WO2001013538A1 - Data retrieval method and apparatus in a mobile satellite communication system - Google Patents

Abstract

A method of retrieving data from a data store (82), comprising the steps of: transmitting from a mobile terminal (2) an outgoing radio message addressed to a data supply apparatus associated withthe data store (82); donwloading data from the data supply apparatus to a predetermined data receiver (66) in response to the outgoing radio message, the donwloaded data being relayed to the predetermined data receiver (66) by satellite link; characterised in that the outgoing radio message is transmitted over a non-circuit switched communication link.

Description

DATA RETRIEVAL METHOD AND APPARATUS IN A MOBILE SATELLITE COMMUNICATION SYSTEM

This invention relates to a data retrieval method and apparatus,

particularly but not exclusively a broad band radio data link for retrieving

5 information from a communications network such as the Internet.

Conventionally, users of the Internet and the World-wide Web use

dial-up modems in order to upload requests for files such as home pages,

documents or objects (hereinafter termed "files") and to receive the files

which are subsequently provided. However, current modems have data

0 transfer rates of only up to 56 kilobytes per second. Therefore, the

downloading of large data files is a time consuming operation.

Therefore, in recent years a great deal of research has gone into the

development of communication links, such as integrated services digital

network (ISDN) which are capable of transferring data at a higher rate in order

5 to reduce the times of transmission.

Another approach to reducing download transmission time is to

employ a satellite link between an Internet service provider (ISP) and the

recipient of the downloaded data. Examples of such systems are the Hughes

DirecPC™ System (developed by Hughes Network Systems Inc., a unit of

0 Hughes Electronics Corp. California US) and the Alcatel World Space™

System. In the case of DirecPC™, a user equipped with a personal computer

running suitable browser software, a DirecPC™ satellite dish, and a

connection to an ISP via a modem and public switched telephone network

(PSTN), or an ISDN link, may send a request for a file via the fixed line

network and receive the requested file by satellite transmission.

The user's request includes a "header", which is appended to the

request by the DirecPC™ software running on the user's personal computer.

The function of the header is to inform the Internet server to which the request

is directed that the source addressee, to which the requested file should be

directed, is a DirecPC™ Internet server, instead of the user in question. When

the DirecPC™ server receives the requested file, it is transmitted by radio to a

DirecPC™ satellite, which relays the transmission to the user's DirecPC™

satellite dish, connected to his personal computer.

As the outgoing request message is relatively small the narrow band

characteristics of the traditional modem and PSTN do not significantly

prolong the transmission time of the outgoing request. On the return path

however, a large quantity of data may need to be transmitted, depending upon

the size of the requested file. The return path consists of two types of

transmission. The first of these is between the server to which the request was

addressed and the DirecPC™ server, generally via a high capacity cable

connection. The second is between the DirecPC™ server and the user's

DirecPC™ dish, via broad band satellite transmission, capable of transmitting data at approximately 400 kilobytes per second. By avoiding narrow band

transmission media on the return path, when the volume of data to be

transmitted is often relatively large, it is ensured that the user receives the

requested files appreciably quicker than would otherwise be the case.

Clearly therefore systems like that of DirecPC™ rely on a standard

connection to a PSTN or ISDN in order to transmit the requested data; thus

preventing their use in areas not served by a terrestrial communications

infrastructure. Although it has been suggested that mobile phones may be

used in order to make a system such as DirecPC™ portable, this would result

in the inconvenience of monopolising the valuable resource of a mobile phone

during the potentially long periods in which the user wishes to browse the

Internet and thus maintain an Internet connection. In addition to this, the

relatively high call costs which are charged by some mobile phone operators

would make the such a use of a mobile phone costly and therefore unattractive

to the user.

According to the invention, there is provided a method of retrieving

data from a data store, comprising the steps of: transmitting from a mobile

terminal an outgoing radio message addressed to a data supply apparatus

associated with the data store; downloading data from the data supply

apparatus to a predetermined data receiver in response to the outgoing radio

message, the downloaded data being relayed to the predetermined data receiver by satellite link; characterised in that the outgoing radio message is

transmitted over a non-circuit switched communication link.

