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Introduction
There are several possible Network Reference Models (NRMs) that may guide the interworking between WiMAX and 3GPP. Both 3GPP and WiMAX end-end NRMs are capable of being the 'primary Broadband Network' with the other being an 'access network'. In other words, it is possible to have a deployment where a WiMAX enabled network offers policy control, authentication and service control to its subscribers and treat 3G as an 'access network' which will allow its 'WiMAX subscribers' to also have access to the same services when roaming over a 3G network. Flipping the coin, it is also possible for a 3G network to be the 'primary Broadband Network' with the WiMAX network serving as the access, in which case all policies, user admission and service policies are controlled by the 3G Network.
As it stands today, 3GPP,3GPP2 and IEEE Standard Development Organizations (SDOs) have made significant efforts in defining exhaustive standards upto Layer 3. The WiMAX forum, which has taken the task of defining an end-end WiMAX architecture (802.16 related groups in IEEE focussed more on PHY and MAC) is a much more recent activity from an SDO perspective. A lot of the focus of the NWG group within the WiMAX forum deals with L3 related issues and 'service level issues' are still undefined above L3, to a great extent.
On the other hand, 3GPP/2 SDOs have done exhaustive work in defining Stage 3 level operations (actual protocol flow) for handling service level decisions, routing, user profiles and policy control. Add to that the fact that there are over 70+ independant trials in final stage which also incorporate R6 IMS service/session control, it is our current belief that is is very likely that a model where '3G' is the primary network and WiMAX is the access network will be the first to be deployed.
Hence, for the time being, our NRM will assume that the operations of WiMAX will adhere to the 3GPP 22.934 I-WLAN model for generic access network interworking.
Note that when we discuss NRMs, there are two layers of interworking
a) 3GPP Core intetworking - which focuses on issues such as IP allocation, traffic tunneling, L2/L3 security
b) IMS interworking - which focusses on issues related to how the IMS network session control policies may interwork with a WiMAX network.
To that extent we present two NRMs titled WiMAX-3GPP NRM and WiMAX-IMS NRM. Both of these models derive from the WiMax? NWG Stage 2 architecture document. In the case of WiMAX-IMS NRM, we believe there are other interfaces and components which have not been identified in the NWG Stage 2 document which we have further highlighted.
Wimax-3GPP NRM (from NWG Stage-2 specifications)
Wimax-IMS NRM
- NOTE: This diagram is evolving. It may contain errors that will be resolved at a later stage of investigation. Also, this assumes that the CSN functionality is provided by the 3G Network. This includes IP address space allocation.
maintained by: arjun@hsc.com
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