Abstract: Various methods and apparatuses are disclosed, including a method for optimizing FEC code for an average number of interfering users in a multiple access communication, that includes receiving an FEC code optimization information, switchable between at least a first value and a second value, and selecting a first optimized FEC code based at least in part on the FEC code selection information being at the first value, and selecting a second optimized FEC code based at least in part on the FEC code selection information being at the second value. The method can include receiving a source bit stream, encoding bits of the source bit stream according to the selected optimized FEC code into a series of FEC encoded bits, and a parity check matrix of the first optimized FEC code has a first average information bit node degree, and a parity check matrix of the second optimized FEC code has a second average information bit node degree.

Abstract: A method for determining routes for a data circuit between source and destination terminals, where the circuit is formed via satellites traveling in respective non-geostationary orbits, and a total time during which the circuit is active is divided into time intervals. The determination of each route comprises, for each time interval, (i) selecting an uplink satellite to service the source terminal as an ingress node for the circuit, and (ii) determining a series of inter-satellite links connecting the uplink satellite to a downlink satellite servicing the destination terminal during the respective time interval, wherein the series of links is determined to be valid during the respective time interval. Each of the plurality of time intervals is of a duration based on a validity time, based on the satellites traveling in their respective orbits, for the inter-satellite link of all of the routes that is of the shortest duration.

Abstract: A method and system for providing high throughput communications via a Radio Frequency (RF) satellite are disclosed. The method includes providing a plurality of information bit streams intended for a plurality of downlinks; modulating an uplink stream including the plurality of information bit streams with an uplink modulation scheme to generate an uplink signal; transmitting the uplink signal to the satellite; and partitioning, at the satellite, the uplink signal into a plurality of downlink signals, each one intended for one of the plurality of downlinks. In the method, the uplink stream includes the plurality of information bit streams.

Abstract: A multiple access scheme is provided. A first communications terminal encodes a first data stream using a forward error correction (FEC) code, and scrambles the encoded first data stream based on a first scrambling signature. A second communications terminal encodes a second data stream using the FEC code, and scrambles the encoded second data stream based on a second scrambling signature. The first scrambling signature and the second scrambling signature are used, respectively, by the first terminal and the second terminal to distinguish the first encoded data stream from the second encoded data stream as respectively originating from the first terminal and the second terminal in a multiple access scheme, whereby the first encoded data stream and the second encoded data stream simultaneously share a wireless communications channel. The FEC code is a low density parity check (LDPC) code configured with a data node degree of two or three.

Abstract: Signal precoding can include: determining a first antenna pattern gain for a beam directed from a first antenna feed on the satellite toward a first user terminal in a first cell and determining a second antenna pattern gain for a beam directed from a second antenna feed on the satellite toward a second user terminal in a second cell adjacent to the first cell; wherein the adjacent cells are partitioned into sectors; determining a first sector location of the first user terminal and a second sector location of the second user terminal; a precoder matrix circuit using the determined first and second antenna pattern gains to calculate a precoder matrix to reduce interference levels caused by the first signal at the second sector and by the second signal at the first sector; and the precoder matrix circuit applying the precoder matrix to the first and second signals.

Abstract: Methods and apparatus for increasing spectral efficiency in non-orthogonal multiple access (NOMA) communication, that implement receiving a signal stream from a user, splitting the signal stream into a plurality of sub-streams, applying a forward error coding (FEC) to each one of the sub-streams, and outputting a corresponding plurality of FEC encoded sub-streams. This can include modulating a corresponding carrier with each of the FEC encoded sub-streams, and combining and transmitting the corresponding plurality of modulated carrier signals.

