Chapter_One_Introduction_to_Wireless_Communication.pptx

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1. W i r e l e ss a nd Mobile C o mm uni c a ti o n Systems Chapter One Overview of W ireless Communication By : Hiwot B . 1

2. Goals of the Chapter To give an overview on what and why wireless communication Assess impact of wireless communication in our daily life Define basic terminologies , historic perspectives and evolution of wireless communication 2

3. O verview Basic principles of wireless communications History of wireless communication systems Types and Examples of wireless communication systems Trends in cellular radio communication systems 3

4. Used Acronyms ETSI : European telecommunication standard institute IMT: International mobile telecommunication DECT : Digital enhanced cordless telecommunication HSCSD : High speed circuit switched data GPRS: General packet radio service FOMA : Freedom of mobile multimedia access PCS: Personal Communication Services PDA : Personal digital assistant PDC: Personal digital cellular PSTN: Public Switched Telephone Network GEO: Geosynchronous satellite GPS : Global positioning systems LEO: Low earth orbit satellite UMTS: Universal mobile telecommunication systems ISM: Industrial, Scientific and Medical WiMAX: Wireless Interoperability for Microwave Access 4

5. Class Activity Define wireless communication system and Explain the advantage and disadvantage of wireless communication 5

6. Basic Principles of Wireless Communications Transfer of information (voice, data, multimedia) over a distance without the use of electrical wires Distances involved may be Short: e.g., remote control or Bluetooth Long: e.g., satellite communication Information is transmitted using electromagnetic waves(EMW) Suitable frequencies are: Case of Ethiopia ISM bands 6

7. 7 Is a broadcast medium Multiple access methods are required Transmissions are prone to interference Wireless channel is unpredictable: e.g., multipath, mobility System design is more challenging in wireless than in wired communication Additional channel optimization techniques are required. Adaptive modulation and equalization Coding and diversity

8. Wired Vs Wireless Networks 8 Attenuation is low Interference is nil: each wire is a separate medium/channel Clumsy, costly, no mobility Delay in new connections Security Hazards Prone to failures (line disconnection) Attenuation is high Interference is high (co- and adjacent channel, from engines, lightning, fading due to movement ) No knots, no digging to lay cables, tether free Mobility

9. Merits of Wireless Communication Freedom from wires No cost of installing wires or rewiring No bunches of wires running here and there Instantaneous communication without the need for physical connection setup (Bluetooth, Wi-Fi, WiMAX) These reasons drive the market …. Various emerging standards….IEEE 802.11,.15,.16,.20 9

10. Global coverage Communications can reach where wiring is infeasible or costly: rural areas, old buildings, battle fields, outer spaces, vehicular communications. Wireless Ad-hoc Networks Wireless Sensor Networks Stay connected Roaming: allows flexibility to stay connected anywhere and anytime Rapidly growing market shows to public need for mobility and uninterrupted access 10

11. Flexibility Stay connected: Anyone , anywhere, anytime! Services reach you wherever you go (mobility) You don’t have to go to the lab to check your mail Connect to multiple devices simultaneously (no need for physical connectivity) Increas i ng dependence on t e l eco mm un i ca ti on serv i ces f or business and personal reasons Consumers and businesses are willing to pay for it 11

12. Challenges of Wireless Communication Bandwidth Scares spectrum and dictates low data rates Efficient use of finite radio spectrum E.g., cellular frequency reuse, medium access control protocols, MIMO systems instead of single TX/RX antenna systems Reliability Low data rate because of interference Need interference minimizing or mitigating techniques 12

13. 13 Power Management Mobility brings about battery operation Need efficient hardware, e.g., low power transmitters, receivers, and signal processing tools Saving options: Sleep mode in sensor networks Security Shared/broadcast medium => low security Privacy and authentication needed

14. Providing integrated services: Consumer side challenges Voice , data, multimedia over a single network Service differentiation, priorities, resource scheduling required One size fits of all protocols and designs do not work well 14

15. 15 Network supports user mobility User location identification Handover analysis Impact of wireless channels: Fading & Doppler Multipath leads to signal superposition at receiving antennas High probability of data corruption: need for diversity schemes Quality of service (QoS) Unreliable links Traffic patterns and network conditions constantly change

