Workpackage 1: Spectrum management for versatile operation of agile networks
Software-defined radio technique was proposed to improve adaptability and flexibility of wireless transmission so that wireless system performance can be enhanced. A cognitive radio transceiver has an ability to observe, learn, optimize, and change the transmission parameters according to the ambient radio environment. With this agility of the radio transceiver, frequency spectrum can be shared among licensed (i.e., primary) and unlicensed (i.e., secondary) services to improve spectrum utilization and also to generate higher revenue to the spectrum owner.
Among the different models for cognitive system, two main approaches have emerged. First framework is commons model. In this approach, primary users are oblivious to the presence of secondary users. Secondary users sense the environment and try to find a spectrum hole for their transmission. In second framework, property-rights (spectrum leasing) model, primary users own the spectral resources and have rights to lease part of it to secondary users in exchange for appropriate revenue.
In this workpackage, we will leverage the new developments in distributed optimization of stochastic networks and game theory to develop efficient management protocols.
Workpackage 2: Topology management for versatile operation of agile networks
We approach cognitive radio as a set of primary users (PUs) that have priority over specific channels whereas secondary users (SUs) can possibly be allowed to exploit these channels either when they are not occupied by PUs or if they can transmit in a way that does not affect the Quality-of-Service (QoS) requirements of PUs. The primary objective of the proposed research topic is to develop distributed strategies for resource allocation in cognitive radio networks, with the goal of maximizing aggregate utility of the SUs balanced against some cost, under the restriction that certain strict QoS constraints of the PU are not violated.
Workpackage 3: Security of agile networks
Future wireless networks with their adaptability to changing conditions and the size of the networking components are extremely vulnerable. On one hand, due to the inherent broadcast nature of wireless medium, all transmissions can essentially be detected by eavesdroppers. In the current wireless LANs, security is not integrated in the network design but instead certain patches are developed for detected vulnerabilities. It is well accepted in the networking and security communities that security should be an integral part of any future networking technology. In this workpackage, we will leverage the new results on information theoretical secrecy to develop dynamic networking protocols.
Workpackage 4: Defining and Provisioning Quality of Service for Heterogeneous Users
Multi-hop wireless networks are envisaged to be very large-scale, highly complex systems typically subject to restrictive and unpredictably changing resource constraints; required to operate using low complexity and scalable operations; envisioned to serve essential applications with a range of long-term (e.g. throughput-greedy, long-duration applications) to short-term (e.g. delay-sensitive, short-duration applications) requirements. In this workpackage, we will develop the necessary mathematical framework and tools for the understanding of the specific problems and the development of protocols investigated in the previous three work packages.