Spread Spectrum Spread-spectrum techniques are methods by which energy generated in a particular bandwidth is deliberately spread in the frequency domain,

Slides:



Advertisements
Similar presentations
EE578 Assignment #5 Abdul-Aziz.M Al-Yami November 8 th 2010.
Advertisements

IE 419/519 Wireless Networks Lecture Notes #6 Spread Spectrum.
Spread Spectrum Chapter 7.
Spread Spectrum Chapter 7. Spread Spectrum Input is fed into a channel encoder Produces analog signal with narrow bandwidth Signal is further modulated.
Lecture 7: Spread Spectrum
April 25, 2005ECE 457 Cellular Communication ECE 457 Spring 2005.
Lecture 8: Spread Spectrum
Chapter 7 Multiple Division and Signal Encoding Techniques
Spread Spectrum Input is fed into a channel encoder
Spread Spectrum Steganography Nick Sterling Sarah Wahl Sarah Summers.
William Stallings Data and Computer Communications 7th Edition
Data and Computer Communications Eighth Edition by William Stallings Chapter 9 – Spread Spectrum.
SPREAD SPECTRUM In spread spectrum (SS), we combine signals from different sources to fit into a larger bandwidth, but our goals are to prevent eavesdropping.
3. Encoding Techniques and Spread Spectrum
Spread Spectrum Steganography
1 CMPT 371 Data Communications and Networking Spread Spectrum.
Wireless & Mobile Networking: Multiple Division Techniques
Direct Sequence Spread- Spectrum with Frequency Hopping.
Wireless Networks Spring 2005 Spread Spectrum. Wireless Networks Spring 2005 Spread Spectrum  Input is fed into a channel encoder oProduces analog signal.
Spread Spectrum Techniques
TYPES OF SS TECHNIQUES THE FUTURE LIES WITHIN. INTRODUCTION There are four basic types classified according to the point of insertion of PN code –D–Direct.
DCSP-4: Modem Jianfeng Feng Department of Computer Science Warwick Univ., UK
Spread Spectrum Lecture 21.
1 Introduction to. 2 Contents: DEFINITION OF SPREAD SPECTRUM ( SS ) CHARACTERISTICS OF SPREAD SPECTRUM BASIC PRINCIPLES OF DIRECT SEQUENCE SPREAD SPECTRUM.
Lecture 8: Spread Spectrum
Modulation-Why? 1. Low frequency signal has less energy, which means it can travel less distance. 2. Practibility of antenna.
Data and Computer Communications Eighth Edition by William Stallings Lecture slides by Lawrie Brown Chapter 9 – Spread Spectrum.
Signal Encoding, Spread Spectrum. Basic Encoding Techniques Digital data to analog signal Amplitude-shift keying (ASK) Amplitude difference of carrier.
Lecture02 Spread Spectrum Communication By Engr. Muhammad Ashraf Bhutta.
From Stallings, modified and added1 Spread Spectrum Session 5 Nilesh Jha.
Spread-Spectrum Techniques
1 Chapter 7. Spread Spectrum Wen-Shyang Hwang KUAS EE.
CDMA TECHNOLOGY DEFINITION OF CDMA TECHNOLOGY A coding scheme, used as a modulation technique, in which multiple channels are independently coded for.
Spread Spectrum Chapter 7. Spread Spectrum Form of communication Can be used to transmit analog or digital data using an ANALOG signal Idea: spread the.
Lecture 4 Spread Spectrum.
1 William Stallings Data and Computer Communications 7 th Edition Chapter 9 Spread Spectrum.
Stallings, Wireless Communications & Networks, Second Edition, © 2005 Pearson Education, Inc. All rights reserved Multiple Access Techniques.
Code Division Multiple Access (CDMA) Transmission Technology
Data and Computer Communications Eighth Edition by William Stallings Lecture slides by Lawrie Brown Chapter 9 – Spread Spectrum.
Data and Computer Communications Ninth Edition by William Stallings Chapter 9 – Spread Spectrum Data and Computer Communications, Ninth Edition by William.
1 Spread Spectrum Technology. 2 What is Spread Spectrum(SS) Spread Spectrum (SS) technology was first introduced by military as a way of sending secure.
Code Division Multiple Access (CDMA) Transmission Technology
Stallings, Wireless Communications & Networks, Second Edition, © 2005 Pearson Education, Inc. All rights reserved Spread Spectrum Chapter.
TUNALIData Communication1 Spread Spectrum Chapter 9.
Wireless LAN Technology Chapter 13. Wireless LAN  Wireless LAN is one that make use of a wireless transmission medium.  Wireless LAN use infrared or.
DATA AND COMPUTER COMMUNICATIONS Eighth Edition by William Stallings Lecture slides by Lawrie Brown Chapter 9 – Spread Spectrum.
William Stallings Data and Computer Communications 7th Edition
CSE 5345 – Fundamentals of Wireless Networks
Lecture 7 CSMA and Spread Spectrum Dr. Ghalib A. Shah
Chapter 5: Third generation systems-Wideband Digital Modulation
Mobile Communications
Outline Introduction Type of Multiplexing FDMA TDMA CDMA Future Work
DIRECT SEQUENCE SPREAD SPECTRUM WITH FREQUENCY HOPPING
TLEN 5830 Wireless Systems Lecture Slides 28-Sep-2017
Data and Computer Communications Eighth Edition by William Stallings Lecture slides by Lawrie Brown Chapter 9 – Spread Spectrum.
Spread Spectrum Chapter 7.
Spread Spectrum L.Tahani Aljehani.
Spread Spectrum Multiplexing combines signals from several sources to achieve bandwidth efficiency: The available bandwidth of a link is divided between.
Chapter 5: Third generation systems-Wideband Digital Modulation
Spread Spectrum A signal that occupies a bandwidth of B, is spread out to occupy a bandwidth of Bss All signals are spread to occupy the same bandwidth.
Wireless Mesh Networks
CSE 4215/5431: Mobile Communications Winter 2010
CSE 4215/5431: Mobile Communications Winter 2011
Wireless Networks Fall 2007
3. Encoding Techniques and Spread Spectrum
Spread Spectrum Chapter 7.
William Stallings Data and Computer Communications 7th Edition
Multiplexing Simultaneous transmission of multiple signals across a single data link As data & telecomm use increases, so does traffic Add individual links.
William Stallings Data and Computer Communications 7th Edition
Spread Spectrum Analog or digital data Analog signal
Presentation transcript:

