04.643GPPGeneral Packet Radio Service (GPRS)Mobile Station - Serving GPRS Support Node (MS-SGSN) Logical Link Control (LLC) layer specificationTS
For the purposes of the present document the following terms and definitions apply. Additional applicable definitions can be found in 3GPP TS 02.60 .
frame rejection condition: a condition that results from the receipt of an undefined or incorrect frame.
inquiry process: a process performed in the peer receiver busy condition in which the LLE checks that the peer LLE is still in the own receiver busy condition.
invalid frame condition: a condition that results from the receipt of an invalid frame.
logical link connection: the logical connection between two LLE peers. A logical link connection is identified with a Data Link Connection Identifier (DLCI). A logical link connection is always in one of three states: TLLI Unassigned, TLLI Assigned / ADM, or ABM.
logical link control layer: the protocol layer between an MS and an SGSN consisting of one or more logical link management entities, one or more logical link entities, and a multiplex procedure.
logical link entity: the LLC layer protocol state machine controlling one logical link connection.
own receiver busy condition: a condition that results from the inability to accept additional I frames from the peer logical link entity.
peer receiver busy condition: a condition that results from the reception in of a RNR frame from the peer logical link entity.
For the purposes of the present document, the following abbreviations apply. Additional applicable abbreviations and symbols can be found in 3GPP TS 01.04  and 3GPP TS 03.60.
ABM Asynchronous Balanced Mode
ADM Asynchronous Disconnected Mode
DM Disconnected Mode
FRMR FRaMe Reject
GMM GPRS Mobility Management
GRR GPRS Radio Resources service access point
IOV Input Offset Value
LAPD Link Access Procedure on the D-channel
LL Logical Link
LLC Logical Link Control
LLE Logical Link Entity
LLGMM LLC to GPRS Mobility Management service access point
LLM Logical Link Management
LLME Logical Link Management Entity
RNR Receive Not Ready
RR Receive Ready
SABM Set Asynchronous Balanced Mode
SACK Selective ACKnowledgement
TIA Telecommunications Industry Association
UA Unnumbered Acknowledgement
UI Unconfirmed Information
XID eXchange IDentification