TR <#> V 0.2.0 (<1999-06>)
Technical Report
3rd Generation Partnership Project (3GPP);
Technical Specification Group (TSG) CN;
Universal Mobile Telecommunications System (UMTS);
Separating RR and MM specific parts of the MS Classmark 

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1	
Table of Contents
1	Table of Contents	3
2	Intellectual Property Rights	5
3	Foreword	5
4	Introduction	5
5	Scope	5
6	References	5
7	Definitions and Abbreviations	5
7.1	Definitions	5
7.2	Abbreviations	5
8	Principle	6
9	Working Assumptions	6
10	Consideration of GSM	7
10.1.1	Parameter Structure	7
10.1.2	Notification Procedure	7
10.1.3	Paging Response Procedure	8
11	MS Classmark Restructuring	8
11.1	Parameter Structure	8
11.1.1	Separation of RAN and CN information	8
11.1.2	Limitation of length	8
11.1.3	Necessary Information	9
11.2	One Way Notification Procedure	9
11.3	Paging Response Message Protocol Category	9
11.3.1	Protocol Independence	10
11.3.2	MM Connection Setup Procedure	10
11.3.3	Modularity of Several Radio Systems	10
12	Compatibility to GSM	11
12.1	General Concept	11
12.2	Parameter Selection Rule	11
GSM	11
12.3	CM Service Invocation	11
12.3.1	Served by UMTS MSC	11
12.3.1.1	GSM BSS Area	11
12.3.1.2	UMTS RNC Area	12
12.3.2	Served by GSM MSC	13
12.3.2.1	GSM BSS Area	13
12.3.2.2	UMTS RNC Area	13
12.4	Handover from/to GSM	14
12.4.1	General Procedure	14
12.4.2	Handover to GSM	15
12.4.3	Handover from GSM	16
13	Modifications on Release 98	17

