C. C. R. Jones

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A construction method for protograph-based LDPC codes that simultaneously achieve low iterative decoding threshold and linear minimum distance is proposed. We start with a high-rate protograph LDPC code with variable node degrees of at least 3. Lower rate codes are obtained by splitting check nodes and connecting them by degree-2 nodes. This guarantees the(More)
This paper provides a construction method for low-rate low density parity check codes. Inspired by recently proposed accumulate-repeat-accumulate (ARA) codes, and hybrid concatenated codes, in this paper we extend the construction to low rates. Such codes can be viewed as hybrid concatenations of simple modules such as accumulators, repetition codes,(More)
In this paper, we apply two improved min-sum algorithms, the normalized and offset min-sum algorithms, to the decoding of irregular LDPC codes. We show that the behavior of the two algorithms in decoding irregular LDPC codes is different from that in decoding regular LDPC codes, due to the existence of bit nodes of degree two. We analyze and give(More)
ARA- and protograph-based LDPC codes are capable of achieving error performance similar to randomly constructed codes while enjoying several implementation advantages as a result of their structure. LDPC convolutional codes can be derived from these codes through an unwrapping process. In this paper, we review the unwrapping process as well as the pipeline(More)
Implementation of belief propagation for low-density parity-check codes involves selection of functions possessing manageable dynamic range, topologic considerations for aggregation of these functions such that nodes of varying degree can be efficiently realized, and message passing architectures that offer various alternatives for flexibility and(More)
The U.S. Navy recently developed a version of the Tomahawk Missile that can be retargeted while in flight. This new version, called the Tactical Tomahawk Missile, requires en route monitoring, control, and oversight by human operators. Previous research led to the design, implementation, and testing of a graphical multiuser interface system for human(More)
A network of radiation sensors for the protection of a military base against radiological/nuclear threats has been integrated in a testbed. Two key subsystems of this network are the array of sensitive radiation detectors and the subsystem for notifying the operators of radiation events. The alarm/alert notification subsystem automatically issues(More)
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