WiFi RF Transmit Power

[Just Mark]

After reading many threads in this forum and others about WiFi range and the best ways to extend it, I have to ask: Isn't the client device (thinking Phone/tablet/other mobile device) going to be the most likely limiting factor? Won't it have the lower gain antennas and less TX power (measured in EIRP) than most APs (being separate device or integrated into router/other edge device) on the market today?

Prior to me seeing the light in this wireless world we live in and taking the effort understand what it takes to get the coverage I needed/wanted, determine the location of APs, drill the holes, pull the cables, and mount the equipment, I had many dead spots in my house. But, not all devices experienced these dead spots the same. My laptop worked in the garage but my phone and tablet didn't. My wife's laptop wouldn't work in the Kitchen but every other device I tried did.

I'm saying that the client device has a bigger impact on range than any AP that I have ever had in my home. I could have an AP putting out 1KW (extreme exaggeration) of TX PWR, but it does no good if the client can't talk back.

 

[thiggins]

Yes, Wi-Fi is a two-way street. So client performance has a large effect on effective range.

That said, an experiment I preformed showed higher transmit power on routers can improve range.

http://www.smallnetbuilder.com/basi...228-an-experiment-in-wireless-power-and-range

 

[TonyH]

After reading many threads in this forum and others about WiFi range and the best ways to extend it, I have to ask: Isn't the client device (thinking Phone/tablet/other mobile device) going to be the most likely limiting factor? Won't it have the lower gain antennas and less TX power (measured in EIRP) than most APs (being separate device or integrated into router/other edge device) on the market today?

Prior to me seeing the light in this wireless world we live in and taking the effort understand what it takes to get the coverage I needed/wanted, determine the location of APs, drill the holes, pull the cables, and mount the equipment, I had many dead spots in my house. But, not all devices experienced these dead spots the same. My laptop worked in the garage but my phone and tablet didn't. My wife's laptop wouldn't work in the Kitchen but every other device I tried did.

I'm saying that the client device has a bigger impact on range than any AP that I have ever had in my home. I could have an AP putting out 1KW (extreme exaggeration) of TX PWR, but it does no good if the client can't talk back.

Is your router sitting on the best spot in your house? 1Kw? Wow! how big a battery do you want to lug around with your tablet?, LOL! I always used only router in my house w/o a big problem. As a side note I've been a HAM for over 60 years. Never used more than 100W TX power. I could talk to HAMs in EU with 0.5W flea power dangling at the feed point of beam on the tower.

 

[sfx2000]

Many folks aren't aware of this - but the Broadcom Linux STA driver (included with most Broadcom chipsets) interacts with the chip's Firmware RTOS, and inside there are regulatory Tx limits.

So while the driver might allow the user to turn the WL Tx power to 32 dBM, in actuality, if the regulatory limit is 23 dBm, that's as high as the chip will run... one can always turn the power down (to zero perhaps if that's desired)

Which probably explain's the results in the Wireless Power and Range article...

Not all OEM's run the chip at full power in any event... most do, but they're not required to (think power/heat considerations)

 

[stevech]

After reading many threads in this forum and others about WiFi range and the best ways to extend it, I have to ask: Isn't the client device (thinking Phone/tablet/other mobile device) going to be the most likely limiting factor? Won't it have the lower gain antennas and less TX power (measured in EIRP) than most APs (being separate device or integrated into router/other edge device) on the market today?

Prior to me seeing the light in this wireless world we live in and taking the effort understand what it takes to get the coverage I needed/wanted, determine the location of APs, drill the holes, pull the cables, and mount the equipment, I had many dead spots in my house. But, not all devices experienced these dead spots the same. My laptop worked in the garage but my phone and tablet didn't. My wife's laptop wouldn't work in the Kitchen but every other device I tried did.

I'm saying that the client device has a bigger impact on range than any AP that I have ever had in my home. I could have an AP putting out 1KW (extreme exaggeration) of TX PWR, but it does no good if the client can't talk back.

Yes, I preach that "unbalanced link" idea often in these forum. People think of WiFi as a one-way broadcast. I wish more APs/Routers would conveniently display the from-client signal strength and modulation rate.

Sad to see so many waste money trying to improve coverage with fancy routers (rather than adding an AP).

For any clinet to access device link, there are TWO coverage fried-egg patterns: inbound and outbound.

 

[sfx2000]

Yes, I preach that "unbalanced link" idea often in these forum. People think of WiFi as a one-way broadcast. I wish more APs/Routers would conveniently display the from-client signal strength and modulation rate.

Airports do

 

[L&LD]

After reading many threads in this forum and others about WiFi range and the best ways to extend it, I have to ask: Isn't the client device (thinking Phone/tablet/other mobile device) going to be the most likely limiting factor? Won't it have the lower gain antennas and less TX power (measured in EIRP) than most APs (being separate device or integrated into router/other edge device) on the market today?

Prior to me seeing the light in this wireless world we live in and taking the effort understand what it takes to get the coverage I needed/wanted, determine the location of APs, drill the holes, pull the cables, and mount the equipment, I had many dead spots in my house. But, not all devices experienced these dead spots the same. My laptop worked in the garage but my phone and tablet didn't. My wife's laptop wouldn't work in the Kitchen but every other device I tried did.

I'm saying that the client device has a bigger impact on range than any AP that I have ever had in my home. I could have an AP putting out 1KW (extreme exaggeration) of TX PWR, but it does no good if the client can't talk back.

Yes, the client device does have the biggest impact. But not for the reasons you may think though.

http://www.snbforums.com/threads/fo...ilable-v17e8-v18b1.18914/page-192#post-261222


When a specific client device doesn't work where others do; it is just bad design and/or poor components and/or bad drivers (or driver defaults). There are many examples of these types of devices, but most people don't have the fringe conditions to show them at their worst.

 

[thiggins]

Thanks for the info about baked-in power limits, SFX.

 

[stevech]

baked-in power limits... rooted in cost to produce power versus modulation order. 802.11b is always highest power by far, for the same hardware has to "back-off" power by 3-6dB in the fancier OFDM modes. To preserve waveform quality (rho), else the transmitted signal is distorted and net throughput suffers.

So a WiFi product maker knows what rho the WiFi alliance wants, and manages the power amplifier to meet the rho goal.

The user interfaces that offer 100mW at high modulation rates are fooling the the user. Typically, more like 30mW at high modulation orders, and 60-100mW at lower ones.

But! The path length losses are many tens of dB, so the dB difference between 60 and 100mW is almost negligible in terms of range improvement. RF signal propagation is a logarithmic world.