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Content for  TS 44.064  Word version:  18.0.0

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1  Scopep. 8

The present document defines the Logical Link Control (LLC) layer protocol to be used for packet data transfer between the Mobile Station (MS) and Serving GPRS Support Node (SGSN).
It defines the frame structure, elements of procedure, format of fields, and procedures for the proper operation of the logical link control layer. It is based on ideas contained in IS-130 [21], ISO 3309 [16], ISO 4335 [17], and ISO 7809 [18] [19] [20] (HDLC of ISO), as well ITU-T Q.920 [13] and Q.921 [14] (LAPD). The concepts, the overview description of LLC layer functions and procedures, and the relationship with other Technical Specifications are described in general terms in TS 23.060.
LLC spans from the Mobile Station (MS) to the Serving GPRS Support Node (SGSN). LLC is intended for use with both acknowledged and unacknowledged data transfer.
The frame formats defined for LLC are based on those defined for LAPD and RLP. However, there are important differences between LLC and other protocols, in particular with regard to frame delimitation methods and transparency mechanisms. These differences are necessary for independence from the radio path.
The LLC procedures are modelled upon the concepts of HDLC as outlined in ISO 4335. Data sequence integrity between the data source and data sink is effected by means of a cyclic numbering scheme. An independent numbering scheme is used for each logical data link, as identified by the a data link connection identifier. LLC supports two modes of operation:
  • Unacknowledged peer-to-peer operation:
    A logical link entity may initiate transmissions to a peer entity without prior establishment of a logical connection with the peer entity. LLC does not guarantee in-order delivery. LLC can detect errors in a received frame, and, depending on whether the frame is sent in protected mode or not, either discard or deliver the erroneous frame. No error recovery procedures are defined at the LLC layer. Higher-layer protocols can be used to provide reliability, if needed. This mode of operation is known as Asynchronous Disconnected Mode (ADM).
  • Acknowledged peer-to-peer operation:
    A balanced data link involves two participating entities, and each entity assumes responsibility for the organisation of its data flow and for error recovery procedures associated with the transmissions that it originates. Each entity operates as both a data source and data sink in a balanced link, allowing information to flow in both directions. This mode of operation is known as Asynchronous Balanced Mode (ABM), and provides a reliable service with in-order delivery.
In unacknowledged operation, LLC can provide integrity protection.
The present document is organised as follows:
  • An overview of the LLC layer functions is given in clause 4.
  • The frame structure for peer-to-peer communication is given in clause 5.
  • The elements of procedure and formats of fields are given in clause 6.
  • The elements of layer-to-layer communication are contained in clause 7.
  • The details of the peer-to-peer ABM procedures are given in clause 8.
  • The details of LLC frame ciphering are given in Annex A.
  • The details of the TOM protocol layer are contained in Annex B.
  • An overview of the LLC layer states is provided in Annex C.
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2  Referencesp. 9

