CCNA Wireless IUWNE 640-722
Wi-Fi Technology Overview
The Wi-Fi technology is based on the RF radio frequency signals that enable fast data transfers for indoor range up to 70 meters and outdoor range up to 250m. The speeds, range, coverage, and other characteristics depend on the type of the Wi-Fi signals.
Wi-Fi networks are professionally called WLAN networks. WLAN – Wireless Local Area Networks are local networks based on the wireless technology.
The Five Generations of the Wi-Fi (Wireless Medium)
Wi-Fi technology has five generations. Each generation is defined by the IEEE 802.11 family of standards. These standards define various aspects of each generation.
- Frequency
- Frequency channels
- The number of channels
- The bandwidth of channels
- Modulation techniques – the way radio frequency signals are formed to enable data transfer.
As a result of this, every generation of the Wi-Fi (WLAN standard) has its own characteristics:
- Speed of wireless data transfer
- The range of wireless signals
- The ability of the signals to handle the physical obstacles.
The five generations of Wi-Fi technology are:
IEEE standards
The IEEE Standards called these five generation s as the below:
- 1st generation: 802.11a – usually called a.
- 2nd generation: 802.11b – usually called b.
- 3rd generation: 802.11g – usually called g.
- 4th generation: 802.11n – usually called n.
- 5th generation: 802.11ac – usually called ac.
Wireless Terminology (Vocabulary) and topology:
- Ad hoc mode (Operates on half duplex)
- BSS (The range for each device or computer is BSS)
- IBSS(Ad hoc, Peer 2 Peer )
- Infrastructure mode
- AP(Hot Spot)
- BSA (Basic Service Area)/Cell
- SSID
- DS(Distribution System) is the path from AP to any other devices like Server, Internet …
- WLC – Controller mode
- ESS (Extended Service Set): Extended Service Set is a larger network made of access points that are connected to the wired network device – a router
- Roaming (seamless movement among APs is called roaming)
Wireless Standards and Regulatory Bodies:
The standards are provided and organized by IEEE and WLAN works under the layer 1 and 2 standards.
- Layer 1 and 2
- 11
- Public Protocols
- Modulation
- Framing
- Frequency
- Interoperability testing
- Wi-Fi Alliance
- Regulation Organization
- FCC: Federal communication Commission
- ETSI: European Telecommunication Standard Institute
- TELEC: Telecom Engineering Center
- BRAI: Broadcasting Regulatory Authority of India
Radio Frequency 101:
RF signals that are used to send bits forward and back to our network.
- 1Hz, KHz, MHz ,GHz, THz
- Wave Length (How wide one cycle is)
- How tall (Amplitude) more energy = more Amplitude
Note: what a node does when it wants do connect an AP? Only waves nothing more
Note: The lower the frequency the longer the wavelength
Note: The higher the frequency the shorter the wavelength
RSSI (Received signal strength identifier): RSSI is used to identifies the length of the signal from receiver
RSSI – Noise = Signal to noise ratio (SNR)
How good RF Signals get bad:
- Path loss and Scattering (Free of charge)
- Lead(other obstacles absorb the signals)
- Mirror Mirror (Reflection, Multipath, Fade)
- Long range atmosphere refraction
- Noise(Interference with RF)
Basic Elements of Wi-Fi Networks
Every Wi-Fi network consists of these four basic elements.
- Access point
- Distribution system
- Wireless medium
- Station
Access point – AP
The wireless access point (AP) is the heart of the all Wi-Fi networks – key device in WLAN formation. It is wireless gateway and bridge between wireless networks and wired networks. AP enables that all connected Wi-Fi devices can exchange information with the wired network. Usually the most home wireless networks have a wireless router. Wireless router consists of many devices. Often it is the modem at the same time, so you have a DSL connection to the internet, router with 4 Ethernet ports and access point.
