network operations & administration cs 4592 lecture 18
DESCRIPTION
Network Operations & administration CS 4592 Lecture 18. Instructor: Ibrahim Tariq. Taxonomy of Multiple-Access Protocols. 12-3 CHANNELIZATION. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/1.jpg)
Network Operations & administration CS 4592
Lecture 18
Instructor: Ibrahim Tariq
![Page 2: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/2.jpg)
2
Taxonomy of Multiple-Access Protocols
![Page 3: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/3.jpg)
12.3
12-3 CHANNELIZATION
Channelization is a multiple-access method in which the available bandwidth of a link is shared in time, frequency, or through code, between different stations. In this section, we discuss three channelization protocols.
Frequency-Division Multiple Access (FDMA)Time-Division Multiple Access (TDMA)Code-Division Multiple Access (CDMA)
Topics discussed in this section:
![Page 4: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/4.jpg)
12.4
Figure 12.21 Frequency-division multiple access (FDMA)
![Page 5: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/5.jpg)
12.5
In FDMA, the available bandwidth of the common channel is divided into
bands that are separated by guard bands.
Note
![Page 6: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/6.jpg)
12.6
Time-division multiple access (TDMA)
![Page 7: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/7.jpg)
12.7
In TDMA, the bandwidth is just one channel that is timeshared between different
stations.
Note
![Page 8: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/8.jpg)
12.8
In CDMA, one channel carries all transmissions simultaneously.
Note
![Page 9: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/9.jpg)
12.9
Simple idea of communication with code
![Page 10: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/10.jpg)
12.10
Figure 12.24 Chip sequences
![Page 11: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/11.jpg)
12.11
Figure 12.25 Data representation in CDMA
![Page 12: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/12.jpg)
12.12
Figure 12.26 Sharing channel in CDMA
![Page 13: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/13.jpg)
12.13
Figure 12.27 Digital signal created by four stations in CDMA
![Page 14: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/14.jpg)
12.14
Figure 12.28 Decoding of the composite signal for one in CDMA
![Page 15: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/15.jpg)
12.15
12-2 CONTROLLED ACCESS
In controlled access, the stations consult one another to find which station has the right to send. A station cannot send unless it has been authorized by other stations. We discuss three popular controlled-access methods.
ReservationPollingToken Passing
Topics discussed in this section:
![Page 16: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/16.jpg)
Reservation
• Station needs to make a reservation before sending data
• Time is divided into intervals• In each interval reservation frame goes before
data telling which station has to send data
![Page 17: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/17.jpg)
12.17
Figure 12.18 Reservation access method
![Page 18: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/18.jpg)
Polling• Works with topologies in which one device is
designated as primary station and others are secondary stations
• All data is communicated through Primary station• If primary device has to send data is alerts
secondary by Sending SELECT function• Primary device if not sending continues to Poll
each device • NAK is send is secondary device does not want to
send data
![Page 19: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/19.jpg)
12.19
POLLING Select and poll functions in polling access method
![Page 20: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/20.jpg)
Token Passing
• Works in any topology if Logical ring is created• Special packet called a token is circulated
through the ring. The possession of token gives the station the right to access the channel and send its data
• If no data to send token is passed to next logical station in ring
![Page 21: Network Operations & administration CS 4592 Lecture 18](https://reader036.vdocument.in/reader036/viewer/2022062520/56816334550346895dd3bbd8/html5/thumbnails/21.jpg)
12.21
Figure 12.20 Logical ring and physical topology in token-passing access method