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Mobile Cellular Systems and Standards

Mobile Cellular Systems and Standards. Lecture 1. Course Overview. In this course you will learn the fundamental techniques for the design and analysis of mobile communication systems. The course deals with the fundamental physical layer principles and system level study of modern wireless

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Mobile Cellular Systems and Standards

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  1. Mobile Cellular Systems and Standards Lecture 1

  2. Course Overview In this course you will learn the fundamental techniques for the design and analysis of mobile communication systems. The course deals with the fundamental physical layer principles and system level study of modern wireless communication systems. Wireless systems and standards like GSM, GPRS, IS-95, CDMA-2000, WCDMA, UMTS, HSPA, and LTE will be studied from system level perspective.

  3. Grading Policy • Quizzes & Assignments 10% • Technical Report/Presentation 15% • Midterm Exam 25% • Final Exam: 50%

  4. Course Details (Helping Text) • Wireless Communications: Principles and Practice, 2/e, by Theodore S. Rappaport • GSM Networks: Protocols, Terminology and Implementation by Gunnar Heine • WCDMA for UMTS: Radio Access for Third Generation Mobile Communications, Second Edition, edited by Harri Holma and Antti Toskla. • 3rd Generation Partnership Project Technical Specifications, ftp://ftp.3gpp.org/Specs/. • LTE - The UMTS Long Term Evolution: From Theory to Practice, edited by Stefania Sesia, Issam Toufik, Matthew Baker

  5. Course Details • Pre-Requisites Digital Communications (undergraduate) Wireless Communications(undergraduate)

  6. Course Contents (Tentative) • Focus will be more on Architecture, Physical layer and data link layer of 2G/3G/4G Mobile Systems • Intro to Mobile Communication Systems • Cellular Concepts • Cellular & GSM System (2G) • GPRS & EDGE • IS95 CDMA (2G) • CDMA 2000 and EVDO (3G) • WCDMA & UMTS (3G) • HSPA (HSUPA & HSDPA) (3.5G) • LTE (4G)

  7. Today's Lecture • Introduction to Wireless Communication • Historical Evolution and Trends in Wireless Communications • A survey of Wireless Generations • Terminology and Definitions of Wireless Communication Systems

  8. Introduction to Wireless Communication Cut the WIRE

  9. Wireless History • Ancient Systems: Smoke Signals, Carrier Pigeons • Radio invented in the 1880s by Marconi • Many sophisticated military radio systems were developed during and after WW2 • Cellular has enjoyed exponential growth since 1988, with almost 3 billion users worldwide today • Ignited the wireless revolution • Voice, data, and multimedia becoming ubiquitous • Use in third world countries growing rapidly • Wifi also enjoying tremendous success and growth • Wide area networks (e.g. Wimax) and short-range systems other than Bluetooth (e.g. UWB) less successful

  10. Design Challenges Wireless channels are a difficult and capacity-limited broadcast communications medium Traffic patterns, user locations, and network conditions are constantly changing Applications are heterogeneous with hard constraints that must be met by the network Energy and delay constraints change design principles across all layers of the protocol stack

  11. Objectives of Wireless Systems Large Capacity Efficient use of Resources (Spectrum) Adaptability to traffic density Quality of Service Affordability

  12. The Wireless Revolution • Cellular is the fastest growing sector of communication industry(exponential growth since 1982, with 3 billion users worldwide today) • Four generations of wireless • First Generation (1G): Analog 25 or 30 KHz FM, voice only, mostly vehicular communication • Second Generation (2G): Narrowband TDMA and CDMA, voice and low bit-rate data, portable units. • 2.5G increased data transmission capabilities • Third Generation (3G): Wideband TDMA and CDMA, voice and high bit-rate data, portable units • Fourth Generation (in progress):true broadband wireless: WIMAX, 3G LTE

  13. Future Generations 4G 3G 2G Rate 802.11b WLAN 2G Cellular Mobility

  14. Multimedia Requirements Voice Data Video Delay <100ms - <100ms Packet Loss <1% 0 <1% BER 10-3 10-6 10-6 Data Rate 8-32 Kbps 1-100 Mbps 1-20 Mbps Traffic Continuous Bursty Continuous

  15. Quality-of-Service (QoS) QoS refers to the requirements associated with a given application, typically rate and delay requirements. It is hard to make a one-size-fits all network that supports requirements of different applications. QoS for all applications requires a cross-layer design approach.

