Abstract: A radar system processes signals in a flexible, adaptive manner to determine range, Doppler (velocity) and angle of objects in an environment. The radar system processes the received signal to achieve different objectives depending on one or more of a selected range resolution, a selected velocity resolution, and a selected angle of arrival resolution, as defined by memory requirements and processing requirements. The system allows improved resolution of range, Doppler and/or angle depending on the memory requirements and processing requirements.

Abstract: A radar system is described that comprises a transmitter and a receiver. The transmitter transmits radio signals. The receiver receives interfering signals due to local signal coupling of transmitted signals. The local signal coupling comprises at least one interfering path or mechanism. The receiver is configured to output a replica of each of the interfering signals. Each replica is configured to replicate a particular interfering signal received. The receiver is configured to combine into a signal path a replica of an interfering signal to subtract the interfering signal from the signal path. The receiver receives the transmitted radio signals transmitted by the transmitter and reflected from objects in an environment without saturating the signal path due to the subtraction of the interfering signal from the signal path.

Abstract: A radar system has different modes of operation. In one mode, the radar operates as a single-input, multiple output (SIMO) radar system utilizing one transmitted signal from one antenna at a time. Codes with known excellent autocorrelation properties are utilized in this mode. At each receiver the response after correlating with various possible transmitted signals is measured in order to estimate the interference that each transmitter will represent at each receiver. The estimated effect of the interference from one transmitter to a receiver that correlates with a different code is used to mitigate the interference. In another mode, the radar operates as a multi-input, multiple-output (MIMO) radar system utilizing all the antennas at a time. Interference cancellation of the nonideal cross-correlation sidelobes when transmitting in the MIMO mode are employed to remove ghost targets due to unwanted sidelobes.

Abstract: A radar system is described that comprises a transmitter, a receiver, a spillover cancellation unit, and a combiner. The transmitter transmits radio signals. The receiver receives interfering signals due to local signal coupling of transmitted signals. The local signal coupling comprises at least one interfering path or mechanism. The spillover cancellation unit is configured to output a replica of each of the interfering signals. Each replica is configured to replicate a particular interfering signal received through a particular interfering path or mechanism. The combiner is configured to combine into a signal path of the receiver, a replica of an interfering signal to subtract the interfering signal from the receiver's signal path. The receiver receives the transmitted radio signals reflected from objects in the environment without saturating the signal path of the receiver due to the subtraction of the interfering signal from the receiver's signal path.

Abstract: A radar system processes signals in a flexible, adaptive manner to determine range, Doppler (velocity) and angle of objects in an environment. The radar system processes the received signal to achieve different objectives depending on one or more of a selected range resolution, a selected velocity resolution, and a selected angle of arrival resolution, as defined by memory requirements and processing requirements. The system allows improved resolution of range, Doppler and/or angle depending on the memory requirements and processing requirements.

Abstract: A radar system is described that comprises a transmitter, a receiver, a spillover cancellation unit, and a combiner. The transmitter transmits radio signals. The receiver receives interfering signals due to local signal coupling of transmitted signals. The local signal coupling comprises at least one interfering path or mechanism. The spillover cancellation unit is configured to output a replica of each of the interfering signals. Each replica is configured to replicate a particular interfering signal received through a particular interfering path or mechanism. The combiner is configured to combine into a signal path of the receiver, a replica of an interfering signal to subtract the interfering signal from the receiver's signal path. The receiver receives the transmitted radio signals reflected from objects in the environment without saturating the signal path of the receiver due to the subtraction of the interfering signal from the receiver's signal path.

Abstract: A radar system processes signals in a flexible, adaptive manner to determine range, Doppler (velocity) and angle of objects in an environment. The radar system processes the received signal to achieve different objectives depending on the environment, the current information stored in the radar system, and/or external information provided to the radar system. The system allows improved resolution of range, Doppler and/or angle depending on the desired objective.

