It is increasingly common for people to use client-side devices to communicate via a radio access network (RAN) with other devices, whether those devices are directly connected to the same RAN or to another network (such as another RAN or a transport network, as examples) to which that RAN directly or indirectly provides access. In a typical arrangement, a base station of a RAN may radiate to define a wireless coverage in which mobile stations (such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices) can operate. In turn, each base station is typically coupled with one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet for instance. With this arrangement, a mobile station operating within a coverage area of a base station can engage in air interface communication with the base station and can thereby communicate via the base station with various remote network entities or with other mobile stations.
In practice, communications over the air interface between a base station and a mobile station are structured in accordance with a particular air interface protocol or “radio access technology,” with communications from the base stations to mobile stations defining a “forward link” (or downlink) and communications from the mobile stations to the base station defining a “reverse link” (or uplink). Numerous such protocols are well known in the art, and others may be developed in the future. Examples of existing protocols include CDMA (e.g., 1×RTT, 1×EV-DO), LTE, WiMAX, iDEN, TDMA, AMPS, GSM, GPRS, UMTS, EDGE, microwave, satellite, MMDS, Wi-Fi (e.g., IEEE 802.11), and Bluetooth. Each protocol may define its own procedures for initiation of calls, handoff between coverage areas, and functions related to air interface communication.
Within the context of a RAN, the term “base station” is sometimes used to describe simply a device known as a base transceiver station (BTS), which contains the hardware, antennas, and so forth that actually conduct the over-the-air portion of the communication with the mobile station on behalf of the RAN. At times, however, the term “base station” is used to refer to a combination of (i) one or more BTSs and (ii) a device known as a base station controller (BSC) (or radio network controller (RNC)), which controls the BTS(s) and connects it (them) to the rest of the network. Further, a base station may encompass functions of one or more other RAN entities as well.
In a typical scenario, a mobile station registers with a RAN via a particular BTS, and then operates in what is known as “idle mode” on a carrier frequency in a coverage area provided by that BTS. If another telephone, computer, or other communication device attempts to contact the mobile station, the RAN will typically send the mobile station a page message via at least that particular BTS. The mobile station may respond by requesting and establishing communication on what is known as an air interface traffic channel (or simply a traffic channel), and proceed to conduct the relevant communication. In other instances, the mobile station may itself originate a communication, in which case the mobile station sends the RAN an access-request message in order to request and establish communication on a traffic channel to conduct the relevant communication. In either scenario, after the RAN has established a radio link and allocated a traffic channel for use by the mobile station, the mobile station is said to be operating in what is known as an “active mode” or “connected mode”.
In some instances, once no substantive communication has taken place between the RAN and the mobile station for a certain amount of time, the RAN will typically reclaim the radio resources (including the traffic channel) that it had allocated to that mobile station, in order to make such resources available for other mobile stations in the coverage area. This transition of the mobile station from (i) having radio resources allocated to it to (ii) not having radio resources allocated to it is often referred to as the mobile station transitioning from active to “dormant”. In some cases, a mobile station may be defined as being dormant if the radio link has been released but a data link layer connection still exists. In such cases, a dormant mobile station may transition back to an active mode by acquiring a radio link and beginning to use the existing data link layer connection. In one example, the amount of time allowed by the RAN to elapse between the last use of the traffic channel and the reclaiming of the traffic channel may be determined based on a value that is specified for a system parameter known as a dormancy timer (or active-to-dormant timer).