Abstract: The present invention allows many of the benefits of spatial diversity to be realized in a hopping radio communications system. One embodiment of the invention includes transmitting signals from a first radio using a first hopping sequence and transmitting signals from a second radio using spatial processing and a second hopping sequence. The second hopping sequence is coordinated with the first hopping sequence. In another embodiment, the invention includes selecting a set of spatial processing parameters based, at least in part, on a determination whether a third radio using a first frequency resource during a first time interval uses a second frequency resource during a second time interval and transmitting a signal from a first radio to a second radio during the second time interval using the second frequency resource and the selected set of spatial processing parameters.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes collecting measurements of radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, collecting representations of the transmissions of the system user, cross-correlating the collected measurements and the collected representations, and comparing the cross-correlation to the collected measurements to form a characterization of the radio channel traversed by transmissions of the system user.

Abstract: Methods and apparatus for calculating spatial processing strategies in adaptive antenna array processing systems. Reference signal quality, intersymbol interference, data processed and received signal quality can be determined by burst type or remote device type and used to determine a synthetic signal level for use in developing a spatial processing strategy. A synthetic signal have an isotropically distributed component can be added to the antennas in the array or the diagonal elements of the received signal covariance matrix to develop uplink and downlink spatial processing strategies. Different synthetic signals at different signal levels can be used to develop different uplink and downlink spatial processing strategies. The downlink signal level can be larger than the uplink signal level. Uplink and downlink processing strategies can be developed in substantially the same way.

Abstract: An embodiment of the invention provides a method for effecting switchback on a spatial division multiple access (SDMA) PHS channel. A communication signal is broadcast over each of one or more SDMA channels of a multi-access channel to one or more corresponding user terminals. A set of transmit spatial weights is determined for a synchronization burst to a user terminal attempting to reestablish communication over an SDMA channel of the multi-access channel. The set of transmit spatial weights is determined such that interference caused by one or more communication signals to the synchronization burst is reduced.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes measuring radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, accumulating the signal measurements into a first matrix, generating a second matrix representing the transmissions of the system user, cross-correlating the first and second matrices to form a third matrix, and multiplying the third matrix with a product of the second matrix to form a fourth matrix in which the elements of the fourth matrix characterize the radio channel traversed by transmissions of the system user.

Abstract: Embodiments of the invention provide various methods for detecting a spatial division multiple access (SDMA) channel swap. A first SDMA communication channel is assigned to a first user terminal that initially transmits its signal over the first SDMA communication channel. A second SDMA communication channel is assigned to a second user terminal that initially transmits its signal over the second SDMA communication channel. The first user terminal's signal and the second user terminal's signal are analyzed to determine that the first user terminal is transmitting its signal over the second SDMA communication channel and the second user terminal is transmitting its signal over the first SDMA communication channel.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes collecting measurements of radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, collecting representations of the transmissions of the system user, cross-correlating the collected measurements and the collected representations, and comparing the cross-correlation to the collected measurements to form a characterization of the radio channel traversed by transmissions of the system user.

Abstract: Spatial and temporal characteristics of received radio signals in a multiple user radio system can be estimated based on signals received from the users. In one embodiment, the invention includes measuring radio frequency signals received at different elements of an antenna system over time, the received signals corresponding at least in part to transmissions received from a system user, accumulating the signal measurements into a first matrix, generating a second matrix representing the transmissions of the system user, cross-correlating the first and second matrices to form a third matrix, and multiplying the third matrix with a product of the second matrix to form a fourth matrix in which the elements of the fourth matrix characterize the radio channel traversed by transmissions of the system user.

Abstract: A method and apparatus for distinguishing between two or more signals, each associated with a particular remote user terminal, in a shared-channel wireless communication system. A communication device, for example, a base station, causes an offset (e.g., a time and/or a frequency offset) between the transmission of first and second uplink signals that simultaneously occupy the same channel and that are transmitted by first and second remote user terminals, respectively. According to one aspect of the invention, the offset is relatively small enough such that the first and second uplink signals remain within the same channel, but relatively large enough such that based on the offset, the communication device may identify that the first uplink signal is associated with the first remote user terminal.

Abstract: An embodiment of the invention provides a method for effecting switchback on a spatial division multiple access (SDMA) PHS channel. A communication signal is broadcast over each of one or more SDMA channels of a multi-access channel to one or more corresponding user terminals. A set of transmit spatial weights is determined for a synchronization burst to a user terminal attempting to reestablish communication over an SDMA channel of the multi-access channel. The set of transmit spatial weights is determined such that interference caused by one or more communication signals to the synchronization burst is reduced.

