Abstract: An apparatus for synchronizing frequency to a symbol timing, the apparatus including: a master oscillator to generate a master clock signal; an interpolator to accumulate a frequency error estimate between a symbol timing frequency and the master clock signal; and a frequency controller to transfer a portion of the frequency error estimate to the master oscillator to obtain a lock between the symbol timing and the master clock signal of the master oscillator in a manner that zeros-out the frequency error estimate.

Abstract: A system and method for beamforming beams including: matching weights T to a distribution of resources for each of the beams based on a traffic variation for each of the beams; calculating, with a signal processor for each of the beams based on the weights T, a power scalar ? and a weighted minimum mean squared error (WMMSE) matrix WWMSE; and transmitting/receiving the beams based on the power scalar ? and the WMMSE matrix WWMSE, where the power scalar ? satisfies a total power constraint of an antenna subsystem.

Abstract: A system and method for beamforming includes providing an antenna including feeds, a coverage area including service areas and data streams for each of the service areas; selecting a cluster of M feeds from the feeds; computing, with a GBBF processor (ground based beam former), M×N weights; generating M feed excitations by distributing the N data streams per the M×N weights; switching an array to transfer a respective one of the M feed excitations to a respective one of the M feeds; and beamforming, with the M feeds of the antenna, N beams. In the method, the N beams are each focused on a respective service area of each of the N data streams, the M×N weights improve the transmitting into the respective service area of each of the N data streams, and at least one of the N beams includes a portion of a plurality of the M feed excitations.

Abstract: A system and method for scheduling a variable stayout distance when beam hopping, the method including providing an illumination area of a satellite and candidate beam centers disposed in the illumination area; measuring a respective scan angle from an antenna boresight to a respective beam center of the candidate beam centers; and determining a reuse factor k for each of the candidate beam centers, based on a proportion of the respective scan angle to a maximum scan angle. Each candidate beam center may be processed sequentially. Prior to adding each candidate beam center to a current beam center set, checking whether a candidate beam center meets the stayout distance criteria from all beam centers already in the beam center set.

Abstract: A system and method for scheduling a variable stayout distance when beam hopping, the method including providing an illumination area of a satellite and candidate beam centers disposed in the illumination area; measuring a respective scan angle from an antenna boresight to a respective beam center of the candidate beam centers; and determining a reuse factor k for each of the candidate beam centers, based on a proportion of the respective scan angle to a maximum scan angle. Each candidate beam center may be processed sequentially. Prior to adding each candidate beam center to a current beam center set, checking whether a candidate beam center meets the stayout distance criteria from all beam centers already in the beam center set.

Abstract: A system and method for beamforming includes providing an antenna including feeds, a coverage area including service areas and data streams for each of the service areas; selecting a cluster of M feeds from the feeds; computing, with a GBBF processor (ground based beam former), M×N weights; generating M feed excitations by distributing the N data streams per the M×N weights; switching an array to transfer a respective one of the M feed excitations to a respective one of the M feeds; and beamforming, with the M feeds of the antenna, N beams. In the method, the N beams are each focused on a respective service area of each of the N data streams, the M×N weights improve the transmitting into the respective service area of each of the N data streams, and at least one of the N beams includes a portion of a plurality of the M feed excitations.

Abstract: A system and method for scheduling a variable stayout distance when beam hopping, the method including providing an illumination area of a satellite and candidate beam centers disposed in the illumination area; measuring a respective scan angle from an antenna boresight to a respective beam center of the candidate beam centers; and determining a reuse factor k for each of the candidate beam centers, based on a proportion of the respective scan angle to a maximum scan angle. Each candidate beam center may be processed sequentially. Prior to adding each candidate beam center to a current beam center set, checking whether a candidate beam center meets the stayout distance criteria from all beam centers already in the beam center set.

Abstract: A system and method for beamforming beams including: matching weights T to a distribution of resources for each of the beams based on a traffic variation for each of the beams; calculating, with a signal processor for each of the beams based on the weights T, a power scalar ? and a weighted minimum mean squared error (WMMSE) matrix WWMSE; and transmitting/receiving the beams based on the power scalar ? and the WMMSE matrix WWMSE, where the power scalar ? satisfies a total power constraint of an antenna subsystem.

Abstract: A system and method for beamforming beams including: matching weights T to a distribution of resources for each of the beams based on a traffic variation for each of the beams; calculating, with a signal processor for each of the beams based on the weights T, a power scalar ? and a weighted minimum mean squared error (WMMSE) matrix WWMSE; and transmitting/receiving the beams based on the power scalar ? and the WMMSE matrix WWMSE, where the power scalar ? satisfies a total power constraint of an antenna subsystem.

Abstract: A system and method for beamforming beams including: matching weights T to a distribution of resources for each of the beams based on a traffic variation for each of the beams; calculating, with a signal processor for each of the beams based on the weights T, a power scalar ? and a weighted minimum mean squared error (WMMSE) matrix WWMSE; and transmitting/receiving the beams based on the power scalar ? and the WMMSE matrix WWMSE, where the power scalar/3 satisfies a total power constraint of an antenna subsystem.

Abstract: A system and method for beamforming includes providing an antenna including feeds, a coverage area including service areas and data streams for each of the service areas; scheduling N data streams of the data streams, selecting a cluster of M feeds from the feeds; computing, with a GBBF processor (ground based beam former), M×N weights; generating M feed excitations by distributing the N data streams per the M×N weights; switching an array to transfer a respective one of the M feed excitations to a respective one of the M feeds; and beamforming, with the M feeds of the antenna, N beams. In the method, the N beams are each focused on a respective service area of each of the N data streams, the M×N weights improve the transmitting into the respective service area of each of the N data streams, and at least one of the N beams includes a portion of a plurality of the M feed excitations.

