Design Con 2015
Breaking News
Comments
Oldest First | Newest First | Threaded View
<<   <   Page 2 / 3   >   >>
rick merritt
User Rank
Author
Re: Issued Patents
rick merritt   12/18/2013 10:55:19 PM
NO RATINGS
@dt_hayden: Thanks for links to the patents.

I'd love commentary on them from any astute comms EEs out there.

paragdighe
User Rank
Rookie
SNR GAP
paragdighe   12/19/2013 5:00:39 AM
NO RATINGS
The SNR gap to shannon capacity for QAM is ~9.5 dB @ 1e-7 probablity of error.

Lots of literature and links on this. 

http://www.stanford.edu/group/cioffi/ee379a/handouts/pamqam2.pdf

Today's codes achieve very close to this (I have heard). So coding+QAM4096~=capacity. So would be interesting to see which way this company goes especially if you decide to toss the popular OFDM-QAM combination. Who would want them for 1-2 dB improvement ?

 

Parag

paragdighe
User Rank
Rookie
Re: SNR GAP
paragdighe   12/19/2013 5:12:50 AM
NO RATINGS
I guess the catch is that QAM 4096 may be near impossible to implement taking into account the practical implementation issues (EVM etc etc). I think the benefit must be that Magnacom has a scheme theoretically almost equivalent to coded QAM4096. Thats a big deal.

Sheetal.Pandey
User Rank
Manager
Re: SNR GAP
Sheetal.Pandey   12/19/2013 2:17:43 PM
NO RATINGS
well every battle in telecom industry is linked to bandwdth, if there s a breakthrough it will be a new revolutons for the technology.

sridhar.ramesh
User Rank
Rookie
Re: Modulation marches forward
sridhar.ramesh   12/19/2013 4:11:27 PM
4K QAM is 12 bits per symbol without coding - simply log2(4096).

The 10 dB signaling advantage to 2 X power or spectrum advantage to 4X distance advantage referenced in this article don't sit well with each other.

Bert22306
User Rank
CEO
Re: Issued Patents
Bert22306   12/19/2013 4:13:23 PM
All we need is results.

For comparison, the US digital TV standard requires about 15.1 dB of SNR to achieve reception, in a gaussian channel. US DTV uses channel bandwidth of 5.3 MHz (and guard bands that bring this up to the 6 MHz channel width), and a net capacity of 19.29 Mb/s. The Shannon limit for a 5.3 MHz channel carrying 19.3 Mb/s is 10.6 dB of SNR minimum, required.

So this now-20-year-old standard is already only 4.5 dB from the Shannon limit. Unless Shannon's limit can be proved to have been violated, there ain't any 10 dB gains to be had here.

DVB-T2, the new European DTV standard, gets even closer. Last time I checked, it was ~ 3 dB from the Shannon limit.

So, all of this tells me that we're not looking at any "breakthrough in modulation." We're looking at refinements, much like DVB-T2 refined DVB-T1. Marginally better FEC codes, clever tricks on twisting the constellation, better interleaving, and so on. Small improvements that provide a small but measurable improvement.

Also, a significant point here. The purpose of OFDM is NOT to improve spectral efficiency. It is to improve resistance to multipath distortions. There's no such thing as a free lunch. What you pay, with OFDM, is moving away from the Shannon limit. So if a new modulation standard goes back to a single carrier approach, with improved equalizers, no one should be surprised. Equalizers benefit from Moore's law, after all. They are bound to improve over the decades.

y_sasaki
User Rank
CEO
Re: Modulation marches forward
y_sasaki   12/19/2013 4:32:02 PM
NO RATINGS
Thanks. You are right, 4096QAM is 64x64 constallation, 2^6 x 2^6 = 12bit/symbol. I also wrote "Friis equasion" instaed of Shannon... Maybe because I often refer to both equasions to verify "revolutionaly communication method" on news :-)

y_sasaki
User Rank
CEO
Re: Modulation marches forward
y_sasaki   12/19/2013 4:46:49 PM
@ick merritt,

I personally believe 11ac 256QAM is already pushing little bit too far.

