Remote internet via SDR - Page 1
Forum section: electronics / rf-microwave

author: Free_WiFi
author_rank: Regular Contributor
timestamp: April 21, 2019, 07:56:42 pm
content: Why there's no protocols wich could allow us to use the SDR tecnology for remote internet connection?I didn't know how to explain what i really mean(because of my low english skills)however my idea and question at the same time is:why the sdr radio can't be used like an reapetitor for remote internet connection?

author: Free_WiFi
author_rank: Regular Contributor
timestamp: April 21, 2019, 08:02:27 pm
content: For example:with this kind of tecnology(+ an directional dish antenna),we could be able to share our internet with people from far away like 200km's.This is 1 kind of example.

author: ElectronicCat
author_rank: Regular Contributor
timestamp: April 21, 2019, 08:17:36 pm
content: I'm not exactly sure what you mean. With a sufficiently powerful SDR and a lot of DSP you could get 802.11ac WiFi working on an SDR if you wished.What I suspect you mean is why are there no protocols which can be easily implemented in low cost SDRs. And the answer is that I suppose is that it would serve little purpose standardising for something which isn't best suited for the application. WiFi and other RF transceivers are cheap and commonly used for the type of range extension and last-mile connectivity you're describing. You could always come up with your own PHY and MAC layers to be implemented on an SDR if you wished, and then transmit data to and from the internet by implementing IP and above layers, however the data rates will likely be abysmal and the cost of your SDR solution will be more than a commercial microwave transceiver for probably lower power and sensitivity.

author: Free_WiFi
author_rank: Regular Contributor
timestamp: April 21, 2019, 08:21:05 pm
content: Quote from: ElectronicCat on April 21, 2019, 08:17:36 pmOoh seems like the sdr tecnology is not that limitless as I thought before..

author: ElectronicCat
author_rank: Regular Contributor
timestamp: April 21, 2019, 08:25:57 pm
content: Quote from: Free_WiFi on April 21, 2019, 08:21:05 pmSDR is great for research, working with unknown protocols and such but for high volume fixed installations you can't beat dedicated hardware for the task.

author: OwO
author_rank: Super Contributor
timestamp: April 22, 2019, 03:23:46 am
content: Don't overestimate the efficiency of wi-fi. If you look at sensitivity specs of any off-the-shelf wi-fi hardware it is over 20-30dB from channel capacity limits, and far worse at the lower bit rates. Even the AX5043 can get within 13dB of the Shannon limit. 7dB of that is due to the weak FEC, 3dB due to noise figure, and remaining 3dB is due to the use of FSK. How wi-fi hardware manages to fuck it up even with a strong FEC and QPSK/BPSK is beyond me, but it doesn't surprise me because wi-fi hardware are designed for indoor use where performance is interference limited and not noise figure limited. I don't think it's hard to beat wi-fi at all for long range data links, if you implement your modem properly and don't skimp on RF design in your SDR (e.g. SAW filters, LNA, high linearity signal path, etc).

author: OwO
author_rank: Super Contributor
timestamp: April 22, 2019, 03:34:26 am
content: The other thing to consider is that the 802.11 protocol is absolute shite for anything other than indoor smartphone/laptop use. The high protocol overhead means it's unusable at the lower bitrates, the listen-before-talk means you are unable to transmit anything as soon as you have unexpected environment noise, and the packet radio modem means you waste significant time transmitting preambles, while a long preamble IS necessary to get reliable lock at low SNR.The solution of course is a continuous streaming OFDM transmission, not unlike LTE, where the base station transmitter is always on so that the other end can maintain lock. Do away with listen-before-talk and have the other end explicitly communicate channel quality of each OFDM subcarrier, then you can shut down subcarriers that get significant interference. Finally the stations must be full duplex (separate bands for transmissions going each direction) beause you have to maintain continuous transmission on both ends. And of course, do away with all the handshaking/association parts of 802.11 because you want a permanent link.

author: extide
author_rank: Regular Contributor
timestamp: April 22, 2019, 03:35:33 am
content: To get decent speed you will want an SDR with a wide bandwidth. The Lime Mini and Lime SDR are the best ones that are reasonably affordable that I am aware of, the Lime Mini is about $159 and has 30.72Mhz of RF b/w, while it's bigger brother the Lime SDR can do 61.44Mhz for $299. I really want to get one of them to play with at some point. I mean, to actually make a link work reliably this is going to be pretty complex and if you actually want something usable across 200km I would suggest looking at the Ubiquity Air Fiber or Air Max products as that is probably the cheapest/fastest off the shelf stuff you can get.

author: 0culus
author_rank: Super Contributor
timestamp: April 22, 2019, 03:39:08 am
content: I just saw something the other day about a guy who needed a 2 mile link to a rural house, so he rigged up a wifi router with a high gain Yagi and claimed he was getting 7 Mbps down...

