Abstract: Techniques to improve the acquisition process in a spread spectrum environment. The signals from different CDMA systems are spread with different sets of PN sequences, with the PN sequences in each set being uncorrelated to the PN sequences in the other sets. By using uncorrelated PN sequences, the likelihood of detecting a pilot signal from an undesired system is reduced or minimized, and the mean time to acquisition of the pilot signal from the desired system is improved. The mobile station can attempt to acquire the pilot signal by processing the received signal with a first set of PN sequences corresponding to a first hypothesis of the particular signal being acquired. If acquisition of the pilot signal fails, a second set of PN sequences corresponding to a second hypothesis is selected and used to process the received signal. The PN sequences in the second set are uncorrelated to the PN sequences in the first set.

Abstract: Techniques to schedule downlink data transmission to a number of terminals in a wireless communication system. In one method, one or more sets of terminals are formed for possible data transmission, with each set including a unique combination of one more terminals and corresponding to a hypothesis to be evaluated. One or more sub-hypotheses may further be formed for each hypothesis, with each sub-hypothesis corresponding to specific assignments of a number of transmit antennas to the one or more terminals in the hypothesis. The performance of each sub-hypothesis is then evaluated, and one of the evaluated sub-hypotheses is selected based on their performance. The terminal(s) in the selected sub-hypothesis are then scheduled for data transmission, and data is thereafter coded, modulated, and transmitted to each scheduled terminal from one or more transmit antennas assigned to the terminal.

Abstract: A method (18) for scheduling packet data transmissions in a wireless communication system wherein a per-user Priority Function (PF) (24) is based on a channel condition indicated by a Rate Request Indicator (RRI). The method also considers fairness criteria dictated by predetermined Quality of Service (QOS) requirements. In one embodiment, the rate request indicator is a Data Rate Request (DRR). In another embodiment, the rate request indicator is Carrier-to-Interference (C/I) information. In the exemplary embodiment, the base station calculates a Priority Function (PF) for the multiple mobile users. Each PF is a function of the rate request indicator and the projected throughput of a given mobile user. In one embodiment, the predicted throughput is calculated by T′=(T′)&agr;.

Abstract: An improved method and system for terminating dormant mode wireless packet data sessions when a remote network node becomes inaccessible. A wireless subscriber station sends the wireless network a termination notification identifying a packet data session corresponding to a remote network node that has become inaccessible and should be terminated.

Abstract: A method and apparatus which permits handoffs while the mobile station is in the system access state. This is achieved by providing for channel assignment messages to be sent over the paging channel of a plurality of base stations, which increases the probability of one of the messages getting through. In addition, this assures the mobile station will be able handoff to a different base station and have a traffic channel allocated to it on the new base station without delay. In addition, a method and apparatus which permits the mobile station to be directly assigned into a soft handoff state upon traffic channel assignment.

Abstract: The invention presented is a novel method and apparatus for generating PN sequences with an arbitrary number of bits, where the number of bits is provided in parallel with each clock pulse. This allows the sequences to be generated at high speed when needed, and allows parallel processing in the acquisition and demodulation processes. In the invention, the initial values of states are loaded into registers of a parallel PN generator, which immediately generates the next n bits of the PN sequence, where n is an arbitrary number dependent on performance required. Then, a first sub-part of the PN generator of the present invention receives the present state of the PN generator and outputs the state of the PN generator n bits in the future. The output of this first sub-part is then provided to a second sub-part of the generator, which generates the next n bits of the PN sequence. In this fashion, the entire PN sequence can be continuously generated.

Abstract: A turbo code interleaver using linear congruential sequences may be employed as a two-dimensional interleaver in a turbo coder that also includes first and second constituent encoders. The interleaver and the first encoder are each configured to receive input bits. The first encoder produces output symbols therefrom. The interleaver receives the input bits sequentially by row. A linear congruential sequence recursion algorithm within the interleaver serves to pseudo-randomly rearrange, or shuffle, the bits within each row of the interleaver. The bits are then output from the interleaver sequentially by column. The second encoder is configured to receive the interleaved bits from the interleaver. The second encoder produces output symbols therefrom. The two streams of output symbols are multiplexed together, with appropriate puncturing. If desired, the linear congruential recursion sequence can be generated in reverse.

Abstract: The present invention is a novel and improved method and apparatus for performing closed loop power control. A method of implementing reverse link outer loop using only pilot signal is described. Such a method is especially useful when the data signals are only present in short burst such that packet or frame error rates (PER or FER) cannot be estimated accurately. Moreover, since this method provides a mechanism for accurate set point adjustment even without a PER (FER) estimate, it can also be used to improve the accuracy of outer loop performance when such estimate becomes available. The present invention estimates a “pilot bit error rate” (PBER), where each pilot “bit” consists of a number pilot chips distributed over a frame. In addition, it estimates the normalized variance of the signal energy (or C/I) for each packet. In addition, in the preferred embodiment, the average number of fingers in lock is also used to determine the power control set point.

Abstract: Techniques to enable the processing of multiple calls in a spread spectrum communications system. The call processing state machines defined by the CDMA standards (e.g., IS-95 and IS-2000) are modified to include a “traffic channel” substate indicative of the mobile station processing at least one active call. Call control (CC) state machines of various types are also provided to control the processing of the calls. To process one or more calls concurrently, a CC state machine is instantiated upon receiving an indication to process a particular call. The instantiated CC state machine is identified with, and used to control the processing of, the particular call. Upon receiving an indication to process an additional call, another CC state machine can be instantiated for the additional call. Correspondingly, upon receiving a directive to release a call, the call and its instantiated CC state machine are released.

