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Introduction
Satellite Internet and 5G

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Physical media: radio
Radio link types:
Satellite Radio Channels
typically for areas without DSL or cable-based internet access
Communication satellite links to microwave transmitter/receiver ground station(s)
Satellite receives transmission signals on onefrequency band, regenerates the signal, then transmits the signal using another frequency.
Introduction 1-2

https://getgravity.nz/satellite-internet/introduction/
Geostationary satellites (in orbit at 36,000km above)
280 msec propagation delay
15 Mbps to hundreds of Mbps
Low altitude (Low-Earth-Orbiting satellites) – may be used for future Internet access.Multiple satellites are placed in orbit that communicate with each other and other ground stations, to provide continuous coverage to an area.

Terrestrialmicrowave

Microwaves are widely used for point-to-point communications because their small wavelength allows conveniently-sized antennas to direct them in narrow beams, which can be pointed directly at the receiving antenna

– advantage: Satellite Broadband lets you access the internet from virtually anywhere, even without a phone line, as long as there’s a clear line of sight to the satellite.
– advantage: allows nearby microwave equipment to use the same frequencies without interfering with each other, as lower frequency radio waves do.

advantage: high frequency of microwaves gives the microwave band a very large information-carrying capacity; the microwave band has a bandwidth 30 times that of all the rest of the radio spectrum below it.

Disadvantage: microwaves are limited to line of sight propagation; they cannot pass around hills, mountains, buildings, trees as lower frequency radio waves can.

//geostationary satellites
// – placed in orbit, around 36,000 km above the Earth’s surface
– one that could orbit the Earth above the equator and remain fixed by following the Earth’s rotation

A geostationary satellite is an earth-orbiting satellite, placed at an altitude of approximately 35,800 kilometers (22,300 miles) directly over the equator, that revolves in the same direction the earth rotates (west to east). – It can offer high data speeds, with newer satellites achieving downstream data speeds up to 15 Mbps.

Physical media: radio
Carry signals in the ultra high frequency band (300MHz to 3GHz) of the electromagnetic spectrum
Wavelength = up to 1dm
can penetrate walls
no physical “wire”
bidirectional
Propagation is affected by environment:
Signal reflection off interfering objects
Interference due to other transmissions
Radio link types:
TerrestrialRadio Channels
Local area radio channels: LAN (e.g., WiFi)
11Mbps, 54 Mbps
Wide-area radio channels (e.g., cellular)
3G cellular: ~ 1 Mbps, 4G LTE:>10 Mbps

Introduction 1-3
https://en.wikipedia.org/wiki/Electromagnetic_spectrum

https://en.wikipedia.org/wiki/Ultra_high_frequency

1G: first cellphones
2G: let us texting on the cellphone for the first time
3G: brought us on-line using cellphone
4G: delivered fast internet connection on the cellphone (but it has already reached the limit to support more devices; connecting more devices in the future could cause slower service, more dropped connections)
5G: could support a thousand more traffic than today’s network, 10x – 100x faster than 4G LTE
5G could serve as the foundation for virtual reality, autonomous driving, internet of things

5G: Higher data rate, fast response time
5G networks have the major advantage of achieving much higher data rates than previous cellular networks, up to 10 Gbit/s; which is faster than current cable internet, and 100 times faster than the previous cellular technology, 4G LTE.
Can download an HD movie in under a second.It can add capacity for millions more devices.

4G: under 50msec. response time
5G: below 1 msec. response time (400 times faster than a blink of an eye)

Foundation Technologies for 5G

1. Millimeter waves
Radio waves are a type of electromagnetic radiation with wavelengths longer than infrared light.Radio waves have frequencies between 30Hz to 300 GHz.At 300 GHz the corresponding wavelength is 1mm, while at 30 Hz, the wavelength is 10,000 km.
Smartphone and other electronics in your home typically operates at frequencies under 6 GHz, but these frequencies are starting to get crowded.As more devices come on-line, we will experience slower service and more dropped connections.

