Hi all,
we're using since some years ePMP1000/2000 always with 20 Mhz channel.
Recently we're reaching saturation in a lot of ePMP2000 AP when they have about 30-40 SM and more...
Throughput can't be more than 55-65 mbps using 20 Mhz channel.
I'd like to know if someone tried 40 Mhz channel in these situations and if we really double performances or just increase a little bit...
We have an AP were we did just the opposite, went from 40Mhz to 20Mhz. The reason for the change was simply due to interference / crowding. The AP had/has about 37 customers on it and an uncapped subscriber radio could hit about 110+Mbps during low usage times of the day. At 20Mhz I think around 70Mbps is probably about has high as I've seen. The graph below is the total frame time used, you can see that it was about mid November when we changed from a 40Mhz to 20Mhz channel.
Your results may be better or worse depending on the quality of your connections. I believe the requirement for any given MCS rate is about 3dBm more at 40Mhz than 20Mhz so while some of my customers got slightly better MCS rates and RSSI your's will get slightly worse. So depending on the quality of your current connections going to 40Mhz channel might make your problems better or it might make them worse.
Then there is noise/interference ... wider channels mean that not only are you now open to even more interference but you are also spewing out more and increasing the likelihood of self interference ( GPS Sync only stops your AP's from interfering with each other it can not prevent your customer radios from interfering with other AP's or other AP's from interfering with them).
We would love to do 40Mhz everywhere but in less rural areas Interference (self and other) makes it impossible and in the very rural areas the customers being much farther from the AP's and needing every last dBm forces us to 20Mhz channels.
Thank you for your reply... that's a very interesting post!
I think I'll get a try in a low interference area and I'll see how it works!
Regards,
Paolo
@paolo-pftech wrote:
Hi all,
we're using since some years ePMP1000/2000 always with 20 Mhz channel.
Recently we're reaching saturation in a lot of ePMP2000 AP when they have about 30-40 SM and more...
Throughput can't be more than 55-65 mbps using 20 Mhz channel.
I'd like to know if someone tried 40 Mhz channel in these situations and if we really double performances or just increase a little bit...
Many customers have decided to go for 40MHz channels and they ejoy today even up to 150Mbps out of AP in 75:25 TDD mode on downlink with 50+ clients on AP. Most of them had to introduce frequency reuse in their networks (ABAB) to save on the spectrum usage - but it was well worth it. Having said that, there will be always some areas with extreme noise where only 20MHz would survive but many can really enjoy 40MHz adavantage - while still saving spectrum due to GPS sync.
The picture below (sent by one of our happy customers) shows 55 Elevated Nano Loco's running on 40MHz 75:25 TDD traffic. This is not maximum we've seen but already nice enough so share! :-)
55 elevated nanostation loco M5 units is is obviously a dense urban environment where the (very low gain) CPE are very close to the AP. This isn't an apples-to-apples for most installations probably.
In my own environment with customers from 1~7 miles from an ap we often see similar results between 20 and 40Mhz channel widths where noise is an issue for reasons already stated. For close-in sites 40Mhz tends to provide a lot more bandwidth.
With 4.4.1 and short guard interval we have seen peaks closer to 80mbit on busy 20mhz APs.
