Error Correcting Code Techniques

The channel estimation techniques for OFDM systems based on pilot arrangement are investigated. The channel estimation based on comb type pilot arrangement is studied through different algorithms for both estimating channel at pilot frequencies and interpolating the channel. The estimation of channel at pilot frequenc…

For the first time Boolean functions on 9 variables having nonlinearity$241$are discovered, that remained as an open question in literature for almost three decades. Such functions are found by heuristic search in the space of rotation symmetric Boolean functions (RSBFs). This shows that there exist Boolean functions…

• SELÇUK KAVUT

Potentially large storage requirements and long initial decoding delays are two practical issues related to the decoding of low-density parity-check (LDPC) convolutional codes using a continuous pipeline decoder architecture. In this paper, we propose several reduced complexity decoding strategies to lessen the storag…

• ALİ EMRE PUSANE

Low-density parity-check (LDPC) convolutional codes are capable of achieving excellent performance with low encoding and decoding complexity. In this paper, we discuss several graph-cover-based methods for deriving families of time-invariant and time-varying LDPC convolutional codes from LDPC block codes and show how…

• ALİ EMRE PUSANE

Schalkwijk and Kailath (1966) developed a class of block codes for Gaussian channels with ideal feedback for which the probability of decoding error decreases as a second-order exponent in block length for rates below capacity. This well-known but surprising result is explained and simply derived here in terms of a re…

• BARIŞ NAKİBOĞLU

An information-theoretic framework for unequal error protection is developed in terms of the exponential error bounds. The fundamental difference between thebit-wiseandmessage-wiseunequal error protection (UEP) is demonstrated, for fixed-length block codes on discrete memoryless channels (DMCs) without feedback. Effec…

• BARIŞ NAKİBOĞLU

A general information theoretic framework for unequal error protection is developed in terms of exponential error bounds. The qualitative difference between the bit-wise and message-wise unequal error protection (UEP) is demonstrated, for fixed length block codes on DMCs without feedback. Effect of feedback is investi…

Low-density parity-check (LDPC) convolutional codes have been shown to be capable of achieving capacity-approaching performance with iterative message-passing decoding. In the first part of this paper, using asymptotic methods to obtain lower bounds on the free distance to constraint length ratio, we show that several…

• ALİ EMRE PUSANE

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• FERRUH ÖZBUDAK

In a remarkable paper published in 1976, Burnashev determined the reliability function of variable-length block codes over discrete memoryless channels (DMCs) with feedback. Subsequently, an alternativeachievabilityproof was obtained by Yamamoto and Itoh via a particularly simple and instructive scheme. Their idea is…

• BARIŞ NAKİBOĞLU

The original design of standard digital fountain codes assumes that the coded information symbols are equally important. In many applications, some source symbols are more important than others, and they must be recovered prior to the rest. Unequal Error Protection (UEP) designs are attractive solutions for such sourc…

• ŞEFİK ŞUAYB ARSLAN

We introduce an importance sampling (IS) method that successfully simulates the performance of Low density Parity Check (LDPC) Codes in an AWGN channel at very low bit error rates (BERs). By effectively finding and biasing bit node combinations that are the dominant sources of error events, called trapping sets, the d…

• ENVER ÇAVUŞ