1. Satellite Communications Alison Griffiths – Room C203, Beacon Building a.l.griffiths@staffs.ac.uk

2. MCCS What we will look at What we will look at What are satellite phones What are satellite phones How do they operate How do they operate How do they integrate into the PSTN network How do they integrate into the PSTN network Who operates this phone network Who operates this phone network

3. MCCS Over the next few weeks we will look at mobile telecommunications Over the next few weeks we will look at mobile telecommunications 2G, 2.5G, 3G, 4G 2G, 2.5G, 3G, 4G These are all designed to operate within a proximity of a transmitter / receiver (base stations) These are all designed to operate within a proximity of a transmitter / receiver (base stations) Now consider what happens in areas where there are no base stations Now consider what happens in areas where there are no base stations This could be for financial reasons, as in there is just not enough use to justify the base station This could be for financial reasons, as in there is just not enough use to justify the base station Practical reasons as in it is impossible to install a base station, like the middle of the Pacific ocean Practical reasons as in it is impossible to install a base station, like the middle of the Pacific ocean For these users an alternative needs to be offered For these users an alternative needs to be offered For a lot of people it unacceptable to be disconnected from the world for long periods of time For a lot of people it unacceptable to be disconnected from the world for long periods of time This is becoming increasingly true in the wired world This is becoming increasingly true in the wired world

4. MCCS Areas where cellular communications are not possible Satellite phones are an option Areas where cellular communications are not possible Satellite phones are an option Original theorised by Arthur C. Clarke in 1945 Original theorised by Arthur C. Clarke in 1945 Paper called “Extra Terrestrial Rays” Paper called “Extra Terrestrial Rays” A number of private sector businesses are investing in this infrastructure A number of private sector businesses are investing in this infrastructure They are hoping to gain access to the large majority of the world who do not have access to Mobile telecommunications They are hoping to gain access to the large majority of the world who do not have access to Mobile telecommunications They also want to gain the travelling business people They also want to gain the travelling business people Although as we will discuss over the new few weeks any standard of telecommunications after 2G are supposed to be compatible outside of the host country there are still problems in reality Although as we will discuss over the new few weeks any standard of telecommunications after 2G are supposed to be compatible outside of the host country there are still problems in reality Local roaming agreements are needed with each of the countries which are not always in place Local roaming agreements are needed with each of the countries which are not always in place Different countries use different technologies Different countries use different technologies

5. MCCS - Companies Only a few companies control the worldwide satellite market Only a few companies control the worldwide satellite market Some of them are listed below Some of them are listed below Iridium Iridium Globalstar Globalstar ICO ICO Ellipse Ellipse Asian Cellular System (ACES) Asian Cellular System (ACES) Thuraya Thuraya Teledesic Teledesic

6. MCCS - Companies There are three kinds of satellite used for these communications There are three kinds of satellite used for these communications LEO LEO Low Earth Orbit Low Earth Orbit 350 to 1400 Km above the Earth 350 to 1400 Km above the Earth MEO MEO Medium Earth Orbit Medium Earth Orbit 6,000 to 20,000 Km above the Earth 6,000 to 20,000 Km above the Earth Global Positioning System is a user of these satellites Global Positioning System is a user of these satellites GEO GEO Geostationary Earth Orbit Geostationary Earth Orbit 36,000 Km above the equator 36,000 Km above the equator

7. MCCS - Satellites GEOMEO LEO

8. MCCS - Companies The closer the satellite is to the Earth the less area is covered by each one The closer the satellite is to the Earth the less area is covered by each one GEO orbit GEO orbit A minimum 3 satellites are needed to cover the planet A minimum 3 satellites are needed to cover the planet The satellite will remain in one location rotating with the Earth The satellite will remain in one location rotating with the Earth The company ACES uses this technology The company ACES uses this technology ACES actually only uses 1 satellite as they only offer services over Asia, not globally ACES actually only uses 1 satellite as they only offer services over Asia, not globally Relatively a Large amount of power is needed to transmit Relatively a Large amount of power is needed to transmit LEO LEO A large number of satellites are needed to cover the planet A large number of satellites are needed to cover the planet Iridium, uses 66 satellites for global coverage + spares in case of problems Iridium, uses 66 satellites for global coverage + spares in case of problems

