Abstract: A wireless terminal and a first node communicate according to a first radio configuration of a first set of radio configurations supported by the first node. A second radio configuration that is available for a second node that supports a second set of radio configurations that is different from the first set of radio configurations is then identified. The wireless terminal and respective ones of the first and second nodes then simultaneously communicate according to the identified second radio configuration. In other embodiments, a wireless terminal is handed off from a first base station to a second base station based on a determination of whether a common radio configuration is available for the first and second base stations. Related wireless communications systems and wireless terminal apparatus are also described.

Abstract: A communications signal is processed to determine a proportionality relationship between a gain of a first channel (e.g., a pilot channel) and a gain of a second channel (e.g., a traffic channel) from a model of the first channel and information recovered from the second channel according to the model of the first channel. Symbol estimates may be generated from the information received over the second channel based on the determined proportionality relationship. In some embodiments, a gain multiplier may be estimated from information received over the second channel, a channel estimate for the first channel and a noise estimate for the first channel, for example, by generating despread values from the information received over the second channel, processing the despread values according to the channel estimate to generate symbol estimates, and generating the estimate of the gain multiplier from the noise estimate and the symbol estimates. Methods, apparatus and computer program products are provided.

Abstract: A CDMA communication system uses a set of quasi-orthogonal codes to supplement the standard set of Walsh codes used in conventional systems. Users are assigned a code selected from the set of Walsh codes, if available. If the number of users exceeds the number of available Walsh codes, selected users are assigned to quasi-orthogonal codes. The users assigned quasi-orthogonal codes are chosen based on user mobility.

Abstract: A communication system includes a mobile terminal and a base station. The mobile terminal estimates signal quality of a forward link during a first power control group period and determines a power control bit based on the estimated signal quality. The mobile terminal further transmits the power control bit on a reverse link during the first power control group period. The base station receives the power control bit on the reverse link and modifies forward link power based on the power control bit at commencement of a second power control group period.

Abstract: A method of providing push-to-talk and push-to-conference functionality in a CDMA system. Participants, in one embodiment, may be divided into active and inactive participants with active participants assigned a private uplink/downlink channel pair by the communication system. Inactive participants may be assigned a public downlink channel. In one embodiment, silent active participants of a conference or talk session are timed out and the private uplink/downlink channel pair previously assigned to such individuals are released for use elsewhere in the network or by other members of the conference. In a push-to-talk embodiment one private uplink/downlink channel pair may at any given time be passed between the presently active members of the group.

Abstract: In a communications system such as a wireless code division multiple access (CDMA) communications system, an interference-compensated information symbol is generated from a source information symbol based on knowledge of an information symbol and a first code used to generate a first coded signal. The first coded signal and a second coded signal representing the interference-compensated information symbol encoded according to a second code are then concurrently transmitted. In one embodiment, a composite signal is generated from at least one information symbol according to at least one code from a first group of codes of a set of quasi-orthogonal codes. An interference-compensated information symbol is then generated from a source information symbol, the composite signal and a code from a second group of codes of the set of quasi-orthogonal codes.

Abstract: A baseband signal phase-compensation technique offsets undesirable phase shifts, or changes in phase shift, introduced in a transmit signal when changing transmit amplifier operating modes. Such mode changes may, for example, entail switching amplifier stages in and out of an amplification signal path. A phase compensator selectively operates on the baseband signal or signals to subtract out an amount of phase shift equal to the amount of phase shift added by switching one or more additional amplifier stages into the amplification signal path. Compensating baseband signals is this manner may be particularly valuable for the reverse link signal of a mobile terminal operating in a wireless communication environment such as CDMA2000. In such environments, abrupt phase shift changes in the transmit signal associated with transmit signal power control are undesirable.