Distribution System – DS
802.11 standards, which define how all WLAN networks work, define the distribution system as a combination of bridging engine and backbone network. The distribution system has two functions:
- Connecting access point to the backbone – usually internet.
- Connects two different access points over a wired network.
Stations – Wireless Clients
The stations or wireless clients are all the devices that support Wi-Fi connection. Together with access point they are the most important elements of the WLAN formation. Stations, just like wireless medium of the access points, work according to five types of 802.11 networks. Today there are more and more different kinds of devices which can connect to the wireless access points.
Wi-Fi client is going through the five stages:
- Scanning
- Joining
- Authentication
- Association
- Re-association
Scanning
The scanning is the process of finding the Wi-Fi network. Classical wired networks use cables for the interconnection. In the wireless network, the first thing you need to do is to identify the appropriate network. Wi-Fi clients use the scanning to find existing networks in the area. After scanning, the client can choose to join one of the available wireless networks.
Joining
Joining does not guarantee the network access. It is only the first step for the client to be connected to the WLAN network. After joining, the client also needs to pass the authentication and associate stage.
The client can connect to the BSS in two ways:
In the manual joining the client chooses the BSS manually. In the automatic joining wireless client picks the best access point according to a power level and signal strength.
In the both cases, parameters configured on wireless client and access point, need to match.
Authentication
In wireless networks, you don’t need the physical access to the network. You only need to be within the range. Wireless authentication is the security method in the wireless networks
Association
Association is the process that enables the client the actual access to the WLAN network. It is the same like plugging the cable into the wired network. It is not possible to be associated in more than one access point.
Re-association
The association can occur only in the ESS wireless network. The client, in this case, associates to the other access point in the same ESS. It is triggered when the client detects that the other access point have a stronger wireless signal.
Extension of the Wireless Network
There are different kinds of wireless routers. They can work on different standard (different Wi-Fi generation). The most time they are used as a standalone wireless router. In some cases it could be the problem with insufficient range and coverage and low speed in some part of your home. So you need to extend your wireless network. This can be done in seven ways.
What is a Broadband Wireless Router?
The Broadband wireless router is a network device which can have the following functionalities:
- Wireless access point
- Network Switch
- Router
- Firewall
- DHCP server
- NAT
- Modem (DSL, cable, fiber optics)
Wireless Authentication Types
The Wireless authentication types are associated with the SSIDs configured on the wireless access point. If you need different types of wireless authentication, you need different SSIDs. Each SSID can have different security parameters.
Wireless authentication has two levels of security:
- Open or Shared-key authentication
- EAP – Extensible Authentication Protocol
Open and shared-key authentication use WEP. WEP doesn’t give you a proper security level. Shared-key authentication is especially vulnerable.
Note:
For the EAP you need a Radius server, while for the Open and Shared-key authentication there is no need for any external device.
WEP Authentication Protocol
WEP – Wired Equivalent Privacy has never deserved the meaning of its name. It is really easy to crack WEP. It can be done in less than a minute.
There is a 40, 64-bit, 128-bit and 256-bit WEP. It is a lot easier and more user-friendly to use a passphrase than a WEP key. When you use the passphrase, it is converted to keys in the hexadecimal format.
The biggest problem with WEP is the static key which does not change during a session. The length of the key (64-bit, 128-bit and 256-bit WEP) only extends the time needed to crack the wireless network. The only advantage of WEP is that all Wi-Fi equipment supports it. Even with the older wireless cards and access points you can configure WEP as the wireless internet security.
WEP Disadvantages
- It’s very easy to crack
- It slightly reduces a performance
- It uses a static key
WPA Authentication Protocol
Wi-Fi Alliance has launched WPA in October 2003. WPA – Wi-Fi Protected Access was much better replacement of WEP. The biggest WEP problem is that it uses a static key. WPA has solved the WEP problems with better encryption and authentication.. There are two versions of WPA.
