Gilat Satellite Networks Ltd.

Zih Corporation

Uzi Ram

Oded Bialer

Dubi Lever

Dor Snapir

Izhar Marinov

Guy Sella

Michael Levitsky

Dani Raphaeli

Gideon Kaplan

Ivan Tsonev Ivanov

Guy Levitas

Abraham Menkes

Arik Keshet

Daniel Keschet

Refi Heiman

Tzvi Meiri

Ivan Ivanov

A mobile terminal, operational both to receive and transmit, may comprise a mobile antenna and an antenna controller that may be configured to control the mobile antenna at least for keeping it pointed towards the satellite, e.g. as the mobile terminal and/or the satellite move. Disclosed is a method that may be used by the antenna controller for optimizing the pointing of the mobile antenna, the method may be based on assessing both the reception quality and the transmission quality. This method may be used for overcoming degradation, mainly to transmission quality, that may result from squints between an optimal reception direction and an optimal transmission direction associated with the mobile antenna.

Mobile antenna tracking

The Very Light Readers of the present invention are based on an augmented Tag circuit with a preferred embodiment including at least one VLSI chip integrating a UWB front end, digital transceiver, and possibly an internal controller; a UWB Antenna; a power supply; a controller configured to implement the Media Access Control protocol of the system; a Communication Interface subsystem for connection to the system network and a clock source. Also described is a system capable of reducing collision occurrence in a network for communicating between multiple readers and a plurality of RF Tags. Tags are configured to receive interrogation signals and transmit response signals. Readers are configured to transmit interrogation signals, receive response signals, estimate the quantity of responses received to an interrogation, determine the round trip delay time of each response and estimates whether a collision between responses has occurred. If so, the Reader transmits an additional interrogation signal. The Reader also transmits an acknowledgment packet to responding Tags so responding Tag will not answer again to that broadcast session. Other Readers in the network also receive the acknowledge packet and do not try again to reach the responding Tags, thereby lowering congestion directed toward Tags from multiple Reader transmissions.

Array of very light readers for active RFID and location applications

Satellite communication systems utilize spreading by repetition techniques, including block repetition, to enable operation at low signal to noise conditions. A carrier frequency offset between a transmitter and a receiver results in phase offsets between repetitions. Thus, combining the repetitions requires estimation of the phase offset between the repetitions before coherent de-spreading can be performed. Disclosed herein are methods for estimating a phase offset between successive block repetitions. The methods may utilize more than two repetitions for determining a common phase offset between any two successive repetitions. In some embodiments, these methods may allow summation of repetitions with better coherency and/or with a lower de-spreading loss.

Efficient de-spreading

Methods are presented herein for estimating at least a frequency (offset) for a block of received symbols using two or more estimation stages. These methods may allow reducing the computational complexity of a frequency estimator while maintaining large frequency offset coverage and high frequency estimation accuracy. Also presented herein are satellite communication systems employing a burst transmission or continuous transmission, and configured to estimate at least a frequency (offset) for a received burst or a block of received symbols using two or more estimation stages. In some embodiments, a received burst or a received block of symbols may include a Unique Word located at or about the center of the received burst or the block of symbols.

Efficient frequency estimation

A system and method for packing data over User Packets and packing the User Packets over DVB-S2 Frames, using the DVB-S2-ACM satellite transmission standard.

Packing data over an adaptive rate link

Modern digital signals include framing. A known sequence of transmission symbols (Unique Word (UW)) included in the transmitted signal may be used by a receiver for framing synchronization. A receiver configured to receive such a signal may be configured to detect the UW even when the signal is received with some frequency uncertainty (e.g. offset or error). A method is presented for fast acquisition of symbol and/or frame timing of a signal, including in the presence of frequency uncertainty. In some embodiments, the presented method may be used for determining a frequency offset of the received signal and a location of a unique word (UW) within a frame of the received signal, wherein said determining is based on a two-dimensional search map.

Fast acquisition of frame timing and frequency

This invention presents methods for transmitting and receiving data via a satellite and satellite communication systems thereof. A transmitted signal may include a stream of transmission blocks, whereas each transmission block may differ from a previous transmission block by any of a spreading characteristic, an error correction code-rate characteristic and a modulation characteristic. In addition, any of the spreading, error correction code-rate and modulation characteristics may be changed in accordance with momentary reception conditions at a receiving station.

Adaptive spreading, modulation, and coding

An outgoing transmission carrier frequency at, for example, a remote terminal, may be adjusted based on a feature rate of an incoming transmission. The adjustment may compensate for error in the outgoing transmission carrier frequency. The incoming transmission may be from a satellite or hub, for example. The outgoing transmission may be the signal that is transmitted by an antenna, or the outgoing transmission may be converted to be at another carrier frequency such as a higher carrier frequency for ultimate transmission by an antenna. Also, a remote terminal may be synchronized to a satellite network with or without knowledge of the remote terminals' geographical location and with or without time stamps.

Frequency and timing synchronization and error correction in a satellite network

A system and method for satellite based controlled ALOHA is provided. The system and method configure VSATs so that they accept guidance from a centralized and/or distributed system controller to determine when, where, and/or on what portion of a satellite resource to attempt to access a channel. The system and method take advantage of traffic patterns to maximize efficiency by utilizing a centralized and/or distributed control to determine which VSATs are and are not currently active, and to allocate to a portion of the inbound channel to the active VSATs and a portion of the inbound channel to the inactive VSATs. In a distributed approach, each VSAT decides for itself whether it captures a certain part of the inbound resource or not. This decision can be made based on previous transmissions that went through the part of the inbound intended to be captured.

Growing community of inventors

Givat Elah, Israel

Uzi Ram