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UMTS Architecture Overview UMTS Architecture Overview by Dr Paul Raby by Dr Paul Raby Public Land Mobile Network (PLMN) ▪ A PLMN can be regarded as an independent telecommunications entity. ▪ A PLMN is defined as: ▫ One or more switches with: ▪ a common numbering plan ▪ a common routing plan ▫ Switches act as the interface to external networks ▪ The PLMN can be separated into ▫ Core Network ▫ Access Network Core Network Access Network PLMN System Architecture Overview User Equipment UMTS Terrestrial Radio Access Network Core Network U U I U UE UTRAN CN UMTS High Level Architecture System Architecture Overview Major Network Elements in UMTS PLMN, PSTN, ISDN Internet, X25 Packet Network U U UE C U USIM ME Mobile Equipment UMTS SIM CN MSC/VLR SGSN GGSN GMSC HLR Serving GSN Gateway GSN Gateway MSC Mobile Switching Centre Home Location Register I U UTRAN I Ub I Ur Node B Node B Node B Node B RNC RNC Radio Network Controller Radio Network Controller I u-ps I u-cs I Ub System Architecture Overview General UTRAN Architecture U U I U UE UTRAN I Ub I Ur Node B Node B Node B Node B RNC RNC Radio Network Controller Radio Network Controller I u-ps I u-cs I Ub CN (MSC) CN (SGSN) System Architecture Overview Elements of UTRAN ▪ Radio Network Controller ▫ Owns and controls radio resources in its domain (BSC in GSM) ▫ Service Access Point for all services that UTRAN provides for the CN ▫ Note: Service RNC (SRNC) and Drift RNC (DRNC) are subsets ▫ Note: Control RNC (CRNC ) whichever RNC is talking to the UE ▪ Node B ▫ Acts as the radio base station (BTS in GSM) ▫ Converts the data flow between the I ub and U u interfaces System Architecture Overview Major Interfaces in UMTS ▪ There are four major new interfaces defined in UMTS ▫ I u ▪ The interface between UTRAN and the CN ▫ I ur ▪ The Interface between different RNCs ▫ I ub ▪ The interface between the Node B and the RNC ▫ U u ▪ The air interface RNC Node- B RNC UE CN U u I u I ub I ur System Architecture Overview UMTS Interface Implementation ATM/IP Network RNC Node B Node B Node B MSC RNC SGSN Node B I ub I u_cs I u_ps I ur System Architecture Overview Handover in UMTS ▪ There are 3 basic types of handover ▫ Intra frequency handovers ▪ Handovers between 2 UMTS carriers at the same frequency ▪ These can be soft handovers ▫ Inter frequency handovers ▪ Handovers between 2 UMTS carriers at different frequencies ▪ These are hard handovers ▫ Inter system handovers ▪ Handovers between UMTS and GSM carriers ▪ These are hard handovers System Architecture Overview Macrodiversity between Node B’s ▪ If Active Set consists of ▫ two connections to cells parented to different Node Bs ▫ then the combining of the two channels occurs at the RNC ▪ This is known as a soft handover ▪ This doubles the transmission ‘cost’ of the call RNC Node B Cell Cell Cell Node B Cell Cell Cell I ur I u U u System Architecture Overview [...]... Cell Cell Cell Uu System Architecture Overview Architecture of a UMTS bearer service Each bearer service on a specific layer provides services using layers below TE UE UTRAN CN CN edge node gateway TE End-to-End TE/UE Local Bearer UMTS Bearer Radio Access Bearer Radio Bearer Iu Bearer UTRA FDD/TDD Physical Bearer External Bearer CN Bearer Backbone Network System Architecture Overview UMTS Protocol Stratums... minutes System Architecture Overview Protocol Model for UTRAN Interfaces ▪ Protocol structures in UTRAN are designed in layers and planes ▪ They are seen as logically independent of each other ▫ However they will physically interact ▪ Being logically independent allows for changes to blocks in the future theoretically! System Architecture Overview General Protocol Model for UTRAN Terrestrial Interfaces System. .. data/control) ▫ UDP/IP or RTP/UDP/IP ( release 6 ? ) System Architecture