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 byBeatrice Branyan
Modified over 2 years ago
The University of Iowa. Copyright© 2005 A. Kruger 1 Introduction to Wireless Sensor Networks Spread Spectrum and CDMA 24 February 2005
The University of Iowa. Copyright© 2005 A. Kruger 2 Organizational Monday 4:30-5:20Room 4511 SC Thursday12:30-1:20Room 3220 SC Please note that the room numbers are different for Mondays and Thursdays. Class Website www.engineering.uiowa.edu/~ece195/2005/ Class Time Midterm Exam Time: March 10, 2005
The University of Iowa. Copyright© 2005 A. Kruger 3 Modulation Schemes Basic Question –Why do we modulate at all? AM – amplitude modulation FM frequency modulation OOK – On/Of Keying PAM, M-PAM… FSK, PSK, QPSK, OQPSK, M-PSK, MSK, GMSK
The University of Iowa. Copyright© 2005 A. Kruger 4 FSK
The University of Iowa. Copyright© 2005 A. Kruger 5 OOK –On/Off Keying 1110 0 Relationship with TDMA?
The University of Iowa. Copyright© 2005 A. Kruger 6 Spread Spectrum Transmitted signal has much greater (20-200 times) the bandwidth that base band signal External function determines bandwidth Frequency Power Direct Sequence Frequency Hopping
The University of Iowa. Copyright© 2005 A. Kruger 7 Frequency Hop Systems Bluetooth (PAN) –1,600 hops /second –79 randomly selected hop frequencies –2.402 to 2.480 GHz –Dwell time 625 microsecond –During dwell time data are transmitted at 1 Mbps
The University of Iowa. Copyright© 2005 A. Kruger 8 Spread Spectrum Noise Performance
The University of Iowa. Copyright© 2005 A. Kruger 9 Spread Spectrum Pros & Cons Pros –Better noise/interference performance –Better multipath performance –Better channel utilization (why) –Security Cons –More complex implementation
The University of Iowa. Copyright© 2005 A. Kruger 10 CDMA Steps –Apply orthogonal spreading codes to spread baseband signals –Transmit (wide spectrum) –Receive –Correlate to despread Unwanted codes/signals are discarded –Narrowband filter Spreading codes are carefully designed Spreading code rate is chip rate
The University of Iowa. Copyright© 2005 A. Kruger 11 CDMA (Direct Sequence) Orthogonal codes: C1 = (1,1) and C2 = (1,-1) C1.C1 = (1,1).(1,1) = +1 C1.-C1 = (1,1).(-1,-1) = -1 C1.C2 = (1,1).(1,-1) = 0 C1.-C2 = (1,1).(-1,1) = 0
The University of Iowa. Copyright© 2005 A. Kruger 12 CDMA C1 = (1,1) and C2 = (1,-1) Transceiver 1 uses code C1 –To send 1 use C1 –To send 0 use –C1 –=> for 10 send 1 1 0 0 Transceiver 2 uses code C2 –To send 1 use C2 –To send 0 use –C2 –=> for 11 send 1 -1 1 - 1 Signals add up in air: 2 0 1 -1 Receiver 1 decodes by taking dot product with C1 (2, 0).(1, 1) (1, -1).(1, 1) = 10 Receiver 2 decodes by taking dot product with C2 (2,0).(1,-1) (1, -1).(1,-1) = 1 1
The University of Iowa. Copyright© 2005 A. Kruger 13
The University of Iowa. Copyright© 2005 A. Kruger 14 FDMA vs TDMA vs CDMA
The University of Iowa. Copyright© 2005 A. Kruger 15 Review Questions Explain in a paragraph what frequency-hopping spread spectrum is. What is an orthogonal code? Give an example of an orthogonal code. Explain why spread spectrum techniques can provide better channel utilization than conventional (e.g., AM, FM). List an briefly explain four advantages of spread spectrum. What is a disadvantage of spread spectrum modulation? True or false – CDMA can be seen as an example of what is known a direct sequence spread spectrum? What is FSK and OOK? Use simple figures to explain.
The University of Iowa. Copyright© 2005 A. Kruger 16 Review Question Show that the following codes are orthogonal The output from a CDMA receiver is “1 2 2 1 1” which contains messages from two transmitters. The spreading codes are: Decode the two messages. C1 = 1 1 1 1 C2 = 1 -1 1 -1 C3 = 1 1 -1 -1 C4 = 1 -1 -1 1 C1 = 1 1 C2 = 1 -1
Code Division Multiple Access (CDMA) Transmission Technology
Stallings, Wireless Communications & Networks, Second Edition, © 2005 Pearson Education, Inc. All rights reserved Multiple Access Techniques.
