Those who cannot learn from history are doomed to repeat it

Perhaps the most famous example of telecommunication fiction is the broadband telecom bubble of the 1990’s. An interesting book on this subject is Broadbandits: Inside the $750 Billion Telecom Heist. One can find a huge amount of information on this topic on the web. This story has to do mostly with non-wireless communications (except for the fixed wireless broadband fiasco), but  there are  useful lessons to be learned from it about the potential dangers of “wireless fiction”. When the gap between the claims made about technologies and reality becomes too large, bad things happen.

The telecom bubble is only one of many well known economic bubbles fueled by the tremendous power of fear and greed. One of the classical books on this topic is “Extraordinary Popular Delusions and the Madness of Crowds” by Charles Mackay. You can download the book from here or here. The first chapter “The Mississippi Scheme” opens with the quote:

“Some in clandestine companies combine;
Erect new stocks to trade beyond the line;
With air and empty names beguile the town,
And raise new credits first, then cry ’em down;
Divide the empty nothing into shares,
And set the crowd together by the ears. –Defoe.”

The book, which was first published in 1841, does not deal of course with modern technology delusions. However, each time I read the book I am struck by the similarity between the events it describes and events unfolding today. As Yogi Berra used to say “it’s deja vu all over again”.

Hmmmm … part II

In the earlier post titled “Hmmmm …” I mentioned a Mr. Marc Dannenberg who seems to be systematically scouring the web for any critical comments about xMax and posting abusive responses in an apparent attempt to discourage criticism by intimidation. He sent me numerous e-mails consisting primarily of virulent profanity and has also left me telephone messages in a similar vein. He has done a few other things which I prefer not to discuss in a public forum.

A reader of this blog sent me today a link to a filing of Far Reach Technologies which states that the aforementioned Mr. Dannenberg is an officer of this company. This is getting curiouser and curiouser. Far Reach as you may recall is the company who is supposed to roll out the xMax network this month. We have an officer of this company actively working to squash valid technical criticism of this technology. Just to give you an idea of the quality and logic of his technical arguments here is one of the milder e-mails he sent me.

Sent: Tuesday, July 10, 2007 12:27 PM
Subject: You are a dumb motherfucker

I have a question, you stupid motherfucker, how did you get so stupid…were you dropped repeatedly on your head? Who the fuck is responsible for giving an imbecile like you a job educating others? He should be strung up by his balls. I can´t wait until you are fired.”

If any of the kind readers have something they want to say about this type of behavior and what this may imply about the  xMax story, please do not hesitate to post your comments.  I am going to refrain from speculation, tempting as it is.

Off we go, into the wild blue yonder

A kind reader sent me the following link to Far Reach Technologies – a small ISP in Florida with gradiose plans. We read on their web page that: “Far Reach is poised to take the next step and become the very first xMAX mobile VoIP network carrier in the world in what will be the largest wireless network service rollout in history.”

Forget all the technical issues we have been discussing in this blog (and many other issues which remain to be addressed), or the fact that xMax has apparently not been tested even in a single multi-user cell in a typical urban deployment. They are ready to take on the world! Well, at least the US: Far Reach Technologies today (10/16/2006) announced that it will be launching mobile VoIP and Broadband services in 76 markets across 8 states in the US“.

And how will this be done I hear you ask? By the magical properties of xMax of course. We read once again that “The key value proposition for xMax is that it lowers the cost of deploying broadband services. xMax accomplishes this by increasing the range of RF signals. By delivering broadband signals orders of magnitude farther than other technologies operating at the same frequency and power level, xMax reduces the amount of infrastructure required to cover a given area wirelessly by 25-50 fold depending upon the terrain.” The fact that these claims are certifiably false does not dampen the enthusiasm of this company in the least.
But my favorite part is the simple but poignant statement: “The disruptive technology created by xG is the greatest technical advance in RF communications in 100 years.” Now you know …

Well, at least no one will accuse them of false modesty.

So who can you trust?

I know next to nothing about Frost & Sullivan, but based on the information on their web page they are “the world leader in growth consulting and the integrated areas of technology research, market research, economic research, corporate best practices, training, customer research, competitive intelligence and corporate strategy.” They seem to be a very respectable market analysis company. If one reads material produced by a Frost & Sullivan analyst, one expects that it would be credible and trustworthy. So what is one to make of reading a recent article which includes the following quote attributed to an F&S analyst:

“The company’s sustainable competitive advantage lies in this proprietary modulation method, which differs from rival technologies that use tens to hundreds of thousands of waves to convey the same bit of information,” explains Thomas. “As each additional cycle requires commensurate power output, xG’s Flash Signal technology allows dramatic efficiency gains to be achieved and results in increased RF signal range.”

and also

“… adds Thomas. “Moreover, in the context of power efficiency resulting from single-cycle signals, tests have shown that an xG base station transmitting full-motion video uses 3 million times less power than a typical 802.11 access point.””

How can anyone with some knowledge of wireless communications say this with a straight face?

The Thomas quoted here is (based on his web page) “Luke Thomas – a Research Analyst with Frost & Sullivan’s ICT Europe practice, specializing in wireless content and applications, and wireless broadband technologies.” In an earlier post “Theater of the Absurd” I have addressed a presentation by the same analyst where xMax is described as a likely competitor to WiMax and 3G LTE (I am not making this up!).

