Abstract: Systems and methods for mitigating the effect of in-band interference. The methods comprise: receiving a signal comprising at least one interfering signal component; generating a soft value for each symbol in at least one interfering signal component; and using the soft values to cancel at least one interfering signal component from the signal to mitigate the effect of interference. The soft value represents a most likely value for the symbol which is obtained by: determining a probability metric between an actual value of the symbol and each of a plurality of possible symbol values using a scaling value representing an estimate of the noise level in the signal received by the device; generating current local probabilities for the plurality of possible symbol values using the probability metric; and using the current local probabilities to determine the soft value.

Abstract: Systems and methods comprising: receiving a signal (S) having a first interfering signal component (FISC); generating a replicated SOI (RSOI); and iteratively performing a process to obtain residual errors for FISC. The process involves: modifying an amplitude of RSOI; obtaining a reference signal (RS) by removing RSOI with the modified amplitude from S; analyzing frequency of RS to obtain an estimated carrier frequency and an estimated symbol rate for FISC; generating a remaining signal by removing, from FRS, a signal having the estimated carrier frequency and symbol rate; and determining a residual error of the remaining signal. Parameters for FISC are then set equal to the estimated carrier frequency and symbol rate that are associated with a lowest residual error. The parameters may be further refined in accordance with another process which involves iteratively modifying a symbol rate of FISC. Yet another process may be performed to determine filter parameters.

Abstract: Systems and methods for mitigating the effect of in-band interference. The methods comprise: receiving a signal comprising at least one interfering signal component; generating a soft value for each symbol in at least one interfering signal component; and using the soft values to cancel at least one interfering signal component from the signal to mitigate the effect of interference. The soft value represents a most likely value for the symbol which is obtained by: determining a probability metric between an actual value of the symbol and each of a plurality of possible symbol values using a scaling value representing an estimate of the noise level in the signal received by the device; generating current local probabilities for the plurality of possible symbol values using the probability metric; and using the current local probabilities to determine the soft value.

Abstract: Systems and methods for mitigating an effect interference. The methods comprise: receiving, by a device, a signal comprising a plurality of signal components; determining whether each signal component has a sufficient reconstructability; reconstructing each said signal component that was determined to have sufficient reconstructability using the received signal or an at least partially clean signal with other signal component(s) removed from the received signal; and using the reconstructed signal components to generate a modified received comprising the received signal with the signal components removed therefrom that (i) are devoid of a signal of interest and (ii) have sufficient reconstructability.

Abstract: A Radio Frequency (RF) receiver may include a lower-order phase shift keying (PSK) demodulation circuit configured to generate at least one locking parameter when performing a lower-order PSK demodulation of an RF receive signal having an interfering PSK signal component. A higher-order PSK demodulation circuit has a higher order than the lower-order PSK demodulation circuit, and locks to the RF receive signal using the at least one locking parameter from the lower-order PSK demodulation circuit. The higher-order PSK demodulation circuit performs the higher-order PSK demodulation of the RF receive signal based upon locking to the RF receive signal to determine the interfering PSK signal component.

Abstract: A Radio Frequency (RF) receiver may include a lower-order phase shift keying (PSK) demodulation circuit configured to generate at least one locking parameter when performing a lower-order PSK demodulation of an RF receive signal having an interfering PSK signal component. A higher-order PSK demodulation circuit has a higher order than the lower-order PSK demodulation circuit, and locks to the RF receive signal using the at least one locking parameter from the lower-order PSK demodulation circuit. The higher-order PSK demodulation circuit performs the higher-order PSK demodulation of the RF receive signal based upon locking to the RF receive signal to determine the interfering PSK signal component.

Abstract: Techniques for providing a multi-stage iterative scheme to determine fine granularity estimates of parameters of an interfering signal and for using the fine granularity estimates of the parameters to reduce an impact of the interfering signal against a signal of interest (SOI) are disclosed. An input signal is identified. A first set of estimation parameters that provide a coarse granularity estimate of a center frequency of the jamming signal and of a symbol rate of the jamming signal are determined. The first set of estimation parameters are refined to generate a medium granularity estimate of the center frequency and the symbol rate of the jamming frequency. The medium granularity estimates are also refined to produce a fine granularity estimate of the center frequency and the symbol rate. The fine granularity estimates are used to remove or reduce an influence of the jamming signal on the input signal.

