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Browse Prior Art Database

APPLICATION OF T-CODES TO FLEX SUITE MESSAGE ENCODING

IP.com Disclosure Number: IPCOM000009660D
Original Publication Date: 2000-Jan-01
Included in the Prior Art Database: 2002-Sep-09
Document File: 6 page(s) / 344K

Publishing Venue

Motorola

Related People

A. C. M. Fong: AUTHOR [+2]

Abstract

Packed HEX data converted from ASCII are currently used for encoding FLEX" Suite mes- sages. The author proposes the use of self-synchro- nizing T-codes for message encoding. Benefits include improved data integrity and coding efflcien- cy. Coding efficiency can be improved by 31% while automatic synchronization typically occurs within two characters following a lock loss. All these lead to improved fault tolerance.

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Technical MOTOROLA @ Developments

APPLICATION OF T-CODES TO FLEX'" SUITE MESSAGE ENCODING

by A. C. M. Fong and Cindy Quah

Huffman codes have been proposed by various researchers, one example is Ferguson and Rabinowitz2.

  More recently, Titchener has proposed a family of T-codes3 with encoding and decoding algorithms that have been shown to be a generalized family of self-synchronizing codes that are nearly optimally efficiency4. In this paper, the author investigates the application of T-codes to FLEXTM Suite message encoding.

  The motivation for this paper has already been discussed. The next section (II) gives a brief review of the current FLEXTM Suite message-encoding scheme. Section III gives a brief introduction to the family of T-codes. Possible application of the T- codes to FLEXTM Suite message encoding is given in section IV. That is followed by the concluding section (V).

FLEXTM SUITE PROTOCOLS-HIGHLIGHTS

  This section highlights the relevant aspects of the current FLEXTM Suite message scheme. Figure 1 shows the configuration of one example of the FLEXTM Suite of applications protocols: FLEXn" Information Service (FIQ5.

  The Status Information Field (SIF) is an S-bit header within FIS message and is followed by the data field. The SIF is used to identify the FLEX TM application protocol necessary for processing the remainder of the message. For example, the FIS has

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ABSTRACT

  Packed HEX data converted from ASCII are currently used for encoding FLEX" Suite mes- sages. The author proposes the use of self-synchro- nizing T-codes for message encoding. Benefits include improved data integrity and coding efflcien- cy. Coding efficiency can be improved by 31% while automatic synchronization typically occurs within two characters following a lock loss. All these lead to improved fault tolerance.

KEY WORDS

  Source coding, self-synchronizing codes, T- codes, paging protocols.

INTRODUCTION

  Block codes have traditionally been used to reduce uncertainty in synchronous data transmis- sion. In the event of a lock loss, the decoder can resynchronize when the next codeword length is found. This can be done easily because the code- word length is fixed.

  On the other hand, variable-length codes offer the opportunities for optimizing source-coding efl?- ciency if the statistics of the messages are known. Efficiency gains are achieved by assigning more fre- quently used symbols with shorter codewords and vice-versa. In other words, the probability of a sym- bol occurring should be a function of the inverse of the codeword length.

  It is well known that the Huffman algorithm' can be applied to obtain codes that are optimally efficient, achieving a coding entropy that is equal to or as close as possible to its corresponding source entropy. However, they do not generally show any promising sync performance. Self-synchronizing

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