2307054
| Question | Answer |
| What is a wireless network | Any network where information is transmitted wirelessly |
| Name 3 things that wireless communication uses ? & What are they examples of | *Radio waves *Microwaves *Free-space optical communications & Electro-magnetic waves |
| What are electromagnetic waves characterised by & What is the electromagnetic spectrum ? | Their frequency & wavelength & The range of all possible frequencies of radiation |
| How can we transfer info using a simple radio wave? | We must modulate it in some way |
| How can we modulate a radio wave? & What is a carrier wave? | By changing either amplitude or its frequency & The carrier wave is the initial electromagnetic wave |
| What type of modulation is this and explain what's going on | Amplitude modulation and we have our unmodulated radio wave we then have our data and then add the data to the radio wave |
| What type of modulation is this and explain what's going on | Frequency modulation and we have our unmodulated radio wave we then have our data and then add the data to the radio wave |
| What are the range of frequencies measured as and what is it? | Bandwidth & It's the range of frequencies occupied by a modulated wave. Its size depends on the type and ‘depth’ of the modulation. |
| Name the 5 types of wireless links and they're ranges | |
| Name the 5 types of wireless networks | Wireless PAN (Personal Area Network) Wireless LAN (Local Area Network) Wireless Mesh network Wireless MAN (Metropolitan Area Network) Global Area Network |
| What is a Wireless PAN (Personal Area Network) and give an example | Centred around an individual and it's range is typically a few meters an example is bluetooth |
| What is a Wireless LAN (Local Area Network) & what is required | Typical maximum operating range usually within a building & *Wireless Access Point *Wireless Client |
| What is a Wireless Mesh network | It Doesn't require an infrastructure to operate, although they may have a connection to a fixed network. It Requires Ad Hoc and mesh routing capabilities |
| What is a Wireless MAN (Metropolitan Area Network) | Is a connection of several wireless LANs over an area the size of a city |
| What is a global Area Network | Is when Computers and Local Area Networks using wireless connectivity connect to form a bigger network. |
| What is a issue with global Area Network | A major issue is handover from one local coverage area to the next |
| What is an access point | The base station for the network. They normally act as routers and as connections to a fixed wire network. |
| What is a wireless client | A device with a wireless network interface |
| What are, and what are the differences between a BSSID and a SSID? | A BSSID is the Basic Service Set Identifier. It is the MAC address of the Access Point. A SSID is an ‘informal’ name for a BSS, and can be chosen by the AP administrator. |
| What are, and what is the relationship between, a BSS and an ESS? | A BSS is a Basic Service Set – an Access Point and its connected devices A ESS is an Extended Service Set. An ESS is a set of connected BSSs that share the same SSID, security and back-end wired network (distribution system). A device sees all APs in a ESS as single BSS. |
| When using extended service set are devices able to roam between AP's without interrupting communications | Yes |
| What is the difference between ad hoc and infrastructure mode in wireless networking? | In ad hoc mode there is no access point and devices communicate directly with each other. The SSID of the network is chosen by the client that ‘starts’ the network and it is broadcast in turn by a randomly chosen member of the network. In Infrastructure mode devices are all clients, which then connect to dedicated Access Points. |
| What is Wi-Fi Direct | A standard that allows a device to become an AP for ‘clients |
| What are the two types of roaming in Wi-Fi networks and what do they do | Internal roaming - Clients move from one AP to another in the same ESS when the first AP becomes too weak External roaming - Client moves into another WLAN, typically from a different provider & the client must have software installed to ensure sessions persist, so no loss of communications, during the transfer |
| What can happen when radio signals overlap each other | They can interfere with one another |
| What 3 issues can interference cause? & How can you prevent them? | *Loss of data *Reduced performance *Total loss of connectivity & By making sure that adjacent base stations do not operate on the same frequency |
| What encryption and integrity protocols were used with WEP, and why are these a problem in modern networks? | RC4 was used for encryption & CRC32 was used for integrity |
| Why is physical layer security important on a wireless network? | Wirless is an open medium so anyone can capture data packets, unlike a wired network where some effort has to be made to tap the cable. |
| What is Wi-Fi Protected Setup and why is it weak? | Wi-Fi Protected Setup enables users to easily setup wireless communications using WPA or WPA2 with a secure pre-shared key (secret). & The pin method because all the possible pins could be tried by an attacker to find the correct one to connect to the Access point and then obtain the pre-shared key |
| What is the relationship between WEP, WPA and WPA2? | WEP uses the secret key + IV and a RC4 algorithm to achieve security WPA was a half-way house between WEP and WPA2. It solved the problems of WEP by replacing the simple key generation (secret key + IV) with the Temporal Key Integrity Protocol (TKIP). WPA2 implements the mandatory requirements of the current security standard for WLANs. It replaces RC4 with AES |
| How do some AP(Access Protocols) prevent the issues with WPS | By slowing or disabling the PIN method after a specified number of failed connections |
| What is? Velocity Frequency Wavelength | Velocity - The speed in a given direction Frequency - Number of cycles per second Wavelength - Distance travelled in one cycle |
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