TOBB ETU Bil557 Kablosuz Aglar

1. TOBB ETU Bil557 – Kablosuz Aglar Bahar 2007 Çarsamba 08:30 – 12:00 Sinif: 175 Bülent Tavli Oda: 169 btavli@etu.edu.tr

2. Ders Bilgileri - I Bu derste neler ögrenecegiz? Geleneksel cep telefonu (cellular networks) ve kablosuz aglari (wireless networks) olanakli kilan kavramlar nelerdir? Kablosuz iletisim sistemi tasarimlarindaki temel yapilar ve sistem performansini yükseltme yöntemleri nelerdir? Kablosuz iletisimi konusunda en son asama (state-of-the-art) arastirma nasil yapilir? Bu ders için nasil bir altyapi gerekli? Temel matematiksel analiz Isaret isleme (signal processing) Elektronik iletisim (Telecommunications) Programlama (C/C++ ve Matlab) Eger bu konularda yetersizseniz ? Bu dersi yine de alabilirsiniz Ama ek çaba ve zaman harcamaniz gerekecek Bilgi dagarciginizi genisletmek için ve son derece popüler bir konuda verimli arastirma yapabilmek için mükemmel bir firsat

3. Ders Bilgileri - II Ana kaynak Wireless Communications and Networks, 2nd Edition, Prentice Hall by W. Stallings Bu kitaptan kesinlikle bir tane edinmelisiniz! http://williamstallings.com/Wireless/Wireless2e.html Yardimci kaynaklar Wireless Communications: Principles and Practice , 2nd Edition, Prentice Hall by T. Rappaport Ad Hoc Wireless Networks: Architectures and Protocols, Prentice Hall by C. S. R. Murthy and B. S. Manoj Mobile Ad Hoc Networks: Energy-Efficient Real-Time Data Communications, Springer by B. Tavli and W. B. Heinzelman Derste dagitilacak makaleler ve diger belgeler Network Simulator (ns-2) http://nsnam.isi.edu/nsnam/index.php/User_Information

4. Ders Bilgileri - III Notlandirma Ödevler (iki haftada bir): %20 Proje (rapor + sunum): %30 Arasinav: %25 Sonsinav: %25 Projeler kablosuz iletisim ve aglar hakkinda olmali Derinlemesine literatür taramasi, Benzetim (simulation), Analiz, Uygulama Tek basiniza veya en fazla üç kisilik gruplar halinde Dönem sonunda konferans bildirisi formatinda bir rapor verilecek ve konferans sunumu seklinde bir sunum yapilacak Proje takvimi Subat sonuna kadar projenizi belirleyip onay alin Dönemin son haftasi proje sunumu yapilacak Akademik ahlak Yardimlasmaniz tesvik edilmekle beraber kopye çekmeniz kesinlikle yasaktir

5. Introduction to Wireless Chapter 1

6. What is wireless communication? Any form of communication that does not require the transmitter and receiver to be in physical contact through guided media Electromagnetic wave propagated through free-space Radar, RF, Microwave, IR, Optical Simplex: one-way communication (e.g., radio, TV) Half-duplex: two-way communication but not simultaneous (e.g., push-to-talk radios) Full-duplex: two-way communication (e.g., cellular phones) Frequency-division duplex (FDD) Time-division duplex (TDD): simulated full-duplex

7. Electromagnetic Specturm

8. Why use wireless communication? Provides mobility A user can send and receive messages no matter where he/she is located Added convenience / reduced cost Enables communications without adding expensive infrastructure Can easily setup temporary wireless LANs (disaster situations) Developing nations use cellular telephony rather than laying wires to each home Use resources only when sending or receiving signal

9. Why is wireless different than wired? Noisy, time-varying channel BER varies by orders of magnitude Enviromental conditions affect transmission Shared medium Other users create interference Must develop ways to share the channel Bandwidth is limited TÜK, FCC determines the frequency allocation ISM band for unlicensed spectrum (902-928 MHz, 2.4-2.5 GHz, 5.725-5.875 GHz) Requires intelligent signal processing and communications to make efficient use of limited bandwidth in error-prone environment

