Technology Rationale:

Ultimately, the capacity of the open access bands, and the quality of service they can offer, will depend on the degree to which radios can be designed to adapt to a wide variety of conditions, some of which cannot yet be predicted. For this reason, the emerging technologies that have been called “cognitive radio” are particularly relevant to the open access debate. The cognitive approaches being studied here represent a range of options that encompass methods for discovery and facilitation, as well as competition and collaboration. Further, they also represent a range of cognitive options that are associated with varying levels of hardware and protocol complexity. These approaches will be studied using a combination of fundamental analysis, computer simulation and physical emulation using testbeds already being developed at WINLAB.

Technical Approach:
This investigation begins with the forward-looking assumption that a perfect cognitive radio exists and can confi gure itself to any transceiver type. Under this assumption, a number of exemplary cognitive strategies are studied to identify the approaches which offer the greatest benefit at the least “cost”. These strategies include:

•discovery of available spectrum,
• information to support effi cient operation,
• negotiation in situations of conflict,
• coding for effi cient sharing, and
• domination in situations of conflict.

Because these strategies are technologically diverse, their costs will be measured against the common metrics of hardware and protocol complexity.

Results To Date and Future Work Plan:
Funded by the NSF, this collaborative project with Lucent Technologies will identify features that are essential for a good cognitive radio, and in doing so, bring the goal of a realizable cognitive radio closer to reality. Specific projects being studied here include:

• COGNITIVE RADIO PROTOCOLS AND ALGORITHMS FOR OPEN ACCESS: Design of algorithms and protocols for frequency selection, coordination and cooperation among neighbor nodes in a cognitive radio network.

• NETWORK INFORMATION SERVERS FOR OPEN ACCESS: Design of “spectrum servers” that can determine neighborhood and interference information from (potentially anonymous) access point/mobile measurements and reporting, and enable effi cient coordination.

• COOPERATIVE FORWARDING FOR SPECTRUM SHARING: Pricing and game theoretic strategies for incentivizing and enabling cooperation and forwarding, with the added notions of both reputations and virtual currencies to enable open access to spectrum.

• COOPERATIVE CODED TRANSMISSION FOR SPECTRUM SHARING: Cooperative diversity and coding techniques with varying degrees of cognitive awareness and capabilities, for increased spectrum utilization. Exploaration of role of coalition games in cooperative transmission.

• SPECTRUM WARFARE WITH AGILE WAVEFORMS: Primitive distributed control actions and waveform adaptation to strategically teach autonomous radiating nodes in a system to more efficiently share spectrum resources.

Further, the results of this research are of immediate relevance for practitioners in industry, for the large potential user community, and for the civilian and military branches of the government. These results will be disseminated via workshops for practitioners from the private and public sectors, including participants from the Federal Communications Commission, DARPA, and state and local governments interested in the potential benefits of open access to spectrum.