Broadcast has been a fundamental mechanism to lower down delivery time latency in wireless ad hoc networks. The intrinsic broadcasting nature of radio communications can either speed up the communications by transmitting the message to all neighbors or slow down the communications because of the conflicts with other transmissions. Thus, it is crucial to devise the conflict-free broadcast schedule, especially in mobile ad hoc networks on 3D space. Additionally, as most real networks are dynamic, it is also challenging to develop online algorithms for the broadcast scheduling with a good performance.
Objectives:
- Devise constant approximation algorithms for broadcast scheduling in mobile ad hoc networks on 3D space
- Design a practical model to cover all interference and mobility scenarios in dynamic networks
- Devise online scheduling algorithms for broadcast in dynamic networks
Group Testing, also known as Pooling Design, is a technique to speed up the detection of affected blood samples within a large sample population in Biology. However, it has rarely been used for network security problems due to the limitations in its conventional models and algorithms. Investigating its advantage for defending the Denial-of-Service (DoS) attacks at different network layers can lead to a series of anti-DoS solutions with theoretical and experimental performance guarantee.
Objectives:
- From theoretical facet, improve Group Testing models and algorithms to enhance the affection detection efficiency
- Combine the developed Group Testing models with Graph Theory, Learning Theory to tackle wired application-layer DoS attacks and wireless reactive Jamming attacks
- Provide efficient routing scheme for unreliable networks, in order to maximize pairwise routing packet delivery ratio and avoid congestions
In 1999, it is discovered that almost real large-scale networks follow the same type of graphs called power law graphs. In these realistic networks, the degree distribution follows the power law distribution, at least asymptotically. The fraction of nodes with degree k is proportional to the reciprocal of k power C where C is a constant named the exponential factor. The emergence of the power law distribution has changed the existing approaches to several optimization problems on networks. Institutively we can get faster algorithms solving a particular problem if we exploit all the properties of the problem as well as the type of networks. However, using the power law distribution in designing new algorithms is challenging and it requires new techniques and approaches. In other direction is to reevaluate the difficulty of the problem in this type of networks. Many problems are proved hard to be solved on general graphs but they may be easier to solve on power law graphs.
Objectives:
- Design faster algorithms to solve several optimization problems that exploit the power law distribution
- Revisit the hardness results of several problems on the new type of networks
- Re-analyze existing solutions on the new network models capturing the power law property
In wireless sensor networks, maintenance the network coverage is one of the most important tasks to guarantee the quality of monitoring results. There are many factors that affect the coverage of wireless sensor networks. In the deploying phase, the full coverage may not be achieved because of random deployment. Then in the operation phase, some sensors may stop working due to the energy depletion or malfunctions. If we have redundant mobile sensor in the monitored area, we can schedule them to necessary locations that set up the coverage. The scheduling algorithm should be fast and light because the resource of sensors is very limited.
Objectives:
- Propose the quality measure to evaluate the coverage quality of wireless sensor networks
- Design fast and light movement scheduling algorithm that relocate mobile sensors to guarantee a specific coverage quality