Abstract: Multiple radio transmissions are processed to determine, for each of a number of directions of arrival of the radio transmissions, a most direct direction of arrival, for example, to distinguish a direct path from a reflected path from the target. In some examples, the radio transmissions include multiple frequency components, and channel characteristics at different frequencies are compared to determine the direct path.

Abstract: A system enables a single WiFi access point to localize clients to within tens of centimeters. Such a system can bring indoor positioning to homes and small businesses which typically have a single access point. A key enabler underlying the system is a novel algorithm that can compute sub-nanosecond time of flight using commodity WiFi cards. By multiplying the time of flight with the speed of light, a Wifi access point computes the distance between each of its antennas and the client, hence localizing it. An implementation on commodity WiFi cards demonstrates that the system's accuracy is comparable to state-of-the-art localization systems, which use four or five access points.

Abstract: Directional characterization of a location of a target device makes use of multiple radio transmissions that are received from the target device. In some examples, each radio transmission is received at a first antenna at a fixed location, and is also received at a second moving antenna. The received transmissions are combined to determine the directional characterization, for example, as a distribution of power as a function of direction. In some examples, the received radio transmissions are processed to determine, for each of a plurality of directions of arrival of the radio transmissions, a most direct direction of arrival, for example, to distinguish a direct path from a reflected path from the target.

Abstract: An approach to localization in an indoor environment makes use of a multiple antenna receiver (e.g., in a smartphone, tablet, camera) and knowledge of locations of one or more radio transmitters, which may be part of a data communication infrastructure providing data communication services to devices in the environment. Successive measurements of transmissions from the transmitters are recorded at the receiver as the device is translated and rotated in the environment. Rotation related measurements are also made at the device. The radio frequency and rotation related measurements are used to infer the location and orientation, together referred to as the pose, of the device. Phase synchronization of the transmitters and the receiver are not required. In general, accuracy of the pose estimate far exceeds that achievable using radio frequency measurements without taking into consideration motion of the device, and far exceeds that achievable using the inertial measurements alone.

Abstract: An approach to adaptively positioning a set of mobile routers to provide communication services to a set of clients makes use of estimated direction profiles of communication between routers and clients. The approach does not rely on a Euclidean model in which communication characteristics (e.g., signal strength, data rate, etc.) depend on distance between communicating nodes, and does not necessarily require sampling of communication characteristics in unproductive directions in order to move the routers to preferable locations.

Abstract: An approach to localization in an indoor environment makes use of a multiple antenna receiver (e.g., in a smartphone, tablet, camera) and knowledge of locations of one or more radio transmitters, which may be part of a data communication infrastructure providing data communication services to devices in the environment. Successive measurements of transmissions from the transmitters are recorded at the receiver as the device is translated and rotated in the environment. Rotation related measurements are also made at the device. The radio frequency and rotation related measurements are used to infer the location and orientation, together referred to as the pose, of the device. Phase synchronization of the transmitters and the receiver are not required. In general, accuracy of the pose estimate far exceeds that achievable using radio frequency measurements without taking into consideration motion of the device, and far exceeds that achievable using the inertial measurements alone.

Abstract: A system enables a single WiFi access point to localize clients to within tens of centimeters. Such a system can bring indoor positioning to homes and small businesses which typically have a single access point. A key enabler underlying the system is a novel algorithm that can compute sub-nanosecond time of flight using commodity WiFi cards. By multiplying the time of flight with the speed of light, a Wifi access point computes the distance between each of its antennas and the client, hence localizing it. An implementation on commodity WiFi cards demonstrates that the system's accuracy is comparable to state-of-the-art localization systems, which use four or five access points.

Abstract: An approach to adaptively positioning a set of mobile routers to provide communication services to a set of clients makes use of estimated direction profiles of communication between routers and clients. The approach does not rely on a Euclidean model in which communication characteristics (e.g., signal strength, data rate, etc.) depend on distance between communicating nodes, and does not necessarily require sampling of communication characteristics in unproductive directions in order to move the routers to preferable locations.

Abstract: A distributed wireless communication system includes multiple access points, each with one or more antennas. The access points do not necessarily have synchronized transmitting and receiving radio frequency oscillators. Approaches to channel estimation between the access points and one or more wireless clients account for the lack of synchronization, and do not necessarily require capabilities at the clients that go beyond required or optional features of standard wireless Ethernet (e.g., 802.11n, 802.11g, or 802.11a), thereby supporting “legacy” clients while supporting high data throughput approaches that provide coherent transmission from the multiple antenna of the access points.

Abstract: Directional characterization of a location of a target device makes use of multiple radio transmissions that are received from the target device. In some examples, each radio transmission is received at a first antenna at a fixed location, and is also received at a second moving antenna. The received transmissions are combined to determine the directional characterization, for example, as a distribution of power as a function of direction. In some examples, the received radio transmissions are processed to determine, for each of a plurality of directions of arrival of the radio transmissions, a most direct direction of arrival, for example, to distinguish a direct path from a reflected path from the target.

Abstract: Multiple radio transmissions are processed to determine, for each of a number of directions of arrival of the radio transmissions, a most direct direction of arrival, for example, to distinguish a direct path from a reflected path from the target. In some examples, the radio transmissions include multiple frequency components, and channel characteristics at different frequencies are compared to determine the direct path.

Abstract: In one aspect, a distributed coherent transmission system enables transmissions from separate wireless transmitters with independent frequency or clock references to emulate a system where all the transmitters share a common frequency or clock reference. Differences in frequency and/or phase between transmitters are addressed by suitably precoding signals before modulation at one or more of the transmitters based on a synchronizing transmission from one of the transmitters (e.g., a master transmitter) received at a corresponding receiver sharing the frequency or clock reference with each of the one or more transmitters. Such a distributed coherent transmission system can allow N single-antenna transmitters with independent frequency or clock references to emulate a single N-antenna Multi Input Multi Output (MIMO) transmitter, or implement schemes such as distributed superposition coding or lattice codes that require coherence across separate transmitters.

Abstract: A distributed wireless communication system includes multiple access points, each with one or more antennas. The access points do not necessarily have synchronized transmitting and receiving radio frequency oscillators. Approaches to channel estimation between the access points and one or more wireless clients account for the lack of synchronization, and do not necessarily require capabilities at the clients that go beyond required or optional features of standard wireless Ethernet (e.g., 802.11n, 802.11g, or 802.11a), thereby supporting “legacy” clients while supporting high data throughput approaches that provide coherent transmission from the multiple antenna of the access points.

Abstract: In one aspect, a distributed coherent transmission system enables transmissions from separate wireless transmitters with independent frequency or clock references to emulate a system where all the transmitters share a common frequency or clock reference. Differences in frequency and/or phase between transmitters are addressed by suitably precoding signals before modulation at one or more of the transmitters based on a synchronizing transmission from one of the transmitters (e.g., a master transmitter) received at a corresponding receiver sharing the frequency or clock reference with each of the one or more transmitters. Such a distributed coherent transmission system can allow N single-antenna transmitters with independent frequency or clock references to emulate a single N-antenna Multi Input Multi Output (MIMO) transmitter, or implement schemes such as distributed superposition coding or lattice codes that require coherence across separate transmitters.