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xenophon

join:2007-09-17

1 recommendation

Latency matters more after a few Mbps

That's good speed but the 100+ms latency is not all that great. A smartphone app only needs a few Mbps, after that, lower latency matters more.


SysOp

join:2001-04-18
Douglasville, GA

1 edit
+1

and that latency is on a rather unloaded network too. It's not going to get any faster once subscribers migrate to LTE.

xenophon

join:2007-09-17

1 edit
Many Sprint/VZW LTE sites are getting 50-70ms even with some load. But yeah, 100ms+ for a new site is not all that great. Maybe it's just a matter of tuning.


jmn1207
Premium
join:2000-07-19
Ashburn, VA
kudos:1
reply to xenophon
It depends on the app, I suppose. With my SlingMedia player app, I can suffer through 100ms latency without issue, provided the download speed is steady at 1500+ kbps.

I'm also streaming 320 kbps music throughout most of the day, and the latency does not appear to be that critical to either MOG, Spotify, or Google Music apps.

Only voice and video call apps would significantly suffer that I am aware of, but are there any other apps that might rely on a very low latency? It's not like 150ms is terrible, just not perfect for online games or VoIP applications. Are these heavily used by most smartphone users outside of a WiFi range?

I did a few speed tests from various servers listed nearby. The results are a bit sporadic, so I'm not sure how telling these tests really might be.


Speed Test from Various Servers Nearby

xenophon

join:2007-09-17
That's interesting that ATT bounces around latency like that. I'm getting more consistent latency on Sprint...

»dl.dropbox.com/u/3812896/Pics/An···tlte.png


jmn1207
Premium
join:2000-07-19
Ashburn, VA
kudos:1
I'm using Verizon, and the tests were from different servers within a 50 mile range that were available.


XANAVirus
Premium
join:2012-03-03
Lavalette, WV
Reviews:
·Callcentric
reply to SysOp
+1

I'd be interested in seeing a traceroute done from the LTE network.
If it's anything like my HSPA+ AT&T connection, before you even get out onto the Internet you have to go through 12 AT&T router hops.

The LTE network's latency is barely lower than the HSPA+ network (which usually rides at 120-200ms).

xenophon

join:2007-09-17

1 edit
I just did Sprint LTE traceroute in Android app, with about 60ms latency.

As expected, the link from cellphone to tower has most of the latency, not between cellsite and destination. If the cellsite is also using microwave or something wireless, it may then add more latency. It took 10 hops to get to Google but most of the bottleneck in latency is mostly phone to cellsite.

en103

join:2011-05-02
reply to XANAVirus
I'll go out on a limb and state that LTE and HPSA+ are riding the same backhaul for most of AT&T, which in that case, may be not enough.

en103

join:2011-05-02
reply to xenophon
That's about what I typically see as well. The site that I typically connect to is microwaved HPSA+ (no LTE by any carrier here).

en103

join:2011-05-02
Reviews:
·Time Warner Cable
reply to xenophon
Probably a lot less users (in general) in any given mile on Sprint.
Many AT&T phones (Android /WP and iPhone 5) are HSPA+/LTE.

Sprints newer phones are both - question is - how many Sprint users are on LTE in your area, and what is the cell density like ? I'm sure that VZW has a high percentage of its data users on LTE.

Some of AT&T's markets (Like SoCal) have 6MHz x 2 for LTE, which isn't a whole lot, especially when they're using 20MHzx2 for HSPA+.

xenophon

join:2007-09-17
said by en103:

Sprints newer phones are both - question is - how many Sprint users are on LTE in your area, and what is the cell density like ? I'm sure that VZW has a high percentage of its data users on LTE.

That leads to a good point though. Given that Sprint LTE is on 1900 it means there is more density of sites so you are likely to be closer to a tower and have fewer users per tower, especially since Sprint has half users of ATT/VZW. ATT/VZW are doing LTE on 700Mhz so a tower may be further away, which impacts latency (and supposedly 700Mhz is susceptible to interference more than 1900). Downside to 1900 is distance so needs more sites but that means since sites are closer together, you are likely closer to a site so you're likely to get lower latency. So there may be more variance in latency on 700 LTE than 1900 LTE - can't speak for HSPA+ on 1900, maybe protocol slightly less efficient.

en103

join:2011-05-02
Reviews:
·Time Warner Cable
That is correct - until AT&T implements AWS spectrum for LTE - or recycles GSM/HPSA+ spectrum it will be short on capacity - especially in markets that it doesn't have 12x2 700MHz (like VZW does - eg. SoCal).
Sprint already has high density on 1900MHz - so it should perform well.