- WPA – Personal Mode
- WPA – Enterprise Mode
WPA – Personal Mode:
Personal mode WPA has PSK authentication and TKIP/MIC encryption.
WPA – Enterprise Mode:
Enterprise mode WPA has EAP authentication and TKIP/MIC encryption.
WPA Advantages
- Much better encryption mechanism
- Uses the temporary key – TKIP
- Compatible with many older devices.
What is WPA2?
Soon after WPA, Wi-Fi Alliance has launched WPA2. Thanks to PSK authentication, it is backward compatible with the WPA. Besides PSK, WPA2 uses much better encryption standard – AES. IEEE has defined the WPA2 with the 802.11i standard.
WPA2 Advantages
- Provides stronger data protection and network access control
- Uses better encryption – AES
- It can use TKIP for interoperability with WPA
- Impossible to crack without access to the network
- Older equipment does not support it
WPA2 is the latest WPA implementation. It is based on 802.11i standard and provides government grade security. The WPA2 uses better encryption – AES comparing to TKIP used by WPA. You can also use TKIP encryption which is used for interoperability with WPA.
Different Modes of WPA and WPA2
WPA and WPA2 in Personal Mode
Personal mode was designed for home and office environment. Here you do not need the special server dedicated for the wireless security. The security level of the wireless network is based on the PSK – pre-shared key or a passphrase.
WPA and WPA2 in Enterprise Mode
In the enterprise mode you need to have dedicated authentication server – RADIUS server. This mode meets with the rigorous requirements of the enterprise security.
Both versions of WPA use 802.1X/EAP Authentication. WPA has TKIP encryption, while WPA2 has AES.
According to this, we can divide all Wi-Fi Certified equipment in four groups:
- WPA-Personal
- WPA2-Personal
- WPA-Enterprise
- WPA2-Enterprise
Here is a brief overview of these four groups. They are divided by the authentication and encryption methods that they use:
|
WPA |
WPA2 |
| Enterprise mode |
Authentication:802.1X/EAP
Encryption: TKIP/MIC |
Authentication:802.1X/EAP
Encryption: AES/CCMP |
| Personal mode |
Authentication:PSK
Encryption: TKIP/MIC |
Authentication:PSK
Encryption: AES/CCMP |
Setting Up a Wireless Network – Overview
Setting up a wireless network has never been easier. With these five simple steps you can set up your own wireless network in a few minutes.
- Get the Right Equipment
- Connect the Cables
- Position the Wireless Router
- Configure the Wireless Router
- Connect the Clients to the Wi-Fi Network
1. Get the Right Equipment
The first step is getting the right equipment. You need the following devices:
- Internet connection
- Modem
- Wireless router
- Clients with Wi-Fi adapters
You can have the modem and the wireless router in the same device. I have a DSL port on my wireless router. My wireless router is directly connected with the telephone cable to my ISP.
2. Connect the Cables
The second step of setting up a wireless network is to physically connect equipment with the cables. This can be done in two steps:
- Setting up a modem and internet connection
- Setting up a Wireless router
Setting Up the Modem and Internet Connection
The ISP – Internet Service Provider is responsible for setting up your internet connection and a modem. If it wasn’t done by them, follow the instruction you get with a modem. The modem can be the DSL – digital subscriber line modem and the cable modem.
Setting Up a Wireless Router
The router has four kinds of ports:
- 4 Ethernet ports
- Internet connection
- USB port
- Power
If are looking from the left, first there are 4 Ethernet ports. The ports are for connecting UTP Ethernet cables to your computers in a wired network. In the middle there is a port with the yellow label Internet. This is also the Ethernet port, but this one you need to connect to the modem with the UTP cable.
To the USB port you can plug into your external hard disk and you will have a NAS – Network Attached Storage Server. The last port is for the power cable.
3. Position the Wireless Router
In positioning the wireless router the most important is to enable the maximum wireless signal all over your place. The third step in setting up a wireless network can be summed up with the following:
- Place the wireless router in a central location.
