Abstract: A system and method for allocating one or more portions of the frequency spectrum among a plurality of radio frequency (RF) transmitters and/or receivers. The system comprises a hub station that dynamically allocates the frequency spectrum in response to demand of the plurality of RF transmitters and/or receivers. Based on the demand, the hub station analyzes the state of performance of one or more groups of RF transmitters and/or receivers, and optimizes utilization of the assigned frequency spectrum.

Abstract: An satellite-based internet access includes uses a distributed proxy server that reduces a delay associated with the retrieval of inline objects of web pages. The distributed proxy server includes a first component which runs on the browser side of the satellite link and communicates with web browsers, and a second component which runs on an Internet side of the satellite link and communicates with web servers. When a web page is requested over the satellite link, the second component determines whether the parent file includes any references to inline objects, and prefetches each such inline object. The prefetched objects are transmitted over the satellite link to the first component, which in-turn stores the prefetched objects in a cache and provides the prefetched objects to the requesting web browser. The first component may also block browser requests for prefetched inline objects from unnecessarily being transmitted over the satellite link.

Abstract: A communication system comprising three communication resources: a contention-type access block, a non-contention access block and a second non-contention access block called a reserved block. Each time that a remote unit has a block of data to transfer to a hub station, it sends the block of data over the contention-type access block. It also sends a corresponding notification message over the reserved block. If the hub station receives the notification message but not the block of data, it sends a response message to the remote unit which designates a resource within the non-contention access block. The remote unit then sends the block of data to the hub station over the designated resource.

Abstract: A method and apparatus related to a communication system in which a plurality of remote units encode data bursts using a predetermined codeword set and transmit the encoded data bursts to a hub station over a multiple-access channel. When the hub station receives a data burst from one of the remote units, the hub station demodulates the received data burst and correlates the received data burst with each codeword within the predetermined codeword set to determine which codeword has the maximum correlation. The hub station uses the correlation to derive a timing synchronization signal and/or a carrier frequency adjustment signal to be sent back to the remote unit. The signals provide information to the remote unit to synchronize its timing or adjust its carrier frequency for transmitting subsequent data bursts. The hub station may also use the correlation to estimate a signal-to-noise ratio.

Abstract: A communication system extracts a received modulation frequency from baseband modulation. This frequency is used as a reference to control the output of a variable oscillator. The output of the variable oscillator may be used to generate a transmit upconversion frequency, and may also be used to perform a downconversion from IF to baseband during receive operations.

Abstract: Time alignment of a signal from a remote unit at a hub station of a multiple access system is achieved based upon an initial time indication received from the hub station at the remote unit via a satellite. The remote unit transmits a signal to the satellite, monitors for a retransmission of the signal from the satellite and measures the time difference between the outgoing and incoming signals. The remote unit, then, uses the time difference to more finely adjust the time alignment. Alternatively, the remote unit transmits a first signal advanced with respect to an on-time estimate to the hub station and receives a responsive energy indication from the hub station. The remote unit transmits a second signal delayed with respect to the on-time estimate to the hub station and receives a responsive energy indication from the hub station. The remote unit compares the two energy indications and adjusts the on-time estimate.

Abstract: Transmission of TCP/IP data over a satellite link from a hub station to a plurality of remote units. The data, transmitted over the satellite link, uses the digital video broadcast (DVB) protocol. A field in the DVB header is used to indicate the location of the start of a new TCP/IP data packet within the DVB data. Use of a field in the DVB header to indicate the location of the start of a new TCP/IP data packet supports variable location of TCP/IP data within a DVB frame, and therefore more efficient use of the DVB bandwidth.

Abstract: Transmission of TCP/IP data over a satellite link from a hub station to a plurality of remote units. The data, transmitted over the satellite link, uses the digital video broadcast (DVB) protocol. A field in the DVB header is used to indicate the location of the start of a new TCP/IP data packet within the DVB data. Use of a field in the DVB header to indicate the location of the start of a new TCP/IP data packet supports variable location of TCP/IP data within a DVB frame, and therefore more efficient use of the DVB bandwidth.

