Systematic methodologies for the design of distributed and implementable routing and scheduling algorithms that enable one to design, provision and manage mobile wireless networks with predictable and controllable performance are lacking. The research project provides a new framework for modular cross-layer design of scheduling and routing algorithms for ad-hoc networks.
Clique based methods are used for scheduling, where cliques are defined in the interference graph. Clique based policies are developed to achieve optimal throughput and as basis for distributed implementable algorithms for scheduling. Clique based scheduling is easier and more flexible and provides a pathway to extend Network Calculus results, to provide deterministic performance bounds for wireless networks. For the routing, a component based design model is used that divides the routing protocol into components with separate design concerns. Stability, agility and flexibility are better achieved through a component based architecture. These solutions are still cross-layer, but they have well defined interfaces for signaling, control and information exchange between components and layers. Performance models provide a systematic methodology to study and quantify the relationship and sensitivity of the network performance to its components parameters.
The research will yield new principles and fundamental methodologies for the design, performance evaluation, and control of multi-hop wireless networks. Research results will be incorporated in communication, optimization and design courses at the graduate level. The results will be disseminated to industry and Government Labs. Validation and testing will be accomplished via emulation and real life wireless network testbeds in collaboration with industry and Government Labs.
The research project developed several innovative results about mobile wireless networks, their protocols and performance. A novel cross-layer algorithm for performing jointly routing, scheduling and congestion control was developed based on a general optimization methodology called Network Utility Maximization. Distributed opportunistic scheduling algorithms were developed that exploit the channel fluctuations in wireless adhoc networks; first the channels were probed and then transmissions were scheduled. The project also developed several novel algorithms for energy efficient operation in the so called heterogeneous cellular networks. These involved sophisticated scheduling of power and other resources between macro base stations and mobile pico cells. An innovative way was proposed, developed and implemented for smartphones to share energy and help each other when in need of energy for operation. The research results also included novel methods for establishing trust and security in mobile wireless networks by employing physical (hardware) techniques. Several novel trust establishment and management schemes were developed and evaluated in order to aid collaboration between agents. Fundamental results on network topologies for efficient communications between collaborating agents, network tomography for monitoring networks, and on component-based approaches for protocol design were also developed. The project developed and utilized new methods based on embedding network graphs in hyperbolic space to simplify and solve some of these complex problems. The research results were incorporated into courses and undergraduate projects in systems engineering for networks. Many students went on summer internships with leading companies on industrial projects related to their research on this project. Several graduate students received their PhD degrees from their research in this project and went on to research and development positions with leading telecommunication and social network services companies. The project helped develop an advanced testbed at the University of Maryland for mobile adhoc wireless networks.
