Just moozing

Before you can check your notes, you must make them…

Wireless sucks – a story of an 18th century building

leave a comment »

I have been working with wireless in the past couple of weeks, and I conclude as always that wireless is overrated 🙂

It has been a terrible week from a technical point of view. There were three things I wanted to do

  • Get my USB DVB-T device
  • Set up an extra wireless AP so the building was well covered.
  • VPN access

DVB-T

The USB DVB-T device is a small Sandberg device usable to receive digital TV and radio. It is well supported in Linux and I had no special problems. I am planning on combining it with gstreamer – but that is postponed for now 🙂  More on that part in a later blog post.

Everything worked well in Denmark, but in France no luck. It simply did not find any channels.

In order to improve the reception, I searched and found this site on TNT (Télévision numérique terrestre, i.e. DVB-T). I told me to point the antenna S-by-SE. So I moved the antenna to an upstairs window turned (mostly) SSE, and I started to find channels.

I also got some weird error messages, which obviously wanted to google, but there was no wireless coverage in that part of the house. Since this sort of debugging requires a certain number of research-test-debug cycles, I would have taken forever if I were to moved around the house all the time. My conclusion was to continue with the DVB-T device once I had proper wireless coverage.

Wireless AP

We had a D-link DIR-615 (rev. D4) in stock and a look on the Openwrt site, showed it should run Openwrt nicely.

Initial plan:

  • Find a (reception wise) good spot and set up the router as a WDS client and connect to the main wireless network
  • Broadcast a second wireless network with the same ESSID to make it transparent to the user.
  • Install VPN (and make a port forward) to connect from the internet

I have worked with WDS before, most wireless chips supports multiple WLANs and VPN is just about installing the right packages on Openwrt. Considering the title of this blog entry, it obviously didn’t according to plan. Besides that, I had forgotten that I tried OpenVPN before

Setting up the router

Installing Openwrt on the router was surprisingly easy. It worked with the default attitude adjustment binary as described in this forum thread. It even has an “emergency room” webpage for flashing the system. Very cool.

WDS was not possible. It requires having good control of both ends of the bridge, and I can do fun stuff at one end.

Alternate plan to WDS, is to make the router access the wireless network as a client. It is easy in the GUI and well supported by Openwrt. Luci has a “scan” button – and it showed no networks what-so-ever. My laptop located ½m away found 6 or 7. After been frustrated for a while, I decided to take the router to a different room – then I started to find wireless networks. The conclusion was that the antenna on my laptop is way better than the one in the router. I should to look into antennas some more.

Having changed rooms, I was able to make a cabled connection through the router to the wireless network.

Next, configure the router to broadcast a wireless network. This is trivial also in the GUI.

Except the router could not work with two wireless networks at the same time. It seems to be a hardware limitation.

And installing VPN, gave me an error about the lack of space on the device.

The solution

Needing new equipment anyway, we decided to go for ethernet-over-powerlines. It works well, the newer standards are quite fast and the price is the same a new router. The bad part is if you try to connect to sockets that are on different phases or if they are separated by a fuses/meters/whatever.

We settled on these from TP-link. They should able to do 200 Mbps. There is also something about security, but I did not look into that yet. They follow the Homeplug AV standard, so connecting a third (possibly non-TP link) device should be possible.

The D-link router is now running as a simple AP at the other end of the house and broadcasting the same ESSID wireless network as the original network, and we have good coverage in the entire house.

Conclusions

  • The D-link router is probably good for some things. Not my things.
  • Having 60 cm walls is very bad for wireless systems.
  • Old houses have only one phase for power – this is good for powerline ethernet.
  • A raspberry pi will handle monitoring, VPN and whatever else I want.

 

Advertisements

Written by moozing

July 27, 2013 at 09:00

Posted in Tech

Tagged with , , , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: