4 General aspects
37.4603GPPIuant interface: General aspects and principlesRelease 17TS
The Iuant interface for the control of RET antennas or TMAs is a logical part of the RAN Node as shown for a Node B in figure 9 of TS 25.401  for UTRAN. Therefore, no new RAN element for the RET antennas or TMAs and no new RAN element manager is needed. The existing Implementation Specific O&M transport (see TS 25.442  for UMTS) is used for the connection between the RET antennas or TMAs control unit and the Node B element manager.
The Iuant interface between the Implementation Specific O&M function and the RET antenna control unit function is specified in detail in the specifications for layer 1, signalling transport and RET application part (TS 37.461 , TS 37.462 , TS 37.466 ).
4.2 Iuant interface general principles
The Iuant interface for the RET antenna control is based on a three-layer protocol model. The three-layer model is a compact form of the OSI seven-layer reference model and includes only layers 1, 2 and 7:
– The Physical Layer (Layer 1) defines the signalling levels and basic data characteristics including the data rates;
– The Data Link Layer (Layer 2) for the Signalling Transport uses a specific class of the HDLC standard as defined in ISO/IEC 13239 ;
– The Application Layer (Layer 7) defines the data payload format and the required command set. This layer is called the "Iuant: Application Part".
This compact model for the control interface provides an efficient protocol stack suitable for implementation on a single embedded micro-controller.
4.3 Iuant interface specification objectives
The Iuant interface specifications shall facilitate the following:
– Controlling the tilting of RET antennas remotely from the O&M Network and locally from the Node B;
– Indicating of TMA alarms and optionally controlling the gain of TMAs remotely from the O&M Network and locally from the Node B;
– Interfacing a mix of RET antennas, TMAs and RAN Node from different vendors;
– Providing RET or TMAs functionality accompanied by an appropriate set of signalling commands and control parameters;
– Support of error and alarm handling.
4.4 Iuant interface characteristics
The Iuant interface has a protocol structure as shown below in figure 4.4.1.
Figure 4.4.1: Protocol structure for Iuant interface
As the Iuant and the Implementation Specific O&M are different interfaces with e.g. different addressing schemes a mediation function is needed. This mediation function uses on one side a protocol that uses the implementation specific O&M bearer (e.g. IP) and on the other side the Iuant protocol.