Abstract:
To access a first communication system, a terminal determines a transmission time for an access probe, an expected response time from the system, and a protected time interval based on the transmission time and/or expected response time. The terminal determines a starting time for sending the access probe such that the protected time interval does not overlap a tune-away interval in which the terminal is to monitor anther frequency/air-interface. This starting time may be set initially to the end of a prior access probe plus a pseudo-random wait duration and may be advanced forward or moved backward in time, if needed, by a time duration selected such that the protected time interval does not overlap the tune-away interval.
Abstract:
An HDLC accelerator includes a deframer and framer to respectively accelerat e the deframing and framing processes for PPP packets. The deframer includes a n input interface unit, a detection unit, a conversion unit, and an output interface unit. The input interface unit receives a packet of data to be deframed. The detection unit evaluates each data byte to detect for special bytes (e.g., flag, escape, and invalid bytes). The conversion unit deframes the received data by removing flag and escape bytes, "un-escaping" the data byte following each escape byte, providing a header word for each flag byte, and checking each deframed packet based on a frame check sequence (FCS) valu e associated with the packet. The output interface unit provides deframed data and may further perform byte alignment in providing the deframed data. A sta te control unit provides control signals indicative of specific tasks to be performed for deframing.
Abstract:
A system and method for determining 1xEV-DO availability for a packet data call in a wireless device is presented. When the wireless device receives a request to initiate a packet data call, the device determines if it currently has access to a preferred 1xEV-DO channel. The determination can be made by consulting a 1xEV-DO availability list stored in persistent memory on the wireless device. If available, the wireless device originates the packet data call on the 1xEV-DO channel. If the device is using a CDMA system that has 1xEV-DO channels but the availability or usability of those channels are unknown, the device polls the signal strength on the 1xEV-DO channels to determine the best 1xEV-DO channel to use for the packet data call. If no 1xEV-DO channel is available or if none of the available 1xEV-DO channels are usable, then the device originates the packet data call on a CDMA channel.
Abstract:
Techniques to efficiently attempt acquisition of a packet data system (e.g., an IS-856 system). If a terminal has acquired one or more channels in a voice/data system (e.g., an IS-2000 system), then it can attempt acquisition on channels in the packet data system that are co-located with the acquired channels in the voice/data system. Multiple acquisition modes may be used, and on-going acquisition attempts on the co-located channels may be performed using one acquisition mode at a time in order to reduce power consumption. Acquisition attempts may be performed in a "ping-pong" manner to improve the likelihood of acquisition. For a ping-pong search, an acquisition attempt is made on the most recently acquired channel prior to an acquisition attempt on each of the remaining channels. Received signal strength estimates may also be obtained for selected channels and may be used to determine whether or not to attempt acquisition on these channels.
Abstract:
Multiple applications sharing common resources are arbitrated such that failures resulting from unavailable resources can be avoided. Whenever an application (e.g., a data application) desires to perform an operation (e.g., PPP resynchronization) that requires the use of a shared resource (e.g., an RF receiver), a determination is made as to whether that resource is available. The operation may be delayed while the resource is unavailable. The application may be assigned the resource if it is available or becomes available and may then start the operation. The resource is locked while the operation is pending to avoid assignment to another application. The resource arbitration allows applications to complete their operations without encountering failures due to other applications taking over the resources.