Umts explained
- 1. UMTS(Universal Mobile Telecommucation System) Overview FeaturesHigh quality Speech ( Wideband speech) – A new wideband AMR (Adaptive Multi-Rate) codec to increase the quality of speech over UMTS. High Speed Packet Access – With HSDPA (high speed downlink packet access) and HSUPA (high speed uplink packet access) a peak data rate of 10.2Mbit/sec in the download direction. Further improvements to the radio network and user devices will be able to offer user peak rates in the download direction of 3.6Mbit/sec. Handover to GSM/GPRS – Voice calls and data traffic can be transferred between GSM and UMTS seamlessly. Multimedia Messaging Service (MMS) – It allows the transfer of multimedia messages between users without the requirement for the multimedia messages to be transferred in real-time. Multimedia Telephony for IMS – This uses IMS to offer telephony services such as video, text, picture sharing, video clip sharing etc. IP-based multimedia core network subsystem (IMS) – This provides support for IP multimedia sessions in a flexible manner to allow new multimedia products and services to be offered. The IMS can use both the GPRS and UMTS radio access technologies. Operation in other frequency bands - In addition to the 2GHz band, UMTS can also operate in the 810MHz; 900MHz; 1700MHz and 2.6GHz bands. End to end Quality of Service – Quality of Service management for the Packet Switched (PS) domain including the IMS and the radio interface. MBMS (Multimedia Broadcast Multicast Service) – This allows information such as streamed audio and video to be sent over one radio channel to many customers simultaneously. Wireless LAN inter-working – This allows connection to the core network using WLAN as well as the usual GSM/UMTS radio access. Network Selection– Network operators/users can select best network for their needs while roaming.
- 2. Major UMTS Components The UMTS Release 99 architecture is composed of three components- User Equipment (UE) : UMTS mobile station can operate simultaneously in both Packet Switched (PS)/Circuit Switched (CS) mode or only any one of them. It is composed of Universal Subscriber Identity Module-card (USIMcard), the radio equipment (receiver-transceiver), the Man-Machine Interface (MMI) (support for multimedia, WAP, and other services) and Battery. UMTS Terrestrial Radio Access Network (UTRAN) : UMTS radio access infrastructure is called UTRAN. It uses Wideband Code Division Multiple Access (WCDMA ) radio technology for air interface to communicate with UE. Core Network (CN) : It provide switching, routing and transit for user traffic. It also contains the databases and network management functions.
- 3. Major Components Core Network is split into the following domains: CS (Circuit Switch) domain It uses 64 kbps Time Division Multiplexed (TDM) channels. This domain provides a similar set of services as those provided by GSM. It uses Iu-CS interface as A interface in GSM. PS (packet switch) domain The PS domain is based on GPRS, with substitution of the Iu-PS interface for the Gb interface.
- 4. UTRAN overview It is composed of one or more RNS connected to core network through IuCS/IuPS interface. UMTS Core Network (UCN) IuCS UTRAN IuPS RANAP RANAP RNS RNC Iub Node B RNS RNSAP Iur (logical connection) RNC Iub Iub Node B cell cell Iub Node B cell Node B cell Uu Uu UE UE
- 5. UTRAN Components Node B A Node B is responsible for radio transmission/reception in one or more cells to/from the user equipment. It can support Frequency Division Duplex (FDD) mode, Time Division Duplex (TDD) mode or dual-mode operation. It provides the following interfaces • Iub interface towards the UMTS RNC • Uu interface towards the UE RNC The RNC is the central element in the UTRAN. It’s main function is to control and manage the RAN(Radio Access Network) and the radio channels. For each connection between a UE and the UTRAN, there is one serving RNS. A drift RNS supports the serving RNS by providing radio resources.
- 6. UTRAN Functionalities The UTRAN provides the following functions: • Transfer of user data Provides user data transfer capability across the UTRAN between the Iu and Uu reference points. • Radio channel ciphering and deciphering Provides Ciphering and deciphering services for radio channel sessiondependent key, derived through signaling and/or session dependent information. • Services related to Broadcast and Multicast traffic Provides Broadcast and Multicast Information distribution and flow control • CBS status reporting RNC collects status data per cell (No-of-Broadcast-Completed-List, RadioResource-Loading-List) and provides to CBC if requested. • Data volume reporting - reports the volume of unacknowledged data to the CN for accounting purpose.
