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AZskibum
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Modulation marches forward
AZskibum   12/17/2013 10:40:41 AM
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A 10 dB advantage over 4096 QAM! Just when you think every clever modulation scheme has already been invented, someone comes up with a new breakthrough that shatters old barriers.

I look forward to seeing how this progresses through standardization & productization.

zewde yeraswork
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challenge
zewde yeraswork   12/17/2013 10:52:08 AM
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It seems like a major challenge that companies have to face to have to standardize their communications technology before they cand eploy it and to have to reveal through disclosure much of their advantage to their competitors in the process. It is worth aiming for smaller markets in that case.

 

LarryM99
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Long road
LarryM99   12/17/2013 6:51:03 PM
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This sounds very interesting, but this is a long road with the corpses of a lot of startups alongside of it. Until they go public with details it is going to be hard to see whose ox is going to be gored by this and if it will actually make it out into the world, and if it does, in what form. There are a lot of players in spectrum that have the capability to buy and bury inconvenient technologies or the political wherewithal to block them.

y_sasaki
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Bandwidth Breakthrough
y_sasaki   12/17/2013 7:55:40 PM
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Reminds me that UWB (Ultra Wide Band) fiesta back in 2002-2005, more than 20 modulation schemes are proposed from a number of startup companies with pretty smart people, but sadly, practically none of them survived. The "most popular" UWB scheme was so-called MB-OFDM, similar to WiFi but using faster keying speed (312.5nsec VS 4usec of WiFi), thus wider subcarrier bandwidth. Anyway, even MB-OFDM UWB did not make breakthrough as proposed Wireless USB standard.

Bert22306
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Re: Modulation marches forward
Bert22306   12/17/2013 8:32:42 PM
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It would be interesting indeed. However, we do have Shannon's equation to compare it to, and we do know how close to the Shannon limit other existing techniques come. And we also know that MIMO, under conditions in which multiple propagation paths are very uncorrelated, can give the appearance of violating the Shannon limit, but actually does not.

So, when we get more details, a fair comparison can be made. Anything that is 10 dB better than existing possibilities, aside from MIMO, sounds like it violates the Shannon limit, to me. Aren't we capable of only a couple of dB from Shannon already?

It would be a true breakthrough if it did legitimately violate Shannon's limit, but that wasn't mentioned.

KB3001
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Re: Modulation marches forward
KB3001   12/18/2013 2:42:54 AM
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I agree Bert22306, we need to know more about this 10dB claim because it looks impossible.

zewde yeraswork
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Re: Long road
zewde yeraswork   12/18/2013 9:39:26 AM
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Agreed. There is still a long way to go before this can see the light of day.

dt_hayden
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Issued Patents
dt_hayden   12/18/2013 12:05:55 PM
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A list of 15 issued patents is here.
1 8,605,832 Full-Text Joint sequence estimation of symbol and phase with high tolerance of nonlinearity
2 8,599,914 Full-Text Feed forward equalization for highly-spectrally-efficient communications
3 8,582,637 Full-Text Low-complexity, highly-spectrally-efficient communications
4 8,572,458 Full-Text Forward error correction with parity check encoding for use in low complexity highly-spectrally efficient communications
5 8,571,146 Full-Text Method and system for corrupt symbol handling for providing high reliability sequences
6 8,571,131 Full-Text Dynamic filter adjustment for highly-spectrally-efficient communications
7 8,566,687 Full-Text Method and system for forward error correction decoding with parity check for use in low complexity highly-spectrally efficient communications
8 8,565,363 Full-Text Fine phase estimation for highly spectrally efficient communications
9 8,559,498 Full-Text Decision feedback equalizer utilizing symbol error rate biased adaptation function for highly spectrally efficient communications
10 8,559,496 Full-Text Signal reception using non-linearity-compensated, partial response feedback
11 8,559,494 Full-Text Timing synchronization for reception of highly-spectrally-efficient communications
12 8,553,821 Full-Text Adaptive non-linear model for highly-spectrally-efficient communications
13 8,548,097 Full-Text Coarse phase estimation for highly-spectrally-efficient communications
14 8,548,072 Full-Text Timing pilot generation for highly-spectrally-efficient communications
15 8,526,523 Full-Text Highly-spectrally-efficient receiver

 

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=0&f=S&l=50&TERM1=magnacom&FIELD1=ASNM&co1=AND&TERM2=&FIELD2=&d=PTXT

y_sasaki
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Re: Modulation marches forward
y_sasaki   12/18/2013 12:55:26 PM
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Correct me if I made mistake.

 

Frii's equasion is C=Blog2(1+S/N), while C=data rate (bit/sec), B is bandwidth (Hz), S/N is simple signal-noise ratio (not in dB).

While is is easy to define B, but assuming S/N is trickey part. Typical WiFi usecase is signal level around -70dBm, while background noise floor will be around -90dBm, so SNR is about 20dB.

 

Based on 802.11ac standard, 256QAM MCS9 datarate is 200Mbps per stream with 40MHz channel, short GI, coding rate 5/6. Raw (pre-FEC) rate is 240Mbps.

240=40*log2(1+S/N)

log2(1+S/N)=240/40=6

1+S/N=2^6=64

S/N=64-1=63

S/N(dB)=10*log10(63)=17.99

 

So it proves 802.11ac MCS9 is within typical usecase, even though 2dB margin is pretty low. Of course "typical" usecase could be varied - you'll get -50 - -60dBm signal if your PC is close to AP (within 10ft) so MCS9 will be much more practical.

 

Theoritically, 4096QAM (64x64 constallation) is 16bit/symbol so it should have x2 datarate than 256QAM (16x16 constallaton, 8bit/symbol). Thus, we can assume 802.11ac 4096QAM must have x2 datarate than 256QAM MCS9.

480=40*log2(1+S/N)

log2(1+S/N)=480/40=12

1+S/N=2^12=4096

S/N=4096-1=4095

S/N(dB)=10*log10(4095)=36.12

 

It shows "4096QAM WiFi" will be inpractical (so I don't think WiFi will adopt more-than 256QAM modulation / stream). Even if their claim of +10dB advantage is correct, 26dB SNR will be still tough to find in public wireless networ (WiFi or LTE).

However, it will make sense to backhaul, where dedicated frequency band is used with much higher TX power and highly tuned directional antenna.

rick merritt
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Re: Modulation marches forward
rick merritt   12/18/2013 10:54:26 PM
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@y_sasaki: Nice job runing the numbers.

Does this mean 11ac is about at the limits of what can be done with WiFi and the new modulation scheme won't help? If so, what does that imply for our march to faster, faster, faster?

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