Abstract: A radio frequency (RF) receiver and method of controlling an RF receiver are provided. The method includes receiving an RF signal and down-converting the RF signal to a substantially baseband signal. A direct current (DC) transition is detected in a portion of the substantially baseband signal. The substantially baseband signal is then filtered using a first filter configuration at the portion of the substantially baseband signal including the DC transition and a second filter configuration at a portion of the substantially baseband signal not including the DC transition.

Abstract: A method of expanding a capacity of a single radio channel, and a radio. The method includes receiving a primary signal and a secondary signal. The method also includes a transmitter modulating the primary signal and the secondary signal. The method further includes the transmitter scaling a power of the secondary signal below a power of the primary signal to create a power differential. The method also includes the transmitter offsetting a carrier frequency of the secondary signal from a carrier frequency of the primary signal to create a carrier frequency offset. The method further includes the transmitter combining the primary signal and the secondary signal to generate a composite signal. The method also includes the transmitter transmitting the composite signal within the single radio channel via an antenna. The antenna is coupled to the transmitter.

Abstract: A method of expanding a capacity of a single radio channel, and a radio. The method includes receiving a primary signal and a secondary signal. The method also includes a transmitter modulating the primary signal and the secondary signal. The method further includes the transmitter scaling a power of the secondary signal below a power of the primary signal to create a power differential. The method also includes the transmitter offsetting a carrier frequency of the secondary signal from a carrier frequency of the primary signal to create a carrier frequency offset. The method further includes the transmitter combining the primary signal and the secondary signal to generate a composite signal. The method also includes the transmitter transmitting the composite signal within the single radio channel via an antenna. The antenna is coupled to the transmitter.

Abstract: A radio frequency (RF) receiver and method of controlling an RF receiver are provided. The method includes receiving an RF signal and down-converting the RF signal to a substantially baseband signal. A direct current (DC) transition is detected in a portion of the substantially baseband signal. The substantially baseband signal is then filtered using a first filter configuration at the portion of the substantially baseband signal including the DC transition and a second filter configuration at a portion of the substantially baseband signal not including the DC transition.

Abstract: Disclosed herein are methods and systems for presenting prioritized incident content. One embodiment takes the form of a method that includes receiving one or more status alerts from one or more public-safety devices associated with one or more public-safety responders. The method also includes correlating one or more of the received status alerts with one or more media sessions involving one or more of the public-safety responders. The method also includes prioritizing one or more of the media sessions based on prioritization criteria that includes the one or more status alerts correlated with those media sessions. The method also includes presenting one or more of the prioritized media sessions in a chronological view on respective user interfaces of one or more public-safety communication devices.

Abstract: Disclosed herein are methods and systems for concurrent narrowband and broadband communication. An embodiment takes the form of a method that involves generating a narrowband public-safety-radio (PSR) signal for transmission on a downlink of a PSR network. The method further involves generating a multicarrier wideband signal for transmission on a downlink of a wireless wide area network (WWAN), where the multicarrier wideband signal includes a null DC subcarrier. The method also involves producing a combined signal that includes the superposition of (i) the narrowband PSR signal centered on a characteristic frequency of the null DC subcarrier and (ii) the multicarrier wideband signal. Additionally, the method involves transmitting the combined signal for receipt of the narrowband PSR signal at the characteristic frequency by at least one public-safety radio and receipt of the multicarrier wideband signal by at least one WWAN access terminal.

Abstract: Disclosed herein are methods and systems for presenting prioritized incident content. One embodiment takes the form of a method that includes receiving one or more status alerts from one or more public-safety devices associated with one or more public-safety responders. The method also includes correlating one or more of the received status alerts with one or more media sessions involving one or more of the public-safety responders. The method also includes prioritizing one or more of the media sessions based on prioritization criteria that includes the one or more status alerts correlated with those media sessions. The method also includes presenting one or more of the prioritized media sessions in a chronological view on respective user interfaces of one or more public-safety communication devices.

Abstract: A very-low intermediate frequency (VLIF) receiver and a method of controlling a VLIF receiver. The method comprises receiving a first signal, the first signal including one or both of an on-channel signal portion and an adjacent channel interferer (ACI) portion; determining that the first signal includes a portion having a strength that is above a threshold; in response to determining that the first signal includes a portion having a strength that is above the threshold, estimating one or more IQ imbalance parameters for at least a portion of the first signal; and compensating for an IQ imbalance in at least the portion of the first signal using the one or more IQ imbalance parameters.

Abstract: A method and apparatus for using erasure to improve signal decoding when data is impacted by an interference event. Embodiments may include receiving in an RF receiver a desired on-channel signal that includes an information signal modulated on to the desired on-channel signal; generating a sampled received signal with an analog-to-digital (A/D) converter; detecting an interference event using an interference detector as well as generating a mask based on the interference event; processing the sampled received signal using the mask to generate decoding data for use by a soft decoder; and, providing the decoding data to the soft decoder.

Abstract: A very-low intermediate frequency (VLIF) receiver and a method of controlling a VLIF receiver. The method comprises receiving a first signal, the first signal including one or both of an on-channel signal portion and an adjacent channel interferer (ACI) portion; determining that the first signal includes a portion having a strength that is above a threshold; in response to determining that the first signal includes a portion having a strength that is above the threshold, estimating one or more IQ imbalance parameters for at least a portion of the first signal; and compensating for an IQ imbalance in at least the portion of the first signal using the one or more IQ imbalance parameters.

