Frequently Asked Questions (FAQ)
In this Wireless Networking FAQ section you will find an exhaustive selection of the questions that we are most frequently asked. Please use our FAQ by navigating to the section most relevant to your query by clicking on the respective heading in the contents list. Hopefully you can find an answer to your query by using the article below, but if not, feel free to contact us as we are only too happy to help.
Contents:
1. General Queries
What is the difference between Point-to-Point and Point-to Multipoint?
Point-to-Point links act as a wireless bridge between only 2 devices to share internet or LAN connections whereas Point-to-Multipoint links allow the devices to communicate with multiple devices simultaneously so that many subscriber units can talk to a point of access. For more information, please refer to our "Brief Guide to Wireless Networking Solutions".
Top
How Many Computers Can Share a Wi-Fi Network?
Most wireless access points and routers will support up to 225 computers or devices to be connected, however, this is not recommended as network performance will suffer and it is much more advisable to install multiple access points to distribute the network load.
Top
Can Two Routers Be Used on the Same Home Network?
Technically yes, it can be done to create a hybrid network, increase coverage area or for traffic isolation but certain steps need to be carried out to implement this. Make sure client mode is enabled on your 2nd wireless router (must have client mode available), make sure the 2nd router's IP address falls within the 1st routers IP range and does not conflict and lastly, disable DHCP and assign IP addresses for all your devices manually to avoid assignment conflicts between routers.
Top
What Are the Limitations of Wi-Fi Ad-Hoc Mode Networking?
Ad-Hoc offers minimal security against incoming connections, signal strength indications are not available and maximum bandwidths are limited to 11Mbps.
Top
Do Wireless Routers Support Hybrid Networks (allow wireless and wired connections)?
Nearly all current routers do but some older models may not. A good indication of support capabilities can be found by the appearance of the following specifications on the device: 10/100/1000 Ethernet Ports, N-Port Ethernet Switch (N = Number) or Wired LAN Ports.
Top
Are Wireless Networks a Health Hazard?
A lot of wireless networking devices transmit on the same frequencies as Microwave Ovens so you may think so, however, the transmission power levels are so low that the thought that they might be harmful is currently mere speculation, with mobile phones being a much greater potential health hazard.
Top
How do I setup a building to building link between 2 locations?
Before you start, consider the following questions:
- How do I want to link the buildings/devices?
- How far apart are the two locations?
- What level of equipment do I want to use?
- Do I have a clear Line-of-Sight?
If you are trying to connect 2 locations wirelessly, you will need 2 wireless Point-to-Point Bridges or Access Points, you may need 2 high gain antennas and 2 sets of extended coax cable. You could also need lightning arrestors if the antennas are to be mounted on the roof and 4 PoE injectors if looking to power the devices over Ethernet cable. This type of setup is known as a bridge kit, and could connect two locations up to many miles apart depending on the device used. If you don"t know how you want to connect your Wireless Network, please refer to our "Brief Guide to Wireless Networking Solutions" articles. If you know how and what you want to use, please refer to our "Technical Discussion" section for more information on how to calculate whether your link will be successful.
Top
How Can I Set Up a Long-Range Link?
A longer range link uses identical concepts of deployment as any other Point-to-Point or Point-to-Multipoint links but typically require higher antenna gains to reach the receiver with acceptable signal strength. See "How do I setup a building to building link between 2 locations?"
Top
Will My Cordless Telephone Interfere With My Wireless LAN?
On a 2.4GHz network, avoid 2.4GHz DECT phones and on a 5GHz Network avoid 5.8GHz DECT phones. The DECT 6.0 phones that operate on 1.9GHz are a great choice to avoid interference as are the old 900MHz cordless phones. Some DECT phones have integrated technology to avoid interfering with Wireless Networks but make sure you check before you purchase as not all do.
Top
Can I setup a wireless network without a wireless router or an Access Point?
Yes, by adding wireless networking cards and setting up a network in Ad-Hoc mode but the performance will be seriously restricted and will be vulnerable to attack. We really do not recommend it.
Top
Can two Access Points communicate with each other?
Some newer Access Points can operate in "Bridging Mode" which allows them to communicate offering Access Point to Access Point communication (effectively creating a Wireless Mesh network).
Top
What do the different wireless modes of my router/AP mean?
Most wireless routers operate as an access point for clients but some add other wireless modes that can be used to extend the range, introduce multiple router/access points to the network, or bridge network segments together. Below is a summary of the different modes and their meaning:
- AP mode: This is the default, most common mode for all wireless routers, also called Infrastructure mode. Your router acts as a central connection point, which wireless clients can connect to.
- Client mode: The radio interface is used to connect the internet-facing side of the router (i.e., the WAN) as a client to a remote access point. NAT or routing are performed between WAN and LAN, like in "normal" gateway or router mode. Use this mode if your internet connection is provided by a remote access point, and you want to connect a sub network of your own to it.