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 02:05:33 pm
content: QuoteUse 2 CB Radio with Packed Radio Links.And pls dont argue about the speed.

author: wraper
author_rank: Unknown
timestamp: April 22, 2019, 02:18:59 pm
content: Quote from: 0culus on April 22, 2019, 03:39:08 amActually it's not a so good result. You could do better, especially in rural area. All you need is unobstructed path between highly directional antennas.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 02:28:17 pm
content: Here in Austria are certain Freq for Directional Radio communication.There was a Page how does the Austrian Military use a Network of Dish and Reflector for that.

author: radiolistener
author_rank: Super Contributor
timestamp: April 22, 2019, 02:30:24 pm
content: The best way to get remote internet is optical fiber.It gives you incredible speed and no need to fight with interference and noise issues.Optical fiber is much-much faster than any radio-link and even any wired network.Also you can build your own DIY gigabit data-link with infrared lasers:https://hackaday.com/2016/03/10/gigabit-ethernet-through-the-air/

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 02:37:08 pm
content: QuoteSure if everything is on your own property. If not you are screwed up. If it run over Public Ground good look to get a Permission.Quoteuntil a Bird cross. Laser are not that legal in many ways. The dont have to interferer with Aviation (that include Heli). In my Area from Time to Time a Rescue Heli land so the could not get blindet by that.

author: radiolistener
author_rank: Super Contributor
timestamp: April 22, 2019, 02:43:29 pm
content: Quote from: Lord of nothing on April 22, 2019, 02:37:08 pmif you want to use radio-link (SDR based or any other kind of technology), you will need to get Permission even for communication on your private groundAnd I'm afraid it will cost you much more and license will be much more complicated, than a small optical fiber through public ground.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 02:45:47 pm
content: Depend when I stay with the 1W on 5Ghz Wifi I can do what every I want.If you use other Band or what ever you need a Permission and here in Austria the arent that cheap.

author: radiolistener
author_rank: Super Contributor
timestamp: April 22, 2019, 02:48:25 pm
content: Quote from: Lord of nothing on April 22, 2019, 02:45:47 pmthis is because this band is already licensed for WiFi and you're granted permission to use certified WiFi equipment for such bands. But you cannot use it for other purposes than WiFiI'm sure that low power IR laser communication will be much more easy and give you much less headache.

author: Bicurico
author_rank: Super Contributor
timestamp: April 22, 2019, 02:50:28 pm
content: SDR is just a software replication of radio hardware.Why would you want to use SDR for wireless internet if there is already WIFI/WLAN with hardware implementation?Also, amateur radio communication may NOT be used for encrypted and/or commercial communication! This rules out relaying internet access to any amateur radio frequency.

author: radiolistener
author_rank: Super Contributor
timestamp: April 22, 2019, 02:53:57 pm
content: Quote from: Bicurico on April 22, 2019, 02:50:28 pmAnd I think almost any WiFi/WLAN already uses SDR technology internallyBecause SDR technology come to amateur radio from commercial communications, such as GSM/CDMA and other kind of digital radio-link communications, where SDR is already used for a long time.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 03:02:35 pm
content: https://www.ui.com/airfiber/airfiber5/QuoteSure but the must be very directional. Do you ever use that in a practise?QuoteWhen I transmitt just Numbers are the Encerypt or not? (aka Number Station).Thats why I still recommend still CB Radio here in Europe.https://en.wikipedia.org/wiki/Packet_radioMilitary Techniqe was one of the first user of SDR Stuff.When my Fiber Connection @Home work I will turn the CB Radio back on and Transmitt 24/7 stuff.

author: wraper
author_rank: Unknown
timestamp: April 22, 2019, 03:21:57 pm
content: Quote from: radiolistener on April 22, 2019, 02:30:24 pmI would like to see how you would install a few km of optical fiber, especially not in your property.QuoteTry that outdoors over a few km. Even if ignoring rain, fog and birds, long term positioning would be a big trouble on it's own.

author: extide
author_rank: Regular Contributor
timestamp: April 22, 2019, 03:41:59 pm
content: Quote from: radiolistener on April 22, 2019, 02:48:25 pmNo it's an ISM band which means you can use it for just about anything as long as you stay within the power limits.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 04:39:28 pm
content: Nope a Transmitter who work on a ISM Band must be from the Manufacture declared to be in the Specification. The same for CB Radio and PMR446 Radios.

author: radiolistener
author_rank: Super Contributor
timestamp: April 22, 2019, 05:07:21 pm
content: Quote from: wraper on April 22, 2019, 03:21:57 pmI would like to see how you would install a few km radio-link for high speed data transfer with custom protocol and with no license and no payment for the frequency band...Quote from: wraper on April 22, 2019, 03:21:57 pmthe same issue with radio link. For example, when you use WiFi, other WiFi routers make iterference and leads to connection break.

