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IMPROVEMENT TO CALCULATE CYCLIC REDUNDANCY BITS (CRC) IN A COMMUNICATION SYSTEM

IP.com Disclosure Number: IPCOM000009267D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-14
Document File: 2 page(s) / 76K

Publishing Venue

Motorola

Related People

Itzik Felman: AUTHOR [+3]

Abstract

This proposal in general relates to communica- tion interfaces, and, in particular to a parallel com- munication device used in communication systems operating in the Asynchronous Transfer Mode (ATM, e.g. 155Mbit/s or 622Mbit/s) and Ethernet (e.g., lOOMbit/s and lOOOMbit/s).

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Developments Technical 0 M MOTOROLA

IMPROVEMENT TO CALCULATE CYCLIC REbUNDANCY BITS (CRC) IN A COMMUNICATION SYSTEM

by ltzik Felman, Yoram Yeivin and Avi Shalev,

INTRODUCTION

  This proposal in general relates to communica- tion interfaces, and, in particular to a parallel com- munication device used in communication systems operating in the Asynchronous Transfer Mode (ATM, e.g. 155Mbit/s or 622Mbit/s) and Ethernet
(e.g., lOOMbit/s and lOOOMbit/s).

PROBLEM

In ATM, data is transferred in packages ("cells")
(e.g. 48 payload-bytes in each cell). For example, the transceiver simultaneously sends 2 bytes (2x8=16 bit) over 16 bit lines to the receiver. To ensure a high reliability of data transmission, the transmitter calculates CRC-bits (e.g., bits CRC-O
. ..CRC-31 simultaneously) according to predeter- mined standard schemes (e.g., CRC-32 like Ethernet, XOR-combinations (+) using data bits
(e.g., D-O...D-31) and previously calculated CRC- bits (e.g., C-O...C-31). Figure 1 illustrates a shift register having 32 delay units and xor-gates at pre- determined positions. The register receives D-0 to D-31 in parallel and consecutively provides the CRC-bits. The receiver uses a similar arrangement and can detect transmission errors by relating received data bit and CRC-bits.

  However, simultaneously calculating 32 CRC- bits requires a large amount of arithmetic units (not illustrated) and calculation time. For example, CRC-1 can be calculated according to:

(with k = 0...32, A e...