- Client Bridged mode: The radio interface is used to connect the LAN side of the router to a remote access point. The LAN and the remote AP will be in the same sub network (This is called a "bridge" between two network segments). The WAN side of the router is unused and can be disabled. Use this mode to make the router act as a "WLAN adapter" for a device connected to one of its LAN Ethernet ports.
- Repeater: In general, a repeater simply regenerates a network signal in order to extend the range of the existing network infrastructure. A WLAN repeater does not physically connect by wire to any part of the network. Instead, it receives radio signals from an access point, end user device, or another repeater and retransmits the frames. This makes it possible for a repeater located in between an access point and distant user to act as a relay for frames travelling back and forth between the user and the access point.
- Repeater Bridge: A wireless bridge connects two LAN segments with a wireless link. The two segments are in the same sub network and look like two Ethernet switches connected by a cable to all computers on the sub network. Since the computers are on the same sub network, broadcasts reach all machines. DHCP clients in one segment can get their addresses from a DHCP server in the other segment.
- Ad-Hoc mode: This is for peer to peer wireless connections. Clients running in Ad-Hoc mode can connect to each other as required without involving central access points.
Top
What is the difference between an Access Point and a Wireless Router?
An Access Point is a radio transmitter and receiver that is most widely used to bridge wireless and a wired network. An access point may only provide an interface or portal for wireless clients to connect to your existing LAN. A wired router has additional functions; it allows multiple clients to connect to the Internet by serving internal IP addresses, has NAT capabilities and often a built-in switch as well. It 'routes' traffic between two different networks, usually the Internet on the WAN side, and your local area network on the LAN side. A Wireless router, however, has both the functionalities of a router and an access point in a single unit.
Top
Wireless Access Points - same SSID different channels?
When deploying a wireless network with multiple access points, the preferred practice is to set them to the same SSID but use different channels for overlapping APs to reduce interference with each other. It is also helpful to set each AP to a different static IP so they can be administered separately, and set the DHCP server behind all the APs. All APs should use the same type of security and shared key and along with setting all them all to use the same SSID it should also help with setting up roaming (switching between access points seamlessly).
Top
Wireless Bridge vs. Access Point?
In general, a wireless bridge is a device which allows for a wireless connection between two separated wired networks. A wireless LAN bridge can interface an Ethernet network directly to a particular access point. This may be necessary if you have a few devices, possibly in a far reaching part of the facility, that are interconnected via Ethernet. A wireless LAN bridge plugs into this Ethernet network and communicates with an access point within range. In this manner, a bridge enables you to wirelessly connect a cluster of users to an access point. Access points connect multiple wireless clients to each other and to a wired network. A non-bridging access point will allow association of wireless users, but will generally not allow you to connect to a remote wired network, or to another wireless access point. Some access points can also do WDS which can connect to other access points at the same time as client radios. WDS is effectively a store and forward repeater between access points.
Top
How do you find a public Hotspot?
Most businesses, colleges, hotels, restaurants, coffee shops, airports, marinas, libraries and wireless service providers publically advertised their hotspots. There are also many websites available to visit that will guide you for help in finding these hotspots.
Top
How can I place the Access Point near the antenna if there is no power outlet?
If your antenna mounted in an accessible place for mains connection i.e. on the roof, and your access point is located where you would need many meters of co-axial cable to connect to it, then you can use a Power over Ethernet adapter/injector, or PoE. Running meters and meters of antenna cable will be expensive and could generate a lot of signal loss that would performance. The PoE adapter will allow you to place the wireless device closer to the antenna and allow for a shorter run of antenna cable. This usually results in mounting the device in the just under the roof or outside, alongside the antenna where there is no power. The PoE adapter will power the device through the Ethernet cable, and eliminate the need for a long extension cord. Typical Ethernet cable can be run up to many meters, without losing any significant amount of signal.
Top
How do I determine which Networking Solution is right for me?
Every Wireless Networking Solution will perform differently for each application so no generic answer can apply here. We would like to refer you to our "Solutions & Support" section where you will find articles that can help you understand and determine the best equipment for your intended application. If you need further assistance, please do not hesitate to contact us.
Top
2. Wireless Networking Performance
How do I check how much power I am transmitting?
The output power or transmission power of your device should be listed, if it is not please contact us and we will be happy to help you. For Effective Radiated Power see, “E.I.R.P (Effective Isotropically Radiated Power)”.
Top
What distances can be achieved?
This rather ambiguous question is probably the most commonly asked when discussing Wireless Networking. Range depends on many factors from the equipment used, the local environment and the performance required. For more information on how to calculate the permissible distances for your network, please refer to our “Factors Affecting Wireless Networking Performance”, “Fresnel Zones” and “Path Loss, Link Budget & System Operating Margin” articles.
