Abstract: A communication system having a proxy architecture is disclosed. The system includes a platform that provides performance enhancing functions. The platform includes a path selection/activation apparatus that routes information within a communication system. The path selection/activation apparatus receives path selection and path activation parameters from the platform and maintains the current parameters in one or more path selection/activation profiles. The path selection/activation apparatus routes packets of information throughout the communication system based on the path selection and/or path activation profile. The above arrangement has particular applicability to a bandwidth constrained communication system, such as a satellite network.

Abstract: A system for managing return channel bandwidth in a two-way satellite communication network is disclosed. A plurality of transceivers transmit backlog information over a return channel via a satellite, wherein the backlog information specify an amount of queued traffic for the respective transceivers. A hub receives the backlog information and allocates a minimal amount of return channel bandwidth to each of the transceivers. The hub selectively sets a bandwidth level associated with the return channel bandwidth that is available based upon one of a plurality of predetermined bandwidth levels according to a predetermined criteria. The hub selectively allocates additional return channel bandwidth based upon the bandwidth level to the transceivers that require additional return channel bandwidth in excess of the allocated minimal amounts.

Abstract: An approach for allocating bandwidth in a satellite communication system is disclosed. The system includes a set of global queues that store bandwidth requests, which are received from a number of satellite terminals. The received bandwidth request include a high priority rate request, a low priority rate request, a high priority volume request, and a low priority volume request. A bandwidth control processor determines bandwidth request type and priority of the received bandwidth requests and places the bandwidth requests in the appropriate global queues based upon the determined bandwidth request type and priority. Each of the global queues corresponds to a data rate associated with of each a plurality of channels. The system also utilizes a set of local queues that correspond to the channels. The BCP moves the bandwidth requests from the global queues to the local queues. The BCP then allocates the transmission slots in response to the bandwidth requests stored in the local queues.

Abstract: Two types of contention channels are used to accommodate broadband packet data in a satellite communication network. A first contention channel is used by unsynchronized user terminals to access the system and request a traffic channel. The first contention channel is of a sufficient duration to accommodate a RACH message, as well as the timing uncertainty between user terminals within a given spot beam. A second contention channel is shorter in duration than the first contention channel, and is narrowband, so that more than one second contention channel may be transmitted within the bandwidth of the broadband traffic channels. The second contention channels are used by synchronized user terminals for transmitting packet RACH, or PRACH, messages. The more efficient nature of the PRACH channels accommodates the increased overhead associated with bursty packet data, without the capacity cost of the longer duration RACH channel.

Abstract: A vector modulator including an offset QPSK modulator operative for receiving input data and generating a first output signal representing the modulation to be imposed on a carrier signal to effect offset QPSK modulation of the input signal and a second output signal representing an amplitude of the input data; and a frequency modulator including a sigma-delta modulator, operative for receiving the first output signal generated by the offset QPSK modulator, and generating a control signal representing the desired frequency of the carrier signal such that the carrier signal represents the input signal offset QPSK modulated.

Abstract: A method and apparatus for enhancing the performance of a network by performing selective spoofing. Selective spoofing provides the ability to discriminate among different connections and only allocate spoofing resources to those connections for which spoofing will actually improve performance. The selective spoofing functions described are applicable to a wide variety of communication links, including both slow and fast links, high latency links, and links with low and high error rates. The selective spoofing functions may be implemented either alone or in combination with other performance enhancing features, such as, spoofing the conventional TCP three-way handshake, local data acknowledgement, multiplexing multiple connections across a single connection, data compression/encryption, prioritization, and path selection. The selective spoofing features described are particularly useful for links with high latency and/or high bit error rates.

Abstract: An apparatus for transmitting and receiving signals over a two-way satellite communication system is disclosed. A receiving unit receives data from a user terminal. A transmitting unit is coupled to the receiving unit and transmits the data to an antenna. The data is transmitted over a return channel that is established over the satellite to a hub; the hub has connectivity to a packet switched network.