Abstract: A direct sequence spread spectrum receiver for operating in a multipath fading channel comprises a rake receiver having plural rake fingers. Each rake finger demodulates a received signal from one of plural channel paths. The output of the plural rake fingers are combined. Each rake finger utilizes a select assigned delay to synchronize to a delay of the one channel path. A searcher periodically performs a channel search on the received signal to detect new delays of strongest paths in the channel. Plural trackers, one for each channel path, adjust the select assigned delays between searches performed by the searcher. A delay controller is operatively coupled to the searcher and the trackers. The delay controller compares new delays of the strongest paths from the searcher to the select assigned delays and reassigns one of the select assigned delays with one of the new delays only if the new delay differs from the one select assigned delay more than a predetermined threshold.

Abstract: A receiver for a multi-carrier CDMA system receives a signal transmitted having a known pilot sequence on plural sub-carriers. The system includes plural down-converters for down-converting the received signal to baseband signals. A delay and channel estimator correlates at least one of the baseband signals with a single wideband pilot signal, the single wideband pilot signal including all of the known pilot sequences, to produce an estimate of channel gain and multi-path delay. Plural demodulators, one for each of the plural sub carriers, are operatively coupled to the delay and channel estimator, each for demodulating one of the plural baseband signals using the estimate of channel gain and multi-path delay.

Abstract: A method and system reduce multipath signal interference in a CDMA receiver. The CDMA receiver including parallel first and second RAKE receivers receives a multipath signal. The first RAKE receiver includes a number of individual RAKE fingers, each operating with a defined finger delay matched to a propagation path delay. The output signal from each RAKE finger includes multipath interference. The second RAKE receiver includes a group of RAKE fingers corresponding to each RAKE finger in the first RAKE receiver. Each group of RAKE fingers is configured to produce an estimate of the multipath interference in the output signal generated by the corresponding RAKE finger in the first RAKE receiver. The estimated multipath interference signals are scaled, and then subtracted from the RAKE finger outputs from the first RAKE receiver to reduce multipath interference. Scaling coefficients are adjusted to ensure that such subtraction effectively reduces multipath interference.

Abstract: Multipath delay estimation of a direct sequence spread spectrum (DS-SS) signal transmitted in a multipath fading channel is accomplished by measuring the envelope of the signal to determine a new delay estimate. Delay estimates are also obtained in ray strength order, by subtracting out the influence of the stronger rays on the weaker ones. This subtraction approach can be performed iteratively, allowing further refinement of the delay estimates. Delay estimates can also be determined by minimizing the mean square error (MSE) between a measured correlation function and a modeled correlation function. The minimum mean square error (MMSE) approach can performed iteratively, to further refine the delay estimates. Maximum likelihood (ML) delay estimates can also be obtained by exploiting side information regarding the transmit and receive pulse shapes.

Abstract: The ratio of the delay spread associated with a selected channel to the chip duration is used to determine the number of resolvable paths per carrier in a communication system. A desired number of paths per carrier for the selected channel may then be determined. Next, a number of carriers corresponding to the desired number of paths per carrier may be allocated to the communication signal. Alternatively, a number of carriers for a given channel may be allocated as a function.

Abstract: A method of forward link power control in a CDMA mobile communication system is adapted for diversity transmission. First and second diversity signals are transmitted from a base station to a mobile terminal. The mobile terminal derives first and second channel quality estimates associated with the first and second diversity signals respectively. The mobile terminal uses the channel quality estimates to derive first and second power control codes which it transmits to said base station. The base station adjusts the transmit power of first and second antennas associated with the base station based on the first and second power control codes, respectively.

Abstract: A flexible sliding correlator for use in a spread spectrum receiver divides baseband signal samples into different groups, associates each group with a different section of a spreading code, and combines ones of the signal samples with corresponding values in the spreading code section. The groupings and spreading code sections can be changed during operation of the receiver to maximize performance of the receiver under different or changing conditions. In addition, the sample and spreading code value combinations can be further combined in different ways, and the further combinations can be changed during operation of the receiver. According to another aspect of the invention, the baseband signal can be sampled either uniformly or non-uniformly. The phase and frequency of the baseband sampling can be adjusted during operation of the receiver so that samples are taken very close to the optimum sampling position, at the peak of a chip waveform in the baseband signal.