Top
How do I calculate the transmit gain?
Transmit Gain is the sum of the devices transmit power and antenna gain. See “Gain (Antenna)” & “E.I.R.P (Effective Isotropically Radiated Power)”.
Top
How do I calculate Free Space Loss?
Free Space Loss is the attenuation of signal path or the drop in the density of power of the wireless transmission’s wave as it propagates (travels) through a medium over a distance. For more information on calculating Free Space Loss, please refer to our “Path Loss, Link Budget & System Operating MarginPath Loss, Link Budget & System Operating Margins” article.
Top
How do I calculate Radiated Power?
See “E.I.R.P (Effective Isotropically Radiated Power)”.
Top
How do I calculate System Operating Margin?
System Operating Margin is a way of calculating the difference between the signal strength the receiver’s radios are actually receiving as opposed to what it needs for good data recovery. This is calculated by subtracting the receiver sensitivity value (dB) from the Link Budget. For more information on calculating SOM, please refer to our “Path Loss, Link Budget & System Operating Margins” article.
Top
How Can I Get 300Mbps Speed on My 802.11n Network?
To run at maximum speed an 802.11n network must be linked and operating in channel bonding mode. This utilises two adjacent channels simultaneously to double the bandwidth of the wireless link to achieve a theoretical bandwidth of 300Mbps. Without it, slightly more than 50% of this bandwidth is lost and will operate around 130-150Mbps. Channel bonding substantially increases the risk of interfering with nearby Wi-Fi networks due to the increased spectrum and power it consumes.
Top
How fast can I actually transfer data over my wireless network?
This depends on many factors including: the strength and clarity of the wireless signals, the interference caused by other wireless devices that share the same radio frequencies as the wireless network, the activity of other devices connected to the network, the efficiency of the transfer protocol that you are using, the output speed of the device from which you are receiving the file from, other activity on your local computer or the sending computer and other factors. As a general rule, you can probably expect to realistically achieve a throughput rate of about a third of the maximum specified data rate when receiving a good connection. If you are connecting through any repeaters or performing multiple hops, you can expect the throughput to reduce by half again for every extra device added in the chain.
Top
Can I use a 2nd AP to extend my range?
If using an external antenna to increase signal gain is not desirable or possible, you can set up a 2nd AP to operate in Bridging Mode. Some newer Access Points can operate in “Bridging Mode” which allows them to communicate offering Access Point to Access Point communication (effectively creating a Wireless Mesh network).
Top
I have 2 antennas on my single radio device; can I set 1 to transmit & the other to receive?
This will not give you Full Duplex speeds as the antennas are still connected to a single Half Duplex radio and you will also lose the antenna’s ability to use the Diversity technique. Doing this is not recommended.
Top
Why is my wireless connection so slow?
First of all, speeds are often measured on your computer in Bytes per second rather than the Bits per second advertised as the devices maximum data rate. Byte per second speeds are equal to 8 times less than Bit per second rates so a 100Mbps (Megabits per second) rate will be equal to 12.5 MBps (Megabytes per second); so make sure you are not confusing the two. Secondly, the full advertised data rates are theoretical maximum speeds and are not realistically achievable. You can expect to achieve around a third of the maximum advertised data rate with a good connection. If you’re network speeds are still slow after factoring these points in you can troubleshoot the following areas. Firstly, try to locate any wireless devices that may be causing interference with your network and switch to a different channel or operating frequency to avoid this. Secondly, if you are operating on a networking standard i.e. 802.11, make sure all your network devices are operating on a standard that is compatible with the maximum required data rates. You can also make sure you are using WPA encryption over WEP as this can increase throughput by as much as 10%. Lastly, make sure that the signal strength being received is of a high enough standard to achieve a high throughput. If your signal is weak, speeds will inherently be low as the retransmission of lost data packets will occur and slow down throughput.
Top
How Can I Boost My Range?
First of all, detect whether your received signal within the transmitter's advertised range is low. If so, to try and increase the signal strength received you can try to change the locations of the two devices, adjust the antenna's orientation on either or both the transmitter and receiver and, finally, see whether there is a considerable amount of interference on your operating channel or frequency and change it accordingly. If none of these are the case and you are receiving a strong signal within the maximum advertised range and simply want to increase your network coverage area you could, if possible, attach an external, high gain antenna to intensify the radiated signal into a smaller but further area and also ensure that your devices are operating at their maximum, legal operating power levels. If these measures have already been taken, the only other options are to use a repeater or connect a 2nd AP to extend the network coverage or invest in new, long range capable equipment.
Top
What factors impact Wireless Networking performance?
For a full explanation of what affects wireless networking performance, please refer to our “Factors Affecting Wireless Networking Performance” article.
Top
What is the typical range of a WLAN?