By providing a data retrieval method according to the present

invention, a user is able to take advantage of the possibility of being able to

retrieve data files from the Internet, wherever the mobile service to which the

user subscribes has coverage. However, in addition to this, the user need not

set up a standard two-way communications session using the mobile terminal.

He may instead use a short messaging service or a paging service, for

example. This gives rise to several advantages. Firstly, by transmitting the

request data by short message the mobile terminal remains free for use, to

make or receive calls. This of course would not be the case if a normal

switched circuit call were made to transmit the request data. Secondly, the

use of short message transmission is not dependent upon spare capacity in

terms of full circuit communication channels, which normally place the

greatest demands upon a mobile phone system, thus allowing the service

providers to improve service utilisation. Additionally, the cost to the user in

terms of utilisation of the mobile phone system resources may be reduced.

Preferably, the mobile terminal is a satellite terminal which has access

to a satellite communication network giving rise to extensive, preferably

global coverage.

Other aspects and embodiments of the invention, with corresponding

objects and advantages, will be apparent from the following description and claims. The invention will now be illustrated by way of example only with

reference to the accompany drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram showing schematically the elements of a

first communications system embodying the present invention;

Figure 2a is an illustrative is a block diagram showing schematically

the elements of mobile terminal equipment suitable for use with the present

invention; and

Figure 2b is a corresponding block diagram;

Figure 3 is a block diagram showing schematically the elements of an

Earth station node forming part of the embodiment of Figure 1;

Figure 4 illustrates schematically the beams produced by a satellite in

the embodiment of Figure 1 ;

Figure 5 illustrates schematically the disposition of satellites forming

part of Figure 1 in orbits around the Earth;

Figure 6 is a block diagram illustrating schematically the

interrelationship between the broad band satellite data link system and the

satellite mobile phone system of the described embodiment;

Figure 7 is a diagram showing schematically the spectral distribution

of frequency carriers on a user downlink beam;

Figure 8 is a diagram showing schematically the structure of a TDMA

frame on one of the carriers of Figure 6. SYSTEM HARDWARE

Satellite Mobile Communication System

The invention is envisaged for use with a satellite mobile digital

communications systems which has the capability of transmitting non-

switched transmissions such as short messages or datagrams from the user

terminal on a simplex channel. Various satellite based mobile voice

communications systems are known, however, an example of a suitable

satellite mobile voice communications system for implementing the present

invention is the ICO™ satellite cellular system (described in, for example,

GB-A-2295296).

Referring to Figure 1 , a satellite communications network according to

this embodiment comprises mobile user terminal equipment 2a, 2b (for

example handsets 2a and 2b); orbiting relay satellites 4a, 4b; satellite Earth

station nodes 6a, 6b; satellite system gateway stations 8a, 8b; terrestrial (for

example public switched) telecommunications networks 10a, 10b; and fixed

telecommunications terminal equipment 12a, 12b.

Interconnecting the satellite system gateways 8a, 8b with the Earth

station nodes 6a, 6b, and interconnecting the nodes 6a, 6b with each other, is a

dedicated ground-based network comprising channels 14a, 14b, 14c. The

satellites 4, Earth station nodes 6 and lines 14 make up the infrastructure of

the satellite communications network, for communication with the mobile

terminals 2, and accessible through the gateway stations 8. A terminal location database station 15 (equivalent to a GSM HLR) is

connected, via a signalling link 60 (for example within the channels 14 of the

dedicated network) to the gateway station and Earth stations 6.

The PSTNs 10a, 10b comprise, typically, local exchanges 16a, 16b to

which the fixed terminal equipment 12a, 12b is connected via local loops 18a,

18b; and international switching centres 20a, 20b connectable one to another

via transitional links 21 (for example, satellite links or subsea optical fibre

cable links). The PSTNs 10a, 10b and fixed terminal equipment 12a, 12b

(for example telephone instruments) are well known and almost universally

available today.