16. Connectivity and coverage Local networking Internetworking Regulatory issues Spectral allocation/regulation heavily impacts the evolution of wireless technologies Worldwide spectrum controlled by ITU-R ITU auctions spectral blocks for set of applications Some spectrum set aside for universal use Cost & efficiency, ….. 16

17. Frequencies for Communication VLF = Very Low Frequency LF = Low Frequency MF = Medium Frequency HF = High Frequency VHF = Very High Frequency UHF = Ultra High Frequency SHF = Super High Frequency EHF = Extra High Frequency UV = Ultraviolet Light 1 Mm 300 Hz 10 km 30 kHz 100 m 3 MHz 1 m 300 MHz 10 mm 30 GHz 100  m 3 THz 1  m 300 THz V LF LF MF H F VH F UH F SH F EH F infra re d visible light UV optical transmission coax cable t w isted pair Basic property of electromagnetic waves: speed c = 3x10 8 m/s Frequency f and wave length  :  = c/f 17

18. Frequencies for Communication… 1 4 1 2 1 1 - 2 1 - 4 1 - 6 1 - 8 1 -10 1 -12 1 -14 1 -16 1 4 1 6 1 8 1 1 1 1 2 1 1 4 1 1 6 1 1 8 1 2 1 2 2 1 24 < 30 KHz 30-3 00KH z 300KHz – 3MHz 3 MHz – 30MHz 30MHz – 300MHz 300 MHz – 3GHz 3-30GHz > 30 GHz 18 V LF LF MF HF VH F UHF SH F EH F Radio S p ectrum M icro w ave IR UV X-Rays C os m ic Rays Visible light

19. Which Frequency? 19 What constitutes a good frequency for wireless communication? Suitable for various environments Indoor, outdoor Penetration of walls, circumvention of obstacles Susceptibility to environmental conditions E.g., weather (rainfall, fog) Different frequencies attenuated differently The higher frequency range, the better the BW available but the more the attenuation As frequency increases, wavelength decreases

20. Which Frequency? … 20 Complexity of circuitry and antenna size Circuit design at high frequency is challenging Energy consumption of transmit/receive circuits Regulatory aspects and money paid to get license Some frequencies are reserved for specific usage, some are free Available bandwidth The more the money, the longer it takes for the operators’ return Slows down rate of new technology introduction E.g., Total Cost of 3G Licenses in Europe 110bn Euros

21. History of Wireless Communication Systems Electromagnetic waves are of special importance: 1831 Faraday demonstrated electromagnetic induction J. Maxwell (1831-79): theory of electromagnetic fields, wave equations (1864 ) H. Hertz (1857-94): experimentally demonstrated the wave character of electrical transmission through space 21

22. 22 1895: Guglielmo Marconi First demonstration of wireless telegraphy (digital!) Long wave transmission, high transmission power necessary (> 200kw) 1907 : Commercial transatlantic connections huge base stations (30 antennas, each 100m high) 1915: Wireless voice transmission between New York and San Francisco (needs huge antenna & transmission power ~200KW) 1920: Discovery of short waves by Marconi Send short radio wave by reflection at the ionosphere (60-1000km altitude) smaller sender and receiver, possible due to the invention of the vacuum tube (1906, Lee DeForest and Robert von Lieben)

23. 23 1928 : Many TV broadcast trials (across Atlantic, color TV, TV news ) 1933 : Frequency modulation (FM) introduced by E. H. Armstrong FM has been the primary modulation technique for mobile communication systems until late 80 1982: Start of GSM-specification Goal: Pan-European digital mobile phone system with roaming

24. 24 1983: Start of the American AMPS (Advanced Mobile Phone System, analog ) , i.e. First cellular telephone system 1991: Specification of DECT Digital European Cordless Telephone (today: Digital Enhanced Cordless Telecommunications) 1880-1900MHz, ~100-500m range, 120 duplex channels, TDMA, 1.2Mbit/s data transmission, voice encryption, authentication, up to several 10000 user/km 2 , used in more than 50 countries.

25. 25 1992: Start of GSM F ully digital, 900MHz, 124 channels Automatic location, hand-over, cellular Roaming: in Europe - now worldwide in more than 170 countries Services: data with 9.6kbit/s, FAX, voice, ...

