Browse Prior Art Database

PROGRAMMABLE GSM TRAFFIC DATA DEMULTIPLEXOR

IP.com Disclosure Number: IPCOM000007025D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2002-Feb-19
Document File: 2 page(s) / 91K

Publishing Venue

Motorola

Related People

Julian Singleton: AUTHOR [+3]

Abstract

In a system where subrate multiplexing is used for efficient data transfer, demultiplexing the data in a quick and flexible manner can be very complex and expensive. The GSM Digital Cellular System Transcoder to Channel Coder Interface provides an example where four 16kbit/s data timeslots are packed into a single 64kbit/s timeslot on a 2Mbit/s serial data stream for transfer between the Base Site Con- troller (BSC) and the Base Transceiver Station (BTS).

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MOTOROLA INC. Technical Developments Volume 20 October 1993

PROGRAMMABLE GSM TRAFFIC DATA DEMULTIPLEXOR

by Julian Singleton, Kevan Hobbis and Nigel Elliot

  In a system where subrate multiplexing is used for efficient data transfer, demultiplexing the data in a quick and flexible manner can be very complex and expensive. The GSM Digital Cellular System Transcoder to Channel Coder Interface provides an example where four 16kbit/s data timeslots are packed into a single 64kbit/s timeslot on a 2Mbit/s serial data stream for transfer between the Base Site Con- troller (BSC) and the Base Transceiver Station (BTS).

  In the present Motorola GSM Base Station Sys- tem, 64kbit/s timeslots (with four 16kbit/s embedded subchannels) on a CEPT 2.048Mbit/s serial stream are placed on an 8 bit parallel Time Division Multi- plex (TDM) bus from which the Channel Coder units remove 2 bits per TDM frame (125~~s).

  This system is a simple and cheap method of extracting eight, or more, 16kbit/s data channels from anywhere within a frame of thirty-two 64kbit/s timeslots, and passing each individual subchannel to a programmably selected processing unit. This system can also be used to extract eight, or more, Skbit/s data channels from the data stream as described above making it applicable for Half-Rate GSM Systems.

  Data flows into the circuit in CEPT 2.048Mbit/s format (see Figures 1 and 2). The received stream is fed into both the on-chip Programmable Strobe Gen- erator of the Motorola 68360 Microcontroller and the Bit-Selective Multiplexor. The MC68360 Core

Processor (CPU32) programs the Strobe Generator to generate...