Abstract: A method, system, and software product for transmitting TTY/TDD signals in a system employing low bit-rate voice compression are disclosed. The method includes receiving an input signal and generating a teletypewriter (TTY) indicator signal from the input signal. Whether or not the input signal is a TTY signal including a TTY character, is determined based on the TTY indicator signal. A TTY packet including the TTY character of the TTY signal is constructed and transmitted if the input signal is determined to be a TTY signal. A method, system, and software product for receiving and decoding TTY/TDD signal is also disclosed.

Abstract: An approach for transmitting packets conforming with the TCP (Transmission Control Protocol) over a satellite communications network comprises a plurality of prioritized queues that are configured to store the packets. The packets conform with a predetermined protocol. A classification logic classifies the packets based upon the predetermined protocol. The packet is selectively stored in one of the plurality of queues, wherein the one queue is of a relatively high priority. The packet is scheduled for transmission over the satellite communications network according to the relative priority of the one queue.

Abstract: A method of pointing an antenna at a transmitter comprising the steps of: (a) varying the azimuth of the antenna dish a predetermined number of degrees in a first direction from a predetermined azimuth angle; (b) measuring a first signal strength of an incoming signal received by the antenna dish; (c) varying the azimuth of the antenna dish the same predetermined number of degrees in a second direction from the predetermined azimuth angle, where the second direction is opposite to the first direction; (d) measuring a second signal strength of the incoming signal received by the antenna dish; and (e) comparing the first signal strength to the second signal strength, and if the first signal strength substantially equals the second signal strength, the current predetermined azimuth angle represents the optimal angle of azimuth for the antenna dish.

Abstract: An approach for controlling bandwidth allocations for a switching system with transmission constraints is disclosed. A scheduler within a switching system generates bandwidth metrics for a destination site. A traffic control processing logic receives the bandwidth metrics. The traffic control processing logic includes a utilization module that determines utilization associated with the destination site based upon the received bandwidth metrics, and an error calculation module that computes the difference between the determined utilization and a target utilization. A gain and filtering module, which is also a part of the traffic control processing logic, computes a correction value based upon the difference between the determined utilization and the target utilization, in which the correction value being associated with the destination site. Further, the traffic control processing logic includes an adder that outputs a control value based upon a reference control value and the correction value.

Abstract: A sigma delta interpolator for use in a fractional N synthesizer having a multi-modulus divider for controlling the output frequency of the synthesizer. The sigma delta interpolator includes an accumulator operative for receiving an input signal representing the desired frequency output of the fractional N synthesizer and for generating a digital output signal having M bits, which include N most significant bits and n least significant bits. The N most significant bits output by the accumulator are coupled to the multi-modulus divider and are operative for controlling the operation of the multi-modulus divider. The sigma delta interpolator further includes a delay circuit coupled to the accumulator, which functions to receive the n least significant bits and implement a delay function defined by equation: 1?(1?Z?1)N, where N corresponds to the order of the sigma delta interpolator.

Abstract: An approach for allocating system capacity of a communication switching system for exchange of traffic is disclosed. The system includes multiple terminals that request allocations of system capacity. The capacity is partitioned into a provisioned portion and an unprovisioned portion, in which a portion of the terminals constitutes a pool having a plurality of sub-pools. According to one embodiment, a control computer communicates with the plurality of terminals and allocates the provisioned portion of the capacity to the plurality of sub-pools of the terminals. The provisioned portion of the capacity is arranged into sub-partitions, wherein one of the sub-partitions is not associated with the sub-pools of terminals. Remaining sub-partitions are associated with the sub-pools of terminals.

Abstract: An apparatus for providing automatic gain control for use in a satellite terminal of a satellite communication system capable of transmitting a plurality of different modes of data. The apparatus includes a demodulator circuit having an analog to digital converter; a first variable attenuator having an attenuation value set on the basis of a measured power level of a predetermined data signal; and a second variable attenuator having an attenuation value set on the basis of the mode of data being received by the satellite terminal, where each of the data modes have a corresponding predetermined attenuation value associated therewith which is utilized as the attenuation value of the second variable attenuator when the satellite terminal receives the data mode.