It also doesn't protect the individual server sites in the US which are the ones really breaking the copyright laws by effectively offering on demand broadcast service for the music which is subject to royalties.
Rather poor arguement, in that you completely ignored the time scale. The big 10x improvements in ethernet, for the most part have just had a
much slower release schedule over a 2-3x longer
product life. The megabit ethernet at Xerox is nearly 40 years old, FC technology is less than 10, and the first SCSI draft is less than 20.
So if you take REAL historical scaling (IE a perfomance/date plot) into account, all the technologies share the same performance curve which is dependent upon similar tranciever technology performances.
I've been building an FC interconnect for my home office for several months, all for cheap all off Ebay. This stuff is fast, and a great bang for the buck at Ebay discount prices - $0.10-0.20/dollar.
I picked up a T-card from CS Electronics with a CU cable to test drives with... for one drive this is about the same price at the joker that spam'd us. The only real trick to making this stuff work is the FC drives are "dead" until you jumper a drive start option - the T-Card arrives without any jumpers and doesn't work if you just cable it up without the jumper.
The problem is that T-Cards cost as much, or a lot more than most of the drives I got for cheap. So I spent a week and a piece to design PCBs for two passive backplanes - a four HH drive backplane, and a six FH drive backplane. Proto PCB's are a
tad expensive, but for 10 drives is a lot cheaper than a bunch of T-Cards.
When I get done pulling fibre in the house (also cheap off ebay) it will be fun resuming some clustered/SAN filesystem research I've left idle for a few years. Fibre Channel may be dead commercially, but at the current dumpping prices is excellent high speed hobbies material. I paid a $100/ea for my 18GB FC drives off Ebay, and a lot less for the 9 & 4GB drives to build out a really fun JBOD array - and a $150-175ea for the HBA's. This isn't much more expensive than high speed SCSI.
FHSS doesn't always win - or even always work. In the "duel" when the FHSS system and DSSS system collide, both recover equally when the FHSS moves outside the DSSS's channel. Under the 802.11 protocol, both must wait for a clear channel before transmitting, and thus gracefully share the frequencies as long as there are no hidden nodes. Non-802.11 radios do not have that feature, and transmit concurrently jamming each other. In fact, in many cases the FHSS is still jammed while operating on the skirt of the DSSS channel, while the DSSS system doesn't see a problem due to the advanced signal processing techniques of DSSS.
We have several DSSS system deployed with 2000 square miles under the antenna pattern, where the ONLY reason it still works is the advanced ability of DSSS radios to recover signals under the RF noise floor. FHSS systems are completely deaf in our environment (have about 1/6th the usable range and 1/12th or less the usable bandwidth).
With several concurrent DSSS channels active in an area, FHSS systems have a hard time finding clean air space, while the DSSS systems only see minor interference from FHSS beacons and packets. When an FHSS system runs into active carrier, it is stuck nearly idle at that frequency for the remainder of the FHSS dwell period because the duration is fixed by the FHSS protocol. 1/3 of the available FHSS hopping spectrum (1MHz wide channels with 3MHz separation yielding 28 channels inside the 2400-2472MHz band) is consumed by a single DSSS system (22MHz wide channels yielding 3 non-overlapping channels) in operation.
DSSS systems mostly only have a problem when multiple FHSS systems are co-located in an area with different hopping sets for each system - but the effect isn't much different than a single FHSS system co-located with 3 or more DSSS channels active.
We run high ground (mountain top) Aironet BR500 repeaters/AccessPoints in the US which deliver about 30-31dBm of EIRP (well below the FCC max) into omni antennas and 4800 series radios with 24dBi dishes at the remote ends. We have stable links in the 16-18 mile range, and have tested out to 25miles. The hill tops have co-located high power transmitters on the sites (TV, FM, Cell Phone, paging, mobile radio repeaters, and the like) which contribute a significant amount of broadband noise to the site. As a result FHSS perform much worse than DSSS systems (which are able to recover signals below the noise floor). Our repeaters are therefor receiver noise limited, which limits our
range even though we have the remote power tuned right to the FCC max on the dishes. In theory, this stuff can work out to the horizon (65-100 miles) if the environment around the site is RF clean (very remote) - and in dicussions with the military boys it does just that in certain areas. Even so, with three hill top repeaters we have better than 30% coverage of an area 40 miles wide and 55 miles long (just over 2,000 square miles under the antenna pattern, with an effective coverage area of just less than a 1,000 square miles after subtracting out shadowed areas). We will probably double that during the next year. Our market is NON-Wired high speed services, and we suggest potential customers that can get wired access do so. Some of our customers live off the grid - no wired power/phones - most do not have access to ISDN, DSL, Cable, or T-1's. We are a member owned, member-operated cooperative, with the goal of providing ourselves the service we need (when AT&T and Qwest cann't, or won't).