5G can use spectrum within three key frequency ranges:

– Below 1 GHz: to support widespread coverage across urban, suburban and rural areas.

– 1-10 GHz:to offer a mixture of coverage and capacity.New spectrum in the 3.5 GHz band will be used for 5G services.

– Above 10 GHz:For ultra-high speed 5G services.

Some of these bands are at similar frequencies to existing mobile technologies in use today.

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Higher frequencies typically mean shorter ranges but higher speeds for data.

Foundation Technologies for 5G

1. Millimeter waves
The solution is to open-up some new frequency band, so researchers are experimenting with broadcasting on shorter millimetre waves – those that fall between 30 and 300.
This section of the radio spectrum has never been used before for mobile devices and opening it up means more bandwidth for everyone.

Extremely high frequency (30, 300 GHz)

Foundation Technologies for 5G
1. Millimeter waves
However, there is a catch.Millimeter waves can’t travel well through buildings or other obstacles and they tend to be absorbed by plants and rain.
To get around this problem, we need small cell networks.

5G services in will initially use frequencies around 3.5 GHz.

This is similar to frequencies used by existing cell sites.

Higher frequencies around 26 GHz (sometimes referred to as millimetre waves or mmWaves) will be introduced later, especially where high data rates or capacity are needed.

Millimetre waves have been widely used for many years for point-to-point communication links.

Millimeter waves are used for military fire-control radar, airport security scanners, short range wireless networks, and scientific research.

Foundation Technologies for 5G
2. Small cell networks
Today’s networks rely on large high-powered cell towers to broadcast their signals over long distances (approx. 10 miles or 16km), but remember, higher-frequency millimetre waves have a hard time traveling through obstacles which means if you move behind one you will lose your signal.

Traditional high-powered cell towers

Foundation Technologies for 5G
2. Small cell networks
Small cell networks would solve this problem using thousands of low-power mini base stations (with a range of about 1,000 feet or 300 meters).These base stations would be much closer together than traditional towers, forming a sort of relay team to transmit signals around obstacles.

Low-power mini base stations comprising Small Cell networks

Foundation Technologies for 5G
3. Massive MIMO (Multiple-Input Multiple-Output)
However, this comes with complications.Today’s cellular antennas broadcast information in every direction at once, and all those crossing signals could cause serious interference.Beamforming is the next new technology that aims to solve this problem.

Massive MIMO base stations

Today’s 4G base stations have about a dozen ports for antennas that handle all cellular traffic, but Massive MIMO base stations can support about a hundred ports.This could increase the capacity of today’s networks by a factor of 22 or more.

Foundation Technologies for 5G
4. Beamforming

Massive MIMO base station
Beamforming is like a traffic signalling system for cellular signals.
Instead of broadcasting in every direction, it would allow a base station to send a focus stream of data to a specific user.
This precision prevents interference and its way more efficient.In turn, stations could handle more incoming and outgoing data streams at once.

Foundation Technologies for 5G
5. Full Duplex

Today’s cellular base station requires that communicating entities should take turns sending and receiving signals, in order to avoid collisions. A basic antenna can only do one job at a time, either transmit or receive.This is because of a principle called reciprocity, which is the tendency of radio waves to travel both forward and backward along the same frequency.

Researchers have used silicon transistors to create high speed switches that halt the backward roll of these waves.It’s kind of like a signalling system that can momentarily reroute two trains of signals so that they can get past each other and avoid collisions.That means there’s a lot more getting done on each track a whole lot faster.

5G and Health
https://www.health.govt.nz/system/files/documents/topic_sheets/5g-and-health-aug19.pdf

5G judged safe by scientists but faces tougher radiation rules
https://www.bbc.com/news/technology-51839681

By 2025, 5G will still lag behind 3G and 4G mobile connections.Its mainstream existence faces multiple hurdles.The main reason for this is cost.

References
Computer Networking: A Top Down Approach, 7th edition,,, Pearson/ , April 2016

End of Session

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