This mainly depends on the Access Point or Router used, the transmit power and antenna's receiver sensitivity, the local environment and the protocol being used. Typically you could expect 802.11n networks to have ranges up to 100m indoors and 250m outdoors (these figures are at the top ends of the ranges seen in application). Obstructions such as concrete walls can play havoc with your signal almost blocking it completely so it may be necessary to connect multiple Access Points or use Repeaters to achieve the coverage area required. Please refer to the FAQ Question, “What distances can be achieved?”
Top
How much faster is 802.11n compared to older standards?
The fastest data rates of older standards peaked at 54Mbps per data stream whereas 802.11n can operate at 150Mbps per data stream currently with the ability to operate on as many as 4 streams in some of the newest, top end devices. As you can see there is a considerable performance increase. For more information please refer to our “Introduction to 802.11 (Wi-Fi) Technology” article.
Top
Do I absolutely need Line-of-Sight between my two locations?
We always recommend that you try to achieve Line-of-Sight connections as they will perform at a significantly higher level. If you cannot achieve a LoS, you can look into using equipment that can operate under nLoS or even NLoS conditions that use antennas with a multi-polarisation radiation pattern that allows them to send signals through semi-obstructers such as trees. If you specifically need an nLoS or NLoS link, feel free to contact us and we will be happy to help you achieve a solution that meets your required performance levels.
Top
What is the benefit of using higher transmit power access points?
High transmit power access points allow you to use low gain, low directional antennas such as omnidirectional antennas whilst still transmitting a strong signal. This can give you a large coverage area and still provide good signal quality especially useful in public areas where you intend to serve a lot of devices with an Access Point. Also, the higher the transmit power (within regulations) the stronger the signal will be and therefore signal strength will be increased.
Top
3. Operating Frequencies & Wireless Networking Standards
How many channels does my 802.11 standard support and what are the frequencies that it operates on?
The different Wi-Fi standards have certain regulations that must be met for legal operation. For more information on Channels and Operating Frequencies, please refer to our “References Section” article.
Top
Are my two different 802.11 standards compatible?
802.11b, g and n will work together and are backwards compatible as are 802.11a and n with each other. However, the newer equipment will restrict its performance down to the oldest standard which can result in network throughput being seriously throttled back. We recommend that if you want to experience the benefits of using 802.11n devices, you ensure that all devices operating on that network use 802.11 also.
Top
Is it possible to mix wireless devices from different manufactures?
As long as the equipment operates on the same frequency and conforms to the same operating standards then the devices should be interoperable. There may be some restrictions applied when devices must operate on a certain Operating System (OS) so it is worth checking to ensure that the devices are compatible.
Top
What channel should I choose for my wireless network?
This is mainly an issue with 2.4GHz networks so this answer will be tailored around the operation of 2.4GHz operation. For best performance with the least interference you should operate your device on a channel at least 5 channels away from neighbouring networks. Although 802.11b, g and n devices are designed to share the airwaves with neighbouring networks, it is best to find a clear channel for several reasons, these include: when a neighbouring network is experiencing high usage, there is less available bandwidth on those frequencies for your data, reducing your performance and your wireless device may suffer from degraded performance due to collisions with the neighbouring network's wireless signal. In order to find a completely clear channel you need to ensure that you operate on a channel that is 5 or more channel numbers away any networks in the local area. This many not always possible but try to choose one as far away as possible. Spectrum Analysers can help to detect neighbouring networks operating channels. Channels 1, 6 and 11 are recommended for 2.4GHz operation to avoid the overlapping of channel usage whereas all channels for 5GHz operation are non-overlapping. For more information on Channels, please refer to our "References Section" article.
Top
Is 5GHz Wireless better than 2.4GHz?
Wi-Fi Networking equipment typically uses radio signals in either a 2.4 GHz range or a 5 GHz range. The GHz range of a wireless radio is only partially related to the speed of a wireless network, for example, 802.11a operates at 5GHz and 802.11g at 2.4GHz but both support the same maximum data rate of 54 Mbps. However, newer 802.11n routers have the capability of simultaneous dual-band operation on both 5GHz and 2.4GHz ranges, allowing clients to connect on different bands for more flexibility and less interference.
Advantages of 5GHz: The 5GHz band is less likely to be congested. The 2.4GHz frequency range is much more prone to interference, as it is commonly used by other wireless networks in the area, as well as cordless phones, garage door openers and other home appliances and consumer products. It has better nLoS capabilities allowing it to perform much better in some complex indoor environments and link range can be further due to much higher, regulated transmit power levels relative to 2.4GHz.
Advantages of 2.4GHz: Technically, the higher the frequency of a wireless signal, the shorter its range so 2.4GHz networks should cover a substantially larger range than 5GHz wireless networks especially seeing as the higher frequency wireless signals of 5GHz networks do not penetrate solid objects nearly as well as 2.4GHz signals. However, as explained above 5GHz does overcome these problems through regulation differences and other characteristics but sometimes 2.4GHz performs better in some locations.
