Wireless is bad for you, confirmed

[Dragon]

http://www.telegraph.co.uk/news/ukn...uld-be-banned-from-schools,-say-teachers.html

 

[agatward]

I'd like to see exactly how they compare WiFi to mobile phone masts, given the following:

• WiFi uses 2.4GHz or 5.0-5.8GHz ISM bands, with a maximum transmit power of 200mW for indoor use. Mobile phone masts in the UK use either 800MHz, 900MHz, 1700MHz or 1800MHz bands, which have to be licensed and they have a much larger transmit power, often in tens or hundreds of Watts, depending on the cell size.
• The higher the frequency, the greater the loss in free air.
• The antennae of mobile phones are frequently closer to soft tissues and organs than the antennae on WiFi devices.
• Modern WiFi equipment intelligently measures the RSSI value for a device and transmits data destined for that device with an appropriate power level.
• WiFi works on the principle of lots of small cells, much smaller than GSM cells. The higher the concentration of the APs, the lower the required transmit power from each AP and from the clients.
• Aircraft landing RADAR systems use the same band as the 5GHz WiFi (802.11a) at much higher transmit powers, yet there is no comment about schools being in the line of sight of these transmitters.

Many other pieces of equipment also use the 2.4GHz ISM band - wireless CCTV cameras, DECT phones, some walkie talkies, short-range video senders, and a whole plethora of other 'license-free wireless' devices. Why are people just concentrating on WiFi and not also investigating these other uses of the frequency band; many of which often transmit for longer bursts than WiFi, or don't use DSSS modulation techniques so have higher power peaks at particular frequencies rather than distributing the data and transmit power over a wider frequency spectrum.

If you ask me, it's just the teachers being scared the little darlings will find out what they're being taught is a load of cobblers!

 

[Dragon]

I'd like to see exactly how they compare WiFi to mobile phone masts, given the following:

• WiFi uses 2.4GHz or 5.0-5.8GHz ISM bands, with a maximum transmit power of 200mW for indoor use. Mobile phone masts in the UK use either 800MHz, 900MHz, 1700MHz or 1800MHz bands, which have to be licensed and they have a much larger transmit power, often in tens or hundreds of Watts, depending on the cell size.
• The higher the frequency, the greater the loss in free air.
• The antennae of mobile phones are frequently closer to soft tissues and organs than the antennae on WiFi devices.
• Modern WiFi equipment intelligently measures the RSSI value for a device and transmits data destined for that device with an appropriate power level.
• WiFi works on the principle of lots of small cells, much smaller than GSM cells. The higher the concentration of the APs, the lower the required transmit power from each AP and from the clients.
• Aircraft landing RADAR systems use the same band as the 5GHz WiFi (802.11a) at much higher transmit powers, yet there is no comment about schools being in the line of sight of these transmitters.

Many other pieces of equipment also use the 2.4GHz ISM band - wireless CCTV cameras, DECT phones, some walkie talkies, short-range video senders, and a whole plethora of other 'license-free wireless' devices. Why are people just concentrating on WiFi and not also investigating these other uses of the frequency band; many of which often transmit for longer bursts than WiFi, or don't use DSSS modulation techniques so have higher power peaks at particular frequencies rather than distributing the data and transmit power over a wider frequency spectrum.

If you ask me, it's just the teachers being scared the little darlings will find out what they're being taught is a load of cobblers!

I was in a customer house the other night and he complained about poor and slow wireless signal. I pointed the big mirror in the bedroom is the contribution of the poor wireless signal just 20 feet apart. He argued with me the router is just the transmitter and the wireless adapter is just a receiver. How true is this? If the wireless adapter is not also a transmitter how do the router receive signal what website to go to?

 

[columb]

I'd like to see exactly how they compare WiFi to mobile phone masts, given the following:

• WiFi uses 2.4GHz or 5.0-5.8GHz ISM bands, with a maximum transmit power of 200mW for indoor use. Mobile phone masts in the UK use either 800MHz, 900MHz, 1700MHz or 1800MHz bands, which have to be licensed and they have a much larger transmit power, often in tens or hundreds of Watts, depending on the cell size.
• The higher the frequency, the greater the loss in free air.
• The antennae of mobile phones are frequently closer to soft tissues and organs than the antennae on WiFi devices.
• Modern WiFi equipment intelligently measures the RSSI value for a device and transmits data destined for that device with an appropriate power level.
• WiFi works on the principle of lots of small cells, much smaller than GSM cells. The higher the concentration of the APs, the lower the required transmit power from each AP and from the clients.
• Aircraft landing RADAR systems use the same band as the 5GHz WiFi (802.11a) at much higher transmit powers, yet there is no comment about schools being in the line of sight of these transmitters.

Many other pieces of equipment also use the 2.4GHz ISM band - wireless CCTV cameras, DECT phones, some walkie talkies, short-range video senders, and a whole plethora of other 'license-free wireless' devices. Why are people just concentrating on WiFi and not also investigating these other uses of the frequency band; many of which often transmit for longer bursts than WiFi, or don't use DSSS modulation techniques so have higher power peaks at particular frequencies rather than distributing the data and transmit power over a wider frequency spectrum.

If you ask me, it's just the teachers being scared the little darlings will find out what they're being taught is a load of cobblers!

Since when we have in UK GSM 800/1700?
Also, not only WiFi measures necessary power to transmit. Mobiles in GSM range did that from day one!
Point with many WiFi cells is partially wrong. Having more than one device with different SSID on same channel *WILL* cost more power output from the device trying to connect - as well as dropped connections.

