Arpiben Posted August 8, 2019 Share Posted August 8, 2019 5 hours ago, esldude said: I've used it in testing at 2 miles (touch over 3km). There are plenty of people who use them at 5 to 8 miles. In my example the radios automatically lower the transmit power. They would put out more if the distance were greater. Plus I'm shooting thru the branches of a fair sized tree. The speeds I managed at 2 miles were around 100 mbps. And they will drop some with greater range. Ubiquiti has some good charts to figure out how much output, antenna gain, and speed you can expect at different distances. You won't get 200 mbps at 8 miles. You could well get a reliable 25 mbps. The devices I listed above are part of their suggestions for 5-15 km distances. 15 km is a bit over 9 miles. They have other gear for longer distances if needed. They also have a nice bit of software to simulate what you are planning to show coverages and whether you have clean line of site or not. You'll need to get line of sight and pay attention to encroachments on the fresnel zone to get the best out of them at distance. I don't want to over-hype them so people think you can throw a pair of them up and get 8 miles or more. That won't work. You need to apply them properly and mind the details. At a cost of about $100 each, these can be very good for the DIY. Also be warned the Ubquiti forums can be very helpful, but they don't suffer fools or newbies very well. If anyone wanted to contemplate using these this training PDF is an excellent place to start. 71 pages, really about 36 pages with the rest being references and charts. Fairly simple and you could read thru it a little at time. You'll have a good idea of what is possible and how it can be applied. https://dl.ubnt.com/guides/training/courses/UBWA_V2.1_Training_Guide_03-09-17.pdf Correct. For the lowest modulation schemes (4QAM) you may manage much longer. For the highest rates you may reach them with a poor average. I was extremely safe when I wrote 1km.I wanted to changed it to 5 km later but was not offered the choice to edit my post. I don't want people have wrong expectations Nothing against the company or solutions. They are only too much optimistic with the distance vs SNR or received level. Easy to design links with no guaranted availability especially when dealing with no man's land frequency bands. Anyhow it is a good solution. Link to comment
Arpiben Posted August 8, 2019 Share Posted August 8, 2019 5 hours ago, mansr said: No, probably not. Surely not. Capacity depends only on modulation scheme/type and channel bandwidth. Usual channel bandwidth for links up to 60GHz: 7/14/28/40/56/112 MHz (ETSI) 10/20/50/60/...MHz (ANSI) Nowadays modulations are reaching 4096 QAM with such, capacities per single radio are: 112 MHz-> 1Gbps 56 MHz -> 500 Mbps 14 MHz -> 130 Mbps With low modulations such as 4QAM/QPSK 40 MHz -> 60 Mbps 56 MHz -> 80 Mbps 112 MHz -> 170 Mbps Millimeter wave links (mmW) f>60 GHz offer/allow larger channels. Modulation schemes are limited around 256 QAM. Usual C.S. are 62.5/125/250/500/750/1000/1250/1500/2000 MHz. At 128 QAM rates are around: 2 GHz -> 10 Gbps 1.5 GHz -> 8 Gbps .5 GHz -> 2 Gbps 250 MHz -> 1.3 Gbps Link to comment
esldude Posted August 8, 2019 Share Posted August 8, 2019 Finally a little realism about 5G away from urban areas. https://arstechnica.com/information-technology/2019/08/verizon-5g-speeds-on-low-spectrum-bands-will-be-more-like-good-4g/ And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. Link to comment
mansr Posted August 8, 2019 Share Posted August 8, 2019 3 minutes ago, esldude said: Finally a little realism about 5G away from urban areas. https://arstechnica.com/information-technology/2019/08/verizon-5g-speeds-on-low-spectrum-bands-will-be-more-like-good-4g/ Good 4G is still pretty good. Apart from the latency and the drop-outs. Link to comment
botrytis Posted August 9, 2019 Share Posted August 9, 2019 My ISP is a local and offer fiber of speeds 100, 500, 1000 MBs (that is up and down speed). The wife and I went with the middle speed as it was only 10-20 USD more than the 100 speed. There are good things about living in Podunc USA. Current: Daphile on an AMD A10-9500 with 16 GB RAM DAC - TEAC UD-501 DAC Pre-amp - Rotel RC-1590 Amplification - Benchmark AHB2 amplifier Speakers - Revel M126Be with 2 REL 7/ti subwoofers Cables - Tara Labs RSC Reference and Blue Jean Cable Balanced Interconnects Link to comment
