# Message Redundancy

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

## Message Redundancy

a concept in information theory. The presence of redundancy in a recording of messages from an information source is manifested in the possibility of writing the messages more briefly on the average using the same characters (that is, replacing the code with another using the same alphabet). For example, if the messages under consideration are sequences of characters 0 and 1 in which 1 is encountered, on the average, once per 10 characters, then the notation can be cut almost in half by using coding according to the rule

00 → 0,01 → 10,10 → 110,11 → 111

The maximum share of redundant characters is determined by the statistical characteristics of the message source under consideration and is also called its redundancy. In this meaning, the message redundancy R is determined according to the formula R = 1 – H/log2m, where m is the number of letters in the alphabet, and H is the entropy of the source per letter of the message. In the example cited above, the message redundancy may be calculated as equal to 0.53. Minimum redundancy, R = 0, is found only for a sequence in which the characters are independent and can be equal to any of the m letters of the alphabet with a probability of 1/m.

The question of evaluating the redundancy of specific forms of messages (for example, written and oral speech, phototelegrams, and television pictures) is of practical importance. The magnitude of message redundancy in them is usually significant. For example, the message redundancy of written English speech is not less than 0.6. Great redundancy makes possible easier recognition of transmitted messages where there is interference in the channels of communication. From this point of view it is not always desirable to reduce message redundancy.

IU. V. PROKHOROV

References in periodicals archive ?
(iv) We also present a message redundancy control model to avoid generating unnecessary redundant message copies, thus further controlling message redundancy.
Before presenting our DGA routing algorithm, we first define two groups: Ego Group and Social Group in this section, and then introduce our social group based flooding model and message redundancy control model.
Now, we describe the detailed message redundancy model as follows.
With the vector Y, we use (25) to compute the message redundancy ratio MR(kj) for node j:
In this case, node j should not be selected as next hop relay node for avoiding message redundancy. On the contrary, node j is considered to be a good choice if the value of M[R.sub.(i,j)] is close to 0 since node i and node j have different social circles in that case.
In addition, the proposed message redundancy control model further helps DGA to get a lower overhead ratio.
Section 3 analyzes the message redundancy of MPR and introduces our inspiration for improving the MPR scheme.
Analysis of Message Redundancy in MPR and Inspiration for Improving the MPR Scheme
To analyze intuitively the message redundancy of MPR in broadcasting, we consider a scenario of message propagation in the miniature of a typical unstructured P2P network.
In order to focus on the problem of message redundancy in MPR when broadcasting, in this paper we assume a simplified network model where there is no message failure, where messages are delivered instantly and where each peer has a unique identity assigned by the system.
As can be seen from the above analysis of message redundancy that although the MPR technique reduces greatly the number of retransmissions of pure flooding, the scheme still brings heavy extra message load to the P2P applications which are generally built on the complex network with characters of power-law distribution.
To better illustrate the scheme of LMPR and show its improvement over MPR, we still take the network scenario given in Section 3.1 as an example, presenting the process of message propagation in scheme of LMPR and analyzing its message redundancy in this subsection.
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