Telecommunication system with increased channels by use of orbiting communication satellites

• US 5,455,961 A
• Filed: 04/01/1993
• Issued: 10/03/1995
• Est. Priority Date: 04/01/1992
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Nakagawa, Osamu
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): WISLER, MARK
• Application Number:
  US08/041,194
• Time in Patent Office: 915 Days
• Field of Search: 455/12.1, 455/13.1, 455/13.2, 455/62, 455/63, 455/67.6, 455/52.1, 342/357, 342/352, 342/358, 370/104.1
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/208 Frequency-division multiple access [FDMA]

Abstract

An orbiting satellite-based telecommunication system for providing store and forwarding service by having a ground station, in response to an instruction from an orbiting satellite over a specific communication channel of the down link, supply transmit data to the orbiting satellite through an unused one of a plurality of communication channels of the up link in accordance with a packet protocol, and having the ground station in response to another instruction from the orbiting satellite through the down link, receive the transmit data from the orbiting satellite through an unused one of said plurality of communication channels in accordance with the protocol wherein said orbiting satellite is provided with a divider for dividing the frequency band of the up link into a plurality of subchannels on the basis of the Doppler shift amount due to variations in the distance between a terminal and the orbiting satellite; a demodulator for demodulating the transmit data on a subchannel-by-subchannel basis; and data processor for processing said transmit data, demodulated on a subchannel-by-subchannel basis, by a predetermined procedure.

Claims

1. An orbiting satellite-based telecommunication system providing store and forwarding service and comprising an orbiting satellite and a plurality of ground stations and having respective down links from the orbiting satellite to the ground stations and respective up links from the ground stations to the orbiting satellite,

the orbiting satellite including:

a first transmitting means for transmitting down link data through one of the respective down links to a corresponding one of the ground stations;

a first receiving means for receiving up link data transmitted through one of the respective up links by the corresponding one of the ground stations;

dividing means connected to the first receiving means for dividing a frequency band of a communication channel of the one of the respective up links into a plurality of subchannels in accordance with a Doppler shift amount of frequency caused by a variation in distance between the corresponding one of the ground stations and the orbiting satellite; and

demodulation means connected to the dividing means for demodulating the up link data transmitted through the one of the respective up links from the corresponding one of the ground stations on a subchannel-by-subchannel basis; and

each of the ground stations including;

a second transmitting means for transmitting the up link data through the respective one of the up links; and

a second receiving means for receiving the down link data through the respective one of the down links, wherein

one of the ground stations transmits the up link data to the orbiting satellite through a respective one of the up links in response to a first instruction transmitted from the orbiting satellite through a respective one of the down links, and another of the ground stations receives the down link data from the orbiting satellite in response to a second instruction transmitted from the orbiting satellite through a respective another of the down links.

2. An orbiting satellite-based telecommunication system as recited in claim 1, wherein the orbiting satellite further includes processing means connected to the demodulation means for processing the transmit data transmitted from the one of the ground stations.

3. An orbiting satellite-based telecommunication system as recited in claim 1, wherein the subchannels are respectively associated with a plurality of areas which constitute different ground locations below a flight path of the orbiting satellite.

4. An orbiting satellite-based telecommunication system as recited in claim 1, wherein the each of the ground stations further includes:

a second dividing means connected to the second receiving means for dividing a frequency band of a communication channel of a respective one of the down links into one of a first subchannel for receiving a transmission permit signal at a first down link frequency and a second subchannel for receiving down link data at a second down link frequency, wherein the second down link frequency corresponds to a value obtained from the transmission permit signal.

5. An orbiting satellite-based telecommunication system as recited in claim 2, wherein the orbiting satellite further includes memory means connected to the processing means for storing and holding the transmit data transmitted from the one of the ground stations to transmit the transmit data to the another of the ground stations.

6. An orbiting satellite-based communication method for providing store and forwarding service between a plurality of ground stations through an orbiting satellite, each of the plurality of ground stations comprising transmitting means and receiving means, the orbiting satellite comprising transmitting means and receiving means, the receiving means of the orbiting satellite including means for dividing a frequency band of an up link communication channel from one of the ground stations to the orbiting satellite into a plurality of subchannels in accordance with a Doppler frequency shift amount caused by a change in distance between the one of the ground stations and the orbiting satellite, and demodulating means for demodulating data received from the one of the ground stations on a subchannel-by-subchannel basis, the method comprising the steps of:

transmitting a first instruction from the orbiting satellite to the one of the ground stations;

transmitting up link data from the one of the ground stations to the orbiting satellite in response to the first instruction;

receiving the up link data from the one of the ground stations through one of the subchannels in the orbiting satellite;

storing and holding the up link data in a memory in the orbiting satellite until the orbiting satellite comes into an orbital position to make a down link communication line with another of the ground stations;

transmitting a second instruction and the up link data held in the memory of the orbiting satellite to the another of the ground stations over the down link communication line; and

receiving the up link data held in the memory of the orbiting satellite in the another of the ground stations in accordance with the second instruction.

7. A satellite for providing store and forwarding service to a plurality of ground stations over respective down links from the satellite in orbit to the ground stations and over respective up links from the ground stations to the satellite in orbit, the satellite comprising:

transmitting means for transmitting down link data through one of the respective down links to a corresponding one of the ground stations;

receiving means for receiving up link data transmitted through one of the respective up links by the corresponding one of the ground stations;

dividing means connected to the receiving means for dividing a frequency band of a communication channel of one of the respective up links into a plurality of subchannels in accordance with a Doppler shift amount of frequency caused by a variation in distance between the respective one of the ground stations and the satellite in orbit;

demodulation means connected to the dividing means for demodulating the up link data transmitted through the one of the respective up links from the respective one of the ground stations on a subchannel-by-subchannel basis; and

a means for issuing a first and second instruction;

wherein one of the ground stations transmits the up link data to the satellite in orbit through a respective one of the up links in response to the first instruction transmitted from the satellite in orbit through a respective one of the down links, and another of the ground stations receives the down link data from the satellite in orbit in response to the second instruction transmitted from the satellite in orbit through a respective another of the down links.

8. A first ground station for receiving store and forwarding data from a second ground station via a satellite in orbit, the first and second ground stations sending up link signals to the satellite in orbit by respective up links, and the satellite in orbit sending down link signals to the first and second ground stations by respective down links, the first ground station comprising:

receiving means for receiving the down link signals at a radio frequency through the respective one of the down links from the satellite in orbit;

converting means connected to the receiving means for converting the frequency of the down link signals to an intermediate frequency;

demodulation means connected to the converting means for demodulating the down link signals at the intermediate frequency to down link data;

transmitting means for transmitting up link data through the respective one of the up links to the satellite in orbit, wherein

the first ground station transmits the up link data to the satellite in orbit through a respective one of the up links by the transmitting means of the first ground station in response to a first instruction transmitted from the satellite in orbit through a respective one of the down links, and the second ground station receives the down link data from the satellite in orbit by the receiving means of the second ground station in response to a second instruction transmitted from the orbiting satellite through a respective another of the down links, and wherein

the converting means converts a frequency band of a communication channel of the one of the respective up links into a plurality of subchannels in accordance with a Doppler shift amount of frequency caused by a variation in distance between the first and second ground stations and the satellite in orbit.