Wireless Generations 2 Outline Cellular Network Concept First Generation –AMPS Second Generation –Cellular Access Technologies FDMA, TDMA, CDMA –GSM Third Generation –UMTS
Wireless Generations 3 Cell Concept Cell phone is basically a radio Combination of telephone (Alexander Graham Bell) and wireless communications (Guglielmo Marconi) Originally used powerful radio telephones –Problems Needed to be very powerful Not many distinct frequencies (50) Finally split cities into cells to allow cell reuse and reduce the required power – the cell concept –Each cell has a tower –About 800 frequencies across a cell –Size of cell is about 10 sq. miles
Wireless Generations 4 Basics Mobile: Any radio terminal that could be moved during operation or a radio terminal that is attached to a high-speed mobile platform (e.g. a cellular telephone in a fast moving vehicle) whereas the portable describes a radio terminal that can be hand-held and used by someone at walking speed. Subscriber: A mobile or portable user (user pay fee). Subscriber Unit or Mobile Station: Each user communication device. Mobiles or Users: Collective group of users in a wireless system. Many users may actually user portable terminals. Base Stations: A fixed stations in a mobile radio system used for communication with mobile stations. They are located at the center or on the edge of a coverage region and consist of radio channels and transmitter and receiver antennas mounted on a tower. Mobile Switching Center: Switching center, which coordinates the routing of calls in large service area. In a cellular radio system, MSC connects cellular base station and the mobiles to the PSTN. An MSC is also called a mobile telephone switching office (MSTSO).
Wireless Generations 5 Basics Control Channel: Radio Channels used for transmission of call setup, call request, call initiation and other beacon or control purpose. Forward Channel: Transmission of information from the base to a mobile station. Reverse Channel: Transmission of information from the mobile to a base station. Roamer: A mobile station, which operates in a service area (market) other than that from which service has been subscribe. Handoff: The process of transferring a mobile station from one channel or base station to another. Page: A brief message, which is broadcast over the entire service area.
Wireless Generations 6 Classification Simplex: Communication is possible in only one direction (no acknowledge) e.g. Paging Systems. Half duplex: Communication is bi directional but use same channel for both receiving and transmission (push-to-talk and release-to-listen). Half duplex: Communication is bi directional but allows simultaneous transmission and reception b/w subscriber and base station. Implemented by FDD (frequency division duplex; separate channel) or TDD (time division duplex; adjacent time slots).
Wireless Generations 7 Generic WCS (Wireless Communication System) Switch Base Station Base Station Handset PSTN (Public Switched Telephone Network)
Wireless Generations 8 Cellular Communications Cells Radio Tower Frequencies Clusters Frequency Reuse Cell Splitting Handoff PSTN
Wireless Generations 9 Cellular Call Setup 1. Phone scans for towers for strongest signal on control channel 2.Transmit Mobile Identification Number (MIN), Electronic Serial Number (ESN), and telephone number 3. MTSO sets up call Mobile Telephone Switching Office MTSO Cellular Service Subscriber Car Phone = 2W Hand Phone = 0.7W PSTN
Wireless Generations 10 Wireless “Generations” First Generation (1989) Analog voice using FM channels Also called AMPS (Advanced Mobile Phone System) Solved the issue of “mobility”
Wireless Generations 11 Multiple Access The basis for any mobile system is its air interface design, and particularly the way the common transmission medium is shared between users, that is, multiple access scheme. Multiple access scheme defines how the radio spectrum is divided into channels, and how the channels separate the different users of the system. FDMA, TDMA, CDMA
Wireless Generations 12 AMPS AMPS – Advanced Mobile Phone System Analog cell phone standard deployed across North America Approved by FCC in 1983 – first deployed in Chicago Utilizes 824MHz-894MHz frequencies 832 available frequencies –790 Voice –42 Data (signaling) 30 KHz wide – voice quality FDMA NAMPS – Narrowband AMPS – –3x AMPS capacity
Wireless Generations 13 Wireless “Generations” 2G - Second Generation (1998) Digital modulation used for speech compression Still a voice-only network, except for limited circuit switched data capability Several different system types: –TDMA - time division multiple access –CDMA - code division multiple access –GSM - global mobile system (the original acronym is French) – Group Special Mobile. Solved the issue of “capacity”
Wireless Generations 14 Cellular Access Technologies There are three common technologies used by cell phone networks for transmitting information: Frequency Division Multiple Access (FDMA) –FDMA puts each call on a separate frequency. Time Division Multiple Access (TDMA) –TDMA assigns each call a certain portion of time on a designated frequency. Code Division Multiple Access (CDMA) –CDMA gives a unique code to each call and spreads it over the available frequencies. The last part of each name is multiple access. This simply means that more than one user (multiple) can use (access) each cell.
