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Android Tethering

Having a phone with a data plan allows you to tether other devices, computer, tablet, another phone etc and use the same data connection. This saves having multiple data plans. Android is VERY flexible in terms of how to tether your devices. Each have pros and cons. It will be up to you to figure out what works best for you. The phone I have is a Droid 2 Global from Verizon running stock Android 2.3 but rooted. Rooting allows me to load and play with different tethering applications.

I will state up front tethering takes a surprising amount of horsepower out of your phone and thus has a dramatic impact on battery life.

For comparison purposes I used Speedtest.net’s Android Ap and obtained 4347 kbps down and 1209 kbps running on Rogers 3G network sitting at my desk in Toronto with full bars (83%) of reception. If I wanted to be scientific about this I would run the test 10 times and average the results. Since I have a life … I will skip this 🙂

USB tethering is built into the Android OS and there is nothing to do but plug your phone into your PC and enable USB tethering on the phone. On my device it’s under settings, wireless networks, tethering, USB tethering. On the Windows side a virtual network adapter get’s loaded in and then that get’s an IP address and your done.

I used DSL reports to test the speed:

Using raw numbers this is 21% slower down and 29% slower up. USB has the advantage of maintaining the battery to some extent while tethered. If your running an operating system other than Windows you will need to find that virtual network card driver for your OS.

Next up you can use WIFI tethering. This is by far the most flexible way. The Android phone simply acts as an access point sharing out the internet. This works very well but takes more power especially if you turn on encryption. The ARM processors seem to be particularly poor at encryption algorithms and beat the crap out of the CPU and thus battery life. Of course the downside of using no encryption is that anyone around you could be using your connection too so this is something you need to watch. You can limit the number of devices and even allow only certain clients to connect.

This also uses the WIFI on the phone which also consumes power. With encryption tuned off and using the native tethering ap I obtained 4644 kbps down and 1128 kbps up which is 7% faster on download and 7% slower on upload. Obviously this is nothing more than variability on the speed test. The CPU while serving was sitting around 40-60%.

Turning on WPA2 using the native tethering ap got 3512/1137 kbps which is 19% slower down and 6% slower up. The CPU interestingly did not seem to be much busier. Battery life on WIFI tethering would be about 5 hours on my Droid 2 Global.

You do need to turn on WIFI tethering on your phone so it’s a manual step.

Last up is connection by bluetooth. This is something I worked on for a while before I got running. I found this bluetooth tethering thread that helped. For whatever reason on my phone pairing by bluetooth for the purpose of tethering totally pinned the CPU on the phones. From the moment it connected to the moment it disconnected. So while you save on WIFI power you loose on CPU. Bluetooth is also bandwidth limited so will be a bottle neck to your internet speed. On my device I had some issues with reliability of bluetooth tethering if you had used WIFI tethering which ended up requiring a reboot of the phone to clear up. No idea why. I was able to get 1443/1107 kbps which is the bottle neck imposed by the bluetooth interface. This is 67% slower on download and 8% slower on upload. Bluetooth bandwidth is 1Mbps for BT 1, 3 Mbps for BT 2 EDR and 24 Mbps for BT 3. Most phones today only have BT 2 EDR. BT on wikkiedia.

Of the phones I tested Droid 2 Global from Verizon running Android 2.3 and Droid Pro from Sprint running Android 2.2 supported Bluetooth tethering. HTC Desire Z from Bell running 2.33, HTC Nexus One running 2.36, Samsung S2 LTE from Rogers, and LG Gossip Pro running Android 2.35 did not. The bluetooth profile the phone has to support is called DUN (dial up networking).

I did a test of my Droid 2 and I figure I could get 5 hours on bluetooth tethering on a full charge so about the same amount of time as WIFI.

The other up side of bluetooth tethering is you can initiate it from the tablet itself without having to touch the phone! Of course the bad thing is that if you walk away from your phone it disconnects and does not automatically reconnect. And range is shorter than WIFI.

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January 25, 2012 - Posted by | Android

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