Posted: Sat May 09, 2020 14:58 Post subject: Assign one antenna to virtual AP
Hi,
I would like to ask if its possible to assign one antenna (probe antenna) to a virtual AP which is created my DDWRT and one antenna (beam antenna) to WAN (Client-BG).
Background of that Question is:
I would like to supply our gardenshack with Internet Wifi. There is no cellphonecoverage, but approxemately 100 Meters away in sight is a WiFi I can log in.
Using a TP-Link TP-WR842 with removable antennas i can login, create a local WiFi using virtual AP and supply all local devices with Internet. But the connection is instable and sometimes poor.
I have here a Yagi (10dBi Alfa AYA-2410 WLAN YAGI Antenne (Richtantenne) outdoor 2,4GHz) and I am wondering if I could use that antenna for logging into the faraway Wifi and use the probeantenna for local Wifi?
Joined: 04 Aug 2018 Posts: 1447 Location: Appalachian mountains, USA
Posted: Sat May 09, 2020 15:48 Post subject:
I actually have no idea what the proper answer is to your question from a dd-wrt point of view, but my guess is that no, you can't assign antennas that way. Might depend on your router model and build though.
What's more interesting is that it might work anyway to just connect one antenna port to the yagi and leave the others with their usual little omni antennas, provided you have single-user beamforming enabled. It all depends on the beamforming algorithm used, which I can't begin to guess, but there's a possibility that the algorithm will sort out that there's a nice signal available if it weights lots of the yagi's signal with tiny bits of signals from the other antennas to cancel interfering signals sneaking into the yagi's sidelobes. It's worth just trying it.
Aiming the yagi could be the hard part, and I suspect that if you know enough about antennas to know what a yagi is, you probably know to set it up with no metal anywhere around it except possibly a vertical mounting mast and to keep its cable short and unkinked.
In any case, the quirk here that I wonder about is what about the 5 GHz band, where the 2.4 GHz yagi will look to its Tx port more like a capacitor (I think... I'm rusty) than an antenna. Most of the intended 5G transmit power from the yagi's antenna port will be reflected back into the transmit electronics, much as if there were nothing attached to the port at all. So the scheme kind of assumes the 5GHz wifi driver is robust enough to be OK and reasonably functional with a missing antenna. Probably it can handle it fine, considering the squawks that would come from customers if their routers fried every time an antenna was missing or not connected quite right. (Don't try the missing-antenna trick with a high-power transmitter though!)
Using dd-wrt I'd be inclined to use Client Mode with the 2.4G yagi link as the WAN connection and with the 5G wifi system then used to connect your client devices. I use a setup like that, without yagi, to connect a router to hotel systems when traveling just to have my vpn (one in the router vs a client on every phone, tablet, and computer in the room) and firewall in the picture, the firewall because I figure I can't trust the competence with which the hotel's system is configured. There's a reasonable wiki tutorial on setting up client mode, though I forget what it's called. _________________ 2x Netgear XR500 and 3x Linksys WRT1900ACSv2 on 53544: VLANs, VAPs, NAS, station mode, OpenVPN client (AirVPN), wireguard server (AirVPN port forward) and clients (AzireVPN, AirVPN, private), 3 DNSCrypt providers via VPN.
Thank you for you very valuable reply.
I will test the setup enabling single-user beamforming, and my device is 2.4Ghz able only (The faraway Wifi has also only 2.4Ghz anyway and for 5Ghz the distance is too far I think).
I can fully understand your reasons and like your setup for hotels Wifi. Using the router as VPN Client, you also can limit access to your VPN-Server to MAC Adress of your router. (a man-in-the-middle could still catch your routers MAC though).
Using your setup you can benefit from your homecountrys IP (maybe youtube-blocking), your own firewall-setup, and you only need to configure one device with hotels password instead of x devices.
I really like that!
Joined: 04 Aug 2018 Posts: 1447 Location: Appalachian mountains, USA
Posted: Sat May 09, 2020 17:37 Post subject:
bul wrote:
Thank you for you very valuable reply.
I will test the setup enabling single-user beamforming, and my device is 2.4Ghz able only (The faraway Wifi has also only 2.4Ghz anyway and for 5Ghz the distance is too far I think).
I'll be really curious to hear whether this works! (I assume you have a yagi specifically made for 2.4G wifi use, as yagis are narrowband antennas and cannot be used far from the intended frequency range.)
Quote:
I can fully understand your reasons and like your setup for hotels Wifi. Using the router as VPN Client, you also can limit access to your VPN-Server to MAC Adress of your router. (a man-in-the-middle could still catch your routers MAC though).
