NeXt generation/dynamic spectrum access/cognitive radio wireless networks: a survey
Computer Networks: The International Journal of Computer and Telecommunications Networking
Spectrum pooling: an innovative strategy for the enhancement of spectrum efficiency
IEEE Communications Magazine
Comb-type pilot aided channel estimation in non-contiguous OFDM systems for cognitive radio
WiCOM'09 Proceedings of the 5th International Conference on Wireless communications, networking and mobile computing
Practical implementation of blind synchronization in NC-OFDM based cognitive radio networks
Proceedings of the 2010 ACM workshop on Cognitive radio networks
An architecture for software defined cognitive radio
Proceedings of the 6th ACM/IEEE Symposium on Architectures for Networking and Communications Systems
A highly available spectrum allocation service model in dynamic spectrum market
Future Generation Computer Systems
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Cognitive radios can significantly improve spectrum efficiency by using locally available spectrum. The efficiency, however, depends heavily on their transceiver design. In particular, being able to use non-contiguously aligned spectrum bands simultaneously is a critical requirement. Prior work in this area requires a control channel so that transmitter/receiver pairs can synchronize on their spectrum usage patterns. However, this approach can suffer from high cost and control congestion. In this paper, we propose an in-band solution for informing receivers the spectrum usage patterns. By judiciously designing packet preambles, we embed the spectrum usage patterns in each data packet. Using the legacy 802.11 preamble structure, we focus on choosing the appropriate preamble sequences to maintain reliable packet detection in the presence of noise and interference. We verify our design using simulation and show that it can lead to reliable packet transmissions comparable to those of contiguous spectrum usage. We also identify the impact of interference on our design and propose refinements to choose the preamble sequence using information on the interference.