We are a coop for a reason - it was clear from the beginning that you can only build out *ONE* of these wireless networks in a region. We allow equal access to our network by all regional ISP's that want to particpate for a $3K startup (includes radio/routers which are coop owned/managed) and $300/mo. In short, a turnkey service far less costly than the 2 man years and $25K it would take to rebuild the nework form scratch. Coop members pay $60/mo for service - about the same as DSL and Cable service in this area - and lot's cheaper than ISDN. We are not a free open source like entitiy... but as a member-owned, member operated cooperative, the next best thing.
Making it work more than a few miles without a 2500ft tower (aka mountain) is very difficult. Signal (wave front) diffraction is driven by pure physics... and every object the signal passes bleeds energy off the wave front to fill in behind the object. So you lose 3-6dB over every building roof and tree that you barely clear with LOS. The diffracted wave front also reflects out of phase to distort the main wave front (multi-path) - creating a noisy/choppy signal.
So flat landers with lots of buildings and trees, and no serious height, pretty much will have to live with short connections (under a mile or so),
probably much less in typical city environments. This is much less a problem at 900mhz, is difficult at 2.4GHz, and a total killer at 5.7Ghz.
While some vendors say that 2.4GHz isn't affected by weather, that is only partially true, and only for links that have 15-25dB or more of link margin. Many of our 2.4GHz links have less than 10dB of link margin, and see slight rain fade, but serious signal loss due to snow which causes serious diffraction problems coupled with broadband noise refection problems at the repeater sites (noise floor goes way up during snow storms). We manage this by dropping the modulation rate to 5.5mbps (doubles the power per bit) and decreasing the packet size (enabling fragmentation) to significantly reduce the probability of CRC errors due to noise functions. At 5.7GHz rain drops just completely eat the signal, and rain fade is really rain-block.
Network performance with Hidden node operation, while managed by 802.11b, degrades rapidly underload. Aironet made a huge mistake when they failed to implement the Point Coordination Function called for in the 802.11 spec (PCF). In theory PCF can be used to stabilize the load curve, minimize load induced failures/overruns, which are a fact of life with hidden node architectures when using 802.11 devices in a wide area network.
There is a lot of RF magic in making 2.4GHz 802.11 wide area networks work - the stuff is worse than plug-and-pray. It pretty much takes a $2-20K spectrum analyzer investment to debug problems. Even with that expect side by side experiments to have radically different results.
Watchout for mixing FHSS and DSSS systems in the same area... they do not mix well in weak signal applications. In close applications, the 802.11 spec requires them to check for energy in the channel and hold-off transmissions to minimize collisions. In wide area applications with all hidden nodes, they do not sense each other, and collisions rapidly degrade to inoperation.
Or operation isn't perfect... we do see brief periods of in-band interference, and high-power broadband interference which causes several second to several minute drop-outs in our service. Sometimes several per week, sometimes several per hour. But compared to unstable 19.2kbps dialup on rural phone lines... it is completely heaven to get megabit web surfing with dedicated connections.
Damn good question. Bandwidth to the internet is
anything but free. Nearly all ISP's have restrictions against resale and/or aggregation (running an entire subdivision or apartment complex on a single account). Even behind a NAT box, none of the cable subscribers would be safe. It wouldn't take long for the word to get out, and the techies from the cable company would join the wireless network and start tracerouting out to find the connection points (and terminating them).
When we started our community wireless network the difficult question was the cost of a T-1 to an affordable upstream provider that would allow resale. Ultimately one of the local ISP's agreed to sell us bandwidth reasonable in exchange for providing transport to their customers. It costs us about $12-17/user in bandwidth charges for each user we add to our wireless network. Our connection is metered, so our members have to be carefull not to get carried away with MP3's and mirroring the entire internet.
In many communities, local schools and governments purchase bandwidth from regional ISP's... so it's not likely that tax role agencies are going to provide free ISP service to the community (since their "costs" would rise quickly). A more likely source would be working with NetZero type companies in exchange for advertising revenues.