Conclusion: 5GHz and 2.4GHz are simply different frequencies, each with its advantages and disadvantages. To get the best of both worlds, some recent routers have the capability for dual-band operation in both ranges simultaneously. For more information on 2.4GHz and 5GHz, please refer to our "Introduction to 2.4GHz Technology" and "Introduction to 5GHz Technology" to understand the differences between the two.
Top
How do Wi-Fi and WiMAX relate?
Wi-Fi and WiMAX are complementary technologies for their respective applications. Wi-Fi technology was designed and optimized for LAN, whereas WiMAX was designed and optimized for Metropolitan Area Networks. WiMAX is not a replacement for Wi-Fi but rather it complements it by extending the reach and providing a user experience much like Wi-Fi on a much larger geographical scale. Wi-Fi is distributed by wireless networking devices connected to a LAN whereas WiMAX is distributed by large tower masts operating on the cellular network for 3G/4G devices.
Top
What is Dual Band Wireless Networking?
Dual band refers to the capability to transmit on two operating frequencies, typically the 2.4GHz and 5GHz bands, simultaneously by using two different types of wireless radios. By supplying separate network bandwidth for each of the two frequencies, these devices provide maximum flexibility in setting up a wireless network, for example, older 802.11b/g clients can be set to run on the 2.4 GHz side of a simultaneous dual-band device without impacting the performance of 802.11n clients running at 5 GHz.
Top
What is new in the 802.11n wireless standard?
There are three main improvements for 802.11n, these include: MIMO Spatial Division Multiplexing (SDM) which allows for the transference of multiple, independent data streams simultaneously using multiple antennas at both the transmitter and receiver to help increase throughput, channel bonding that lets users combine two sub-frequencies for better performance and reliability and packet aggregation that reduces the amount of overhead data needed to transfer files, allowing more room in the stream for actual data.
Top
Which 802.11 standard is better?
With regards the 4 main, popular standards (802.11a, b, g and n) 802.11n wins hands down, however there may be a more suitable, and specialist standard for your application that is not widely used. For more information please refer to our “Introduction to 802.11 (Wi-Fi) Technology” article.
Top
4. Wireless Networking Hardware & Antennas
What different types of antenna are available?
There are different types of antenna that give different effects regarding the radiation of the signal. Antenna types include dish, flat panel, grid, helical, omnidirectional, patch, sector and yagi. For more information, please refer to our “Antenna Information and Mounting Guide”.
Top
Which type of antenna do I use in which situation?
There are many different types of antenna and each type performs differently that can either give you a wide coverage area, give you very long link distances or help you overcome impeding obstacles. It is also important to remember that Wireless Networking links have two ends, a transmitter and a receiver and both should be taken into account when installing antennas to achieve the best results. For more information on antenna types and which can perform the best in certain situations, please refer to our "Antenna Information and Mounting Guide".
Top
What type of cable should I use for my antenna?
To connect your antenna to your Wireless Networking device you should use a Low Loss Co-Axial cable as these transmit RF signals without losing significant signal strength. For more information please refer to our “Wireless Networking Cables Guide”.
Top
What connectors are used to join antenna cables?
The following connectors are used with Wireless Networking cables (mostly Co-Axial cables): BNC, BNC RP, FME, MMCX, N, RJ45, SMA, SMA RP, TNC, TNC RP and also adaptors are used to connect cables with different connector types and also to turn a jack into a plug interface and vice-versa. The most commonly used for Coax are N, SMA, BNC, TNC and MMCX. For more information please refer to our “Wireless Networking Cables Guide”.
Top
What is Leaky Feeder?
A Leaky Feeder is similar to co-axial cable but designed to evenly distribute signal along the whole length of the cable acting as an antenna. It can be a useful substitute in buildings where a large amount of APs would be needed to provide maximum coverage where it can be routed between floors all around a building.
Top
If I can see another antenna, does that mean I have got 'Line of Sight?'
Not quite, a clear optical line of sight does not mean a clear line of sight for networking antennas. Wireless Networking signal needs an area around the direct path between devices to be clear in order to operate effectively; not just a clear optical line of sight. For more information, please refer to our "Fresnel Zones" article.
Top
What hardware is required to build a Wireless Network?
This really depends on your intended application and could range from a consumer wireless router and some USB dongles all the way up to a massive Point-to-Multipoint array with many subscriber units sending traffic down a backhaul link. For more information on different types of networking solutions, please refer to our “Brief Guide to Wireless Networking Solutions”.