Abstract: A digital FMCW radar is described that simultaneously transmits and receives digitally frequency modulated signals using multiple transmitters and multiple receivers and associated antennas. Several sources of nearby spillover from transmitters to receivers that would otherwise degrade receiver performance are subtracted by a cancellation system in the analog radio frequency domain that adaptively synthesizes an analog subtraction signal based on residual spillover measured by a correlator operating in the receivers' digital signal processing domains and based on knowledge of the transmitted waveforms. The first adaptive cancellation system achieves a sufficient reduction of transmit-receive spillover to avoid receiver saturation or other non-linear effects, but is then added back in to the signal path in the digital domain after analog-to-digital conversion so that spillover cancellation can also operate in the digital signal processing domain to remove deleterious spillover components.

Abstract: A digital FMCW radar is described that simultaneously transmits and receives digitally frequency modulated signals using multiple transmitters and multiple receivers and associated antennas. Several sources of nearby spillover from transmitters to receivers that would otherwise degrade receiver performance are subtracted by a cancellation system in the analog radio frequency domain that adaptively synthesizes an analog subtraction signal based on residual spillover measured by a correlator operating in the receivers' digital signal processing domains and based on knowledge of the transmitted waveforms. The first adaptive cancellation system achieves a sufficient reduction of transmit-receive spillover to avoid receiver saturation or other non-linear effects, but is then added back in to the signal path in the digital domain after analog-to-digital conversion so that spillover cancellation can also operate in the digital signal processing domain to remove deleterious spillover components.

Abstract: A radar system processes signals in a flexible, adaptive manner to determine range, Doppler (velocity) and angle of objects in an environment. The radar system processes the received signal to achieve different objectives depending on the environment, the current information stored in the radar system, and/or external information provided to the radar system. The system allows improved resolution of range, Doppler and/or angle depending on the desired objective.

Abstract: A satellite broadcasts radio programs to mobile and fixed receivers at various locations. Ground stations supplement the satellite broadcasts in areas where the satellite signal may be shadowed. Likewise, the satellite signal supplements the terrestrial transmissions in areas with marginal terrestrial signal strength. Ground stations and a satellite transmit the same digital symbol stream over a same frequency spectrum. The symbol streams arrive in each service area of the ground stations with a relative delay that is within a window for which a receiver is adapted to decode efficiently. Spectral efficiency is achieved by allowing the ground stations to share the same frequencies as the satellites.

Abstract: A receiver and receive processing method described herein improves the accuracy of channel estimates by correcting for the assumption that the Doppler shift (or rate-of-change-of-delay) stays constant for each frequency within a signal bandwidth of a received signal. To that end, a receiver according to the present invention comprises a channel processor having multiple processing units. A first processing unit processes reference values (e.g., pilot signals) received for each of a plurality of frequencies within a signal bandwidth at a plurality of different signal times (or the complex propagation channel coefficients estimated therefrom) to determine a set of complex wave amplitudes either for each of multiple frequencies in the signal bandwidth or for each of the different signal times.

Abstract: A wire-based infrastructure capable of delivering high data rates is described herein. A transmission system, reception system, and/or repeater uses wire-mapping code matrices to reduce interference in multi-wire cables to increase the data rate provided by such multi-wire cables. More particularly, code mapping matrices are applied to transmission and/or received input signals to generate a mapped signal for each output wire or corresponding to each input wire such that each mapped signal comprises a different combination of all of the input signals. Different ones of the wire-mapped signals are ultimately transmitted on different wires. In so doing, the present invention facilitates crosstalk reduction, and therefore, provides a technique that increases the data rate available on multi-wire cables.

Abstract: Transmitting non-polluting dummy pilot signals in a wireless communication network permits estimation of the downlink propagation channels between a number of joint transmitters and a lesser number of receivers. With fewer receivers than transmitters, loop back information from the receivers is not sufficient to determine the downlink propagation channels between the transmitters and receivers. For N transmitters and M receivers, (N?M) dummy pilot symbols are transmitted to facilitate downlink channel estimation. Each dummy pilot signal is transmitted to an imagined or dummy receiver that is virtually located such that its downlink channel coefficient vector is orthogonal to those of the real receivers. Transmit pre-filtering based on estimated propagation channels is applied to the information signals for the real receivers and to the dummy pilot signals. The extent to which the dummy pilot signals interfere at each receiver is an indication of mismatch between estimated and actual propagation channels.

