Friday, February 26, 2010

X-Parameters--Nonlinear RF Component Characterization

X Parameters ( a registered trademark of Agilent) are nonlinear network parameters that represent a superset of S-parameters. They extend S-Parameters to work with large signals and non-linear regions for characterizing RF components. To gain access to the fundamental equations, one must sign up in Agilent's partner program.

A common application is the Load-pull measurement.

Best regards,
Hall T.

Friday, February 19, 2010

Wireless TestBeds

For those interested in testing out new wireless applications, the Federal Government under the Bush administration authorized the NTIA and FCC to set up a 10 MHz testbed in the 470 - 512 range as reported by the Benton Foundation. It's a common practice to carve out a portion of the spectrum to provide a testbed for developers. Clearwire did this with WiMAX in the Silicon Valley area.

University of Syracuse and Virginia Tech are leading the Wireless Grid Innovation Testbed (WGiT) with the goal of "coordinating knowledge sharing, defining key parameters for wireless grids network applications, dynamically connecting wired and wireless devices, content and users.

Another example is the Idaho National Laboratory established the Bechtel/INEEL Wireless Testbed. that offers end to end testing of next generation wireless including 3G/4G cellular and land mobile radios.

There's event a conference on the topic of building wireless test beds. You can see the current event here.

Best regards,

Hall T.

Friday, February 12, 2010

WhiteFI--WiFi Using Whitespaces

Microsoft is one of the players using the whitespaces to deliver wireless access. They call it WhiteFI which is similar to WiFI but has several differences. For one it uses an adaptive spectrum assignment algorithm to handle spectrum variation. They launched the KNOWS initiative which stands for Networking over White Spaces to resolve the fundamental networking issues related to setting up base stations and forming networks. They have gone from concept to deployed system on the Microsoft campus last October. You can see more details about the project here. Microsoft has even submitted an FCC license request to take WhiteFI into the field for further experimentation. They are working with Harvard on the research. You can see their paper here.

WhiteFI has a good deal of support behind it as it promises to spur innovation to the tune of $15B/year. One example of innovation is how it will bring wireless connectivity to ever smaller nodes in further distances. For example, irrigation systems could leverage WhiteFI for wireless connectivity.

Best regards,

Hall T.

Friday, February 05, 2010

SDR Applications

Software Defined Radio has been under development for many years -- primarily the military. In this whitepaper by Xilinx they position several applications on Geoffrey Moore's Crossing the Chasm model.

Smartphones follow Milcom and Satcom applications in the adoption curve. Some smartphones already use elements of SDR such as
Apple's iPhone 3G which uses the Infineon Baseband processor that has a reprogrammable DSP for baseband processing. Ericsson, Nokia, Samsung, and LG are also using similar chip sets and processing to achieve the benefits of SDR.

In the wireless infrastructure world base stations are now considered a commodity and thus price pressures require a common engineering platform targeted a multiple applications and air interfaces. ASICs can only go so far in achieving cost reductions. The next step is to apply SDR techniques. While on a single base station the cost of materials may be higher, that cost goes down when spread over several models.

In the coming years, more commercial applications spurred by the availability of spectrum without prior licensing will cross the chasm and start drawing more investment dollars.

Best regards,

Hall T.