Abstract: In an antenna diversity environment, the timing offset of the receiver's fingers are based on the timing offset of the received peaks of the base station transmit signals. In a system with non-negligible multipath spacing, the timing offset of the received peaks of the base station transmit signals are not necessarily at the same location. In one embodiment, the demodulating elements for the signal from each base station antenna use the same offset for demodulating and determining an error signal based on pilot signal sampling prior to the timing offset and subsequent to the timing offset. The error signals are averaged and used by a time tracking loop to track the incoming signal. In another embodiment, the demodulating elements for the signal from each base station antenna independently time track the signals with different timing offsets for each finger. The preferred embodiment depends on the method used by the base station to multiplex the data onto multiple transmit antennas.

Abstract: In an antenna diversity environment, the timing offset of the receiver's fingers are based on the timing offset of the received peaks of the base station transmit signals. In a system with non-negligible multipath spacing, the timing offset of the received peaks of the base station transmit signals are not necessarily at the same location. In one embodiment, the demodulating elements for the signal from each base station antenna use the same offset for demodulating and determining an error signal based on pilot signal sampling prior to the timing offset and subsequent to the timing offset. The error signals are averaged and used by a time tracking loop to track the incoming signal. In another embodiment, the demodulating elements for the signal from each base station antenna independently time track the signals with different timing offsets for each finger. The preferred embodiment depends on the method used by the base station to multiplex the data onto multiple transmit antennas.

Abstract: A method and system for communicating a frame of information according to both a continuous transmit format and a discontinuous transmit format. The present invention contemplates transmitting one or more data rates in either a continuous transmit mode (814) or a discontinuous transmit mode (812). The present invention contemplates continuous transmission only for certain data rates, and selection between continuous and discontinuous transmission for other data rates (810). Frames transmitted in the discontinuous transmit mode may be transmitted at a higher transmit power than in the continuous transmit mode (820). In one embodiment, the information is transmitted at a fifty-percent duty cycle during the second half of the frame when in the discontinuous transmit mode (808). During periods of non-transmission, an alternative system may be searched for as a possible candidate for hard handoff (816).

Abstract: A novel and improved method for performing paging is described. In one embodiment of the invention a searcher is used to detect spread spectrum signals. Samples received RF signals are stored in a sample buffer. During standby mode, the samples are gathered during paging slots assigned to the mobile. A set of searches are performed on the samples, and if pilot signals are detected additional demodulation is performed to detect paging messages. The resulting set of demodulation data may be combined to increase detection. After a page message has been detected, additional demodulation resources may be activated to processes more complete page messages, or other information channels. In one embodiment of the invention, the searcher includes a demodulator to perform quick page detection without the use of finger elements to reduce idle mode power consumption.

Abstract: A system is disclosed for use in a wireless communication system to provide an estimated pilot signal. The system includes a receiver and a front-end processing and despreading component in electronic communication with the receiver for despreading a CDMA signal. A pilot estimation component is in electronic communication with the front-end processing and despreading component for estimating an original pilot signal using a Wiener filter to produce a pilot estimate. A demodulation component is in electronic communication with the pilot estimation component and the front-end processing and despreading component for providing demodulated data symbols. The Wiener filter is configured by an offline filter determination process that calculates parameters of the Wiener filter to minimize the mean-square error.

Abstract: A method and system for a handoff in a broadcast communication system is disclosed. A subscriber assisted handoff is impractical in a broadcast communication system due to e.g., a high signaling load, a difficulty to synchronize the broadcast transmission. On the other hand, the small number of broadcast channels enables the subscriber station to perform the handoff autonomously. To streamline the autonomous handoff decision process, several distinct sets of pilot identifiers and rules for transitioning among the sets are defined. To fully integrate broadcast services with the services provided by the cellular telephone systems in a subscriber environment, a methods for various handoff scenarios are analyzed.

