Abstract:
An improved satellite communication system is provided comprising at least one satellite wherein each satellite provides multiple beams, a plurality of UTs, and at least one gateway connected to a PSTN and communicating with said at least one UT or with a constellation, wherein each of the UTs within a given frequency band is distinguished from another of the UTs employing a combination of TDM and NOPN codes and time slots.
Abstract:
There is provided a method for improving an allocation of resources, i.e., frequency and power, to terrestrial services and satellite services that use a same frequency band. The method includes determining a demand (DS) for a resource by users of a satellite system, determining a demand (DT) for the resource by users of a terrestrial system, and allocating the resource between the satellite system and the terrestrial system based on a ratio of DS to DT.
Abstract:
Disclosed are systems, apparatus and methods for tracking or locating an asset along with providing emergency and non-emergency messaging services. An asset tracker is disposed on an asset. The asset tracker has a motion sensor, a GPS receiver and a simplex satellite transmitter for communicating with a remote location (back office processing center). The asset tracker also has a short-range transceiver for communicating with a fob device carried by a user. If an authorized fob device is not in range of the asset tracker device and the asset tracker device moves, as determined by the motion sensor and/or GPS location data, GPS data are transmitted via a satellite to the back office. The office sends the information to a desired recipient (asset owner, law enforcement, etc.). The fob device communicates with the asset tracker device when it is in proximity thereof. The fob device is programmed to have depressible buttons that transmit emergency and non-emergency messages to the asset tracker device which communicates the GPS location and message via a satellite to the back office. The back office sends the information to a desired recipient. Messages processed at the processing center are sent as email messages to one or more designated email addresses, as a short message service (SMS) messages to one or more designated cell phones, or as messages to an asset recovery service or 911 emergency center.
Abstract:
A communications system comprising a first transceiver and a second transceiver, which system employs a device that measures power over a frequency band from sources other than those monitoring downlink radiation received at a radio terminal from the satellite, and a controller that receives these power measurements to determine on which frequency channel within a band a transmitter is to transmit.
Abstract:
Disclosed herein is a method for operating a satellite communications system as well as a method for providing a larger effective gateway coverage area, and a system that operates in accordance with the methods. The methods include steps of (a) establishing a call connection between a terrestrial telecommunications network and a user terminal via a first gateway and at least one satellite; and (b) while the call connection is established, coupling the user terminal to the terrestrial telecommunications network via a second gateway and at least one further satellite. The step of coupling includes a step of conveying call speech or data information between the first gateway and the second gateway over an inter-gateway communications link. By so linking multiple gateways each gateway experiences an increase in its effective coverage area, as an on-going call can be continued even after a user terminal moves from a first gateway's coverage area into a second gateway's coverage area.
Abstract:
The satellite communication system comprises a plurality of satellites. The frequency bandwidth of the return link to each satellite is subdivided into a plurality of channels. The method includes steps of finding a total interference in each channel, calculating a predicted total interference from addition of a first user terminal to each channel, determining if the predicted total interference is a minimum, and allocating the first channel to the first user terminal. The predicted total interference is calculated for each channel of the plurality of channels in the return link to each of at least two satellites. The first channel is allocated to the first user terminal if the predicted total interference in the first channel is the minimum value.
Abstract:
A system and method for controlling the transmission power of a user terminal in a satellite communications system of a type that includes a ground segment, comprised of at least one user terminal and at least one terrestrial gateway, and a space segment, comprised of a plurality of satellites in a non-geosynchronous earth orbit. The method includes the steps of (a) transmitting an uplink signal from the user terminal simultaneously to at least two satellites of the space segment and (b) receiving the uplink signal with each of the at least two satellites. The method further includes the steps of (c) determining, in the space segment, a difference value representing a difference between a received signal strength indication and a desired received signal strength indication for each of the at least two satellites; (d) in response to the difference value, generating in the space segment at least one power control command for use by the user terminal; (e) transmitting the at least one generated power control command from the space segment to the user terminal; and (f) adjusting a transmitted power of the uplink signal in accordance with the at least one power control command.
Abstract:
A method and system wherein a system gateway (18) determines, from closed loop power control information, a power density at an antenna (13a) of a user terminal 13. The gateway also maintains a record of a duration of time that the power density exceeds a specified threshold. The gateway determines if an averaged transmitted power density associated with the antenna of the user terminal will equal or exceed at least one of a predetermined threshold level, within a specified period of time, or an absolute threshold level. If the gateway determines that a threshold will probably be exceeded if the call connection is maintained, the gateway terminates the connection prior to a time that the user terminal averaged transmitted power density level equals or exceeds the predetermined or absolute threshold level. A tone or a visual indicator may be employed to warn the user that a current connection or call will be terminated. Provisions are made for allowing predetermined types of calls (e.g., emergency calls) to be made during a cutoff period wherein the user terminal is prohibited from placing further calls. It within the scope of the invention to perform the power density monitoring function also within the user terminal. In this case information may be transferred to the GW over a return link, and majority voting or some other technique can be employed by the GW before terminating the connection. In this case the power density determination made at the GW has priority over that made in the user terminal to prevent a user terminal from intentionally or inadvertently defeating the power density monitoring function.
Abstract:
A communication system (10), and a method executed by same, for allocating communications traffic through a plurality of satellites (12) of a constellation of low earth orbit satellites. Each of the plurality of satellites is oriented, at any given time when in view of a ground station (18), at a particular elevation angle. The method comprises the steps of: (a) providing each of the plurality of satellites with a receiver for receiving communication links from the ground station and a transmitter for transmitting communication links to user terminals; (b) in response to a request for service, determining if a highest elevation angle satellite can be assigned a new communications link; (c) if yes, assigning a new communication link to the highest elevation angle satellite; (d) if no, determining if a second highest elevation angle satellite can be assigned a new communications link; and (e) if yes, assigning a new communication link to the second highest elevation angle satellite. A number of different criteria can be employed in determining if a satellite can be assigned a new communication link, including: determining if the associated satellite has already been assigned a predetermined maximum number of communication links; and determining if the associated satellite, or a particular beam, is transmitting at or near to a power level that corresponds to a maximum peak flux density at the surface of the earth. Each of the steps of assigning is preferably accomplished such that the communication link is simultaneously established through at least two of the satellites to provide for diversity reception at a user's terminal (13).
Abstract:
A interface device and a method of allowing communication is provided to allow a wireless mobile communications device to interface with a satellite communication system. The interface includes a satellite modem (including antenna), a communications link to communicate with the wireless communications device (such as a Wifi link using VoIP) and an applications processor (with associated memory) to handle control and handshaking functions between the communications link and satellite modem and the related interfaced equipment (mobile communications device and satellite system) and to assist and reformat as needed transmission of data between the interfaced equipment.