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Adding the missing features that most companies need, and missing from OpenSource DB's would cost much more in just labor for the first year.
It also doesn't protect the individual server sites in the US which are the ones really breaking the copyright laws by effectively offering on demand broadcast service for the music which is subject to royalties.
Rather poor arguement, in that you completely ignored the time scale. The big 10x improvements in ethernet, for the most part have just had a much slower release schedule over a 2-3x longer product life. The megabit ethernet at Xerox is nearly 40 years old, FC technology is less than 10, and the first SCSI draft is less than 20.
So if you take REAL historical scaling (IE a perfomance/date plot) into account, all the technologies share the same performance curve which is dependent upon similar tranciever technology performances.
I've been building an FC interconnect for my home office for several months, all for cheap all off Ebay. This stuff is fast, and a great bang for the buck at Ebay discount prices - $0.10-0.20/dollar. I picked up a T-card from CS Electronics with a CU cable to test drives with ... for one drive this is about the same price at the joker that spam'd us. The only real trick to making this stuff work is the FC drives are "dead" until you jumper a drive start option - the T-Card arrives without any jumpers and doesn't work if you just cable it up without the jumper.
The problem is that T-Cards cost as much, or a lot more than most of the drives I got for cheap. So I spent a week and a piece to design PCBs for two passive backplanes - a four HH drive backplane, and a six FH drive backplane. Proto PCB's are a tad expensive, but for 10 drives is a lot cheaper than a bunch of T-Cards.
When I get done pulling fibre in the house (also cheap off ebay) it will be fun resuming some clustered/SAN filesystem research I've left idle for a few years. Fibre Channel may be dead commercially, but at the current dumpping prices is excellent high speed hobbies material. I paid a $100/ea for my 18GB FC drives off Ebay, and a lot less for the 9 & 4GB drives to build out a really fun JBOD array - and a $150-175ea for the HBA's. This isn't much more expensive than high speed SCSI.
FHSS doesn't always win - or even always work. In the "duel" when the FHSS system and DSSS system collide, both recover equally when the FHSS moves outside the DSSS's channel. Under the 802.11 protocol, both must wait for a clear channel before transmitting, and thus gracefully share the frequencies as long as there are no hidden nodes. Non-802.11 radios do not have that feature, and transmit concurrently jamming each other. In fact, in many cases the FHSS is still jammed while operating on the skirt of the DSSS channel, while the DSSS system doesn't see a problem due to the advanced signal processing techniques of DSSS.
We have several DSSS system deployed with 2000 square miles under the antenna pattern, where the ONLY reason it still works is the advanced ability of DSSS radios to recover signals under the RF noise floor. FHSS systems are completely deaf in our environment (have about 1/6th the usable range and 1/12th or less the usable bandwidth).
With several concurrent DSSS channels active in an area, FHSS systems have a hard time finding clean air space, while the DSSS systems only see minor interference from FHSS beacons and packets. When an FHSS system runs into active carrier, it is stuck nearly idle at that frequency for the remainder of the FHSS dwell period because the duration is fixed by the FHSS protocol. 1/3 of the available FHSS hopping spectrum (1MHz wide channels with 3MHz separation yielding 28 channels inside the 2400-2472MHz band) is consumed by a single DSSS system (22MHz wide channels yielding 3 non-overlapping channels) in operation.
DSSS systems mostly only have a problem when multiple FHSS systems are co-located in an area with different hopping sets for each system - but the effect isn't much different than a single FHSS system co-located with 3 or more DSSS channels active.
We run high ground (mountain top) Aironet BR500 repeaters/AccessPoints in the US which deliver about 30-31dBm of EIRP (well below the FCC max) into omni antennas and 4800 series radios with 24dBi dishes at the remote ends. We have stable links in the 16-18 mile range, and have tested out to 25miles. The hill tops have co-located high power transmitters on the sites (TV, FM, Cell Phone, paging, mobile radio repeaters, and the like) which contribute a significant amount of broadband noise to the site. As a result FHSS perform much worse than DSSS systems (which are able to recover signals below the noise floor). Our repeaters are therefor receiver noise limited, which limits our range even though we have the remote power tuned right to the FCC max on the dishes. In theory, this stuff can work out to the horizon (65-100 miles) if the environment around the site is RF clean (very remote) - and in dicussions with the military boys it does just that in certain areas. Even so, with three hill top repeaters we have better than 30% coverage of an area 40 miles wide and 55 miles long (just over 2,000 square miles under the antenna pattern, with an effective coverage area of just less than a 1,000 square miles after subtracting out shadowed areas). We will probably double that during the next year. Our market is NON-Wired high speed services, and we suggest potential customers that can get wired access do so. Some of our customers live off the grid - no wired power/phones - most do not have access to ISDN, DSL, Cable, or T-1's. We are a member owned, member-operated cooperative, with the goal of providing ourselves the service we need (when AT&T and Qwest cann't, or won't).
