Dynamic spectrum management in packet networks

New communications technologies and services have created an explosive demand for electromagnetic spectrum. The radio spectrum is a limited resource, the use of which is licensed by governments. Traditionally, spectrum allocations are based around the paradigm of fixed long-term frequency band assignments and do not necessarily ensure spectrum is being used most efficiently at all times, in all areas. To exploit unused spectrum more efficiently, this proposal seeks to design communication systems that adapt to rapidly changing network conditions. Different levels of cooperation and competition in the network will be considered. Innovative use of spectrum investigated in this proposal will aid regulatory bodies as well as service providers in supplying the public with increased capacity for wireless Internet access. The strategic plan for the proposed research involves the development of distributed, multi-layer algorithms for joint medium access control and resource allocation in networks with variable capacities subject to a global resource constraint. Protocols will be devised that jointly optimize end-to-end rates and resource allocation to maximize total network and spectrum utility. Specifically, this proposal aims to address technical issues in radio networks, such as (i) multi-access fading channels; (ii) random packet arrivals and time-frequency allocations; (iii) energy/delay tradeoff in real-time transmissions; and (iv) end-to-end performance management. The multi-wavelet packet modulation (MWPM), introduced recently by the applicant, generalizes orthogonal frequency division multiplexing (OFDM) schemes proposed for adaptation in cognitive radio systems. The investigations will build on the MWPM as the multiple access scheme which provides flexible time-frequency tiling of the temporal spectrum. The research will impact the direction of the development of new radio network architectures and will be applicable to any radio system, from wireless to cable modems, implementing adaptive modulation schemes and the cross-layer network protocol design.