- Avoid physical obstructions – walls and metal objects.
- Set up the wireless router away from the electrical devices, especially microwave ovens, cordless phones and baby monitors.
4. Configure the Wireless Router
In setting up a wireless network it is critical to configure the appropriate wireless security. If you apply these five steps, you can get the maximum security:
- Change a Default Password
- Change Default SSID
- Do Not Use WPS – Wi-Fi Protected Setup
- Enable the WPA2
- Enable a MAC Address Filtering
- Change a Default Password
The very first thing you should do on the wireless router and access point is to change the default password. All these devices have a web user interface for their configuration. This webpage is protected with the username and password.
To be able to access the device’s web interface, the first thing you should know is the IP address.
Password Recommendations for the Maximum Wireless Internet Security
- Do not use the default password
- Mix of letters, numbers and non-alphanumeric characters
- Use both small and capital letters
- Don’t use the words from the dictionary
- Change the password every month or two
- Change Default SSID on Your Wireless Router
The second most important thing you need to change is the default SSID or a network name. Default SSIDs, listed below, are a sign for hackers that the Wi-Fi network is easy to crack.
- Linksys
- NETGEAR
- D-link
- default
Recommendations for SSID
- Don’t use the default SSID
- Don’t use your name, address, or any other personal information
- Don’t use the passwords that you are using on your computer
- Use both letters and numbers
- Use the maximum allowed length
- Change SSID every month or two
- Do Not Use WPS – Wi-Fi Protected Setup
A major security flaw was found with the WPS – Wi-Fi Protected Setup feature. All recent models of the wireless routers support the WPS and it is enabled by default. Thanks to this flaw, a hacker can recover the WPS PIN and WPA2 key in a few hours. So please disable the WPS feature on your wireless router.
- Enable the WPA2 for the Maximum Wireless Internet Security
Enable the WPA2 on the wireless router or access point. Do not use WEP in any case.
WPA Recommendations for the Maximum Wireless LAN Security
- Use WPA2 – Authentication PSK, Encryption AES, for personal use
- Use WPA2 – Authentication EAP, Encryption AES with the Radius server for enterprise
- Use the maximum length for the WPA2 key
- Use combination of small and capital letters, numbers and non-alphanumeric characters for WPA2 key
- Don’t use dictionary words for the WPA2 key
- Change WPA2 key every month or two
5. Enable a MAC Address Filtering for the Maximum Wireless LAN Security
All wireless routers and access points have a built-in feature to enable the MAC address filtering. You need to find out the MAC addresses of all the clients in your wireless network. After you specify them in MAC address filtering table, only these clients can be in your wireless network.
Have You Ever Been Hacked?
Have you been a victim of some hacker? ? Poor wireless internet security has almost ruined the life of some persons.
5. Connect the Clients to the Wi-Fi Network
Configure the appropriate parameters for your clients – computers, smartphones and tablets. SSID and the security settings – encryption, authentication and the key have to match with the ones you have on the wireless router.
802.11i – A New Generation of the Wireless Network Security
802.11i is standard that specifies security mechanisms for wireless networks. It is an amendment to the IEEE 802.11 with the full name IEEE 802.11i-2004. Practically is implemented as WPA2 also called RSN – Robust Security Network. Its main task is to replace security compromised WEP by the use of the AES – Advanced Encryption Standard.
Application to 802.11i
There are two points of the decision to allow the 802.11 access:
- Access Point
- Authentication Server (usually Radius)
The decision is decided by authentication and 802.11 Policy decision token is Master Key.
