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Long distance WiFi: how (not) to build one

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Avatar for Geri
Written by   86
3 months ago

Recently i started to prepare against internet outage. My goal was to keep in touch with my friends from my area. The most logical step was to create a WiFi based network. Therefore, i have decided to build a long distance WiFi network by using cheap junk hardware. In this article, i will explain how it went, why certain solutions failed, and what is the proper strategy to carry out this plan.

How we did networking in the early 2000s

In the early 2000s, long time before unlimited internet access was a thing, the internet connections were limited by a monthly 300-400 MByte traffic limits. This was too small even by then, even if someone just wanted to browse news sites (even if websites back then was only using 1-2 MByte traffic maximum per page). However, internal traffic was free, therefore people within the same ISP was able to send data to each other without limitations. By using software such as IRC, DCC, DC++, people was able to chat to each other, organize events, and exchange pictures, music, movies, and other type of data to each other. Every city and area had its own servers, where people were able to gather. This era ended by the appearance of the virtually unlimited internet traffic era after 2007.

Its crucial to have a fallback

People take internet for granted, however, its wise to have a backup plan how to keep the connection with local friends in your area in the case of a larger internet breakdown, or a natural disaster. This maybe sounds strange from the aspect of a modern era - where people might not even know their neighbors, and trying not to reveal themself in online chatting. However, if there is no internet access, people will have to connect to each other, if they want to exchange information. In the case of difficulties, it could be necessary to maintain a local network, where your friends can connect, and where everyone can communicate to each other easily. The same type of software showcased above (irc, dcc, dc++) can be easily used for this communication, but more smartphone-centric solutions also exist - some don't even requires a central server to run. In this article, however, the software side of the things will not be discussed, and only the hardware side of the things will be investigated.

First thoughts

The hardware used for modern communication networks, is WiFi (Wi-Fi). From the smartphone to the computer, through smart TV and household appliances, they use a WiFi network to communicate to each other. WiFi has various implementations, versions, but the newer ones are always backwards compatible with the older ones. As WiFi is an integrated and widely used method for communication, its logical to use that for a project like this.

Various forms of WiFi

WiFi can communicate at 2.4 GHz and on the 5 GHz range. The WiFi first used the 2.4 GHz frequency, and later on, they have added an 5 GHz variation to it. The problem with the 5 GHz frequency is that higher rated frequencies travel less further, so an 5 GHz Wi-Fi can achieve less distance from the same power envelope. The 802.11b is the 2.4 GHz variation of WiFi, and everything is compatible with it. 802.11a is the 5 GHz variation of WiFi. Later on, they have added various other standards which increase the data bandwidth both for the 2.4 GHz and the 5 GHz variation, called WiFi 802.11g and 802.11n. In this test, i will use the 802.11b for maximal compatibility, at the basic 11 MBit/sec standard rate (limited to 1 MBPS symbol rate for maximal distance and compatibility).

Drawbacks of WiFi

WiFi is primarily a centralized protocol. The center of a WiFi network is a device with strong antennas - typically a WiFi capable router. Each of the devices connect to this WiFi network, and then every communication is going through this WiFi device. The two WiFi device cant directly send data to each other on a hardware level, the connections are always handled by the WiFi router. The protocoll could be modified to have a more decentralized WiFi network in theory, however there are no steardy and standardized implementations of anything like that so far, therefore any attempts for this project must follow the original, standard, centralized WiFi conception.

Lets check what i have

Last time when the ISP gave us a cable modem, they gave us a model which also had internal WiFi support. This cable modem was built by Arris, and it was made in China. By using my phone, i have checked the signal strength. Instead of using specialized programs, i have just joined to the network, and checked where the mobile is unable to connect any more. Indeed, the signal dead on the end of the backyard on my phone.

Lets check my drawer

My drawer contains my old 14 year old WiFi router, which is very dinosauric. However this router has a detachable antenna. By searching a bit, i figured out the name of the connector: its called an SMA connector. This connector is a standard, and various routers have it, and various form factor and size of antennas are available. The old router itself is too weak for anything interesting, it can't even cover the house with a signal, therefore, it went back to the drawer.

LB-Link wifi hunter

Once i bought a wifi hunter from LB-Link. This is actually an outdoor directional antenna with integrated Wi-Fi chip, and it has two USB connectors. The target audience of these wifi hunters are truck drivers and so on, but i figured out that i could use it as a hotspot. In linux, i have added the hardware. It was tricky, because it needed its own proprietrary drivers to work. After that, i configured it as a hotspot with the help of hostapd and dnsmasq. Indeed i was able to connect to it, so i went outdoors with my phone to check the signal. The signal was died off after just 3 houses. My antenna was in a street-front room, halfway height. The result were not good, i don't considered this antenna a good choice, but if someone just wants to hunt for an open Wi-Fi, then it could of course do the trick.