26. 1997: Wireless LAN - IEEE802.11 IEEE standard, 2.4 - 2.5GHz and infrared, 2Mbit/s Already many (proprietary) products available in the beginning 1998: Specification of GSM successors For UMTS (Universal Mobile Telecommunication System) as European proposals for IMT-2000 1999 : Standardization of additional wireless LANs IEEE standard 802.11b, 2.4-2.5GHz, 11Mbit/s Bluetooth for piconets, 2.4Ghz, <1Mbit/s 26

27. 27 1999: Decision about IMT-2000 Several members of the family: UMTS, cdma2000, DECT 1999: Start of WAP (Wireless Application Protocol) and i-mode First step towards a unified Internet/mobile communication system Access to many services via the mobile phone 2000 : GSM with higher data rates up to 57.6kbit/s First General Packet Radio Service ( GPRS ) trials with up to 50 kbit/s (packet oriented!)

28. 28 2000: UMTS auctions/beauty contests Hype followed by disillusionment (approx. 50 B$ payed in Germany for 6 UMTS licences) 2001: Start of 3G systems CDMA 2000 in Korea, UMTS in Europe, F OMA (almost UMTS) in Japan 2005: Broadband wireless First public WiMAX/IEEE 802.16 last mile experiments 2008: Release of HSPA 337 Mbit/s in the downlink and 34 Mbit/s in the uplink.2005: Broadband wireless

29. 29 200 9 : 4G/LTE Applications include: Amended mobile web   access IP telephony Gaming services , High-definition mobile TV, Video conferencing, and 3D television 20 13 : LTE-Advanced 1000Mbits/s downlink, 500Mbit/s uplink 20 20 : 5G Deployment (expected) Now underdevelopment

30. Types and examples of wireless communication Types of Wireless Communication Radio Transmission (3KHz-300GHz) E as il y genera t ed, O m n i -d i rec ti ona l l y t ravel l ong d i s t ances Easily penetrate buildings Problems Frequency dependent Relatively low-bandwidth for data communication Tightly licensed by governments 30

31. 31 Microwave Transmission ( λ =1m-1mm) Widely used for long distance communication Give higher SNR Relatively inexpensive Problems Don’t pass through building well: LOS communication Weather and frequency dependent In Radar : The short wavelength of microwaves causes large reflections from objects the size of motor vehicles, ships and aircraft to identify location, range, speed, and other characteristics of the object to be determined. 

32. 32 Infrared and Millimetre Wave Transmission Widely used for millimeter waves (can be used for high-speed wireless broadband communications. ) : above 30 GHz Unable to pass through solid objects Used for indoor Wireless LANs, not for outdoors: 10m range May need a production of new devices

33. 33 Light Wave Transmission ( λ = 400–700   nm) optical signal such as laser Unidirectional, easy to install, don’t require license Connect two LANs in two buildings via laser mounted on the roofs Has better bandwidth Problems Unable to penetrate rain or thick fog Laser beam can be easily diverted by windy/stormy air

34. 34 WLL: Wireless Local Loop : use of a wireless communications link for delivering   broadband Internet access to telecommunications customers. 

35. Examples of Wireless Networking 1. Cellular systems : Architecture 35

36. 36 Geographic region divided into cells Frequency/timeslots/codes are reused at spatially separated locations Co-channel interference between same frequency using cells Shrinking /reducing cell size increases capacity as well as networking burden Cell edges are determined based on Link budget : total power emitted and received Number of users Interference: dictates re-use factor Handoff

37. 37 Basic Terminologies: Mobile station (MS) A station in the cellular radio service intended for use while in motion at unspecified locations They can be either hand-held personal units (portables) or installed on vehicles (mobiles) Base Station (BS) A fixed station in a mobile radio system used for radio communication with the mobile stations BSs are located at the centre or edge of a coverage region , consists of transmitter and receiver antennas , and are mounted on top of towers Provides gateway functionality between wireless and wired links BSs coordinate handoff and control functions

38. Mobile Switching Center (MSC) Switching center which coordinates the routing of calls in a large service area In a cellular radio system, the MSC connects the BS and MS to the PSTN (telephone network) o Mobile Telephone Switching Office (MTSO) Subscriber A user who pays subscription charges for using a mobile communication system Transceiver A device capable of simultaneously transmitting and receiving radio signals 38

