Digital Cellular Technologies


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Digital Cellular Technologies

  1. 1. An Overview ‘Digital Cellular Network Technologies’ Presented by Prof. T. L. SingalNational-Level Faculty Development Workshop“Challenges for Research in Wireless Communication Technologies”May 21-23, 2012Chitkara University, Punjab 1
  2. 2. Evolution of CellularGenerations – A Recap 2
  3. 3. Cellular Network Generations• 1G: First Generation Analog Cellular System - Analog voice• 2G: First Digital Cellular System - Digital voice and messaging• 2.5 G: Digital Cellular System - Increase in digital data rates• 3G: Digital Cellular System with increase in functionality - Broadband data and Voice over IP• 4G: Future re-architecting of digital cellular infrastructure - Increased data throughput 3
  4. 4. Examples of 1G and 2G• First Generation Cellular Networks (1G) – Analog systems based on FDMA (e.g. AMPS, NMT, UK-TACS)• Second Generation Cellular Networks (2G) – Digital systems based on TDMA and CDMA (e.g. GSM, TIA/EIA-136, IS-95)• Second Generation+ Cellular Networks (2.5G) – Digital systems based on TDMA and CDMA with higher data rate capabilities (e.g. GPRS, cdma2000) 4
  5. 5. Advantages/Disadvantages - 1G and 2G Networks• First Generation Cellular Networks (1G) – Spotty coverage• Second Generation Wireless (2G) – Improved voice quality – Limited low-speed, circuit-switched data capabilities• Second Generation Wireless + (2.5G) – Introduction of packet data – Higher data rates (up to 144 kbps) 5
  6. 6. 3G and 4G• Third Generation Cellular Networks (3G) – Digital systems based on TDMA (GSM) and CDMA with data rate capability upto 2 Mbps (e.g. WCDMA/UMTS, cdma2000, UWC-136)• Fourth Generation Cellular Networks (4G) – Digital systems based on OFDMA and MC-CDMA with higher data rate capability for advanced multimedia applications. 6
  7. 7. Evolution of Cellular Networks Fourth Generation 7
  8. 8. Key Parameters 8
  9. 9. Paradigm shift - 1G towards 4G Fourth Generation 9
  10. 10. Comparison of 1G to 4G SystemsGeneration 1G 2G 3G 4G OFDMA, MC-CDMA 10
  11. 11. GSM and CDMA 11
  12. 12. Multiple Access Technologies 12
  13. 13. GSM - FDMA and TDMA Time 7 6Amplitude 5 4 time slot number 3 2 1 0 Frequency 1 2 3 4 5 6 ARFCN 13
  14. 14. Structure of a GSM SignalGSM carriers are spaced 200KHz apart.In the BTS downlink signal,different timeslots belong todifferent users - a mobilelistens only to its recurringtimeslots.The mobile on its uplinktransmits only during itsassigned timeslots. 14
  15. 15. GSM Network Areas PLMN service area MSC/VLR service areas Location Areas Cells 15
  16. 16. GSM Cell Plan 16
  17. 17. GSM Network Architecture NMC BTS OMC OMC BTS BSC BTSM VLR BSS MSCS MSC EIR BTS AuC BTS BSC VLRMS MSC BTS MSC HLR BSS Interface to other networks 17
  18. 18. A Typical GSM System 18
  19. 19. Advantages/Disadvantages - GSM Network• Advantages – Can provide roaming services – Reduces probability of total corruption of speech – Offers standard protocols between components• Disadvantages – Limited data rate capability – Macrocells affected by multipath signal loss – Low Capacity 19
  20. 20. GSM Networks Future Trends WCDMA <470 kbps Evolution 384 - 2048 kbps EDGE EGPRS GPRS WCDMA HSCSD 9 - 53.6 kbps Phase I 144 - 384 kbps GSM 9.6 - 28.8 kbps Data 9.6 kbps 1999 2000 2001 2002 2003-2005 20