Lets search for a super router!

After searching on the internet, it turned out that there are routers with 6 antennas, however, these are typically not detachable. After a while, i was able to find routers with detachable antennas, but they were super expensive. These routers are usually above $400, but luckily i was able to find one model. It was called Asus WRT-AC3200, and i was able to buy it for $70 used. I was very happy to have this router, and i expected a lot from it. As in theory, it had one 2.4 GHz and two 5 GHz newer type of WiFi. What could go wrong?

Asus AC3200 the manure router

After the AC3200 arrived, i quickly noticed that only three of the antennas was able to communicate at 2.4 GHz, the rest of the antennas was 5 GHz only. Asus did a little cloudy advertisement, making people to think that all antennas are capable of the 2.4 GHz, which is basically false advertisement. After i have setup the router, i quickly went around to check the signal quality. The signal was actually WORSE than with the Arris router of the ISP. As the router were idling on my desk, it suddenly crashed, and the router was not able to boot any more... I was only able to access the firmware upgrade menu, where i have tried several firmwares. The router was able to boot, but it was not able to initialize the 2.4 GHz chip any more, which always caused a hang after a while. I was able to get it working once again, but shortly after that, it rebooted on its own, and the operating system was not able to boot up on it ever again. The seller refused to refund my money, claiming it was worked for him, and indeed, initially, it was working. I dont blame the seller because i having the same experience with Asus products again and again, everything they made is barely better than pure shit. After this, i was trying to figure out how to try to repair this router. One of the sides of the router became cold, and another was very hot - which made me think that maybe the voltage regulators for the chip have dead. The router suddenly vomited a sparks out with a loud creek, and after some smoke came out, i decided to throw this junk to the garbage.

Giant thicc antennas

I have bought two giant SMA dish antennas from old-stock, called TP-Link TL-ANT2414A. The seller only had two of them, he was cleaning out his old-stock hardware. I got the two antennas for about $60. The size of the two antennas are 25x25 centimeters which makes it quite giant. As the Asus died, i had no hardware to test them. The antennas were brand new, they came with their original flyers inside the box. There was some of the TP-Link routers featured as compatible models, where the claimed that those routers will work very reliably with these antennas. The biggest and strongest router compatible with these antennas were the TP-Link 1043ND, which was also old, however, had three SMA antenna ports, and it wasn't too expensive either.

TP-Link 1043ND

The TP-Link 1043ND is a cheap router with three SMA antennas, i was able to buy this router for about $25. The router is configured to output only 18 dbm (0.06 watts) by default. I have installed a thirdparty firmware based on OpenWRT which allowed me to set higher dbm settings. The legal limit in the European Union is 20 dbm, althrough the firmware allows to select 23 dbm, which is 0.2 watts. This is the official maximal output of the Wi-Fi chip inside the router, but if the users sets Bolivia as the country, values up to 27 dbm can be selected. This means 0.5 watts in theory, but i am prety sure the signal amplifiers of the router are unable to generate this much of output power for the signal. The maximal distance of the devices from the router must also be specified, because by default, Wi-Fi routers will use signal timings incapable to be acknowledged by the router if the distance is more than a couple hundred meters. Luckily OpenWRT allows to set this to any number, so i set it to 9999 meters.

Setting up the antennas

I have put the antennas up, set the output to 23 dbm, and later one i have tried it with 27 dbm as well. I have set the antennas into direction, and started to walk. I have placed the router multiple places - below the rooftop (but within the house), in the center of the room, below the center of the room, and observed where the signal dies. The best results where if the antennas were placed in the rooftop, and the dbm was set to 27 dbm.

The problem with the antennas

The antennas are really annoying. They are heavy, but not too heavy. The cables are rigid, and they can simply drag the antennas down. There were several occasions when it fell at me, as i was setting up the experiments. One time the antenna caused me severe injury as it fell on my hand, leaving a large scratch, and my arm started bleeding. The antennas have no poles to connect to, so i have used four old cornering irons (fixed hinges) to keep them standing up. The cables are very dodgy in quality, and they always started to unscrew themself from the router. These antennas are very shitty design. I haven't opened them yet, but i don't expect any miracles inside them either.