10. Early forms of wireless communication Primitive Sound (e.g., beating of drums) Sight (e.g., smoke signals) PA (public address) system Disadvantages of these forms of communication Limited alphabets Noisy Broadcast (no privacy or security) Limited distance (or requires relaying which is unreliable) Require line-of-sight between transmitter and receiver

11. Wireless Comes of Age 1893: Nikola Tesla demonstrated the first ever wireless information transmission in New York City 1897: Marconi demonstrated transmission of radio waves to a ship at sea 29 km away 1915: Wireless telephony established-- VA and Paris 1920's: Radio broadcasting became popular 1930's: TV broadcasting began 1946: First public mobile telephone service in US 1960's: Bell Labs developed cellular concept-- brought mobile telephony to masses 1960’s: Communications satellites launched Late 1970's: IC technology advances enable affordable cellular telephony-- ushers in modern cellular era Early 1990’s: Cellular telephony in Türkiye 2007: ISTCell cellular service is introduced by TürkCell ?

12. Some Milestones in Wireless Communications

13. Modern Cellular Standards First generation (1G) systems (analog) 1979: NTT (Japan), FDMA, FM, 25 kHz channels, 870-940 MHz) 1981: NMT (Sweden and Norway), FDMA, FM, 25 kHz, 450-470 MHz 1983: AMPS (US), FDMA, FM, 30 kHz channels, 824-894 MHz 1985: TACS (Europe), FDMA, FM, 25 kHz channels, 900 MHz Second generation (2G) systems (digital) Supported voice and low-rate data (up to 9.6 kbps) 1990: GSM (Europe), TDMA, GMSK, 200 kHz channels, 890-960 MHz 1991: USDC/IS-54 (US), TDMA, p/4 DQPSK, 30 kHz channels, 824-894 MHz 1993: IS-95 (US), CDMA, BPSK/QPSK, 1.25 MHz channels, 824-894 MHz and 1.8-2.0 GHz 1993: CDPD (US) FHSS GMSK 30 kHz channels 824-894 Mhz Enhanced 2G (2.5G) systems Increased data rates General Packet Radio System (GPRS): packet-based overlay to GSM, up to 171.2 kbps Enhanced Data rates for GSM Evolution (EDGE): modulation enhancements to GSM to support up to 180 kbps 3rd generation (3G) systems Up to 2 Mbps Internet, VoIP 2004-2005: IMT-2000, 2000 MHz range - W-CDMA (UMTS), cdma2000, TD-SCMA

14. Fast facts – Cellular subscribers

15. Fast facts – cellular growth

16. Wireless data standards IEEE 802.11: wireless LAN/ad-hoc networking, 1, 2 or 11 Mbps, DSSS or FHSS with CSMA/CA RTS-CTS-ACK, 2.4 - 2.4835 GHz Bluetooth: replacement for cables, short low power (1 or 100 mW), low cost, 1 piconets with master-slave operation HomeRF: wireless home networking, 150 feet range, up to 10 devices, SWAP protocol IEEE 802.15: wireless PAN, modes for low (< 10 kbps, ZigBee), medium (up to 200 kbps), and high (> 20 Mbps) data rates CDPD: TCP/IP compatible packet transmission via digital overlay to existing analog cellular network, 19.2 kbps PCS: modified cellular protocols, goals--low power, voice and moderate-rate data, small, inexpensive terminals, large coverage area MobileIP: "routing support to permit IP nodes (hosts and routers) using either IPv4 or IPv6 to seamlessly roam among IP subnetworks and media types...maintenance of active TCP connections and UDP port bindings." WAP: communications protocol and application environment, enables viewing of Internet content in special text format on special WAP-enabled devices

17. Underlying concepts Electromagnetics Antennas, wave propagation, channel modeling Signals and systems Filtering, Fourier transforms, block-diagram design Digital signal processing Equalization, spread-spectrum, source coding Communications Modulation, noise analysis, channel capacity, channel coding

18. Enabling Technologies Digital integrated circuits RF generation devices (efficient power amps, sleep modes, improved oscillators, smart antennas) Source coding (data compression) Modulation (improved efficiency) Multiple-access techniques (increase number of users) Channel coding/forward error correction (improve probability of successful reception) Software programmable radios

