At the height of power and splendour is small fat
One is had the honor to read on the net yesterday from media article " why Gaotonghua is fond of for the predestined relationship pack 4.9G 5G and do one's best is popularized " , 5G of article lieutenant general upgrades to the technology of 4G assimilate to widens driveway, is not to let original car run on the road faster car, more cars, although the academic career of 5G promotes,arrived accordingly 10 times of 4G system, communication technology also is done not have how old progress, 5G just is the 4.9G after packing, be China the method that waits for big company kite to be connected high. This article author is expecting the major breakthrough of communication technology. The author serves as from course of study newsletter industry of near 20 years is veteran, if fishbone,be in to these views in the article larynx. If speed promotes 10 times still do not make significant progress, does then this author expect the progress of what communication technology? Should break through sweet farming does the limit just make progress?
Above all, want to introduce a common sense. The author of modern information theory is sweet farming (Claude Elwood Shannon) put forward 1949 famous sweet farming formulary, in proving the channel that is being disturbed by gauss white noise strictly, c of deferent rate of the biggest news decides by undermentioned formula:
C=H*log? (1+S/N)
Among them the limiting value that C is news rate, h is channel bandwidth, unit Hz; S is signal power (made of baked clay) , n is noise power (made of baked clay) . Any communication have noise in channel, the user is more noise is stronger, n impossible random is so small; Signal power cannot rise indefinitely, the impact that considers pair of human body health in fact and the interference that nod to frequency of professional news report, each country government is right base the emissive power of station and mobile phone has restriction, so the upper limit of S was decided by the lock; So promotion C increases H only.
Sweet farming information theory set the news speed limit in onefold channel, just like velocity of light cannot be surmounted commonly, also become so sweet farming the limit. So was 4G LTE system achieved sweet farming how many ultimate?
According to theoretical analysis, the outcome that computer simulation and effective way measure, 4G LTE network is in SISO (sheet goes out into sheet, base station and mobile phone use an antenna only) below the condition, communication rate has been achieved sweet farming ultimate agreement 90% the left and right sides. Because level of the noise in the system of research of each research organization place has difference, so the number comes in and go out somewhat. But achieve sweet farming of the limit 9 becoming the left and right sides is the fact that everybody can see. In fact the WIFI system of our family expenses is in newest standard, also be this number almost.
Yes, human communication technology has reached the limit 90% . This is meant as long as sweet farming information theory was not overthrown, no matter prospective mankind invents what kind of modulation way, how advanced encode means, relative to the efficiency promotion that piles up at the 256QAM modulation in 4G system and Turbo, can have the percent of a digit only. is the mankind OK at this point go no further not before? Of course won't.
Much antenna technology is one of methods that the mankind thinks up. The MIMO technology in 4G standard, the photograph in 5G standard accuses a beam figuration technology, it is the application of much antenna. Those who need ambitious shift is, MIMO and beam figuration technology were not broken sweet farming the limit. Sweet farming what the limit answers is onefold channel, MIMO and beam figuration are to used much antenna to make many channel on same frequency dot actually, be to accord with in every channel sweet farming of the limit. Already the scholar is opposite sweet farming formula undertook transforming below MIMO condition, here introduces no longer.
Another technology is developed namely more high frequency paragraph. Here also says more no longer.
However real environment should want than perfect environment complex much. Radio is not simple attenuation in the transmission in air, the signal that receives debit to receive should get multipath transmission (launch square signal to be reflexed by different object, through different method, be arrived at in different time by different attenuation receive debit) , disturb (white noise, industrial interference, more interference waits other user a moment greatly more) , transmission defer waits the influence of the element a moment. When rate amounts to high fixed rate, it is very difficult to rise again. These a few years, the OFDM that the mankind invents, CDMA, all sorts of error correcting code, all sorts of processing technologies, can raise communication rate in onefold channel at long last sweet farming of the limit 9 into. Although 5G is used the percent that all sorts of technologies carry tall digit only than the efficiency of 4G, but if do not have these technologies, efficiency can drop more.
Anyhow, the effort that the author of that article debases newsletter industry does not have a truth. Repairing wide driveway also is the method that solves a problem. The major breakthrough of the communication technology that he expects, be afraid can be a breakthrough only sweet farming information theory.
Sweet farming the derivation that information theory formula is pure maths, the process is perfect, do not have the common hypothesis constant in physics formula among them. This formula has the requirement that sets beforehand to channel noise really, but will treat these conditions at present is reasonable. There is some of scholar to be in really on the world the theory with new research, try to break through sweet farming information theory, for instance FTN (Faster Than Nyquist exceeds Nai Kui this special) namely among them a direction. But current and all theory is far still from the breakthrough, from practical and farther. When can break through after all, everybody says bad, perhaps 10 years, perhaps 100 years.
So progress of human science and technology won't stop offal pace, 5G system is in approach sweet farming 4G system was provided below ultimate circumstance the rate of 10 times, it is the result that industry of whole news report tries hard, it is tremendous technical progress. If stop not before, wait on 10 years or 100 years, reopen delivers next generation systems, that ability is human distress.
