Updated: 5/16/2006; 11:34:14 AM.

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daily link  Sunday, February 29, 2004

The End of Spectrum Scarcity:  Excellent summary of current wireless developments and basic industry impacts.  "New radio transmission and networking technologies can squeeze more and more capacity out of the same spectrum. Some of the improvement comes from the shift from analog to digital transmission. ..

Even greater improvements in spectrum usage will come from a family of technologies that use the computational intelligence of today's wireless devices to allow multiple systems to "share" the same spectrum. The first of these, spread spectrum, replaces ancient high-power, undifferentiated narrowband transmissions with modern low-power, coded wideband signals  ..  A newly permitted method of using spectrum, ultrawideband, takes spread spectrum to its logical conclusion, operating at such low power that, subject to appropriate safeguards, it can underlie existing licensed services. That is, preexisting users of the same spectrum bands won't even know the ultrawideband transmissions are there. ..

Smart antennas can focus adaptively to "lock into" a directional signal. Instead of radiating a signal in all directions equally, they figure out where a user is located and direct the radiation accordingly, reducing effective interference with other transmitters. Now, too, novel coding algorithms can take factors that traditionally hampered transmission, such as physical obstacles and motion, and use them to generate information that increases capacity.

Perhaps the greatest technological gain in wireless capacity, however, will come from systems that work cooperatively. In a network architecture called a mesh, each RF receiver also acts as a transponder, retransmitting data sent by other devices in the network. In other words, every new device uses some of the network's capacity but also adds capacity back. ..

Software radios are a key enabler for all these advances. A software radio can receive and transmit across a broad range of frequencies.. In principle, a software radio originally used for cellular telephony could, for example, download new software and begin to receive broadcast television signals, or, more likely, access a network that uses a new cellular transmission protocol. Even more sophisticated "cognitive radios" would work cooperatively, analyzing other nearby radios and adapting on the fly to avoid other transmissions. "

Combined with these technical advances are regulatory changes that will open up more raw spectrum to new uses.

  8:06:12 PM  permalink  

Spam Producing Nations and Drones: " Security firm Sophos on Thursday named a "Dirty Dozen" list of countries that produce the most spam. .. The U.S. took the dubious honor of top place, with 56.7 percent of the spam that Sophos trapped originating here. In comparison, the next worst nation, Canada, was the originator of a paltry 6.8 percent of the spam. Other countries on the list were China, South Korea, the Netherlands, Brazil, Germany, France, the U.K., Australia, Mexico, and Spain, in that order.

The rankings may be misleading, however, said Graham Cluley, a senior technology consultant at Sophos in a statement.  "Our intelligence suggests that a large amount of spam originates in Russia, even though it appears at only number 28 in the chart," Cluley said. "Hackers there appear to be breaking into computers in other countries and sending out spam via infected PCs," he added.  According to Cluley, more than 30 percent of the world's spam is sent from computers compromised by worms and Trojan horses which turn unsuspecting users' systems into spam proxies.

Several of the most virulent worms of late have been accused of just that tactic by security analysts. MyDoom, for instance, which holds the title as the world's fastest spreading worm, created backdoors on infected machines that some theorized would lead to a huge army of spam-ready systems. "

  1:01:45 PM  permalink  

The Disruptive Nature of Skype: "No it is not free telephone calls that are Skype's disruptive punch but free conference calls that obsolete current networks. "  Interesting speculation on the impact of free conference calling with presence and buddy lists.  Rather than substituting for telephony, some new function may be what brings voip to mass use.  12:00:05 AM  permalink  


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Last update: 5/16/2006; 11:34:14 AM.