ALCAP ("Access Link Control Application Part") within a 3rd Generation

Universal Mobile Telecommunications System The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the Inte ...

(UMTS) network is the control plane

protocol Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

for the

transport layer In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end ...

Description

ALCAP is defined by 3GPP as equivalent of ITU recommendation Q.2630.2. Basic functionality of ALCAP is multiplexing of different users onto one

AAL2 ATM Adaptation Layer 2 (AAL2) is an Asynchronous Transfer Mode (ATM) adaptation layer, used primarily in telecommunications; for example, it is used for the Iu interfaces in the Universal Mobile Telecommunications System, and is also used for tran ...

transmission path using channel IDs (CIDs). It is used in the UMTS access network

UTRAN UTRAN (short for "UMTS Terrestrial Radio Access Network''") is a collective term for the network and equipment that connects mobile handsets to the public telephone network or the Internet. It contains the base stations, which are called Node B's ...

along with ATM, while IPBCP is use for IP links in the core of the network. ALCAP makes it possible for up to 248 channels to be multiplexed onto one AAL2 bearer.

Protocol stack

+----------------+
,  ALCAP          , 
+----------------+
,  SAAL           , 
+----------------+          
,  AAL5           , 
+----------------+
,  ATM     bø     , 
+----------------+
,  Physical layer , 
+----------------+

Access Link Control Application Part (ALCAP) ALCAP is the protocol used for control plane of transport layer UMTS in charge of managing and multiplexing users into ATM AAL2 virtual connections. ALCAP is specified for Iub, Iur and Iu (circuit switched domain) interfaces. This protocol is only used when these interfaces are ATM-based. The ITU-T Q.2630.2 standard, AAL type 2 signalling protocol - Capability Set 2, is chosen for ALCAP protocol. History For Iub and Iur interfaces, ALCAP is specified in 3GPP TS 25.426. For Iu interface, ALCAP is specified in 3GPP TS 25.414. Protocol dependencies * STC: Signalling Transport Converter SSCOP: the SAAL sublayer that transports ALCAP signaling messages. * SSCF-NNI, MTP3b: additional layers applicable only for Iur and Iu interfaces.

References

Transport layer protocols OSI protocols {{Telecomm-stub