Although it is not germane to this invention, for voice

communications, each mobile terminal apparatus in a satellite a mobile phone

system such as is described in the ICO™ system (GB-A-2295296) is in

communication with a satellite 4 via a full duplex channel (in this

embodiment) comprising a downlink channel and an uplink channel, for

example (in each case) a TDMA time slot on a particular frequency allocated

on initiation of a call, as disclosed in UK patent applications GB 2288913

and GB 2293725. The satellites 4 in this embodiment are non geostationary,

and thus, periodically, there is handover from one satellite 4 to another.

Terminal 2

Referring to Figures 2a and 2b, a user terminal equipment 2 of Figure

1 is shown. The terminals 2a, 2b may be similar to those presently available for

use with the GSM system, comprising a digital low rate coder/decoder 30,

together with conventional microphone 36, loudspeaker 34, battery 40 and

keypad components 38, and a radio frequency (RF) interface 32 and antenna

31 suitable for satellite communications. A display 39 (for example a liquid

crystal display) and a 'smart card' reader 33 receiving a smart card (subscriber

identity module or SIM) 35 storing user information are also provided.

Specifically, the SIM 35 includes a processor 35a and permanent

memory 35b.

Also provided is a terminal control circuit 37 (which may in practice

be integrated with the coder 30) consisting of a suitably programmed

microprocessor, microcontroller or digital signal processor (DSP) chip.

The control circuit 37 performs various functions including framing

speech and data into TDMA time frames for transmission (and likewise

demultiplexing received TDMA frames); and performing encryption or

enciphering.

The coder/decoder (codec) 30 in this embodiment comprises a low bit

rate coder 30a, generating a speech bit stream at around 3.6 kilobits per

second, together with a channel coder 30b applying error correcting encoding,

to generate an encoded bit stream at a rate of 4.8 kilobits per second. The SIM memory 35b stores various subscriber identity data including

the international mobile subscriber identity (IMSI), which is a unique number

associated with that SIM (and hence the subscriber to whom it belongs).

Earth Station Node 6

The Earth station nodes 6 are arranged for communication with the

satellites.

Each Earth station node 6 comprises, as shown in Figure 3, a

conventional satellite Earth station 22 (functioning somewhat equivalently to

the Base Station of a cellular system) consisting of at least one satellite

tracking antenna 24 arranged to track at least one moving satellite 4, RF

power amplifiers 26a for supplying a signal to the antenna 24, and 26b for

receiving a signal from the antenna 24; and a control unit 28 for storing the

satellite ephemera data, controlling the steering of the antenna 24, and

effecting any control of the satellite 4 that may be required (by signalling via

the antenna 24 to the satellite 4).

The Earth station node 6 further comprises a mobile satellite switching

centre 42 comprising a network switch 44 connected to the trunk links 14

forming part of the dedicated network. It may be, for example, a

commercially available mobile switch centre (MSC) of the type used in digital

mobile cellular radio systems such as GSM systems. A multiplexer 46 is

arranged to receive switched calls from the switch 44 and multiplex them into

a composite signal for supply to the amplifier 26 via a low bit-rate voice codec 50. Finally, the Earth station node 6 comprises a local store 48 storing

details of each mobile terminal equipment 2 within the area served by the

satellite 4 with which the node 6 is in communication. The local store 48 acts

to fulfil the functions of a visited location register (VLR) of a GSM system,

and may be based on commercially available GSM products. Alternatively,

satellite control may be provided from a separate control station.

The gateway stations 8a, 8b comprise, in this embodiment,

commercially available mobile switch centres (MSCs) of the type used in

digital mobile cellular radio systems such as GSM systems. They could

alternatively comprise a part of an international or other exchange forming

one of the PSTNs 10a, 10b operating under software control to interconnect

the networks 10 with the satellite system trunk lines 14.

The gateway stations 8 comprise a switch arranged to interconnect

incoming PSTN lines from the PSTN 10 with dedicated service lines 14

connected to one or more Earth station nodes 6.

