Research Article
Scaling Laws of Cognitive Networks
@INPROCEEDINGS{10.1109/CROWNCOM.2007.4549764, author={Mai Vu and Natasha Devroye and Masoud Sharif and Vahid Tarokh}, title={Scaling Laws of Cognitive Networks}, proceedings={2nd International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications}, publisher={IEEE}, proceedings_a={CROWNCOM}, year={2008}, month={6}, keywords={Ad hoc networks Cognitive radio Electronic mail FCC Frequency measurement Licenses Multiple access interference Radio transmitters Spread spectrum communication TV}, doi={10.1109/CROWNCOM.2007.4549764} }- Mai Vu
Natasha Devroye
Masoud Sharif
Vahid Tarokh
Year: 2008
Scaling Laws of Cognitive Networks
CROWNCOM
IEEE
DOI: 10.1109/CROWNCOM.2007.4549764
Abstract
Opportunistic secondary spectrum usage has the potential to dramatically increase spectral efficiency and rates of a network of secondary cognitive users. In this work we consider a cognitive network: n pairs of cognitive transmitter and receiver wish to communicate simultaneously in the presence of a single primary transmitter-receiver link. We assume each cognitive transmitter-receiver pair communicates in a realistic single-hop fashion, as cognitive links are likely to be highly localized in space. We first show that under an outage constraint on the primary link’s capacity, provided that the density of the cognitive users is constant, the sum-rate of the n cognitive links scales linearly with n as n ! 1. This scaling is in contrast to the sum-rate scaling of pn seen in multi-hop ad-hoc networks. We then explore the optimal radius of the primary exclusive region: the region in which no secondary cognitive users may transmit, such that the outage constraint on the primary user is satisfied. We obtain bounds that help the design of this primary exclusive region, outside of which cognitive radios may freely transmit.