We construct new families of error-correcting codes based on Gallager’s low-density parity-check codes, which we call irregular codes. When decoded using belief propagation, our codes can correct more errors than previously known low-density parity-check codes. For example, for rate 1/4 codes on 16,000 bits over a binary symmetric channel, previous low-density parity-check codes can correct up ...

EDGE has enabled the GSM network to offer third generation services as part of the UMTS core network. This is due to the introduction of 8PSK modulation and the recent specification of interfaces from the GERAN to the UMTS core network. This paper studies further improvements to the spectral efficiency and capacity of EDGE through the use of more sophisticated adaptive modulation schemes based ...

In this paper, the combination of equalization and turbo decoding is studied. In the iterative decoding of a product code in block turbo coding system, the equalization process is performed within the iteration loop. The present study aims to investigate the decision feedback equalizer (DFE) incorporated in the iterative decoding. Simulation results show that the more severe the channel interfe...

we present an approach to design of fault tolerant computing systems. in this paper, a technique is employed that enable the combination of several codes, in order to obtain flexibility in the design of error correcting codes. code combining techniques are very effective, which one of these codes are turbo codes. the algorithm-based fault tolerance techniques that to detect errors rely on the c...

This paper presents a new low cost e-mail system for the HF band (3–30 MHz) based on free software and commodity hardware. The core of the system is a 2500 bps OFDM data modem enhanced by turbo codes and a powerful ARQ protocol. The modem has been deeply tested with a Watterson HF channel simulator [?, ], studying the impact of different configurable parameters and comparing its codification st...

DBO is a database system that utilizes randomized algorithms to give statistically meaningful estimates for the final answer to a multi-table, disk-based query from start to finish during query execution. However, DBO’s “time ’til utility” (or “TTU”; that is, the time until DBO can give a useful estimate) can be overly large, particularly in the case that many database tables are joined in a qu...