The gateway stations 8 also carry out the well known function of Short

Message Control Centres of a GSM system. That is to say that short

messages originating from mobile terminals 2 or short messages terminating

at mobile terminals 2 and originating elsewhere, for example the Internet, are

routed to a gateway station 8 prior to being delivered at their destination. As

is well known from the GSM system, the gateway stations 8 store short

messages which at that time can not be delivered for any reason. The delivery of such messages is subsequently reattempted. For the sake of clarity, when a

gateway station 8 is functioning in its short message capacity, it will hereafter

be referred to a short message control centre (SMSC).

The database station 15 comprises a digital data store which contains,

for every subscriber terminal apparatus 2, a record showing the identity (for

example the International Mobile Subscriber Identity or IMSI); and the

currently active Earth station node 6 with which the apparatus 2 is in

communication via the satellite 4.

Thus, in this embodiment the database station 15 acts to fulfil the

functions of a home location register (HLR) of a GSM system, and may be

based on commercially available GSM products.

Periodically, the Earth station nodes measure the delay and Doppler

shift of communications from the terminals 2 and transmit these to the

database station 15, which calculates the terrestrial position of the mobile

terminal apparatus 2 using the differential arrival times and or Doppler shifts

in the received signal, and knowledge of which beams of which satellites 4 the

signal was received through. The position is then stored in the database 48.

Satellites 4

The satellites 4a, 4b comprise generally conventional communications

satellite bus such as is used in the HS601 available from Hughes Aerospace

Corp, California, US, with a communications payload, which may be as

disclosed in GB 2288913. Each satellite 4 is arranged to generate an array (typically hexagonal) of beams each beam being generated by a separate

antenna, as described in EP 421722 A. The beams cover a footprint beneath

the satellite, each beam including a number of different frequency channels

and time slots, as described in GB 2293725 and illustrated in Figure 4.

On each beam, the satellite therefore transmits a set of user downlink

frequencies as shown in Figure 7. The frequencies are separated by a

frequency guard band. The downlink frequencies on adjacent beams are

different, so as to permit frequency re-use between beams. Each beam

therefore acts somewhat in the manner of a cell of a conventional terrestrial

cellular system. For example, there may be 163 beams. The frequencies are

allocated between satellites such that within each plane, neighbouring

satellites use different frequencies at those of their beams which overlap and

satellites from one plane use different frequencies than those used by satellites

of the other plane.

Similarly, each satellite is arranged to receive radiation in an array of

beams, which in this embodiment cover the same footprints beneath the

satellites, to provide a plurality of user uplink beams each carrying different

frequencies.

In this embodiment, referring to Figure 8, each uplink and downlink

frequency carries a plurality (for example 6) of time division channels, so that

each mobile terminal 2 communicates on a channel comprising a given time slot in a given uplink and downlink frequency. The time slots are separated by

a short guard interval.

Within each beam there is also provided a downlink common

broadcast control channel (equivalent to the broadcast common control

channel or BCCH of the GSM system) which occupies at least one of the

frequencies for each beam; the frequencies used by the broadcast control

channels of the beams are stored within each mobile terminal 2 which is

arranged to scan these frequencies.

The satellites of this embodiment function as repeaters. Each satellite

acts as a "bent pipe", amplifying and relaying signals from the user terminals

2 on the user terminal uplink, to the Earth station nodes 4 on a feeder

downlink. Also (although it is not germane to this invention) signals from the

Earth stations 4 on a feeder uplink are relayed down to the user terminals 2 on

a user downlink.

The satellites 4a are arranged in a constellation in sufficient numbers

and suitable orbits to cover a substantial area of the globe (preferably to give

global coverage).

For example 10 (or more) satellites may be provided in two mutually

orthogonal intermediate circular orbits (or more) at an altitude of, for

example, about 10,500 kilometres (6 hour orbits) and equatorial inclinations

of 45°, as shown in Figure 5. Equally, however, larger numbers of lower satellites may be used, as disclosed in EP 0365885, or other publications

relating to the Iridium system, for example.

