RANAG-RadioAccessNetworkAggregator.ppt

8/14/2019 RANAG-RadioAccessNetworkAggregator.ppt

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Radio Access Network Aggregator (RANAG)

The Radio Access Network Aggregator (RANAG) is a transport network node, that may be used as ATMcross connect node or AAL2 switch for aggregation of RBS connections towards RNC.

The RANAG is a pure transport network node, that is, no Radio Network Layer functions are allocated to this node.

The only product supported in the role as a RANAG node is RXI 820 from Ericsson, which is based on the same platform asthe RNC and Node B and is supported by management applications in OSS Management platform.

In designing the first WCDMA RAN networks, typical site solutions include co-location of RNCs and Media Gate Ways. Thisimplies large “Iub -networks” where aggregation of RBSs can be done. The RANAG can provide such aggregation efficiently

through AAL2 switching, which allows for significant transmission gains from hub sites. Also, the addition of this independant node has been developed in response to specific requirements associated with a newgeneration of ATM and IP based wireless access networks.

The ATM aggregation and realtime IP routing features of the RANAG makes it ideal for deployment in wireless accessnetworks also allowing for a smooth migration from ATM to IP.

RANAG can be used as: – An ATM (VC cross connect) / AAL2 switching aggregator, or;

– A realtime IPv4/IPv6 router, or in future releases, as a combined ATM/AAL2 aggregator and realtime IPv4/IPv6 router



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Radio Access Network Aggregator (RANAG) ….continued

RANAG provides an efficient transport solution for delay sensitive traffic, such as voice and multimedia, carried on lowspeed links.

It is basically targeted for the wireless access network (RAN), where an excellent quality of service implementation,telecom grade reliability as well as synchronization of radio resource (Node B's) are examples of essential functions.

In the RANAG, real-time IP forwarding is implemented in hardware in order to support a high rate of packets persecond.

The RANAG also supports functionality for carrying TDM connections over ATM networks through circuit emulation.This allows service providers to carry legacy 2G and 3G traffic over the same network, which gives operationalsavings through the use of shared network resources.

ATM Functionality

ATM is the technology choice for initial deployment of WCDMA radio networks.

It provides an efficient packet data technology and built-in Quality-of-Service support which enables the network tocarry a combination of delay-sensitive traffic, such as voice, and best effort data traffic.

In addition to standard ATM VC cross-connect functionality, the RANAG supports AAL2 switching, which allows forfurther aggregation of ATM traffic and hence optimization of the radio access network transmission resources.

The RANAG has ATM and AAL2 switching functionality designed for use in Radio Access Networks. Different ATM Adaptation Layers are used for carrying circuit-emulated, voice and packet switched traffic: AAL1, AAL2 and AAL5,respectively.

RANAG also uses standard protocols for transport and signaling. The figure below shows an overview of the ATMsignaling and transmission services typically available in the RANAG



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RANAG Node B clusters aggregation

As mentioned before, A Node B Cluster is a group of Node B's with the following in common:

– The control and user plane traffic from all Node B's are aggregated into one ATM VP link or set of VP links or, forredundancy, one common pair of redundant ATM VP link or set of VP links towards northbound node. (Note: A set

of VP links is required in case of E1 links to northbound nodes.)

The aggregation is made by using VC CC or AAL2 switching.

– The reason for cluster aggregation is to achieve a better utilisation of the ATM VP links, i.e. to save ATM VP linkbandwidth.

– A second reason is to save VP, and on AAL2 multiplexer resources in the RNC and/or in intermediate aggregationnodes with AAL2 switching. The aggregation also allows all Node B's to use AAL2 path redundancy between thecluster anchor point and the RNC.



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RANAG Node B clusters aggregation …..continued

RANAG as VC Cross Connect

– The logical Iub interface can flexibly be mixed on the physical transport, RANAG supports, by means of VirtualCircuits (VC) cross connections, concentration of traffic from several RBSs to one physical link.

– The VC Cross Connect functionality in the RXI 820 can be used for setting up ATM Permanent Virtual Connections,(PVCs) between any port of any interface board in the RXI 820.

– The connections can be used to build a transport network structure on any supported transmission technology. VCCross Connect allows for an optimised ATM transmission network, with flexible placement of ATM aggregationpoints whilst complying to traffic contracts on limited bandwidth specified in 3GPP.



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ATM Functionality …..continued

RANAG as an AAL2 Switch

– RANAG also supports establishment of AAL2 connections through an ATM network using Q.263.1 signalingprotocol which is carried on AAL5.

– When a voice device produces a voice packet, with efficient silent time abstraction and compression, it can bemuch smaller than the ATM cell used for transport. Forwarding of one small packet inside a much bigger ATM cellwould waste a lot of bandwidth.

– Therefore ATM adaptation layer 2 (AAL2) is used for voice with routing control of the packets provided by Q.2630.1signaling. RANAG supports both these new technologies, in combination referred to as AAL2 switching, to providethe best possible ATM aggregation at hub sites.



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RNS topology -Physical view

Node B's can directly be connected to the RNC, or via user plane RANAG's. They can physically be connected tothe RNC according to the following topologies,

– Ring

– Tree

It is possible to configure the Iub interfaces with load sharing on parallel connections over two RANAG/Node Bnodes, where two such parallel nodes are available for increased fault tolerance and/or load sharing.

The generic RNS topology is illustrated in figure below:

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RANAG-RadioAccessNetworkAggregator.ppt