Discontiguous OFDM considerations for dynamic spectrum access in idle TV channels

Sharing spectrum with systems that employ frequency reuse over large geographical areas (e.g., TV stations) provides an opportunity to improve spectrum utilization. The Federal Communications Commission (FCC) is considering such sharing in the TV hands (2004). This technical and regulatory opportunity prompted the IEEE to create a new committee, 802.22, that will develop a wireless regional area network (WRAN) standard for operating on vacant TV channels. This paper quantifies the idle bandwidth in the current TV band assignments; although the TV station information incorporated here is specific to the United States, the methodology and findings should be relevant to a global audience. The methodology for this analysis is distinct from prior literature on spectrum use measurements and offers a complementary perspective. Furthermore, the statistics from the analysis point to the value of systems that can operate on discontiguous portions of the radio spectrum. One approach, a modified form of OFDM here termed Discontiguous OFDM (DOFDM), could be well-suited to this dynamic spectrum access application. This paper provides a preliminary description of a DOFDM prototype and describes special considerations for its implementation