Top
When comparing external antennas, what does dBi mean?
dBi means decibels relative to isotropic radiator and is a measurement of the gain of an antenna in a particular direction relative to an isotropic radiator (equal radiation in every direction). These are usually given for antennas designed to operate at frequencies greater than 1GHz where the larger the value stated, the greater the gain. A small omnidirectional (rubber ducky) antenna would have a low dBi rating as it sends the signal out in a large, donut shaped style whereas a very large dish antenna would have a high dBi rating as it intensifies all the signal down into a very narrow beam and can therefore transmit the signal further before it fades away. For more information, please refer to our "Antenna Information and Mounting Guide".
Top
Do I have to use the same brand external antenna with my wireless product?
In most cases, no. As long as the antenna you are using operates on the same frequency and has the same connector type as your Wireless Networking device then it should work with no trouble.
Top
Do I need high gain antennas on each end of my Bridge?
If you are intending to create a Wireless Network over a large distance then yes, this will be very crucial. It is important to remember that Wireless Networking links have two ends, a transmitter and a receiver and both should be taken into account when installing antennas to achieve the best results. For more information, please refer to our "Antenna Information and Mounting Guide".
Top
5. Explanations of Technical Terms
What is antenna gain?
Antenna gain is a value stated in dBi and is the ratio of the intensity of the radiation in a particular direction by the antenna compared to if it radiated the signal evenly in all directions. When an antenna receives or transmits signal, it is focused in a certain direction or plane and that reduction in coverage area, by intensifying it in a reduced area, is the gain. Even antennas that radiate in all directions on a specific plane, such as an omnidirectional antenna, have gain because they are reducing the signal transmission significantly on the vertical plane. For more information, please refer to our "Antenna Information and Mounting Guide".
Top
What is ad-hoc mode?
Ad-hoc is a mode in which devices connect and communicate directly with each other, similar to a LAN peer-to-peer connection, without the use of any access point. The most commonly networking mode is infrastructure mode.
Top
What is infrastructure mode?
Infrastructure mode is a legacy term used to describe a wireless network consisting of devices connected to a network using a centralized wireless access point. One of two types of wireless network modes; the other being ad hoc.
Top
What is bandwidth?
Bandwidth is the maximum data rate or transmission capacity supported by a network connection, interface or communications channel at any point in time. Bandwidth, measured in bits per second (bps), represents the maximum speed at which data information can be sent across network connections with the higher the capacity, the greater the speed the data can flow. Can also be known as “Maximum Throughput”.
Top
What is beamwidth?
Beamwidth is the representation the interior angle of the 3 points made up by the transmitter and the points either side of the main radiation lobe where the signal strength is half the power of the main lobe i.e. 3dB less.
Top
What is WDS?
WDS is a method of allowing administrators to wirelessly connect access points or Arrays together to form a chain; this is instead of using a wired uplink connection to the network where it is unavailable or costly to implement. It should be noted, however, that the throughput decreases substantially with every repeater added to the chain.
Top
What is a decibel?
A decibel (dB) is a standard unit for measuring wireless signals. It is a logarithmic number where doubling the strength level adds 3dB and halving subtracts 3dB.
Top
What is front to back ratio and is it important?
Front to back ratio is the ratio of the gain from the front of the antenna to the gain from the rear of the antenna. A directional antenna will nearly always radiate some signal out of the rear of the antenna so the Front-to-Back Ratio shows the efficiency of its forward radiation. A figure around 15dB should be the minimum of a good antenna with 20dB or above being acceptable. The higher the ratio, the more directionally efficient the antenna.
Top
What is a side lobe?
A side lobe refers to the secondary signal beams that appear either side of the main, principle beam.
Top
What is Near Line of Sight?
If there are some minor obstructions penetrating the Fresnel zone this would be considered as a near line of sight (nLoS) application. Most Wireless Networking Bridges will perform acceptably in nLoS scenarios but you will see some performance degradation depending on the number of obstacles and how deep they penetrate the Fresnel zone. Note that nLoS (Near Line of Sight) is not the same as NLoS (Non Line of Sight). NLoS occurs if you cannot see the other device from the other device’s location. Wireless Networking equipment does not perform well under these conditions but a weaker link may be just possible. If may be better to consider using a repeater that is offset from the main path to bypass the obstacle
Top
What is diversity?
Diversity is an antenna system that uses multiple antennas to reduce interference and maximise reception and transmission quality of out of phase signal due to multi-path refraction and reflection.
Top
What is Power over Ethernet?
Power-over-Ethernet can be used to supply power to wireless networking devices which utilise the four spare cores in the eight core Ethernet cable to carry the power supply to the device. Normally this is done via a PoE injector at the end of the cable near the mains that connects to the LAN and also the low voltage power supply transformer, and another PoE injector at the other end to work in reverse supplying splitting the power supply from the data stream to power the device and the forward the data transmission. Voltage levels can drop when using Ethernet cable in this way so various PoE injector ratings are available such as 12V, 24V and 48V but care must be taken as to not damage equipment as some devices will be damage if over-powered. For more information, please refer to our "Power over Ethernet Guide" article.
