WiMAX based on IEEE Std. 802.16 carries high data rates and large coverage to wireless networks. It provide high speed wireless broadband connectivity building the gap between 3G and Wireless LAN (WLAN).The main focus of this paper is on 802.16d OFDM PHY layer. The simulation will compare the performance of SF and STF – OFDM over different SUI channel models. Forward error correction is used to...

AbstructIterative decoding of two-dimensional systematic convolutional codes has been termed “turbo” (de)coding. Using log-likelihood algebra, we show that any decoder can be used which accepts soft inputs-including a priori values-and delivers soft outputs that can be split into three terms: the soft channel and a priori inputs, and the extrinsic value. The extrinsic value is used as an a prio...

One general class of attacks on stream ciphers is correlation attacks. Most of previous results regarding performance of correlation attacks have been based entirely on simulations. In this paper, we use random coding bounds for convolutional codes to give a theoretical analysis of a previously proposed correlation attack based on convolutional codes. The results from the theoretical derivation...

In this work we make a detailed look at the algebraic structure of convolutional codes using techniques of linear systems theory. In particular we study the input-state-output representation of a convolutional code. We examine the output-controllability property and we give conditions for this property. At the end of the paper is presented a brief introduction to the analysis of output controll...

In this paper we will study a class of concatenated coded communications systems which are built from convolutional codes and interleavers. These systems include as special cases both the classical tubo codes [1][2] and the serial concatentation of convolutional codes [4]. Our main results are a method for computing a conjectured interleaving gain exponent and for optimizing the effective free ...

Abstract Error correcting codes can play a key role in improving the efficiency and reliability of wireless communications. Concatenated codes have the advantages that: 1) breaking the task into stages simplifies decoding, and 2) performance is good against clustered bit errors, fading and bursty interference. Reed-Solomon codes (maximum distance codes) have been popular as an outer code of con...

A new class of of rate 1/2 convolutional codes called strongly MDS convolutional codes are introduced and studied. These are codes having optimal column distances. Properties of these codes are given and a concrete construction is provided. This construction has the ability to correct δ errors in any sliding window of length 4δ + 2 whereas the best known MDS block code with parameters [n, n/2],...