  16. Wireless communication Layers Application Transport Layer Network Access Link Physical Layer

  17. code code P P FDMA TDMA time t time t 1 2 3 TS 3 TS 2 TS 1 frequency f frequency f code Multiple Access methods P CDMA time t Multiple method BS & MS shareknowledge about Fig. 9 (TM2100EU03TM_0001 Transmission Principles, 19) FDMA TDMA CDMA Frequency Time PN code 3 2 1 frequency f

  18. First Generation (1G) 1G systems emerged in the late 1970s and lasted through the 1980s These analog systems were the first true mobile phone systems, known at first as "cellular mobile radio telephone." Advanced Mobile Phone Service (AMPS) Nordic Mobile Telephone (NMT) and Total Access Communication System (TACS).

  19. Advanced Mobile Phone Service (AMPS) First-generation cellular took off in 1982 with the deployment of commercial AMPS in U.S. Originally, AMPS operated in the 800 MHz frequency band FDMA employed Channel bandwidth: 30kHz Uplink Frequency Range: 824-849 MHz Downlink Frequency Range:869-894 MHz The band accommodated 832 duplex channels among which 21 were reserved for call setup and the rest for voice communication

  20. Total Access Communication System (TACS) TACS is the European version of AMPS After its introduction in U.K. in 1985, over 25 countries offered TACS services Channel Bandwidth:25 kHz each Uplink Frequency Range: 890-915 MHz Downlink Frequency Range: 935-960 MHz

  21. TACS Extended TACS (ETACS) An additional 16 MHz of channel bandwidth was added to accommodate more channels to form ETACS JTACS Japanese version of TACS The only significant differences were the frequency bands and number of channels Narrowband TACS (NTACS) Another variation of TACS which reduced channel bandwidth from 25 kHz to 12.5 kHz.

  22. Nordic Mobile Telephone (NMT) NMT system was developed by the telecommunications administrations of Sweden, Norway, Finland, and Denmark to create a compatible mobile telephone system in the Nordic countries The first commercial NMT 450 cellular system was available at the end of 1981 Due to its rapid success and limited capacity of the original system design, NMT 900 system version was introduced in 1986

  23. NMT NMT 450 used a lower frequency (450 MHz) and higher maximum transmitter power level which allowed a larger cell site coverage areas NMT 900 used a higher frequency (approximately 900 MHz band) and a lower maximum transmitter power which increased system capacity NMT 450 and 900 could co-exist

  24. NMT When NMT mobile phones accessed the cellular system, they either found an unused voice channel and negotiated access directly or began conversation without the assistance of a dedicated control channel Since scanning for free voice channels is very time consuming, NMT 900 used a dedicated control channel called the calling channel NMT 450 was frequency duplex with 180 channels (except Finland which only had 160 channels) Channel Bandwidth=25 kHz with a frequency duplex spacing of 10 MHz NMT 900 system had 999 channels

  25. Problems with 1G Numerous incompatible 1G services emerged around the world during 1980s each carrier delivered service to a limited serving area there were no standards to enable roaming channel capacity was rapidly being exhausted.

  26. Second Generation (2G) Designed in the 1980s Based on digital technology rather than analog Provided circuit- switched data communication services at a low speed Allowed multiple conversations on the same channel Primary use: speech transmission New features: Fax Data transmission Message services New fraud prevention and encryption technologies in response to the security concerns of cellular users

  27. 2G A negative consequence of these technological advances was a competitive rush to design and implement digital systems leading to a variety of different and incompatible standards, mainly Global System for Mobile Communication (GSM) Interim Standard-54 (IS-54) / Interim Standard -136 (IS-136) using Time Division Multiple Access (IS-54 / IS-136 TDMA) Extended TDMA (E-TDMA) Personal Digital Cellular (PDC) (Japanese Standard) Interim Standard -95 CDMA (IS-95 CDMA)

  28. Global System for Mobile Communication (GSM) Initially created to provide a single standard pan-European cellular system Uses TDMA technology Its development began in 1982, and the first commercial GSM digital cellular system was activated in 1991 GSM has evolved to be used in a variety of systems and frequencies (900 MHz, 1800 MHz and 1900 MHz)

  29. IS-54/IS-136 TDMA Uses TDMA technology All IS-136 TDMA digital radio channels are divided into frames with 3 time slots Evolved from the IS-54 specification that was developed in U.S. in the late 1980’s to allow the gradual evolution of AMPS to digital service IS-136 included circuit switched data and text messaging like GSM. Also referred to as Digital AMPS (DAMPS) or North American Digital Cellular (NADC)

