Variable rate communication method and a variable rate communication system

• US 5,627,845 A
• Filed: 07/07/1994
• Issued: 05/06/1997
• Est. Priority Date: 07/16/1993
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kato, Osamu, Asano, Nobuo
• Primary Examiner(s): Gordon, Paul P.
• Assistant Examiner(s): OAKES, BRIAN
• Application Number:
  US08/271,668
• Time in Patent Office: 1,034 Days
• Field of Search: 371/43, 371/44, 371/45, 371/41, 375/1, 375/18, 375/37, 375/224, 375/225, 370/84, 341/61
• US Class Current: 714/795
• CPC Class Codes: H04B 2201/70705 Rate detection
• CPC Class Codes: H04J 3/22 in which the sources have different rates or codes simultaneous speech and digital data or video transmission H04M11/06; see provisional also H04J3/16
• CPC Class Codes: H04L 1/0046 Code rate detection or code type detection H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 25/0262 Arrangements for detecting the data rate of an incoming signal
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In variable bit rate communications in which the information rate changes at B/2ⁿ (where n is 0 or a positive integer) in each frame when the maximum information rate is B, at the transmitter side, information data is convolution coded in order to carry out an error correction of the information data, and when n≧1, coded data is repeatedly transmitted by (2ⁿ -1) times. At the receiver side, the information rate is detected from the transmission data that has been received, and when carrying out Viterbi decoding, an information rate is estimated by utilizing the repetition characteristics of the data, so that the coded data is Viterbi decoded for only the estimated bit rate, to thereby restrict an increase in the power consumption of mobile terminal units that are driven by batteries.

Claims

1. A variable rate communication method in which a transmitter transmits frames of transmission data and a receiver receives said transmission data, comprising the steps of:

in said transmitter,

performing convolution coding of the information data for error correction, an information rate of said information data in each frame being represented by any one of B, B/2, B/2², --B/2ⁿ, where B is a maximum information rate of said information data and n is 0 or a positive integer; and

generating said transmission data by repeating said convolution coded information data in each frame (2ⁿ -1) times when the information rate of said information data is B/2ⁿ, the number of times that said convolution coded information data is repeated in a given frame being a repetition number for that frame;

and, in said receiver,

determining the information rate of said information data from said received transmission data by finding the repetition number of said convolution coded information data, for every frame; and

after the information rate of said information data has been detected, performing Viterbi decoding of said received transmission data based on the detected information rate of said information data, for every frame.

2. A method according to claim 1, wherein said step of determining the information rate in said receiver comprises the steps of:

dividing said received transmission data into a plurality of data groups every frame, each data group including 2ⁿ units of data;

counting the number of units of data having a positive polarity and the number of units of data having a negative polarity, for every data group;

finding the absolute value of the difference between the counted number of units of data having the positive polarity and the counted number of units of data having the negative polarity, for every data group;

finding the average value of said absolute values, for every frame; and

estimating the repetition number in each frame based on said average value.

3. A variable rate communication system comprising:

a transmitter for transmitting frames of transmission data and a receiver for receiving said transmission data,

wherein said transmitter includes,

means for performing convolution coding of the information data for error correction, an information rate of said information data in each frame being represented by any one of B, B/2, B/2², --B/2ⁿ, where B is a maximum information rate of said information data and n is 0 or a positive integer; and

means for generating said transmission data by repeating said convolution coded information data in each frame (2ⁿ -1) times when the information rate of said information data is B/2ⁿ (n is 0 or a positive integer), the number of times that said convolution coded information data is repeated in a given frame being a repetition number for that frame;

wherein said receiver includes,

means for determining the information rate of said information data from said received transmission data, for every frame; and

means for performing Viterbi decoding of said received transmission data after said information rate of said information date has been determined, for every frame;

and wherein said determining means includes,

means for dividing said received transmission data into a plurality of data groups every frame, each data group including 2ⁿ units of data;

means for counting the number of units of data having a positive polarity and the number of units of data having a negative polarity, for every data group;

means for finding the absolute value of the difference between the counted number of units of data having the positive polarity and the counted number of units of data having the negative polarity, for every date group;

means for finding the average value of said absolute values, for every frame;

means for deciding a most likely repetition number by obtaining zero or a positive integer based on said average value, for every frame; and

means for finding the information rate of said information data based on said decided most likely repetition number, for every frame.

4. In a variable rate communications system in which a transmitter generates transmission data in frames by performing convolutional coding on information data and selectively repeating the convolutional coded information data based on a repetition number corresponding to a current information rate, the repetition number being zero or 2^n-1, where n is a positive integer, a receiver for receiving and decoding the transmission data comprising:

means for determining the repetition number of received transmission data for every frame, said means for determining including,

means for counting the number of received units of data having a positive polarity in each of a plurality of data groups,

means for counting the number of received units of data having a negative polarity in each of the data groups,

means for finding the absolute value of the difference between the number of received units of data having a positive polarity and the number of received units of data having a negative polarity in each of the data groups,

means for finding the average of the absolute values, and

means for estimating a most likely repetition number based on the average of the absolute values; and

Viterbi decoding means for performing viterbi decoding of the received transmission data at an information rate corresponding to the repetition number that has been estimated to be most likely.