9. MCCS – GEO Using a GEO satellite Using a GEO satellite Means that if 2 people wish to communicate in the same area a ground station is not required Means that if 2 people wish to communicate in the same area a ground station is not required The signal can be received and transferred back to the recipient The signal can be received and transferred back to the recipient Due to the distance involved with GEO Due to the distance involved with GEO Delay may occur within the call Delay may occur within the call About 260 ms delay in what is said before it can be returned to the other party. About 260 ms delay in what is said before it can be returned to the other party. If both parties in the call are on satellite phones this will get longer and more noticeable If both parties in the call are on satellite phones this will get longer and more noticeable Person 1 Person 2

10. MCCS – Connecting Using a LEO satellite Using a LEO satellite These satellites are closer to Earth These satellites are closer to Earth Each one will cover a small area Each one will cover a small area Referred to as the “footprint” Referred to as the “footprint” This has large advantages in the respect frequencies can be reused in different parts of the planet at the same time This has large advantages in the respect frequencies can be reused in different parts of the planet at the same time This is the same basis that cellular communications operate upon This is the same basis that cellular communications operate upon Due to the distance to satellite Due to the distance to satellite The latency issue is less of a concern average 10 ms The latency issue is less of a concern average 10 ms This is similar delay as you would get on any land base PSTN This is similar delay as you would get on any land base PSTN Less power is required to transmit to the satellite Less power is required to transmit to the satellite

11. MCCS – Connecting Two types of satellites exist for LEO designs Two types of satellites exist for LEO designs Repeaters (also known as “bent pipe”) Repeaters (also known as “bent pipe”) These just receive a signal and forward it to a ground station to be routed to the destination These just receive a signal and forward it to a ground station to be routed to the destination Very simple operation and rely on the fact that a ground station is within transmission distance Very simple operation and rely on the fact that a ground station is within transmission distance This is seen in the following diagram This is seen in the following diagram

12. MCCS – LEO - Repeater Person 1 Person 2

13. MCCS – Connecting Two types of satellites exist for LEO designs Two types of satellites exist for LEO designs Routers Routers These operate like a router in a computer network These operate like a router in a computer network The destination of a packet is inspected The destination of a packet is inspected This allows inter satellite handover or call routing This allows inter satellite handover or call routing The removal of the transmission to the ground station removes a potential problem for the network. The removal of the transmission to the ground station removes a potential problem for the network. Ground stations only need to be informed at the end for call charging purposes Ground stations only need to be informed at the end for call charging purposes

14. MCCS – LEO - Router Person 1 Person 2

15. MCCS – Connecting The way that each of the methods communicate varies with each of the companies The way that each of the methods communicate varies with each of the companies The satellites use a variety of standards to allow communication with the handsets The satellites use a variety of standards to allow communication with the handsets TDMA/FDMA and CDMA are predominant technologies TDMA/FDMA and CDMA are predominant technologies These will both be covered in a later lecture These will both be covered in a later lecture Each of the companies are issued with a range of radio frequency Each of the companies are issued with a range of radio frequency These are reserved and offered by the ITU These are reserved and offered by the ITU International Telecommunications Union International Telecommunications Union More about this organisation will be discussed in the GSM lectures More about this organisation will be discussed in the GSM lectures

16. MCCS – Frequencies Operating frequencies Operating frequencies A number of frequencies are issued A number of frequencies are issued Each of these frequency ranges are issued a letter to designate the frequency and the potential use Each of these frequency ranges are issued a letter to designate the frequency and the potential use The use depends on the intention of the satellite The use depends on the intention of the satellite C 4 GHz – 6 GHz 4 GHz – 6 GHz L 390 MHz – 1.55 GHz 390 MHz – 1.55 GHz GPS System GPS System Iridium Iridium K u K u 12 – 18 GHz 12 – 18 GHz K a K a 18 – 40 GHz 18 – 40 GHz X 5.2GHz – 10.9 GHz 5.2GHz – 10.9 GHz V 50 GHz – 75 GHz 50 GHz – 75 GHz

17. MCCS – Connecting Ground stations Ground stations Depending on the technology affects the number of ground stations Depending on the technology affects the number of ground stations Operations Operations Link satellites into the PSTN Link satellites into the PSTN Send/receive control signals Send/receive control signals Control billing / access information Control billing / access information PSTN

