Abstract: Satellites provide connectivity in remote and rural areas as well as providing applications and services elsewhere on earth and in space. Existing satellite networks will be increasingly augmented by ultra-dense deployments of interconnected satellites providing low Earth orbit (LEO) constellations. However, such satellites only offer short-term line-of-sight access requiring ongoing handovers during the duration of a terminal’s access. Accordingly, to exploit these LEO constellations the inventors have established methodologies exploiting distributed massive multiple-input multiple-output technology for a user terminal to be connected to a cluster of LEO satellites.

Abstract: A system and method for allocating transmitter power to subcarriers of a multicarrier signal is provided. First, the subcarriers are transmitted with an initial set of power levels and an initial set of constellation assignments. Next, quantized SNR metric values are measured at the receiver for each subcarrier. The measured subcarrier quantized SNR metric is compared with the respective allocated constellation quantized SNR metric, for determining the excess SNR per subcarrier. The transmitter power of the subcarriers whose excess SNR is above a predetermined threshold is adjusted, while keeping the total transmitter power constant. The transmitter power may be adjusted for increasing throughput or robustness of the system. For increased accuracy, several training frames may be used. Advantageously, only constellations equally spaced, such as square or cross constellations, are used. According to a preferred embodiment, OFDM/DMT multicarrier system use IFFT prescalers in the transmitter power adjustment.

Abstract: A system and method for allocating transmitter power to subcarriers of a multicarrier signal is provided. First, the subcarriers are transmitted with an initial set of power levels and an initial set of constellation assignments. Next, quantized SNR metric values are measured at the receiver for each subcarrier. Following, the measured subcarrier quantized SNR metric is compared with the respective allocated constellation quantized SNR metric, for determining the excess SNR per subcarrier. The transmitter power of the subcarriers whose excess SNR is above a predetermined threshold is adjusted, while keeping the total transmitter power constant. The process may be repeated until a set of predefined expectations is met. The transmitter power may be adjusted for increasing throughput or robustness of the system. For increased accuracy of SNR measurements via BER estimation, several training frames may be used. Advantageously, only constellations equally spaced, such as square or cross constellations, are used.

Abstract: A system for highly accurate radio location of a passive radio beacon coincident with an object to be tracked is disclosed. The beacon directs radio signals to an antenna array located proximate to the warehouse aisles and is positioned such that it receives signals that reflect off the aisle walls grazing angles that are generally less than a maximum, and as such act effectively as mirrors. Ray-tracing techniques may be applied to calculate the response at the antenna array. The multiplicity of reflections may be considered virtual radiating elements setting up a MIMO environment of a plurality of orthogonal modes. Because the location of the beacon is calculated, noise effects can be substantially omitted with an increase in precision of the estimate.