Wireless networks and devices have rapidly been gaining popularity over their wired counterparts. This popularity, in turn, has been generating an explosive and ever-increasing demand for, and hence creating a shortage of, the radio spectrum. The reason for this foreseen spectrum shortage is reported not to be the scarcity of the radio spectrum but the inefficiency of current spectrum access methods, thus leaving spectrum opportunities along both the time and frequency dimensions that wireless devices can exploit. Fortunately, recent technological advances have made it possible to build software-defined radios (SDRs), which, unlike traditional radios, can switch from one frequency band to another at little or no cost. We propose a MAC protocol, called Opportunistic Spectrum MAC (OS-MAC), for wireless networks equipped with cognitive radios like SDRs. OS-MAC 1) adaptively and dynamically seeks and exploits opportunities in both licensed and unlicensed spectra and along both the time and...
Bechir Hamdaoui, Kang G. Shin