Lecture 1 Introduction to Wireless Communication Systems.pdf
- 1. Mobile Communication Systems Introduction to Wireless Communication Systems Lecturer: Dr. Eman Siraj El-Din Email : emansiraj@aucegypt.edu Reference: T. S. Rappaport, "Wireless Communications: Principles & Practice", Second Edition, Prentice Hall, 2002. Chapter 1&2.
- 2. Course Instructional Goals ◼ Build an understanding of fundamental components of wireless communications. ◼ Investigate the wireless communication channel characteristics and modeling. ◼ Discuss different access techniques to the shared broadcast wireless medium. ◼ Highlight measures of performance and capacity evaluation of Mobile wireless communication systems. ◼ Know the tradeoffs that influence the design and evolution, network dimensioning, and capacity planning of digital wireless systems. ◼ Know how a cellular phone works, as well as the functions of its various components in the fixed portion of the network. ◼ Understand the differences between analog and digital cellular systems. ◼ Provide an insight to different practical Mobile wireless communication systems: Definition and history of generations of wireless systems:1G, 2G, 2.5G & 3G, and understand the paths to third-generation (3G) system. ◼ 3GPP data services HSPA/LTE ◼ WiFi and Wireless LANs ◼ WiMax and Wireless Local Loop ◼ Bluetooth and Zigbee 2
- 3. Text Book and References Text Book: ◼ “Wireless Communications: Principles and Practice “, 2nd Edition”, T. S. Rappaport, Prentice Hall, 2002 Reference Books: ◼ “Wireless Communications”, A. Molisch, Wiley- IEEE Press, 2005 ◼ “Modern Wireless Communications”, S. Haykin and, M. Moher, Prentice Hall, 2004 ◼ “Mobile Wireless Communications”, M. Schwartz Cambridge University Press, 2005
- 4. Networking Role, Components, and Challenges ◼ Describe the various elements that make up a network – Devices • These are used to communicate with one another – Medium • This is how the devices are connected together – Messages • Information that travels over the medium – Rules • Governs how messages flow across network
- 5. Networking Role, Components, and Challenges ◼ Describe the role of converged networks in communications – Converged network • A type of network that can carry voice, video & data over the same network
- 6. Traffic Requirements Voice Video Data Delay Packet Loss BER Data Rate Traffic <100ms - <100ms <1% 0 <1% 10-3 10-6 10-6 8-32 Kbps 1-100 Mbps 1-20 Mbps Continuous Bursty Continuous 6
- 7. 1.7 Data flow (simplex, half-duplex, and full-duplex) Introduction
- 8. Introduction • Wireless means communication by radio. Why go wireless ? • Wireless affords mobility, portability, Cost and ease of connectivity.( no cable limitation & restrictions) ▪ Target information systems 3A: communication ▪ “Anytime, Anywhere, Any form”. 8
- 9. Wireless Challenges ◼ Wireless channel is an unpredictable, difficult and capacity-limited broadcast communications medium. ◼ Radio spectrum is a scarce resource, and can be very expensive. It must be used extremely efficiently. ◼ Traffic patterns, user locations, and network conditions are usually changing. ◼ Applications are heterogeneous with hard constraints that must be met by the network. ◼ Energy (power) and delay constraints change design principles. ◼ Security is difficult to implement. ◼ Wireless networking issue (seamless connectivity). ◼ Interfacing between wireless and wired networks with different performance capabilities is a difficult task. ◼ Cross-layer design and optimization is challenging. 9
