Abstract: A method for efficient retransmission over a satellite network including transmitting data packets to VSATs, receiving retransmission requests for at least one of the data packets from the VSATs, generating a retransmission packet based on the retransmission requests using XOR summing, transmitting the retransmission packet to the plurality of VSATs.

Abstract: An approach is provided for increasing transmission throughput rates for a source signal transmitted over a wireless channel, applying faster-than-Nyquist (FTN) signaling rates combined with tight frequency roll-off to the a source signal. A receiver is provided that compensates for ISI effects induced by the FTN rate and tight frequency roll-off, where the complexity of the receiver grows only linearly with the interference memory. The receiver comprises an equalizer configured to compensate for the ISI effects, and a decoder configured to decode the output of the equalizer to determine and regenerate the source signal. The receiver processes the received signal via a plurality of processing iterations. For one processing iteration, the decoder generates a set of a posteriori soft information based on the output of the equalizer, and the equalizer uses the a posteriori soft information as a priori soft information for a subsequent processing iteration.

Abstract: A signal transmission approach comprises encoding a source signal (comprising a plurality of source symbols) to generate a corresponding encoded signal. The encoded signal is modulated by mapping each source symbol to a respective signal constellation point of an applied signal constellation to generate a modulated signal. The modulated signal is pre-distorted based on a distortion estimate to generate a pre-distorted signal. The pre-distorted signal is filtered to generate a filtered signal. The filtered signal is frequency translated and amplified to generate a transmission signal for transmission via an uplink channel of a satellite communications system. To increase throughput, the source signal is processed through the apparatus and the resulting transmission signal is generated at a Faster-than-Nyquist (FTN) symbol rate and with a tight frequency roll-off.

Abstract: Approaches are provided for closing communications channel links (e.g., for small terminal applications in satellite communications systems), at lower effective data rates, in a most power efficient manner, while still meeting regulatory requirements. Such approaches employ modulation and coding schemes that facilitate such lower effective data rates in a most power efficient manner. The new modulation and coding schemes include new low density parity check (LDPC) codes.

Abstract: Method and apparatus for implementing LDPC codes in an IEEE 802.11 standard system configured to operate in a Multiple-Input, Multiple-Output (MIMO) schema. A method in accordance with the present invention comprises defining a base LDPC code, having a length equal to an integer number of data carriers in an ODFM symbol, transmitting the base LDPC code over a plurality of sub-carriers, wherein the base code is transmitted at an expected phase on sub-carriers specified by the IEEE 802.11 standard system, and transmitting the base LDPC code on other sub-carriers than those specified by the IEEE 802.11 standard system, wherein the base LDPC code on the other sub-carriers is transmit offset in phase from the base LDPC code on the specified sub-carriers.

Abstract: An approach for encoding a physical layer (PL) header of a PL data frame is provided. The PL header comprises sixteen information bits ui, (i=0, 1, 2, . . . , 15), and the encoding is based on a convolutional code, whereby, for each information bit, five associated parity bits Pi,k, (k=0, 1, 2, 3, 4) are generated, resulting in 80 codebits. The resulting 80 codebits are punctured to form a (16,77) codeword (c0, c1, c2, c76). The codebits of the (16,77) codeword are repeated to generate a (16,154) physical layer signaling codeword (c0, c0, c1, c1, c2, c2, c76, c76) for transmission of the PL data frame over a channel of a communications network.

Abstract: A physical layer (PL) frame generation method is provided. A PL payload is generated by encoding and modulating source data based on a first modcod of a first set. A synchronization header, comprising a first unique word (UW) (designed to facilitate efficient and reliable detection by terminals of a relatively low SNR operating range), and a modcod field (which indicates the first modcod scheme), is appended to the PL payload. A PL header is appended to the synchronization header and PL payload to form the PL frame. The PL header comprises a second UW and physical layer signaling (PLS). The PLS comprises encoded data fields reflecting a length of the PL frame, where the fields are encoded based on a second modcod scheme of a second set. The first modcod set is designed for SNR operating levels relatively lower than the SNR operating levels of the second modcod set.

Abstract: A method for efficient retransmission over a satellite network including transmitting data packets to VSATs, receiving retransmission requests for at least one of the data packets from the VSATs, generating a retransmission packet based on the retransmission requests using XOR summing, transmitting the retransmission packet to the plurality of VSATs.

Abstract: The present invention provides an approach for FEC encoding based on intermediate code block lengths not associated with any supported mother FEC code. A first string of k2 data bits is received. The first string of data bits is encoded to generate an N2 bit code block for transmission over a channel of a wireless communications network. The first data bit string is encoded based on a supported (N1,k1) forward error correction (FEC) code of a code rate R=k1/N1, configured to encode a string of data bits of a length k1 bits to generate a code block of a length N1 bits. To facilitate the encoding of the first string of data bits based on the (N1,k1) FEC code, the encoding comprises padding, repeating and/or puncturing the first string of data bits and a resulting N1 bit code block to generate the N2 bit code block.

Abstract: Approaches for satellite data transmissions are provided, which accommodate for periodic signal blockages without packet loss. A data stream is segmented into packets for wireless transmission, wherein the transmission is subject to a periodic blockage, wherein the periodic blockage comprises two blockages occurring within a time period, and each blockage is of a respective duration and recurs at regular intervals based on the time period. A forward error correction outer code is applied to the packets for recovery of data erasures due to the periodic blockage, wherein the application of the outer code comprises applying an error correction code to each of the packets to generate a respective codeblock. Each codeblock is interleaved to prevent erasure of consecutive parity bits within the codeblock. The encoded and interleaved codeblocks are transmitted over a wireless channel, wherein a number of data erasures occur within each codeblock due to the periodic blockage.

