Fall 2006 Issue


What is Happening to the HSMM Working Group?

By John Champa,* K8OCL

At its January 2006 meeting, the ARRL BoD directed that the HSMM (High Speed Multi Media) Working Group summarize its accomplishments and submit its final recommendations by year’s end. With that directive in mind, and with dissatisfaction within the Working Group regarding how its recommendations concerning permitted radio network protection methods (e.g., encryption) for the Amateur Radio Service are being communicated by the League, most of the group members simply left.

The ARRL HSMM website (http:// www.arrl.org/hsmm/), which has been in operation for the past five years, has been transferred to the Technical Information Services (TIS). However, the HSMM public discussion reflector (ARRL-80211B@listserv.tamu.edu) remains in full operation.
Some of the Working Group membership who left have since formed a new digital radio networks research organization, the Amateur Radio Broadband Alliance (ARBA) in association with Texas A&M University in College Station, TX. More on this new organization will be covered in this column in the next issue of CQ VHF.

What is 802.16 (WiMAX)?

According to its web page “The IEEE 802.16 Working Group on Broadband Wireless Access Standards develops standards and recommended practices to support the development and deployment of broadband Wireless Metropolitan Area Networks [that’s WMANs vs. WLANs covered by 802.11 standards, i.e., more range—ed.]. IEEE 802.16 is a unit of the IEEE 802 LAN/MAN Standards Committee, the premier transnational forum for wireless networking standardization.”

The following is a report from the HSMM Working Group Project Leader for 802.16 investigations, Gerry Creager, N5JXS (e-mail: <gerry.creager@tamu.edu>) of Texas A & M University:

We’ve installed a Solectek link here at TAMU. We’re operating under both Part 97 and Part 15 for testing in the 5.7 GHz region. So far we’ve deployed a point-to-multipoint installation and are working with a point-to-point operation over a 3 mile path.

We’re achieving data rates of up to 72 Mb/s on the point-to-multipoint configuration, and we’re locking at 36 Mb/sec on the point-to-point link for political reasons. Note that this experiment is co-sponsored by the university’s campus networking folks, so the Part 15 stuff is highly subject to politics.

The Part 97 aspect is being tested in concert with AG5GY. His was the first link up, at about 2.8 miles. The client end uses a panel antenna with 24 dBi gain and a 9 degree beamwidth. Power output on the clients is 100 mW. It’s mounted about 14 feet off the ground. There’s a clear line of sight to the base.

My house is 5.0 miles from the base, in a hole, and behind some 40 foot tall oak trees. This is a real test of non-line of sight (NLOS) wireless technology. I’m seeing marginal signal but we’re getting 72 Mb/sec most of the time, and even with excessive retries, the performance is pretty good. I’ll be expanding into voice-over-IP (VoIP) and video soon to see about packet loss, jitter, and congestion in the face of real applications.

The base unit produces 400 mW. We’re using a 27 dBi panel with a 90 degree beamwidth. All polarization is vertical. The base is mounted at approximately 240 feet AGL . . . and about 550 MSL. That places it at about 200–220 foot height above average terrain (HAAT).

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