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|Wi-Fi = wireless, access point = router
With the decline of Windows XP and especially of XP desktop computers,
folks are trading up to Windows 7 and Windows 8 laptops and the
mobility they provide. Laptops are mobile because they typically
include wi-fi adapters that are based on the IEEE 802.11 technology,
which allows two-way radio communication with internet transmitters,
called “routers” or “access points.” This communication is usually on
the first 11 channels in the 2.4 Gigahertz band. Wireless routers can
connect a group of wireless devices including other computers and
wireless printers. Desktop computers may have inexpensive wireless
adapters added to them.
Wi-fi routers, are relatively cheap and easy to set up and use with
cable and DSL modems, and so are found in many homes these days.
Verizon often supplies their DSL modems with wi-fi capability; if yours
has a little antenna, that's the type you got. Within a cozy indoor
setting, and within a range of 65 feet or more, a wi-fi laptop can be
taught to connect to that router every time it is started. In fact it
can remember all the routers used with it, and will connect
conveniently and automatically when started in range of any of them.
In any home network setting, the router should be centrally located
because signal strength weakens logarithmically with distance.
Computers equipped with wi-fi adapters come with wi-fi manager software
that shows a set of bars that illustrate the “Can you hear me now?”
signal strength of any potential access point, just like a cell phone.
When ranging too far, the bars get too few, and connecting and staying
connected becomes a problem.
Slow or intermittent connectivity in an area can be caused by competing
networks on the same or overlapping channels. This is because a wi-fi
signal occupies and overlaps five channels. If a router is set to
channel 6, for
example, it occupies channels 4, 5, 6, 7 AND 8. Because of this,
instead of 11 channels to use, there are really only three good
choices: 1, 6 and 11, and folks who choose the in-between channels
aren’t doing anyone any good. Networks in large apartment complexes and
office buildings with many routers are forced to share channels. Every
router with activity on a shared channel cooperates with neighboring
routers on the same channel and negotiates with them for opportunities
to transmit. This sharing, which slows performance for every connected
computer, is part of the technology. Overlapping channels are not
shared this way, but cause an even worse problem as they interfere with
one another and further slow performance.
Home networks are not alone in the 2.4 GHz band. Other devices in the
mix include microwave ovens, security cameras, cordless phones and baby
monitors. These use the same channels and they don't share at all, they
just interfere! A home network may also find itself in competition with
large-area access point coverage from municipalities, universities and
internet hotspot providers like Optimum.
In open air, radio wave signal strength is subject only to distance.
However, the different materials used in home building and the objects
we place in our homes all affect wi-fi use there. The more dense the
wall or object, the more signal strength drops. For this reason, it's a
good idea to place your router up, say on a high shelf or mounted on a
The signal strength meter:
Diagnosing wi-fi problems can be difficult using only the wi-fi manager
and the bars it shows. A better tool is “inSSIDer for Home,” published
by Metageek. The older Windows version of this free program works well
with XP, but the newer one, version 3, requires Vista and later
editions of Windows. The Macintosh version of inSSIDer costs $4.99 and
only works with OS X 10.7 and later. This tool makes it very easy to
measure wi-fi signal strength in decibels, the higher resolution units
that technicians use, and to compare your signal's channel and strength
against those of your neighbors. It's easy to determine the effect of
your neighbors' networks as well as your own walls, stairways, doors
and other objects on the range and performance of your network.
The inSSIDer display is neatly divided into sections. The upper left
shows the Networks Table, a list of all the networks that your adapter
can sense (but none of the kinds of devices like baby monitors, which
the computer's adapter cannot sense.) For each network detected it
shows data in columns: the SSID or name given to the network, the RSSI
or signal strength in decibels, the Channel, the Vendor of the router,
and the type of Security in use. There are more columns, but their
explanation is beyond the scope of this article. All the data may be
sorted by any category by clicking its column header, though RSSI and
Channel are the most useful for diagnosing connection problems.
Further, the data may be filtered to show only relevant channels or
vendors, for example.
The upper right section of the display has the Network Details Panel.
This area shows extra information about the network to which you're
connected and any network you select in the Networks Table. The upper
right corner of this panel shows the Link Score, a number calculated
from the signal strength and the amount of interference and cooperation
from neighboring networks. You'll also find the number of co-channel
and of overlapping neighboring networks. There's also a button to
'star' a network for special treatment in the Channels Graph.
The bottom half of the display has the Channels Graph. This is a signal
strength line graph wherein the (up-down) Y-axis represents signal
strength and the (right-left) X-axis represents channels. Networks are
labeled by name and drawn showing their real-time appearance in the
wi-fi spectrum. Once a network has been starred in the Network Details
Panel, the color of each network shown in the graph changes to
highlight your network, those networks on the same channel as your
network and those that overlap your network.
Use inSSIDer to optimize
your network's signal
Download and install inSSIDer. Launch it. When the program opens, it's
set to the Learn tab and you're presented with a little guide to using
inSSIDer. Click the Networks tab to get down to business. Next, click
your network in the Networks Table, and then click the star next to
your network's name in the Network Details Panel. If you haven't
changed your router's channel, it's probably set to channel 6, the
customary default for new routers. For this reason alone, channel 6 is
likely to be overcrowded in any given area.
Take your laptop for a walk around your place, stopping at every
possible location where someone might want to use wi-fi. Make a note of
the decibels and link score at every stop. A decibel reading below -73
could be a problem. Now change the channel on your access point (see
link below) to another “good” channel and repeat the walk around.
Finally, change the channel to the third good channel and repeat the
walk around a third time. Choose for your network the channel that
produced the highest Link Scores. If you must share a channel, choose a
channel with at least 20 decibels separation between your network's
RSSI and that of your neighbor's for best performance.
In the next article in this series, expect a detailed account of the
process of changing your router's channel.
August 8, 2013