18. MCCS – Connecting Communications needed Communications needed Communicate with another satellite phone Communicate with another satellite phone Communication with another satellite phone in a different position Communication with another satellite phone in a different position Communications with phone attached to the PSTN Communications with phone attached to the PSTN This will include Mobile phones as these will be routed through the PSTN This will include Mobile phones as these will be routed through the PSTN

19. MCCS – Connecting Technologies used for LEO with Inter satellite handover Technologies used for LEO with Inter satellite handover Mean that it is POSSIBLE to hand only one ground station for all calls being handled Mean that it is POSSIBLE to hand only one ground station for all calls being handled This would however mean This would however mean A single point of failure within the network A single point of failure within the network Routing PSTN calls further than required Routing PSTN calls further than required Increased inter satellite communications Increased inter satellite communications In the event of a single satellite failing all worldwide communications could be effected In the event of a single satellite failing all worldwide communications could be effected Using multiple ground stations allows for Using multiple ground stations allows for More control More control Redundancy in the network Redundancy in the network Reduced cost of connecting to the PSTN Reduced cost of connecting to the PSTN

20. MCCS – Connecting Single Ground station Single Ground station Someone in China phoning a PSTN in China Someone in China phoning a PSTN in China China Canada PSTN

21. MCCS – Connecting Multiple Ground stations Multiple Ground stations Someone in China phoning a PSTN in China Someone in China phoning a PSTN in China China PSTN

22. MCCS Satellite phones Satellite phones Need a clear line of sight to operate properly Need a clear line of sight to operate properly The line of sight is towards the satellite The line of sight is towards the satellite This is usually towards the horizon, where the best opportunity is available to receive a satellite signal This is usually towards the horizon, where the best opportunity is available to receive a satellite signal

23. MCCS - Handsets Current generation if handsets look like cellular phones Current generation if handsets look like cellular phones An aerial must be used to get the best signal An aerial must be used to get the best signal Voice quality is not as good as the GSM network Voice quality is not as good as the GSM network The phones are slightly bulkier than the new slim line GSM devices The phones are slightly bulkier than the new slim line GSM devices Battery life is lower than GSM devices Battery life is lower than GSM devices There are multiple standard at the moment for phones There are multiple standard at the moment for phones Devices which work with one satellite group may not work with another Devices which work with one satellite group may not work with another http://www.highspeedsat.com/motorola-9505.htm http://www.highspeedsat.com/motorola-9505.htm http://www.highspeedsat.com/motorola-9505.htm

24. MCCS - Future Future use of Satellite based phones will be seen Future use of Satellite based phones will be seen Most of the current companies are having financial problems Most of the current companies are having financial problems Iridium went bankrupt and was bought out in 1999/2000 Iridium went bankrupt and was bought out in 1999/2000 Other companies are scaling down planned growth of the systems Other companies are scaling down planned growth of the systems The IMT-2000 specifications for 3G communications does include a discussion on Satellite phones to make them compatible with cellular handsets The IMT-2000 specifications for 3G communications does include a discussion on Satellite phones to make them compatible with cellular handsets The intention is to attempt to allow a “standard” 3G compliant phone operate anywhere The intention is to attempt to allow a “standard” 3G compliant phone operate anywhere

25. MCCS - Future IMT-2000 Vision http://cis270.williamson.cx/3G.2/imt_2000_Concept_imsi.gif

26. MCCS - Future IMT-2000 IMT-2000 Looking at using Satellite phones for areas where cellular communications will not be possible Looking at using Satellite phones for areas where cellular communications will not be possible These phones will offer increased voice quality and data rates These phones will offer increased voice quality and data rates 144 Kbps actual rates will define once operators start to use this technology 144 Kbps actual rates will define once operators start to use this technology Current Data Rates are about 8Kbps for satellite phones Current Data Rates are about 8Kbps for satellite phones Different sorts of Satellite communications can be used for high speed data transfer in the region of 2 to 45 Mbps Different sorts of Satellite communications can be used for high speed data transfer in the region of 2 to 45 Mbps New technology starting 2005 is Icomera, which is providing wireless LAN access via satellite to trains in Europe New technology starting 2005 is Icomera, which is providing wireless LAN access via satellite to trains in Europe http://www.icomera.com/default.asp http://www.icomera.com/default.asp

27. MCCS Conclusion Conclusion Looked at satellite technology Looked at satellite technology Different types of satellites Different types of satellites Considerations Considerations Future of satellite phone technology Future of satellite phone technology