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NETW 701:Wireless Communications

NETW 701:Wireless Communications. Course Instructor : Tallal Elshabrawy Instructor Office : C3.321 Instructor Email : tallal.el-shabrawy@guc.edu.eg Teaching Assistants : Eng. Phoebe Edward Emails : phoebe.edward2@guc.edu.eg,. Text Book and References. Text Book:

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NETW 701:Wireless Communications

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  1. NETW 701:Wireless Communications Course Instructor : Tallal Elshabrawy Instructor Office : C3.321 Instructor Email : tallal.el-shabrawy@guc.edu.eg Teaching Assistants : Eng. Phoebe Edward Emails : phoebe.edward2@guc.edu.eg,

  2. Text Book and References Text Book: • “Wireless Communications: Principles and Practice 2nd Edition”, T. S. Rappaport, Prentice Hall, 2001 Reference Books: • “Modern Wireless Communications”, S. Haykin and, M. Moher, Prentice Hall, 2004 • “Mobile Wireless Communications”, M. Schwartz Cambridge University Press, 2005

  3. Course Pre-Requisites • Review communication theory COMM 502

  4. 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 wireless communication networks • Provide an insight to different practical wireless communication networks

  5. Course Contents Overview

  6. Wireless Communication Channels Signal Interference Power PT Frequency d (Km)

  7. Wireless Communication Channels Signal Interference Large-Scale Parameters • Distance Pathloss Power PT PT+PL(d) Frequency d (Km)

  8. Wireless Communication Channels Signal Interference Large-Scale Parameters • Distance Pathloss • Lognormal Shadowing Power PT PT+PL(d) Frequency d (Km)

  9. Wireless Communication Channels Signal Interference Large-Scale Parameters • Distance Pathloss • Lognormal Shadowing Power PT PT+PL(d) Frequency d (Km)

  10. Wireless Communication Channels Signal Interference Large-Scale Parameters • Distance Pathloss • Lognormal Shadowing Power PT PT+PL(d) Frequency d (Km)

  11. Wireless Communication Channels Signal Interference Large-Scale Parameters • Distance Pathloss • Lognormal Shadowing Power PT PT+PL(d) PT+PL(d)+X Frequency d (Km)

  12. Wireless Communication Channels Signal Interference Large-Scale Parameters • Distance Pathloss • Lognormal Shadowing Small-Scale Parameters • Multi-Path Fading Power PT PT+PL(d) PT+PL(d)+X Frequency d (Km)

  13. Wireless Communication Channels Distance Pathloss Mobile Speed 3 Km/hr PL=137.744+ 35.225log10(DKM) d Lognormal Shadowing Mobile Speed 3 Km/hr ARMA Correlated Shadow Model d Small-Scale Fading Mobile Speed 3 Km/hr Jakes’s Rayleigh Fading Model d

  14. Wireless Medium Access Techniques • FDMA (Frequency Division Multiple Access) • Channel bandwidth divided into frequency bands • At any given instant each band should be used by only one user • TDMA (Time Division Multiple Access) • System resources are divided into time slots • Each user uses the entire bandwidth but not all the time • CDMA (Code Division Multiple Access) • Each user is allocated a unique code to use for communication • Users may transmit simultaneously over the same frequency band • SDMA (Space Division Multiple Access) • System resources are reused with the help of spatial separation

  15. Signal Reception and SINR Factors influencing SINR: • Number of Interferers • Identity of Interferers • Interference Power • Interference Channels Signal Interference Reliable Signal Reception requires adequate SINR (Signal to Interference and Noise Ratio) S I

  16. Signal Reception and SINR Factors influencing SINR: • Number of Interferers • Identity of Interferers • Interference Power • Interference Channels Signal Interference Reliable Signal Reception requires adequate SINR (Signal to Interference and Noise Ratio) S I

  17. Signal Reception and SINR Factors influencing SINR: • Number of Interferers • Identity of Interferers • Interference Power • Interference Channels Signal Interference Reliable Signal Reception requires adequate SINR (Signal to Interference and Noise Ratio) I

  18. System Capacity • Maximum number of customers that may be satisfactorily supported within the wireless network • Example Criteria for a Satisfied-User: • Number of Interfering sessions < N • Outage Probability <ψTH

  19. Advances in Wireless Comm.: Multi-Carrier Modulation • Subdivide wideband bandwidth into multiple Orthogonal narrowband sub-carriers • Each sub-carrier approximately displays Flat Fading characteristics • Flexibility in Power Allocation & Sub-carrier Allocation to increase system capacity

  20. Advances in Wireless Comm.: MIMO • Frequency and time processing are at limits • Space processing is interesting because it does not increase bandwidth • MIMO technology is evolving in different wireless technologies • Cellular Systems • WLAN

  21. Wireless Communications Channels: Large-Scale Pathloss

  22. Isotropic Radiation • An Isotropic Antenna: • An antenna that transmits equally in all directions • An isotropic antenna does not exist in reality • An isotropic antenna acts as a reference to which other antennas are compared Power Flux Density d From “Wireless Communications” Edfors, Molisch, Tufvesson

  23. Power Reception by an Isotropic Antenna Power Received by Antenna Ae=ARx Effective Area of Antenna Power Received by Isotropic Antenna From “Wireless Communications” Edfors, Molisch, Tufvesson LP Free-space Path-loss between two isotropic antennas

  24. Directional Radiation • A Directional Antenna: • Transmit gain Gt is a measure of how well an antenna emits radiated energy in a certain direction relative to an isotropic antenna. • Receive gain Gr is a measure of how well the antenna collects radiated energy in a given area relative to an isotropic antenna. Maximum (Peak) Antenna Gain Main Lobe Maximum transmit or receive antenna Gain 3 dB Beam Width Side Lobes Antenna Pattern for Parabolic (dish-shaped) antenna

  25. The Friis Equation Friis Equation • The received power falls off as the square of the T-R separation distance • The received power decays with distance at a rate of 20 dB/decade • Valid for Line of Sight (LOS) satellite communications • The Friis free-space model is only valid for values of d in the far field. The far field is defined as the region beyond the far field distance df D is the largest linear dimension of the transmitting antenna aperture Note: df must also satisfy df>>D, df>>λ

  26. PR(d) in the Far Field • The Friis equation is not valid at d=0 • PR(d) could be related to a power level PR(d0) that is measured at a close in distance d0 that is greater than df

  27. Relating Power to Electric Field Alternative formula for power flux density Power Flux Density where E depicts the electric field strength and η is the intrinsic impedance of free-space Power Received by Antenna

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