Wireless Generations 15 FDMA In a FDMA system, the total system bandwidth is divided into several frequency channels that are allocated to users MHz MHz 45 MHz
Wireless Generations 16 TDMA In a TDMA system, one frequency channel is divided into time slots that are allocated to users, and the users only transmit during their assigned timeslots. Examples of demand-assignment contention less protocols are token bus and token ring LANs described by the IEEE in the and standards MHz MHz Digital decoding 6.7MS Digital encoding
Wireless Generations 17 CDMA CDMA takes an entirely different approach from TDMA. CDMA, after digitizing data, spreads it out over the entire bandwidth it has available. Multiple calls are overlaid over each other on the channel, with each assigned a unique sequence code. CDMA is a form of spread spectrum, which simply means that data is sent in small pieces over a number of the discrete frequencies available for use at any time in the specified range. Digital decoding 1850MHz 1990MHz CDMA
Wireless Generations 18 GSM GSM – Groupe Spécial Mobile GSM is an international digital cellular standard in Europe, Asia, Australia, and Africa Originally, the acronym GSM stood for Groupe Spécial Mobile, a group formed by the Conference of European Posts and Telegraphs (CEPT) in 1982 to research the merits of a European standard for mobile telecommunications. Commercial service using the GSM system did not actually start until GSM was developed as a digital system using TDMA technology.
Wireless Generations 19 GSM GSM uses TDMA 900 MHz – 1800 MHz (Europe and Asia) 1900 MHz (North America) Used for digital PCS services One phone for all standard GSM worldwide except North America To switch providers – switch SIM (subscriber identification modules) cards
Wireless Generations 20 GSM Features Uses encryption to make phone calls more secure Data networking Short Message Service (SMS) for text messages and paging Call forwarding Caller ID Call waiting
Wireless Generations 21 GSM Network Architecture BTS BSC TRAU Um AbisAter A PSTN D C MSC HLR/ AuC BSS NSS MS VLR MS – Mobile Station BSS – Base Station Subsystem BTS – Base Trans Station BSC – Base Station Controller TRAU - Transcoder / Rate Adaptation Unit MSC – Mobile Switching Centre NSS – Network Switching Subsystem VLR – Visitor Location Register HLR – Home Location Register AuC – Authentication Centre
Wireless Generations 22 Evolving Standards and Terminology 1st Generation AMPS Bell Wireless Alliance Cantel 2nd Generation IS-95A (CDMA) and IS-136 (TDMA) Bell Wireless Alliance (CDMA) ATT Rogers (Cantel) (TDMA) Clearnet (CDMA) Microcell (GSM)
Wireless Generations 23 Wireless “Generations” 2.5 Generation Packet switched data at rates up to 144 kbps Several different types: –GPRS - evolved from GSM –1xRTT - evolved from CDMA Will require a Core IP Network Solves the issue of “mobility” with packet data
Wireless Generations 24 GPRS GPRS – General Packet Radio Services An evolution of GSM Higher speed data services GPRS has seamless interface capabilities to TCP/IP
Wireless Generations 25 From GSM to GSM/GPRS Network BTS BSC TRAU Um AbisAter A PCU Agprs Frame Relay Backbone Gb MSC VLR PSTN SGSN Private IP Backbone GGSN Gn External Packet Networks Intranet, Internet Gi HLR/ AuC D C Gr MS MS – Mobile Station BSS – Base Station Subsystem BTS – Base Trans Station BSC – Base Station Controller TRAU - Transcoder / Rate Adaptation Unit MSC – Mobile Switching Centre NSS – Network Switching Subsystem VLR – Visitor Location Register HLR – Home Location Register AuC – Authentication Centre\ SGSN – Serving GPRS Support Node GGSN – Gateway GPRS Support Node
Wireless Generations 26 Research in Motion GPRS in Canada/US BlackBerry
Wireless Generations 27 Wireless “Generations” 3G -Third Generation (future) Packet switched data at rates up to 2.4 Mbps ITU standard - standards still evolving Adds the high data rate component and quality of service parameters Introduces an Open Standard concept that will foster increased development of wireless applications, much like the Internet.
Wireless Generations 28 UMTS Universal Mobile Telecommunications System Third Generation (3G) Technology Uses W-CDMA, FDD, TDD Phase 1, called Release 1999 (R99) is an evolution of the GSM network architecture Key features: –Open standards based –all IP in the core –decentralized network –service based In plain English : a network that will allow IP devices to roam while providing 384 kbps to 2 Mbps access rates. If successful, may become the “World Standard”
Wireless Generations 29 UMTS Will provide 2 Mbps in a local environment Will provide 384 kbps at highway velocities Will use IP over ATM to control different data types: –controlling data latency and quality Will use W-CDMA-FDD for macro mobility at 144 kbps Will use W-CDMA-TDD for micro mobility at 2 Mbps
Wireless Generations 30 UMTS Architecture UMTS Terrestrial Radio Access Network (UTRAN) ATM Backbone Node B (BTS) Uu RNC - Radio Network Controller Iu (CS & PS) RNC Iur Iu (CS & PS) Node B (BTS) Uu Access Network Core Network Packet Domain Circuit Domain UE ATM Backbone Iub (ATM)
Wireless Generations 31 UMTS Interfaces Access NetworkCore Network Private IP Backbone Node B (BTS) Uu Iub (ATM) RNC Iu (CS & PS) RNC Iur Node B (BTS) Uu TRAU MSC VLR SGSN GGSN Gn Gi Iu CS Iu PS HLR/AuC D C Gr UE PSTN External Packet Networks ATM Backbone ATM Backbone Iub (ATM) Iu (CS & PS)