Abstract: Various methods and apparatuses are disclosed, including a method for optimizing FEC code for an average number of interfering users in a multiple access communication, that includes receiving an FEC code optimization information, switchable between at least a first value and a second value, and selecting a first optimized FEC code based at least in part on the FEC code selection information being at the first value, and selecting a second optimized FEC code based at least in part on the FEC code selection information being at the second value. The method can include receiving a source bit stream, encoding bits of the source bit stream according to the selected optimized FEC code into a series of FEC encoded bits, and a parity check matrix of the first optimized FEC code has a first average information bit node degree, and a parity check matrix of the second optimized FEC code has a second average information bit node degree.

Abstract: A multiple access scheme is described. A first bit stream is scrambled from a first terminal according to a first scrambling signature. A second bit stream is scrambled from a second terminal according to a second scrambling signature, wherein the first bit stream and the second bit stream are encoded using a low rate code. The first scrambling signature and the second scrambling signature are assigned, respectively, to the first terminal and the second terminal to provide a multiple access scheme.

Abstract: Interference cancellation in a receiver can be used to improve bandwidth efficiency. The transmission of bursts from different terminals scheduled at separate time intervals can overlap partially such that time used for information transmission is optimized. For example, a receiver includes a signal processor including instructions executable to select first data including a first burst and a successive second burst from a transmission. The signal processor demodulates and decodes information from the first burst. The signal processor further generates a remodulated first burst based on recoded and remodulated information and generates second data by subtracting the remodulated first burst from the first data. The signal processor synchronizes with a stored symbol pattern in the second burst; and demodulates and decodes the information from the second burst. With such arrangement, the performance of each link is not affected by the partially overlapping burst.

Abstract: A receiver, transmitter and system are programmed to communicate based on a signal including a plurality of signal components associated respectively with a plurality of subcarriers over a communications channel. The receiver is programmed to determine, from the plurality of subcarriers, a subcarrier subject to interference and erase the signal component associated with the subcarrier subject to interference. The receiver is further programmed to reconstruct the signal based on the plurality of first signal components excluding the erased first signal component.

Abstract: A transmitter, including a signal processor programmed to generate, based on input serial data, for each of an integer number of subcarriers mutually orthogonal to each other, a respective first parallel data stream. The signal processor is further programmed to modulate each of the integer number of subcarriers respectively with the respective parallel stream to generate the integer number of data-modulated subcarriers. The signal processor is further programmed to modulate a single carrier occupying a same bandwidth as the integer number of subcarriers with a unique word and one or more pilot symbols to generate a second signal. The signal processor combines the first signal and second signal to generate a third signal. The signal processor generates an output signal by applying a transmit filter to the third signal.

Abstract: A communications terminal comprises an encoder configured to encode a digital data signal to generate an encoded signal, a scrambler configured to scramble the encoded signal based on a scrambling signature, and a modulator configured to modulate resulting data frames for transmission via a random access communications channel. Each frame comprises a data payload, including a block of the scrambled signal, and a header, including a start of frame (SOF) sequence associated with the scrambling signature. Use of the SOF sequence for each frame provides a synchronization reference and serves to designate the associated scrambling signature for decoding the respective data payload. Use of the SOF sequence for each frame further serves to distinguish between the data frame and data frame(s) originating from further communications terminal(s), transmitted via a common time slot of the channel, for which different scrambling signature(s) were used to scramble respective encoded signal(s) thereof.

Abstract: An approach for increasing transmission throughput of a non-linear wireless channel, and efficient decoding of the transmitted signal via a simplified receiver, is provided. A signal reflects a source signal, and includes linear inter-symbol interference based on a faster-than-Nyquist signaling rate and a tight frequency roll-off, and non-linear interference based on high-power amplification for transmission over the wireless channel. The signal is received over a non-linear wireless channel, and is processed via a plurality of decoding iterations. A set of soft information of a current decoding iteration is generated based on a current estimate of the source signal and a final set of soft information from a previous decoding iteration. The current estimate of the source signal is based on an estimate of the linear ISI and the non-linear interference, which is based on the final set of soft information from the previous decoding iteration.