Overview Vertical Planes in the General Protocol Model ▪ The Control Plane is provided for all UMTS specific control signalling including: ▫ Application Protocols ▫ Signalling Bearers ▪ The User Plane is provided for all data sent and received by the user including: ▫ Data Streams ▫ Data Bearers System Architecture Overview Vertical Planes... Application Part, ALCAP Transport Network User Plane Transport Network Control Plane ALCAP Transport Network User Plane UMTS Technology Overview UMTS Technology Overview CDMA - Direct Sequence Spread Spectrum frequency code Frame Period (we may still need frames/timeslots for signaling) time UMTS Technology Overview CDMA Spreading •Essentially Spreading involves changing the symbol rate on the air interface... Stream P f Code Chip Stream UMTS Technology Overview Spreading and Despreading Tx Bit Stream Spreading X Code Chip Stream Air Interface Chip Stream Despreading X Code Chip Stream Rx Bit Stream 1 -1 UMTS Technology Overview Spreading and Despreading with code Y Tx Bit Stream Spreading X Code Chip Stream Air Interface Chip Stream Despreading X Code Chip Stream Y Rx Bit Stream 1 -1 UMTS Technology Overview... correlate if they are time shifted UMTS Technology Overview OVSF codes ▪ Orthogonal Variable Spreading Factor Codes can be defined by a code tree: Cch,4,0 =(1,1,1,1) Cch,2,0 = (1,1) Cch,4,1 = (1,1,-1,-1) Cch,1,0 = (1) Cch,4,2 = (1,-1,1,-1) Cch,2,1 = (1,-1) Cch,4,3 = (1,-1,-1,1) SF = 1 SF = 2 SF = 4 ▫ SF = Spreading Factor of code (maximum 512 for UMTS in the DL, 256 in the UL) UMTS Technology Overview Vital... Commonly the processing gain is referred to as the Spreading Factor UMTS Technology Overview Spreading in noise Rx Signal (= Tx Signal + Noise) Tx Signal P P f P f P Channel f f Signal Spreading Code Spreading Code P Signal f Wideband Noise/Interference ▪ The gain due to Despreading of the signal over wideband noise is the Processing Gain UMTS Technology Overview Visualising the Processing Gain W/Hz W/Hz... f UMTS Technology Overview Separating BaseStations ▪ Summarising: ▫ Channelisation Codes S2 C1 C2 C3 ▪Are used to separate channels from a single cell ▫ Scrambling Codes ▪Are used to separate cells from each other rather than purely channels S1 C1 C2 C3 ▪ Different base stations will use the same spreading codes with separation being provided by the use of different scrambling codes S3 C1 C2 C3 UMTS. .. the UE’s ▫ Scrambling Codes ▪Are used to separate UEs from each other rather UMTS Technology Overview Spreading Codes = Channelisation Codes ▪ Channelisation codes are orthogonal ▫ Which provides channel separation ▪ Number of codes available is dependant on length of code ▪ Channelisation codes are used to spread the signal UMTS Technology Overview Channelisation Code Generation ▪ Channelisation codes... of layer 3 L7 L6 L6 L5 L5 L4 L4 L3 upper Access Stratum • Non Access Stratum ▪ Non-access Stratum L7 L3 upper L3 lower L3 lower L3 lower L3 lower L2 L2 L2 L2 L1 L1 L1 L1 UE Uu UTRAN Iu CN System Architecture Overview UMTS QoS Classes ▪ Conversational ▫ Speech over CS bearer ▫ Voice over IP, PS bearer ▫ Delay critical, imposed by human perception ▪ Streaming ▫ Multimedia streaming ▫ Using buffers, for . Network Access Network PLMN System Architecture Overview User Equipment UMTS Terrestrial Radio Access Network Core Network U U I U UE UTRAN CN UMTS High Level Architecture System Architecture Overview Major. interface RNC Node- B RNC UE CN U u I u I ub I ur System Architecture Overview UMTS Interface Implementation ATM/IP Network RNC Node B Node B Node B MSC RNC SGSN Node B I ub I u_cs I u_ps I ur System Architecture Overview Handover in UMTS ▪ There. flow between the I ub and U u interfaces System Architecture Overview Major Interfaces in UMTS ▪ There are four major new interfaces defined in UMTS ▫ I u ▪ The interface between UTRAN and