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
[1]
TR 21.905: "Vocabulary for 3GPP Specifications".
[2]
TS 41.061: "General Packet Radio Service (GPRS); GPRS ciphering algorithm requirements".
[3]
TS 22.060: "General Packet Radio Service (GPRS); Service description; Stage 1".
[3a]
TS 23.003: "Numbering, addressing and identification".
[4]
TS 23.040: "Technical realization of the Short Message Service (SMS); Point-to-Point (PP)".
[5]
TS 23.060: "General Packet Radio Service (GPRS); Service description; Stage 2".
[5a]
TS 23.251: "Network Sharing; Architecture and Functional Description".
[6]
TS 43.064: "General Packet Radio Service (GPRS); Overall description of the GPRS radio interface; Stage 2".
[7]
TS 44.001: "Mobile Station Base Station System (MS BSS) interface; General aspects and principles".
[8]
TS 44.018: "Mobile radio interface; Layer 3 specification; Radio Resource Control Protocol".
[8a]
TS 24.008: "Mobile radio interface layer 3 specification; Core Network Protocols; Stage 3".
[9]
TS 24.011: "Point-to-Point (PP) Short Message Service (SMS) support on mobile radio interface".
[10]
TS 24.022: "Radio Link Protocol (RLP) for circuit switched bearer and teleservices".
[11]
TS 44.065: "General Packet Radio Service (GPRS); Mobile Station (MS) - Serving GPRS Support Node (SGSN); Subnetwork Dependent Convergence Protocol (SNDCP)".
[12]
TS 48.018: "General Packet Radio Service (GPRS); Base Station System (BSS) Serving GPRS Support Node (SGSN); BSS GPRS Protocol (BSSGP)".
[13]
ITU-T Recommendation Q.920 (1988): "ISDN user-network interface data link layer - General aspects".
[14]
ITU-T Recommendation Q.921 (1988): "ISDN user-network interface - Data link layer specification".
[15]
ITU-T Recommendation Z.100 (1988): "CCITT specification and description language (SDL)".
[16]
ISO 3309 (1984): "Information processing systems - Data communications - High-level data link control procedure - Frame structure".
[17]
ISO 4335 (1987): "Information processing systems - Data communication - High-level logical link control procedures - Consolidation of elements of procedures".
[18]
ISO 7809 (1984): "Information processing systems - Data communication - High-level logical link control procedures - Consolidation of classes of procedures".
[19]
ISO 7809 (1984): "Information processing systems - Data communication Add. 1: 1987 - High-level logical link control procedures - Consolidation of classes of procedures - Addendum 1".
[20]
ISO 7809 (1984): "Information processing systems - Data communication Add. 2: 1987 - High-level logical link control procedures - Consolidation of classes of procedures - Addendum 2: Description of optional functions".
[21]
TIA IS-130 (1995): "800 MHz Cellular System - TDMA Radio Interface - Radio Link Protocol 1" Arlington: Telecommunications Industry Association.
[22]
TIA/EIA 136 (1999): "TDMA Cellular / PCS"; Arlington: Telecommunications Industry Association.
[23]
TS 44.060: "General Packet Radio Service (GPRS); Mobile Station (MS) - Base Station System (BSS) interface; Radio Link Control/Medium Access Control (RLC/MAC) protocol".
[23a]
TS 29.018: "General Packet Radio Service (GPRS); Serving GPRS Support Node (SGSN) - Visitors Location Register (VLR); Gs interface layer 3 specification".
[24]
TS 44.031: "Mobile Station (MS) - Serving Mobile Location Centre (SMLC) Radio Resource LCS Protocol (RRLP)".
[25]
TS 43.059: "Functional Stage 2 Description of Location Services (LCS) in GERAN".
[26]
TS 43.129: "Packet-switched handover for GERAN A/Gb mode; Stage 2".
[27]
TS 43.020: "Security-related network functions"
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3  Definitions and abbreviationsp. 10

3.1  Definitionsp. 10

For the purposes of the present document, the terms and definitions given in TS 21.905 and TS 22.060 and the following apply:
active LLE:
an LLE which SAPI is assigned to a layer 3 entity.
empty XID command:
an XID command sent by the SGSN which does not contain parameters to negotiate.
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 terms and definitions given in TS 23.251 apply:
Multi-Operator Core Network
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3.2  Abbreviationsp. 11

For the purposes of the present document, the abbreviations given in TR 21.905 and TS 23.060, and the following apply:
ABM
Asynchronous Balanced Mode
ACK
ACKnowledgement
ADM
Asynchronous Disconnected Mode
CNF
CoNFirm
DISC
DISConnect
DM
Disconnected Mode
FCS field
Frame Check Sequence field
FRMR
FRaMe Reject
GMM
GPRS Mobility Management
GRR
GPRS Radio Resources service access point
I
Information
IND
INDication
IOV
Input Offset Value
Kc
64-bit ciphering key
Kc128
128-bit ciphering key
LAPD
Link Access Procedure on the D-channel
LCS
Location Services
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
MAC layer
Medium Access Control layer
MAC field
Message Authentication Code field
MOCN
Multi-Operator Core Network
REQ
REQuest
RES
RESponse
RLC layer
Radio Link Control layer
RNR
Receive Not Ready
RR
Receive Ready
RRLP
Radio Resource LCS Protocol
S
Supervisory
SABM
Set Asynchronous Balanced Mode
SACK
Selective ACKnowledgement
TIA
Telecommunications Industry Association
TOM
Tunnelling Of Messages
UA
Unnumbered Acknowledgement
UI
Unconfirmed Information
XID
eXchange IDentification
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