Spread Spectrum Spread-spectrum techniques are methods by which energy generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of secure communications, increasing resistance to natural interference and jamming, and to prevent detection.

Spread Spectrum Input is fed into a channel encoder Produces analog signal with narrow bandwidth Signal is further modulated using sequence of digits Spreading code or spreading sequence Generated by pseudonoise, or pseudo-random number generator Effect of modulation is to increase bandwidth of signal to be transmitted

Spread Spectrum On receiving end, digit sequence is used to demodulate the spread spectrum signal Signal is fed into a channel decoder to recover data

Spread Spectrum

What can be gained from apparent waste of spectrum? Immunity from various kinds of noise and multipath distortion Can be used for hiding and encrypting signals Several users can independently use the same higher bandwidth with very little interference

Frequency Hoping Spread Spectrum (FHSS) Signal is broadcast over seemingly random series of radio frequencies A number of channels allocated for the FH signal Width of each channel corresponds to bandwidth of input signal Signal hops from frequency to frequency at fixed intervals Transmitter operates in one channel at a time Bits are transmitted using some encoding scheme At each successive interval, a new carrier frequency is selected

Frequency Hoping Spread Spectrum Channel sequence dictated by spreading code Receiver, hopping between frequencies in synchronization with transmitter, picks up message Advantages Eavesdroppers hear only unintelligible blips Attempts to jam signal on one frequency succeed only at knocking out a few bits

Frequency Hoping Spread Spectrum

FHSS Using MFSK MFSK signal is translated to a new frequency every T c seconds by modulating the MFSK signal with the FHSS carrier signal For data rate of R: duration of a bit: T = 1/R seconds duration of signal element: T s = LT seconds T c  T s - slow-frequency-hop spread spectrum T c < T s - fast-frequency-hop spread spectrum

FHSS Performance Considerations Large number of frequencies used Results in a system that is quite resistant to jamming Jammer must jam all frequencies With fixed power, this reduces the jamming power in any one frequency band