Top
What is the relationship between dBm and milliwatts?
To view a conversion table and equations to calculate the relationships between Decibels and Milliwatts, please refer to our “References Section” article.
Top
What's the difference between a bit and a byte?
A bit is a Binary Digit and is represented by either a 0 or a 1. These when in a series of digits can be translated into readable data. A byte contains 8 bits and so a byte has a capacity of 8 times larger than a bit. A kilobit is 1000 bits, a megabit is 1000 kilobits and a gigabit is 1000 megabits. Due to a byte being 8 times larger than a bit, bit rates appear to be larger than byte rates, for example, a bit rate of 8Mbps (Megabits per second) is the same as a byte rate of 1MBps (Megabyte per second).
Top
What is Preamble type, when do I need to change it?
The Preamble type defines the length of the CRC (Cyclic Redundancy Check) block for communication between the Access Point and roaming wireless devices. CRC is a common technique for detecting data transmission errors. If your wireless devices are not using the same preamble type they will have problems communicating. The recommended solution is setting all network devices to the same type to avoid compatibility and therefore performance issues.
Top
What is an Access Point?
An Access Point is a transceiver that connects users wirelessly to a local area network such as a WLAN or a fixed wire network via an Ethernet connection. Mobile users can connect to an Access Point within a defined range with the AP sending and receiving data within that area. Sometimes referred to as a "Base Station".
Top
What's a HotSpot?
A HotSpot is a location where Wi-Fi network access (usually Internet access) is made publicly available, often found in airports, hotels, coffee shops, and other places where business people tend to congregate. Hotspots are considered a valuable productivity tool for business travellers and other frequent users of network services. Technically speaking, hotspots consist of one or several wireless access points installed inside buildings and/or adjoining outdoor areas where these APs are typically networked to printers and/or a shared high-speed Internet connection. Some hotspots require special application software be installed on the Wi-Fi client, primarily for billing and security purposes.
Top
What is a WISP?
A WISP is a Wireless Internet Service Provider that offers public wireless network services. WISPs typically install Wi-Fi HotSpots in airports, hotels and other public business places. These HotSpots can provide Internet access and local area network (LAN) printing for mobile network devices like laptops, handheld computer and mobile phones
Top
What is a Bridge Kit?
A Bridge Kit usually consists of 2 wireless Point-to-Point Bridging devices, 2 high gain antennas and 2 sets of coax cable. You could also need lightning arrestors if the antennas are to be mounted outside and 4 PoE injectors if looking to power the devices over Ethernet cable. This type of setup is known as a bridge kit because of the effective wireless bridge it creates between two networks and could connect two locations many miles apart depending on the device used.
Top
6. Network Security
What happens when I disable SSID Broadcast?
You can disable your SSID broadcasting to the average person but it is a mandatory field within the send beacon of a wireless broadcaster and so therefore can never be stopped completely. Therefore if someone is persistent or knowledgeable enough to try and hack into your network, they can find the SSID very easily. However, knowing the SSID of a network doesnt really help gaining permission to use it so the feature to turn off your SSID from broadcasting publically is pretty useless.
Top
How Can I Tell If Someone Is Using My Connection?
If you suspect that someone is connecting to your network without your authority, there are various wireless intrusion detection software programs available for download that use techniques to display who or what is connected, for example, some work by reporting the existence of non-approved devices as identified by MAC address such as AirSnare. If someone is using your network connection without permission, you should increase your security measures to stop them from connecting.
Top
Why do I need security in my Wi-Fi Networks?
Wireless Networking has the inherent security risk that you are broadcasting your data through the air, wirelessly, and could therefore be intercepted in a similar fashion to signals from a mobile phone. Because of this, it is essential that you ensure that your network is secure and protected to avoid unauthorised users gaining access to your network who could examine e-mails, files and records or use your internet connection illegally. The required security level of your wireless network will probably depend on your application with confidential data requiring additional layers of security. For low level security, encryption methods such as WPA can suffice but at an Enterprise scale dealing with delicate information, further technologies can be employed to really enhance protection.
Top
What is IPSEC?
IPSec (IP Security) protocols provide mechanisms for establishing security associations between pairs of devices. IPSec may be used to establish private end-to-end communications between pairs of computers so that an additional layer of security is imposed above and beyond whatever wireless networking controls may be in place. This mechanism is quite similar to those used in VPNs in which additional security is used to make connections across inherently unsecure links.
Top
What steps can be taken to secure myself at Public Hotspots?
There are a number of steps that should be taken while on public wireless networks, or wireless networks that you don't control, to try to enhance the absolute security of your network traffic. These include: using a VPN, ensuring you are browsing with SSL certificates when working with sensitive information i.e. E-Mail and also make sure you have high performing Firewall software to block any unauthorised, incoming connections to your device.
Top
What is WEP?
