When milliseconds are a matter of (virtual) life and death
Posted on June 6, 2017
4 min read
There are industries, like the infamous high-frequency trading, where shaving milliseconds off the latency of your network connection is worth tens or even hundreds of millions of dollars. In the coming era of remote-controlled haptic robots, latencies will also be critical.
But even today, every day, latency is a matter of life and death for thousands of Australians.
A matter of virtual life and death, in this case.
What is latency anyway? In networks, latency is the time it takes for information to be sent between two points. The measurement usually used for this is the so-called RTT time (round trip-time), the time it takes for a signal to be sent plus the length of time it takes for an acknowledgement of that signal to be received.
And in the world of online gaming, RTT is one of the network performance measures that matters a great deal.
Whether you’re into the free-roaming adventures of World of Warcraft or learning the ropes of interstellar economy in Eve Online, there’s now a massively multiplayer online game for everyone.
Different type of games have varying network performance requirements; strategy games tend to be much more forgiving, whereas for obvious reasons FPS (“first-person shooter”) games are more demanding.
And herein lies the catch: to a degree, depending on how the games are architected, a player with a worse RTT performance on his or her connection can be at a significant disadvantage when playing these games.
How low is low enough then? It depends, but the following can be used as a guideline for RTT times as measured to the gaming server:
- Green (good gaming experience for all genres): < 80ms
- Yellow (mostly ok but can have some issues): 80-150ms
- Red (major issues with more demanding games): 150-200ms
- Black (unable to play demanding games): > 200 ms
Now, the overall RTT latency is comprised of a number of elements, many of which are outside the user’s control. These are factors like serialization delays and the specific routing the packets take, the switching involved, as well as queuing and buffer management algorithms used in the network equipment. The most obvious impacting factor is distance – in the case of gaming, the distance from the gaming server.
The Melbourne-Sydney latency is only slightly more than 10ms, but Sydney-Perth is already close to 50ms; double this – as can happen simply from using Wi-Fi in poor conditions – and you’re already past the “green zone”. An Australia-US link will add over 150ms.
As mentioned, one surprising element can add to the latencies at home, too: Wi-Fi. In good conditions Wi-Fi will only add a few milliseconds of latency, but can add as much as 30-50ms in ‘noisy’ conditions such as an apartment building where many Wi-Fi routers operate close to each other on the same frequency.
The type of broadband connection you have also has an impact; a fibre optic connection is best, followed by other technologies – wireless can add significant latency, and a satellite connection adds sufficient latency that real-time gaming can be challenging at best.
What about mobile? A good-quality LTE (4G) connection should be just fine for games, with ping times roughly 30ms in good conditions, although this can vary with your location and the device you’re using. Even the more limited data quotas available on mobile are not usually an issue with many games using as little as 5MB/hr.
As 5G rolls out with much-improved latencies, the network performance may even surpass many fixed connections in its latency. According to Ericsson, 5G should allow low-level end-to-end latencies of 1ms or less; even at an order of magnitude greater application level latencies, 5G would compare favourably against most other access types. For a wireless connection to do that is something that would’ve been unthinkable some years ago.
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