We think you have liked this presentation. If you wish to download it, please recommend it to your friends in any social system. Share buttons are a little bit lower. Thank you!
Presentation is loading. Please wait.
Published byHannah Hernandez
Modified over 3 years ago
© 2008 Cisco Systems, Inc. All rights reserved.WLAN-RF-Principles-1 Wireless LAN RF Principles
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Wireless Spectrum Wireless networks use RF signals RF are electromagnetic waves Spectrum defines waves sizes, grouped by categories Wireless network radio range is in the microwave segment
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Frequency The frequency determines how often a signal is seen 1 cycle per second is 1 Hertz Low frequency travel farther in the air than higher frequencies
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v The signal generated in the transmitter is sent to the antenna The electrons movement generate an electric field which is a wave The size of the cycle pattern is called the wavelength Wavelength
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Amplitude is the vertical distance, or height, between crests For the same wavelength and frequency, different amplitude can exist It represents the quantity of energy injected in the signal This value is usually regulated as it can affect the receivers Amplitude
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Free Path Loss As the wave spreads away from the emitter, it gets weaker: –The quantity of energy declines as the distance increases: the available quantity of energy available on each point of the circle is less as the circle is larger; the receiver catches only part of this energy Determining a range is determining the energy loss depending on the distance
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Absorption Absorption takes energy from the wave This energy is dissipated in heat in the obstacle When 100% of the energy is taken, the wave stops The effect of absorption is to reduce amplitude The signal is therefore less powerful, but keeps the same wavelength and frequency
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Reflection Part of the energy is reflected Part may be transmitted The angle of reflection is the same as the initial angle Reflection depends on the material roughness relative to the wavelength and the angle Amplitude has no impact
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Multipath Occurs when the signal reflects on surfaces and arrives to the receiver at different times Delayed multiple copies of the same signal hit the receiver Depends on the wavelength and the position of the receiver
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Multipath: Phase 2 signals are in phase when their cycles crests coincide Being out of phase weakens both signal or cancel them if amplitude and wavelength are the same
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Occurs when micro particles deviate the wave in multiple directions Affects shorter wavelengths more than longer ones Can weaken the signal or block it Scattering
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Refraction Occurs when the wave passes from one medium to another: direction change Minor effects on indoor networks Can have high impacts on outdoor long range links
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Necessary for good signal transmission Earth curvature plays a role in outdoor links from a few miles (depends on transmitter and receiver elevation Visual obstacles may or may not prevent radio line of sight Line of Sight
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Fresnel Zone Determines an area around radio line of sight where reflections have most negative impact on the signal Should be at least 60% free from obstacles
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v RSSI and SNR RSSI is the signal strength indicator dBm value transformed from a a vendor dependent grading coefficient Usually negative value, the closer to 0 the better SNR is signal strength relative to noise level The higher the better
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Summary The wireless spectrum expresses the range of radio waves Frequency is how often the same cycle repeats per second Wavelength is the distance of the same points in a signal cycle Amplitude is how strong the signal is, and how high the wave Once radiated, some energy will be lost as the signal spreads, incurring Free Path Loss As the signal goes through obstacles, absorption weakens it It can also bounce on objects, which is reflection
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v Summary (cont.) When reflection occurs and several signals arrive at the receiver, a multipath issue occurs Scattering occurs when the signal is reflected in many directions by small obstacles Refraction occurs when the signal goes from one medium to another and changes direction For a signal to be transmitted in good conditions, radio line of sight should exist between endpoints Around the line of sight, a zone, the first Fresnel zone, should be mostly free from obstacles RSSI will determine received signal strength and SNR the signal- to-noise ratio at the receiver
© 2008 Cisco Systems, Inc. All rights reserved.IUWNE v
Certified Wireless Network Administrator (CWNA) PW0-105 Chapter 2 Radio Frequency Fundamentals.
Chapter 2 Radio Frequency Fundamentals. Exam Essentials Understand wavelength, frequency, amplitude, and phase. –Know the definition of each RF characteristic.
Characteristics Radio Frequency signals consist of the following: Polarity Wavelength Frequency Amplitude Phase These characteristics are defined by the.
Wireless Transmission Fundamentals (Physical Layer) Professor Honggang Wang
RF Fundamentals Lecture 3. 2 Objectives Describe RF loss and gain, and how it can be measured List some of the characteristics of RF antenna transmissions.
Wave Properties. S8P4. Students will explore the wave nature of sound and electromagnetic radiation. d. Describe how the behavior of waves is affected.
Chapter 02 Radio Frequency & Antenna Fundamentals Center for Information Technology.
Electromagnetic Wave Theory Lecture 7. Electromagnetic Radiation Fundamentals of electromagnetic waves Effects of environment Propagation of waves Surface.
Radio Frequency Fundamentals Wireless Networking Unit.
F ACULTY OF C OMPUTER S CIENCE & E NGINEERING Chapter 02. Radio Frequency.
