Liaison Statement to 3GPP SA2

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Chairman of ETSI Project Broadband Radio Access Networks

Jamshid Khun-Jush, Dr.-Ing.

Ericsson Eurolab Deutschland GmbH

Ericsson Research, Corporate Unit

Neumeyerstr. 50

D-90411 Nürnberg

Germany

Tel: +49 911 2551260 / Fax +49 911 2551961

Email:

Chairman of High Speed Wireless Access Committee of MMAC-PC

Masahiro Umehira, Dr.

Wireless Systems Innovation Laboratory

NTT Network Innovation Laboratories

Yokosuka

Japan

Tel: +81-468-59-3547 FAX: +81-468-55-1497

Email:

Chairman of IEEE 802.11

Stuart Kerry, Mr.

Philips Semiconductors

San Jose

USA

Tel: +148 408 474 7356 FAX: +148 408 474 7247

Email:

To: Puuskari MikkoDennis Eaton, Chairman of WiFi Alliance

Chairman 3GPP SA2

Date: 13th September0 3 May 2002

Subject: Liaison statement about new Wireless LAN Interworking Group (WIG)

Dear DennisPuuskari,

It is with great pleasure to inform you that MMAC HSWA, ETSI Project BRAN and IEEE 802.11 has jointly created a group to work on the issues related to 3G and other public access networks interworking. The group has been given the name WIG (Wireless LAN Interworking Group).

WIG has adopted the following scope:

- To be an integral part in the production of a generically applicable interworking standard for WWAN (Wireless Wide Area Network) and other public networks. The standard is to be applicable for IEEE 802.11 family, MMAC HiSWAN family and ETSI HIPERLAN/2

- To be the point of resolution for ETSI, IEEE and MMAC on issues related to interworking with WWAN and other public networks.

- To be the single point of contact for the above-mentioned WLAN standards on questions related to interworking with WWAN and other public networks.

The WLAN Interworking Group will deploy the two linked email reflectors given below that are available for subscription. The document areas will be open for members of IEEE, ETSI and MMAC only. If you are interested in these documents we then request information about how we can share relevant documents between our organisations.

Subscription can be made by sending an email to Mr. Al Petrick, apetrick@icefyre.com, identifying the following: Name, Title, Organization, Address, TEL, FAX, EMAIL and state the email reflectors name as above.

Subscription can be made via the "E-mail Archives - BRAN” window in the BRAN part of the ETSI portal http://portal.etsi.org/bran (click on the +/- icon to join the list) or by sending their request to

For additional information please make contact with one of the following persons below:

- Takashi Aramaki, , Liaison officer for the MMAC HSWA.

- TK Tan, , Chairman of the WNG SC at IEEE 802.11

- Thomas Haslestad, , Rapporteur of the 3G Interworking Group at ETSI Project BRAN.

Best Regards

Stuart Kerry, Jamshid Khun-Jush Masahiro Umehira

ETSI Project (EP) BRAN and MMAC HSWA committee have observed that you have now started a Work Item on WLAN interworking and would like to take this opportunity to present you with some more information about our ongoing work on WLAN – 3G and other Public Access networks interworking (standard on interworking). It is the intention of this liaison letter to specify in more details those areas within which we believe we can co-operate further.

Introduction

Since we have communicated with you previously, our two groups have progressed further along the path of creating a harmonised standard on interworking.

It is the intention of our groups to achieve the re-use of authentication procedures, accounting, mobility, QoS and other such fundamental functionalities between the two WLAN systems. Both BRAN and MMAC would like to propose a worldwide standard on interworking and we both feel that in order to achieve this goal, it is essential to invite 802.11 to participate with us in this activity.

Further more, it is our understanding that this will additionally assist 3GPP SA, by helping them in their ongoing work on 3G-WLAN interworking by the provision of a common interface. and to achieve this we feel that it is vital to present a unified position to them from the WLAN community.

Co-operation towards 3G and Public interworking

We achieved the decision above, by evaluating which groups can be seen to have an interest in our activity, as listed below:

• 3GPP SA1, 2, 3 and T2, T3

• IETF

and to reduce the complexity of this process, we foresaw that an unified position from the WLAN communities would be advantageous.

We appreciate that such a position may indeed have an impact on these involved groups, and this is indeed one of the reasons for this liaison at this point in time.

At this vital point in our common standardisation efforts we feel that feedback from IEEE 802.11 would assist us in making some important decisions.

The Definition of “W” Interfaces

To aid discussion within the rest of this document, it is necessary to define the following interfaces :

· “W.2” is the interface that represents the innermost interface within the scope of this standardisation activity. The defining of this interface requires co-operation between the system to the right and to the left of the W.2 in addition to co-operation with the standardisation body maintaining the protocols to be used.

· “W.3” is the interface that represents the external interface between the interworking functions and the external network and is out of scope of this standardisation activity.

Figure 1: Outline of reference architecture.

Areas ofReasons for co-operation

After careful consideration we have identified several principle areasreasons for co-operation:

· Agreement of scope between our organisations along a common interface W.2. An example of the usage of W.2 is the Ls interface would be used for the exchange of authentication messages between the WLAN network and interworked networks Local authentication function. Unified solution for 3GPP: As mentioned above in the introduction

· Unified positioning towards other relevant bodies e.g. IETF., 3GPP2, CEPT

· Co-operation at lower layers: increased commonality in implementation and impact on the

market, for example: roaming, interoperability.

· WLAN Public Access interworking global solution

Scope and Purpose of ETSI BRAN and MMAC HSWA standardisation

The scope of the present draft technical standard (DTS) is to provide the first release of the work towards the provisioning of a HIPERLAN/2 and HiSWANa interworking standard that is generically applicable to different 3G networks and other types of public access networks.