Digital Modulation Schemes
Copyright © 2003, Dr. Dharma P. Agrawal and Dr. Qing-An Zeng. All rights reserved. 1 Chapter 7 Multiple Division Techniques.
IEEE Wireless LAN Standard
Modulation-Why? 1. Low frequency signal has less energy, which means it can travel less distance. 2. Practibility of antenna.
IE 419/519 Wireless Networks Lecture Notes #6 Spread Spectrum.
CWNA Guide to Wireless LANs, Second Edition Chapter Four IEEE Physical Layer Standards.
EE578 Assignment #5 Abdul-Aziz.M Al-Yami November 8 th 2010.
Stallings, Wireless Communications & Networks, Second Edition, © 2005 Pearson Education, Inc. All rights reserved Spread Spectrum Chapter.
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.
Outline Introduction (Resource Management and Utilization). Compression and Multiplexing (Other related definitions). The Most Important Access Utilization.
F ACULTY OF C OMPUTER S CIENCE & E NGINEERING Chapter 03. Spread Spectrum Technologies.
The University of Iowa. Copyright© 2005 A. Kruger 1 Introduction to Wireless Sensor Networks Wireless Terms, FAQ & Glossary 27 January 2005.
Multiple Access Techniques for Wireless Communications (MAT)
COMMUNICATION SYSTEM EECB353 Chapter 7 Part III MULTIPLE ACCESS Intan Shafinaz Mustafa Dept of Electrical Engineering Universiti Tenaga Nasional
Chapter Thirteen: Multiplexing and Multiple- Access Techniques.
Lecture02 Spread Spectrum Communication By Engr. Muhammad Ashraf Bhutta.
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.
CWNA Guide to Wireless LANs, Second Edition Chapter Four IEEE Physical Layer Standards Modified.
Spread Spectrum Chapter 7.
Wireless Communications. Outline Introduction History System Overview Signals and Propagation Noise and Fading Modulation Multiple Access Design of Cellular.
Data and Computer Communications Eighth Edition by William Stallings Lecture slides by Lawrie Brown Chapter 9 – Spread Spectrum.
Physical Layer (2). Goal Physical layer design goal: send out bits as fast as possible with acceptable low error ratio Goal of this lecture – Review some.
FHSS vs. DSSS Presented by Ali Alhajhouj. Presentation Outline Introduce the issues involved in the system behaviors for FHSS and DSSS systems used in.
Module contents Technologies overview Spread Spectrum Modulation
Lecture 8: Spread Spectrum
1 William Stallings Data and Computer Communications 7 th Edition Chapter 9 Spread Spectrum.
Spread Spectrum Chapter 7. Spread Spectrum Input is fed into a channel encoder Produces analog signal with narrow bandwidth Signal is further modulated.
Wireless & Mobile Networking: Multiple Division Techniques
1 Chapter 7. Spread Spectrum Wen-Shyang Hwang KUAS EE.
King Fahd University of Petroleum & Minerals Electrical Engineering Department EE 578 Simulation of Wireless Systems Code Division Multiple Access Transmission.
Spread Spectrum Input is fed into a channel encoder
Cellular Mobile Communication Systems Lecture 5
Transmission Techniques Traffic channels: different users are assigned unique code and transmitted over the same frequency band, for example, WCDMA and.
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Wireless Communications Principles and Practice 2/e T.S. Rapppaport Chapter.
© 2003, Cisco Systems, Inc. All rights reserved. FWL 1.0—3-1 Wireless Radio Technology Olga Torstensson Halmstad University.
TI Cellular Mobile Communication Systems Lecture 4 Engr. Shahryar Saleem Assistant Professor Department of Telecom Engineering University of Engineering.
The University of Iowa. Copyright© 2005 A. Kruger 1 Introduction to Wireless Sensor Networks Medium Access Control (MAC) 17 February 2005.
CELLULAR COMMUNICATIONS 4. Modulation. Modulation Radio signals can be used to carry information Audio, data, video Information is used to modify.
1 CMPT 371 Data Communications and Networking Spread Spectrum.
IT-101 Section 001 Lecture #15 Introduction to Information Technology.
Wireless specifics. 2 A Wireless Communication System Antenna.
Ad hoc and Sensor Networks Farrukh Aslam Khan, Ph.D. Department of Computer Science FAST-NU Islamabad Office: N-111 E Computer Science Block
Wireless Networks and Spread Spectrum Technologies.
© 2017 SlidePlayer.com Inc. All rights reserved.