802.11b at 22mbps 137
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."
more on this (Score:2, Informative)
nothing new (Score:4, Informative)
Re:802.11g (Score:2, Informative)
Thats nothing. Apple is working on 112Mbps (Score:3, Informative)
Because you can always... (Score:1, Informative)
Market Release (Score:3, Informative)
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 ?
A couple reasons to choose 802.11a over 802.11g (Score:5, Informative)
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.
Re:I'll Still Trade Security for Bandwidth (Score:5, Informative)
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.
Re:802.11a is 54Mbs (Score:2, Informative)
And it has been proven by Wifi companies like Atheros that OFDM is more robust that DSSS techniques.
It doesn't matter if you can put 1Gbps into the air channel if your packet error rate suffers so much that you have an effective rate of 10bps.
This is where 802.11a shines with its forward error schemes, interleaving, OFDM instead of DSSS Barker sequences like 802.11b.
OFDM will also allow the use of more channels so 802.11a SPEC could be updated later to more than the 48 channels for data comunication.
They could update it to have 96 true channels and make it work at ~110Mbs or higher with schemes like 256-QAM instead of 64-QAM. That would be a byte encoded symbol per channel! It would then be easy to have 144Mbs with little work on the spec!
Short summary of 802.11a, 11b, and 11g (Score:3, Informative)
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.
11a,b,g factoids (Score:4, Informative)
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).
Re:11a,b,g factoids (Score:1, Informative)
This is the so called "mandatory" mode of the proposed (and not yet approved 11g). What is being marketed now are the optional 22 Mbps modulations also in the draft yet unlikely to be supported by the majority of the implementations.