摘要:
The certainties of transmitted bits at predetermined locations in time are determine a priori. This information is then used to set the states of a Viterbi decoder to different state metrics in accordance with the certainties of the transmitted bits. High certainty of a transmitted bit results in resetting the states corresponding to that bit to a high state metric. In contrast, low certainty of a transmitted bit results in resetting the states corresponding to that bit to a low state metric. Resetting the states to different state metrics improves the decoding performance and shortens the time required to converge the decoding trellis by eliminating improbable paths.
摘要:
The certainties of transmitted bits at predetermined locations in time are determined a priori. This information is then used to set the states of a Viterbi decoder to different state metrics in accordance with the certainties of the transmitted bits. High certainty of a transmitted bit results in resetting the states corresponding to that bit to a high state metric. In contrast, low certainty of a transmitted bit results in resetting the states corresponding to that bit to a low state metric. Resetting the states to different state metrics improves the decoding performance and shortens the time required to converge the decoding trellis by eliminating improbable paths.
摘要:
A method and apparatus for providing a reliable means to perform handoff from a code division multiple access (CDMA) system using a pilot signal to an alternative access technique system. Simple pilot box circuitry is added to a set of border base stations. The border base stations are base stations which operate only in the alternative access technique and which have coverage areas which are contiguous with coverage areas of CDMA operation base stations. The mobile unit monitors for the pilot signal from the border base stations in the same manner as it monitors for pilot signals from the CDMA operation base stations. When the mobile unit detects the pilot signal corresponding to a border base station, it notifies a system controller in accordance with standard operation. The system controller is aware that the pilot signal corresponds to a border base station and thus triggers a hard handoff process to the alternative access technique system in response thereto. The border base stations use a time division duplex technique to monitor a pilot and synchronization sequence from a neighboring one of the CDMA operation base stations to obtain an estimate of absolute system time.
摘要:
A method and system for providing a reliable means to perform handoff from a code division multiple access (CDMA) system using a pilot signal to an alternative access communication technique system. Simple pilot box circuitry is added to a set of border base stations. The border base stations are base stations which operate only in the alternative access communication technique and which have coverage areas which are contiguous with coverage areas of CDMA operation base stations. The mobile unit monitors for the pilot signal from the border base stations in the same manner as it monitors for pilot signals from the CDMA operation base stations. When the mobile unit detects the pilot signal corresponding to a border base station, it notifies a system controller in accordance with standard operation. The system controller is aware that the pilot signal corresponds to a border base station and thus triggers a hard handoff process to the alternative access communication technique system in response thereto.
摘要:
A system and method for testing signal transmission quality within a digital communication system is disclosed herein. The system may be incorporated within a digital cellular communication system in which information is exchanged over spread spectrum communication channels, among a plurality of mobile users, via at least one cell-site. The system contemplates testing a digital communication channel by transmitting a test sequence of digital data over the communication channel. The test sequence of digital data transmitted over the communication channel is received at a receiving station, within which is also generated a replica of the test sequence of digital data. The accuracy of transmission over the communication channel is then determined by comparing the replica of the test sequence of digital data to the test sequence of data received over the communication channel. The system allows the test sequence of digital data to be transmitted at one of a set of known data rates, with the receive station being disposed to identify the data rate associated with each test sequence of digital data. In a preferred implementation transmission of the test sequence involves generating a first plurality of data packets, which collectively comprise the test sequence of digital data. Each data packet is assigned one of a multiplicity of data rates in accordance with a first pseudorandom process, and is then transmitted at the data rate assigned thereto.
摘要:
A method and circuit for adaptively determining a pilot signal reacquisition time. A searcher subsystem measures a phase of the pilot signal. A control processor measures a magnitude of a shift in the pilot signal phase, compares the measured magnitude to a shift threshold, and decreases the reacquisition time if the measured magnitude is not greater than the shift threshold. The control processor also may compare the reacquisition time to a minimum reacquisition time, and decrease the reacquisition time only if the reacquisition time is greater than the minimum reacquisition time. Additionally, the control processor may increase the reacquisition time to a maximum reacquisition time if the measured magnitude is greater than said shift threshold.
摘要:
The virtual device architecture provides physical and logical device drivers for interfacing software programs executing on a microprocessor of the mobile telephone of a wireless communication system with any of a wide variety of hardware devices connectable within the mobile telephone. The logical device drivers convert commands received from the software applications to commands appropriate for use by selected hardware devices. The physical device drivers receive the converted commands from the logical device drivers and in response to the received commands directly control the selected hardware devices. In one example described herein, the logical device drivers provide translation of core commands necessary to control the selected hardware devices and extended commands for enhanced control of the hardware devices. The logical device drivers operate to convert the extended commands into core commands prior to forwarding the commands to the physical device drivers. By providing logical and physical drivers for use with peripheral devices, the need to provide different versions of software executing on the microprocessor to accommodate different types of peripheral devices is substantially eliminated resulting in a considerable reduction in time and cost associated with developing, maintaining and upgrading software. By providing logical device drivers capable of accommodating both core commands and extended commands, a rich set of peripheral commands can be accommodated thereby further reducing or eliminating the need to provide different versions of software executing on the processor, while nevertheless exploiting the full capabilities of a wide variety of peripheral devices, including state of the art hardware devices such as bit-mapped displays, pointer devices and the like. Method and apparatus embodiments are described.
摘要:
A wireless remote telemetry system which uses low-cost remote communication devices operating on existing wireless communication systems in order to provide real-time reading and control of remote devices. In an embodiment applicable to utility service, consumption of electrical power among a population of customers is measured by a utility metering system having a wireless communication capability. The metering system comprises a remote metering unit which communicates with a central controller over existing wireless communication systems, such as cellular base stations, using existing communication standards. The remote metering unit transmits various messages over a shared random access channel to a central controller. The central controller transmits messages to the remote metering unit over a paging channel. The remote metering unit may operate in a half-duplex mode only. Furthermore, the remote metering unit may provide a gateway to advanced consumer services at the remote location.
摘要:
A method of invoking and canceling voice and data service between a mobile unit and a base station. Using a standard telephone system, the connection for a voice service and a data service is the same. With the introduction of the digital wireless link, the voice connection and the data connection are different. Therefore new dialing commands which indicate the intent of the connection are created. These commands can also be used to designate the intent of the call from a mobile unit capable of data and voice service but not capable of simultaneous voice and data service. They can also be used to invoke simultaneous voice and data services.
摘要:
A method and apparatus for improving searching in a remote unit of a slotted mode, wireless, communication system. In a slotted mode communication system, the remote unit enters an “active state” during its assigned slot. While in the active state, a controller in the remote unit passes selected sets of search parameters to a search engine. The order that the searches are performed is based on the measured signal strength and the age of the measurement. The search engine performs searches using the selected sets of search parameters. Searching continues as long as the remote unit is in the active state. When the remote unit enters the inactive state, searching ceases. While in the inactive state, the controller evaluates the results of the searches performed during the previous active state. During the next active state, the next sequence of searching is performed based on measured signal strength and the measurement age corresponding to the measurements made during the previous active state.