Abstract: A method and apparatus for using erasure to improve signal decoding when data is impacted by an interference event. Embodiments may include receiving in an RF receiver a desired on-channel signal that includes an information signal modulated on to the desired on-channel signal; generating a sampled received signal with an analog-to-digital (A/D) converter; detecting an interference event using an interference detector as well as generating a mask based on the interference event; processing the sampled received signal using the mask to generate decoding data for use by a soft decoder; and, providing the decoding data to the soft decoder.

Abstract: Systems, devices, and methods to improve signal detection of a receiver in communication systems, including receiving a signal having one or more distorted versions of a predetermined waveform as well as processing the received signal with a plurality of eigenfilters generated from eigenvectors of a covariance matrix of the predetermined waveform. Further a correlation output is generated by further processing the received signal with at least one matched filter formed from an eigenfiltered version of the predetermined waveform and identifying at least one peak in the correlator output. The peak may be used to improve performance of the receiver.

Abstract: Systems, devices, and methods to improve signal detection of a receiver in communication systems, including receiving a signal having one or more distorted versions of a predetermined waveform as well as processing the received signal with a plurality of eigenfilters generated from eigenvectors of a covariance matrix of the predetermined waveform. Further a correlation output is generated by further processing the received signal with at least one matched filter formed from an eigenfiltered version of the predetermined waveform and identifying at least one peak in the correlator output. The peak may be used to improve performance of the receiver.

Abstract: Embodiments include Direct-Conversion Receiver (DCR) apparatus, and methods for performing automatic frequency control based on a received signal. An initial frequency offset value is selected from a lookup table and applied to the receiver's local oscillator. Digital samples are generated based on the received signal, and stored in a buffer in sequential order. A DC estimator performs multiple iterations of a DC component estimation process. The process includes iteratively applying an analysis window to more recently-stored, buffered samples, in order to identify a set of the buffered samples. Within the set of buffered samples, an intermediate value between the amplitudes of two samples is determined (e.g., samples having the largest and smallest amplitudes). Between at least some of the multiple iterations, the number of samples that defines the size of the analysis window is increased.

Abstract: A technique for a secondary communication system to utilize spectrum designated to another (or primary) communication system is provided. By ranking a plurality of secondary base stations based on base station transmit power, calculated required transmit power and path loss, a set of criteria is developed for selecting a highest ranked secondary base station for operation within a primary's spectrum. The ranking may be adapted based on mobility of the secondary's subscriber; and as such the secondary system communicates within the primary's spectrum using the adaptively ranked base stations. Channel selection may also be ranked. The technique and apparatus allows a cognitive radio (CR) network to operate within an incumbent network's spectrum.

Abstract: A communication system comprises a direct conversion receiver for correcting imbalance errors. The direct conversion receiver receives a radio frequency (RF) signal and converts the RF signal to baseband signals. The direct conversion receiver further translates the baseband signals to digital signals having a direct current (DC) offset and applies a DC offset correction to the digital signals having the DC offset to generate first DC offset corrected signals. An imbalance correction unit of the direct conversion receiver applies an imbalance correction to the first DC offset corrected signals by estimating an error between an average envelope of the first DC offset corrected signals and an average envelope of second DC offset corrected signals. The imbalance correction unit is fixed at initial imbalance parameter values. The direct conversion receiver further updates the initial imbalance parameter values of the imbalance correction unit based on the estimated error for correcting imbalance errors.

Abstract: A method for controlling peak-to-average power ratio prior to amplification by a power amplifier is provided. The peak sample of a signal is predicted, window length is adjusted based on the peak width around the peak sample or subcarriers used to transmit the signal, and the window is subsequently used to clip the samples. A peak suppression window may be applied prior to predicting the peak sample when a set number of samples exceed a predetermined threshold. Window clipping may be deactivated if interference and throughput of the power amplifier is detrimentally affected. A pulse shaping filter may be optimized based on the window clipping to control transmitted signal characteristics. Various thresholds used in the prediction may be initially based on system design and power amplifier linearity and then dynamically adjusted based on an estimation of active subcarriers or of interferers present in the communication system.

Abstract: A channel scanning technique and apparatus provides audio hole suppression in two-way radio communications. Upon detecting the absence of a carrier signal on a priority channel during a priority scan mode of operation, a training waveform is constructed upon returning to the home-channel. The training waveform is applied to audio shaping filters within an audio lineup to suppress transients and minimize or eliminate the occurrence of audio pops at a speaker output thereby reducing the audio hole.

Abstract: A communication system comprises a direct conversion receiver for correcting imbalance errors. The direct conversion receiver receives a radio frequency (RF) signal and converts the RF signal to baseband signals. The direct conversion receiver further translates the baseband signals to digital signals having a direct current (DC) offset and applies a DC offset correction to the digital signals having the DC offset to generate first DC offset corrected signals. An imbalance correction unit of the direct conversion receiver applies an imbalance correction to the first DC offset corrected signals by estimating an error between an average envelope of the first DC offset corrected signals and an average envelope of second DC offset corrected signals. The imbalance correction unit is fixed at initial imbalance parameter values. The direct conversion receiver further updates the initial imbalance parameter values of the imbalance correction unit based on the estimated error for correcting imbalance errors.

Abstract: Efficient frequency spectrum sharing between at least one incumbent communication system(s) (102, 104) and at least one cognitive radio (CR) system (106, 108) is provided. The CR unit includes OFDM detection (216) for detecting the presence of OFDM signals which indicate the presence of an incumbent communication system within the shared spectrum. The CR system (106) updates channel occupancy information in response to the detected OFDM signals so as not to interfere with the incumbent communication systems (102, 104).