This is a pretty stupid approach from the communications theory point of view. 802.11b frames contain a pretty long preamble in front of the packet header and data payload. This preamble (basically 11-bit barker sequences convolved with a prn-sequence) have excellent autocorrelation characteristics since they must be used for time and frequency syncronization at the RX station. By cross correlating the received signal with the (known) barker sequence at all three base stations precision would be increased drastically as it would be possible to measure the actual time lag (->way) the signal took to the receiver.
Maybe they should concentrate on approving the 11g
standard first.
Just to comment on the "users of 11g" stuff: The implementations you are currently
seeing in the shops are based upon more or less
early *drafts* of the standard. The fit will really
start hitting the shan when people start combining devices from different manufacturers: Incompatibilities range from different modulation
schemes (TI) over incompatible MAC protocol elements
(dataset identifiers in AP capabilities) to legacy
support (some old legacy devices refuse to associate with APs supporting the new modulation
modes due to excessive supported-rates-list lengths).
The origin of the slow effective transfer speed
by the way is the MAC layer timing. Each information frame is transfered independently and
ACK'ed by the receiving station on MAC layer -- the time delays in these frame exchanges take up enough time to reduce the effective transfer rate to about half for the 54Mbps mode. Besides QoS 11e will introduce burst frame acknowledge which
should improve the situation considerably and therefore the new modulation schemes may actually
make sense.
The metal measurement tape omnidirectional antenna system was already used on the AMSAT AO-40 hamradio satellite slashdot already posted news stories about a couple of times. The interesting part is that both antennaes which used that system failed mysteriously (or alternatively the transmitters did, this is not for sure yet).
Tantalum capacitors are to popular because of their high capacity and low equivalent series resistence (ESR). There are, however, some alternatives by now. A good candidate is the multi layer ceramic capacitor which reaches almost the same specific capacity values and same low series resistence characteristics. They are, however, still much more expensive then the tantalum capacitor types. They are more expensive though.
The funny thing is that this implies that someone could use this vulnerability to intrude the server system and backdoor the update packages people are downloading to "fix" their systems...
Micosoft should really know better than that.
The best thing about OS/2 always was the graphical user interface. Way ahead of their time with their object model and OpenDoc OLE concepts. Everything else (even KDE and M$ Windows) is still far behind. Would have been great to have it run on freeBSD or Linux. Great stable operating system with acceptable driver support and a decent GUI would *really* have been successful.
In Germany there is some competition called "Jugend Forscht", which allows young people (school pupils etc.) to present their inventions. This year the 1st price in the "technics" section went to somebody who managed to trick the (academical) jury into believing he was able to expand a GSM network's bandwith to 550kbps, rendering UMTS and the whole 3rd-generation mobile-service useless, just with fiddling around a little bit with the handies.
That's not all, two big German news magazines and (at least) one federal TV channel came along and
made reports out of it. (see http://www.heise.de/presseinfo/ct/00/08_11_b.shtml )
The first time I saw this on TV I did not know whether I should burst in laugh about their stupidity or start to cry about what happened to Germany.
However, there is one thing for sure:
If I was in the recruitment section of a big company I would hire these guys at once. I suspect the value of such people for marketing purposes is vitally unlimited.
Slashdot Mirror
This is a pretty stupid approach from the communications theory point of view. 802.11b frames contain a pretty long preamble in front of the packet header and data payload. This preamble (basically 11-bit barker sequences convolved with a prn-sequence) have excellent autocorrelation characteristics since they must be used for time and frequency syncronization at the RX station.
By cross correlating the received signal with the (known) barker sequence at all three base stations precision would be increased drastically as it would be possible to measure the actual time lag (->way) the signal took to the receiver.
Maybe they should concentrate on approving the 11g standard first.
Just to comment on the "users of 11g" stuff: The implementations you are currently seeing in the shops are based upon more or less early *drafts* of the standard. The fit will really start hitting the shan when people start combining devices from different manufacturers: Incompatibilities range from different modulation schemes (TI) over incompatible MAC protocol elements (dataset identifiers in AP capabilities) to legacy support (some old legacy devices refuse to associate with APs supporting the new modulation modes due to excessive supported-rates-list lengths).
The origin of the slow effective transfer speed by the way is the MAC layer timing. Each information frame is transfered independently and ACK'ed by the receiving station on MAC layer -- the time delays in these frame exchanges take up enough time to reduce the effective transfer rate to about half for the 54Mbps mode. Besides QoS 11e will introduce burst frame acknowledge which should improve the situation considerably and therefore the new modulation schemes may actually make sense.
The metal measurement tape omnidirectional antenna system was already used on the AMSAT AO-40 hamradio satellite slashdot already posted news stories about a couple of times. The interesting part is that both antennaes which used that system failed mysteriously (or alternatively the transmitters did, this is not for sure yet).
Tantalum capacitors are to popular because of their high capacity and low equivalent series resistence (ESR). There are, however, some alternatives by now. A good candidate is the multi layer ceramic capacitor which reaches almost the same specific capacity values and same low series resistence characteristics. They are, however, still much more expensive then the tantalum capacitor types. They are more expensive though.
Here is a link to a FAQ about AMD's HyperTransport technology.
It works at 6.4GB/sec and looks to me like a direct competitor.
The funny thing is that this implies that someone could use this vulnerability to intrude the server system and backdoor the update packages people are downloading to "fix" their systems...
Micosoft should really know better than that.
The best thing about OS/2 always was the graphical user interface. Way ahead of their time with their object model and OpenDoc OLE concepts. Everything else (even KDE and M$ Windows) is still far behind. Would have been great to have it run on freeBSD or Linux. Great stable operating system with acceptable driver support and a decent GUI would *really* have been successful.
The first time I saw this on TV I did not know whether I should burst in laugh about their stupidity or start to cry about what happened to Germany. However, there is one thing for sure: If I was in the recruitment section of a big company I would hire these guys at once. I suspect the value of such people for marketing purposes is vitally unlimited.