Title: 			Pre configuration of UTRAN Radio Access Bearer – Handover from GSM

Source: 		Ericsson,  Siemens,

Agenda Item: 	5

Purpose: 		Discussion

1	Introduction
The information needed for configuration of UTRAN radio bearer connections in case of handover from GSM to UMTS with a maximum of approximately 200 octets is not suitable for transportation in Handover To Utran Command due to the restriction on the air-interface.
The current assumption is that one segment shall be used over the radio-interface to transport the Handover To UTRAN Command. 
In order to reduce the number of octets needed to be sent in the handover command a reference pointer is sent in the handover command. The reference pointer will point to a set of attribute defining the radio bearer configuration needed for the handover.
A possible number of predefined sets are 16. Work is needed to define contents of the sets and the number of predefined sets. Each set will describe a specific bearer service.
To define the set it is proposed that a RR configuration command shall be used. Different options exists for this message in GSM. Based on configuration management in BSC, this message must be generated before the handover to UTRAN in order to build up tables in the mobile. The question  is when and how.

2	Solutions
The sets are service specific and probably not cell specific. This imply an solution where the service must be known before the configuration command can be issued. 

Solutions to be discussed;

•	BCCH would imply that all sets must be downloaded to the mobile.This would compete with other System Information messages and have some impact on measurement orders. The sets are downloaded unacknowledged.
•	SDCCH solution. At call set up signalling the configuration data is for example downloaded in CM SERVICE ACCEPT. Due to the amount of data and number of segments needed the call set up times would be prolonged considerable (approx. 2s).
•	Location update signalling.The same drawbacks as for the SDCCH solution and may additional prolong the Location updating procedure considerable due to the fact that all sets must be downloaded.
•	FACCH solution. L2 support for acknowledged transfer.The network has knowledge about which set to select and download.The drawbacks are service degradation of the connection before handover (TCH impact). 
•	SACCH solution. No L2 support for acknowledged transfer. No service degradation of TCH. Slow transfer and competing with measurement orders. The configuration data would be sent after the measurement order. Then everything would be periodically repeated to increase the possibility for correct reception.