North Queens TV White Space Trials
Longer Term Tests
Most of our propagation tests have only been of a few hours duration so we have been anxious to run some longer term tests to look at things like the seasonal changes due to variation in vegetation, climate and variations in the noise floor.
For our first test we have select test 22 to the Mersey Tobeatic Research Institute, it is one of the longer links at 9km with at least 1/2 of the direct signal path through the trees a challenging link that none of the technologies currently available to unlicensed wireless internet service providers would be capable of doing.
More details of the link can be found at the test report page.
We are confident if we did make these changes that we could get the link speed close to it's maximum speed of 16Mbs UDP or 11-12Mbs TCP and have already experienced this under certain climatic conditions.
The equipment we are using is capable of operating in dual channel mode when approved by Industry Science and Economic Development Canada this will enable us to nearly double the throughput to 20-24Mbs at no additional cost, unfortunately the is nowhere in the area we can economically connect to the internet at that speed.
Technical Details of the Initial Installation
The specifications for the equipment we are using can be found here
More details of the link can be found at our initial link report here
After semi permanent installation of the equipment we are getting the following statistics
Base Station Antenna Height 14m
Mersey Tobeatic Research Instituted Antenna Height 7 meters
RSSI -78dBm, Noise Floor -103dbm SNR24
Data Rate MCS 4 Raw data rate 10Mbs UDP or ~6-7Mbs TCP
Earlier speed test were conducted using an LTE connection to the internet and with the weaker signal were 4Mbs TCP up and down in other words symmetrical
We are now connected to a DSL line which is limiting our speed to 5Mbs down and 0.5Mbs up
Tests show the latency between our equipment is less than 2ms but the available internet sources add 20-60ms.
Early Results from the Long Term Tests
This test was started in early December long after all the leafs where gone and we didn't expect much variation in signal strength, we were wrong.
Over a one week period we have seen a variation in signal strength of 12dBi over a 9km link fortunately higher than our initial test. The weather has been a significant factor we have seen the following conditions
Cold -15C windy blizzard conditions signal -70dBm
Heavy snow fall no wind -5C signal -78dBm this increased to -74dBm after a wind came up
Calm high humidity and rain temperature around freezing, signal -82dBm
Rain windy humidity 97% +12C signal -81dBm
Our current theory is that unlike conventional links where most of the signal path is through free air a lot of the signal path is through vegetation specifically evergreen trees. A significant part of the signal path is skimming through the tree tops where a build up of moisture or snow would have a noticeable affect. We suspect that when we had temperatures around zero there was some ice forming which together with the high humidity/freezing fog lead to the highest attenuation
We will be watching this link with considerable interest, we had assumed we would experience maximum signal attenuation in early summer just after the leafs are fully out perhaps this is not the case with this particular link.
We now have longer term data that can be viewed on the Climatic Variations web page