39. 39 Handoff/ Handover The process of transferring a mobile station from one channel or base station to another Roamer A mobile station which operates in a service area (market) other than that from which service has been subscribed Page A brief message which is broadcast over the entire service area, usually in simulcast (broadcast) fashion by many base stations at the same time

40. Channel types Control (forward and reverse) channel : Radio channel used for transmission of call setup, call request, call initiation and other beacon and control purposes Downlink (forward) voice channel: Radio channel used for transmission of information from the base station to the mobile Uplink (reverse) voice channel: Radio channel used for transmission of information from mobile to base station 40

41. 41 Duplexing and Multiplexing Techniques The information from sender to receiver is carried over a well- defined frequency band This is called a channel Each channel has a fixed frequency bandwidth and capacity (bit- rate) Different frequency bands (channels) can be used to transmit information in parallel and independently Duplexing and multiplexing techniques are required

42. 42 Duplexing Given a single pair of communicating peers, duplexing describes rules when each peer is allowed to send to the other one Using the resources like : FDD, TDD Multiplexing Given several pairs , multiplexing describes when which pair , using which resources (eg. TDMA, FDMA, CDMA ), is allowed to communicate Main resources: Time, frequency, (+ some others)

43. 43 Duplexing Types for Cellular Systems Simplex, half- and full-duplex variants of duplexing Simplex: Is a one way communication, i.e., one source transmits and the other only receives Example: remote control, radio broadcast To enable two-way communication, we can use Frequency as in FDD or Time as in TDD

44. Half duplex systems Communication systems which allow two-way communication by using the same radio channel for both transmission and reception one at a time At any given time, the user can either transmit or receive information Use one frequency band but peers transmit one after the other, called TDD 44

45. Full Duplex Systems Communication systems which allow simultaneous two-way communication Transmission and reception is typically on two different channels (FDD) Downlink and uplink channels use different frequency bands. Providing two simultaneous but separate channels to both users by using FDD or TDD 45

46. Frequency Division Duplexing (FDD): Supports two way communication with two distinct radio channels. One channel is transmitted downstream from the BS to the MS. The second is used in the upstream direction and supports transmission from the MS to the BS. Hence simultaneous transmission in both directions is possible. To mitigate self-interference between upstream and downstream transmissions, a minimum amount of frequency separation must be maintained between the frequency pair. 46

47. Time Division Duplexing (TDD): TDD uses a single frequency band to transmit signals in both downstream and upstream directions. TDD operates by toggling transmission directions over a time interval. This toggling takes place very rapidly and is imperceptible to the user . 47

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49. Multiplexing Used for sharing radio resources Multiplexing: Gives a means to regulate access to a resource that is shared by multiple users The switching element that serves as a controller Main resources to be shared Time, frequency, (+some others) Techniques TDMA, FDMA, SDMA, CDMA 49

50. 2. Paging Systems Broad coverage for short, low rate, one way messaging Message broadcast from base stations to highly mobile users. Simple terminals Low complexity, very low powered pagers (receiver) devices Optimized for one way transmission Answer-back hard Overtaken by cellular 50

51. 3. Personal Area Networks ( PANs) Network of devices carried by an individual person Music player, cell phone, laptops .... Networks that connect devices within a small range Typically on the order of 10-100 meters Zegbee (low power and data rate close proximity (personal area) protocols for home automation, medical device data collection), Bluetooth, … Application areas Data and voice access points Real-time voice and data transmissions Cable replacement Eliminates need for numerous cable attachments Ad-hoc networking Device with PAN radio can establish connection with another when in range 46

52. Wireless Personal Area Networks(PANs) Cable replacement RF technology (low cost) Short range (10m, extendable to 100m) Operates in the unlicensed 2.4 GHz ISM band Widely supported by telecommunications, PC, and consumer electronics companies Provides an ad-hoc (direct communication) approach to enable various devices to communicate. 52

53. Wireless Local Area Networks (WLANs) Network between devices in close physical proximity (offices, homes, …), usually stationary or moving at low speed , provide access to fixed infrastructure Good options for coffee shops, airports, libraries to provide internet connection (connect “local” computers in 100m range) The term Wi-Fi is widely used 53

54. Channel access is shared (random access) WLANs provide license-free, low-power short-range data communication 54

55. WLAN Standards 55 802.11b Standard for 2.4GHz ISM band Direct sequence spread spectrum (DSSS ) : (Spreading a message signal to gain wider bandwidth) Data Rate: 5.5 - 11 Mbps for approximately 100 m range 802.11a/g Standard for 5GHz band /also 2.4GHz OFDM in 20 MHz with adaptive rate/codes Data rate: 54 Mbps for approximately 100 m range

56. 56 802.11n Standard in 2.4 GHz and 5 GHz bands Adaptive OFDM/MIMO in 20/40 MHz (2-4 antennas) Data rate up to 600Mbps for approximately in 100 m range Other advances in packetization , antenna use, etc.

