Advantages of a layered network architecture

Advantages of a layered network architectureUnlike GSM, UMTS is based on layered services. At the top is the services layer, which provides fast deployment of services and centralized location. In the middle is the control layer, which helps upgrading procedures and allows the capacity of the network to be dynamically allocated. At the bottom is the connectivity layer where any transmission technology can be used and the voice traffic will transfer over ATM/AAL2 or IP/RTP.

Mobile technologiesWhen converting a GSM network to a UMTS network, the first new technology is General Packet Radio Service (GPRS). It is the trigger to 3G services. The network connection is always on, so the subscriber is online all the time. From the operator's point of view, it is important that GPRS investments are re-used when going to UMTS. Also capitalizing on GPRS business experience is very important.From GPRS, operators could change the network directly to UMTS, or invest in an EDGE system. One advantage of EDGE over UMTS is that it requires no new licenses. The frequencies are also re-used and no new antennas are needed.

From GPRS to UMTSHome location register (HLR)Visitor location register (VLR)Equipment identity register (EIR)From GPRS network, the following network elements can be reused:Mobile switching centre (MSC) (vendor dependent)Authentication centre (AUC)Serving GPRS Support Node (SGSN) (vendor dependent)Gateway GPRS Support Node (GGSN)From Global Service for Mobile (GSM) communication radio network, the following elements cannot be reusedBase station controller (BSC)Base transceiver station (BTS)They can remain in the network and be used in dual network operation where 2G and 3G networks co-exist while network migration and new 3G terminals become available for use in the network.The UMTS network introduces new network elements that function as specified by 3GPP:Node-B (base station)Radio Network Controller (RNC)Media Gateway (MGW)The functionality of MSC and SGSN changes when going to UMTS. In a GSM system the MSC handles all the circuit switched operations like connecting A- and B-subscriber through the network. SGSN handles all the packet switched operations and transfers all the data in the network. In UMTS the Media gateway (MGW) take care of all data transfer in both circuit and packet switched networks. MSC and SGSN control MGW operations. The nodes are renamed to MSC-server and GSN-server.