I have done some RF maps for my area. I would be crazy happy with AP and a CPE that could use the first adjacent channel space (it adds another 5 channels for some areas where I only have a few channels fully open). I would love for the radio to have adjustable channel widths, even if they have to be continuous. Say 4x6mhz down and 1 or 2x6mhz up. Depending on the tech used, that could be anyplace from 12 to 48mbit data.
On Thu, Oct 7, 2010 at 6:54 PM, Brian Webster <[email protected]> wrote: > I have been reading through the White Spaces rules and it occurred to me > that if we could get the manufacturers to get away from half duplex radios > running on the same frequency, WISPs could actually use the first adjacent > channels to existing broadcast contours. How is this you ask? Well in the > first adjacent channel you can run up to 40 mw with a 0 db non detachable > antenna. If a person were to put up a receive only site with a commonly > available 15 db TV style antenna, you would be surprised how far the signal > will travel in these lower frequencies. The unlicensed devices that can > operate in the first adjacent channels can only use channels 21 and up (with > the usual exceptions like channel 37 and the reserved channels for wireless > mics). If you do not transmit through the 15 dbi antenna there is nothing > against this in the rules. A manufacturer could produce a radio that has two > separate radios in the same unit. One for transmit at the 40 mw level with > no external antenna and another that receives only with an antenna port > where you could attach a common dual bowtie TV antenna that has 15 db gain. > This would create a balanced path plus it would have the effect of 12 MHz > bandwidth because you could have separate transmit and receive frequencies. > > > > One of the big advantages to TVWS spectrum is the decrease in free space > loss and the reduction in the losses through trees and other vegetation. > Compared to the 2.4 and 5.7 GHz bands the increase in gain because of free > space loss is between 15 and 20 db! Add a 15 db gain antenna and you can see > where a 40 mw signal can now propagate quite far. > > > > I have created some RF propagation maps on a random site in central NY near > Ithaca in the Finger Lakes Region. In this Google Earth file (attached) > there are propagations showing the range of a 40mw configuration like I have > described as well as plots for the fixed wireless power levels using the > same tower location and heights. I threw in a 2.4 GHz plot on the same tower > for comparison as well as a fixed wireless power level study using TV > channel 2. Take a look at the file. You will need to turn the different > layers on and off to see the different characteristics of each channel and > configuration. There are notes with each plot telling the parameters used. > Receive signal level was assumed to be -90 dBm. > > > > This should excite every WISP as to the possibilities for everyone to use > this new spectrum! Let’s just hope the manufacturers start to understand the > possibilities and produce radios to take advantage of this. > > > > Thank You, > > Brian Webster > > www.wirelessmapping.com > > www.Broadband-Mapping.com > > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
