Technical Difficulties from on Top of the Mountain
2004-04-21
  What cell-like handoff?
I've been using a 802.16 like product for about three years to get internet access at my house out here in the boonies via a 802.11b wifi card with chipped roms and a very tight beam antenna aimed 17 miles away at the tower on the mountain. Point to multi-point is a much different beast than baseless collision detecting catch-as-catch-can generic wifi.

Its been interesting participating in what has essentially been a three year experiment by one vendor to improve their proprietary solution (I think there were two firmware downloads yesterday, to what ends I have no idea). Back in the beginning it really sucked, only 2mbit total channel bandwidth and zero-nines reliability. Downtime was frequently hours, and occasionally days. Things are much more reliable now thanks to weatherproof antennas up on the mountain (good thinking for a facility at 11,000 feet) and every server box has hardware watchdogs and remote resets. The employees at Niles Radio got tired of driving the snow cat up the back of the mountain at 4pm in a snow storm when a box got stuck (a regular occurrence).

Still, I'm glad 802.16 (and 802.16a) is finally coming out and I would switch to it if it weren't for the possibly that DSL is going to finally reach out here in the forest. 2.4GHz has gotten awfully crowded and I have more faith in an industry standard than the experiment in process from a vendor I've never heard of. I find it funny however, that people are worried about making it support roaming "like cell phones do".

The original 802.16 specification did not specifically support mobility of client devices. It does have an adaptive PHY layer that can shift modulation schemes on a client-by-client and frame-by-frame basis. Given low ground speeds, this adaptation alone might be sufficient to sustain some mobility. However, there is no provision at all for cell-like handoff in the 802.16/a specs; a single base station is assumed at all times
First of all, battery life for a portable transmitter/receiver that has to reach up to 40km away is going to be pitiful unless we're talking about plugging into your car, but the comparison with cell phone service is flawed on the other side: assuming that data services from cellular providers can roam.

I don't know about GPRS, but I have used Sprint's CDMA data service in a mobile application: I spent two and a half hours on Amtrak from Chicago to Champaign doing web and chat on my laptop with a friend's hotwired handset. About once every 20 minutes the signal would drop off to zero and I'd get disconnected. I then had to "redial" and connect to another tower which was at full strength.

If that's the competition, then I don't think 802.16 (or 16a) has anything to worry about it.

 
Comments: Post a Comment

<< Home
Life in the middle of nowhere, remote programming to try and support it, startups, children, and some tinkering when I get a chance.

ARCHIVES
January 2004 / February 2004 / March 2004 / April 2004 / May 2004 / June 2004 / July 2004 / August 2004 / September 2004 / October 2004 / November 2004 / December 2004 / January 2005 / February 2005 / March 2005 / April 2005 / May 2005 / June 2005 / July 2005 / August 2005 / September 2005 / October 2005 / November 2005 / December 2005 / January 2006 / February 2006 / March 2006 / April 2006 / May 2006 / June 2006 / July 2006 / August 2006 / September 2006 / October 2006 / November 2006 / December 2006 / January 2007 / February 2007 / March 2007 / April 2007 / June 2007 / July 2007 / August 2007 / September 2007 / October 2007 / November 2007 / December 2007 / January 2008 / May 2008 / June 2008 / August 2008 / February 2009 / August 2009 / February 2010 / February 2011 / March 2011 / October 2011 / March 2012 / July 2013 / August 2013 / September 2013 / October 2013 / November 2013 / December 2013 / December 2014 / February 2015 / March 2015 / July 2016 / September 2016 / December 2016 / April 2017 /


Blogroll
Paul Graham's Essays
You may not want to write in Lisp, but his advise on software, life and business is always worth listening to.
How to save the world
Dave Pollard working on changing the world .. one partially baked idea at a time.
SnowDeal
Eric Snowdeal IV - born 15 weeks too soon, now living a normal baby life.
Land and Hold Short
The life of a pilot.

The best of?
Jan '04
The second best villain of all times.

Feb '04
Oops I dropped by satellite.
New Jets create excitement in the air.
The audience is not listening.

Mar '04
Neat chemicals you don't want to mess with.
The Lack of Practise Effect

Apr '04
Scramjets take to the air
Doing dangerous things in the fire.
The Real Way to get a job

May '04
Checking out cool tools (with the kids)
A master geek (Ink Tank flashback)
How to play with your kids

Powered by Blogger