ervice provider and the public safety spec- trum manager, authentication is required. This ensures DARPA is funding a number of cognitive science appli- that spectrum use will be accomplished according to cations, including: the XG Program, Adaptive Cogni- acceptable behaviors and that the bill will be paid [36]. tion-Enhanced Radio Teams (ACERT), Disruption For a subleasing capability to exist in a public safety band Tolerant Networking (DTN), Architectures for Cogni- a shut-down-on-command function must be supported tive Information Processing (ACIP), Real World Rea- with a bounded response time. There are three approaches soning (REAL), and DAML. DARPA research dollars to this: continuous spectrum granting beacon, time-based under contract are easily in the tens of millions. Good granting of spectrum, and RTS-CTS-inhibit send. results have been achieved in many of these efforts. Figure 2.4b-5 shows the time-based granting of spectrum, The National Science Foundation (NSF) is also described as a periodic handshake confirming sublease. funding cognitive science applications including grants to Even though public safety organizations may not the Virginia Polytechnic Institute and State University sublease spectrum, other organizations may choose to do (Virginia Tech or VT). Additionally, NSF has sponsored Cognitive radio: The technologies required CHAPTER 2.4b knows it is in a car, that it is morning rush hour, and that Spatially Variant GPS Satellites the path being taken is the same as that of the last 200 Advertisers days of commuting, it can predict being in the vicinity of the owner's office wireless local area network (LAN) within a certain time period. The radio may wait until it is in the office to download e-mail and upload the pic- CRs Geolocation tures of the accident taken a few minutes ago. This is an example of the highest level of management of radio functions (assuming the radio is used for e-mail, photos, etc.). Space and Time Spatially Aware Aware Scheduling Spatial awareness may be used for ene