UMTS ARCHITECTURE ECE 2526 – MOBILE COMMUNICATION Monday, 25 March 2019 1
GENERATIONS OF CELLULAR TECHNOLOGY 4G 4G LTE TE MIMO MIMO N ordic M obile T elephony (est. 1981) AM AMPS PS(80 (800MHz) 0MHz) EDGE EDGE IMT2000 IMT2000 2
UMTS NETWORK ARCHITECTURE The UMTS network architecture is divided into three main elements: UMTS ARCHITECTURE 1. User Equipment (UE): The User Equipment (UE) is the name given to what was previous termed the Mobile Station(MS), or cell phone. The new name CORE NETWORK (CN) was chosen because the considerably greater 1. HLR USER EQUIPMENT (UE RADIO NETWORK 2. VLR functionality that the UE could have. It could also be SUBSYSTEM (RNS) 3. EIR 1. Transmitter/Receiver anything between a mobile phone used for talking to 4. MSC 2. Baseband processing 1. Radio Network Controller 5. AUC a data terminal attached to a computer with no voice 3. USIM 2. Node B 6. GMSC capability. 7. SGSN 8. GGSN 2. Radio Network Subsystem (RNS): The RNS also known as the UMTS Radio Access Network (UTRAN), is the equivalent of the previous Base Station Subsystem or BSS in GSM. It provides and manages the air interface fort he overall network. 3. Core Network: The core network provides all the Uu Iu central processing and management for the system. Interface Interface It is the equivalent of the Network Switching Subsystem (NSS) in GSM. 3
UMTS ELEMENTS Radio Network Controller (RNC) The Iu interface • Radio resource management Circuit Switched (CS) Domain S pecified the boundary between • Mobility management • Circuit Switching the Core Network and UTRAN. • Switching • Links to PSTN • Encryption • Location Management • Billing, etc Packet Switched (PS) Domain Packet Switcting Link to Internet backbone Packet billing Broadcast Connection (BC) Domain Iu – Broadcast Connection is responsible for delivery to multiple devises 4
UMTS ARCHITECTURE Circuit Switched • Baseband Processing • RF Circuitry Packet switched 5
USER EQUIPMENT (UE) The User Equipment (UE) Consists of the following elements: 1. UE RF circuitry: Handles all elements receiver and transmitter signals. One of the major challenges for the RF power amplifier was to reduce the power consumption. The form of modulation used for W-CDMA requires the use of a linear amplifier. These inherently take more current than non linear amplifiers which can be used for the form of modulation used on GSM. Accordingly to maintain battery life, measures were introduced into many of the designs to ensure the optimum efficiency. 2. Baseband processing: The base-band signal processing is mainly of digital processor-based. The circuitry is optimised to reduce the current consumption. 3. Battery: Lithium Ion (Li-ion) battery which are small and relatively light while still retaining or even improving the overall life between charges. 4. Universal Subscriber Identity Module, USIM: Plays the same function as the SIM in GSM network. 6
UMTS DATA RATES Bit rate Codec name (kbps) 1. Full rate 13 2. Enhanced Full Rate (EFR) 12.2 3. Half rate 5.6 4. Adaptive Multirate (AMR ) 12.2 - 4.75 5. Adaptive Multirate Wideband (AMR-WB) – 23.85 - 6.60 baseband is enhanced to the range 50 – 7,000 Hz. 7
SALIENT FEATURES OF ADAPTIVE MULTIRATE (AMR) 1. AMR uses 20ms frames . 2. Discontinuous transmission is employed so that when there is no speech activity the transmission is cut. 3. Voice Activity Detection (VAD) is used to indicate when there is only background noise and no speech. 4. Comfort Noise Generator (CNG) is added at the receiver to provide some background noise, even when no speech data is being transmitted. This provides the feedback for the user that the connection is still present. 8
WHAT IS TRANSMITTED FOR VOICE IN GSM? 20ms of 104 Kbps stream = 2080 bits Best coefficients are selected get the best approximation of the 20mS sample Low order coefficients are coded as 6-bit while Higher order are 9 coded as 3-bit
3G UMTS CORE NETWORK The UMTS core network may be split into two different areas: 1. Circuit switched elements: These elements are primarily based on the GSM network entities and carry data in a circuit switched manner, i.e. a permanent channel for the duration of the call. 2. Packet switched elements: These network entities are designed to carry packet data. This enables much higher network usage as the capacity can be shared and data is carried as packets which are routed according to their destination. 10
CIRCUIT SWITCHED ELEMENTS Mobile switching centre (MSC): This is essentially the same as that within GSM, and it manages the circuit switched calls under way. Gateway MSC (GMSC): This is effectively the interface to the external networks. 11
PACKET SWITCHED ELEMENTS SERVING GPRS SUPPORT NODE (SGSN) The SGSN provides the following functions within the UMTS network architecture. 1. Mobility management 2. Session management 3. Interaction with other areas of the network 4. Billing GATEWAY GPRS SUPPORT NODE (GGSN) The Gateway Support Node performs the following functions: 1. Handles inter-working between the UMTS packet switched network and external packet switched networks. 2. When the GGSN receives data addressed to a specific user, it checks if the user is active and then forwards the data to the SGSN serving the particular user. 12
SHARED ELEMENTS 1. Home location register (HLR): 2. Equipment identity register A database which contains all (EIR): The EIR is the entity that the administrative information decides whether a given UE about each subscriber along equipment may be allowed onto with their last known location. the network. Using HLR, the UMTS network 3. Authentication centre (AuC) : is able to route calls to the The AuC is a protected database relevant RNC and Node B. that contains the secret key also contained in the user's USIM card. AUC generates the triplets authentication and encryption triplets. 13
UMTS TERRESTRIAL RADIO ACCESS NETWORK (UTRAN) Physical layer within UMTS / WCDMA is totally different to that employed by GSM. 1. It employs a spread spectrum transmission in the form of CDMA rather than the TDMA transmissions used for GSM. 2. It uses different frequencies to those allocated for GSM. 3. The network, or UMTS Radio Access Network is known as the UTRAN. 4. Sometimes the UTRAN may also be known as the Radio Network Subsystem, or RNS. 14
UMTS RADIO ACCESS NETWORK(1) The UMTS Radio Access Network, UTRAN, or Radio Network Subsystem, RNS comprises two main components, i.e Radio Network Controller and Node B. 1. Radio Network Controller, RNC : This element of the UTRAN / radio network subsystem controls the Node Bs that are connected to it, i.e. the radio resources in its domain. Functions: a) The RNC undertakes the radio resource management b) Mobility management functions. c) Data encryption / decryption is performed to protect the user data from eavesdropping. 15
UMTS RADIO ACCESS NETWORK(2) 2. Node B: Node B is the term used within UMTS to denote the base station transceiver. This part of the UTRAN contains the transmitter and receiver to communicate with the UEs within the cell. It participates with the RNC in the resource management. Node B is the 3GPP term for base station, and often the terms are used interchangeably 16
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