Abstract: An apparatus for initiating a welding arc during a welding process includes a power circuit to provide a welding power to a power output, a background circuit to provide a background power to the power output to maintain the welding arc during the arc-starting process, and a controller. The background circuit provides a background voltage to the power output of the welding device and detects when the motion control device has touched the electrode to the workpiece. Upon detection of a short circuit, the controller starts a timer, and enables the power circuit to provide a steady state, or DC, flow of output current to the power output for a predetermined time period to heat both the electrode and the workpiece to lower the start current needed to form the welding arc. The time period may vary depending on the electrode and the workpiece being used.

Abstract: Techniques for canceling pilot interference in a wireless (e.g., CDMA) communication system. A received signal typically includes a number of signal instances (i.e., multipaths). For each multipath desired to be processed, the other multipaths act as interference on the desired multipath. If the pilot is generated based on a known data pattern (e.g., all zeros) and covered with a known channelization code (e.g., a Walsh code of zero), then the pilot in an interfering multipath may be estimated as the spreading sequence at a time offset corresponding to the arrival time of that multipath. The pilot interference from each interference multipath may be estimated based on the spreading sequence for the interfering multipath and the despreading sequence for the desired multipath. The total pilot interference from a number of interfering multipaths may be subtracted from the data component in the desired multipath to provide pilot-canceled data having improved performance.

Abstract: A system is disclosed for use in a wireless communication system to provide an estimated pilot signal. The system includes a receiver and a front-end processing and despreading component in electronic communication with the receiver for despreading a CDMA signal. A pilot estimation component is in electronic communication with the front-end processing and despreading component for estimating an original pilot signal using a Wiener filter to produce a pilot estimate. A demodulation component is in electronic communication with the pilot estimation component and the front-end processing and despreading component for providing demodulated data symbols. The Wiener filter is configured by an offline filter determination process that calculates parameters of the Wiener filter to minimize the mean-square error.

Abstract: An apparatus and method for identifying remote communications transmitted via a repeater from remote communications not transmitted via the repeater. The method comprises the steps of receiving a plurality of signal transmissions originating from a plurality of remote stations, wherein each of the signal transmissions is associated with a call originating from one of the plurality of remote stations; processing the plurality of received signal transmissions to identify received transmissions that include a discriminant applied by a repeater; and designating each of the plurality of received signal transmissions as being transmitted via the repeater if the received signal transmission includes the discriminant.

Abstract: A method and apparatus for frequency tracking is described. The present invention provides a tracking mechanism for removing the effects of error due to frequency offset as well as compensation for frequency error due to doppler in a plurality of multipath signals. Each finger of a RAKE receiver utilizing the present invention will compute a frequency error for that finger. The weighted average of all of these frequency errors is calculated and filtered to provide a control signal for varying the frequency of IF and RF frequency synthesizers, accounting for the common frequency offset seen at each finger. Additionally, each finger is equipped with a rotator for providing frequency adjustment specific to that finger. The frequency of each finger is adjusted through feedback of the frequency error for that finger.

Abstract: Techniques for coherent demodulation in the presence of phase discontinuities is described. In the exemplary embodiment, times when phase discontinuities occur are known apriori by a receiver in which demodulation is being performed. In an alternate embodiment, the discontinuity location is signaled to the receiver in advance by the transmitter which generates the signals being demodulated. A pilot signal is prepared for optimal coherent demodulation by the use of two filters: one capable of withstanding the effects of phase discontinuity; a second providing superior filtering performance than the first so long as phase discontinuities are not present. Both filters are simultaneously operated. However, the superior performing filter is selected for use in demodulation whenever possible.

Abstract: A novel and improved method for performing paging is described. In one embodiment of the invention a searcher is used to detect spread spectrum signals. Samples received RF signals are stored in a sample buffer. During standby mode, the samples are gathered during paging slots assigned to the mobile. A set of searches are performed on the samples, and if pilot signals are detected additional demodulation is performed to detect paging messages. The resulting set of demodulation data may be combined to increase detection. After a page message has been detected, additional demodulation resources may be activated to processes more complete page messages, or other information channels. In one embodiment of the invention, the searcher includes a demodulator to perform quick page detection without the use of finger elements to reduce idle mode power consumption.

