RF receiver systems for W-CDMA technology
Estela Romero Muñoz · Theseus (Ammattikorkeakoulujen) · 2005
The evolution of mobile telecommunication services can be easily identified by the different mobile communication system generations.First generation systems consisted of analog networks offering solely speech oriented services.Second generation digital systems had the aim to develop a global system and pretended to offer supplementary services and several data oriented services in addition to the existing speech oriented services.The second generation has widely reached its purposes specially the European solution: GSM.An intermediate solution, known as 2.5 generation, was adopted in order to offer new data oriented services, due to the difficulties in the third generation launching.The purpose of the third generation was to offer a global standard.In order to attain this aim, the International Telecommunication Union (ITU) defined the International Mobile Telecommunication 2000 (IMT-2000).The main aims of this standard are:• Full coverage and mobility at 144 and 384 Kbps bit rates.• Limited coverage and mobility with bit rates down to 2 Mbps.• High spectral efficiency compared to existing systems.• Flexibility to introduce new services.• Possible use of a satellite component, in addition to the terrestrial component.In order to settle a global compatibility, the World Administrative Radio Conference (WARC) of the ITU, at its 1992 meeting, defined the operating frequency bands for third generation systems.Specifically, the bands comprised among 1885-2025 MHz and 2110-2200 MHz were assigned for third generation 4 RF Receiver Systems for W-CDMA technology systems.Assigned bands and spectrum allocation for the different regions can be observed in figure 1.1.Figure 1.1 Frequency allocations for IMT-2000 and UMTSHowever, due to the different proposals from the regional organizations, a global third generation system has been impossible to adopt.There are five different proposals for the air interface, grouped in four families, as can be seen in table 1.1. RF Receiver Systems for W-CDMA technologyThe CN is the basic platform for all the communication services that are provided for UMTS subscribers, including both telephony and packet-data services.The main elements in the CN are the same than in GSM/GPRS networks.• The Home Location Register (HLR) is a database located in the user's home system that stores the master copy of the user's service profile.The service profile consists of, for example, information on allowed services, forbidden roaming areas, and Supplementary Service information such a status of call forwarding and the call forwarding number.It is created when a new user subscribes to the system, and remains stored as long as the subscription is active.• The Mobile Services Switching Centre/Visitor Location Register (MSC/VLR) is the switch and the database that serves the UE in its current location for Circuit Switched (CS) services.The MSC function is used to switch the CS transactions, and the VLR function holds a copy of the visiting user's service profile, as well as more precise information on the UE's location within the serving system.The part of the network that is accessed via the MSC/VLR is often referred to as the CS domain.• The Gateway MSC (GMSC) is the switch at the point where UMTS PLMN is connected to external CS networks.All incoming and outgoing connections go through GMSC• The Serving GPRS Support Node (SGSN) has the same functionality as MSC/VLR but is typically used for Packet Switched (PS) services.The part of the network that is accessed via the SGSN is often referred to as the PS domain.• The Gateway GPRS Support Node (GGSN) has a similar functionality than GMSC but is related to PS services.