19. Protocol stack - I Provides abstraction when designing layers We'll discuss each layer in turn...

20. Protocol Stack - II In this slide I’ll draw conclusions form the slides presented so far. MH-TRACE enables traffic adaptive energy efficiency and avoids network partitioning by its transparent clustering algorithm. MH-TRACE throughput is better than that of 802.11. Energy efficiency is better than that of SMAC. Delay is higher, however, the limits of QoS for voice packets are not violated. A framework for routing is created.In this slide I’ll draw conclusions form the slides presented so far. MH-TRACE enables traffic adaptive energy efficiency and avoids network partitioning by its transparent clustering algorithm. MH-TRACE throughput is better than that of 802.11. Energy efficiency is better than that of SMAC. Delay is higher, however, the limits of QoS for voice packets are not violated. A framework for routing is created.

21. Course Outline

22. Part One: Background Provides preview and context for rest of the course Covers basic topics Data Communications TCP/IP

23. Chapter 2: Transmission Fundamentals Basic overview of transmission topics Data communications concepts Includes techniques of analog and digital data transmission Channel capacity Transmission media Multiplexing

24. Chapter 3: Communication Networks Comparison of basic communication network technologies Circuit switching Packet switching Frame relay ATM

25. Chapter 4: Protocols and the TCP/IP Protocol Suite Protocol architecture Overview of TCP/IP Open systems interconnection (OSI) reference model Internetworking

26. Part Two: Wireless Communication Technology Underlying technology of wireless transmission Encoding of analog and digital data for wireless transmission

27. Chapter 5: Antennas and Propagation Principles of radio and microwave Antenna performance Wireless transmission modes Fading

28. Chapter 6: Signal Encoding Techniques Wireless transmission Analog and digital data Analog and digital signals

29. Chapter 7: Spread Spectrum Frequency hopping Direct sequence spread spectrum Code division multiple access (CDMA)

30. Chapter 8: Coding and Error Control Forward error correction (FEC) Using redundancy for error detection Automatic repeat request (ARQ) techniques

31. Part Three: Wireless Networking Examines major types of networks Satellite-based networks Cellular networks Cordless systems Fixed wireless access schemes Use of mobile IP and Wireless Access Protocol (WAP) to provide Internet and Web access

32. Chapter 9: Satellite Communications Geostationary satellites (GEOS) Low-earth orbiting satellites (LEOS) Medium-earth orbiting satellites (MEOS) Capacity allocation

33. Chapter 10: Cellular Wireless Networks Cellular wireless network design issues First generation analog (traditional  mobile telephony service) Second generation digital cellular networks Time-division multiple access (TDMA) Code-division multiple access (CDMA) Third generation networks

34. Chapter 11: Cordless Systems and Wireless Local Loop Cordless systems Wireless local loop (WLL) Sometimes called radio in the loop (RITL) or fixed wireless access (FWA)

35. Chapter 12: Mobile IP and Wireless Access Protocol Modifications to IP protocol to accommodate wireless access to Internet Wireless Application Protocol (WAP) Provides mobile users access to telephony and information services including Internet and Web Includes wireless phones, pagers and personal digital assistants (PDAs)

36. Part Four: Wireless Local Area Networks Examines underlying wireless LAN technology Examines standardized approaches to local wireless networking

37. Chapter 13: Wireless LAN Technology Overview of LANs and wireless LAN technology and applications Transmission techniques of wireless LANs Spread spectrum Narrowband microwave Infrared

38. Chapter 14: IEEE 802.11 Wireless LAN Standard Wireless LAN standards defined by IEEE 802.11 committee

39. Chapter 15: Bluetooth Bluetooth is an open specification for wireless communication and networking Personal computers Mobile phones Other wireless devices

40. Advanced Topics Ad Hoc Networks Sensor Networks

41. Part One Technical Background

42. Transmission Fundamentals Chapter 2

43. Electromagnetic Signal Function of time Can also be expressed as a function of frequency Signal consists of components of different frequencies