Abstract: Systems and methods for mitigating an effect interference. The methods comprise: receiving, by a device, a signal comprising a plurality of signal components; determining whether each signal component has a sufficient reconstructability; reconstructing each said signal component that was determined to have sufficient reconstructability using the received signal or an at least partially clean signal with other signal component(s) removed from the received signal; and using the reconstructed signal components to generate a modified received comprising the received signal with the signal components removed therefrom that (i) are devoid of a signal of interest and (ii) have sufficient reconstructability.

Abstract: Suppressing interference in a frequency hopping signal. The method includes receiving a frequency hopping signal for a signal of interest. The frequency hopping signal includes the signal of interest modulated using frequency hopping and wideband and narrowband interference. Prior to de-hopping the frequency hopping signal, one or more wideband interferences in the frequency hopping signal are identified. The one or more wideband interferences are suppressed to create a wideband interference suppressed signal. Subsequent to suppressing the one or more wideband interferences, the wideband interference suppressed signal is de-hopped to create a de-hopped signal. In the de-hopped signal, one or more narrowband interferences are identified. The one or more narrowband interferences are suppressed to create an interference suppressed signal. The interference suppressed signal is demodulated to create a demodulated signal.

Abstract: Suppressing interference in a frequency hopping signal. The method includes receiving a frequency hopping signal for a signal of interest. The frequency hopping signal includes the signal of interest modulated using frequency hopping and wideband and narrowband interference. Prior to de-hopping the frequency hopping signal, one or more wideband interferences in the frequency hopping signal are identified. The one or more wideband interferences are suppressed to create a wideband interference suppressed signal. Subsequent to suppressing the one or more wideband interferences, the wideband interference suppressed signal is de-hopped to create a de-hopped signal. In the de-hopped signal, one or more narrowband interferences are identified. The one or more narrowband interferences are suppressed to create an interference suppressed signal. The interference suppressed signal is demodulated to create a demodulated signal.

Abstract: Techniques for providing a multi-stage iterative scheme to determine fine granularity estimates of parameters of an interfering signal and for using the fine granularity estimates of the parameters to reduce an impact of the interfering signal against a signal of interest (SOI) are disclosed. An input signal is identified. A first set of estimation parameters that provide a coarse granularity estimate of a center frequency of the jamming signal and of a symbol rate of the jamming signal are determined. The first set of estimation parameters are refined to generate a medium granularity estimate of the center frequency and the symbol rate of the jamming frequency. The medium granularity estimates are also refined to produce a fine granularity estimate of the center frequency and the symbol rate. The fine granularity estimates are used to remove or reduce an influence of the jamming signal on the input signal.

Abstract: Improved techniques for estimating parameters of a jamming signal. An input signal is identified. This input signal is suspected of being a jammed composite signal. Attributes of a reference signal are determined. The reference signal is an expected signal that was expected to be received. A form fitting operation is performed in which the reference signal is formed fitted with the input signal. The reference signal is subtracted from the input signal to generate an isolated output signal. A suspected portion of the isolated output signal is identified. An estimated symbol rate and an estimated center frequency for the jamming signal are determined based on the suspected portion. The estimated symbol rate and the estimated center frequency are used to facilitate a subsequent mitigation operation of eliminating or reducing an impact of the jamming signal against the signal of interest.

Abstract: One embodiment illustrated herein includes a system for simulating communications in an environment. The system includes a postulated physical environment model, having modeled terrain and continuous changes over time. A channel parameter calculator is coupled to the postulated physical environment model, and configured to obtain samples from the postulated physical environment model, each sample comprising information about modeled terrain at a given time. The channel parameter calculator is further configured to, from the obtained samples, generate communication channel parameters, over time. A channel simulator is coupled to the channel parameter calculator. The channel simulator is configured to be coupled to signal source and to, using the communication channel parameters, apply the communication channel parameters to a communication signal from the signal source to simulate transmission of data through a simulated channel over time.

Abstract: One embodiment illustrated herein includes a system for simulating communications in an environment. The system includes a postulated physical environment model, having modeled terrain and continuous changes over time. A channel parameter calculator is coupled to the postulated physical environment model, and configured to obtain samples from the postulated physical environment model, each sample comprising information about modeled terrain at a given time. The channel parameter calculator is further configured to, from the obtained samples, generate communication channel parameters, over time. A channel simulator is coupled to the channel parameter calculator. The channel simulator is configured to be coupled to signal source and to, using the communication channel parameters, apply the communication channel parameters to a communication signal from the signal source to simulate transmission of data through a simulated channel over time.