CWNA Guide to Wireless LANs, Third Edition Chapter 3: Radio Frequency Fundamentals.
The Nature of Waves What is a wave? A wave is a repeating disturbance or movement that transfers energy through matter or space Waves transfer energy.
Wi-fi Range. Topics Discussed When we say range or coverage, what do we mean? What factors can affect range? Why are there so many different designs of.
Wave Information. 1.A wave is an oscillation or back and forth OR up and down movement. 2. Waves that travel through matter are called mechanical waves.
Waves. The Nature of Waves What is a mechanical wave? A wave is a repeating disturbance or movement that transfers energy through matter or space
TRANSMISSION MEDIA T.Najah Al-Subaie Kingdom of Saudi Arabia Prince Norah bint Abdul Rahman University College of Computer Since and Information System.
Radio Frequency and Antenna Fundamental. Fundamentals of Electromagnetic Waves.
Radiant Energy Electromagnetic wave, crest, trough, medium, amplitude, wavelength, frequency, Electromagnetic Spectrum, Visible Spectrum reflection, absorption.
General Frequency Ranges Microwave frequency range –1 GHz to 40 GHz –Directional beams possible –Suitable for point-to-point transmission –Used for satellite.
WAVES Essential Questions: What is a wave? How do waves travel? What are the types of waves? What are the properties of waves? What are 4 types.
ELECTRONIC COMMUNICATIONS A SYSTEMS APPROACH CHAPTER Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Electronic Communications: A Systems.
WIRELESS COMMUNICATIONS Assist.Prof.Dr. Nuray At.
CSE5807 Wireless and Personal Area Networks Lecture 2 Radio Communications Principles Chapters 2,5 and 11 Stallings.
© 2003, Cisco Systems, Inc. All rights reserved. FWL 1.0—3-1 Wireless Radio Technology Olga Torstensson Halmstad University.
WAVES Wave motion allows a transfer of energy without a transfer of matter.
CELLULAR COMMUNICATIONS 2. Radio Wave Propagation.
Chapter Fifteen: Radio-Wave Propagation. Introduction Radio waves are one form of electromagnetic radiation Electromagnetic radiation has a dual nature:
W.lilakiatsakun. Radio Wave Fundamental Radio Wave Attributes RF System Component RF Signal Propagation RF Mathematics.
Electromagnetic Radiation Most remotely sensed data is derived from Electromagnetic Radiation (EMR). This includes: Visible light Infrared light (heat)
P6 – The Wave Model of Radiation. Waves A wave consists of disturbances that transfer energy in the direction that the wave travels, without transferring.
Antennas and Propagation Chapter 5. Introduction An antenna is an electrical conductor or system of conductors Transmission - radiates electromagnetic.
Propagation characteristics of wireless channels Lecture 2.
Electromagnetic Energy. Energy is the ability to do work. Electromagnetic energy is the energy radiated by all matter in the universe that is not at absolute.
Dylan Zywicki th hour. What is a wave? * A wave is any disturbance that transmits energy through matter or empty space. * Some examples are;
© 2003, Cisco Systems, Inc. All rights reserved. FWL 1.0— © 2003, Cisco Systems, Inc. All rights reserved.
IE 419/519 Wireless Networks Lecture Notes #5 Antennas and Propagation.
1 Chapter 5. Antennas and Propagations Wen-Shyang Hwang KUAS EE.
Wireless Networking Radio Frequency and Antenna Fundamentals Module-02 Jerry Bernardini Community College of Rhode Island 6/15/2015Wireless Networking.
ElectroMagnetic Radiation Spectrum The basics about light and waves.
Transverse Waves and Lights. Essential Question: What is a wave?(pg. 43) Disturbance in matter than transfers energy from one place to another.
3.1 Chapter 3 Data and Signals Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
CWNA Guide to Wireless LANs, Second Edition Chapter Three How Wireless Works.
Characteristics of Waves Chapter 9 S8P4a. Identify the characteristics of electromagnetic and mechanical waves. S8P4d. Describe how the behavior of waves.
Waves, Light, and Sound Vocabulary. WAVES Mechanical Waves: energy that travels through matter; examples include sound, ocean waves, and earthquake waves.
Air Interface. 2 Analog Transmission n In analog transmission, the state of line can vary continuously and smoothly among an infinite number of states.
Propagation Measurements and Models for Wireless Communications Channels Brian Alexander.
Waves. A wave is an oscillation that travels from one place to another. The word oscillation means a motion that repeats regularly. The surface of the.
Light and the Electromagnetic Spectrum. Light Phenomenon Isaac Newton ( ) believed light consisted of particles By 1900 most scientists believed.
Characteristics of Waves. 1What is a wave? A wave is a traveling disturbance that carries energy from one place to another. 2.Where do waves get their.
© 2017 SlidePlayer.com Inc. All rights reserved.