UMTS ARCHITECTURE ECE 2526 – MOBILE COMMUNICATIONS Monday, 16 March 2020 1
REVIEW - BLOCK DIAGRAM OF GSM MOBILE STATION
UMTS ARCHITECTURE CORE NETWORK (CN) USER EQUIPMENT (UE) 1.HLR RADIO NETWORK SUBSYSTEM (RNS) OR 2.VLR 1. Transmitter/Receiver UMTS RADIO ACCESS NETWORK (UTRAN ) 3.EIR 2. Baseband processing 3. USIM 4.MSC 1.R adio N etwork C ontroller 5.AuC 2.Node B 6.GMSC 7.SGSN 8.GGSN Iu Uu Interface Interface
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. 4
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 was chosen because the considerably greater functionality that the UE could have. It could also be anything between a mobile phone used for talking to a data terminal attached to a computer with no voice capability. 5
INTEGRATED CIRCUIT CARD IDENTIFIER (ICC-ID) • Each SIM is internationally identified by its ICC-ID. • ICC-IDs are stored in the ROM and are also engraved or printed on the SIM card. • ICC-ID is defined by the ITU-T recommendation E.118. • ICC-ID is 19 or 20 digits long having the following fields: 1. Use of Sim, e.g 89 for telecommunications 2. Country code 3. Mobile Network code 4. Vendor 5. Serial Number 6. Check digit calculated using the Luhn algorithm. 6
EXAMPLE OF ICC-ID ICC-ID for AirTel SIM Card is shown below: 89 - 254 - 03 - 1132 - 10528309 - 8 Mobile Serial Checksum Telecommunication Country Vendor Network Number Use Code-Kenya Code 7
FEATURES OF USIM Some of the features of the next generation SIM cards are: 1. Support for advanced Applications e.g. address book, calendar back-up, messaging, teleconferencing, file transfers, banking and access control 2. Support for Mobile Near Field Communication (NFC) 3. Smart Card Web Server Web apps running right on SIM Cards 4. High-capacity with more memory/capacity 8
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. 9
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. 10
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. 11
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. 12
UMTS TERRESTRIAL RADIO ACCESS NETWORK (UTRAN) Physical layer within UMTS 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- 2100 MHz in Kenya. 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. 13
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. 14
UMTS RADIO ACCESS NETWORK(2) 2. Node B: Node B is the term used within UMTS to denote the base station transceiver. 3. Node B: 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 15
RADIO NETWORK SUBSYSTEM 1. Radio Network Subsystem (RNS): A lso known as the UMTS Radio Access Network (UTRAN), provides and manages the air interface for the overall network. 2. RNS is the equivalent of the previous Base Station Subsystem or BSS in GSM. 16
IU INTERFACE The Iu interface is specified at the boundary between the Core Network and UTRAN. CS Domain Circuit-Switched domain. Mainly used for voice. PS Domain Packet-Switched domain. Mainly used for data/video services BC Domain Broadcast domain used for broadcast services. Further Reading 17 3GGP Iu Interface Specification
UMTS ARCHITECTURE - REVISITED Baseband Processing RF Circuitry CS Domain Circuit Switched PS Domain Packet switched 18
GSM SPEECH PROCESSING ETI 2511 Monday, 15 May 2017 19
BASIC SPEECH PROCESSING FUNDAMENTALS (1) Basic GSM Band 890 + n*0.2 Basic GSM Band 20 890 + n*0.2 +45
GSM SPEECH PROCESSING FUNDAMENTALS -REVISITED 1. A GSM frame is 4.61msec long. 2. Each time slot is therefore 4.61/8 = 577µsec 21
SPEECH PROCESSING IN GSM Data Burst at 12 Kbps Adaptive Filter Removes redundant Parts in each data stream sample 22
QPSK MODULATION USED IN GSM 1. Each byte of data is split into four pairs of bits. 2. Each pair of bits is assigned a particular phase for I(t) and Q(t). 3. The modulated signal is the sum of the two sinusoidal waves, with a phase shift depending on the logic symbol. 23
WHY COMPRESSION IS NECESSARY IN GSM CODEC? 1. If speech were digitised in a linear fashion it would require a high data rate that would occupy a very wide bandwidth. 2. It is necessary to compress the data to send it through the available channel. 3. Speech is captured at a high enough sample rate and resolution to allow clear reproduction of the original sound. 4. It must then be compressed in such a way as to maintain the fidelity of the audio over a limited bit rate, error-prone wireless transmission channel. 5. At the receiver, the compressed data is expanded to regenerate the audio. 24
GSM CODEC 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. 25
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. 26
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 27 coded as 3-bit
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