  21. 21. What is CDMA?Code Division Multiple Access CDMA is a spread spectrum system and is directly related to the number of users accessing the system. CDMA system allow one-cell frequency reuse and all users use the entire carrier, all the time. Each user is distinguished by a Direct Sequence Code during a call. 21
  22. 22. CDMA: Using A New Dimension 22
  23. 23. CDMA is a Spread- Spectrum System 23
  24. 24. CDMA Cell Plan 1 1 11 1 1 1 1 1 24
  25. 25. CDMA Network Architecture BTS OS BTS BSC BTSMS VLR BS MSC MSC EIR BTS AuC BTS BSC VLRMS MSC BTS MSC HLR BS Interface to other networks 25
  26. 26. CDMA - Advantages• Easy frequency planning (Frequency reuse of one)• Greater coverage with fewer cells• High capacity without hard blocking limits• Excellent call quality (supports soft handoff)• Inherent privacy due to unique user codes• Lower power transmission• Longer battery life• Tight power control• Technology platform extendable to new services• Providing reliable transport mechanism for data communications, such as facsimile and internet traffic 26
  27. 27. CDMA - Advantages contd… Dramatically improving the telephone traffic capacity. Significantly improving the voice quality and eliminating the audible effects of multipath fading. Reducing the incidence of dropped calls due to handoff failures. Reducing the number of sites needed to support any given amount of traffic. Simplifying site selection, thus reducing deployment and operating costs because fewer cell sites are needed. Reducing average transmitted power, thereby reducing interference. 27
  28. 28. Capacity Comparisons – GSM and CDMAGSM Capacity limit is fixed CDMA Capacity limit isat 8 x number of ARFCNs „soft‟, Increases withper cell decrease in quality. Typically 4-5 times that of a GSM system. 28
  29. 29. GSMArchitecture 29
  30. 30. 30
  31. 31. 31
  32. 32. 2G+ Cellular Network 32
  33. 33. 3G Market Drivers 33
  34. 34. How Do Operators Get to 3G? 34
  35. 35. 3G air interface technologiesWCDMA/UMTS cdma2000 UWC-136CDMA-based CDMA-based TDMA-basedDirect sequence Multi-carrier --Evolution of GSM Evolution of Evolution of IS-95 TDMARequires new Could be Could bespectrum deployed in deployed in existing spectrum existing spectrum 35
  36. 36. GPRS Architecture 36
  37. 37. Example for packet routing in GPRS 37
  38. 38. Example of GPRS Internet Connection 38
  39. 39. The GSM Technology Path to 3G 39
  40. 40. 3 Steps to 3G:The GSM Network Transition 40
  41. 41. Global TDMA Convergence Mobility Gateway ANSI-136 GSM Network Network TCP/IP Network IW ANSI-41 IW MAPANSI-136 EGPRS GSM UWC-136/EDGE
  42. 42. The CDMA Technology Path to 3G 42
  43. 43. 3G Network Architecture 43
  44. 44. Advantages – The 3G Network• Common worldwide spectrum• Global seamless roaming• Multimedia services on the mobile internet• Flexible, spectrum-efficient network• Enhanced security and performance• Wireline services and quality levels• Rapid introduction of new technology 44
  45. 45. Disadvantages – The 3G Network• Insufficient bandwidth• Service differentiation• IP translators are the wrong application andservice model (e.g., WAP, imode, etc.)• Wrong architectural model for IP data 45
  46. 46. KEY APPLICATIONS• Current: ~10 kb/s, circuit/packet – Fax – Short-messaging – Being evolved to ~50-100 kb/s peak rate• Needed to make wireless data attractive: – Web Browsing - downlink bandwidth hungry – FTP or Emails with file attachment - both links• 3G: “Multimedia,” mainly packet – Wide-area, low mobility, 384 kb/s – Wide-area, high mobility, 144 kb/s – Indoor, 2 Mb/s• Beyond 3G ?
