04.643GPPGeneral Packet Radio Service (GPRS)Mobile Station - Serving GPRS Support Node (MS-SGSN) Logical Link Control (LLC) layer specificationTS

The state diagram representation of the peer-to-peer procedures is based on an expansion of the three basic states identified in subclause 4.5.2 to 7 states. An overview of the inter-relationship of these states is provided in Figure B.2.

An LLME and its LLEs are conceptually initiated in the TLLI Unassigned state (state 1). LLME interacts with GMM in order to be assigned a TLLI value. TLLI assignment causes LLME to transition to the TLLI Assigned state (state 2) and each of its LLEs to transition to the ADM state (state 2).

The receipt of an LL-ESTABLISH-REQ primitive by an LLE in the ADM state (state 2) causes the initiation of the local establishment procedure and the transition to the Local Establishment state (state 3). Completion of the establishment procedure takes the LLE to the ABM state (state 5).

Peer-initiated establishment causes a transition from the ADM state (state 2) to the Remote Establishment state (state 4). The receipt of an LL-ESTABLISH-RES primitive completes the establishment procedure and moves the LLE to the ABM state (state 5). In ABM state (state 5), LL-DATA-REQ primitives can be serviced directly subject to the restrictions of the procedures.

Expiry of timer T200, that is used in both the flow control and data transfer aspects of each LLE’s procedures initiates the transition to the Timer Recovery state (state 7). Completion of the timer recovery procedures returns the LLE to the ABM state (state 5). In states 5 and 7, the following conditions that are identified within the LLC specification are observed:

– peer receiver busy; and

– own receiver busy.

A peer-initiated release takes the LLE directly to the ADM state (state 2), whilst an LL-RELEASE-REQ returns the LLE state to the ADM state via the Local Release state (state 6).

TLLI Unassignment causes a transition to the TLLI Unassigned state (state 1) from any other state (states 2-7). Reset causes a transition to the TLLI Assigned / ADM state (state 2) from any other state except state 1.

In addition, all states should observe the suspended operation (reception of LLGMM-SUSPEND-REQ) restrictions, during which LLC frames may not be transmitted.

Figure B.2: Overview of the states of the peer-to-peer procedures

Annex C (informative):
Change History