SYSTEM AND METHOD FOR MANAGING MULTIPLE TRANSMISSION RESOURCES OF A SPATIAL MULTI-CELL RADIO-COMMUNICATION SYSTEM

• US 20130034050A1
• Filed: 08/03/2012
• Published: 02/07/2013
• Est. Priority Date: 08/04/2011
• Status: Active Grant

• Current Assignee: Centre National D'Etudes Spatiales
• Original Assignee: Centre National D'Etudes Spatiales
• Inventors: Ros, Benjamin, Boustie, Christelle, Scot, Gael
• Granted Patent: US 8,982,773 B2
• Time in Patent Office: Days
• US Class Current: 370/316
• CPC Class Codes: H04B 7/185 Space-based or airborne stations; Stations for satellite systemsH04B7/204 takes precedence
• CPC Class Codes: H04B 7/18528 Satellite systems for providing two-way communications service to a network of fixed stations, i.e. fixed satellite service or very small aperture terminal [VSAT] system
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management

Abstract

A satellite cellular radio-communication system using beam formation is provided. The system includes a satellite, at least one satellite access station, terminals, at least one control unit of a virtual cell. At least one of the terminals is configured to transmit and receive on a transmission channel having at least two frequency and spatial transmission resources of a same virtual cell that are different by their frequency band, a frequency and spatial transmission resource being a sub-band of a frequency band used in a beam. The frequency band is taken from among a predetermined number of frequency bands and was allocated to said beam according to a reuse function.

Claims

1. A satellite cellular radio-communication system comprising:

a transparent communication satellite serving as a relay, the transparent communication satellite in a geostationary orbit or a highly inclined elliptical orbit;

at least one satellite access station configured to transmit and receive service and signal messages to and from the satellite on a first bidirectional wireless way;

a set of user terminals configured to receive and transmit the service and signal messages from and to the satellite on a second bidirectional wireless way, the second bidirectional wireless way being made up of a second outbound downlink and a second inbound uplink; and

at least one control unit of a virtual cell, the at least one control unit being connected to one or more satellite access stations;

the communication satellite being configured to transmit on the second outbound downlink and to receive on the second inbound uplink the service and signal messages received and transmitted by the set of terminals, the service and signal messages being divided into a set of radio-communication satellite beams,

each satellite beam F(i) being identified by a first beam identification integer index i,

each satellite beam F(i) defining, by its wireless range on the ground, a satellite coverage of a satellite cell, and being associated with a frequency band taken among a predetermined number Nb of different frequency bands B(k), each frequency band B(k) being identified by a second band identification integer index k, with k varying from 1 to Nb,

each frequency band B(k) being subdivided into one or more frequency sub-bands SB(k, j), each sub-band being identified by a pair of indices (k, j), in which k is the index of the band and j is an integer comprised between 1, and an integer Nsb(j) depending on k,

the set of satellite beams being configured such that a band B(g(i)) allocated according to a distribution function g to any beam i is different from the bands associated with all of the beams adjacent to said any beam F(i), and

each satellite access station being associated with a different compact cluster of at least two satellite beams, no cluster taken among any two clusters having a shared beam,

a frequency and spatial transmission resource being a sub-band of index j of a band of index k assigned to a beam of index i and is associated with a triplet,

each virtual cell being a set of frequency and spatial transmission resources such that a set of beams of each virtual form a compact set of beams,

each terminal being associated with one virtual cell and being configured to receive, from the control unit of the associated virtual cell, and run a configuration command for a transmission channel to transmit and receive messages therein, the channel using at least two frequency and spatial resources at the same time having different band indices,

each control unit being configured to manage the frequency and spatial resources of the associated virtual cell associated therewith, and to make the messages received and transmitted by the terminals affected to the virtual cell of the control unit pass through.

2. The satellite cellular radio-communication system as recited claim 1 wherein each sub-band has a wide bandwidth greater than or equal to 2.5 MHz, and each terminal associated with the virtual cell is configured to measure the transmission quality of each sub-band of the virtual cell to which the virtual cell belongs at the same time.

3. The satellite cellular radio-communication system as recited claim 1 wherein the number of sub-bands per frequency band is constant, and the sub-bands of a same band have the same width.

4. The satellite cellular radio-communication system as recited claim 1 wherein each control unit includes a different reference clock and is configured to synchronize the messages transmitted and received by each terminal of the associated virtual cell on the reference clock of the associated virtual cell.

