ran 3g interfaces+protocols

8/6/2019 RAN 3G Interfaces+Protocols

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RAN 3G

� Interfaces� Protocols



Interfaces



Iub Functions

� Carrying information ± user voice, user data and cell-broadcast [UE

External networks]

± Radio resources control (RRC) signaling [UE RNC] ± NAS signaling (CC, SM, MM) [UE Core]� Node-B management

± Logical resources [NBAP]

± Physical resources [O&M]� Managing AAL2 links between RNC and Node-B[ALCAP (Q.2630)]



ProtocolsThe protocol architecture is divided horizontally into two key layers.

The upper part is referred to as the Radio Network Layer, and thelower is part is referred to as the Transport Network Layer. TheRadio Network Layer constitutes the source for data to betransferred across the interfaces; this data will be signaling or traffic.

The Transport Network Layer provides the necessary transportmechanisms, based on ATM.The protocol architecture is also divided into two planes, the control

plane and the user plane. The control plane handles controlinformation, pertaining to the radio interface. There are threeprotocols specified for the UTRAN:

� Node B application Part (NBAP) on the Iub interface� Radio Network Application Part (RANAP) on the Iu interface� Radio Network Subsystem Application Part (RNSAP) on the Iur

interface



Protocol Stack of the Iub Interface



Iub Protocol Stacks

Set VPI/VCI of NBAP and ALCAP



Iub procedures ± User traffic

� User voice and data information is carriedover the Dedicated and possibly theCommon Transport Channels.

� AMR is used on CS calls� PDCP and IP are used on PS calls



Iur functions� The Iur interface is the interface between two RNC¶s.� When a UE leaves the area controlled by an RNC to

another RNC, the UE¶s related data is now transferred tothe new RNC over the Iur interface.

� The original RNC is now referred to as Serving RNC andthe new RNC is now referred to as Drift RNC.

� Dedicated channels with the same characteristics areformed between the new DRNC to the relevant Node-B,

according to messages received on the Iur.� AAL2 decode is the same as Iub (same protocol stack)� AAL5 protocol stack is different



Main Iur Messages� Dedicated signaling channel

RNSAP: Radio Link Setup Request

RNSAP: Radio Link Setup Response ALCAP: Establish Request

� Dedicated traffic channelRNSAP: Radio Link Reconfiguration Request

RNSAP: Radio Link Reconfiguration Response ALCAP: Establish Request

� Channel DeletionRNSAP: Radio Link Setup Deletion



Iur Protocol Stack



NBAP

� Node B Application Part is a Layer-3 protocol atthe Iub interface. NBAP functions are dividedinto two groups, namely common and

dedicated NBAP procedures .� Common NBAP procedures are used to createnew user equipment (UE) contexts and controlBCCH broadcast information. The Iub always

contains one signalling link for the commonNBAP procedures, and there may be severalsignalling links for dedicated NBAP procedures.



RNSAP� The Iur interface procedures are controlled by the RNSAP signaling

protocol. Its function is to establish transport for the user planeframing protocols (soft handover

� = drift handover). The most important procedures are naturallyinvolved in:

� radio link set-up� radio link addition� radio link reconfiguration and� radio link deletion.

ran 3g interfaces+protocols

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