... but as a member-owned, member operated cooperative, the next best thing.
... and every object the signal passes bleeds energy off the wave front to fill in behind the object. So you lose 3-6dB over every building roof and tree that you barely clear with LOS. The diffracted wave front also reflects out of phase to distort the main wave front (multi-path) - creating a noisy/choppy signal.
... they do not mix well in weak signal applications. In close applications, the 802.11 spec requires them to check for energy in the channel and hold-off transmissions to minimize collisions. In wide area applications with all hidden nodes, they do not sense each other, and collisions rapidly degrade to inoperation.
... we do see brief periods of in-band interference, and high-power broadband interference which causes several second to several minute drop-outs in our service. Sometimes several per week, sometimes several per hour. But compared to unstable 19.2kbps dialup on rural phone lines ... it is completely heaven to get megabit web surfing with dedicated connections.
We are a coop for a reason - it was clear from the beginning that you can only build out *ONE* of these wireless networks in a region. We allow equal access to our network by all regional ISP's that want to particpate for a $3K startup (includes radio/routers which are coop owned/managed) and $300/mo. In short, a turnkey service far less costly than the 2 man years and $25K it would take to rebuild the nework form scratch. Coop members pay $60/mo for service - about the same as DSL and Cable service in this area - and lot's cheaper than ISDN. We are not a free open source like entitiy
Making it work more than a few miles without a 2500ft tower (aka mountain) is very difficult. Signal (wave front) diffraction is driven by pure physics
So flat landers with lots of buildings and trees, and no serious height, pretty much will have to live with short connections (under a mile or so), probably much less in typical city environments. This is much less a problem at 900mhz, is difficult at 2.4GHz, and a total killer at 5.7Ghz.
While some vendors say that 2.4GHz isn't affected by weather, that is only partially true, and only for links that have 15-25dB or more of link margin. Many of our 2.4GHz links have less than 10dB of link margin, and see slight rain fade, but serious signal loss due to snow which causes serious diffraction problems coupled with broadband noise refection problems at the repeater sites (noise floor goes way up during snow storms). We manage this by dropping the modulation rate to 5.5mbps (doubles the power per bit) and decreasing the packet size (enabling fragmentation) to significantly reduce the probability of CRC errors due to noise functions. At 5.7GHz rain drops just completely eat the signal, and rain fade is really rain-block.
Network performance with Hidden node operation, while managed by 802.11b, degrades rapidly underload. Aironet made a huge mistake when they failed to implement the Point Coordination Function called for in the 802.11 spec (PCF). In theory PCF can be used to stabilize the load curve, minimize load induced failures/overruns, which are a fact of life with hidden node architectures when using 802.11 devices in a wide area network.
There is a lot of RF magic in making 2.4GHz 802.11 wide area networks work - the stuff is worse than plug-and-pray. It pretty much takes a $2-20K spectrum analyzer investment to debug problems. Even with that expect side by side experiments to have radically different results.
Watchout for mixing FHSS and DSSS systems in the same area
Or operation isn't perfect
Damn good question. Bandwidth to the internet is anything but free. Nearly all ISP's have restrictions against resale and/or aggregation (running an entire subdivision or apartment complex on a single account). Even behind a NAT box, none of the cable subscribers would be safe. It wouldn't take long for the word to get out, and the techies from the cable company would join the wireless network and start tracerouting out to find the connection points (and terminating them). When we started our community wireless network the difficult question was the cost of a T-1 to an affordable upstream provider that would allow resale. Ultimately one of the local ISP's agreed to sell us bandwidth reasonable in exchange for providing transport to their customers. It costs us about $12-17/user in bandwidth charges for each user we add to our wireless network. Our connection is metered, so our members have to be carefull not to get carried away with MP3's and mirroring the entire internet. In many communities, local schools and governments purchase bandwidth from regional ISP's ... so it's not likely that tax role agencies are going to provide free ISP service to the community (since their "costs" would rise quickly). A more likely source would be working with NetZero type companies in exchange for advertising revenues.