5. The satellite cellular radio-communication system as recited claim 1 wherein each satellite access station is configured to transmit and receive messages corresponding to the associated cluster, each satellite access station being connected to the one or more of the control units managing the frequency and spatial resources whereof the beam indices correspond to the beams of the cluster associated with the access station.

6. The satellite cellular radio-communication system as recited claim 1 wherein each satellite access station is served by at least two control units, at least one of the control units that serves the access station serving all of its frequency and spatial resources on the satellite access station.

7. The satellite cellular radio-communication system as recited claim 1 wherein each control unit serves at least two access stations.

8. The satellite cellular radio-communication system as recited claim 1 wherein each access station is served by one single control unit, and the one single control unit serves only that access station.

9. A method for changing transmission resources within a same virtual cell during a communication of a terminal in the system as recited in claim 1, comprising the following steps:

performing a wide band measurement of the transmission quality of each sub-band of the virtual cell with one of the terminals previously attached to the virtual cell, the terminal having a first list of frequency sub-bands used in the virtual cell;

sending, from the terminal to the control unit of the virtual cell, a first message containing information representative of the quality of each sub-band administered by the control unit of the virtual cell, through a first channel using one or more sub-bands of the virtual cell;

using the control unit to determine, from the quality information of the sub-bands of the current virtual cell and a second list of free channels of the virtual cell, the transmission parameters of a second channel comprising one or more sub-bands that corresponds to wireless reception conditions that are more favorable than those of the first channel, when such a second channel exists;

when a second channel exists, using the control unit to reserve the one or more sub-bands of the second channel and to prepare and send a second message to the terminal containing identification information of one or more reserved sub-bands of the second channel, and an order to switch from the first channel to the second channel;

after receiving and decoding the second message, using the terminal to execute the order to switch from the first channel to the second channel and sends the satellite any new message using the one or more reserved sub-bands of the second channel.

10. A method for changing transmission resources with switching from a first virtual cell to a second virtual cell during switching of a terminal in the system as recited in claim 1, comprising the following steps:

performing a wide band measurement of the transmission quality of each sub-band of the virtual cell with one of the terminals previously attached to the virtual cell, the terminal having a first list of frequency sub-bands used in the virtual cell;

sending, from the terminal to a first control unit of the first virtual cell, a first message containing information representative of the quality of each sub-band administered by the first control unit of the first virtual cell currently in force, through a first transmission channel currently using one or more sub-bands of the first virtual cell;

then, using the first control unit to determine, from quality information of the sub-bands of the current first virtual cell and a set of second lists of sub-bands of adjacent virtual cells in terms of beams, whether a second adjacent virtual cell exists in terms of beams capable of providing, for a long period, more favorable wireless reception conditions than those of any channel of the first virtual cell;

when such a second virtual cell exists, preparing, with a mobile switching center and a second control unit associated with the second virtual cell, a new high throughput connection on the high throughput network side, and sending, using the first control unit, the terminal a second message comprising an order to prepare a switch to a second transmission channel, identification information for the second virtual cell to which to switch, and a third list of sub-bands to scan of the second virtual cell to perform a wide band measurement of the set of channels offered by the second virtual cell;

after receiving the second message, sending, using the terminal, the second control unit, through a second transmission channel, a third message containing information representative of the quality of each sub-band administered by the second control unit of the second virtual cell;

determining, using the second control unit, from quality information of the sub-bands of the second virtual cell architecture, determined and supplied by the terminal, and a fourth list of free transmission channels of the second virtual cell, a third channel formed from one or more sub-bands comprised in the fourth list of free channels of the second virtual cell that corresponds to more favorable wireless reception conditions than those of the first channel;

using the second control unit to reserve the one or more sub-bands of the third channel and to prepare and send, on the second signal channel, a fourth message to the terminal containing identification information of the third channel and the one or more sub-bands allocated to the third channel;

using the terminal to receive and decode the fourth message, to store the information on the one or more sub-bands of the third channel reserved by the second control unit, and to send the first control unit a fifth announcement message that the terminal is ready to switch to the third channel of the second virtual cell;

after the first control unit receives the fifth message, using the first control unit to send an order to the mobile switching center to activate a second connection between the second control unit and the high throughput network, and to prepare and send the terminal a sixth message containing an order to switch to the second control unit of the second virtual cell and to use the third transmission channel; and

after the terminal receives and decodes the sixth message, using the terminal to execute the switching order from the first channel to the third channel and to send any new message on the second control unit.