- 10. Wireless & Mobility ◼ Challenges in Mobile Computing : Three major challenges: ◼ Wireless Channel ◼ Mobility ◼ Device Limitation Wireless: Limited bandwidth Broadcast medium: requires multiple access schemes Variable link quality (noise, interference) High latency, higher jitter Heterogeneous air interfaces Security: easier snooping Mobility: User location may change with time Speed of mobile impacts wireless bandwidth Need mechanism for handoff Security: easier spoofing Portability Limited battery, storage, computing, and UI 10
- 11. Design ◼ Hardware ◼ Link ◼ Access ◼ Network ◼ Application Delay Constraints Rate Constraints Energy Constraints 11
- 12. Limitations and difficulties ◼ Wireless is convenient and less expensive. ◼ Limitations and political and technical difficulties inhibit wireless technologies. ◼ Lack of an industry-wide standard. ◼ Device limitations ◼ E.g., small LCD on a mobile telephone can only displaying a few lines of text. 12
- 13. Current Wireless Systems ◼ Cellular Systems ◼ Wireless LANs ▪ 802 type wireless networks ▪ WiFi 802.11 ▪ WiMax 802.16 ▪ Bluetooth ▪ Zigbees ◼ Satellite Systems ◼ Paging Systems ◼ Cordless Telephone Systems 13
- 14. Satellite Links SW Radio MW Radio FM Radio Mobile Telephony, WLL WLANs Blueooth IR Wireless Systems: Range Comparison 1,000 Km 100 Km 10 Km 100 m 10 m 1 m
- 15. EM Spectrum Propagation characteristics are different in each frequency band UV 1 MHz 1 kHz 1 GHz 1 THz 1 PHz 1 EHz infrared visible X rays Gamma rays LF HF VHF UHF SHF EHF MF 902 – 928 Mhz 2.4 – 2.4835 Ghz 5.725 – 5.785 Ghz ISM band 30kHz 300kHz 3MHz 30MHz 300MHz 30GHz 300GHz 10km 1km 100m 10m 1m 10cm 1cm 100mm 3GHz
- 16. Historical background Early Advances in Wireless Communications 1800 1900 1850 1935 1793
- 17. Evolution to cellular networks communication anytime, anywhere ◼ Radio communication was invented by Nokola Tesla and Guglielmo Marconi • In 1893, Nikola Tesla made the first public demonstration of wireless (radio) telegraphy. • Guglielmo Marconi conducted long distance (over see) telegraphy 1897. ◼ In 1940 the first walkie-talkie was used by the US military. ◼ In 1947, John Bardeen and Walter Brattain from AT&T’s Bell Labs invented the transistor (semiconductor device used to amplify and switch electronic signals). ◼ AT&T introduced commercial radio communication: car phone – two way radio link to the local phone network. ◼ In 1979 the first commercial cellular phone service was launched by the Nordic Mobile Telephone (in Finland, Sweden, Norway, Denmark). 17
- 18. Generations of Terrestrial Commercial Wireless Systems ▪ First Generation (1G): Analog, voice only, mostly vehicular communications, FM. ▪ Second Generation (2G): Narrowband TDMA and CDMA, voice and low data rate, portable units. - 2.5G : increased data transmission capabilities ▪ Third Generation (3G): Wideband TDMA and CDMA, voice and high data rate, portable units. 18
- 19. Cellular networks: From 1G to 3G ◼ 1G: First generation wireless cellular: Early 1980s ◼ Analog transmission, primarily speech: AMPS (Advanced Mobile Phone Systems) and others ◼ 2G: Second generation wireless cellular: Late 1980s ◼ Digital transmission ◼ Primarily speech and low bit-rate data (9.6 Kbps) ◼ High-tier: GSM, IS-95 (CDMA), etc ◼ 2.5G: 2G evolved to medium rate (< 100kbps) data ◼ 3G: future Broadband multimedia ◼ 144 kbps - 384 kbps for high-mobility, high coverage ◼ 2 Mbps for low-mobility and low coverage ◼ Beyond 3G: research in 4G
- 20. 1G - Analog Technology 20 AMPS : Advanced Mobile Phone System in U.S. TACS: Total Access Cellular System NMT 450: Nordic Mobile Telephone System in Europe. NIT: Nippon Telephone and Telegraph Company in Japan.
