1 / 27

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:

september-witt
Download Presentation

NETW 701:Wireless Communications

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related