Archive for May, 2014

 

Improving wifi in a crowded wifi environment

This is a litle trick I use when I travel and hook up to a wifi network in a crowded wifi environment. Sometimes the network performance over wifi is really bad and the problem is that it can be caused by heavy traffic (like file sharing) on another wifi network sharing the same channel as yours. I have experienced this especially when travelling to big cities like Paris, Amsterdam and so on. First of all, it is recommended that you disable 802.11n wifi mode which works terribly bad in crowded environments. See this article for Windows and this for Linux (Ubuntu).

 

Crowded wifi environment (Wifi Analyzer for Android)

Crowded wifi environment (Wifi Analyzer for Android)

The problem with the wifi technology is that networks in the neighbourhood is sharing the same channels. In the 2,4 GHz band there are only 11-14 channels availible (depending on your region) and those channels overlap. That means if your network is on channel 1 you will get interference with traffic on channels 1, 2 and 3. Another problem with wifi is that is has no means of evenly dividing the capacity (like timeslots), so it is kind “the one shouting highest gets the most bandwidth”. And when someone already is using a lot of bandwidth (like file sharing) it is very hard for other users to obtain a part of the bandwidth. Even if it is the neighbours wifi which you can’t access but it shares the wifi channel.

A countermeasure to improve the situation is to constantly use some bandwidth forcing the heavy users to pull back a bit. Before transmitting, each node in the network listens in the air if the channel is free, so by using a little bit of bandwidth even if idle you don’t give the other node the same possibilty to hog the entire capacity.

First of all, find out the IP address of your local network default gateway. In WIndows you run a command prompt (cmd) and type the command ipconfig. In Linux you can use netstat -rn.

To constantly use up a small portion of the bandwidth I use the ping comand. Ping normally sends very small packets (56 bytes), but to get this to work we need a bit larger packets (but not to large, then we will hog the entire capacity). 1024 bytes is good.

In Windows you run the command (replace 192.168.0.1 with the IP-address of your local network which you found out above):

ping -t -l 1024 192.168.0.1

and in Linux you run:

ping -s 1024 192.168.0.1

 

ping with 1024 bytes

ping with 1024 bytes

Voila! Now my wifi connection gets a lot more stable because I force the other wifi nodes to pull pack a bit since I constantly make them aware of my presence.

 

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Posted by on May 27th, 2014 No Comments

Install Ubuntu 14.04 on Samsung Ultrabook Ativ Book 9

To install Ubuntu 14.04 on a Samung Ultrabook Ativ Book 9, this is how to do it.

I decided to keep the factory installed Windows 8.1 beside my Ubuntu install using dual boot. Thanks to enrish for the basic info. I found out there is no need to shrink the Windows 8.1 partition as long there is space enough for Ubuntu. The Ubuntu installation will do this for you. Before you do anything – make sure you have a backup as usual. If you decide not to keep the Windows 8.1 install, do keep the recovery partitions. No need to install any screen drivers, Ubuntu worked out of the box.

  1. In WIndows, run the Samsung Update Utility and update everything including BIOS/firmware.
  2. In Window Control Panel go to Power options and click on Choose what the power button does. Click on Change settings that are currently unavailable then scroll down and deselect Turn on fast startup (source http://askubuntu.com/questions/221835/installing-ubuntu-on-a-pre-installed-windows-8-64-bit-system-uefi-supported). Restart your system.
  3. When booting, press F2 to enter the setup.
  4. In the Boot section, disable Fastboot
  5. Insert the USB flash drive with Ubuntu ISO (prepared with create startup disk on another computer). 
  6. Configure boot device order, setting the flash drive to be the first option.
  7. Save and reboot. Now the system should be booting on the flash drive.
  8. Select to Install Ubuntu. During installation Ubuntu will recognize that you have Windows 8.1 installed and you have the option to install Ubuntu beside the Windows 8.1. The Ubuntu install will shrink the Windows 8.1 partition to make room for Ubuntu. By dragging the vertical bar you can decide how large the partitions for Windows vs Ubuntu should be. Continue installing Ubuntu as usual.
  9. After installing Ubuntu, unplug the flashdrive and when booting, press F2 and enable Fastboot again.

 

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Posted by on May 20th, 2014 5 Comments