- 7. UTRAN Functionalities • Functions related to overall system access control Admission control The purpose of the admission control is to admit or deny new users, new radio access bearers or new radio links. Congestion control The task of congestion control is to monitor, detect and handle situations when the system is reaching a near overload or an overload situation with the already connected users. System information broadcasting This function provides the mobile station with the Access Stratum and Non-Access Stratum information. The basic control and synchronization of this function is done in UTRAN.
- 8. UTRAN Functionalities • Functions related to mobility Handover This function is based on radio measurements. It manages the mobility of the radio interface and maintains the Quality of Service(QOS) negotiated between the UE and the CN. SRNS Relocation The SRNS relocation function coordinates the activities when the SRNS role is to be taken over by another RNS. Paging support This function provides the Core Network with the ability to contact the UE when it is in the PLMN_IDLE state Positioning This function provides the capability to determine the geographic position of a UE.
- 9. UTRAN Functionalities • Functions related to radio resource management and control Radio resource management is concerned with the allocation and maintenance of radio communication resources. Radio resource configuration and operation It configures the radio network resources (cells ,transport channels) Radio environment survey It performs measurements on radio channels. combining/splitting control It controls the combining/splitting of information streams through cells connection set-up and release It is responsible for the control of connection element set-up and release. Allocation and deallocation of radio bearers It translates the connection element set-up or release requests into physical radio channel allocation or deallocation.
- 10. UTRAN Functionalities RF power control This group of functions controls the level of the transmitted power to minimize interference and keep the quality of the connections. Radio channel coding It provides functions for detection or correction of signal errors introduced by the transmission medium. Radio channel decoding It provides channel coding function to detect or correct possible errors in the received data flow. Initial (random) access detection and handling It provides functions that has the ability to detect an initial access attempt from a mobile station and respond appropriately.
- 11. CoreNetwork Overview It provides functions that has the ability to detect an initial access attempt from a mobile station and respond appropriately. The UMTS Core Network is split into a circuit-switched (CS) domain and a packet-switched (PS) domain CCN : The circuit-switched domain of the UMTS PLMN is called the Circuit Core Network (CCN). The CCN performs the main circuit switching functions and manages the following: • communication among UMTS UE • communication between UMTS UE and users in other networks Major circuit-switched components • Transcoder and Rate Adaptation Unit (TRAU) • Mobile Switching Center (MSC) • Home Location Register (HLR)
- 12. CoreNetwork Overview TRAU The TRAU is a device that takes UMTS speech packets as input and it converts them into standard ISDN 64 kbps speech flow. MSC The MSC is responsible for circuit domain call processing and circuitswitched data. It coordinates the setup of calls to and from all UMTS subscribers operating in its area. It controls the paging function (incoming calls) and performs ticketing on calls for all subscribers based in its area. The MSC transfers encryption parameters from Visitor Location Registers (VLR) to the UTRAN to enable ciphering on the radio interface. HLR It is a network database used for permanent management of mobile subscribers within a PLMN. It is accessible from the 3G-SGSN and the MSC.
- 13. CoreNetwork Overview Packet-switched domain The packet-switched domain contains the following major components: • 3G-Serving GPRS Support Node (3G-SGSN) • Gateway GPRS Support Node (GGSN) 3G-SGSN The 3G-SGSN requests location information from the HLR through the Gr interface. It performs setup and routing of data sessions. GGSN provides the point of interconnection with external Packet Data Networks (PDN) for Public Land Mobile Networks (PLMN) supporting UMTS. This interconnection utilizes the Gi interface. The GGSN stores routing information for attached UMTS users. The routing information is used to tunnel Protocol Data Units (PDU) to the current 3G-SGSN serving the MS(UE).
- 14. CoreNetwork Overview Other Core Network elements VLR (Visitor Location Register) The VLR contains all subscriber data required for call handling for the mobile subscribers currently located in the area controlled by it. AuC (Authentication Center) It is a database that contains secret subscriber keys and security algorithms. It generates security information for authentication and ciphering. EIR (Equipment Identity Register) It is a database that stores IMEIs used within a GSM or UMTS network. Additionally, the register may store the status of said IMEI (classified as "white listed", "gray listed" or "black listed"). SMS Gateway MSC It acts as an interface between a Short Message Service Center and the PLMN. Short messages can so be delivered to mobile stations from the Service Center (SC). SMS Interworking MSC It acts as an interface between a Short Message Service Center and the PLMN. IWF (Interworking Function) It provides the functionality necessary for interworking between a PLMN and the fixed networks (ISDN, PSTN and PDNs). DNS (Domain Name Service) Server It translates between Fully Qualified Domain Names and IP address. It translates the Access Point Names requested by the subscribers to the IP address of the access point. DHCP (Dynamic Host Configuration Protocol ) Server It assigns IP addresses as required.