Broadband Satellite Datalink System

Referring to Figure 6, the broadband satellite datalink hardware

consists of a personal computer (PC) 60 with a monitor a keyboard and a

mouse, with suitable Internet browser software loaded. The PC 60 is

connected via a communications port and connecting lead 64 to a satellite

receiver 66, in this case a very small aperture terminal (VSAT) comprising a

dish and RF circuits, which is arranged to be in the direct line of sight of a

broadband datalink system satellite 68 in order to receive its transmissions.

The PC 60 is also connected via a communications port and connecting lead

62 to a satellite mobile terminal 2 via its data port (described above), which is

similarly arranged to be in the direct line of sight of at least one of the

satellites 4 of the satellite mobile communication system (described above) in

order that it may transmit to that satellite 4.

The satellite datalink system also includes an Earth station 72 with an

associated radio transmitter 70, which is also arranged to be in direct line of

sight with the satellite 68. The Earth station 72 includes a satellite datalink

server 73 which is connected via terrestrial communication links 74a and 80

to the Internet 82 via an Internet Service Provider 78. The satellite datalink

server 73 is also connected to a database (not shown) containing the details of all subscribers to the system, including the geographic location of their

respective satellite receivers 66.

The satellite 68 is in this embodiment in a geostationary orbit, which

avoids the need for the satellite receiver 66 or the Earth station radio

transmitter 70 to track the movement of a non-geostationary satellite relative

to the Earth. As is described above, with reference to satellites 4a, 4b, the

satellite 68 acts as a one way repeater and comprises a generally conventional

communications satellite bus such as is used in the HS601 available from

Hughes Aerospace Corp, California, US with a communications payload, and

may be as disclosed in GB 2288913. It is arranged to generate an array

(typically hexagonal) of beams each beam being generated by a separate

antenna, as described in EP 421722A.

MODE OF OPERATION

Preparation of Short Message

Having made an Internet connection and launched the browser

software a user may download a file from the Internet, by identifying the file

in question so that it may be located by an Internet based server which is

charged with the task of relaying a copy of the file to the user. This is

conventionally achieved in one of three ways: Clicking on a hypertext link

with a mouse, for example; manually typing in a Universal Resource Locator

(URL), which defines the identity and location of the desired file, as is well

known in the art; or, selecting a URL from a list, which may be stored in the memory of the user's PC 60 as a "Favourite" Internet address found in the

graphical user interface (GUI) of the browser software. The location specifies

the Internet server through which the selected file is accessible.

In this example, the user selects the file which is to be downloaded

from the Internet (for example by selecting its title under the "Favourites"

heading of the GUI of the browser software). On doing this, the browser

software presents the corresponding URL.

The browser embeds the URL which was specified in an HTTP

request as is well know in the art. The HTTP request includes a standard

HTTP request line defining the function or "method" required of the target

server; in this case "GET", which requires the server to send a copy of the

requested file to the client. Additionally, the HTTP request includes a

standard HTTP "user-agent" header field, specifying the path by which the

target server should route the requested file. Normally, this would specify the

client browser (i.e. the network address of the PC 60). However, in the present

embodiment, this specifies the PC 60 at the server 73 of the satellite datalink

system; thus ensuring that the target server routes the requested file back to

the user via the server 73 and the satellite 68 as opposed to attempting to route

it via an ISP of the user and traditional modem connection, should one exist.

Thus the satellite datalink system server 73 will use this information to ensure

that the requested file is transmitted via the correct beam of the correct satellite 68 of the satellite datalink system for it to be correctly received by the

satellite receiver 66.

The browser software then adds additional routing data to the HTTP

request in order to form a short message ready for transmission. The routing

information defines the outward route of the short message by including the

directory number of the short message service centre 76 (SMSC) to which the

short message will be directed.

It will be appreciated by the skilled reader that the construction of the

short message is carried out by the browser in a manner that is transparent to

the user.

