PC Magazine - 2009 04.pdf - Libertad Zero - Blog

802.11-based products for interoperability—has
two task groups working on these
instant peer-to-peer (P2P) communications.
The first group is looking to improve
the existing ad hoc protocol, according
to Kelly Davis-Felner, marketing director
for the Alliance. The second is developing
a “soft AP,” software that makes a client
device like a laptop appear and work
as an infrastructure AP. That way, multiple
devices can connect to it directly.
The soft AP approach may be getting an
assist, since Intel is backing it. At the Consumer
Electronics Show (CES) in January,
the company—whose Wi-Fi chips power a
huge number of laptops—showed off a soft
AP under the name My Wi-Fi. The software
ran on laptops with Intel Centrino 2
chipsets, making each laptop the center of a
personal area network connecting as many
as eight Wi-Fi devices at once. The laptop
maintained a separate connection to a real
AP, however, so it could, for example, share
an Internet connection with all attached
devices. Reports say My Wi-Fi also can be
used to connect peripherals, even audio
receivers for streaming from the laptop.
Key for both Alliance groups is making
sure these P2P connections are secured
using Wi-Fi Protected Setup, the simple,
one-button security configuration created
by the Wi-Fi Alliance
to improve on Wi-
Fi Protected Access
(WPA2), which is in
turn based on the IEEE
802.11i specification.
The layers upon layers
of support in this arena
are mind-boggling.
Why two groups? The Alliance doesn’t
know which technology the industry will
prefer. It doesn’t even have a name for this
enhanced P2P connection yet. Another
consideration: Who would use it? Davis-
Felner believes consumers would like it
for quicker content transfers, file synchronization,
and more, and that big corporate
enterprises could expect it to help with
direct connections to peripherals like printers
and projectors. “Enterprise IT people
should feel comfortable with it,” she says.
IEEE: More Speed (Eventually)
The IEEE (Institute of Electrical and
Electronics Engineers) may be the most
democratic organizational body ever conceived—sometimes
to a fault. Every member
gets a say, which is partly why, almost
38 PC MAGAZINE DIGITAL EDITION APRIL 2009
five years after debates began on the initial
proposal, the “High Throughput” standard
for wireless networks—better known
as 802.11n—is still not ratified. In fact, it’s
unlikely to be ratified by the IEEE’s 802.11
Working Group for another year.
802.11n is done enough, however, and
that’s why there are plenty of 11n-based
Wi-Fi products on store shelves, satisfying
those who need increased speed and
range. So tabling that discussion, what
might the IEEE have up its sleeves for after
11n? Plenty, it turns out.
Let’s be clear on the terms. Within the
IEEE there are working groups for all types
of technologies. Wireless LAN (WLAN)
just happens to go by the name 802.11,
whereas Ethernet goes by 802.3. Within
each working group are task groups, usually
identified by a letter, such as the “n” of
802.11n; these groups are actively working
on technology specifications to amend
the original. Before a task group can exist,
it is a study group, wherein members toss
around the idea and see if anyone even
cares enough to pursue it. Then there’s
balloting, editing, and changes, ad infinitum—sometimes
for years.
The reason 11n has been so important
for so long is because it’s about increases:
more throughput and better range on wire-
WI-FI ThroughpuT: WhaT’S avaIlablE NoW
Specification throughput frequency compatibility
802.11b 11 mbps 2.4 ghz Works with 802.11g
802.11g 54 mbps 2.4 ghz Works with 802.11b
802.11a 54 mbps 5 ghz Works with 802.11n
802.11n ranges from 150 to 600 mbps either 2.4 ghz or 5 ghz Works with 802.11a, b, or g
less networks—boosts that everyone wants.
Thus it’s no surprise that not one but two
task groups were spawned from the “Very
High Throughput” study group—there’s
TGac and TGad. The TG is for Task Group;
these may eventually translate to 802.11ac
or 802.11ad, if they go anywhere.
According to Bruce Kraemer, chair of
the 802.11 Working Group, TGac “might
double what we have now” for WLAN
speed by increasing the total data throughput
available to a cluster of users in a
relatively dense environment. It won’t do
much for an individual, but the difference
for a large number of users could be significant,
possibly in a business or even in a
cluster of users at an airport hot spot.
TGad is a whole different beast, as it
will venture into radio-band frequencies
new to Wi-Fi: the 60-GHz spectrum. Like
the 2.4-GHz and 5-GHz frequencies used
today, 60-GHz is unlicensed by the Federal
Communications Commission, so anyone
can use it. (Wikipedia says 60-GHz is useful
for short-range data links of 1.7km (1.06
miles) with throughput of up to 2.5 gigabits
per second.) Kraemer says while “ac might
go to a 2-to-1 increase, ‘ad’ could bring a
data-rate increase of 10 to 1.” However,
using new spectrum means an entirely new
radio technology, so there will be no backward
compatibility with existing Wi-Fi.
When can we expect to see 11ac or 11ad?
Not for a while; in a year or more they
might be out of the initial discussion stage.
Of course, there’s a lot more cooking
than just those two potential amendments.
There’s also 802.11s, a mesh-networking
specification that’s been on the drawing
board since September 2003. (It probably
won’t be final until September 2010.) Laptops
and other devices with 11s support will
function as mesh points (or MPs) and form
links with each other, allowing packets of
data to skip from device to device across
the network as needed.
Mesh has been around for a while in
many proprietary forms, and is important
not only because it can extend a network’s
range but also because it has self-configuring
abilities: Mesh
devices can move about
without impacting
overall performance.
In such a network, data
will hop around from
mesh point to mesh
point along the shortest
path to where it needs
to go. Actual 11s is already in use in at least
one product: the One Laptop per Child
project’s XO laptop uses it to communicate
with XS school servers, in some tests over
distances as great as 2km (1.2 miles) with
802.11s data hops from device to device.
802.11u will provide a Wi-Fi device
with methods of connecting securely to a
network, based on the external network’s
type. For example, if you have access to the
cellular connection that provides Internet
access to the Wi-Fi router on a bus, 11u will
keep that connection secure. It will also
allow a Wi-Fi device to discover more
information about that external network,
such as whether it’s free of charge or not.
11u could be published by March 2010.
Finally, 802.11z “Direct Link Setup”
is the 802.11 Working Group’s take on