Abstract: Multipath RAKE receiver structure that allows for the concurrent demodulation of multipath signals that arrive at the receiver at arbitrarily low arrival time differences. The fingers are set to be a fixed offset from one another. One finger tracks the shift in the peak of the multipath component and the additional fixed offset fingers follow the tracking.

Abstract: A method and apparatus for selecting a favored transmission slot for communicating non-voice data in conjunction with a voice-data communication. The slot, reflecting a favored power level and transmission rate for transmitting the non-voice data on a supplemental channel, is selected based upon the transmission power levels for voice-data transmitted by a base station to a remote station on a fundamental channel. The favored transmission slot is selected without the remote station messaging information to the base station concerning frequency channel or interference information for the supplemental channel.

Abstract: Collisions between messages simultaneously transmitted by multiple spread-spectrum transmitters are reduced by distributing the transmissions over the available resources of the receiver. The transmitters may be mobile stations and the receiver may be a base station in a CDMA cellular telephone system. Each mobile station uses one or more randomization methods to distribute its transmissions. In the first randomization, the mobile station time-delays its transmissions by a number of chips of the PN code with which it spreads the transmitted signal. A hash function produces the number from an identification number uniquely associated with that mobile station. In a second randomization, the mobile station randomly selects the PN code. In a third randomization, the mobile station inserts a random delay between successive message transmissions or probes if it does not receive an acknowledgement after a predetermined timeout period. A predetermined number of such transmissions is called a probe sequence.

Abstract: A system and method for canceling an echo signal. An input waveform is provided to an acoustic processor, and a determination is made whether the input waveform includes information representative of an echo signal. If the input waveform includes information representative of an echo signal, an output waveform is formed by attenuating a residual waveform with the acoustic processor. The residual waveform is attenuated by an attenuation factor that gradually changes from an initial attenuation value to a final attenuation value during the attenuation step. A system and method for adjusting an acoustic signal from a muted state to an unmuted state by varying an attenuation factor applied to an acoustic signal by an acoustic processor. The acoustic signal is provided to an acoustic processor. An output waveform is formed from the acoustic processor by adjusting the attenuation factor from a muted state to a first attenuation value associated with the non-muted state.

Abstract: A detector is used to sample of set of power measurements of a receive signal. The receive signal may comprise one or more signals from remote users as well as interference. A variance of the set of power measurements is also determined. The variance is compared to an overload threshold value. If the variance exceeds the overload threshold value, for some period of time, the system is declaraed to be operating at a potentially unstable point. In this state, future connection originations are denied.

Abstract: A method, and corresponding apparatus, applies to individual base stations in a wireless communications systems, where each base station performs rate assignment to mobile stations optimally, but independently of the other base stations. Different base stations affect each other through other cell interference, and continuously modify their reversed link rate assignment based on the other—cell interference received and the requested rates from the mobile stations. The base stations converge to a stable condition with uncoordinated optimizations.

Abstract: The present invention is a novel and improved method and system for performing the pilot frequency tracking operation for coherent demodulation in a system employing a gated pilot signal. In particular, the present invention describes a method and apparatus in which two frequency tracking loops operate in parallel. The first frequency tracking loop performs its tracking operation based on the hypothesis that the received pilot is continuous throughout the frame's duration. The second frequency tracking loop performs the tracking operation based on the hypothesis that the received pilot is discontinuous and is only present for a portion of the frame's duration.

Abstract: The present invention provides a method and apparatus for allowing a base station or base station controller to adjust transmissions to fixed location subscribers in closed-loop communication systems. In a closed-loop communication system, a base station exchanges signals with both fixed location and mobile user stations. When a user or subscriber initially registers with the base station, the base station determines a status of this subscriber based on, for example, an electronic serial number transmitted to the base station. The base station compares the electronic serial number to a database (Home Location Register) which determines whether the user corresponds to a fixed station or a mobile station. If the user is a fixed station, then the base station lowers nominal and minimum power level thresholds. Based on the lowered thresholds, the base station thereafter transmits forward link signals to the fixed station at a lower power level.

Abstract: A frame erasure compensation method in a variable-rate speech coder includes quantizing, with a first encoder, a pitch lag value for a current frame and a first delta pitch lag value equal to the difference between the pitch lag value for the current frame and the pitch lag value for the previous frame. A second, predictive encoder quantizes only a second delta pitch lag value for the previous frame (equal to the difference between the pitch lag value for the previous frame and the pitch lag value for the frame prior to that frame). If the frame prior to the previous frame is processed as a frame erasure, the pitch lag value for the previous frame is obtained by subtracting the first delta pitch lag value from the pitch lag value for the current frame. The pitch lag value for the erasure frame is then obtained by subtracting the second delta pitch lag value from the pitch lag value for the previous frame.

Abstract: A base station timing analyzer measures the timing performance of a base station from within the base station coverage area without interruption or degradation of the system performance. The timing analyzer has a dummy signal generation mechanism that produces a dummy signal output based on a universal time input. An antenna couples a signal from an operating base station from a wireless link. A summer sums together the dummy signal and signal from the wireless link. A demodulation element receives the summed signal and searches for and demodulates each of the signals. A comparison unit compares the output of the demodulation element to determine the timing performance of the base station to provide an indication of the absolute time offset of the base station signal.