2	Intellectual Property Rights
[To be provided] 
3	Foreword
[To be provided] 
4	Introduction
[To be provided] 
5	Scope
[To be provided] 
6	References
[To be provided] 
7	Definitions and Abbreviations
7.1	Definitions
 [To be provided] 
7.2	Abbreviations
 [To be provided] 
8	Principle
UMTS MM protocol will be developed based on Release 98 of GSM04.08 incorporated new requirements from UMTS. This work needs to be done carefully with considering the balance of smooth migration from GSM and technical improvement.
Requirements in this TR mainly come from;
-	Concept of clear separation between Radio Access Network and Core Network
-	Improvement of signalling efficiency
Clear separation of radio access network technology and core network technology is one of prime requirement of UMTS. This concept enables the system to be developed independently from other sub-system technology. This causes easy evolution of the system applying suitable technology to the sub-system at the moment. Another advantage of the concept is that it achieves modularity of several radio system to UMTS core network. Depending on the environment, suitable radio access system can be different. The possible candidates are, for example, GSM RR, URAN, USRAN, BRAN, MMAC,..).
MM protocol is located upon Non-access stratum, which is a strata independent from access system technology. More clear separation than GSM is required.
In general, protocol seeks for the efficiency. This will be achieved as far as possible. 
9	Working Assumptions
Texts listed below are agreed working assumptions.
a)	Radio access network technology and core network technology should be clearly separated in principle so that MM protocol, which is for NC, should be radio independent.
b)	Mobile station capability related to RAN and CN need to be set in different parameters. Only CN related parameter should be present in MM message, and radio dependent information should not be included in MM messages.
c)	Two MS Classmark should be maintained both for UMTS and GSM. These are selectively used depending on the indication given by the CN.
d)	Not to define several MS classmark IE (e.g. for location updating, for CM service invoking, etc.) Same Mobile station classmark IE should be applied both for Location updating and CM service invocation considering the reuse of same RR connection
10	Consideration of GSM
10.1.1	Parameter Structure
Various information is packed in MS classmark in GSM, therefore location of RAN and CN information fields depend on each other. For the independent development of RAN and CN, it would be reasonable information for both sub-systems to be placed separately in different parameters. If they are packed in a parameter, interpretation of the information requires presumption of data structure of another sub-system(i.e., GSM CN and GSM RAN).
10.1.2	Notification Procedure
Paging Response message and CM Service Request message can carry only MS classmark 2 IE because of available length constraint, therefore further information such as MS classmark 3 IE should be got using Classmark Interrogation procedure. 
If another mobile station classmark is defined, it will not be included in neither of Paging Response message nor CM Service Request message but these parameters are retrieved by classmark interrogation procedure, which requires one more round trip at air interface. 
This procedure is because of a specific radio procedure applied to GSM. The procedure is that initial layer 3 information (i.e., CM Service Request message, Paging Response message ...) is sent on the UUI filed of SABM, which establishes layer 2 connection. This procedure is specific to GSM radio system. 
Some problems are seen in it. First one is that MM procedure is too much dependent on specific radio system procedure, and next is classmark interrogation procedure causes more radio traffic and delay of service provisioning to a user. 
10.1.3	Paging Response Procedure
Paging Response message is categorised in RR protocol and it is carried through A interface included in Complete Layer 3 Information message and then interpreted by MSC.
Issues identified are as follows,
a)	If Paging Response is carried though Iu interface to MSC, it needs to be analysed by MSC.  This means that MSC knows the format of RRC message. According to basic principle of UMTS, RAN and CN are to be independent from each other, therefore this procedure is against the principle.
b)	The modification to redefine Paging Response message in MM protocol does not have any impact to actual products of GSM MSCs, but the impact is just on the specification. 
c)	Issue of Paging Response categorisation is related to both RR and MM. If we are waiting for the simultaneous evolution both of RAN and CN, there is no chance to improve the protocol.
d)	We may have more than one radio systems for UMTS. These should be independent from each other in terms of protocol structure and so on, however both of which should commonly have same message, that is Paging Response message.
11	MS Classmark Restructuring
11.1	Parameter Structure
11.1.1	Separation of RAN and CN information
Considering the clear separation of radio access network and core network, mobile station classmark should be separately defined as new parameters.
Reason to have different MS classmark parameters for RAN and CN is that radio access network for UMTS is not necessarily one so that it is predicted to emerge more different systems. If we capture all the radio information in a same parameter, unnecessary information will increase endlessly. Considering the case, it would be a good approach to have different parameter by every radio system. 
MS classmark 2 IE and MS classmark 3 IE contains GSM RR specific information, which is not necessary for UMTS single mode terminal. So, these should not be included in MM protocol for UMTS.
MS Classmark for CN IE is to be defined in MM protocol and one for RAN is to be defined in RRC protocol. 
Mobile station classmark for each RAN will be independently defined in each system for the protocol independence and efficiency.
 [Editor’s note: Appropriate name for MS classmark for UMTS CN is requested.] 
11.1.2	Limitation of length
Mobile station classmark 3 IE has maximum length of IE, which is 14 octets. This is explained as because it is to fit in a single radio frame. 
As UMTS after the radio independent MM protocol, this limitation is desired to be put away. 
Layer 3 procedure should be designed to be independent from Layer 2 procedure. Procedure of Non-access stratum should be free from constraint of specific radio access network procedure. If we need to have limitation of length, this is to be determined as appropriate for MM protocol.
This limitation of length should be abolished.
11.1.3	Necessary Information
Newly defined MS classmark which is used in UMTS core network needs to be identified.
Information necessary for UMTS CN are listed below. The information is picked up from one in Mobile station classmark 2 IE and Mobile station classmark 3.  
[Editor’s note: Further check are required]
-	Revision level
-	SM capability
-	VBS notification Reception
-	VGCS notification Reception
-	UCS2
-	SS Screening Indicator
-	CM Service Prompt
11.2	One Way Notification Procedure
All the necessary information of UE should be sent in a message considering efficiency of radio resource and reduction of delay.
In UMTS, setup procedure of RRC connection and MM connection is clearly separated so that RRC connection has been established when initial non-access stratum message is sent. This procedure makes it possible to send more octets at the first message than it is in GSM so that the limitation of maximum number of the length is not so critical.