The user then initiates the message transmit function. As is

conventional, this is done by "clicking" an on screen "button" of the GUI of

the browser software using a mouse key. This causes the short message to be

output via the communications port of the PC 60 to the connected mobile

terminal 2. In this embodiment, once the short message has been downloaded

from the PC 60 to the mobile terminal 2, an appropriate man-machine

interface command is required to transmit the message from the mobile

terminal 2. Typically, the user must press the "send" button on the button pad

of the mobile terminal 2, as is the case for transmitting a short message

between mobile terminals in the GSM system. However, it will be

appreciated by the skilled reader that the mode of operation preferably allows

for the short message downloaded from the PC 60 to be self-sending by including appropriate signalling between the PC 60 and the mobile terminal 2

as is possible with software such as Nokia Smart Suite 2.

Short Message Transmission

The short messaging system of the present invention corresponds to

that of the GSM system which is in part defined in GSM Specification TS

GSM 09.02. The transmission of short messages is analogous to datagram

transmission in that, unlike circuit communication, no dedicated transmission

path is established since only signalling means are used. Furthermore, only

one process is used to the set up and end the communication, as well as

transmit the message.

In order to send a short message, the user terminal 2 sets up a

signalling connection with the Earth station node 6 via a satellite 4. Although

this may be done using a traffic channel whilst either in or not in full circuit

communication, specifically a Traffic Channel at Eighth rate (TCH/8) in the

GSM system, the Slow Associated Control Channel (SACCH), may instead

be used to transmit short messages. The signalling data is followed by the data

making up the short message. As the signalling data and the short message

data are transmitted together on the radio interface, service access point

identifiers (SAPI) are used to identify the two types. Each SAPI takes one of

two values to differentiate between signalling data and message data; for

example 0 to indicate signalling and 3 to indicate message data. The short message itself is transmitted in frames of fixed length

defined by the appropriate link protocol (LAPDm in this case). However,

messages of a length longer than that allowed for by one frame are sent over a

series of frames which are reconstructed on receipt by the Earth station node

6.

Routing of Short Message

The transmitted short message is received by a satellite 4 of the

satellite mobile phone system, which has a footprint overlying a portion of the

Earth's surface on which the user terminal 2 is located, provided that the

transmission path between the user terminal antenna and the satellite is not

blocked, for example, by buildings. On receipt of the short message by the

satellite 4, it is amplified and relayed to the Earth station node 6 of the

satellite communication system with which the satellite 4 is at that moment in

communication.

The Earth station node 6 routes the short message to the SMSC 76

defined by its directory number by terrestrial communication link 74b.

The SMSC 76 on recognising that the short message is in fact an

HTTP request, as opposed to a normal short message destined for another

mobile terminal, extracts and transmits the HTTP request alone to its ISP 78

via terrestrial communication link 74c.

The ISP 78 sends the HTTP request via terrestrial communication link

80 and Internet routers to the target Internet server specified by the URL, embedded in the HTTP request, in the conventional manner employed for

routing HTTP messages across the Internet.

Delivery of Requested File

The copying and delivery of the requested file from the target Internet

server via satellite 68 to the user's satellite receiver 66 is as is well known in

the art of broad band satellite data links. However, for the sake of clarity it

will be briefly described below. When the target Internet server receives the

HTTP request it responds, using well known conventional Internet protocols

and procedures, by obtaining the requested file. It then generates an HTTP

response, which includes an entity body containing an HTML file which the

user requested. Using the "user-agent" header field in the HTTP request and

with the aid of Internet routers, the HTTP response is sent via terrestrial

communication link 80 to the ISP 78, from where it is sent to the server 73 of

the satellite datalink system via terrestrial communication link 74a.

As the HTTP response is addressed to the user, the satellite datalink

system server 73 determines, through referring to systems databases (not

shown) which beam of the satellite 68 the file is required to be transmitted on

in order that it should be correctly received by the satellite receiver 66 of the

user. The file is then transmitted by Earth station transmitter 70 via satellite

68, to satellite receiver 66.

