Event collection and Measurement Study of Wireless Sensor Networks

MPhil Thesis Defence


Title: "Event collection and Measurement Study of Wireless Sensor Networks"

By

Mr. Xing Xu


Abstract

A fundamental evolution is witnessed in recent research and development of 
wireless sensor networks (WSNs): the capabilities of the sensor nodes are 
strong enough to support more and more comprehensive applications. At the same 
time, more and more unique challenges have been introduced. In this thesis, we 
present our current research status on two different topics: a novel 
energy-efficient event collection scheme, and a measurement study focusing on 
non-orthogonal multi-channel design of WSNs.

We consider an event collection scenario in a 2D region. Using traditional 
multi-hop routing to report events to a sink node or base station, will result 
in severe imbalanced energy consumption of static sensors. In addition, full 
connectivity among all the static sensors may not be possible in some cases. 
Therefore, we exploit a mobile sensor as the sink node to assist the event 
collection by controlling the movement of the mobile sink to collect static 
sensor readings. A key observation of our work is that an event has 
spatial-temporal correlation. Specifically, the same event can be detected by 
multiple nearby sensors within a period of time. Thus, it is more 
energy-efficient if the mobile sink can selectively communicate with only a 
portion of static sensors, while still collecting all the interested events. We 
discuss the event collection problem by leveraging the mobility of the sink 
node and the spatial-temporal correlation of the event, in favor of maximizing 
the network lifetime with a guaranteed event collection rate.

In addition, another critical issue in WSNs is represented by the network 
throughput. To meet the throughput requirement, researchers propose 
multi-channel design in 802.15.4 networks to better utilize the wireless medium 
and avoid the co-channel interference. We argue that the orthogonality is not 
necessary for multi-channel design in WSNs and investigate the feasibility of 
non-orthogonal channel design. In our experiment, we observe that with 
non-orthogonal transmission, the effect of interference comes from co-channel 
and inter-channel is different, i.e., the inter-channel interference is more 
tolerable. Based on that, we propose a novel scheme DCN (Dynamic CCA-threshold 
for Non-orthogonal transmission) which adjusts the CCA-threshold to enable the 
concurrent transmissions on adjacent non-orthogonal channels and thus improve 
the overall network throughput performance.


Date:			Tuesday, 29 June 2010

Time:			2:00pm – 4:00pm

Venue:			Room 3501
 			Lifts 25/26

Committee Members:	Dr. Qian Zhang (Supervisor)
 			Dr. Yunhao Liu (Chairperson)
 			Dr. Lin Gu


**** ALL are Welcome ****