As Shannon's equasion (C=Blog2(1+S/N) suggests, the straightforward way to increase datarate (C) is to use more bandwidth (B). This was tried and failed on UWB (initially 500MHz/channel, hoped more than 5GHz/channel for future), partly applied to 11ac (up to 160MHz/channel).

Using higher frequency natunally increase bandwidth/channel, so there is high hope we can achieve more than 1Gbps datarate at 60GHz freq (802.11ad), however its laser-beam like characteristics and extremely low penetoration capability (you only can use 60GHz in clear line-of-sight) will limit is application.

MIMO is another way to increase datarate, but more than 4x4 MIMO will be impractical, since we need set of antenna / receiver / transmitter for each stream.

 

My most honest answer to "how we can get more datarate?" is "use wire!" :-)

BOMBOVA
User Rank
Manager
Re: Modulation marches forward
BOMBOVA   12/21/2013 12:03:15 PM
n Physics, gets streached,    the disbelievers,  speak up.   

elsissi
User Rank
Freelancer
Re: Modulation marches forward
elsissi   12/21/2013 1:02:21 PM

This article and many similar others in the press in the last week, is an example of what you get when you have a marginally good idea and a lot of money to spend on unsubstantiated PR. There is only ONE patent issued in the company name and several applications (not patents). The patent describe a partial signaling transmitted and a maximum likelihood receiver implementation. It is NOT as claimed in the article which strung together all sorts of unsupported superlatives. What a shame!!

<<   <   Page 2 / 3   >   >>


Most Recent Comments
Top Comments of the Week
Flash Poll
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

Tired Old iPad 2 vs. Shiny New iPad Air 2
Max Maxfield
8 comments
I remember when the first iPad came out deep in the mists of time we used to call 2010. Actually, that's only four years ago, but it seems like a lifetime away -- I mean; can you remember ...

<b><a href=Betajet">

The Circle – The Future's Imperfect in the Present Tense
Betajet
5 comments
The Circle, a satirical, dystopian novel published in 2013 by San Francisco-based writer Dave Eggers, is about a large, very powerful technology company that combines aspects of Google, ...

Martin Rowe

Make This Engineering Museum a Reality
Martin Rowe
Post a comment
Vincent Valentine is a man on a mission. He wants to make the first house to ever have a telephone into a telephone museum. Without help, it may not happen.

Rich Quinnell

Making the Grade in Industrial Design
Rich Quinnell
16 comments
As every developer knows, there are the paper specifications for a product design, and then there are the real requirements. The paper specs are dry, bland, and rigidly numeric, making ...

Special Video Section
The LT8640 is a 42V, 5A synchronous step-down regulator ...
The LTC2000 high-speed DAC has low noise and excellent ...
How do you protect the load and ensure output continues to ...
General-purpose DACs have applications in instrumentation, ...
Linear Technology demonstrates its latest measurement ...
10:29
Demos from Maxim Integrated at Electronica 2014 show ...
Bosch CEO Stefan Finkbeiner shows off latest combo and ...
STMicroelectronics demoed this simple gesture control ...
Keysight shows you what signals lurk in real-time at 510MHz ...
TE Connectivity's clear-plastic, full-size model car shows ...
Why culture makes Linear Tech a winner.
Recently formed Architects of Modern Power consortium ...
Specially modified Corvette C7 Stingray responds to ex Indy ...
Avago’s ACPL-K30T is the first solid-state driver qualified ...
NXP launches its line of multi-gate, multifunction, ...
Doug Bailey, VP of marketing at Power Integrations, gives a ...
See how to ease software bring-up with DesignWare IP ...
DesignWare IP Prototyping Kits enable fast software ...
This video explores the LT3086, a new member of our LDO+ ...
In today’s modern electronic systems, the need for power ...