In recent publications about data compression, arithmetic codes are often suggested as the state of the art, rather than the more popular Huuman codes. While it is true that Huuman codes are not optimal in all situations, we show that the advantage of arithmetic codes in compression performance is often negligible. Referring also to other criteria, we conclude that for many applications, Huuman...

We consider linear error correcting codes associated to higher-dimensional projective varieties defined over a finite field. The problem of determining the basic parameters of such codes often leads to some interesting and difficult questions in combinatorics and algebraic geometry. This is illustrated by codes associated to Schubert varieties in Grassmannians, called Schubert codes, which have...

A complete classification is given of all [22, 111 and [24, 121 binary self-dual codes. For each code we give the order of its group, the number of codes equivalent to it, and its weight distribution. There is a unique [24, 12, 61 selfdual code. Several theorems on the enumeration of self-dual codes are used, including formulas for the number of such codes with minimum distance > 4, and for the...

In this paper, the structure of cyclic codes over m 2 of length k 2 for any natural number k is studied. It is proved that cyclic codes over     1 2 n x x Z R m / ] [ of length n = k 2 are generated by at most m elements. Keywords— Codes, Cyclic codes, Ideals, Principal ideal Ring

This paper studies conditions under which the operation of parallel insertion can be reversed by parallel deletion, i.e., when does the equality (L1 ⇐ L2) ⇒ L2 = L1 hold for languages L1 and L2. We obtain a complete characterization of the solutions in the special case when both languages involved are singleton words. We also define comma codes, a family of codes with the property that, if L2 i...

q–ary codes capable of correcting all unidirectional errors of certain level 1 ≤ l ≤ q − 2 are considered. We also discuss some related extremal combinatorial problems.

For a ternary [n, k, d] code C with d ≡ 1 or 2 (mod 3), k 3, the diversity (Φ0,Φ1) given by Φ0 = 1 2 ∑ 3|i, i =0 Ai, Φ1 = 1 2 ∑ i ≡0, d (mod 3) Ai is important to know about the extendability of C, where Ai stands for the number of codewords with weight i. As a continuation of [T. Maruta, Extendability of ternary linear codes, Des. Codes Cryptogr. 35 (2005) 175–190], we prove all the conjecture...

When the Alamouti code is applied (as a space-time block code) to an OFDM system with transmit diversity, the simple Alamouti decoding requires that each subchannel is flatfading and constant over two symbol periods(Alamouti codeword period). The second requirement makes the Alamouti decoding scheme not suitable for time varying channels. In this paper, we propose a new decision directed receiv...

In this paper, we analyze the performance of space-time block codes which enable symbolwise maximum likelihood decoding. We derive an upper bound of maximum mutual information (MMI) on space-time block codes that enable symbolwise maximum likelihood decoding for a frequency non-selective quasi-static fading channel. MMI is an upper bound on how much one can send information with vanishing error...

In magnetic recording channels, a standard code architecture consists of an outer Reed-Solomon code in concatenation with an inner parity code. The inner parity code is used to detect and correct commonly occurring error events. Generally, a parity code with short block length performs better, as multiple error events within one block and, consequently, miscorrection are less likely. In this pa...