The use of access terminals (ATs) such as cellular telephones, personal digital assistants, pagers, or portable computers has become an increasingly popular means of communicating with others, accessing information, conducting business, and performing myriad other activities. ATs typically communicate with radio access networks (RANs) over a radio frequency (RF) air interface, using any of a number of communication protocols, such as the evolution-data optimized standard (EV-DO), WiMax, and the code division multiple access method (CDMA).
In a typical RAN, an area is divided geographically into a number of cells and sectors, each defined by a RF radiation pattern from a respective base station in the RAN. Within each sector (or cell), the base station's RF radiation pattern provides the RF air interface over which ATs may communicate with the RAN. In turn, the RAN may communicate with one or more other networks, such as the Public Switched Telephone Network (PSTN) or the Internet. Consequently, when an AT is positioned within a coverage area of the RAN (e.g., in a given sector or cell), the AT can communicate with entities on other networks via the RAN.
The RF air interface of any given sector (or cell) in the RAN is typically divided into a plurality of channels for carrying communications between access ATs and the RAN. For example, the RF air interface may include multiple forward-link channels—such as pilot channels, sync channels, paging channels, and forward-traffic channels—for carrying communications from the RAN to ATs. As another example, the RF air interface may also include multiple reverse-link channels—such as access channels and reverse-traffic channels—for carrying communications from the ATs to the RAN. Depending on the wireless technology used, the air interface can be divided into these channels through code division multiplexing (with each channel defined by modulation with one or more specific codes), time division multiplexing (with each channel defined as one or more recurring segments of time), frequency division multiplexing (with each channel defined by modulation with one or more specific frequencies), or through some other mechanism.