Abstract: A direct sequence spread spectrum receiver for operating in a multipath fading channel comprises a rake receiver having plural rake fingers. Each rake finger demodulates a received signal from one of plural channel paths. The output of the plural rake fingers are combined. Each rake finger utilizes a select assigned delay to synchronize to a delay of the one channel path. A searcher periodically performs a channel search on the received signal to detect new delays of strongest paths in the channel. Plural trackers, one for each channel path, adjust the select assigned delays between searches performed by the searcher. A-delay controller is operatively coupled to the searcher and the trackers. The delay controller compares new delays of the strongest paths from the searcher to the select assigned delays and reassigns one of the select assigned delays with one of the new delays only if the new delay differs from the one select assigned delay more than a predetermined threshold.

Abstract: A method and apparatus for reducing interpath interference between a first signal and at least one other signal is provided. The invention provides for obtaining a relative phase of the first signal and the at least one other signal, determining an interference component on the first signal caused by the at least one other signal, and removing the interference component from the first signal. The invention is particularly adapted for non-coherent mean-value calculations in a RAKE receiver.

Abstract: A communications signal is processed to determine a proportionality relationship between a gain of a first channel (e.g., a pilot channel) and a gain of a second channel (e.g., a traffic channel) from a model of the first channel and information recovered from the second channel according to the model of the first channel. Symbol estimates may be generated from the information received over the second channel based on the determined proportionality relationship. In some embodiments, a gain multiplier may be estimated from information received over the second channel, a channel estimate for the first channel and a noise estimate for the first channel, for example, by generating despread values from the information received over the second channel, processing the despread values according to the channel estimate to generate symbol estimates, and generating the estimate of the gain multiplier from the noise estimate and the symbol estimates. Methods, apparatus and computer program products are provided.

Abstract: A direct sequence spread spectrum receiver for operating in a multipath fading channel comprises a rake receiver having plural rake fingers. Each rake finger demodulates a received signal from on of plural channel paths. The output of the plural rake fingers are combined. Each rake finger utilizes a select assigned delay to synchronize to a delay of the one channel path. A searcher periodically performs a channel search on the received signal to detect new delays of strongest paths in the channel. Plural trackers, one for each channel path, adjust the select assigned delays between searches performed by the searcher. A delay controller is operatively coupled to the searcher and the trackers. The delay controller compares new delays of the strongest paths from the searcher to the select assigned delays and reassigns one of the select assigned delays with one of the new delays only if the new delay differs from the one select assigned delay more than a predetermined threshold.

Abstract: A method of providing push-to-talk and push-to-conference functionality in a CDMA system. Participants, in one embodiment, may be divided into active and inactive participants with active participants assigned a private uplink/downlink channel pair by the communication system. Inactive participants may be assigned a public downlink channel. In one embodiment, silent active participants of a conference or talk session are timed out and the private uplink/downlink channel pair previously assigned to such individuals are released for use elsewhere in the network or by other members of the conference. In a push-to-talk embodiment one private uplink/downlink channel pair may at any given time be passed between the presently active members of the group.

Abstract: Multiple-mode AMPS system/CDMA system wireless terminals attempt to acquire the CDMA system independent of receiving a Global Action (GA) overhead message from the AMPS system, while continuing to receive paging messages from the AMPS system. In response to the attempt being successful, the multiple-mode AMPS/CDMA wireless terminals transition from the AMPS system to the CDMA system. The attempting may be performed by receiving paging messages from the AMPS systems during spaced apart time intervals and attempting to acquire the CDMA system between the spaced apart time intervals. Specifically, a paging message may be received from a first frame of an AMPS control channel of the AMPS system and an AMPS sleep mode is entered thereafter. CDMA pilot acquisition data may be accumulated during the AMPS sleep mode.