Master Key – MK
- Symmetric key that represents client’s and Radius server’s decision during one session
- Only the client and authentication server has it
- Decision for authorization is based on the MK
Pairwise Master Key – PMK
- Fresh symmetric key that controls client’s and access point’s access to the wireless network during the session
- Only clients and access point can produce the PMK
- Derived from MK
- Radius server distributes PMK to the access point
- PMK possession demonstrates authorization to access the wireless network during the session
Pairwise Transient Key – PTK
- Generated from PMK
- Temporal operation key used to secure multicast and broadcast traffic
Authentication Procedure
802.11i Operational Phases
Security Capabilities Discovery
- Access point advertises the network security capabilities
Client knows:
- SSID
- Authentication method
Access Point knows:
- SSID
- Authentication method
802.1x Authentication
- Centralized network admission policy decisions at the access point
- To mutually authenticate client and Radius server
- Generation of Master Key
- Generation of Pairwise Master Key as an access authorization token
At the end of successful authentication:
- Radius server and client have established a session
- Radius server and client have the master key
- Radius server and client have derived pairwise master key
- Radius has distributed pairwise master key to the access point
Radius-based Key Distribution
- Radius server moves (not copies) Pairwise Master Key to access point
802.1x Key Management
- Binds Pairwise Master Key to client and access point
- Generate fresh PTK
- Proving that each peer is live
- Synchronization of PTK use
- 4-way handshake used to derive, bind and verify PTK
802.11i Data Transfer
802.11i have 3 protocols for data protection:
1) CCMP – Counter Mode with Cipher Block Chaining Message Authentication Code Protocol
2) WRAP – Wireless Robust Authenticated Protocol
3) TKIP – Temporal Key Integrity Protocol – for legacy devices only
- Unprotected packets are never send
- The authenticity of message origin
- Protection of source and destination address
- Use of strong cryptographic mechanism
Wireless Antennas:
You can find two basic types of Wi-Fi antennas:
- Directional
- Omnidirectional
Omnidirectional Wireless Router Antenna
The omnidirectional wireless router antenna is used for point to multipoint connections. The omnidirectional antenna transmits the radio signals in all directions. In most cases it has lower gain than directional wireless internet antenna.
If you are trying to make your wireless signal stronger and the range longer, the best Wi-Fi antenna for you is omnidirectional antenna.
There are five types of omnidirectional wireless router antenna:
- Vertical Omnis
- Ceiling Domes
- Rubber Ducks
- Small Desktops
- Mobile Vertical Antennas
Directional Wireless Router Antenna
The directional wireless router antenna is mostly used for point to point connections. If you are trying to connect to remote wireless access points or the wireless routers, the best Wi-Fi antenna is the directional wireless router antenna.
There are four types of directional antennas:
Homemade Wi-Fi antenna
The homemade Wi-Fi antenna is not the best Wi-Fi antenna, but it is for sure the cheapest. You will be surprised by how easy is to build your own homemade Wi-Fi antenna. You could make it very easy in your home for almost free.
Wireless Signal Booster Overview
Wireless signal booster is a device which boosts the wireless signal and increases the effective range and the coverage of the wireless network.
Different Types of the Wireless Signal Booster
On the market you can find different versions of the wireless boosters:
- Wi-Fi signal booster
- cellular signal booster
- software Wi-Fi booster.
For boosting your Wi-Fi signal you can use six methods:
Wi-Fi Signal Booster
Wi-Fi signal booster is a wireless booster for Wi-Fi signals. We can group Wi-Fi signal boosters according to the position in the Wi-Fi network. One group is on the side of the wireless router and the other is on the client side.
The types of the Wi-Fi signal boosters:
- wireless signal booster for the wireless routers and access points
- Wi-Fi booster for the clients
Wireless Signal Booster for the Wireless Routers
Wi-Fi booster for wireless routers expands the range of a Wi-Fi network by repeating the signal from the wireless router and redistributing the Wi-Fi signal to new locations. On the right, you can see Amped SR300 – Wireless signal booster for the wireless router. It has the best marks from the customer reviews on the Amazon.
Wireless Repeater Overview
Wireless repeater or Wi-Fi repeater is a device which enables you to extend the range and improve the coverage of your wireless network.
