Constant-weight code

About: Constant-weight code is a research topic. Over the lifetime, 4706 publications have been published within this topic receiving 69062 citations.

Code Combining--A Maximum-Likelihood Decoding Approach for Combining an Arbitrary Number of Noisy Packets

Abstract: It is well known that if the data rate is chosen below the available channel capacity, error-free communication is possible. Furthermore, numerous practical error-correction coding techniques exist which can be chosen to meet the user's reliability constraints. However, a basic problem in designing a reliable digital communication system is still the choice of the actual code rate. While the popular rate-1/2 code rate is a reasonable, but not optimum, choice for additive Gaussian noise channels, its selection is far from optimum for channels where a high percentage of the transmitted bits are destroyed by interference. Code combining represents a technique of matching the code rate to the prevailing channel conditions. Information is transmitted in packet formats which are encoded with a relatively high-rate code, e.g., rate 1/2, which can be repeated to Obtain reliable communications when the redundancy in a rate-1/2 code is not sufficient to overcome the channel interference. The receiver combines noisy packets (code combining) to obtain a packet with a code rate which is low enough such that reliable communication is possible even for channels with extremely high error rates. By combining the minimum number of packets needed to overcome the channel conditions, the receiver optimizes the code rate and minimizes the delay required to decode a given packet. Thus, the receiver adapts to the actual jammer-to-signal (J/S) ratio which is critical when the level of interference J is not known a priori.

A DC-balanced, partitioned-block, 8B/10B transmission code

Abstract: This paperd escribes a byte-oriented binary transmission code and its implementation. This code is particularly well suited for high-speed local area networks and similar data links, where the information format consists of packets, variable in length, from about a dozen up to several hundred 8-bit bytes. The proposed transmission code translates each source byte into a constrained 10-bit binary sequence which hase excellent performance parameters near the theoretical limits for 8B/10B codes. The maximum run length is 5 and the maximum digital sum variation is 6. A single error in the encoded bits can, at most, generate an error burst of length 5 in the decoded domain. A very simple implementation of the code has been accomplished by partitioning the coder into 5B/6B and 3B/4B subordinate coders.

A class of optimal minimum odd-weight-column SEC-DED codes

Abstract: The class of codes described in this paper is used for single-error correction and double-error detection (SEC-DED). It is equivalent to the Hamming SEC-DED code in the sense that for a specified number k of data bits, the same number of check bits r is used. The minimum odd-weight-column code is suitable for applications to computer memories or parallel systems. A computation indicates that this code is better in performance, cost and reliability than are conventional Hamming SEC-DED codes.

Byte oriented dc balanced (0,4) 8b/10b partitioned block transmission code

Abstract: A binary DC balanced code and an encoder circuit for effecting same is described, which translates an 8 bit byte of information into 10 binary digits for transmission over electromagnetic or optical transmission lines subject to timing and low frequency constraints. The significance of this code is that it combines a low circuit count for implementation with excellent performance near the theoretical limits, when measured with the commonly accepted criteria. The 8B/10B coder is partitioned into a 5B/6B plus a 3B/4B coder. The input code points are assigned to the output code points so the number of bit changes required for translation is minimized and can be grouped into a few classes.

A note on error detection codes for asymmetric channels

Abstract: Some new codes are described which are separable and are perfect error detection codes in a completely asymmetric channel. Some results are given of comparisons between one simple form of the code in which the check bits correspond to the sum of ones in the information bits and the four out of eight code. The new code is found to compare favorably in error detection capability in several cases. In addition, some more complex codes of this type are indicated.