Our world is connected by wired and wireless digital communication systems. Data flows around these systems, carrying information about our personal and work lives and providing us with entertainment and news. Digital devices exchange data and communicate with each other and with larger systems. Understanding the way in which devices communicate will help you to understand why things do not work as expected and will enable you to stay connected to the streams of data that drive our world. By the end of this chapter, you should be able to select the most appropriate digital communication for a particular situation, after considering how each option would affect the quality of a connection.

As we transfer more and more data, it becomes more important that we understand how to increase the speed at which we can transfer it. If we do not, transferring more data will mean that transfer times will increase.

Bandwidth is the number of bits that can be carried by a connection in one second. The speed at which devices can transfer data depends on the bandwidth of the connection.

You can think about a data connection as being like a water pipe. In the same way that a large water pipe can carry a large amount of water, a connection with a large bandwidth can carry a large amount of data.

IMPACT ON USER EXPERIENCE

A higher bandwidth means that more data can be transferred every second. This makes uploads and downloads faster. It also makes it possible to do things that require lots of data to be transferred in short amounts of time, such as multiplayer online gaming or high-definition video streaming.

When streaming video, all of the data does not need to be downloaded before playback can start. Instead, a portion of the video data is stored temporarily in an area of memory called a buffer. The video will not start until there is enough data in the buffer to play a few seconds of video. While those few seconds are playing, more data is downloaded to fill up the buffer. If the buffer is empty, there is no more video to play and it will pause until more data is downloaded. To avoid the buffer becoming empty, data must be constantly downloaded into the buffer, filling it up at a rate faster than it is emptied. Imagine a glass of water being repeatedly filled up from a big bottle. The bottle is like the full video data file and the glass is like the buffer that holds the data ready to be used.

As well as bandwidth, the speed of data transfer also depends on latency. Latency is the delay in the time it takes to send data between devices. If you think again about a data connection acting like a water pipe, latency is the average time that it takes for a drop of water to flow through the pipe. You can identify latency by 'pinging' a domain. When you ping a domain, you send a packet of data to a server and the packet of data is immediately returned by the server to the originating device. The 'ping time' is the amount of time it takes for the packet of data to make the return trip.

IMPACT ON USER EXPERIENCE

In online gaming, the game will play smoothly if the bandwidth is adequate. However, if the latency is high, events in the game will lag and the game will not seem responsive to the player's commands. When watching live television, high latency will result in a delay between the real-time events and the video being received for playback.

When devices transfer data, they can be affected by many factors that stop bits from reaching their destination. These bits then have to be sent again, which slows the overall data transfer rate.

TRANSFER METHOD

Wireless methods have to work on a limited number of frequencies. In comparison, copper cable can carry more frequencies than wireless methods. This means that cabled methods can have more bandwidth available to them than wireless methods.

INTERFERENCE

Other electromagnetic signals disrupt or interfere with wired and wireless signals. For example, interference can be caused by signals from wireless devices, wireless routers and appliances emitting electromagnetic fields like fridges and microwave ovens. Cabled connections can be shielded from this interference by having the wires wrapped in a thin layer of metal.

BLOCKAGES

Walls and furniture reduce the strength of wireless signals. This reduces the available bandwidth.

DISTANCE

The strength of a wired or wireless signal is reduced as the distance that it has to travel increases.

Devices can connect directly to each other using wired or wireless methods. This is called device-to-device communication.

Table 4.1 shows some examples of device-to-device communication.

When two or more computers are connected, a network is created. There are four major types of network.

LOCAL AREA NETWORK

A LAN is a network that connects digital devices that are in a small geographical area, like a building or group of buildings that are close to each other.

A WAN is a network that is spread over a large geographical area. WANs are often used to connect different buildings owned by national and international businesses, law enforcement agencies, health and education organisations and government departments.

Some organisations launch their own satellites to provide connectivity for their own global WANs. WANs often use connectivity provided by a third-party telecommunications company, often linking LANs together through the internet. Because of their wider reach, WANs often have slower transfer speeds than LANs.

One example of WAN is the internet.

A PAN is a group of connected devices that are all near an individual user. For example, a user could connect their smartwatch to their smartphone, which is connected to their laptop and home cinema speaker system. Devices in a PAN can either be connected to each other directly or connected through access points (see page the next section for more information about access points). When a PAN only uses wireless connectivity, it can also be referred to as a WPAN (Wireless Personal Area Network). However, the general term PAN is more commonly used to refer to all types of PAN.

