Wake Up Your Wi-Fi (Part 1)

7/1/2013 3:26:39 PM

We try to get everything everywhere

People love Wi-Fi. No need for cables or drilling, and you can wander around with your phone, tablet or caption with no trailing wires – brilliant!

Perhaps. Thanks to broadband ISPs, many houses these days have a router with a built-in wireless access point. Wireless networks are becoming ubiquitous these days, so much so that I can ‘see’ eight of them in my available network list on my tablet when at home, and I have at least another ten in the list that I have connected to at one time or another, in hotels, restaurants, pubs, motorway services, even hospital waiting rooms.

A simplified two-dimensional representation of the basic wireless field shape, showing possible ‘deal’ spots

A simplified two-dimensional representation of the basic wireless field shape, showing possible ‘deal’ spots

 Of course, the growth of wireless networking has many implications, which include coverage, interference and privacy concerns, but with a little careful planning, you can achieve a reliable wireless environment.

The Need for speed

As a rough guide, the recommended minimum for streaming standard-definition video is 2.5 Mbps and 10Mbps for HD (1080p), although buffering and compression can both ameliorate this. If your broadband is not up to this, you may still be able to stream video from a local server.


The most important thing before deploying any wireless solution is a site survey. Draw a layout of your house with the most important areas highlighted. For example, coverage in eh bathroom or the hall may not be important, whereas you probably want a good signal in the main living area and possibly the bedrooms or home office. The sitting of access points is important, although it may be limited by where the internet connection enters the house. Ideally it should be near the center of the building, with as clear a line as possible between it and any devices connected to it. Whatever you do, don’t put it in a cupboard (and yes, I have seen this). What we are looking at here is making sure that you get the best possible wireless experience within your own demesne. Place your AP at a potential deployment location, preferably as centrally as possible, and then walk around the house with a wireless sniffer.

A wireless survey in progress

A wireless survey in progress

Depending on what devices you have available, there are various options for this. There is discrete Wi-Fi strength meters available, although they are an expensive purchase for a single survey. A Wi-Fi capable smartphone or tablet is a good option, although at a pinch you could use a netbook or even laptop.

For phones or tables, there are many Wi-Fi survey apps. Wi-Fi analyzer, the Android app that I use, is quite a good site survey tool.

“The most important thing before deploying any wireless solution is a site survey”

There are more complex site survey apps such as WiTuners Wi-Fi Site Survey, which can be configured to show the layout of your house. There are similar apps available for other mobile operating systems.

Two screen-shots from Wi-Fi analyzer. Two of my Aps are visible (blue and red in the top image), and you can see that channel 1 is quite popular.

Two screen-shots from Wi-Fi analyzer. Two of my Aps are visible (blue and red in the top image), and you can see that channel 1 is quite popular.

With your weapon of choice, walk around the building reading the wireless signal-to-noise ratio and signal strength readings at each location in turn and noting the values on your site map. If you prefer, you can take screen-shots of the signal display. This will show you what kind of coverage area that one AP has at that point. If possible, try the AP in more than one location to determine the best signal spread. The AP does not need to have an internet connection for the site survey. Do this for all potential locations and then adjust the placement of APs based on your results. Remember to test on all floors as well, since the wireless signal is not confined to one floor and may provide adequate coverage in floors above and below.

If using repeaters, you must also be aware that any signal strength or speed measurements will only reflect the connection between your device and whichever AP it is actually connected to, not the overall speed of the connection to the main router. To measure the overall speed, you will need to use an internet speed test app. I tried three of these, and the results varied, maybe due to different testing methods, but they give you a rough guide as to the overall internet connection speed for a particular device, which may be surprising. For example, despite having a 20Mbps download speed, (when measured on an Ethernet connected PC), I found that dropped to around 10Mbps on both our wireless tablets and phones, even though they showed a wireless connection speed of up to 65Mbps.

Another useful Android app is Ping and DNS from Ulf Diffmer, which allows you to do various network tests that can give you, can idea of latency and packet loss between your device and the router

“Walls and floors are not helpful in the Wi-Fi world”

Routers, Access Points and Repeaters.

Wireless routers come in various forms, but they are basically wireless access points with the ability to connect one network to another and manage the traffic in either direction. They are usually used to connect a home network to the internet. Some incorporate ADSL or cable modems, others connect to a modem via an Ethernet cable. All offer networks address translation and firewall functions, and many include a multi-port Ethernet switch. Some also have USB ports for connecting storage or a printer. The quality of Wi-Fi routers supplied by most ISPs is variable to say the least, and you may get better results by upgrading to a better-quality unit.

Wireless repeaters or extenders are basically wireless Aps with some extra modes. In fact, many wireless routers and access points can also function as repeaters, so if you have an unused device, it may be possible to employ it as a repeater. Sometimes they are referred to as wireless bridges.

Repeaters can also be connected as an extra AP via an Ethernet cable, and there are Powerline variants. A wired connection to a repeater is preferable; as it gives you added bandwidth. When one is connected wirelessly, it simply receivers the wireless signal and amplifies it. As all devices connected to it will have to share the bandwidth between the repeater and the main AP, this will inevitably lead to lower data rates.

Two typical 802.11n routers

Two typical 802.11n routers

Some Aps have a two-band mode, where they send on one frequency and receive on another, but this requires dual-band hardware at both ends.

Wireless Standards

There are several wireless standards, and most recent equipment will support more than one.

802.11a operates in the 5GHz band, with a maximum speed of 54Mbps. It has a shorter range than 802.11b.

802.11b has a maximum speed of 11Mbps and operates in the 2.4GHz range, giving it a wider range than 802.11a. 802.11b devices suffer interference from other products operating in the 2.4GHz band including Bluetooth devices, wireless keyboards, microwave ovens, wireless phones and some amateur radio equipment.

802.11g works in the same 2.4GHz band as 802.11b, but uses a same transmission scheme as 802.11a. It operates at 54Mbps maximum, or about 22Mbps average. 802.11g devices are backwardly compatible with 802.11b devices, but an 802.11b participant will reduce the overall speed of an 802.11g network. 802.11g also suffers from interference in the 2.4GHz band.

If all your devices support dual-band 802.11n, disabling the legacy standards on the AP may improve your coverage and speeds. Setting 20MHz/40MHz will allow the router to do channel assessment, so if it detects a good noise free connection, it will use 40MHz wide channels for greater throughput. If the connection will not support 40MHz, it will drop back to 20MHz.

The future

As mentioned by Mark Pickavance’s article in issue 1253, two new standards are in development, and hardware is starting to appear, even though the standards are not yet ratified.

802.11ac is intended to provide higher speeds in the 5GHz band. This specification is planned to enable multi-station WLAN throughput of at least 1Gbps and a maximum single link throughput of 500Mbps.

802.11ad also known as WiGig, this is aimed at achieving a maximum speed of 7Gbps using the 60GHz band, but over much shorter distance than 802.11ac.

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