoding processing. The nonlinear equalizer is used to cancel the intersymbol interference at the input to turbo decoder. The received y k r , is passed to the equalizer to remove ISI. Therefore turbo decoder received noisy signal k r after it is interleaved, and then perform the decoding process as shown in Figure 1. There is no feedback loop between equalizer and turbo decoders within this system [5]. k d  y k r Figure 1. Non-linear equalizer with turbo decoder Turbo Decoder Channel interleaver Non-linear equalizer