44. Time-Domain Concepts Analog signal - signal intensity varies in a smooth fashion over time No breaks or discontinuities in the signal Digital signal - signal intensity maintains a constant level for some period of time and then changes to another constant level Periodic signal - analog or digital signal pattern that repeats over time s(t +T ) = s(t ) -¥< t < +¥ where T is the period of the signal

47. Time-Domain Concepts Aperiodic signal - analog or digital signal pattern that doesn't repeat over time Peak amplitude (A) - maximum value or strength of the signal over time; typically measured in volts Frequency (f ) Rate, in cycles per second, or Hertz (Hz) at which the signal repeats

48. Time-Domain Concepts Period (T ) - amount of time it takes for one repetition of the signal T = 1/f Phase (?) - measure of the relative position in time within a single period of a signal Wavelength (?) - distance occupied by a single cycle of the signal Or, the distance between two points of corresponding phase of two consecutive cycles

49. Sine Wave Parameters General sine wave s(t ) = A sin(2?ft + ?) Figure 2.3 shows the effect of varying each of the three parameters (a) A = 1, f = 1 Hz, ? = 0; thus T = 1s (b) Reduced peak amplitude; A=0.5 (c) Increased frequency; f = 2, thus T = ½ (d) Phase shift; ? = ?/4 radians (45 degrees) note: 2? radians = 360° = 1 period

50. Sine Wave Parameters

51. Time vs. Distance When the horizontal axis is time, as in Figure 2.3, graphs display the value of a signal at a given point in space as a function of time With the horizontal axis in space, graphs display the value of a signal at a given point in time as a function of distance At a particular instant of time, the intensity of the signal varies as a function of distance from the source

52. Frequency-Domain Concepts Fundamental frequency - when all frequency components of a signal are integer multiples of one frequency, it’s referred to as the fundamental frequency Spectrum - range of frequencies that a signal contains Absolute bandwidth - width of the spectrum of a signal Effective bandwidth (or just bandwidth) - narrow band of frequencies that most of the signal’s energy is contained in

53. Frequency-Domain Concepts Any electromagnetic signal can be shown to consist of a collection of periodic analog signals (sine waves) at different amplitudes, frequencies, and phases The period of the total signal is equal to the period of the fundamental frequency

56. Relationship between Data Rate and Bandwidth The greater the bandwidth, the higher the information-carrying capacity Conclusions Any digital waveform will have infinite bandwidth BUT the transmission system will limit the bandwidth that can be transmitted AND, for any given medium, the greater the bandwidth transmitted, the greater the cost HOWEVER, limiting the bandwidth creates distortions

57. Data Communication Terms Data - entities that convey meaning, or information Signals - electric or electromagnetic representations of data Transmission - communication of data by the propagation and processing of signals

58. Examples of Analog and Digital Data Analog Video Audio Digital Text Integers

60. Analog Signals A continuously varying electromagnetic wave that may be propagated over a variety of media, depending on frequency Examples of media: Copper wire media (twisted pair and coaxial cable) Fiber optic cable Atmosphere or space propagation Analog signals can propagate analog and digital data

61. Digital Signals A sequence of voltage pulses that may be transmitted over a copper wire medium Generally cheaper than analog signaling Less susceptible to noise interference Suffer more from attenuation Digital signals can propagate analog and digital data

62. Analog Signaling

63. Digital Signaling

64. Reasons for Choosing Data and Signal Combinations Digital data, digital signal Equipment for encoding is less expensive than digital-to-analog equipment Analog data, digital signal Conversion permits use of modern digital transmission and switching equipment Digital data, analog signal Some transmission media will only propagate analog signals Examples include optical fiber and satellite Analog data, analog signal Analog data easily converted to analog signal

65. Analog Transmission Transmit analog signals without regard to content Attenuation limits length of transmission link Cascaded amplifiers boost signal’s energy for longer distances but cause distortion Analog data can tolerate distortion Introduces errors in digital data

66. Digital Transmission Concerned with the content of the signal Attenuation endangers integrity of data Digital Signal Repeaters achieve greater distance Repeaters recover the signal and retransmit Analog signal carrying digital data Retransmission device recovers the digital data from analog signal Generates new, clean analog signal