Parts of your home have weak Wi-Fi signal or even they don’t have a wireless signal at all. There are seven ways to boost the range and improve the coverage.
- Increasing the power of the wireless router.
- Using the Wi-Fi signal booster.
- Finding a better place for the Wi-Fi router.
- Using of secondary access point.
- Using the newer generation of Wi-Fi.
- Using of Wireless repeater.
- Using of Wi-Fi antenna.
Wireless repeater
Wireless router (access point) connected to the internet is called a root wireless router (root access point). Other wireless router or access point which has a wireless connection to the root is called repeatedly.
Wi-Fi repeater acts as a relay between the root wireless router and the wireless client. It receives the signal from the root wireless router and forwards this signal to the client. When wireless traffic is going from the opposite direction, wireless client sends the signal to the Wi-Fi repeater, which then forwards the signal to the wired wireless router.
Two Kinds of the Wi-Fi Repeaters
Wi-Fi repeaters can be grouped by how they are connected to the root wireless router. They can use WDS – wireless distribution system or not.
- WDS repeater
- non-WDS repeater.
Non-WDS Repeater – Wi-Fi Range Extender
Non-WDS repeater connects to the root wireless router as a wireless client. The devices, wireless repeater and root wireless router, needs to have the same SSID. Non-WDS repeaters are usually called wireless range extenders.
Setting up the Wireless Range Extender
During the setup of the wireless repeater without WDS, take care of the following things.
- Use the same channel like a root wireless router
- Use the same SSID like the root wireless router
- Use the same security parameters (security type, passphrase)
- Don’t place the repeater too far away from the root wireless router.
WDS Repeater
Wi-Fi repeater uses a wireless distribution system for connection to the root wireless router. The WDS wireless connection is dedicated only for wireless connection between the repeater and root.
Wireless Site Survey
What is Wireless Site Survey?
Wireless site survey should be the first step in deployment any new wireless network. Wireless site survey, sometimes called an RF site survey, is the process of planning and designing a wireless network.
Types of Site Surveys
There are three types of wireless site survey:
- Passive
- Active
- Predictive.
Passive Survey
Passive site surveys are performed without connecting to the access point or wireless router. The result is the most often:
- Initial site surveys
- Validate the final RF settings
- Identify the rogue access points
- Locate the locations with the possible RF problems.
Active Survey
In the active wireless site surveys you need to connect to the access point. The active wireless site surveys can be performed in two ways:
- BSSID – Basic Service Set Identifier Method
- SSID – Service Set Identifier Method.
BSSID Method
In the BSSID method client is locked only to one AP (AP prevents that client from roaming).
SSID Method
In SSID method client associates to the one SSID and then it roams between different APs. The method is usually used for survey of multiple APs and is done after deployment.
The Site Survey Process
The process of the wireless site survey consists of these steps:
- Getting the exact requirements
- Getting the proper maps
- Visual inspection
- Evaluation of the existing network infrastructure
- Identify the coverage areas
- Choose the preliminary locations for the access points.
- Verification of the access point locations.
- Document the APs locations
Getting the Exact Wireless Requirements
To be able to identify the optimum number and locations for the access points, you must have a real understanding of the different requirements for that particular site:
- The primary requirements
- Type of the traffic (voice, data, video..)
- Type of the facility
- Type of the wireless clients
- The Customer facility requirements
- Single floor/multi-floor
- Indoor/outdoor
- Warehouse/office
- The wireless clients requirements
- Minimum RSSI – Receiver Signal Strength Indicator
- Minimum SNR – Signal to Noise Ratio
- Delay and Jitter
- Maximum transmit power (Tx)
Getting the Maps
Collect the maps and blueprints of the site location. If you can’t get them, you will need to make them by yourself. The diagrams should have exact locations of walls, corridors, floors… Wireless site survey applications have option to import the maps.