Abstract: Transmission of TCP/IP data over a satellite link from a hub station to a plurality of remote units. The data, transmitted over the satellite link, uses the digital video broadcast (DVB) protocol. A field in the DVB header is used to indicate the location of the start of a new TCP/IP data packet within the DVB data. Use of a field in the DVB header to indicate the location of the start of a new TCP/IP data packet supports variable location of TCP/IP data within a DVB frame, and therefore more efficient use of the DVB bandwidth.

Abstract: A distributed proxy server is provided which reduces a delay associated with the retrieval of inline objects of web pages retrieved over a satellite link. The distributed proxy server includes a first component which runs on the browser side of the satellite link and communicates with web browsers, and a second component which runs on an Internet side of the satellite link and communicates with web servers. When a web page is requested over the satellite link and communicates with web servers. When a web page is requested over the satellite ink, the second component determines whether the parent file includes any references to inline objects, and prefetches each such inline object. The prefetched objects are transmitted over the satellite link to the first component, which in-turn stores the prefetched objets in a cache and provides the prefetched objects to the requesting web browser.

Abstract: In a system in which multiple remote units compete for limited communication resources, a remote unit accesses the system by randomly selecting a first sequence from a set of predetermined sequences. The remote unit transmits a data bit stream modulated with the first sequence beginning at one of a set of recurring admission boundaries. If the remote unit determines that the data bit stream has not been successfully received at a hub station, it randomly selects a second sequence from the set of predetermined sequences. The remote unit transmits the data bit stream modulated with the second sequence beginning at one of the set of recurring admission boundaries.

Abstract: A system and method is described for transmitting data from a remote unit to a hub station in order to transmit data across a wide area network, such as the Internet. The remote unit and the hub station have stored frequency tables that include the possible reverse link transmission frequencies. When a remote unit requests a frequency channel, the hub station broadcasts a message that includes the identifier of each remote unit that has requested a reverse link transmission channel. The list of identifiers from the hub station is in a specific order so that it can be stored into each remote unit's frequency table. Once the list of identifiers is stored, the remote unit can find its identifier's position within the frequency table to determine the frequency channel that was assigned by the hub station.

Abstract: A system for processing multiple channel buffers in a communication system using multiple processors in a hub station. One embodiment of the invention includes one or more remote units, a satellite in operable communication with the remote units, and a hub station in operable communication with the satellite. The hub station includes a plurality of channel buffers for storing data that is transmitted from the satellite and a plurality of processors. Each of the processors respectively processes in sequence each of the plurality of channel buffers, and each of the plurality of processors determines with respect to a currently selected channel whether the channel has a sufficient amount of databits to process. The determining step includes determining a current time, determining a previous point in time in which the databits have been processed, and determining whether the difference in time between the current time and the previous point in time is above a predefined threshold.

Abstract: In an internet access system which includes a satellite link, a distributed proxy server (68) is provided which reduces a delay associated with the retrieval of inline objects of web pages. The distributed proxy server (68) includes an access point component (70) and a satellite gateway component (72). The access point component (70) runs on the client (browser) side of the satellite link and communicates with web browsers (20A-20N). The satellite gateway component (72) runs on the internet side of the satellite link and communicates with web servers (26). As a web page is retrieved over the satellite link, the satellite gateway component (72) parses the base file component of the web page to identify any references to inline objects of the web page, and prefetches each such inline object.

Abstract: When an installed wireless remote unit is operating in the field, routine operation is interrupted to enter a calibration mode. In calibration mode, the compression point of a circuit element is determined by applying a series of different drive levels to the circuit element. Based upon the determination of the compression point, a maximum transmission point is selected for the remote unit. Upon resumption of normal operation, the remote unit uses the maximum transmission point to limit the signal power level transmitted over the wireless link. As time passes or operating conditions change, the calibration process is re-executed.

Abstract: A method and apparatus for digitally demodulating QPSK signals includes a first portion in which the digitally sampled data burst is resampled with a plurality of predetermined timing hypotheses. The timing offset is determined according to an analysis of the resampled data. The digitally sampled data burst is then resampled according to the timing estimation. Modulation of the resampled data burst is then removed by twice squaring the complex I/Q pairs. The data with the modulation removed is then subjected to a Chirp-Z Transform to move the data into the frequency domain. The highest spectral power is used to determine the frequency offset. The phase offset is determined and the resampled data burst is derotated and dephased according to the phase offset and the frequency offset.