Abstract: A receiver, transmitter and system are programmed to communicate based on a signal including a plurality of signal components associated respectively with a plurality of subcarriers over a communications channel. The receiver is programmed to determine, from the plurality of subcarriers, a subcarrier subject to interference and erase the signal component associated with the subcarrier subject to interference. The receiver is further programmed to reconstruct the signal based on the plurality of first signal components excluding the erased first signal component.

Abstract: A method for determining routes for a data circuit between source and destination terminals, where the circuit is formed via satellites traveling in respective non-geostationary orbits, and a total time during which the circuit is active is divided into time intervals. The determination of each route comprises, for each time interval, (i) selecting an uplink satellite to service the source terminal as an ingress node for the circuit, and (ii) determining a series of inter-satellite links connecting the uplink satellite to a downlink satellite servicing the destination terminal during the respective time interval, wherein the series of links is determined to be valid during the respective time interval. Each of the plurality of time intervals is of a duration based on a validity time, based on the satellites traveling in their respective orbits, for the inter-satellite link of all of the routes that is of the shortest duration.

Abstract: A communications terminal receives a data communications signal via a random access channel. A processor searches for data bursts in a first time-slot that include one of a first set of signature sequences assigned to the first time-slot. When a data burst A in the first time-slot includes one of the first set of signature sequences, the data burst A in the first time-slot is an initial burst of a message from a first communications terminal. The processor determines whether a second time-slot includes a data burst B that includes the one signature sequence. When the second time-slot includes the data burst B, the message is a multi-burst message and that the data burst B is a second burst of the multi-burst message. When the second time-slot does not include the data burst B the message is a single-burst message that has been completed via the first time-slot.

Abstract: Methods and devices are provided. Devices asynchronously transmit, without diversity, bursts including information encoded using a low rate FEC code having a code rate no higher than ½. A terminal receives transmitted multiple overlapping bursts. The terminal detects and decodes bursts in a window of burst times, performs an iteration of an iterative interference cancellation process, and when at least one burst of at least a portion of the window remains incorrectly decoded, another iteration of the iterative cancellation process is performed as long as a maximum number of repeated iterations has not yet been performed. When all of the bursts in at least the portion of the window are correctly decoded, the window is advanced by an amount of burst time, at least the portion of the window is updated, and the iterations may be repeated. Correctly decoded bursts may be passed to a next process or device.

Abstract: An approach for increasing transmission throughput of a non-linear wireless channel, and efficient decoding of the transmitted signal via a simplified receiver, is provided. A signal reflects a source signal, and includes linear inter-symbol interference based on a faster-than-Nyquist signaling rate and a tight frequency roll-off, and non-linear interference based on high-power amplification for transmission over the wireless channel. The signal is received over a non-linear wireless channel, and is processed via a plurality of decoding iterations. A set of soft information of a current decoding iteration is generated based on a current estimate of the source signal and a final set of soft information from a previous decoding iteration. The current estimate of the source signal is based on an estimate of the linear ISI and the non-linear interference, which is based on the final set of soft information from the previous decoding iteration.

Abstract: A method and system for providing high throughput communications via a Radio Frequency (RF) satellite are disclosed. The method includes providing a plurality of information bit streams intended for a plurality of downlinks; modulating an uplink stream including the plurality of information bit streams with an uplink modulation scheme to generate an uplink signal; transmitting the uplink signal to the satellite; and partitioning, at the satellite, the uplink signal into a plurality of downlink signals, each one intended for one of the plurality of downlinks. In the method, the uplink stream includes the plurality of information bit streams.

Abstract: A high capacity communication system and method, and a high capacity communications configuration system are provided. The high capacity communication system includes a transmitter. The transmitter includes a signal generator to generate a signal including, wherein for a first frame portion extending from zero to ? time the signal is generated per a first color reuse plan of a frequency spectrum and one or more polarizations, and for a second frame portion extending from ? to T the signal is generated per a second color reuse plan of the frequency spectrum and the one or more polarizations; and an RF system to beam the signal concurrently to a first geographic area and a second geographic area.