57. 802.11 WLAN standards summary 57

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59. Wireless Metropolitan Area Networks (WMANs) Network covering a city, metropolitan areas “Last mile” application, usually at best low mobility Technologies Various IEEE 802.11 (WLAN) derivates Integration of fixed and mobile systems WiMAX: Worldwide Interoperability for Microwave Access WiMAX/IEEE 802.16: competes with DSL IEEE 802.20 ( Broadband ) 59

60. Wide Area Networks( WAN ) : Network covering country/continent/earth Anytime, anywhere connectivity Good for even highly mobile users Technologies Cellular systems (GSM, UMTS , HSDPA , .. ) Broadcast systems (DVB) Satellites systems 60

61. 61 4. Satellite Communication Systems Cover very large areas Very useful in sparsely populated areas, rural areas, sea, mountain areas Has different orbit heights Geo stationary orbit ( GEOs ) (36000 Km) versus (Low Earth Orbits) LEOs (2000 Km) Optimized for one way transmission(Licence required to transmit) Radio and movie broadcasts

62. 62 Expensive base stations (satellite) Moving base stations unlike the cellular system Traditional Applications Weather satellite, Radio and TV broadcasting, Military satellite Telecommunication applications Global telephone connections, Backbone for global networks, Global Positioning System ( GPS ) , i.e. satellite signals used to point location Iridium, Globalstar, Teledesic, Inmarsat: Are examples of LEO satellite constellation for satellite phone and data communications

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64. 64 Emerging Wireless Networks Ad-hoc Wireless Systems Wireless Sensor Networks Ultra Wideband (UWB) Systems Cognitive and Software Radio systems RFID Systems

65. Mobile Ad-Hoc Networks( MANETs ) 65 Peer to peer communication without backbone infrastructure Topology is dynamic Fully connected with different links SINRs Example scenarios for MANETs Meetings Emergency or disaster relief situations Military communications Wearable computers ( Smartphones , wristwatches,…) Sensor networks

66. 66 Ad-hoc networks provide a flexible network infrastructure for many emerging applications Transmission, access, and routing strategies for these networks are generally ad-hoc Energy constraints impose interesting design tradeoffs for communication and networking Energy efficient routing protocol design

67. Ad-hoc network representation 67

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69. Wireless Sensor Networks (WSN) 69 Wireless Sensor Networks (WSNs) are: A self-configuring , highly distributed network of lightweight sensor nodes communicating among themselves using radio signals Deployed in large numbers to sense, monitor and understand the physical world. Monitors the environment or system by measuring physical parameters such as temperature, pressure, humidity. Provide a bridge between a real physical and virtual world.

70. Example system architecture of WSN 64

71. WSN characteristics Nodes powered by non-rechargeable batteries Data flows to central base station location Low per-node rates but up to 100,000 nodes Data highly correlated in time and space Nodes can cooperate in transmission, reception, compression, and signal processing Standards: 802.15.4 and ZigBee They are low-power protocols Performance is an issue Maximum distance is around 100 m 71

72. Ultra Wide Band (UWB) Systems An emerging wireless communication technology that can transmit data from100 Mb/s to 1000 Mb/s UWB transmits ultra-low power radio signals with very narrow pulses (in nanoseconds) Because of its low power requirements, UWB is very difficult to detect ( hence secure ) 72

73. Why UWB ? Exceptional multi-path immunity Low power consumption Large bandwidth Secure communication Low interference No need for license to operate 73

74. Trends in Cellular Radio Communication Systems 74

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78. First Generation (1G) Analog systems, mostly FM NMT, AMPS Voice traffic FDMA/FDD multiple access Second Generation (2G) Digital systems Digital modulation Voice traffic TDMA/FDD and CDMA/FDD multiple access 78