1.5Km wireless bridge with 2 cpe510

Hello.
I made a wireless bridge with 2 cpe510 v3 with OpenWRT SNAPSHOT r10551-d616b2c906 at a distance of 1.5km.
The problem is that the connection speed is only 6Mbps and often disconnects.
(It would be useful in "Associated Stations" to see how long the connection has been established)

These are the settings:
** Access Point (WDS)

config wifi-device 'radio0'
        option type 'mac80211'
        option hwmode '11a'
        option path 'platform/ahb/18100000.wmac'
        option country 'IT'
        option distance '1500'
        option channel 'auto'
        option htmode 'HT20'
        option legacy_rates '0'

config wifi-iface
        option device 'radio0'
        option mode 'ap'
        option wds '1'
        option ssid 'NOME'
        option network 'lan'
        option encryption 'psk2+ccmp'
        option key 'PASSWORD'
        option hidden '1'

** Client (WDS)

config wifi-device 'radio0'
        option type 'mac80211'
        option hwmode '11a'
        option path 'platform/ahb/18100000.wmac'
        option htmode 'HT20'
        option country 'IT'
        option legacy_rates '0'
        option distance '1500'
        option channel 'auto'

config wifi-iface
        option device 'radio0'
        option mode 'sta'
        option wds '1'
        option ssid 'NOME'
        option bssid 'XX:XX:XX:XX:E8:80'
        option network 'lan'
        option encryption 'psk2+ccmp'
        option key 'PASSWORD'

How can I improve speed and stability?
Thanks.

with 5GHz is there a difference between IT and US?

A Wi-Fi site survey might help, check which channel(s) are your best options (lowest noise).

Use a LASER pointer to position the APs.

AP height should be set according to:

The earth curvature doesn't play any role over such a short distance.
http://earthcurvature.com/

Good Luck! :slight_smile:

1 Like

Also, unless you're sure of the distance, definitely add a few more meters (~100m) to your distance optimization setting. If you underestimated the 1500m, that could cause an issue.

1 Like

the issue is more than obvious. either CPEs are not aligned to each other or there is some nasty obstacle

1 Like

I have no idea, but if I use a TP-Link TL-WN7200ND that transmits up to 30 dBm in 2.4Ghz, if I choose Argentina, I can only use up to 20 dBm. While with US I can use those 30 dBm.
I suspect that the devices are not perfectly aligned.
I also have a CPE210 that if I use the country AR (Argentina), it is reduced to only 10 dBm.
It may be that your device does not use maximum power.

In regards to the regulatory domain settings there is only a single viable option, the one in which jurisdiction you're setting up your wireless link - even more so with outdoor devices and operating in the 5 GHz band.

The US (FCC) allows different 5 GHz channels than Italy (ETSI) and also uses different detection patterns for DFS events, while your signal can actively distort (civilian and military) weather radar (the primary, licensed user of this spectrum) readings for 40-60 km of range and may also annoy cell phone providers. These users will notice - and they will take action, depending on the severity of the interference within hours, and they will come with gifts hefty fines in the 4-5 figure range.

4 Likes

I added 100mt to the distance.
I have tried several channels and only works with 44 (5.220 GHz).
With 40Mhz it doesn't work.
The speed does not change.

How can I enable Short GI?
Is there a way to know how long the bridge has been UP?

I'll check the alignment and then I'll let you know.
Thank you

You also probably want to specify channel rather than using auto and might want to add noscan.

Hi,

I am not an expert, but why would you use 5G if 2.4G has much greater range to begin with? The wavelength plays a role here, not just radiation power. Without going too deep into theory, the lower the frequency the greater the communication distance, while the higher the frequency the better obstacle penetration. For example, GSM cellular phone only uses .5W with 900MHz for up to 30km signal range.

Back in 2007 I worked with a 29km WiFi(802.11g) bridge with 2 Yagi antennas and 50W amps (about 130db total)
We used a laser to point the antennas properly.

I would switch to the 2.4GHz and use narrow beam directional antennas on both sides. Narrow beam is important for range and to minimize interference. Don’t forget line of sight.

Edit:
1.Amp Example for your case.
2.Antenna Example for your case.
Obviously, to achieve 2x2 you will in fact need 2 sets on each side.

From what I know in Italy it is possible to build wireless bridges in public areas only with 5GHz.
I'm wrong?

Is there a way to know how long the bridge has been UP?

Thanks.

-89 dBm is the problem. There is either misalignment, obstructions, or just overall bad radio performance, or the driver is not working properly. I have no experience with that particular model to know which of the above it might be, but you're not going to have a reliable link with signals in the -80s. Really you would want to be around -70 dBm.

2,4G is in HAM radio range, you will need to obtain a radio license to operate it over 0.01W. I do not think anyone will blame you for testing it and you can get the license after you test it and like the results.
Try switching to an external antenna for your bridge devices to a higher gain (read - 20~25dBi) before you go too deep into expenses. The stock is claimed to be only 13 which is not bad but still weak.
Edit: as long as you do not try to cook your neighbor with 50W transmitter :smile:
To have an idea of how much more power you need, try this calculator. Estimate the power required for 5 and compare to 2.4.

For link uptime, you can use an external tool to monitor the FE (far-end) device availability time. There are many solutions to do this.

The standard channels are not in the Amateur Radio Service. That service forbids commercial or encrypted operation of any type.

Operation with an external power amplifier of any sort, not to mention 50 W, almost certainly requires a (commercial) station license and potentially operator licenses.

1 Like

Jeff,
In general, the 2.4 WiFi frequencies are in HAM bands and shared with a tremendous amount of other radio devices, including RC toys, Bluetooth devices and many more. Some of those ranges can be partially prohibited in certain countries. I found this chart pretty useful to lookup stuff once.

Upper 5G bands amplified to 4W are legal in there according to this.
If I understand correctly, the topic starter uses lower channels with a 4W transceiver which is illegal to start with. Yet I do not think anyone will be chased for a 4W transmission.
50W microwave energy is not safe to use without understanding what it does, not recommended and not required for this setup, but 4~5W amp with narrow beam antenna (18° h/v or less) will probably make the required cut.

Edit: Even if licensing is required, unless the frequency is in use, obtaining a license for private (non-commercial use) is usually painful but doable task. Bureaucracy is different in every country, generally it will require equipment inspection and measurements which are not free.

Edit2: Found this poster for US HAM map.

I'm back.
I checked the alignment, there are no obstacles but the speed is always 6Mb.
The only channel that works is 44 (5,220 GHz).
The transmission power set to "auto" is 9dBm, if I try to set it to 13dBm (19mW) Tx-Power is always 9dBm, why?
tp-power1
Thank you

Check with iw phy phy0 channels and look for something similar to

* 5220 MHz [44] 
	  Maximum TX power: 20.0 dBm
	  Channel widths: 20MHz HT40- HT40+

Do you have 9dBm there? If yes, I would play with country selection.

Edit: curious what iw reg get shows.

tp-power2

See photo

thank you, but there is no need to use photo to display text

Signal -89 is not good. Do you have true line of sight, no trees or anything?

Some drivers report 6 MB regardless of the real speed. You could install iperf3 at both ends to test actual bit rate.