  30. IS-54/IS-136 TDMA Primary Features: Ease of adaptation to the existing AMPS This is due to the fact that IS- 136 radio channels retain the same 30 kHz bandwidth as AMPS channels The development of dual mode mobile telephones operating on either IS-136 digital traffic (voice and data) channels or the existing AMPS radio channels

  31. Extended TDMA (E-TDMA) Developed by Hughes Network Systems in 1990 as an extension of IS-136 TDMA ETDMA uses the existing TDMA radio channel bandwidth and channel structure and its receivers are tri-mode as they can operate in AMPS, TDMA, or ETDMA modes Difference b/w TDMA & E-TDMA TDMA assigns a time slot to a specific conversation whether or not anyone is speaking at that moment, which wastes Bandwidth ETDMA assigns subscribers dynamically on requirement basis

  32. IS-95 CDMA Based on CDMA technology Initially developed by Qualcomm in the late 1980’s CDMA is a form of Spread-Spectrum communication that has been used in military applications for many years Spreading of signals is achieved by Direct Sequence method in which digital data is directly coded at a much higher frequency The code is generated pseudo-randomly, the receiver knows how to generate the same code, and correlates the received signal with that code to extract the data Since Spread Spectrum signals are wide, they transmit at a much lower spectral power density than narrowband transmitters

  33. IS-95 CDMA Allows for voice or data communications on either a 30 kHz AMPS channel (when used on the 800 MHz cellular band) or a new 1.25 MHz CDMA channel CDMA channels are unique in the sense that CDMA multiplies (and therefore spreads the bandwidth of) each signal with a unique Pseudo-random Noise (PN) code that identifies each user within a channel and is independent of the data of that user. Each CDMA channel contains the signals of many ongoing calls (voice channels) together with pilot, synchronization, paging, and control channels Receivers select the signal they are receiving by correlating (matching) the received signal with the proper PN sequence. The use of unique codes allows multiple users to access the same frequency band simultaneously thus rendering CDMA as highly spectrally efficient.

  34. IS-95 CDMA Each IS-95 CDMA channel is divided into 64 separate (PN coded) channels A few of these channels are used for control, and the remaining carry voice information and data Original IS-95 throughput rate for a dedicated user specified as 9.6 kbps Later on this rate was improved to 14.4 kbps for IS-95A In IS-95B each user can be assigned up to 8 traffic channels simultaneously for a data throughput of 115.2 kbps per user In 1997 the CDMA Development Group (CDG) registered the trademark cdmaOne TM as a label to identify 2G systems based on the IS-95 standard and related technologies

  35. 2.5 G During 1990’s, the telecommunications industry, recognizing the need for a single global standard of wireless communication, began making efforts to define a Third Generation (3G) system which would eliminate previous incompatibilities and become a truly global standard However, the consumer market was pressing for improved data transmission and features in the present, not sometime in the future. In 2001, this led to an intermediate step between 2G and 3G, called 2.5G.

  36. 2.5 G Key Features: Use digital packet switching technology, providing increased capacity on the 2G radio channels and higher throughput (up to 384 kbps) for data service The data channels are optimized for packet data, which introduces access to the internet from mobile devices, streaming video and enhanced multimedia applications

  37. 2.5 G Primary 2.5G technologies High Speed Circuit Switched Data (HCSD) General Packet Radio Service (GPRS) Enhanced Data GSM Environment (EDGE) CDMA2000TM Radio Transmission Technology (1xRTT)

  38. High Speed Circuit Switched Data HSCSD is a circuit switched technique Allows an individual user to use consecutive time slots in GSM. HSCSD increases the per time slot data rate from 9.6Kbps to 14.4 Kbps. By using upto four consecutive time slots HSCSD provides a raw data transmission rate upto 57.6Kps

  39. GPRS Unlike HSCSD that dedicates time slots to a user, GPRS supports multi user sharing of its time slots and radio channels Supports many more users than HSCSD but in Bursty manner Adds (defines) new packet channels and switching nodes within the GSM system Provides for theoretical data transmission rates up to 172 Kbps

  40. EDGE An evolved version of GSM Uses 8 levels Phase Shift Keying (8PSK) and packet transmission for advanced high-speed data services Provides for theoretical data transmission rates up to 547.2 Kbps

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