  47. 47. Radio Technology Evolution• High Speed Services – Nominal Rates: • At least 144 kbps macrocell • At least 384 kbps outdoor pedestrian • At least 2 Mbps indoor • => 1-2 Mbps or higher in macrocell – Support emerging IP-based services • Real-time and non real-time – Optimized for packet-switched operation • Support appropriate QoS definitions • Data and multimedia services
  48. 48. Technology Evolution to IMT- 2000 Radio Access Existing New EDGE/GPRS SpectrumSpectrum IMT-2000 GSM GSM+ Systems GPRS UMTS/ PDC W-CDMA TDMA TDMA UWC-136 HS (EDGE) ?(IS-136) IS-136+ ?CDMA CDMA 3G-1X cdma2000(IS-95)
  49. 49. Deployment Scenario Edge SGSN WCDMA GPRS backbone SGSN GGSN BG BG GGSN GPRS Inter- backbone operator GGSN GPRS SGSN GGSNEdge router Public Internet router server router Backbone
  50. 50. Wireless Data Terminals NokiaSierra PCMCIA Nokia 9110 The new 3G visionCDPD Modem Ericsson R380 phone, which features wireless data functions
  51. 51. Looking to the Future….4G and Beyond 51
  52. 52. 52
  53. 53. Transition from 3G to 4G …. 53
  54. 54. Positions and Challenges for 4G• Wireless Data is king – Direction: design for data and IP - not voice circuits• Wide variety of wireless link technologies; 2G/3G,wireless LAN, MANETs, PANs, wireless sensor networks;new radio 4G technologies will emerge – Direction: IP over every radio link• Multitude of mobile devices; sensors, watches, pagers,pocket PCs, etc. – Direction: IP on every mobile device 54
  55. 55. Key Elements of 4G Vision 55
  56. 56. • Fully converged servicesPersonal communications, information systems, broadcast,entertainment and a wider range of services available conveniently,securely and in a manner reflecting the user’s personal preferences.• Ubiquitous mobile accessThe dominant mode of access will be mobile, accounting for fullyconverged services, including mobile access to commercial andretail services.• Diverse user devicesThe user will be served by a wide variety of low-cost mobile devicesto access content conveniently and seamlessly. Devices will interactwith users in a multi-sensory manner. 56
  57. 57. • Autonomous networks4G systems will be highly autonomous adaptive networks capable ofself-management of their structure to meet users’ changing andevolving demands, for both services and capacity. Efficient and cost-effective use of the radio spectrum will be an essential element of theiroperation.• Software dependencyIntelligent Mobile Agents will exist throughout the networks and inuser devices, acting continually to simplify tasks and ensuretransparency to the user. These Mobile Agents will act at all levels,from managing an individual user’s content preferences, to organizingand reconfiguring major elements of networks. 57
  58. 58. Advantages - The 4G Network• Improved Spectral Efficiency• Improved quality of service• Increased data throughput• Broadcast and Cellular Network Convergence• Adaptive and Reconfigurable Systems• Advanced Antenna Technologies• Creation of new business models for operators 58
  59. 59. 4G Network Architecture 59
  60. 60. 4G Network Scenario 60
  61. 61. 4G Network Connectivity 61
  62. 62. Vision of Beyond 4G 62
  63. 63. Evolution from voice-only to multimedia mobile services 63
  64. 64. Ultimate Goal – Maximum Data Rate 64
  65. 65. T. L. Singal graduated from National Institute of Technology, Kurukshetra in 1981 . He began his illustrious career with Avionics Design Bureau at HAL, Hyderabad and worked on design and development of Air-Route Surveillance Radar Communication System. Then he led R&D group in a Telecom company and successfully developed Multi-Access Wireless Communication Systems.He executed international assignment as Senior Network Consultant with Flextronics International Inc. USA during 2000-02. He was associated with Nokia, AT&T, Cingular Wireless and Nortel Networks, for optimization of 2G/3G Cellular Networks in USA. Since 2003, he is in teaching profession in engineering colleges in India. He has number of technical research papers published in the IEEE Proceedings, Journals, and International/National Conferences. He has authored two text-books `Wireless Communications’ and `Analog & Digital Communications’, published by renowned publisher Tata McGraw-Hill. 65
  66. 66. ReferencesT L Singal, Wireless Communications, ISBN: 978-0-07-068178-1, Tata McGraw-Hill, First Edition, 2010. 66
  67. 67. Queries? No: +91-98145-42041 67
  68. 68. 68
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