Tethering is the process of connecting a host device, such as a smartphone or a tablet device, that uses a mobile broadband connection with one or more other devices. This enables the other device or devices to share the host device's broadband connection.

Mobile phone network providers can enable or disable tethering as part of the service agreement. Some network providers charge more for this feature to be enabled.

Satellites transmit data to and receive data from digital devices. Digital devices use antennae to receive the radio signals that satellites transmit.

The benefit of satellite communication is that the number of satellites means that the system is always available. It also cannot be affected by power shortages.

The drawback is that satellite signals do not pass through solid objects. This means that they will not work in areas with tall buildings or in tunnels. Signals can also be affected by atmospheric weather conditions such as heavy snow or rain.

GPS

Satellite communications are used for GPS. Navigation aids make use of GPS signals to calculate the exact location of a device. GPS signals are sent from a network of 24 satellites orbiting the Earth. At any one time, a device will be within view of approximately 12 of these satellites. However, a view of only 4 satellites is required to calculate an accurate location, asexplained in video ICT#12

For more information about navigation aids, see Unit 1 Digital devices

TELEVISION

Digital Video Broadcasting (DVB) is the internationally accepted standard method of broadcasting digital television. DVB-S (Digital Video Broadcasting — Satellite) is one example of DVB. A video signal from the broadcaster is transmitted using a large antenna on Earth to one or more satellites, which then broadcast the signal back down to Earth. A satellite television viewer will have an antenna installed, and this receives the signal and sends it to a set-top box. The set-top box decodes the signal and converts it so that it is ready to be sent to a television. Some televisions have decoders installed, so the antenna can be connected directly to the television rather than requiring a set-top box to decode the signal first.

DVB-S2 and DVB-S2X are newer digital broadcasting standards. They provide more functionality, such as High Definition Television (HDTV), interactive services and internet access.

TELEPHONE

Satellite communication is also used to allow people in remote areas to place voice calls using satellite telephones.

MILITARY

The military in many countries use satellites for communication systems, such as the Global Command and Control System.

ANALOGUE TELEVISION AND RADIO

Transmitters broadcast television and radio signals that are received by a viewer's antenna. This antenna sends a signal through a wire to the television or radio receiver, which converts it into images and audio.

DIGITAL TELEVISION

DVB-T (Digital Video Broadcasting — Terrestrial موجود على الكرة الأرضية) is a method of DVB where the transmitters are based on Earth, rather than in orbit as they are in DVB-S. To receive digital television broadcasts transmitted by DVB-T, viewers can use the same antenna that they use to receive analogue broadcasts. They do not need a special antenna.

DVB-T2 is a newer standard that provides more functionality, such as High Definition Television (HDTV) and interactive services.

DIGITAL RADIO

DAB (Digital Audio Broadcasting) is used in Europe and the Asia Pacific region. It is broadcast in the same way as DVB. DAB provides more radio stations and can also carry text data that DAB receivers can display. The text data can include the time, name of the station and details of the music being played.

Cables

Devices can use cables to communicate with each other via a wired connection. There are many different types of wired connection. Some are used for many different purposes, such as USB. Others are only used to meet one particular need, such as Ethernet.

Some of the uses for different wired connection types are given in Table 4.3.

USB

USB is a very common connection type. USB has been through a number of revisions, and each revision allows faster data transfer speeds. This development of standards is common with all types of connectivity. This progress is made necessary as digital devices become more complex in their features and functionality. Ethernet allows a user to connect to wired networks. As Ethernet technology develops, the speed at which data can be transferred between devices is improved. Ethernet cables can be 100 metres long before the signals they carry start to lose quality.

The Different Types of Wireless Communication

• Satellite Communication. Satellite communication is a crucial form of wireless communication. ...

• Infrared Communication. ...

• Broadcast Radio. ...

• Microwave Communication. ...

• Wi-Fi. ...

• Mobile Communication Systems. ...

• Bluetooth Technology.

Wi-Fi is the wireless technology used to connect computers, tablets, smartphones and other devices to the internet.