Arpiben Posted August 9, 2019 Share Posted August 9, 2019 9 hours ago, esldude said: Finally a little realism about 5G away from urban areas. https://arstechnica.com/information-technology/2019/08/verizon-5g-speeds-on-low-spectrum-bands-will-be-more-like-good-4g/ Do not despair. At least capacity will increase in some rural areas. The point is when.😉 If you want to have a better view of 5G microwave backhauling here is some industry's point of views. https://www.itu.int/en/ITU-R/study-groups/workshops/fsimt2020/Documents/2019.05.02 ITU-R Wireless Backhaul Workshop complete final.pdf Link to comment
esldude Posted August 9, 2019 Share Posted August 9, 2019 50 minutes ago, Arpiben said: Do not despair. At least capacity will increase in some rural areas. The point is when.😉 If you want to have a better view of 5G microwave backhauling here is some industry's point of views. https://www.itu.int/en/ITU-R/study-groups/workshops/fsimt2020/Documents/2019.05.02 ITU-R Wireless Backhaul Workshop complete final.pdf The same spiel was done for 4G LTe, and it too could have made the predicted results. Yet it never happened. Over-promise, under-deliver, and most of all over charge for it all. I can predict with supreme confidence this outline of what will happen is not what will happen. Advances have been made, but not according to plan (other than becoming stupidly rich if you have the right influence and positioning). 5G is over-hyped way beyond the pale. It will happen, it will make a difference, and those in the outlying areas will not be adequately catered to. Low level satellite has the potential to break up this little play house of greed and economic rape of the populace. I hope it utterly crushes those trying to profit and remain the gate keepers into utter oblivion. And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. Link to comment
Popular Post mansr Posted August 9, 2019 Popular Post Share Posted August 9, 2019 26 minutes ago, esldude said: Over-promise, under-deliver, and most of all over charge for it all. That's how it works in the land of the free, and it won't change as long as Pai is at the FCC. Ralf11 and botrytis 1 1 Link to comment
Arpiben Posted August 9, 2019 Share Posted August 9, 2019 1 hour ago, mansr said: That's how it works in the land of the free, and it won't change as long as Pai is at the FCC. 👍 Bandwidths are allocated by international regulatory bodies such as the European Telecommunications Standards Institute (ETSI) and the Federal Communications Commission (FCC) in the United States. Bandwidths rights to use (frequency allocation) are paid to ETSI/FCC/etc... Bandwidths fees per bandwidth/year are paid to ETSI/FCC/.... When equipment providers implement new technology for better spectral efficiency, government bodies are fast to implement new fees based on bits/bandwidth and not anymore bandwidth size.😊 I don't think it is a matter of the person ruling the regulatory body. Link to comment
Arpiben Posted August 9, 2019 Share Posted August 9, 2019 For those who might be interested. Data rate vs bandwidth applied to wireless transmission: In 1928, Harry Nyquist published a paper called Certain Topics in Telegraph Transmission Theory. In the paper he showed that in a noise-free channel, we can transmit data at a rate of up to: Cmax=2*B*log2(M) bits/s where B is the bandwidth (in Hz) and M is the number of signal levels. Calculating symbol rate For an M-QAM system, log2(M) bits per symbol can be transported If B=28 MHz channel spacing, it is possible to transmit up to B=28 10e6 symbols per second in an ideal world. In practice, there is always a slight degradation compared to the ideal number, so that: B = Symbol x (1+alpha) Alpha is often referred as roll-off. It takes into account all of the implementation-related impairments that reduce throughput. Today, typical roll-off values are in the range of 0.10 to 0.15. This means that with 28 MHz channel spacing and an alpha value of 0.12, it is possible to transmit around 25 MHz symbols Calculating bit rate • With 4-QAM, 2 bits per symbol are transmitted.-> M=2 • With 256-QAM, 8 bits per symbol are transmitted.