- 15. Protocols Uu – Air interface between a nodeB and UE. Iub -Interface between an RNC and its nodeBs. Iur - Interface between two RNCs support specific functions such as handover. Iupc - Interface between an RNC and a SAS (Stand-alone A-GPS SMLC) within the UTRAN. Iu-CS - Circuit switched variant of the Iu interface. Iu PS - Packet switched variant of the Iu interface. B - Interface between the GSM/UMTS MSC and the VLR. C - Interface between the GSM/UMTS MSC and the HLR. D - Interface between the HLR and VLR. E - Interface between the GSM/UMTS MSC and the VLR. F - Interface between the Nortel GSM/UMTS MSC and the EIR. G - Interface between VLRs using MAP/TCAP signaling over CCS7 SCCP and MTP. Ga - interface between 3G-SGSN and the Charging Gateway Function (CGF) for billing. Ge - Interface between SGSN and the SCP for CAMEL Phase III. Gf - Interface between SGSN and EIR. Gi - Interface between GGSN and the external network. Gn - Interface between 3G-SGSN and GGSN, between different 3G-SGSNs in same PLMN. Gp - Interface between 3G-SGSN and SGSN in different PLMNs. It is used for inter-PLMN. Gr - Interface between the 3G-SGSN and the HLR. X1 - A set of three interfaces (X1-1 – Administration, X1-2 Intercept Related Information, X1-3 Communication Content) between a network and a Lawful Intercept Delivery Domain.
- 16. UMTS traffic classes The UMTS network services have different QoS classes for four types of traffic: • conversational class The conversational class is the typical class for speech telephony. The conversational call is the most demanding class for transfer delays (the maximum affordable value is given by human perception). • streaming class The streaming class has the same real-time constraints as the conversational class. However, since it is a one-way class of service (the user is just listening or viewing) the streaming class is less transfer-delay sensitive than the conversational class. • interactive class The interactive class is not as real-time constraining as the conversational and streaming classes. However, the interactive class requires a very low bit-error rate. • background class The background class is equivalent to the interactive class. The difference between the two classes is that the background class is less delivery-time sensitive and has a lower priority.
- 17. UMTS Base Stations (NodeB) Femto Cell – It is a small, low-power cellular base station designed for use in a home or small business. It connects to the service provider’s network via broadband (such as DSL or cable). Pico Cell - It is capable of providing services to UE within a building.it is used to extend coverage to indoor areas where outdoor signals do not reach well or to add network capacity in areas with very dense phone usage. Micro Cell - It is served by a low power cellular base station (tower), covering a limited area such as a mall, a hotel, or a transportation hub. A microcell uses power control to limit the radius of its coverage area. Macro Cell – It is served by a high power cellular base station (tower) covering larger than microcell. The antennae for macrocells are mounted on ground-based masts, rooftops and other existing structures. It is capable of providing services to UE within a city.
- 18. UMTS Numbers UMTS PLMN (Public Land Mobile Networks) use unique numbers to identify and route calls to UE. The numbers used in UMTS are described as below IMEI - The International Mobile Equipment Identity (IMEI) uniquely identifies the mobile equipment. MSISDN - The Mobile Subscriber Integrated Services Digital Network (MSISDN) number is the unique phone number that consists of Country Code + National Destination Code + Subscriber Number. MSISDNs are allocated according to the CCITT E.164 numbering plan. IMSI - The International Mobile Subscriber Identity (IMSI) is a unique identification of the subscriber. It is stored in the SIM (see below) and Home Location Register (HLR). IMSIs are allocated according to CCITT E.212. TMSI - The Temporary Mobile Subscriber Identity (TMSI) is a unique identity temporarily allocated to visiting UE. The TMSI identifies the UE within a specific VLR as part of the confidentiality service. The TMSI is used in the Circuit Switched (CS) domain. P-TMSI - The P-TMSI (Packet-Temporary Mobile Subscriber Identity) is equivalent to the TMSI, for the Packet Switched (PS) domain. MSRN - The Mobile Subscriber Roaming Number (MSRN) is temporarily assigned to the UE while roaming and is used to terminate calls to the UE.