- 21. 2G - Digital Technology ▪ GSM (Global System Mobile) - TDMA/FDD - 8 users for each 200kHz channel ▪ IS-95 (cdmaOne) - CDMA/FDD - 64 users for each 1.25 MHz channel ▪ US Digital AMPS (IS-136) - TDMA/FDD - 3 users for each 30kHz channel - also known as NADC ▪ PDC (Personal Digital Cellular) - TDMA/FDD - 3 users for each 25kHz channel 21
- 22. 2G - Digital Technology 22 GSM :Global System Mobile. IS95: interim Standard(IS-95). PDC: Personal Digital Cellular.
- 23. 2.5G Mobile Radio Networks ▪ The 2G digital standards (GSM/CDMAone or IS-95/PDC) - Narrowband and designed mainly for voice services using circuit switched data modems. - Support single user data rates = 9.6 k bits/s. - Only support limited Internet browsing and SMS. ▪ The data-centric 2.5G technologies retrofit the 2G standards for compatibility with increased throughput data rates required to support modern Internet applications. ▪ The appropriate 2.5G upgrade path for a particular wireless carrier must match the original 2G technology choice made earlier by the same carrier. 23
- 24. 2.5G Mobile Radio Networks 24 ▪ HSCSD (High Speed Circuit Switched Data) • bundling of channels for higher rate • 57.6 kbits/sec • Disadvantage: Channels blocked unnecessary ▪ GPRS (General Packet Radio Services) (mid 1990s) • Packet switching • Using free slots only • Upto 171.2 kbits/sec ▪ EDGE (Enhanced Data rate for GSM Evolution) • Adaptive modulation (8PSK instead of GMSK) • Up to 384 kbits/sec
- 25. Migration to 3G ▪ ITU had formulated a plan to establish a single, ubiquitous wireless communications standard throughout the world (IMT-2000). ▪ The migration from current 2G systems to 3G ---- GSM/IS136/PDC ⇛ WCDMA (UMTS) WCDMA is based on the network fundamentals of GSM, as well as the merged versions of GSM and IS-136 through EDGE. ---- CDMA (IS-95 based) ⇛ cdma2000 ---- TD-SCDMA ITU: International Telecommunication Union WCDMA: Wideband CDMA UMTS: Universal Mobile Télécommunications Service TD-SCDMA: Time Division-Synchronous CDMA 25
- 27. 3G Mobile Radio Networks 27 ▪ UMTS (Universal Mobile Telecommunication System) • Idea was to develop universal system • Different target rates for different mobility scenarios • Common air-interface W-CDMA ▪ HSPA (High Speed Packet Access) (~2006) • Enhancement over WCDMA: higher order modulation, rate control, etc. • Upto 14 Mbits/sec • Backward compatible Beyond 3G ▪ LTE (Long-Term Evolution) • Telecom system for 2020 • Backward compatibility is not required • Higher data rates and lower delays are required at cell edges • IP based networks • OFDMA, MIMO
- 28. 4G/LTE Cellular ◼ Much higher data rates than 3G (50-100 Mbps) ◼ 3G systems has 384 Kbps peak rates ◼ Greater spectral efficiency (bits/s/Hz) ◼ More bandwidth, adaptive OFDM-MIMO, reduced interference ◼ Flexible use of up to 100 MHz of spectrum ◼ 10-20 MHz spectrum allocation common ◼ Low packet latency (<5ms). ◼ Reduced cost-per-bit (not clear to
- 29. 5G Upgrades from 4G
- 31. Future Wireless Networks Communication Among People and Devices Next-Gen Cellular/WiFi Smart Homes/Spaces Autonomous Cars Smart Cities Body-Area Networks Internet of Things All this and more …
- 32. Wireless Local Area Network (WLANs) WiFi - IEEE 802.11 ◼ Infrastructure mode ▪ Wireless home/office networks • Low cost, robust • Lower data rate, limited capacity ◼ 900 MHz, 2.4 GHz, 5.8 GHz ◼ Mobility management – Mobile IP ◼ Ad hoc mode ▪ Static networks • Mesh – low cost infrastructure ◼ Mobile (MANET) • Emergencies and disaster relief • Military applications 32
- 33. Comparison: infrastructure vs. ad-hoc networks Infrastructure network ad-hoc network 33
- 34. IEEE 802.11 Wireless LAN standard 34 in 1997 the FCC allocated 300 MHz of unlicensed spectrum in the Industrial Scientific and Medical (ISM) bands of 5.150-5.350 GHz and 5.725-5.825 GHz for the express purpose of supporting low-power license-free spread spectrum data communication. This allocation is called the Unlicensed National Information Infrastructure (UNII) band.
