Packet latency on CDMA 1X network

Hi,

I recently got a phone for a network that uses 1xRTT CDMA 2000 (Reliance Infocomm in India). I found that while the downloads were acceptable (from 7-9 kbps), the interactive sessions like HTTP are VERY slow. A traceroute from my PC to yahoo showed that first hop latency is as high as 1.3 seconds!!! I repeated the test with some load on the link after I read that a 9.6kbps channel is dedicated for each link and more are requested as the need arises. Got similar results with VERY high first hop latency which is always above one second.

So can someone tell me what latency is to be expected from a CDMA network?

Thanks,

- Siddhartha

Reply to
Siddhartha Jain
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Unfortunately for this type of radio interface, this is typical. I generally get betwenn .8s and 1.4s latency, with a throughput of between

90-120kbps on the SPrint PCS network in the US (which is currently 1xRTT, migrating to 1xEV-DO). A lot of it has to do with the fact that the first "hop" goes through the air interface which can be a distance of between half a mile to three miles or more, and then through the cell site to the MTSO, which may or may not act as the first router in the path. That's a pretty significant hop!
Reply to
Isaiah Beard

300-400ms. We

EVDO ... Mmmm ... will sure wait for that. In the meanwhile, I am sure the Reliance guys need to seriously tune up their equipment and expand capacity. Downloads are are as slow as 1.9kbps. The reason, I suspect, is that there aren't enough channels to allocate to a single user for multiplexing them in a bigger pipe. I keep a watch at the phone display and observed that the data rate frequently falls to "9.6" so the network isn't giving me a sustained throughput. Daytime is worse than nighttime so there definitely is a capacity issue.

- Siddhartha

Reply to
Siddhartha Jain

I will say that we have rolled out Verizon CDMA EV-DO cards for about 100 people in our sales force. The latency we're seeing is about 300-400ms. We also see about 500ms in 1XRTT mode. Since the Reliance equipment is Lucent they should be able to "tune" that somewhat. The natural upgrade path will be EV-DO for that network so just give it some time.

The download speeds seem consistent with what we've seen here in 1xRTT mode. When you get to EV-DO you'll see about 300-500 kbs.

Compare this with 800-900ms latency we've seen in testing EDGE cards (between GPRS and UMTS).

Regards,

Mark

Reply to
Mark Tanaka

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