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802.11b at 22mbps
Radi-0-head writes "According to this article at PCWorld.com, "U.S. Robotics (USR) has boosted the speed of its latest range of wireless LAN products for small businesses to 22 megabits per second, while retaining compatibility with existing 2.4-GHz systems built to the IEEE 802.11b standard..." Sounds to me like a great alternative to 802.11a."
A nearly free 100% speed boost is nice, but I would wait for 802.11g instead, giving 54Mbps in the 2.4GHz band and also being backward compatible with 802.11b.
I'm not an expert, but it seems to me 802.11a is doomed. Is there any reason to prefer it over the upcoming 54Mbps 2.4GHz stuff?
Oh, God no, not proprietary USR hardware that gives superior connection speeds! Not a return to the bad old days!
Shutting down free speech with violence isn't fighting fascism. It IS fascism!
This isn't terribly new. Companies have been doing 22Mbps 802.11 for awhile now: Link from 6/2001
Wow!! 22 millibits per second. That means it only takes 45 seconds to transfer a whole bit!
I can't wait until 22Mbps devices come out.
One of these days/I'm going to cut you into little pieces.
11 Mbps to 22 Mbps SOUNDS like a 100% increase, but what is the real speed/range gain? Given an 11 Mbps system with 3 nodes each at 10m from the access point, what is the actual thruput? Is switching to the USR system going to actually DOUBLE that?
Network speeds rank right up there with CRT sizes, CD-ROM spin speeds and tape storage capacity as some of the biggest bullshit numbers in computing.
Learning HOW to think is more important than learning WHAT to think.
Reality has a liberal bias
These chips double 802.11b speeds by functioning full duplex. The drawback however, is that this requires category 5 air.
Not all offices and homes fulfill this requirement. Location plays an important role: in the city you'll most likely not be able to communicate full duplex. In suburbs you'll have a fair chance if you're not too close to the city. In rural area's you'll most probably always have full duplex.
You can communicate at 22 Mbps over short distances using category 4 air, but when the peers are more than a few meters apart, category 5 air becomes a must.
Just something you might want to know before you buy these things..
USR does not have a esitmated market release for their new cards (this from a USR sales person).
t io n2x/index.cfm
Some other companies have also started producing the new standard, notably BuffaloTech.
http://www.buffalotech.com/news/prelease/airsta
Any insider information as to when these cards can bought at a local Bestbuy ?
First, the 2.4 GHz has a ton of other devices sharing the same spectrum, from Bluetooth to wireless headphones, to your microwave. 802.11a runs in the 5GHz band instead.
.11b APs will.
Second, according to the last proposals I'd heard of, 802.11g is going to achieve higher bandwidth by taking up more of the spectrum. In other words, it is going to use more channels to simultaneously broadcast data, rather than just being able to shove more data down the same channel. This means your own access points will begin to interfere with each other much sooner than your 802.11a or
In general, it is going to depend on your situation as to which you wish to choose. 802.11g will be great for backwards compatibility, but the news coming out of IEEE seems to indicate that 54Mbps is more like something to shoot for than something they expect to achieve. 802.11a won't have compatibility, and it will also have a shorter range, but it will have higher speeds with less interference.
Seriously, I really want secure security!
Run ipsec or some other form of end-to-end encryption or vpn. Put the wireless network on a separate interface (a la DMZ) on one of your routers. That's it - it's probably safer than your cat5 now.
if you use a good enough junk-filter, slashdot.org will display a single, *blank*, page
802.11b
pros:
11Mbps at low cost. Many vendors.
cons:
802.11b operates in 2.4GHz, which collides with among other things, bluetooth, wireless phones, and microwave ovens.
802.11a
pros:
Higher speed at 54 Mbps
Operates in 5 GHZ which is less used
cons:
New radios and antennas required if used to replace existing 802.11b network
802.11g
pros:
Higher speed at 54 Mbps and includes backward compatibility to existing 802.11b equipment
Antennas can be resued if used to replace existing 802.11b network
cons:
Operates in 2.4GHz, which collides with among other things, bluetooth, wireless phones, and microwave ovens.
New radios required because of new chipsets
Sorry, I can't tell you whether a or g is going to replace b, and at what speed existing b users will change to new technology.
11g is really 11a-style OFDM at 2.4 Ghz rather than the 5 Ghz band. There would be two (at least) 11g modes: a compatibility mode whereby OFDM packets and legacy 11b CCK packets coexist, and one which is "pure" OFDM at 2.4 Ghz.
... and these differences are quite small if you have a good 11a radio with a good antenna.
The compatibility mode adds a huge overhead to each transmitted packet. An 11g transmitter in this mode must first complete a legacy 11b RTS/CTS operation on the air which, if successful, is followed by the actual packet. Even if the actual packet were transmitted at nearly infinite bandwidth, the effective bandwidth you'd see on a connection would be quite low - think 10 Mb/s on average. That's not exactly chopped liver and its way better than legacy 11b, but it's definitely not 54 Mb/s.
There are suprisingly large differences between 11a products, even those using the exact same vlsi chips. There are two primary reasons: differences in choice of output power amplifier (or lack thereof) and differences in choice of antenna.
You can deduce some of what's going on by looking
at power and sensitivity ratings in manufacturers product specs. By the way, this also a great way to distinguish between 11b products as well.
Second generation 11a products have much better receiver sensitivity and output power than the first generation versions. And they do transmit through walls... although not concrete or metal or mirrors or some ceramics.
The main reason why 11b can reach farther than 11a in some situations is that 11b can ratchet down to 1 Mb/s whereas 11a is defined for rates from 54 down to 6 Mb/s (11g is identical to 11a in this regard). The difference in SNR and sensitivity needed at a receiver to pick out the 11a or 11g signal accounts for nearly all of the differences in range
Thus, 11g will have the same power, SNR, and receiver sensitivity challenges as 11a in the 5 Ghz band, but will also have a small boost in signal propagation efficiency in the lower band.
Don't get bamboozled by the hype about compatibility with 11b. Compatibility for sharing the channel does not imply that the radio properties of 11g are the same as 11b.
Most vendors are busy bringing out 11a+b base stations and NIC cards. 11g in compatibility mode looks like a nightmare, whereas 11g in "pure" mode looks like 3 more channels of high performance OFDM if you have an 11a radio that can tune to both the 5Ghz and 2.4 Ghz bands. Aside from the higher-power outdoor channels at 5.8, this provides 11 channels for OFDM (8 at 5 Ghz plus 3).
And this means that a group of base stations in an AP-dense environment will certainly be able to find a clear channel.
I didn't say much about the PBCC-based 22 Mb/s products. PBCC is actually a clever design but is likely going to be overshadowed by OFDM at 5 Ghz (11a) and OFDM at 2.4 Ghz (11g variants).
My USR Courier MODEM, now being about 7 years old (my model) was first a V.34 28.8k MODEM, then upgraded to V.34bis 33.6k with a simple firmware download, then X2 56k, then V.90 56k and now it seems, after 7 years, it will be upgradable to V.92 soon.
With an Intel 80186 20MHz (25MHz for US model), TI DSP, flash memory, etc, it is one heavily over engineered beast of a MODEM.
Does'nt surprise me that the company to get extra performance out of a technology, is USR.
War crimes, torture, lies, illegal spying... Would someone give Bush a blowjob, already, so he can be impeached?