- 35. IEEE 802.11 Protocols 35 Source: Wikipedia.org
- 36. Wireless Mesh Networks ◼ Challenges • Efficient routing • Efficient medium access • Security • Limited capacity 36
- 37. Mobile Ad hoc Networks - MANET ◼ Self configurable and self healing ◼ Major Constraints – Highly dynamic topology – Limited radio capacity – Limited power (battery operated devices) ◼ Challenges – Routing – Resource management – Security 37
- 38. DSRC – Dedicated Short Range Communications ◼ ITS (Intelligent Transport Systems) applications – Vehicle-to-vehicle – Vehicle-to-infrastructure ◼ IEEE 802.11 p, 5.9 GHz (US), 5.8 GHz (Japan, EU) ◼ Physical layer issues – Mobility – Dynamic multipath 38 Picture source: http://www.ercim.org
- 39. Bluetooth ◼ Universal radio interface for wireless personal area networks ◼ Interconnecting computers, peripherals, handheld devices, etc. ◼ Replacement of IrDA (infrared) ◼ Short range (10 m), low power consumption, license- free 2.45 GHz ISM ◼ Voice and data transmission, approx. 1 Mbit/s gross data rate 39 Picture source: www.home.agilent.com
- 40. Example of a Personal Area Network (PAN) as provided by the Bluetooth standard. 40
- 41. Wireless Sensor Networks ◼ Cooperatively monitor physical or environmental conditions, e.g., temperature, sound, vibration, etc. ◼ No official standards yet – Zigbee based on the IEEE 802.15.4 WPANs ◼ Limited battery life and memory ◼ Data management for efficient communication ◼ Self-configuration and localization 41
- 42. WMANs - WiMAX– IEEE 802.16 ◼ Worldwide Interoperability for Microwave Access (WiMax) 802.16 – Longer range (upto 30 miles) – Up to 40 Mbps for 3-10 km range – 3.5 GHz, 2.3/2.5 GHz, or 5 GHz – Last mile wireless broadband access ◼ Mobile WiMax – Mobility of cellular networks at braodband speeds 42 Picture source: www.tech2.com
- 43. Paging Systems ◼ Paging systems are communication systems that send brief messages to a subscriber. ◼ paging systems may cover a limited range of 2 to 5 km. ◼ The paging control center dispatches pages received from the PSTN throughout several cities at the same time. 43
- 44. Cordless Telephone Systems ◼ Cordless telephone systems are full duplex communication systems that use radio to connect a portable handset to a dedicated base station, which is then connected to a dedicated telephone line with a specific telephone number on the public switched telephone network (PSTN). ◼ Base stations provide coverage ranges up to a few hundred meters. 44
- 45. Wireless Local Loops (WLL) ◼ Last mile wireless access for telephone and internet ◼ Useful for rural and isolated areas and emergency situations ◼ Fast deployment: 2- 6 months vs. 3- 5 years for wireline network ◼ Low construction, operational, and extension costs ◼ Technology alternatives – Modified cellular systems – Satellite-based systems – WiMax 45
- 46. Any Question