Abstract: A communication system (20) comprises a transmitter (22) and a receiver (24). The transmitter (22) comprises a source of information symbols (30); a pulse shaping wave function generator (32); and a combiner (34) configured to express the information symbols received from the source as signals which are shaped in time and frequency domains by the wave function. The pulse shaping wave function generator (32) is configured to provide a wave function which has the Nyquist property and has a same shape as its own Fourier transform. The combiner (34) is configured to combine the wave function with a stream of digital data symbols to produce a filtered stream for transmission by the transmitter.

Abstract: A mobile communication network includes an antenna site shared by two or more telecommunications service providers. The antenna site includes a shared resource, such as an antenna, telecommunications equipment, or bandwidth, used by multiple service providers and connects to multiple signal processing centers, each of which belongs to one of the service providers. The signal processing centers may provide modulating signals to the antenna site to use in modulating a carrier. The antenna site may also direct received signals from mobile terminals to the signal processing center for the appropriate service provider. A billing module at the antenna site maintains an accounting of resources used by each service provider.

Abstract: A receiver and receive processing method described herein improves the accuracy of channel estimates by correcting for the assumption that the Doppler shift (or rate-of-change-of-delay) stays constant for each frequency within a signal bandwidth of a received signal. To that end, a receiver according to the present invention comprises a channel processor having multiple processing units. A first processing unit processes reference values (e.g., pilot signals) received for each of a plurality of frequencies within a signal bandwidth at a plurality of different signal times (or the complex propagation channel coefficients estimated therefrom) to determine a set of complex wave amplitudes either for each of multiple frequencies in the signal bandwidth or for each of the different signal times.

Abstract: A method and apparatus for efficiently providing a large volume of channel feedback, e.g., for OFDM MISO and MIMO systems, is described herein. To that end, a mapping unit in an OFDM transceiver maps channel feedback values, e.g., received reference signal values or channel estimates derived therefrom, on a one-to-one basis to individual transmission subchannels. More particularly, the mapping unit maps a feedback value, e.g., the received reference value or a channel estimate derived therefrom, to a single transmission subchannel of an outgoing OFDM signal. For example, the mapping unit may map the feedback value to an input of a frequency transform unit, such as an inverse discrete Fourier transform unit, to map the feedback value to a single transmission subchannel comprising an OFDM transmission subcarrier. The OFDM transceiver transmits the outgoing OFDM signal to the remote transceiver to provide the feedback value to the remote transceiver.

Abstract: A wire-based infrastructure capable of delivering high data rates is described herein. A transmission system, reception system, and/or repeater uses wire-mapping code matrices to reduce interference in multi-wire cables to increase the data rate provided by such multi-wire cables. More particularly, code mapping matrices are applied to transmission and/or received input signals to generate a mapped signal for each output wire or corresponding to each input wire such that each mapped signal comprises a different combination of all of the input signals. Different ones of the wire-mapped signals are ultimately transmitted on different wires. In so doing, the present invention facilitates crosstalk reduction, and therefore, provides a technique that increases the data rate available on multi-wire cables.

Abstract: The technology in this application spreads a signal over an available discontinuous spectrum, such as a radio frequency band, so that the spread signal only occupies the non-contiguous spectrum. In this way, CDMA transmission and reception can be used in a fragmented or non-contiguous spectrum that otherwise would not be useable for direct sequence spreading. Spreading over non-contiguous portions of spectrum is preferably performed without producing unacceptable interference in portions of unavailable spectrum located between the allowed spectrum. By avoiding unacceptable interference in portions of unavailable spectrum located between the allowed spectrum, the unavailable spectrum may be used by other users or services.