Abstract: A system and method for scheduling a variable stayout distance when beam hopping, the method including providing an illumination area of a satellite and candidate beam centers disposed in the illumination area; measuring a respective scan angle from an antenna boresight to a respective beam center of the candidate beam centers; and determining a reuse factor k for each of the candidate beam centers, based on a proportion of the respective scan angle to a maximum scan angle. Each candidate beam center may be processed sequentially. Prior to adding each candidate beam center to a current beam center set, checking whether a candidate beam center meets the stayout distance criteria from all beam centers already in the beam center set.

Abstract: Techniques for data transmission include a geostationary earth orbiting satellite that includes a first optical communication system configured to receive forward-direction user data via a forward optical link between the satellite and a stratospheric high-altitude communication device, and a first radio frequency (RF) communication system configured to transmit, via a plurality of RF spot beams, the forward-direction user data. The stratospheric high-altitude communication device includes a second RF communication system configured to receive the forward-direction user data via a plurality of concurrent forward RF feeder links, and a second optical communication system configured to transmit to the satellite, via the forward optical link, the forward-direction user data received via the plurality of forward RF feeder links.

Abstract: A User Equipment and method for transmitting a random-access radio frequency (RF) signal by applying Asynchronous Coded Multiple Access (ACMA) in a communication system employing Orthogonal Frequency Division Multiplexing (OFDM) is described. The method including: encoding an information stream as OFDM symbols using a low rate Forward Error Correction (FEC) coding suitable for Successive Interference Cancellation (SIC) to form a payload; generating a burst, including symbols, by performing an inverse fast Fourier transform on a unique word (UW) multiplexed with the payload; and synchronizing a transmission of each of the symbols of the burst with consecutive symbol-start instants. The UW includes a plurality of Zadoff-Chu (ZC) like sequences disposed in a subset of consecutive symbol-start instants of the burst. A receiver detects burst arrival by searching for consecutive ZC-like sequences. Channel state estimation can be performed by using the UW with additional ZC-like sequences in the burst.

Abstract: A system and method for timing synchronization of satellite switching instants with gateway switching instants is described.

Abstract: Techniques for data transmission include a geostationary earth orbiting satellite that includes a first optical communication system configured to receive forward-direction user data via a forward optical link between the satellite and a stratospheric high-altitude communication device, and a first radio frequency (RF) communication system configured to transmit, via a plurality of RF spot beams, the forward-direction user data. The stratospheric high-altitude communication device includes a second RF communication system configured to receive the forward-direction user data via a plurality of concurrent forward RF feeder links, and a second optical communication system configured to transmit to the satellite, via the forward optical link, the forward-direction user data received via the plurality of forward RF feeder links.

Abstract: Techniques for data transmission including receiving, at a geostationary earth orbiting satellite, forward-direction user data via a forward optical link; transmitting, by the geostationary earth orbiting satellite via multiple radio frequency (RF) spot beams, the forward-direction user data received via the forward optical link; receiving, at a stratospheric high-altitude communication device, forward-direction user data via multiple concurrent forward RF feeder links; transmitting, by the stratospheric high-altitude communication device via the forward optical link, the forward-direction user data received via the forward RF feeder links; transmitting, by each of multiple ground-based feeder RF terminals at a same RF feeder site, a respective one of the forward RF feeder links. At least 95% of forward feeder data throughput for all of the forward RF service link transmissions by the satellite is carried via the forward optical link and the forward RF feeder links.

Abstract: A system and method for timing synchronization with a modified DVB-S2X waveform for a forward beam hopping satellite is described. The method includes: transmitting a channel including a plurality of beams per a Beam Hopping Time Plan (BHTP), wherein each beam includes a discontinuous signal including a superframe including timing markers and a Beam Hopping Forward Synchronization Pattern (BHFSP); receiving a synchronization information, without a loopback beam, for one of the plurality of beams; determining an adjustment period and an adjusted symbol rate for generation of terrestrial switching instants, based on the synchronization information, for a transmission of the plurality of beams such that at least a portion of a respective BHFSP of one of the beams aligns with one of satellite switching instants; and adjusting a timing and symbol rate of the transmission according to the adjustment period and the adjusted symbol rate, respectively.

Abstract: Techniques for data transmission including receiving, at a geostationary earth orbiting satellite, forward-direction user data via a forward optical link; transmitting, by the geostationary earth orbiting satellite via multiple radio frequency (RF) spot beams, the forward-direction user data received via the forward optical link; receiving, at a stratospheric high-altitude communication device, forward-direction user data via multiple concurrent forward RF feeder links; transmitting, by the stratospheric high-altitude communication device via the forward optical link, the forward-direction user data received via the forward RF feeder links; transmitting, by each of multiple ground-based feeder RF terminals at a same RF feeder site, a respective one of the forward RF feeder links. At least 95% of forward feeder data throughput for all of the forward RF service link transmissions by the satellite is carried via the forward optical link and the forward RF feeder links.

Abstract: A system and method for timing synchronization with a modified DVB-S2X waveform for a forward beam hopping satellite is described. The method includes: transmitting a channel including a plurality of beams per a Beam Hopping Time Plan (BHTP), wherein each beam includes a discontinuous signal including a superframe including timing markers and a Beam Hopping Forward Synchronization Pattern (BHFSP); receiving a synchronization information, without a loopback beam, for one of the plurality of beams; determining an adjustment period and an adjusted symbol rate for generation of terrestrial switching instants, based on the synchronization information, for a transmission of the plurality of beams such that at least a portion of a respective BHFSP of one of the beams aligns with one of satellite switching instants; and adjusting a timing and symbol rate of the transmission according to the adjustment period and the adjusted symbol rate, respectively.