Wi-Fi is the radio signal sent from a wireless router to a nearby device, which translates the signal into data you can see and use. The device transmits a radio signal back to the router, which connects to the internet by wire or cable.

What is a Wi-Fi network?

A WiFi network is simply an internet connection that’s shared with multiple devices in a home or business via a wireless router. The router is connected directly to your internet modem and acts as a hub to broadcast the internet signal to all your Wi-Fi enabled devices. This gives you flexibility to stay connected to the internet as long as you’re within your network coverage area.

Mobile broadband refers to internet delivered on a cellular network. This type of connection utilizes cell towers to transfer data to your mobile phone, keeping the internet portable for millions of users.

From 1G to 5G

The timeline and history from 1G to 5G took just over 40 years since the introduction of wireless cellular technology. And a lot has changed since then.

• Cell phones have become smaller.

• Download speeds have become faster.

• Text messaging has come (and almost gone).

• Surfing the internet with phones became common.

• The steam of social media posting continues.

• And apparently, there’s an app for nearly everything now.

1G

main feature:

• Launched in 1979 / 1981 and offered making phone calls (wirelessly).

• Although being a revolutionary technology at the time, 1G suffered major drawbacks from today’s standards. Listening to somebody over a 1G network was difficult due to the low sound quality. Coverage was also shoddy, with large amounts of static noise and background crackling. No roaming support was provided either. Security didn’t exist over a 1G channel because there was no encryption, meaning anybody with a radio scanner could drop in on a call. Download speed over 1G was also incredibly slow

2G

Launched in 1991.

offered SMS, MMS and data

2G provided some significant mobile talk advancements, introducing encrypted calls (nobody could drop in on your call unwanted anymore). 2G also improved sound quality, reducing static and crackling noises while you were talking. 2G’s download speeds were also significantly faster (but still incredibly slow by today’s standards) than 1G, averaging at about 0.2 Mbps during its lifetime.

The 2G network also allowed us to transfer bits of data from one phone to another, enabling access to media content on cellphones such as ring tones. Because we could now transfer data, 2G also gave us some basic smartphone functionality.

3G

Deployed in 2001

main feature: Compared to 2G, 3G had 4 times the data transferring capabilities reaching up to 2 Mbps on average.

Because of this increase, video streaming, video conferences, and live video chat (remember good old Skype) became real. Emails also became another standard form of communication over mobile devices.

What made 3G revolutionary, though, was the ability to surf the internet (basic HTML pages at the time) and stream music on mobile. Although 2G did offer the same features, they weren’t as advanced as what 3G had in terms of download speed.

As the 3G era continued, improvements to the network were made, increasing speeds and support.

It wasn’t until 2007 that the original iPhone came out, soon to dominate the smartphone (and cellphone) marketplace in only a few years.

4G

Introduced for commercial use in Norway near the end of 2009, 4G offered today’s standard services.

Starting at a minimum of 12.5 Mbps-max 40mps, 4G provided high-quality video streaming/chat, fast mobile web access, HD videos, and online gaming. Compared to a simple SIM card switch from 2G to 3G, mobile devices needed to be specifically designed to support 4G.

Bluetooth is a wireless technology that uses a radio frequency to share data over a short distance, eliminating the need for wires. You can use Bluetooth on your mobile device to share documents or to connect with other Bluetooth-enabled devices. For security reasons, Bluetooth devices must be paired before they can begin transferring information.

Common Bluetooth applications are:

1. Connecting mobile phones to each other to exchange pictures,ring tones, music etc

2. Connecting computer peripherals like mice, keyboards, printers etc to a computer.

3. Connecting headsets to mobile phones for hands free operation (Bluetooth car kits)

Radio Frequency IDentification (RFID)

is a form of wireless communication that uses radio waves to identify and find objects. ... RAIN RFID is used in a wide variety of applications, including inventory management, asset tracking, and shipment verification. مثل ما يوضع في المحلات على الملابس لاكتشاف السرقة

IR wireless is the use of wireless technology in devices or systems that convey data through infrared (IR) radiation.

Infrared wireless networking uses infrared beams to send data transmissions between devices. Infrared wireless networking offers higher transmission rates, reaching 10Mbps to 16Mbps. As expected, infrared light beams cannot penetrate objects; therefore, the signal is disrupted when something blocks the light.