This document provides formulas and concepts related to information theory and coding. It defines key information theory terms like self-information, entropy, information rate, bits, Hartley's, nats, extremal entropy, source efficiency, and source redundancy. Formulas are given for calculating each of these terms. The document also provides formulas for calculating the average information content of symbols from different states. Finally, it lists some basic log properties that are important in information theory calculations.
VTU E&C,TCE CBCS[NEW] 5th Sem Information Theory and Coding Module-1 notes(15&17scheme).
1. INFORMATION THEORY AND
CODING
5th SEM E&C
JAYANTHDWIJESH H P M.tech (DECS)
Assistant Professor – Dept of E&C
B.G.S INSTITUTE OF TECHNOLOGY (B.G.S.I.T)
B.G Nagara, Nagamangala Tq, Mandya District- 571448
2. FORMULAS FOR REFERENCE
MODULE –1(INFORMATION THEORY)
Amount of information or Self information.
𝑰 𝑲 = log (
𝟏
𝑷 𝑲
) or 𝑰 𝑲 = 𝐥𝐨𝐠 𝟐 𝟏(
𝟏
𝑷 𝑲
) or I (𝒎 𝑲) = log (
𝟏
𝑷 𝑲
)
Entropy of source or Average information content of the source.
H = 𝑷𝒊 𝐥𝐨𝐠 𝟐 𝟏 (
𝟏
𝑷 𝒊
𝑴
𝒊=𝟏 ) bits/symbol or H = 𝑷 𝑲 𝐥𝐨𝐠 𝟐 𝟏 (
𝟏
𝑷 𝑲
𝑴
𝑲=𝟏 ) bits/symbol or
H(S) = 𝑷𝒊 𝐥𝐨𝐠 𝟐 𝟏 (
𝟏
𝑷 𝒊
𝒒
𝒊=𝟏 ) bits/symbol or H(S) = 𝑷𝒊 𝐥𝐨𝐠(
𝟏
𝑷 𝒊
𝒒
𝒊=𝟏 ) bits/symbol or
H(S) = 𝑷 𝑲 𝐥𝐨𝐠 𝟐 𝟏 (
𝟏
𝑷 𝑲
𝑵
𝑲=𝟏 ) bits/symbol
Information rate or average information rate.
𝑹 𝑺 = 𝒓 𝒔H(S) bits/sec or R= 𝒓 𝒔H bits/sec or R=r H bits/sec
Bits.
𝑰 𝑲 = 𝐥𝐨𝐠 𝟐 𝟏(
𝟏
𝑷 𝑲
) bits
Hartley’s or Decits.
𝑰 𝑲 = 𝐥𝐨𝐠 𝟏𝟎 𝟏(
𝟏
𝑷 𝑲
) Hartley’s or Decits
Nats or Neper.
𝑰 𝑲 = 𝐥𝐨𝐠 𝒆 𝟏(
𝟏
𝑷 𝑲
) Nats or Neper.
Extremal or Upper bound or Maximum entropy
𝑯(𝑺) 𝒎𝒂𝒙 = 𝐥𝐨𝐠 𝟐
𝒒 bits/message-symbol or 𝑯(𝑺) 𝒎𝒂𝒙 = 𝐥𝐨𝐠 𝟐
𝑵 bits/message-symbol.
Source efficiency
𝜼 𝑺=
𝑯(𝑺)
𝑯(𝑺) 𝒎𝒂𝒙
or 𝜼 𝑺=
𝑯(𝑺)
𝑯(𝑺) 𝒎𝒂𝒙
X 𝟏𝟎𝟎%
Source redundancy
𝑹 𝜼 𝑺
= 1- 𝜼 𝑺 = (1 -
𝑯(𝑺)
𝑯(𝑺) 𝒎𝒂𝒙
) X 𝟏𝟎𝟎%
The average information content of the symbols emitted from the i th state.
𝑯𝒊= 𝑷𝒊𝒋 𝐥𝐨𝐠 𝟐 𝟏 (
𝟏
𝑷𝒊𝒋
𝒏
𝒋=𝟏 ) bits/symbol or
𝑯𝒊= 𝑷𝒊𝒋 𝐥𝐨𝐠 𝒐 𝟏 (
𝟏
𝑷𝒊𝒋
𝒏
𝒋=𝟏 ) bits/symbol
The average information content of the symbols emitted from the k th state.
3. 𝑯 𝒌= 𝑷𝒍𝑲 𝐥𝐨𝐠 𝟐 𝟏 (
𝟏
𝑷𝒍𝑲
𝑴
𝒍=𝟏 ) bits/symbol
The average information content per symbol in a message of length N.
𝑮 𝑵=
𝟏
𝑵
𝑷(𝒊 𝒎𝒊)log
𝟏
𝑷(𝒎 𝒊)
or 𝑮 𝑵= −
𝟏
𝑵
𝑷(𝒊 𝒎𝒊)log P (𝒎𝒊) =
𝟏
𝑵
H ( 𝒔)
The entropy of the second order symbols.
𝑮 𝑵 =
𝟏
𝑵
H ( 𝒔 𝒙 𝑵
) where N=2.
The entropy of the third order symbols.
𝑮 𝑵 =
𝟏
𝑵
H ( 𝒔 𝒙 𝑵
) where N=3.
Log properties
1. 𝐥𝐨𝐠 𝒂 𝒃 =
𝟏
𝐥𝐨𝐠 𝒃 𝒂
𝟐.
𝐥𝐨𝐠 𝒙 𝒃
𝐥𝐨𝐠 𝒙 𝒂
= 𝐥𝐨𝐠 𝒂 𝒃
𝟑. 𝐥𝐨𝐠 𝒆 𝟏𝟎 = ln (10)