1. LO1 – Understand Computer Hardware
1.4 Connectivity Methods

2. Connectivity Methods
Copper cable – known as Twisted pair, Cat5 and Cat6. Twisted pair cable is widely used in 100 Mbps and 10 Gbps networks.
In order to improve performance even more, shielded twisted pair cable (STP) has copper shielding wrapped around each twisted pair and another shield wrapped around the whole cable. This reduces electrical interference and so allows the bandwidth to be higher for any given length.
This is used for LANs as it is relatively fast and cheap and carries a signal over a medium distance i.e. 100m
Fibre-optic cable - Fibre-optic cable has an astounding bandwidth, it is limited more by the electronics either side of the cable than the bandwidth of the cable itself. Fibre optic cable uses light to transmit information rather than electrical signals. Unlike copper cable it is not prone to electrical interference and is suitable for use over longer distances.
The downside of fibre is the cost - it is more expensive that ordinary Twisted Pair network cable therefore it is only cost-effective if there is a very high bandwidth requirement or if the network has very long cable runs.
Unshielded Twisted Pair
Shielded Twisted Pair
Insulation
Cable Shield
Conductor
Pair
Pair Shield
Sheath

3. Connectivity Methods Wireless Technologies
Bluetooth - Bluetooth is a type of radio communication and networking protocol combined.
One advantage with Bluetooth working within a short range is that it only needs a tiny amount of radio power to work. This means it is ideal for battery operated devices such as mobile phones. Another advantage of Bluetooth is that it is completely automatic - every Bluetooth enabled device will sense the presence of another device within range. They can do this because they share a 'network protocol' that allows them to share data. The protocol can reduce interference from other Bluetooth devices that are also exchanging data nearby. For example if Sam's mobile is exchanging data with Tom's mobile this will not interfere with Sarah's mobile also exchanging data with Mary's mobile nearby.
A common use of Bluetooth is 'hand-free' operation of mobiles in the car. The handset becomes 'paired' with the Bluetooth system in the car, so when a call comes in you can accept the call and converse using the car system. This allows you to talk using the mobile but most importantly - keeping your hands on the steering wheel. Bluetooth is also used to exchange files between a smart device and a desktop computer - great for keeping your diary and work in synch.

4. Wi-Fi – To wirelessly connect computer together within the space of a house of office Wi-Fi can be used. All Wi-Fi networks have a piece of hardware called a ‘wireless access point’ (WAP). Radio signals are sent from Wi-Fi enabled devices to the WAP. The WAP can then either relay the signal to another wireless device, or it can convert it into an electrical signal to send on to a wired network.
Microwave – Long distance connections can be established with microwave links. This is a line-of-sight technology, which means each telecom tower containing the microwave dish needs to be in sight of another one a few miles way. Large companies make use of this technology to create private WANs
Infrared communication (IR) - This is one of the earliest types of optical communication and is still very much in use today. It is found in remote controls for televisions, DVD players and most other entertainment devices.
Dimmer lights and other facilities can be also be controlled using infrared.
Infrared uses light that is invisible to us and is just above the red end of the colour spectrum.
The key component of an infrared system is an infrared LED (Light Emitting Diode) to emit the light and a photo-diode in the television or equipment to receive the light.
A digital code within the controller switches the light on and off, this is then picked up as a digital code at the other end. IR works only up to about 10 metres but that is fine for the type of applications it is mainly used for. It will only work line-of-sight. Technologies such as Bluetooth has largely supplanted infrared as a communication method for mobiles and computers.

5. CSU/DSU - Channel Service Unit/Data Service Unit
The CSU is a device that connects a terminal to a digital line. Typically, the two devices are packaged as a single unit. The DSU is a device that performs protective and diagnostic functions for a telecommunications line.
You can think of it as a very high-powered and expensive modem.
Diagrams to show how a new branch of a business could be connected to the existing data centre. This show hardware, communication and security technologies.
Fig i Shows a network connecting two sites using the internet (ADSL Broadband). It uses a VPN Router to connect each end to the network and a modem to connect to the Internet.
VPN = Virtual Private Network which is used here for security reasons so that only the 2 sites can access the network. This is needed as they will be transmitting data across a public network i.e. the Internet which is not secure.
Fig ii Shows the branch connected to the data centre using a leased line with CSU/DSU to connect the network.
Fig i
Branch
Data Centre
Fig ii
Branch
Data Centre

6. Laser communication
Lasers can be used as a communication system. Unlike the tiny LEDs used in fibre-optic communication, this method uses high power laser beams to transmit light signals.
For example, setting up a high bandwidth data link between two line-of-sight buildings can make use of a free-space laser system.
There are commercial systems available that offer Gigabit Ethernet connection speed up to 3 kilometers
One disadvantage of this kind of system is that it is affected by the weather. Fog or haze can block the beams. On the other hand it can be set up very quickly, and easily, making it ideal for setting up a video feed to cover outdoor events at a sports arena.
Laser communication is also used to exchange data between satellites. In space the beams remain strong and tightly focused offering speeds of up to 10 Gbps
Uses
Campus wide communication
Emergency data links (disaster relief etc)
Outdoor events requiring high speed data feeds
Building - to - Building communication
Satellite to Satellite communication
Backup network in case main cabled network fails

7. Satellite broadband
Satellite broadband is an option for remote overseas locations, ships at sea and rural areas where there is only a slow ADSL telephone line and no cable.
A satellite in geosynchronous (in sync with the earth’s orbit) orbit can cover a large part of the world and it appears at a fixed point in the sky. This can be used as an internet broadband link
The major issue with satellite broadband is latency - the satellite is 37,000 Km away and so it takes about 0.7 seconds for a signal to pass between two locations on the ground.
This is usually not a problem for downloading data but it is no good for real-time applications such as online gaming where you need very fast response time.
Conversations in an internet conference call can also be awkward as, due to the lag, you tend to talk over one another.

8. GSM stands for Global System for Mobile Communication
GSM stands for Global System for Mobile Communication. It is a digital cellular technology used for transmitting mobile voice and data services. GSM provides basic to advanced voice and data services including roaming service. Roaming is the ability to use your GSM phone number in another GSM network.
3G/4G - The term 4G stands for ‘fourth generation’ and refers to mobile network technology that enables 4G compatible phones to connect to the internet. The difference between 4G and 3G is that 4G means you can do everything 3G can but faster and smoother than ever before. Web pages load quicker, you can download content within seconds and streaming video and music is free of buffering. Internet-enabled devices can connect wirelessly to the Internet using 3G and 4G (Mobile broadband connectivity)
In 2017, 5G is being developed. However, the problem is that even 4G access is spotty at best in the UK. In rural areas, 3G is a lucky event.