Figure 1 One Way Notification Procedure
11.3	Paging Response Message Protocol Category
As it seen in the following subclause, Paging Response message is categorized in RR protocol in current GSM specification, it is, however, acting like a MM message. Paging procedure in GSM is very well designed and basically there is no need to be modified. But only the classification of protocol of Paging Response message needs to be reconsidered.
Considering from philosophical viewpoint, Paging Response message should be MM protocol. 
The way paging procedure achieved in MM protocol needs further study. There are candidates below.
-	Define Paging Response message in MM
-	Add value representing paging response event in CM service type IE in CM Service Request message
11.3.1	Protocol Independence
If Page Response were to be an RRC message, it would be against the basic principle for protocol independence because Paging Response as RRC message is interpreted by MSC. If a part of RRC protocol entity is located in MSC, it is against the principle of clear separation of RAN and CN, and else if other protocol entity to RRC protocol can interpret and RRC message, it is against the principle of protocol independence. If Paging Response is defined in MM, there is no problem regarding this aspect. 
11.3.2	MM Connection Setup Procedure
As is CM Service Request, Paging Response is used as a trigger to establish MM connection. If we define Paging Response as an MM message, almost same procedure can be used both for originating call and terminating call. 
In current procedure, Paging Response is carried on Complete Layer 3 Information message, as CM Service Request is. Considering it, Paging Response has already acted like as MM message. There will be, therefore, no impact to current procedure.
11.3.3	Modularity of Several Radio Systems
We may have more than one radio systems for IMT-2000. These should be independent to each other, for example, in terms of protocol structure and other aspects. However both of which are forced to commonly have same message, that is Paging Response. In other words, Paging Response needs to be a radio system independent RRC message. It does not seem to be reasonable.
12	Compatibility to GSM
12.1	General Concept
It is very important to keep a harmonisation between compatibility issue and technical improvement when we consider the development of system. Evolution of MM protocol could be achieve to meet both requirements by defining new messages. 
The problem foreseen is that a UE cannot tell whether CN has a capability to accept new messages because capability of core network is not visible directly to UE. 
The CN broadcasts its type so that MS can select appropriate contents of MS Classmark parameter.
12.2	Parameter Selection Rule
Since messages are commonly used both for GSM and UMTS, contents of the MS Classmark IE needs to be selected according to the condition, which is described Table 1 below;
Table 1 Parameter Contents Selection Condition
RAN	CN	Selected Parameter	
GSM	GSM	MS Classmark 2	
GSM	UMTS	MS Classmark 2 *1	
UMTS	GSM	MS Classmark 2	
UMTS	UMTS	MS Classmark for UMTS	
*1: MS Classmark 2 may be converted to MS Classmark for UMTS by IWF.
12.3	CM Service Invocation
12.3.1	Served by UMTS MSC
12.3.1.1	GSM BSS Area
CM service invocation procedure under GSM-BSS and UMTS-MSC is shown in Figure 2.

Figure 2 CM Service Invocation under BSS
Procedure: 
0.	The MS detects that it is under GSM BSS area and served by UMTS MSC at the moment by broadcast information
1.	The MS sends CM Service Request message to MSC via BSS with MS Classmark 2 IE. BSS memorize the MS Classmark 2 at the relay process.
2.	If the MSC determines that further MS classmark is necessary, classmark interrogation procedure is invoked.
3.	Receiving the Classmark Request message from MSC, BSS send Classmark Enquiry message to get MS classmark from MS.
4.	Receiving the Classmark Enquiry message from BSS, MS send back MS Classmark 2 and 3 to BSS.
5.	BSS memorize the received MS Classmark 2 IE and MS Classmark 3 IE and relays them to MSC by Classmark Update message. MSC get all the necessary MS capability information.
12.3.1.2	UMTS RNC Area
CM service invocation procedure under UMTS-RNC and UMTS MSC is shown in Figure 4.

Figure 4 CM Service Invocation under RNC
Procedure: 
0.	The UE detects that it is under UTRAN area and served by UMTS MSC at the moment by broadcast information.
1.	The UE starts RRC connection setup procedure, and during the procedure MS Classmark for RAN is sent to RNC.
2.	After the establishment of the RRC connection, The UE sends CM Service Request message to the MSC with MS Classmark for CN IE.
12.3.2	Served by GSM MSC
12.3.2.1	GSM BSS Area
CM service invocation procedure under GSM-BSS and GSM-MSC is shown in Figure 6.