Abstract: A block polyphase filter is constructed of a set of filter blocks having different filter functions, and being arranged for parallel processing of portions of an input sequence of signals. Signals of the input sequence are divided among the blocks by a demultiplexer for processing at a clock frequency lower than a clock frequency of the input signal sequence. The filter blocks are arranged in groups, wherein output signals of the blocks in any one group are summed to produce an output signal of the filtered group. Output signals of all of the filter groups are multiplexed to provide an output signal sequence wherein the repetition frequency of the signals may be higher, lower, or equal to the repetition frequency of the input signal sequence depending upon the ratio of the number of filter groups to the number of filter blocks in the set of filter blocks.

Abstract: A circuit 30 for upsampling and upconverting a high rate signal that is divided into M in-phase (I) symbols and M quadrature (Q) symbols. A Nyquist filter 32 upsamples by a factor of k each of the 2M symbols in parallel during one system clock period (CP). The filter 32 has a plurality of 2kM filter components 40, 42, that each provides a continuous output. A plurality of multipliers 50, 52 each upconverts a filter component output with a carrier wave signal 46, 48 that is output from a numerically controlled oscillator 44. A plurality of adders 54 each adds the output of two multipliers 50 to recombine corresponding I and Q samples to output kM samples during a CP. For continuous phase modulation, N parallel bits are input into the filter 32, upsampled in one CP, and accumulated and modulated 82 in parallel in one CP. For analog processing, M (I) and M (Q) symbols are input into an FIR filter 77a, 77b for upsampling, and decimated at a MUX/DAC block 78 for subsequent analog upconversion.

Abstract: A circuit 30 for upsampling and upconverting a high rate signal that is divided into M in phase (I) symbols and M quadrature (Q) symbols. A Nyquist filter 32 upsamples by a factor of k each of the 2M symbols in parallel during one system clock period (CP). The filter 32 has a plurality of 2kM filter components 40, 42, that each provides a continuous output. A plurality of multipliers 50, 52 each upconverts a filter component output with a carrier wave signal 46, 48 that is output from a numerically controlled oscillator 44. A plurality of adders 54 each adds the output of two multipliers 50 to recombine corresponding I and Q samples to output kM samples during a CP. For continuous phase modulation, N parallel bits are input into the filter 32, upsampled in one CP, and accumulated and modulated 82 in parallel in one CP. For analog processing, M (I) and M (Q) symbols are input into an FIR filter 77a, 77b for upsampling, and decimated at a MUX/DAC block 78 for subsequent analog upconversion.

Abstract: A circuit for single or parallel digital fractional interpolation of data samples has a fractional interpolator filter, an oscillator for outputting timing signals to the fractional interpolator filter, and a detector loop with a strobe feedback from the oscillator for outputting a frequency adjustment to the oscillator. Three different approaches are shown to determine the frequency adjustment. One approach is to generate a pulse based on the symbol clock, and measure the differences between the pulse and the strobe and between the strobe and the pulse. The smaller is the frequency adjustment. Another approach is to adjust the strobe period to match the symbol clock period. A third approach is to add an oscillator-driven clock to the symbol clock and integrate the sum over a symbol clock period to generate the frequency adjustment.

Abstract: Disclosed is a method for generating I/Q waveforms for transmission over a CDMA radio channel. The method includes steps of (a) summing, for each of a plurality N of channels, the state of I bits to form an Isum value having a sign bit, the state of Q bits to form a Qsum value having a sign bit, and a total number of active channels to form a channel sum value; (b) applying the Isum value and sign bit, the Qsum value and sign bit, and the channel sum value to an input of a multiplexer; and (c) time multiplexing the inputs to generate first and second sets of output bits. The first set of output bits includes a subset of the Isum value bits, a subset of the Qsum value bits, the I sign bit, and the channel sum value bits. The second set of output bits includes the subset of the Isum value bits, the subset of the Qsum value bits, the Q sign bit, and the channel sum value bits.

Abstract: Users or subscribers of a multi-user communications system, such as a spread spectrum communications system, provide signals to the central station or base unit of that system, and receive signals therefrom. Avoidance of interference among those users' signals is needed to ensure proper operation of the system. To do so, the data of each user is individually scrambled to randomize the data that different users are transmitting, in order to improve tracking performance at a receiver. The data of each user is scrambled independently, in a manner unique to that user in the system, in order to improve tracking performance and detection performance of a receiver. This scrambling makes the multi-user interference zero mean, and makes it possible to integrate out or average out the multi-user interference. The pattern or sequence used for this scrambling, and the pattern or sequence used for spreading here, are preferably identical except in frequency.