No, my vpn client. I have the wifi's encryption to get from my computer or phone to the router -- way safer than the open-wifi setups used at most hotels now with captive-portal login schemes that protect them but not you -- and from there the vpn encryption protects from MITM issues (important for hotels) as my data goes to/from an AirVPN server far away. Even if somehow I connect to a rogue wifi hotspot, the encryption means they can't actually do me any harm, as far as I can see.
Quote:
Using your setup you can benefit from your homecountrys IP (maybe youtube-blocking), your own firewall-setup, and you only need to configure one device with hotels password instead of x devices.
I really like that!
best regards,
bul
I don't try to bypass streaming blocks, and it's hard to do that reliably anyway, as the streaming services fight hard to recognize and block vpn IPs. But the other benefits are just as you say, and the MITM safety is perhaps the biggest motivation. The downside of the approach is that I find I am able to connect successfully to only half or so of hotel systems, even though my router clones my phone's MAC and my phone has already logged in once to get things started. I've never been able to sort out why the other connections fail. _________________ 2x Netgear XR500 and 3x Linksys WRT1900ACSv2 on 53544: VLANs, VAPs, NAS, station mode, OpenVPN client (AirVPN), wireguard server (AirVPN port forward) and clients (AzireVPN, AirVPN, private), 3 DNSCrypt providers via VPN.
First I connected to the wifispot using 2 omniantennas (my device can only have 2 antennas connected).
Then removed all two connected antennas and as expected the signalquality went down.
Then I connected the yagi only on one of the two antennaports and immediately the signalquality rised to a level i never had before.
Then i connected one omniantenna on the remaining antennaport and the signalquality didnt change.
Interestingly I did not find an option for single-user beamforming enabled setting, But its enabled by default, so I think its ok. Maybe this option does not exist on my device.
Joined: 04 Aug 2018 Posts: 1447 Location: Appalachian mountains, USA
Posted: Sun May 10, 2020 19:38 Post subject:
bul wrote:
I checked and it seems to work like a charm.
First I connected to the wifispot using 2 omniantennas (my device can only have 2 antennas connected).
Then removed all two connected antennas and as expected the signalquality went down.
Then I connected the yagi only on one of the two antennaports and immediately the signalquality rised to a level i never had before.
Then i connected one omniantenna on the remaining antennaport and the signalquality didnt change.
Interestingly I did not find an option for single-user beamforming enabled setting, But its enabled by default, so I think its ok. Maybe this option does not exist on my device.
Thank you!
Bul
Excellent! I do suggest leaving the omni on the "other" port, if it makes no obvious difference to the quality of your hotspot connection. It should keep the transmitter electronics happier, and you'll probably get better connectivity for your own devices.
And you probably guessed correctly: Indeed, the beamforming options are not there for all routers. I think the actual beamforming is done in either the wifi chipset (probably) or the driver provided by the manufacturer. Not really something dd-wrt is going to get into itself. So if the router maker didn't use a beamforming-capable chipset, you won't get an enable button for it.
It's also the case that there are ways to use multiple antennas other than those that are properly called beamforming. I'm rusty now, as it's been decades, but at one point in my life I was actually a modem engineer. I've also done my share of designing multi-antenna combining systems. It's actually a huge field with lots of ideas floating around in it. _________________ 2x Netgear XR500 and 3x Linksys WRT1900ACSv2 on 53544: VLANs, VAPs, NAS, station mode, OpenVPN client (AirVPN), wireguard server (AirVPN port forward) and clients (AzireVPN, AirVPN, private), 3 DNSCrypt providers via VPN.
You mean a virtual beam antenna by using an phased array of omni antennas?
Such a device would be awesome! Automatically aligning the beam to the source, but as its military technology its quiet expensive I would guess...
Joined: 04 Aug 2018 Posts: 1447 Location: Appalachian mountains, USA
Posted: Mon May 11, 2020 15:37 Post subject:
bul wrote:
You mean a virtual beam antenna by using an phased array of omni antennas?
Such a device would be awesome! Automatically aligning the beam to the source, but as its military technology its quiet expensive I would guess...
Not just military these days, as advances in DSP speed and reductions in the cost of computational hardware have gone so far as to make it practical to handle variations on these approaches in pretty ordinary systems, like cellphone base stations. At a more basic level yet, even in some phones and routers and such. This is one of those areas where we can thank the military labs and military funding of universities for cooking up a lot of the algorithmic approaches early on and the mobile-phone industry for driving the development later of cost-effective hardware. Put the two together and magic happens! _________________ 2x Netgear XR500 and 3x Linksys WRT1900ACSv2 on 53544: VLANs, VAPs, NAS, station mode, OpenVPN client (AirVPN), wireguard server (AirVPN port forward) and clients (AzireVPN, AirVPN, private), 3 DNSCrypt providers via VPN.
