Go Passive to Active- A Survey on Collision Resolution Mechanism in Wireless Sensor Networks

PhD Qualifying Examination


Title: "Go Passive to Active- A Survey on Collision Resolution Mechanism in 
Wireless Sensor Networks"

by

Mr. Xiaoyu Ji


Abstract:

Due to the broadcast nature and lack of collision detection mechanism, 
wireless network suffers from collision. Collision happens when two or 
more packets overlap with each other at receiver side and none of them can 
be received correctly. Collision increases packet delivery delay and 
decreases network throughput because of retransmissions. To tackle 
collision, researchers propose abundant protocols in Medium Access Control 
(MAC) layer. The essential idea behind these protocols is to properly 
coordinate multiple senders to access a shared channel and avoid the case 
when there are two or more senders accessing a shared channel 
simultaneously. There are two ways to coordinate multiple senders. CSMA, 
for example, is a contention based MAC layer protocol while TDMA, on the 
other hand is a schedule based protocol. In recent years, an increasing 
number of protocols are invented to resolve or even utilize collision from 
the view of PHY layer. As PHY layer provides more information and 
demonstrates useful properties, e.g. power indicator like RSSI, the effect 
of capture and constructive interference, researchers approach to the 
problem of collision in wireless network from a new way. For example, pure 
collision avoidance is thought to be superficial and too general, and some 
protocols try to tolerate the existence of collision while guarantee the 
performance of network. Some protocols walk even farther- they treat 
collision as a something good and make use of it.

This survey reviews diverse collision resolution protocols. The logical 
roadmap of this survey is the manner in which protocols treat collision. 
Firstly, traditional collision avoidance based MAC layer protocols are 
presented Wireless Senor Networks (WSNs). Secondly, based on the important 
property, e.g. capture and constructive interference exhibited in PHY 
layer, protocols that utilize these properties are analyzed and this 
survey demonstrates how these protocols could tolerate collision with 
little performance degradation. Thirdly, this survey demonstrates several 
protocols that can cancel collision. Last but not least, this survey 
presents some protocols and describe the details of how to make use of 
collision to help improve network performance.


Date:                   Wednesday, 9 January 2013

Time:                   10:00am - 12:00noon

Venue:                  Room 3501
                         lifts 25/26

Committee Members:	Dr. Yunhao Liu (Supervisor)
 			Dr. Ke Yi (Supervisor)
                         Dr. Gary Chan (Chairperson)
 			Dr. Lei Chen


**** ALL are Welcome ****