Slashdot Mirror
FCC Chairman Warns of Wireless Spectrum Gap
locallyunscene writes "'We are fast entering a world where mass-market mobile devices consume thousands of megabytes each month,' FCC Chairman Julius Genachowski warned at CTIA Wireless yesterday. 'So we must ask: what happens when every mobile user has an iPhone, a Palm Pre, a BlackBerry Tour, or whatever the next device is? What happens when we quadruple the number of subscribers with mobile broadband on their laptops or netbooks?'"
http://en.wikipedia.org/wiki/Ultra_High_Frequency#United_States_2
Doesn't look like the US military uses much of the wireless spectrum... am I missing something?
>>>Once the air is saturated on the allocated frequencies, we are done
Not quite "done". We can say goodbye to over-the-air FM and TV. We already lost channels 52 to 83 that were turned-over to cellphones, and I suspect it's only a matter of time until channels 2 to 51 (including the FM band) disappear. That would not meet the FCC's "30 fold" estimate, but it would increase the available wireless spectrum by about 9 times present levels.
Lower frequency shortwave and AM radio will probably survive, simply because it's not practical to carry-around 100 foot long transmitting antennas with your phone.
"I disapprove of what you say, but I will defend to the death your right to say it." - historian Evelyn Beatrice Hall
802.11 based systems aren't good at many things that existing cellular systems are. It doesn't have soft handoffs and doesn't work well when the same network has adjacent cells using the same channel. For 2.4 GHz 802.11, there are only 3 non-overlapping channels.
802.11 can't support devices at the same distances / similar power as modern cellular networks.
No DSL is *not* over telephone lines. POTS (plain old telephone service) is defined as having a 0 to 8000 hertz bandwidth, hence the 56k dialup limit. The engineers have squeezed as much data as they can into that limited range.
DSL disconnects the POTS line, and replaces it with a central box (DSLAM) that converts the incoming twisted-pair and passes it along to higher-quality fiber or coax.
BTW thanks for modding me "troll" kevinmenzel.
-1 I disagree is not why moderation exists.
"I disapprove of what you say, but I will defend to the death your right to say it." - historian Evelyn Beatrice Hall
Analog phone lines are indeed no faster than 56 kbits/second
For the sake of clarity analog phone lines are inherently limited to 2400 bits/second (bps). Better compression algorithms got us up to 56 kbps.
For the sake of clarity, you don't know what the fuck you're talking about. 56-kbits/second is the max because that's what the analog-digital converters within the telco are set for. A DS0 phone circuit is by definition a 56k or 64k digital channel (depends on inband or out-of-band signalling). The early 2400 and 4800 limits were due to poor quality lines and equipment that just wasn't setup to go faster. This was back when most users were just doing text and fax machines were the bandwidth intensive applications.
The magic of 56k comes from the users modem being able to synchronize its timing and discrete output levels (the "constellation") to match the analog-digital converter attached to the users phone line. The server end of the circuit must be digitally connected for this to work.