This first release (R1) is concerned with the establishment of functionality to provide a secure authentication scheme through the network to be interworked. Also R1 is concerned with the establishment of some basic functionality to allow for the provision of accounting and charging support. It further establishes an architectural baseline for the interworking concept and currently we do not have a specific deadline for this release.

The next stage (R2) is to provide the support for functionality such as service integration, mobility and QoS interworking differentiation support.

Figure 1 shows the current scope of different standardisation activities. It is felt that the mutual scope of our co-operation falls along the W.2 interface.

Figure 1: Scope of Standardisation

Figure 1 shows that position of common standards lies between the “W.2” interface and the “GAT” interface. This is regarded as the current scope of standardisation of our groups, essentially between the technology radio aspects of the systems and the service provider network.

The individual portions of Figure 1 are defined as follows:

· “System AAA”, identifies the outer boundaries of a system consisting of a WLAN access network interworking with a service provider network (i.e. 3G core net) for the provisioning of R1 functionality.

· “GAT” (Generic Authentication Transport Mechanism), described in a later paragraph, is an example of a technology specific adaptation layer.

Reference Architecture

The goal of the reference architecture is to focus on the functionality required in the Access Point Control (APC) Part and to specify the interface between the APC functions and the control functions within the interworking networkservice provider network (SPN). The reference architecture will also identify interfaces required within the Mobile Terminal (MT) and the information flows across them.

The following section provides an overview of the proposed reference architecture. It identifies the functions required within the network and the interfaces between them for R1.

Figure 2: Reference Architecture.

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Figure 2 : Reference Architecture

The Access Point (AP)/APC provides a logical grouping of the functions, but does not necessarily indicate the location of the function in terms of actual network implementations. The AP

The AP may be a single network node or it may be distributed function of many network nodes, and the reference architecture does not define any particular AP/APC implementation.

The reference architecture is shown in Figure 2. The terminology used in naming the different functions tries to follow IETF conventions where possible but does mandate the use of any particular transport infrastructure within the interworking networkSPN.

The interfaces are labeled as follows:

· L interfaces pass across the W.2 interface. These are the interfaces that are proposed for standardisation within the current scope of the reference architecture, excluding the Lr interface due to its dependence on the transport infrastructure of the interworking networkSPN. The L interfaces are required to run over a transport infrastructure that may vary depending on the scenario.

· M interfaces are internal interfaces within the MT. These interfaces are considered as reference points and are not proposed for standardisation, however specific reference to the interface Ms is made below.

· E interfaces pass across the W.3 interface. These interfaces are not proposed for standardisation within our organisations these would be the responsibility of the interworking network.the reference architecture, but will be referenced within the annexes of the DTS.

Within these categories of interfaces, the letters following the first letter indicate the type of function(s) the interface is used by.

The convention is as follows:

· a interfaces are used by accounting functions

· p interfaces are used by user policy control functions

· n interfaces are used by network policy control functions

· s interfaces are used by authentication mechanisms

Although many of the interfaces identified within the reference architecture will not be specified, it is useful to identify these interfaces in order to determine what information needs to be exchanged across the standardised interfaces.

It is necessary to have a common architecture for all WLAN systems and we feel that the above model presented in Figure 2 is a good working assumption. We invite you to also consider this as a possible model for IEEE 802.11 interworking with 3G and Public networks, for the functions defined in R1. The diagram within our previous liaison statement (BRAN25d130.doc) shows the functionalities and interfaces considered in future releases as well as R1.

Requirements

We would like to inform you that we have defined a set of system level requirements (ETSI TR 101 957 Ver. 1.1.1), specific to interworking and we invite you to review these, hopefully with the intention that they may also be applicable to future 3GPP SA2IEEE 802.11 needs. We would appreciate your feedback on these as to their applicability to 3GPP SA2IEEE 802.11.

We are currently in the process of mapping these requirements to the W.2 interface.

Authentication

Authentication provides a way to identify a user that wishes to access the HIPERLAN/2 or HiSWANa network and to authenticate the network with the user. The mechanism for authentication is typically undertaken through the exchange of logical keys or certificates between the MT and the AP. The AP may then forward this exchange towards the interworkingcore network for the purposes of centralised user administration. Authentication is supported by the Local Authenticator and the Attendant in the AP, and by the Authenticator in the MT.

It is currently proposed that the HIPERLAN/2 and HiSWANa RLC authentication procedure is changed to allow for a new procedure that is a generic transportation mechanism for authentication exchanges referred to as GAT. GAT hasthe possibility of carrying various authentication schemes and provides support for authentication scheme negotiation.

It is the current working assumption of the group that the authentication scheme iscarried by the GAT, is a new procedure based on EAP (the Extensible Authentication Protocol). This scheme has been dubbed "EAPOH" - EAP over HIPERLAN - by analogy with IEEE 802.1X EAPOL (EAP over LANs).

It is our opinion that the mechanisms for remote authentication concerningthe inter-working between theWLAN andinterworking networkSPN,, isare an area that would need to be common in order to achieve the aim of a single common view towards the 3GPP system and hence this is an area upon which we must cooperate in the interests of this attainment of this goal. The view taken by 3GPP SA2IEEE 802.11 on these matters would be most appreciated.

Accounting

We are additionally considering accounting and charging mechanisms within the scope of our work and would accordingly like to raise this to your attention. We would therefore value your opinion on the applicability of this work with respect to 3GPP SA2IEEE 802.11 and the proposed co-operation that we have detailed.