L21_channel_access_protocols - Channel Access Protocols...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Channel Access Protocols Lecture 21 6.02 Fall 2008 April 25, 2008 How to share a radio channel Time-Division Multiple Access Contention protocols (Aloha, CSMA) Analysis of utilization (throughput) Channel Access • Broadcast networks: assume everyone can hear everyone else • Examples of broadcast networks: • Most wireless networks incl. WiFi (802.11) • Ethernet (but not 1 Gbit/s or higher) • Goal: Want to share channel efficiently
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 What Does “Efficiently” Mean? • Want high channel utilization • Throughput = Useful data rate (in bits/s or pkts/ s) Utilization = Throughput/Channel Rate • Example: If node i gets n_i bits through in time T, over channel of rate R bits/s, then utilization = ( ! n_i /T) / R • Easy to achieve: just allow one node to send all the time • So… want fairness also • Example: All nodes with data to send should get equal share over time (this is a simplification…) Many Channel Access Protocols • Aka “multiple access” protocols • Time Division Multiple Access (TDMA)
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/23/2009 for the course EECS 6.02 taught by Professor Terman during the Spring '08 term at MIT.

Page1 / 7

L21_channel_access_protocols - Channel Access Protocols...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online