Using EVDO with VOIP, Streaming Audio or Video |
| Saturday, 26 February 2005 | |
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There are different ways to use your internet connection. Most of the times, when you are doing email or web browsing, your email client or browser opens a connection gets some data and closes the connection. Other times, like using Instant messaging, or FTP'ing, the connection is persistent. That means, once the connection is open, the connection does not close down. Using screen sharing software (VNC, Timbuktu, Remote Access, etc), also uses persistent connections. Also, VOIP por any type of video or audio streaming uses persistent connections. What happens, when you have software that uses a persistent connection and you are driving around and you switch cells, we did an experiment using iTunes to stream a radio station (a persistent connection). Below are the results.
The test. We were in a 1XRTT (nationalaccess) area and we started to listen to a 56K audio stream using iTunes. In our area, we know were the EVDO coverage starts and ends. So, we drove into an EVDO area to see what would happen to our connection. Would the connection drop, which is what we expected. The good news, is that the connection did NOT drop. It streamed without dropping at all. The bad news. The connection did NOT switch to EVDO, it stayed at the slower 1XRTT speed, even though we were in a EVDO area. So, if you start off with a 1XRTT persistent connection and move into an EVDO area, you will be locked into the slower speeds - even if you are in an EVDO area. Once, we quit the software the connection did NOT switch to EVDO (like it normally does), however, disconnecting and reconnecting to the network, did give us our EVDO. PLEASE do not use EVDO for VOIP, if a lot of people do this, performance will suffer for all users. If you are new to VOIP and want to find out what you can do with it (it is very cool), check out VOIPInformation.com. The next revision of EVDO, named EVDO Rev A, will be faster and contain some enhancements for video and VOIP. Currently, the EVDO upstream connection is throttled back to 80 - 110K, which isn't enough for a 2 way video chat. I think Verizon did this on purpose, since a handful of people doing video chats could affect performance for everyone else using the same tower. We did try a 2 way video chat in October 2004 and it didn't work. However, it did work when we did a one way video chat (seeing the remote party, but they cannot see us), that worked because we only were using download vs. upload. This was so cool, there was an article in the Las Vegas Sun newspaper about this (read it here). Update. Since, the EVDO card has 2 channels (1XRTT and EVDO), it actually makes complete sense, once there is a 1XRTT connection, and it is persistent, it will not automatically be dropped for the EVDO one. Although all this is possible, please see Verizon's Terms of Service for more information. Related Articles: |
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Mac EVDO