68. About Channel Capacity Impairments, such as noise, limit data rate that can be achieved For digital data, to what extent do impairments limit data rate? Channel Capacity – the maximum rate at which data can be transmitted over a given communication path, or channel, under given conditions

69. Concepts Related to Channel Capacity Data rate - rate at which data can be communicated (bps) Bandwidth - the bandwidth of the transmitted signal as constrained by the transmitter and the nature of the transmission medium (Hertz) Noise - average level of noise over the communications path Error rate - rate at which errors occur Error = transmit 1 and receive 0; transmit 0 and receive 1

70. Nyquist Bandwidth For binary signals (two voltage levels) C = 2B With multilevel signaling C = 2B log2 M M = number of discrete signal or voltage levels

71. Signal-to-Noise Ratio Ratio of the power in a signal to the power contained in the noise that’s present at a particular point in the transmission Typically measured at a receiver Signal-to-noise ratio (SNR, or S/N) A high SNR means a high-quality signal, low number of required intermediate repeaters SNR sets upper bound on achievable data rate

72. Shannon Capacity Formula Equation: Represents theoretical maximum that can be achieved In practice, only much lower rates achieved Formula assumes white noise (thermal noise) Impulse noise is not accounted for Attenuation distortion or delay distortion not accounted for

73. Example of Nyquist and Shannon Formulations Spectrum of a channel between 3 MHz and 4 MHz ; SNRdB = 24 dB Using Shannon’s formula

74. Example of Nyquist and Shannon Formulations How many signaling levels are required?

75. Classifications of Transmission Media Transmission Medium Physical path between transmitter and receiver Guided Media Waves are guided along a solid medium E.g., copper twisted pair, copper coaxial cable, optical fiber Unguided Media Provides means of transmission but does not guide electromagnetic signals Usually referred to as wireless transmission E.g., atmosphere, outer space

76. Unguided Media Transmission and reception are achieved by means of an antenna Configurations for wireless transmission Directional Omnidirectional

77. General Frequency Ranges Microwave frequency range 1 GHz to 40 GHz Directional beams possible Suitable for point-to-point transmission Used for satellite communications Radio frequency range 30 MHz to 1 GHz Suitable for omnidirectional applications Infrared frequency range Roughly, 3x1011 to 2x1014 Hz Useful in local point-to-point multipoint applications within confined areas

78. Terrestrial Microwave Description of common microwave antenna Parabolic "dish", 3 m in diameter Fixed rigidly and focuses a narrow beam Achieves line-of-sight transmission to receiving antenna Located at substantial heights above ground level Applications Long haul telecommunications service Short point-to-point links between buildings

79. Satellite Microwave Description of communication satellite Microwave relay station Used to link two or more ground-based microwave transmitter/receivers Receives transmissions on one frequency band (uplink), amplifies or repeats the signal, and transmits it on another frequency (downlink) Applications Television distribution Long-distance telephone transmission Private business networks

80. Broadcast Radio Description of broadcast radio antennas Omnidirectional Antennas not required to be dish-shaped Antennas need not be rigidly mounted to a precise alignment Applications Broadcast radio VHF and part of the UHF band; 30 MHZ to 1GHz Covers FM radio and UHF and VHF television

81. Multiplexing Capacity of transmission medium usually exceeds capacity required for transmission of a single signal Multiplexing - carrying multiple signals on a single medium More efficient use of transmission medium

82. Multiplexing

83. Reasons for Widespread Use of Multiplexing Cost per kbps of transmission facility declines with an increase in the data rate Cost of transmission and receiving equipment declines with increased data rate Most individual data communicating devices require relatively modest data rate support

84. Multiplexing Techniques Frequency-division multiplexing (FDM) Takes advantage of the fact that the useful bandwidth of the medium exceeds the required bandwidth of a given signal Time-division multiplexing (TDM) Takes advantage of the fact that the achievable bit rate of the medium exceeds the required data rate of a digital signal

85. Frequency-division Multiplexing

86. Time-division Multiplexing