Abstract: A device is provided for use with a satellite and a receiver having a local oscillator. The satellite is traveling in a vector and transmits a signal having an expected frequency. The receiver receives a received signal having a received signal frequency. The device includes: a Doppler shift measuring portion measuring a Doppler shift Dm; a predetermined Doppler shift storage portion storing a predetermined received Doppler shift Dp; a received signal Doppler shift error calculating portion calculating a received signal Doppler shift error De; a predetermined receiver position storage portion storing a predetermined position Pp of the receiver; and a receiver position estimating portion calculating an estimated receiver position Pe based on the predetermined position Pp of the receiver and the received signal Doppler shift error De.

Abstract: Aspects of the invention provide a system and method to allow inroute frame timing synchronization without the aid of hub signal loopback or satellite ephemeris data. Furthermore, it allows tracking and compensating of the satellite motion to allow multiple remotes to use TDMA on the inroute frequencies, while minimizing the aperture. Two main techniques proposed are CLT and polling based approaches, which are used in combination for an optimum solution. In CLT based approach, hub transmits remote specific timing correction feedback messages on the outroute on as needed basis. In polling based approach, the remotes derive their timing based on a per-beam average delay estimate broadcast by the hub and a measured local delay specific to each outroute stream from a remote. An aspect of the invention uses triangulation method to determine satellite position. Furthermore, an aspect of the invention uses hub burst arrival method instead of polling approach.

Abstract: A high capacity satellite communications system including a satellite with a beam for a forward downlink focused on a geographic area for which disproportionately higher capacity is desired, a hub located in a geographic area for which disproportionately lower capacity is desired, compared to the location of a VSAT, and the VSAT located in area where a beam for a forward downlink received by the VSAT from the satellite does not overlap with a beam for a return downlink received by the hub from a satellite.

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: An apparatus includes a receiver component, a first signal processing component and a second signal processing component. The receiver component can receive a transmission signal, wherein the received transmission signal reflects an encoded and modulated initial source signal, amplified via a source transmitter, and transmitted over one or more channels of a wireless communications network. The first signal processing component can process the received transmission signal to generate a replica transmission signal that estimates the encoded and modulated initial source signal. The second signal processing component can determine an optimal parametric function for modeling the source transmitter, wherein the determination of the optimal parametric function comprises an iterative non-linear curve-fitting process, and wherein the optimal parametric function reflects one or more parameters of the source transmitter.

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 high penetration alerting in a mobile satellite system. A message is generated for transmission to a wireless terminal. The message is partitioned into a number of symbols, each symbol composed of a portion of the message. The symbols are encoded via FEC coding to generate outer coded symbols, and each outer coded symbol is encoded based on a corresponding binary orthogonal sequence. The inner coded symbols are modulated based on a binary modulation scheme, and pulse shaped to generate message bursts for transmission to the wireless terminal. Each message burst reflects a group of the inner coded symbols, wherein the grouping of the inner coded symbols facilitates joint sequence detection by the wireless terminal, and each message burst exhibits relatively low peak-to-average power ratio.

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: An apparatus for satellite selection within a multi-satellite communication system, comprising an antenna, receiver, and transmitter, and a processing module configured to calculate a normalized distance metric for the plurality of user spot beams of a first and second satellite, select the user spot beam with the lowest normalized distance metric, and determine which of the at least first or second satellite is transmitting the selected user spot beam. Further, a method for increasing the aggregate capacity of a satellite communications network, comprising identifying high traffic regions within a coverage area of a first satellite, determining which user spot beams of the first satellite are available to each of the identified regions, determining a normalized distance metric for each user spot beam identified, and plotting a second beam pattern of a second satellite to produce at least one user spot beam with a lower normalized distance metric.

Abstract: An approach includes injecting a plurality of equal amplitude tones across a frequency band. The approach also includes determining frequency response based on the injected tones, determining an imbalance parameter associated with a quadrature down-converter based on the determined frequency response; determining one or more parameters for wideband quadrature compensation based on the determined frequency response, and compensating an input signal based on the determined imbalance parameter and the determined one or more parameters for the wideband quadrature compensation.

Abstract: A method for iterative estimation of a set of unknown channel parameters in a beamforming network including determining a first order estimate of offsets at measurement nodes and an estimate of the confidence in the initial estimate of the measurement nodes' offsets, and iterating, until a desired estimation accuracy is obtained, determining an improved estimate of a parameter set, and the confidence in the estimates, using the prior estimate of the offsets at the measurement nodes and determining an improved estimate of the offsets at the measurement nodes and the associated confidence values using the prior estimate of the parameter set and the corresponding confidence values.

Abstract: An apparatus for PLL bandwidth expansion including a compensation filter and a phase locked loop, where the compensation filter is programmed with a compensation function derived based on programmable coefficients and parameters of a transmitting device, a frequency response of the phase locked loop, and a wanted frequency response.

Abstract: Various approaches are introduced to provide link adaptation to maximize the resource utilization of the satellite network: (i) a method to adapt the transmission rate for packet voice and data traffics; (ii) a method to control the transmit power of packet voice and data channels; and (iii) a method to accomplish the feedback loop in a secured and correct manner.

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: Approaches for resource efficient multicast communications in mobile satellite systems are provided. A wireless gateway is configured to encapsulate multicast signaling messages received from participating remote terminals. The encapsulation is compatible with the core network of the system, whereby the signaling is passed through the core network undetected. The signaling is received by a multicast gateway, and provides necessary IP and port addressing information for the multicast gateway to encapsulate the multicast session data in a manner compatible with the core network. Upon receiving multicast session data from a multicast server, the multicast gateway replicates and encapsulates each data packet with IP and port addressing for each participating remote terminal, which is also passed through the core network undetected.

Abstract: Methods and apparatus for performing dynamic load balancing across transmission channels in a communications system, for loads of multiple priorities for a plurality of terminals are provided. Priority levels for a plurality of traffic flows from the plurality of terminals are determined, and the traffic flows are assigned to a plurality of transmission channels to load balance the traffic flows based on the determined priority levels. The load balancing includes generating a load vector for each of the transmission channels, and determining a load balancing target for the load vectors. The load balancing further includes determining a centroid point for the generated load vectors, wherein the centroid point is the load balancing target, and iteratively converging to the centroid point as the load balancing target by determining cancellation pairs for the load vectors, to balance loads of multiple priorities.

Abstract: An apparatus for beam selection for a multibeam satellite communications system including a very small aperture terminal (VSAT) with a remote satellite dish for sending and receiving RF signals and processor for calculating a normalized distance metric for user spot beams, selecting the user spot beam with the lowest normalized distance metric, and finding an outroute on the selected user spot beam using the remote satellite dish.

Abstract: A transmission and reception spot beam antenna is provided. A first transponder is configured to receive communications signals within a first receive spot beam and to transmit the communications signals within a first transmit spot beam. A second transponder is configured to receive reach-back signals within a second receive spot beam and to process the reach-back signals. A link between the second transponder and the first transponder passes the reach-back signals to the first transponder for transmission within the first transmit spot beam. A third transponder is configured to receive communications signals within a third receive spot beam and to transmit the communications signals within a third transmit spot beam. A link between the first transponder and the third transponder passes the communications signals to the third transponder, wherein the third transponder is configured to process the communications signals for transmission within the third transmit spot beam.

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: An approach for providing secure communication services is disclosed. A secure (e.g., a Virtual Private Network (VPN)) tunnel from a source node over an access network, such as a satellite network, to a destination node, wherein the nodes are external to the network. A connection that supports a mechanism for enhancing performance of the network is established for a portion of the secure tunnel that traverses the network.