The results

The phone saw the router 5 houses away, when i have set the router to 27 dbm and put the antennas below the rooftop, however, the phone was not able to send data back to the router, and it was not able to obtain an ip address even just after two houses away. This means that the device which wants to connect to the router, must also have stronger directional antennas, to be able to communicate with the router. Even a strong router working above legal boundaries and far above its own specifications is not enough to achieve large distances with WiFi, if the devices are placed in the house, other devices are around, and/or if the phone is inside a house. The signal instantly died even if i tried to connect from the garage, but it worked without problems from the garden.

Other problems

TP-Link 1043ND has a very short coord. For some reason, TP-Link thought it will be a fantastic idea to equip the wall adapter of their flagship router with a pathetic 60 centimeter cord. This makes it impossible to put the router into random places without using coord extensioners. The router boots very slowly, as it has an anemic 400 MHz MIPS processor, which is too slow to execute the Blood-Steve quality shoddy linux scripts required for setting up the network. The stock antennas on the 1043ND are very pathetic, they add three but all of them is only 3 dbi, luckily i kept the antennas from the Asus, which are about 15% stronger, so i have added to one of the antenna places. The router also forgets the dbm settings, and always fells back to 23 dbm after a reboot. Fantastic.

Configuration errors

Originally the router firmware only allows 254 ip addresses to be shared on the network, with the netmask 255.255.255.0. After i have set this to 255.255.0.0 and explained the DHCP server that it can allow 65536 peers, the router crashed, and was not able to come online ever again, until i have pressed a long reset on it, restoring the settings to defaults. Next time i have restricted the number of clients to 3000, which caused the DHCP server just crashed in the middle of an ip address inquiry.

Then i have tried the number 1500, which worked, but every DHCP address acquiration took like half a minute. The number i settled on, was 1200, which only takes about 10 seconds. Of course, 1200 person would never connect to this network, but if someone joins to the network with a lot of his smart craps, the original 254 ip address could be a little bit short. The 1200 should be okay for every purpose, maybe i will later decrease the number further, however, this kind of slowdown is a bug in the Linux kernel and its totally abnormal.

More errors

I have set the router's ip address range from 192.168.x.x to 10.0.x.x because i wanted to allow the users to join to this network parallel to their own routers. If the ip range doesn't colliding, this should be possible. But its not. Once a computer joins to my private network, his internet stops working on his computer. I have tried everything, i have disabled the DNS server, i have played with all the possible settings, but no use. Linux is retarded enough not to handle the situation when its connected to two separate networks parallelly, and it always tries to access the internet on the WRONG network. After the hard development of the worlds best hobbyists and scripters, this 30 year old bug is still not fixed (probably this would need real skills in programming to be fixed, not just scripting). Not a big loss, but extremely annoying, and i wonder how these retards can get away with it up to this day.

The final steps

The router will obviously placed below the rooftop. I will cut the adapter cable of mine, and i will add an additional 4-5 meter long cable to it, so i can place it everywhere. I will not add a 220w power extension cord just for the router, thats for sure. This will allow me to set up the router relatively easily from random wall plugs, without having to deal with a lot of cables. Luckily the router only eats about 7w under maximal power consumption, so i don't have to worry too much about overheating.

Such WIRELESS very wow

Lessons learned

Long distance Wi-Fi is not as simple as it sounds. Its very expensive to have your own system, regardless of the money you throw on it, it will not work, if the other peers want to connect from an old mobile phone. Every peer has to own a WiFi-hunter kit, or a laptop with super good antenna to be able to connect. Even after spending multiple $100 dollars on this project, soldering wires, cables, and injuring myself, i was not able to extend the range of my WiFi to significant distances, the record i was able to achieve is barely more than the distance of 5 house on the street. Maybe once i mount the antennas to the highest place below the rooftop, i will be able to increase the distance to 6 houses. Of course if i would put the WiFi outside, i would get probably far bigger range in direct air, but unless you want to setup the connection in a blank desert between two camels, the signal will have to travel across walls multiple times, no matter what you do. From a realistic point of view, i don't think its possible to setup long distance Wi-Fi-connections in your neighborhood. Unless of course you live in a large block of flats with multiple floors, and you can direct the signal into everyone's window.

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Avatar for Geri
Written by   86
3 months ago
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Comments

Great idea. I'm leaving a Local area. Wi-fi is so difficult in here. Some days ago i triyed to connected our home but it’s really expensive. So i faild😭

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3 months ago

Came here for the lead image.

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3 months ago