Abstract: An approach for encoding a physical layer (PL) header of a PL data frame is provided. The PL header comprises sixteen information bits ui, (i=0, 1, 2, . . . , 15), and the encoding is based on a convolutional code, whereby, for each information bit, five associated parity bits pi,k, (k=0, 1, 2, 3, 4) are generated, resulting in 80 codebits. The resulting 80 codebits are punctured to form a (16,77) codeword (c0, c1, c2, . . . , c76). The codebits of the (16,77) codeword are repeated to generate a (16,154) physical layer signaling codeword (c0, c0, c1, c1, c2, c2, . . . , c76, c76) for transmission of the PL data frame over a channel of a communications network.

Abstract: The present invention provides an approach for FEC encoding based on intermediate code block lengths not associated with any supported mother FEC code. A first string of k2 data bits is received. The first string of data bits is encoded to generate an N2 bit code block for transmission over a channel of a wireless communications network. The first data bit string is encoded based on a supported (N1, k1) forward error correction (FEC) code of a code rate R=k1/N1, configured to encode a string of data bits of a length k1 bits to generate a code block of a length N1 bits. To facilitate the encoding of the first string of data bits based on the (N1, k1) FEC code, the encoding comprises padding, repeating and/or puncturing the first string of data bits and a resulting N1 bit code block to generate the N2 bit code block.

Abstract: A physical layer (PL) frame generation method is provided. A PL payload is generated by encoding and modulating source data based on a first modcod of a first set. A synchronization header, comprising a first unique word (UW) (designed to facilitate efficient and reliable detection by terminals of a relatively low SNR operating range), and a modcod field (which indicates the first modcod scheme), is appended to the PL payload. A PL header is appended to the synchronization header and PL payload to form the PL frame. The PL header comprises a second UW and physical layer signaling (PLS). The PLS comprises encoded data fields reflecting a length of the PL frame, where the fields are encoded based on a second modcod scheme of a second set. The first modcod set is designed for SNR operating levels relatively lower than the SNR operating levels of the second modcod set.

Abstract: A system and method for data transmissions in a wireless communications system, which accommodates for a periodic blockage of the transmission signal, is provided. A data stream is segmented into packets of a predetermined fixed-size for a burst-mode transmission over a channel of the communications system, wherein the transmission is subject to a periodic blockage. A forward error correction outer code is then applied to the packets of the data stream for recovery of packets subjected to the periodic blockage, and a unique word is added to each packet for acquisition of frequency, carrier phase and symbol timing of the respective packet. The packets of the data stream are interleaved based on an interleaver of a depth based at least in part on a ratio of a blockage free duration between two consecutive blockages of the periodic blockage to a duration of each blockage of the periodic blockage.

Abstract: A signal transmission approach comprises encoding a source signal (comprising a plurality of source symbols) to generate a corresponding encoded signal. The encoded signal is modulated by mapping each source symbol to a respective signal constellation point of an applied signal constellation to generate a modulated signal. The modulated signal is pre-distorted based on a distortion estimate to generate a pre-distorted signal. The pre-distorted signal is filtered to generate a filtered signal. The filtered signal is frequency translated and amplified to generate a transmission signal for transmission via an uplink channel of a satellite communications system. To increase throughput, the source signal is processed through the apparatus and the resulting transmission signal is generated at a Faster-than-Nyquist (FTN) symbol rate and with a tight frequency roll-off.

Abstract: The present invention provides a low density parity check (LDPC) code system and method of using such a system. A transmitted LDPC code block size may be chosen such that the minimum transmitted block size is minimized. Further, the system provides for intermediate LDPC code block size support. Finally, a common decoder architecture may be used to decode different LDPC code rates and block sizes.

Abstract: An approach is provided for an improved coding approach for efficient header signaling in broadband communications networks, to provide support of expanded modulation and coding scheme sets that facilitate an expansion of the operational ranges of user terminals within such networks and finer granularity within such operational ranges. A mode indicator field of a frame header identifies a modulation/coding mode applied to a data payload of the data frame. The modulation/coding mode is one of either a first or second set of modulation/coding modes. The mode indicator field is encoded and modulated. When the modulation/coding mode is one of the first set, the modulation of the encoded mode indicator field is applied in a first mode, and when the modulation/coding mode is one of the second set, the modulation of the encoded mode indicator field is applied in a second mode.

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 physical layer (PL) frame generation method is provided. A PL payload is generated by encoding and modulating source data based on a first modcod of a first set. A synchronization header (a unique word (UW) of a UW set) is appended to the PL payload. The UWs of the set respectively correspond to different modcods of the first set, and the UW corresponds to the first modcod. A PL header is appended to the synchronization header and PL payload to form the PL frame. The PL header comprises a second UW and physical layer signaling (PLS). The PLS comprises encoded data fields reflecting a length of the PL frame, where the data fields are encoded based on a second modcod scheme of a second set. The first modcod set is designed for an SNR operating range relatively lower than the SNR operating range of the second modcod set.

Abstract: A new coded continuous phase modulation (CPM) scheme is proposed to enhance physical layer performance of the current DVB-RCS standard for a satellite communication system. The proposed CPM scheme uses a phase pulse design and combination of modulation parameters to shape the power spectrum of CPM signal in order to improve resilience to adjacent channel interference (ACI). Additionally, it uses a low complexity binary convolutional codes and S-random bit interleaving. Phase response using the proposed CPM scheme is a weighted average of the conventional rectangular and raised-cosine responses and provides optimum response to minimize frame error rate for a given data rate.