author: wraper
author_rank: Unknown
timestamp: April 22, 2019, 05:19:58 pm
content: Quote from: radiolistener on April 22, 2019, 05:07:21 pmYou don't need anything custom. Just wifi with good directional antennas. And if you need it faster and more reliable, there are solutions made specially for that, although way more expensivehttps://www.saftehnika.com/en/integrae.QuoteNot the same at all. The main problem (alignment) I mentioned already makes it a no-go. Others are just an addition. With directional antennas, interference is not such a big deal for wifi, especially in rural areas. Again, get a special solution as said above.https://www.saftehnika.com/files/downloads/367eec22-af4c-e911-8f79-0050569a8c0f/Integra-E%20distance%20graphics%202019%20in%20MILES.pdf

author: wraper
author_rank: Unknown
timestamp: April 22, 2019, 05:27:39 pm
content: Here is some cheaper 1 Gbps model:https://www.saftehnika.com/en/integrawsQuoteSome pricinghttps://www.streakwave.com/product-saf-tehnika.asp

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 22, 2019, 07:27:50 pm
content: Affordable ready made 900MHz point to point network hardware:https://www.balticnetworks.com/ubiquiti-nanobridge-m9-900mhz-13dbi-dual-polarity-dish-bridge-solution.html

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 07:51:30 pm
content: Sure we an afford a GSM Licence.

author: ogden
author_rank: Super Contributor
timestamp: April 22, 2019, 08:17:00 pm
content: I wonder why nobody though of building wireless internet connections using vector signal generators paired with vector signal analyzers?

author: wraper
author_rank: Unknown
timestamp: April 22, 2019, 08:18:44 pm
content: Quote from: Lord of nothing on April 22, 2019, 07:51:30 pmThere are different versions of it, say 2,4 GHz, if you cannot use 900 MHz.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 08:24:49 pm
content: Quote from: NiHaoMike on April 22, 2019, 07:27:50 pmi mean that post here.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 22, 2019, 11:04:50 pm
content: Quote from: Lord of nothing on April 22, 2019, 07:51:30 pmThat's their version of LTE-U, the U for unlicensed.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 22, 2019, 11:20:55 pm
content: What did you mean? For LTE you have to buy a Licence for a Time Period.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 23, 2019, 02:10:33 pm
content: https://en.wikipedia.org/wiki/LTE_in_unlicensed_spectrumNote that the Ubiquiti unit does not implement actual LTE-U but rather a proprietary version of it that works in a similar manner. Would be interesting to see a teardown but I suspect it's just a LTE radio with some custom programming.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 23, 2019, 02:40:42 pm
content: https://www.ris.bka.gv.at/Dokumente/Bundesnormen/NOR40188658/II_390_2016_Anlage_2.pdfShow me where it is! Sub-Class H01?Quote

author: extide
author_rank: Regular Contributor
timestamp: April 23, 2019, 05:51:31 pm
content: Quote from: Lord of nothing on April 22, 2019, 04:39:28 pmWhat do you mean by "from the Manufacture declared to be in the Specification" ?I am not particularly familiar with how the laws which regulate ISM bands work outside of the US but I do believe they are similar to the US. You can use the ISM bands for anything you want as long as you stay within certain power/eirp limits. See FCC Part 15, sections 107, 109, 205, 207, 209, 247, 249. Stuff like microwave ovens, inductive heaters, and even RF exciters for gas lamps use these frequencies as well. These bands are not licensed for Wifi, they are specifically unlicensed.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 23, 2019, 06:28:55 pm
content: Here in Europe the Manufacture must declare that the Product is Law confirm.For example:https://www.alan-electronics.de/alan/CustomUpload/374O357O340O370O356O369O350O320O363O352O365O/AE6110_CE_Declaration.pdfIf your Product dont have anything lile that you are not Permit to turn on.

author: extide
author_rank: Regular Contributor
timestamp: April 23, 2019, 06:31:10 pm
content: Quote from: Lord of nothing on April 23, 2019, 06:28:55 pmAh ok, then I would assume you could say it complies with the EU version of those same/similar FCC rules.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 23, 2019, 06:41:52 pm
content: The Company must declare it conformity. You cant build your own stuff (beside of pro certificate Stuff) and use it without an external Certification.

author: extide
author_rank: Regular Contributor
timestamp: April 23, 2019, 07:10:56 pm
content: Quote from: Lord of nothing on April 23, 2019, 06:41:52 pmSo could you perhaps build something using an off the shelf RF module of some sort as long as that module is certified?

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 23, 2019, 07:29:01 pm
content: You want built your own 868Mhz Thermometer you can use a Module who is certified and you get a written conformity declaration.Sure you cant modify anything like a Antenna with more gain.