the 5 GHz band in December 2004, based on a 4 X 3 (Tx X Rx) MIMO radio together with an unspecified OFDM method. By June 2005, a data rate in excess of 10 Gbps was demonstrated by a University of Essex team in the UK, over a 60m line-of-sight link. Three RF bands between 2 and 7 GHz were used to create three concurrent data channels of 1.2, 1.6 and 2.4 Gbps, with each band also supporting a second concurrent channel using polarisation-based frequency reuse. Broad commercial application of 1 Gbps wireless LANs may be anticipated around 2010. Cognitive Radio The concept of a cognitive radio was first introduced by Joseph Miltola and Gerald Maguire in 2000, to represent a wireless device that combines an awareness of the RF environment together with learning and reasoning algorithms that can modify wireless PHY parameters in order to meet user requirements within the constraints of the RF environment. Spectrum agile radios are similar but with the emphasis on spectrum sensing and adaptation rather than on learning and reasoning. Spectrum sensing devices and algorithms are used to detect other users and enable spectrum agile radios to adjust their transmission parameters in response to the presence of other radios. Spectrum agile radios may also exchange sensing data in order to co-operate in making use of transmission opportunities. Another key concept underlying cognitive radio is that of a software defined radio (SDR) in which the digital signal processing functions such as data coding and modulation, are performed in software rather Chapter Fourteen than hardware. This gives a cognitive radio the flexibility to use alternative processing schemes, depending on changing requirements. Radio Frequency Policy Modernisation In December 2002, an FCC Spectrum Policy Review Task Force concluded with a number of recommendations aimed at modernising the regulatory framework to increase access to the RF spectrum, while assuring the freedom of existing licensed services from interference. This review was motivated by the cont