WEP is a security function that offers frame transmission privacy similar to a wired network. The Wired Equivalent Privacy generates secret shared encryption keys that both source and destination stations can use to alter frame bits to avoid disclosure to eavesdroppers. WEP is now considered to be a very weak, largely ineffective security tool for wireless LANs as there are many exploits and vulnerabilities that have allowed hackers to easily gain access.
Top
What is WPA-PSK?
WPA is a stronger security technology for Wi-Fi networks than WEP and it provides strong data protection by using encryption as well as strong access controls and user authentication. WPA utilizes 128-bit encryption keys and dynamic session keys to ensure your wireless network's privacy and enterprise security. WPA-PSK is basically an authentication mechanism in which users provide some form of credentials to verify that they should be allowed access to a network. This requires a single password entered into each WLAN node (Access Points, Wireless Routers, client adapters, bridges). As long as the passwords match, a client will be granted access to a WLAN.
Top
What is TKIP?
WPA uses TKIP to improve data encryption as it dynamically changes keys as the system is used and provides a message integrity check and a re-keying mechanism, thus fixing the flaws of WEP. An important part of TKIP is that it changes the key used for each packet; which is the "temporal" part.
Top
What is AES?
AES is a block cipher encryption method that has very high levels of security. It is very hard to crack and is even used by the Governments to secure the most sensitive data transmissions.
Top
What is RADIUS?
RADIUS is a protocol for remote user authentication and accounting that enables centralised management of authentication data for terms such as usernames and passwords. When a user attempts to login to a RADIUS client the device sends the authentication request to the RADIUS server, which is usually a hard-wired machine on the network. The communication is authenticated and encrypted through the use of a shared secret, which is not transmitted. It consistently protects against a sniffing, active attacker where other remote authentication protocols provide intermittent, inadequate or non-existent protection.
Top
What is an SSID?
An SSID is the name of a wireless local area network (WLAN). All wireless devices on a WLAN must employ the same SSID in order to communicate with each other. The SSID on wireless clients can be set either manually, by entering the SSID into the client network settings, or automatically, by leaving the SSID unspecified or blank. A network administrator often uses a public SSID that is set on the access point and broadcast to all wireless devices in range.
Top
Does WEP/WPA slow down wireless connections?
Yes, in some cases quite significantly. WEP and WPA encryption add overhead in terms of the calculations needed to encrypt and decrypt the data traffic. The resulting throughput speeds can vary from around 95% to 50% of the maximum throughput. Newer wireless devices have faster processors and therefore enabling WPA should not have a noticeable impact on performance but WEP can be a prime suspect when it comes to low performance as its encryption adds a large amount of overhead slowing down your transfer rates. Even though there is some performance impact, it is not as noticeable in newer devices, and the benefits of having a good standard of encryption i.e. WPA-AES, far outweigh any drawbacks.
Top
WPA Personal vs. Enterprise?
WPA-Personal is a common method to secure wireless networks. In the Personal mode, a pre-shared key or passphrase is used for authentication and this pre-shared key is then dynamically sent between the AP and clients. WPA-Enterprise includes all of the features of WPA-Personal plus support for 802.1x and RADIUS authentication and is appropriate in those cases where a RADIUS server is deployed.
Top
WPA2 TKIP or AES encryption?
WPA uses TKIP encryption whereas WPA2 uses AES but can also use TKIP for backward-compatibility. If you set your device to use WPA2 you usually have the option to use AES or TKIP+AES. When your device is set to "WPA2 with TKIP+AES" it means that network devices that can use WPA2 will connect with WPA2 and network devices that can only use WPA will connect with WPA. The password for both WPA and WPA2 will be the same and this option allows users to easily transition from WPA to WPA2.
Top
7. Legality Issues & Guidance
How much power can I transmit and still be legal?
Ofcom and other Regulatory organisations state maximum effect power outputs for different frequency ranges and also for the application of the Wireless Network. For more information on regulations regarding transmission power levels, please refer to out “References Section” article.
Top
Where can I find out about the Regulations and Licensing?
Please visit our “References Section” article where you can find information and legal documents regarding the regulations and licensing of Wireless Networking equipment.
Top
Are there restrictions on what size dish I can put up?
Dish antenna sizes should not exceed 0.9m in the UK and should be mounted, if possible, on the least obtrusive side of the building. In general, you may install one antenna on a building without seeking planning permission. However, it is always best to verify your restrictions and allowances beforehand to avoid any issues further down the line.
Top
Is It Legal to Use Open Access Wi-Fi Internet Connections?
Yes for public Wi-Fi HotSpots as long as you have permission from the ISP and also adhere to their terms and conditions which may include time and location restrictions, bandwidth restrictions and also content restrictions. Using an unprotected private network to gain Internet access is almost always illegal as it violates ISP’s terms and conditions and also can be considered to be much like trespassing or breaking and entering.
Top