-> M=8 • With 4096-QAM 12 bits per symbol are transmitted -> M=12 With 4096-QAM, that results in 25 x 12 = 300 Mbps throughput. Dealing with Wireless Transmission question is how much of the throughput over the air is user information and how much is overhead? Answering this question requires looking at the theory of error correction codes. Shannon: improving error correction The Shannon theorem states the maximum data rate under a noise condition: Cmax=B * log2 (1+S/N) bits/s where B is the bandwidth (in Hz), S is the signal power and N is the noise power In 1948, Claude Shannon published a theorem to describe the maximum possible efficiency of error correcting methods compared to levels of noise interference and data corruption. Known as Shannon’s law, the theorem forms the foundation for the modern field of information theory. It states, that given a noisy channel with channel capacity C and information transmitted at rate R, codes must exist that allow the probability of errors at the receiver to be made arbitrarily small. This means that, theoretically, it is possible to transmit information almost error-free at any rate below a limiting rate, C. Researchers have made many attempts to identify the best way to achieve — or at least get close to — Shannon’s limit; that is, to reach Shannon’s capacity with an arbitrary low-error probability. Reed-Solomon codes, MLC codes and Viterbi codes are examples of error correction codes that have been widely adopted. In 1993, a major step toward achieving Shannon’s limit was reached when Claude Berrou and Alain Glavieux introduced turbo-codes in their paper Near Shannon Limit Error-correcting Coding and Decoding:Turbo-codes. A further, and most probably ultimate, step was achieved with the low-density parity-check (LDPC) code. LDPC is the most recent code introduced by the error correction code community, and it performs very close to Shannon’s limit. LDPC: Error correction at its best The LDPC code was first conceived in 1960 by Robert Gallager in his Massachusetts Institute of Technology (MIT) thesis, however, implementing it was not practical at the time. In 1996, David MacKay of Cambridge University and Radford Neal of the University of Toronto developed the first practical LDPC implementation. Today, LDPC remains the most efficient error correction code available. To reach Shannon’s limit, an error correction code must be used. However, by definition, an error correction code always introduces overhead that protects the user information from noise. The higher the overhead, the higher the protection from noise, but the lower the throughput. The microwave industry has adopted codes with overhead in the range of 5% to 15%. While codes such as LDPC are more efficient than others, the impact on overall throughput must always be considered. With error correction, the previous 300 Mbps at 4096 QAM becomes 300×0.9=270 Mbps in terms of net capacity — the bits sent by users before they are affected by the code. esldude 1 Link to comment
esldude Posted August 9, 2019 Share Posted August 9, 2019 9 hours ago, mansr said: That's how it works in the land of the free, and it won't change as long as Pai is at the FCC. As much as I despise Pai, it wasn't really any different before he was there. Pai has a complete lack of shame for being a shill for the industry when he supposed to be a regulator. But the results aren't new or different. And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. Link to comment
mansr Posted August 9, 2019 Share Posted August 9, 2019 4 minutes ago, esldude said: As much as I despise Pai, it wasn't really any different before he was there. Pai has a complete lack of shame for being a shill for the industry when he supposed to be a regulator. But the results aren't new or different. Sure, replacing Pai is no guarantee for change, but it is a prerequisite. Link to comment
botrytis Posted August 9, 2019 Share Posted August 9, 2019 35 minutes ago, Ralf11 said: we need to Agitate Pai Just get rid of his ass. I mean he will probably go back to where he came from Verizon....... Current: Daphile on an AMD A10-9500 with 16 GB RAM DAC - TEAC UD-501 DAC Pre-amp - Rotel RC-1590 Amplification - Benchmark AHB2 amplifier Speakers - Revel M126Be with 2 REL 7/ti subwoofers Cables - Tara Labs RSC Reference and Blue Jean Cable Balanced Interconnects Link to comment
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