Research Group on
Mobile Computing and Wireless Networking

- Introduction -

We are a research group in the Department of Computer Science at the University of Texas at Dallas, headed by professor Ding-Zhu Du . Our focus is the design and analysis of algorithms for optimization problems that occur in wireless networking environments. We seek distributed, autonomous, robust and scalable algorithms for real world applications, but are also concerned that these algorithms have good theoretical merit.

Here are a few of the issues we are considering:

Virtual Backbone Assisted Routing for Ad Hoc Networks

Most existing routing protocols suffer from the "broadcast storm problem". By maintaining a virtual backbone over the physical layer, and running routing protocols over the virtual backbone, we can greatly alleviate this problem.

Related optimization problem: Minimum Connected Dominating Set (MCDS)

Resource-Aware Routing for Wireless Networks

Resource constraint is a serious problem in wireless network design, especially for all-wireless networks. A host with almost depleted power, or a buffer overflow, etc., tends to decrease network capacity. Thus, putting the routing burden on hosts with more available resources is very important.

Related optimization problem: Optimal Resource Allocation

QoS Related Issues

A wireless link is very unreliable when compared to its wired counterpart. Providing QoS routing for multimedia traffic (video/audio) is very challenging. The limited bandwidth of wireless networks makes this problem harder.

Related optimization problem: Channel Allocation and Assignment

Power-Aware Routing in Ad Hoc Wireless Networks

1. Why Power Control?

• Most mobile hosts today operate using batteries
• A significant fraction of the wireless node power is consumed by the wireless network interface cards that are responsible for transmitting packets
• Higher transmission power of one host incurs higher interference to other hosts

2. Benefits from Power Control

• Prolonged battery life and system (network) life
• Admission control, link QoS maintenance, resource allocation, mobility and channel impairment adaptation
• Interference mitigation & network capacity increase
• Efficient handling of mobility (handoffs, etc.) Strategies in each network layer Physical Layer

3. Strategies in each network layer

• Physical Layer
  • Minimum power transmission to maintain links
  • Problem: compute minimum energy consumed per host to maintain k-connected graph
• Data Link Layer
  • Power controlled multiple access, effective retransmission request scheme
• Network Layer - maximize network life time
  • Power consumed by each node must be evenly distributed
  • Total transmitted power for each connection must be minimized
  • Problem: How to solve the dilemma?
• Transport Layer
  • Modify TCP protocol parameters

QoS and Resource Management

• Issues
  • Applications with real-time constraints: multimedia & C2
  • Node mobility and variable connection reliability
• Strategies
  • Consider probabilistic resource availability
  • Adaptive resource management system
• Problems
  • Define probabilistic resource/service model
  • Optimize service distribution and resource allocation