Visual Inspection
The next step in the wireless site survey is a visual inspection of the facility. Note any obstacles that have an impact on the Wi-Fi signals (metal racks and partitions or any other barriers that are not located on the maps). Also note the possible best locations for placing the access points like ceiling tiles or pillars.
Evaluation of the Existing Network Infrastructure
Evaluate capacity of the existing wired networks – the backbone in which the access points will connect. This includes:
- Number of Ethernet switches
- Number and type of free ports on the switches (electrical, optical, PoE – power over Ethernet).
- Type and number of routers
- Data rate capacity of the routers
Identify the Coverage Areas
Note on the map all areas that need to have the Wi-Fi signal. Also, you need to identify the places where the wireless coverage is not needed and also where you need to avoid the wireless coverage. The best way is to cover the site with the least number of access points, because the cost will be lower.
Choose the Preliminary Locations for the Access Points
Consider the best locations for placing the APs. Plan the overlapping between the APs – usually the best option is to have 25% of overlapping among adjacent APs. Keep in mind the channels of adjacent access points need to be far enough (the best is 5 channel differences).
Also, do not forget the mounting locations for the APs like and place for the UTP cables for the access points.
Verification of the AP Locations
After placing all the access points in preliminary locations, you need to perform the wireless site survey testing. Applications for the site survey have option to identify:
- Location of APs
- Data rates
- Signal strengths
- Signal quality
Monitor the readings in wireless site survey application and cover all needed locations. Consider the minimum needed SNR and the signal strength.
Based on all these results, reconsider the locations for the APs.
Document the AP locations
When you have optimal positions for all the APs, document them on the map. This is the last but also very important step in the wireless site survey.
Wireless Internet Card – Overview
Wireless internet card, also known as a wireless adapter, is a device that enables a wireless connection. You could also find a name wireless network interface controller or WNIC. It is built for desktop and laptop computers.
There are three types of the wireless interface cards:
- Wi-Fi Adapters
- Cellular Adapters
- Bluetooth Adapters
Wi-Fi Adapters
Wi-Fi adapters provide connectivity to the Wi-Fi network. You could use them for the following purposes:
- Adding wireless connectivity to desktop computers.
- Adding wireless connectivity to the old laptops without a built-in Wi-Fi card.
- Increasing the speed of wireless connection for the laptops by using a newer Wi-Fi adapter.
Usually they are for the desktop computers. All the laptops have the built-in Wi-Fi card for last few years. You could increase the speed of your Wi-Fi network by using new wireless internet cards that are working on higher data rate.
You can find Wi-Fi adapters in different variations:
- PCI wireless network card – for desktop (newer versions are PCIe)
- PCMCIA Wi-Fi adapter – for laptop
- USB wireless network adapter – for both laptop and desktop
Wi-Fi adapter can work in two modes:
- Ad-hoc mode
- Infrastructure mode
Wi-Fi Adapter in an Infrastructure Mode
When Wi-Fi adapter runs in the infrastructure mode, wireless access point or wireless router should be present in the Wi-Fi network. Transfer of all packets between wireless interface cards is going via the access point or the wireless router.
Wi-Fi Adapter in an Ad-Hoc Mode
In the ad-hoc mode, there is no need for an access point. Data traffic goes directly from one Wi-Fi adapter to another. All devices need to have the same channel and SSID.
Cellular Adapters
This type of wireless internet card provides 3G and 4G wireless internet connection to your computers. They are mostly used on laptop computers, but they can also work for desktop.
Cellular adapter can be in two different versions:
- USB cellular adapter
- PCMCIA cellular adapter
Bluetooth Adapters
Bluetooth adapters provide short range wireless connectivity to laptop and desktop computers. Mostly they are used for wireless connection with the mouse, keyboard and smartphone.
Bluetooth adapters can be:
- USB Bluetooth adapter – for both laptops and desktop computers
- PCI Bluetooth adapter – for desktop computers
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