I am also completely baffled by the “Technology Innovation Awards” given by Frost and Sullivan to Gaiacomm International in 2004 (see my post “Wild Wireless”), and to xG Technology in 2007. What kind of a technical review was conducted before deciding to give these awards? I can’t imagine how any competent communication engineer could have approved these awards. I encourage the reader to look up Gaiacomm to fully appreciate the “reality failure” involved here.

So how can we trust anything we read on the web about wireless communication technology, even if it comes from seemingly respectable sources? If anyone has an answer to this rhetorical question please let me know ….

BER vs. Eb/N0 plot – round III

So today a new “disclaimer” appeared on the xG Technology web page above the BER vs. Eb/N0 plot saying:

“Range and penetration are functions of both Eb/No and system characteristics. This chart depicts the Bit Error Rate (BER) of xMax vs. other typical modulation systems based solely on equal Eb/No, but does not depict the performance provided by xMax system gain which can add substantial advantage.”

Two communication systems differing by the modulation technique, such as xMax and a system using conventional modulation, but otherwise having the same parameters (data rate, transmit power, transmit/receive antenna gains, operating frequency, bandwidth, noise figure, etc.), will have the same range and penetration. In other words, in a fair one-to-one comparison of two communication systems, knowing that they require the same Eb/N0 to operate at a specified BER, immediately tells you that they will have the same range and penetration.

Having published a BER vs. Eb/N0 curve showing that xMax performance is very close to that of conventional communication systems, it makes no sense from a technical standpoint to argue that xMax has better range and penetration (again, assuming a fair comparison). As I tried to explain in an earlier post “Understanding the range of wireless systems”, the key issue is the maximum pathloss which the communication system can overcome. This pathloss can be calculated doing a link budget. The effect of the modulation technique enters the link budget only through the required Eb/N0.

To put this in simple and completely non technical terms: you can’t have your cake and eat it too ….

The xMax story to date

Given the various questions that keep coming from readers I want to briefly summarize where we are on the xMax issue from a technical standpoint.

xMax is a new modulation technique using a particular type of waveform. It’s performance is comparable to that of conventional techniques. As a physical layer it does not offer any advantage over the physical layers used in existing systems. Statements made on the xG ompany webpage such as “… xG Flash Signal will offer significant improvements in speed, range, and power savings over existing technologies.” and “xG Flash Signal is a breakthrough system design that improves RF signal performance at its most elemental level – the physical layer. Flash Signal uses revolutionary single cycle modulation to deliver longer range and lower power communications.” are not supported by any data and are in direct contradiction of well established principles of communication theory, as well as xG Technology’s own BER curve. All of the claimed advantages of xMax derive from the one basic claim of power efficiency which is simply false. Given xG Technology’s publication of the BER vs. Eb/N0 curve I hope that we can put to rest these claims and move on to other more interesting topics.

The fact that xMax offers no advantages as a physical layer does not mean that it can not work. Technical analysis of xMax shows that in principle it can be used as the physical layer of a wireless network, provided that xG Technology addresses the myriad of other issues involved in building such a network. It should be clearly understood, however, that the xMax based network can not perform better than a network built using conventional communication technology. While I find it puzzling that someone will go to so much trouble to re-invent the wheel, when perfectly good (or better) wheels are readily available, this is a business decision which is beyond the scope of what I want to discuss in this blog.  There may well be valid non-technical reasons for this approach.

As far as I am concerned we seem to have exhausted the issue of the xMax modulation technique – there is simply nothing very interesting there. Now a complete working system involves many issues beyond the choice of the modulation technique which has been the focus of the discussion so far. There are physical layer issues such as the multi-access method (FDMA, TDMA, etc.), handling of fading, rate adaptation, choice of coding, power control, use of multiple antennas, and so on. Then there is the MAC layer and its various protocols, scheduling of users, Quality of Service, mobility, handoff, and the list goes on. Very little information seems to be available at this time on how these topics are being addressed in the overall xMax system. The information provided by xG Technology, its patents and the media, focuses almost entirely on the modulation technique and its non-existent advantages. This is rather peculiar and potentially worrisome. I hope to discuss some of these issues if and when some meaningful technical information about them becomes available.

BER vs. Eb/N0 plot – round II

[Note added on 28 July, 2007:   The disclaimer discussed in this post seems to have been removed today from the xG Technology web page]

Well, I spoke too soon. I thought that xG Technology has finally decided to come to grips with the fact that xMax has no technical advantages as a physical layer, and move on from there. I was wrong. They have now added the following “disclaimer” to the BER vs. Eb/N0 plot:

“In response to numerous requests, following is a plot showing BER (bit-error-rate) performance against Eb/No (signal-noise ratio). It should be noted that, due to the unconventional nature of xMax technology, traditional BER plots such as these do not convey the true inherent advantages of xMax over existing technologies. These advantages will become evident in the first commercial xMax systems.”

So xMax has some unspecified “true inherent advantages over existing technologies.” These must be different from the advantages mentioned before, which relied on the claim that xMax can operate at vastly lower power levels than existing techniques, a claim clearly falsified by the BER vs. Eb/No plot (as well as by all the other issues discussed in earlier posts). Sounds rather mysterious and intriguing – we will have to wait and see what new advantages arise from the ashes of the old.