Recommendations for Wireless Networking Equipment
Everyone has their own preferences, and each manufacturer has its strengths and weaknesses. A personal preference is down to what you consider to be most important out of those.
Key Points
Unfortunately no manufacturer deals with all the points below, so there is no clear winner for every situation.
Receiver Sensitivity
An access point with 3dB more receive sensitivity will offer approaching twice the range or a better quality for a link in areas without too much interference. The sensitivity can vary by as much as 8dB between manufacturers.
Signal Strength / Signal to Noise Ratio Meters
Some suppliers give signal strength and quality in terms of a percentage, whilst this allows you to line up an aerial, the information it gives you is almost useless. The best are cards that give you a signal level in dB and a signal to noise level in dB so you can see what the real improvements are whilst experimenting with the installation. A strong signal is no use if you can't see how bad the noise is.
Link Diagnostics / Management
The radio link is one thing, but at the end of the day you need a link that passes data – so you need to know how good the link is, how many dropped packets were there, how many retransmissions were there and how much did that effect the throughput. These figures can allow you to spot interference that you may not see otherwise.
External Connectors
You can't do much to improve a link if you can't remove the connectors!
Real Throughput
Different manufacturers, even using the same basic chipset can have widely different real throughputs. The 11Mbs is not the achievable throughput. The real throughput can be between 2Mbs to 5Mbs for an 802.11b system according to manufacturer. Read a review that compares the throughput of different suppliers' equipment.
Compatibility Between Manufacturers
Whilst most systems will interoperate (the Wifi certified mark indicates they should interoperate on some level), the performance actually achieved when mixing manufacturers can be disappointing. Stick to one manufacturer for cards and access points or dig for more information on what cards work best with which access points.
Bridges and Access Points
Variable Output Power
To make the best links, the golden rule is the best aerial you can with the least power. Being able to change the output power can allow links 4 to 5 times as long as a fixed power output device whilst still meeting the legal limits.
Available Modes
Does the unit support point to point bridging, point to multipoint bridging or repeater functionality? Work out which facilities you need and check that the unit provides them.
Power over Ethernet
Can the unit be powered over the Ethernet cable? Remember that the aerial cable should be as short as possible so the access point or bridge needs to be close to the aerial – if so you may want to feed the power through the Ethernet cable to save having to run a separate supply.
Remote Configuration
You often need to set up the other end of a link over the wireless network – make sure the unit supports that functionality.
Security
Encryption strength, support for radius authentication, mac address filtering, ability to hide the SSID, weak key avoidance – work out what you need and check the unit can do this.
Multi Standard
802.11b/a/g which ones do you need? Does the fact it supports more than one mode compromise its efficiency with another? One well known multi-standard access points 802.11a performance is so poor it is virtually unusable.
Hidden Nodes
If the system is going to be used where a number of the clients cannot see each other, choose an access point that has facilities to cope with the problem. Some suppliers use enhanced rts/cts systems, but if this really is an issue consider buying equipment that supports the Karlnet Turbocell extensions which as well as alleviating the problem can offer significantly better throughput.
WDS
Can a unit be used as a repeater? If it can, does it actually allow you to use it as a bridge at the same time?
Desktop Cards
All of the above plus what connector does it use? A very weak link in the chain is the tiny connectors some equipment uses which are very prone to failure. Try to get a card with a connector at least SMA sized. Also check whether there are any compatibility problems. Some card carriers will not work with certain graphics cards and motherboard chipsets – read the manufacturer's technical support section before buying.
Laptop Cards
Receive sensitivity and operating system compatibility are the key points here – and always check that it can take an external aerial. A small indoor aerial can dramatically increase the range of the card.
Encryption should be at least 128bits – cards advertised as 'silver' are typically 64 bit and 'gold' are 128 bit.
Cables
We only use times microwave cables as they give the lowest loss per meter for the given diameter. Where the cables have to be unobtrusive or fit into a medium connector such as the SMA connector, use a good cable which is about 5-6mm diameter. Then if the cable run needs to be longer than 20 feet, use an adapter to change to a larger low loss cable. For general purpose use where size isn't an issue, Iuse a 10mm diameter cable. If there has to be a very long run (>60 feet) use a helical cable – which are horrible to work with though! See the aerials connectors and cables page for comparisons on given cables.
Adapters
Since all equipment has to come with proprietary connectors which are not available to the general public, put an adapter straight onto the equipment, preferably a solid adapter but quite commonly on a small lead to an N type cable – commonly known as a 'pigtail'. The N type connector is the standard R.F. connector used on most aerials and therefore is the easiest to get hold of link leads for. Make sure that you buy an adapter that is pre-made and tested. The loss on a poor quality pigtail can be quite massive.