Figure 6 CM Service Invocation under BSS
Procedure: 
0.	The MS detects that it is under GSM BSS area and served by GSM MSC at the moment by broadcast information
1.	The MS sends CM Service Request message to MSC via BSS with MS Classmark 2 IE. BSS memorize the MS Classmark 2 at the relay process.
2.	If the MSC determines that further MS classmark is necessary, classmark interrogation procedure is invoked.
3.	Receiving the Classmark Request message from MSC, BSS send Classmark Enquiry message to get MS classmark from MS.
4.	Receiving the Classmark Enquiry message from BSS, MS send back MS Classmark 2 and 3 to BSS.
5.	BSS memorize the received MS Classmark 2 IE and MS Classmark 3 IE and relays them to MSC by Classmark Update message. MSC get all the necessary MS capability information.
12.3.2.2	UMTS RNC Area
CM service invocation procedure under UMTS-RNC and GSM MSC is shown in Figure 7.

Figure 7 CM Service Invocation under RNC
Procedure: 
0.	The UE detects that it is under UTRAN area and served by UMTS MSC at the moment by broadcast information.
1.	The UE starts RRC connection setup procedure, and during the procedure MS Classmark for RAN is sent to RNC.
2.	After the establishment of the RRC connection, The MS sends CM Service Request message to MSC via RNC with MS Classmark 2 IE. RNC transparently relays the message.
3.	If the MSC determines that more MS classmark is necessary, classmark interrogation procedure is invoked. 
4.	Receiving the Classmark Request message from MSC, RNC send Classmark Enquiry message to get MS classmark from MS. *1
5.	Receiving the Classmark Enquiry message from RNC, MS send back MS Classmark 2 and 3 to the RNC. 
6.	RNC transparently relays the received MS Classmark 2 IE and MS Classmark 3 IE to MSC by Classmark Update message. MSC get all the necessary MS capability information. 
*1: Classmark Request message from MSC may be replaced into appropriate message by IWF between GSM MSC and UMTS RNC. Further study is needed.
12.4	Handover from/to GSM
12.4.1	General Procedure
UMTS is an evolved from GSM, however both system are different so that information for both system should be in different parameters. UMTS single mode terminal does not need GSM information. Considering the efficiency it is better not to include Mobile station classmark for GSM (i.e., MS classmark 2) in initial layer 3 message for UMTS. 
This is based on an assumption that procedure below is applied in case of inter radio system handover (including to/from GSM BSS). 
Assumption: Procedure which appears in Iu interface in case of inter radio system HO is same as one of inter BSS HO of GSM. [Note: This assumption needs to be confirmed] 
-	MS Classmark for CN is transferred to CN in CM service invocation procedure (e.g. CM Service Request, Paging Response etc.) and it is not influenced by handover. 
-	MT notifies all the supporting radio information to RNC in RRC connection setup procedure.
-	MS Classmark for RANs is transferred to target RAN in inter radio system HO procedure through Iu.
-	The detail condition which classmark to be transferred needs to be studied because it would depend on the direction of handover (i.e., one directional or both directional)

Figure 8 Iu Procedure for Inter Radio System Handover
MS classmark for RAN A or B can be Mobile station classmark 2 and 3. 
If this approach is applied, radio information does not need to be sent to CN together with core network information in MS Classmark for CN. As a conclusion, MS capability information for radio access network does not need to be included in MM message. 
It can be a case that core network supporting capability would be different depending on the radio access system which is serving the mobile terminal. Considering this case, classmark interrogation procedure might be invoked in case of inter radio system handover. This issue needs further study.
12.4.2	Handover to GSM
CM service invocation procedure under UMTS-RNC area is shown in Figure 9.

Figure 9 Handover from UMTS to GSM
In this case, BSS does not requires any new capability at least MS classmark restructuring point of view.
12.4.3	Handover from GSM
Handover procedure from GSM to UMTS is shown in Figure 11.

Figure 11 Handover from GSM to UMTS
In this case, BSS requires small additional capability to handle MS Classmark for RAN. Note that other capability than regarding MS Classmark will be also needed.