Abstract: Embodiments of the invention provide various methods for detecting a spatial division multiple access (SDMA) channel swap. A first SDMA communication channel is assigned to a first user terminal that initially transmits its signal over the first SDMA communication channel. A second SDMA communication channel is assigned to a second user terminal that initially transmits its signal over the second SDMA communication channel. The first user terminal's signal and the second user terminal's signal are analyzed to determine that the first user terminal is transmitting its signal over the second SDMA communication channel and the second user terminal is transmitting its signal over the first SDMA communication channel.

Abstract: A method and apparatus for mitigating co-channel and inter-channel interference in an antenna array system. According to one aspect, the channel-select filter of a base station or other communication device is modified to detect inter-channel interference on at least one non-primary channel when the transmitter is communicating with a remote user terminal on a primary channel. The spatial characteristic of the interference is determined and used to obtain a weight that mitigates the inter-channel interference. According to another aspect, the spatial characteristic of co-channel and/or inter-channel ghost signal interference caused by a transmitter is determined and used to mitigate the effects of such interference.

Abstract: A system and related methods for beamforming in a multi-point communication environment is presented. According to one aspect of the invention, a method comprising identifying one or more target(s) for which a communication signal is intended, identifying one or more other target(s) which may benefit from receipt of the communication signal, and developing a multi-lobe beampattern to transmit the communication signal to the intended target(s) and the identified one or more other target(s).

Abstract: A method and system for providing selective interference mitigation (or nulling) in an adaptive array system. A communication device, typically employing an adaptive array, determines an indication of signal reception quality for a first remote user terminal in communication with the communication device. The communication device provides a first mode of operation wherein a first amount of nulling with respect to at least one interfering source is generated by the communication device. In addition, the communication device provides a second mode of operation characterized by generating a second amount of nulling with respect to the at least one interfering source, wherein the second amount of nulling is relatively greater than the first amount of nulling. Based on the relative signal reception quality indication, the communication device selects one of the first and second modes of operation.

Abstract: A system and related methods for beamforming in a multi-point communication environment is presented. According to one aspect of the invention, a method comprising identifying one or more spatial signature attributes associated with each of a plurality of targets in a wireless communication system, and assigning one or more of the plurality of targets into a cluster based, at least in part, on the identified one or more spatial signature attributes, wherein the target(s) populating a cluster will each share wireless communication channel(s).

Abstract: A system and related methods for introducing intra-channel spatial diversity within a multi-carrier wideband communication channel is presented. In accordance with one aspect of the present invention, developed more fully below, a method is presented comprising receiving information for transmission to a receiver, and generating a plurality of sub-carriers to redundantly transmit the information to a user over a multi-carrier wireless communication channel, wherein each of the sub-carriers is dynamically modified by a set of complex weights to ensure that each of the sub-carriers of the wireless communication channel propagates along a different physical path to the receiver.

Abstract: A method is presented comprising identifying a weak component in a wireless communication link, instructing a transmitter of the weak component to invoke repetition coding, and selectively combining signals received via multiple antennae on multiple channels to recover information contained in the transmitted signal.

Abstract: A method and apparatus for mitigating co-channel and inter-channel interference in an antenna array system. According to one aspect, the channel-select filter of a base station or other communication device is modified to detect inter-channel interference on at least one non-primary channel when the transmitter is communicating with a remote user terminal on a primary channel. The spatial characteristic of the interference is determined and used to obtain a weight that mitigates the inter-channel interference. According to another aspect, the spatial characteristic of co-channel and/or inter-channel ghost signal interference caused by a transmitter is determined and used to mitigate the effects of such interference.

Abstract: A method and apparatus for distinguishing between two or more signals, each associated with a particular remote user terminal, in a shared-channel wireless communication system. A communication device, for example, a base station, causes an offset (e.g., a time and/or a frequency offset) between the transmission of first and second uplink signals that simultaneously occupy the same channel and that are transmitted by first and second remote user terminals, respectively. According to one aspect of the invention, the offset is relatively small enough such that the first and second uplink signals remain within the same channel, but relatively large enough such that based on the offset, the communication device may identify that the first uplink signal is associated with the first remote user terminal.