d and number of levels of precedence acknowledged [24]. The FCC's wireless Enhanced 911 (E911) requirements seek to improve the effectiveness and reliability of wireless 911 services by providing the dispatchers with additional information on wireless 911 calls. The FCC's wireless E911 rules apply to all wireless licensees, broadband Personal Communications Service (PCS) licensees, and certain Specialized Mobile Radio (SMR) licensees. The FCC has divided its wireless E911 program into two phases: Phase I and Phase II. Under Phase I, the FCC requires carriers, within six months of a valid request by a local Public Safety Answering Point (PSAP), to provide the PSAP with the telephone number of the originator of a wireless 911 call and the location of the cell site or base station transmitting the call. Under Phase II, the FCC requires wireless carriers, within six months of a valid request by a PSAP, to begin providing information that is more precise to PSAPs, specifically, the latitude and longitude of the caller. This information must meet FCC accuracy standards, generally to within 50 to 300 meters, depending on the type of technology used. The deployment of E911 requires the development of new technologies and upgrades to local 911 PSAPs, as well as coordination among public safety agencies, wireless carriers, technology vendors, equipment manu- facturers, and local wireline carriers (see http://www.fcc.gov/pshs/services/911-services/enhanced911) 6.9 Mobility and power management 6.9.1 Sleep Mode Operation Sleep is a mode of operation in which an MS conducts pre-negotiated periods of absence from the serving BS air interface. These periods are characterized by the unavailability of the MS, as observed by the serving BS, for DL or UL traffic. Sleep mode is used to minimize MS power consumption and to decrease the use of serving BS radio resources. The Sleep Mode may also be used to support co-located multi-radio coexistence. A single power saving class for each mobile station is managed in order to operate the 