Apart from that, you are right I was told that my aircon can be leathal...
And hairdryier (which I'm not using as I don't have enough hairs )

Cheers
Chris

 

[Ade B]

The classics teacher, who had taught at Stowe for 28 years, claims he suffered from nausea, headaches and a lack of concentration.

Surely the response of any traditionalist when confronted by progress?

Ade

 

[agatward]

Since when we have in UK GSM 800/1700?

The 'old' Orange 2G networks in certain locations are / were certainly on GSM800 - I remember them causing problems with certain other things in our labs at Nortel when I was there. I do not have figures about GSM1700 to hand.

Also, not only WiFi measures necessary power to transmit. Mobiles in GSM range did that from day one!

The point here was that both the AP and client on WiFi measure the required TX power. On GSM (unless it has changed since I last read the spec), only the handset does this, the base station always transmits at full power. This may well have changed though in order to help support more users per cell.

Point with many WiFi cells is partially wrong. Having more than one device with different SSID on same channel *WILL* cost more power output from the device trying to connect - as well as dropped connections.

I don't have this problem on the network I manage - but then again we use Aruba wireless kit with the wireless IDS stuff enabled so any rogue APs get the seek and destroy treatment

What would be interesting would be to get someone to do the calculations behind the energy absorption in soft tissue from, say, an 802.11g AP running on full power handling a full-data rate TCP stream at a distance of 1m, compared to either one of the XDA-style mobile handsets at a reasonable distance (500m?) from the cell base station, compared to the energy absorbed from a medical X-ray

Cheers,

Andy.

 

[columb]

You are right, there never was and never will be (design and whole concept of cells) GSM station with varied output power. There is no need to do that.
Different story with handsets but we have discussed that

I still can't agree to 800mhz for Orange in UK. I don't think anyone in Europe had ever license for 800MHz.
I know, that back in 2001 Alcatel, Philips and Ericssonn had plans for 800MHz upgraded GSM Faster GPRS? Or soemthing like this- can't remember.

Don't forget, that 900MHz is actually 890–915MHz!

Cheers
Chris

 

[smartbrabus]

I still can't agree to 800mhz for Orange in UK. I don't think anyone in Europe had ever license for 800MHz.

I believe you're correct there, Orange has always used the 1800MHz band for 2G.

Don't forget, that 900MHz is actually 890–915MHz!

880-915MHz and 925-960MHz, in fact

 

[columb]

I believe you're correct there, Orange has always used the 1800MHz band for 2G.


880-915MHz and 925-960MHz, in fact

In fact, you might be right

Sorry to be pain in the neck, but original GSM was only 890-915 I had to check that on Wikipedia as I don't really remember numbers that well:
(yes, I know about extended GSM)

http://en.wikipedia.org/wiki/GSM_frequency_ranges#GSM-900_and_GSM-1800

• GSM-900 uses 890–915 MHz to send information from the mobile station to the base station (uplink) and 935–960 MHz for the other direction (downlink), providing 124 RF channels (channel numbers 1 to 124) spaced at 200 kHz. Duplex spacing of 45 MHz is used.

In some countries the GSM-900 band has been extended to cover a larger frequency range. This 'extended GSM', E-GSM, uses 880–915 MHz (uplink) and 925–960 MHz (downlink), adding 50 channels (channel numbers 975 to 1023 and 0) to the original GSM-900 band. The GSM specifications also describe 'railways GSM', GSM-R, which uses 876–915 MHz (uplink) and 921–960 MHz (downlink). Channel numbers 955 to 1023. GSM-R provides additional channels and specialized services for use by railway personnel. All these variants are included in the GSM-900 specification.

Cheers
Chris

 

[smartbrabus]

Didn't mean to sound pedantic - just happened to have the 2007 UK spectrum allocations handy

Looks like we have a few members in the mobile phone industry here. I assume we can agree the mobile mast-cancer thing is the biggest load of scaremongering BS going?

 

[columb]

[FONT=Arial, Helvetica, sans-serif]OFCOM:

4. UK CELLULAR FREQUENCY RANGES[/FONT][FONT=Arial, Helvetica, sans-serif]
GSM 900 Frequency Range:[/FONT]
[FONT=Arial, Helvetica, sans-serif]Mobile transmit (BTx) 880 - 915 MHz
Base transmit (MTx) 925 - 960 MHz[/FONT]
[FONT=Arial, Helvetica, sans-serif]
GSM 1800 Frequency Range:[/FONT]
[FONT=Arial, Helvetica, sans-serif]Mobile transmit (BTx) 1710 - 1785 MHz
Base transmit (MTx) 1805 - 1880 MHz[/FONT]
[FONT=Arial, Helvetica, sans-serif]
Third-Generation (3G) Frequency Range:[/FONT]
[FONT=Arial, Helvetica, sans-serif]Base transmit (BTx) 2110 - 2170 MHz
Mobile transmit (MTx) 1920 - 1980 MHz[/FONT]
[FONT=Arial, Helvetica, sans-serif]BTx / MTx In TDD (Time Division Duplex) 1900 - 1920 MHz[/FONT]
[FONT=Arial, Helvetica, sans-serif]
The specific frequencies in use by the UK cellular systems may also be found at www.ero.dk under "Frequency Plans" and then "GSM Spectrum Use".[/FONT]


[FONT=Arial, Helvetica, sans-serif]Cheers[/FONT]
[FONT=Arial, Helvetica, sans-serif]Chris
[/FONT]

 

[columb]

I assume we can agree the mobile mast-cancer thing is the biggest load of scaremongering BS going?

Agreed.

Cheers
Chris