It will be understood by the skilled reader that many alternatives and

adaptations may be made to the above described embodiment. For example, although the above embodiment utilises a satellite based mobile

communications system, it will be apparent to the skilled reader that the

present invention can equally implemented using a terrestrial mobile

communications network, such as one conforming to the GSM standard.

Further functionality of the GSM system such as informing the user of

the successful delivery, or otherwise, of the short message to the SMSC, could

also be implemented to advantage in the present invention.

Although in the above embodiment URLs are used for identifying the

requested file, it will be apparent that other methods of identifying required

files may instead be used, for example through the use of forms.

Furthermore, the short message transmissions may be broadcast at a

higher power level than switched circuit communication. Thus, the request

message would be less likely to be subject to interference effects which could

otherwise corrupt the message.

Although the above embodiment uses a commercially available

broadband satellite communication system together with a separate

commercially available mobile phone network, it may alternatively be put into

practice with a complete purpose designed system.

However, it will be appreciated that satellites in a non-geostationary

orbit may also be used although in this case handover protocols will be

required.

Claims

1. A method of retrieving data from a data store, comprising the steps of:

transmitting from a mobile terminal an outgoing radio message

addressed to a data supply apparatus associated with the data store;

downloading data from the data supply apparatus to a predetermined

data receiver in response to the outgoing radio message, the downloaded data

being relayed to the predetermined data receiver by satellite link;

characterised in that the outgoing radio message is transmitted over a

non-circuit switched communication link.

2. A method according to claim 1, wherein the communication link is a

signalling, paging or messaging channel.

3. A method according to claim 2, wherein the channel is associated with

a circuit switched channel.

4. A method according to any preceding claim, wherein the outgoing

radio message is routed to the data supply apparatus via a satellite.

5. A method according to claim 4, wherein the satellite forms part of a

satellite mobile phone system.

6. A method according to claim 4 or 5, wherein the satellite is in a non-

geostationary orbit.

7. A method according to any one of claims 4 to 6, wherein the mobile

terminal is a satellite phone.

8. A method according to any one of claims 1 to 3, wherein the outgoing

radio message is routed to the data supply apparatus via a terrestrial cellular

phone system.

9. A method according to claim 8, wherein the mobile terminal is a

terrestrial cellular phone.

10. A method according to any preceding claim, wherein the mobile

terminal is arranged to communicate with an external data processor, the

external data processor being arranged to generate at least part of the outgoing

radio message and communicate it to the mobile terminal.

11. A method according to claim 10, wherein the external data processor is

a personal computer programmed with browser software.

12. A method according to claim 11, wherein the external data processor is

arranged to run browser software.

13. A method according to claim 10, 11 or 12, wherein the outgoing radio

message is transmitted under the control of the external data processor.

14. A method according to any preceding claim, wherein the predetermined

data receiver comprises a satellite receiver connected to the external data

processor.

15. A method according to any preceding claim, wherein the data store is

accessible via the Internet.

16. A method according to any preceding claim, wherein the data supply

apparatus is an Internet server.

17. An apparatus arranged to transmit an outgoing radio message over a

non-circuit switched communication link to a data supply apparatus

associated with a data store, the outgoing radio message being arranged to

cause said data supply apparatus to download data to a data receiver by

satellite link.

18. An apparatus according to claim 17, comprising a mobile phone.

19. An apparatus according to claim 17 or claim 18, wherein said mobile

phone is a satellite mobile phone.

20. An apparatus according to any one of claims 17 to 19, further

comprising a processor means connected to said mobile phone, said processor

means being arranged to generate at least part of said outgoing message.

21. An apparatus according to claim 20, wherein said processor means is a

personal computer.

22. A computer program comprising program code means for generating

the part of said outgoing message as defined in claim 10, when said program

is run on a computer.

23. A computer program according to claim 22, further comprising

program code means for communicating the part of said outgoing message to

a mobile terminal in communication with said computer and program code

means for controlling transmission of an outgoing message as defined in

claim 1 from said mobile terminal.

24. A computer program product comprising the program code means

defined in claim 21 or claim 22 stored on a computer readable medium.