Tactical .75 pants

Saturday, April 30, 2011 Posted by

So here’s the deal: I’m looking for some pants that keep you a bit cooler in the summer than the original tactical pants, or even the lightweight tacticals. Blackhawk! and 5.11 both provide a series of shorts, but those are not really my thing. I’m more of a three-quarter length pants, that go just over the knee. If at all possible I’d like them so that the kneepads still fit. Read the rest of this entry »

Samba init script gone?

Friday, April 29, 2011 Posted by

Whoah, don’t know what happened but the start/stop script for samba in /etc/init.d was suddenly gone. Don’t know if this happened during the upgrade to Natty Narwhal (11.04) but here’s a fix: Read the rest of this entry »

Upgrading Ubuntu Server to 11.04 using SSH

Thursday, April 28, 2011 Posted by

I run a server at home (see NAS: Ubuntu Server on Intel ATOM) to, among many other tasks, backup the websites I run (see Backup your website using curlftpfs and rsync). Running at a meager 35watts, I figured there’s room for improvement. And there is, as Ubuntu 11.04 with Linux 2.6.38-8-server kernel is supposedly more energy-efficient. This morning 11.04 became available and I wanted to do a dist-upgrade. Problem: I was at work. Luckily, SSH helps here! Read the rest of this entry »

Highlighting in the LaTeX Verbatim environment.

Wednesday, April 20, 2011 Posted by

You want to show some output (say an event trace) and want to highlight certain passages. LaTeX’s verbatim environment is a nice and quick way to format this, but you cannot do any fancy tricks. The lstlistings package comes with syntax highlighting for various programming languages. But it’s not code we’re showing, its basically raw data where we want to highlight some important section. How’d we do that? Read the rest of this entry »

Wrong duration of SlotTime in IEEE 802.11p in NS-2 / NS-3

Wednesday, April 20, 2011 Posted by

IEEE 802.11p is designed for use in the V2V / V2I context. It uses an OFDM physical layer largely based on IEEE 802.11a. Some values are directly reused, others are modified. The slottime (often denoted with the Greek ‘sigma’ or aSlotTime) is one of those values which are unclear.

As a result, NS-2 and NS-3 erroneously use a wrong 802.11p slotTime of 13 microseconds. Scientific works using these simulators should carefully check sensitivity to this bug – results may be off!
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