Browse Prior Art Database

ENHANCED TRANSMISSION OF DATA OVER COMMON CHANNEL SIGNALLING NUMBER 7 LINKS

IP.com Disclosure Number: IPCOM000006721D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2002-Jan-25
Document File: 6 page(s) / 191K

Publishing Venue

Motorola

Related People

Vernon Fernandes: AUTHOR

Abstract

The transtnisrion of non time critical information over Common Channel SignaIling Number 7 (037) links behveen signaIling nodes is made more ejicient. The tech- nique exploits the unique combination of the need to send Operations and Maintenance (O&M) information over existing signalring links in a communications nehvork and the unused resource in the CCS7 protocol. An appliimtion example ti the link behveen the base station and switch in a GSM nehvork where the O&M centre communicates with the base via theswitch.

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MO-LA INC. Technical Developments Volume 17 December 1992

ENHANCED TRANSMISSION OF DATA OVER COMMON CHANNEL SIGNALLING NUMBER 7 LINKS

by Vernon Fernandes

ABSTRACT:

  The transtnisrion of non time critical information over Common Channel SignaIling Number 7 (037) links behveen signaIling nodes is made more ejicient. The tech- nique exploits the unique combination of the need to send Operations and Maintenance (O&M) information over existing signalring links in a communications nehvork and the unused resource in the CCS7 protocol. An appliimtion example ti the link behveen the base station and switch in a GSM nehvork where the O&M centre communicates with the base via theswitch.

1. INTRODUCTION:

  In systems employing common channel signalling number 7 (CCS7) the routing of messages through the network is handled by the Message Transfer Part (MTP) which is defined by CCIlT MTP transfers messages via signal units when needed. When no messages are to be transferred the message path is filled with dummy information. The invention proposes replacing dummy information with supplementary information or data (not connected with signalliig) that needs to be transferred two signalling transfer points (STP).

2. PRIOR ART

The signal units which are used to transport mes- sages in MTP fall in three categories [ 11 viz:

  Message Signal Unit (MS(I): Carries data for the higher level and identities the source and destination by means of point codes held within the signal unit.

Link Status Signal (LSSU): Carries control informa- tion such as alignment and out of service indication.

  fill In Signal Unit (FISU): Does not carry any infor- mation and is transmitted when no other signal units are transmitted.

See Figure 1 for the illustration. All signal units are

0 Motorola, Inc. 1992

carried over a signalling channel that is not physically part of a traflic channel. Traac channels are referred by addressing fields in the message units.

  In a GSM system the switch is connected to base stations over a 2048 kbit/s CEPT interface known as the A interface. The base and the switch can be consid- ered as STPs from a signalliig standpoint. At layer 1, information is transferred using the modulation scheme known as pulse code modulation (PCM) in which the transmitted bits are divided into time slots of 8 bits-see Fiie 2. Thirty two time slots are then grouped together to give a frame. Traffic is carried in one of 30 timeslots. Of the remaining two, one is used for synchronisation and the other for CCS7 messages. The CCS7 channel is capable of controlliig all the 30 traftic channels or the 120 channels obtained when transcoded (compressed) speech is used. Every active traf%c channel within the jurisdiction of the CCS7 channel will have associated with it a dedicated virtual CCS7 lii mapped on the 64 kbit/s channel. CCS7 links are differentiated by means of a signalling link code within the MSU. The lii is kept live by transmitting FISUs when there is no require- ment...