Abstract: Techniques for efficiently performing erasure-and-single-error correction block decoding on a received block of symbols previously coded column-wise with an (N, K) linear block code and row-wise with an error detection code (e.g., a CRC code). Initially, each row of the received block is marked as either an erased row or an un-erased row. To perform erasure-and-single-error correction block decoding on the received block, a codeword corresponding to a column of the received block containing an undetected symbol error is initially identified. The location of the symbol error in the codeword is then determined based on a particular block decoding scheme and corresponding to the selected (N, K) block code. The row of the received block containing the symbol error is then marked as an erased row. Block decoding may then be performed for the received block with the newly marked erased row containing the symbol error.

Abstract: A method and system for communicating a frame of information according to both a continuous transmit format and a discontinuous transmit format. The present invention contemplates transmitting one or more data rates in either a continuous transmit mode (814) or a discontinuous transmit mode (812). The present invention contemplates continuous transmission only for certain data rates, and selection between continuous and discontinuous transmission for other data rates (810). Frames transmitted in the discontinuous transmit mode may be transmitted at a higher transmit power than in the continuous transmit mode (820). In one embodiment, the information is transmitted at a fifty-percent duty cycle during the second half of the frame when in the discontinuous transmit mode (808). During periods of non-transmission, an alternative system may be searched for as a possible candidate for hard handoff (816).

Abstract: An apparatus and method for identifying remote communications transmitted via a repeater from remote communications not transmitted via the repeater. The method comprises the steps of receiving a signal transmission 124A from a remote station 112, determining if the signal transmission 124A includes a discriminant applied to the signal transmitted from the remote station 112 and designating the signal transmission 124A as being transmitted via the repeater 120 if the signal transmission 124A includes the discriminant.

Abstract: A method and system for communicating a frame of information according to both a continuous transmit format and a discontinuous transmit format. The present invention contemplates transmitting one or more data rates in either a continuous transmit mode (814) or a discontinuous transmit mode (812). The present invention contemplates continuous transmission only for certain data rates, and selection between continuous and discontinuous transmission for other data rates (810). Frames transmitted in the discontinuous transmit mode may be transmitted at a higher transmit power than in the continuous transmit mode (820). In one embodiment, the information is transmitted at a fifty-percent duty cycle during the second half of the frame when in the discontinuous transmit mode (808). During periods of non-transmission, an alternative system may be searched for as a possible candidate for hard handoff (816).

Abstract: A Method and System for Utilization of an Outer Decoder in a Broadcast Services Communication System is described. An outer decoder and an inner decoder encode a block of information to be transmitted, to improve protection by adding redundancy. The redundancy permits decoding of the information from less than a complete encoded block of information. Consequently, the receiving station determines when sufficient amount of information for successful decoding has been received, and utilizes the time remaining before the next block of information arrives to perform other activities, e.g., hard handoff on a broadcast channel, inter-frequency hard handoff, and other activities. Alternatively, the receiving station can cease reception, thus decrease power consumption. Furthermore, part of the information block may be utilized for transmission of signaling information.

Abstract: A method and system for a handoff in a broadcast communication system is disclosed. A subscriber assisted handoff is impractical in a broadcast communication system due to e.g., a high signaling load, a difficulty to synchronize the broadcast transmission. On the other hand, the small number of broadcast channels enables the subscriber station to perform the handoff autonomously. To streamline the autonomous handoff decision process, several distinct sets of pilot identifiers and rules for transitioning among the sets are defined. To fully integrate broadcast services with the services provided by the cellular telephone systems in a subscriber environment, a methods for various handoff scenarios are analyzed.

Abstract: 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.