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How Matchmaking Works- From Activision


One of Swords just linked to this article on support.activision.com about how matchmaking works. Thought you all might find it interesting since there is a lot of discussion about how this works. Thoughts? Would respectfully ask that we have a discussion, and not a rant session.


Do you think it works? Does this explain things to you or do you still have questions? Do you have ideas for how to improve matchmaking?


http://support.activision.com/articles/en_US/FAQ/How-does-matchmaking-work-in-Pu blic-Match/?l=en_US&c=Game_Title%3ACall_of_Duty_Black_Ops_II&fs=Search&pn=1


Note: This article is intended to dispel some of the mysteries surrounding this feature, as the matchmaking process happens largely behind the scenes. The article does not cover the skill-based matchmaking of League Play, which matches players more strictly on skill rank.

The first step in the matchmaking process starts at the playlist level. Playlists divide players into collections of maps and gameplay rules. Playlists are a set of rules that form a mix of gameplay experiences and should not be confused with game modes. The specific collection of gameplay rules defined in playlists can change over time based on the changing tastes of the online community.

Once a playlist is chosen, the game starts the search for the best match within the playlist’s population. Playlists will typically range in population from 500 to 100,000 players around the world at any point in time. The number of available games in a playlist is around 10-20% of the total player count. At the lowest end, for example, a playlist of 500 players may have only 50 possible games from around the globe to join. The search query takes the list of all available games and filters it down using these steps: 

  1. Filter all games that can be joined by proximity to the player. Proximity does not adhere strictly to city, state or country as seen on a map. Rather, it breaks down into four tiers of geographical region surrounding the player. The query starts in the tier closest to the player and expands from there if it cannot find enough matches. The query also ignores all full or “non-joinable” games, which could be half or more of the total available games in a playlist.
  2. Filter by broad skill range. This step takes the proximity-filtered list and narrows it further to the set of games that fall roughly in the same broad skill range. This is very loose criteria in Public Match and is a broad-stroke filter that avoids games at the extreme ends. A player of very high skillshould generally not get matched to games where the average skill of players is very low, and vice versa.
  3. Steps 1 and 2 normally take a fraction of a second and result in a list of “top 50” available games. From here, the game tests for the best connection quality of those 50 games. Connection quality includes a measure of ping, bandwidth between you and the host, and NAT compatibility. The game attempts to join the you to the game with the best connection quality of all possible matches, starting at the top of the list.

Note: The total process of all three steps could take several seconds, depending on your connection to the internet and the games available in your playlist and region at that point in time. In the best-case scenario, you should get matched to game hosts in your region, where the average skill is not at an extreme above or below your level, and where the game is the best connection quality you can find.

There are several factors that can decrease the quality of matchmaking and degrade the quality of your online matches:


  • The first is your local network connection quality which itself is determined by a number of variables. If the quality of your network doesn’t meet minimum criteria, the matchmaking won’t matter – the game cannot control variables that are general aspects of internet connectivity. For steps on improving your local connection quality, see the article on decreasing lag. Here are some factors that can decrease your quality of network service: 
    • Low bandwidth to the internet due to ISP bandwidth limits.
    • High bandwidth usage by other services in your home (video/audio streaming or high-volume concurrent downloads, for example).
    • Your local home network has restrictive NAT settings.
    • You are playing the game over a WIFI connection rather than wired Ethernet.
    • Your ISP is throttling data throughput from your location. Some ISPs erroneously flag online games as “spam” and will throttle the speed at which data can transfer in and out of those games. If you experience consistently laggy games or games that lag during the same time periods every day and there are no other problems with your home network, check with your ISP to ensure that they aren’t throttling specific types of data.
  • The second variable is your region. If you live in a remote region, it will be more difficult to find hosted games that match your profile. The best option for those in extremely remote regions is to play during local peak hours in playlists with high player counts.
  • The third variable is time of day. Since matchmaking works to find the game with the best connection quality, it will have a much easier time finding high quality connections when there are more players online in your area. As a general rule, peak usage occurs during the late afternoon and evening hours in each time zone.
  • One last variable to be aware of is DLC. DLC map packs divide matchmaking pools into groups of players who have DLC and players who don’t have DLC. The more map packs that are released, the more matchmaking pools there are. Nine months after the initial launch of the game, for example, the highest single population of players is that which owns all map packs.

Now that you understand how matchmaking works, you know what factors contribute to the quality of games available to you at any point in time. If you frequently find yourself in games with lag, first check your local internet settings for ways to improve performance. Then, check with your ISP to make sure they aren’t throttling bandwidth. If your internet and home network are both in good shape, but you still find yourself in games with lag, you may want to schedule your online sessions for times of day when there are more players online in your location, typically late afternoon and evening.


The game also provides the option to change matchmaking search preferences to favor getting into games faster (which may result in lower-quality network connection between you and the host) or getting into better-quality games (which may extend the time it takes to find games). In the “Find Match” selection screen, press the button labeled “Search Preferences” and select your preference: “Normal” (default) follows the exact steps outlined above; “Any” reduces restrictions in the query and will return results faster, although they may not be the best results; “Best” increases requirements for connection quality and may result in longer search times.

  • 1. Re: How Matchmaking Works- From Activision

    The article makes perfect sense to me on how it works and why sometimes some people get better or worse games than others at times.

  • 2. Re: How Matchmaking Works- From Activision

    Very informative post. Thank you for the info. I'm not sure how much it will stop the lag talk, as many think it's never "Their" fault to begin with.

  • 3. Re: How Matchmaking Works- From Activision

    I found it very interesting myself. I think it was a very frank, informative article.


    Honestly, we complain about it a lot but I know it has to be a tremendous undertaking. Internet connections are so varied now, much more so than when COD4 was out, that it has to be tougher than ever to effectively matchmake. The part about the ISP throttling was particularly interesting, and I bet a lot are effected by that.

  • 4. Re: How Matchmaking Works- From Activision

    So the entire United States is region 36. So I can be matched with someone 3500 miles away in the first filter results. Ping is at the bottom of the totem pole. Of course its the least important. Skill level is much more important than ping????? Why would you not start the search with ping and go from there?

  • 5. Re: How Matchmaking Works- From Activision

    1.Filter all games that can be joined by proximity to the player. Proximity does not adhere strictly to city, state or country as seen on a map. Rather, it breaks down into four tiers of geographical region surrounding the player.


    ^^^That's the bit that needs tweaking the most imo. Good to see they're listening and getting info out there though.

  • 6. Re: How Matchmaking Works- From Activision

    So it isn't by magic then?

  • 7. Re: How Matchmaking Works- From Activision

    Where did you get the Region info from? Didn't see that in the article.


    I don't think you are correct about the ping. It matches by region first, then by skill. It then attempts to find the best lobby to place you in based on variables in that lobby, including ping. It has to know where you are needing to go before it can get you there. The ping is part of that as explained in the article. Remember, ping is just part of the equation in connectivity.


    So, basically it sees Nubdub is from X region and falls into Y skill level bracket. He wants to play this specific game mode and creates a list of joinable games based on that information. The search then attempts to find the best match based on that information and by checking for the best connection possible based on Ping, NAT, and bandwidth. That is how I understood it, at least.

  • 8. Re: How Matchmaking Works- From Activision

    The regions are obviously too big. In Blops1 every lobby was pretty much people from the same state as me. Now it seems like it's hardly anyone.

    It seems like that maximum ping it will think is okay to match you with is way too high.

  • 9. Re: How Matchmaking Works- From Activision

    I cannot complain about the system because I believe it places connection first. What it cannot do anything about is parties which will have people from varying regions with various pings to the host. Impossible to do anything about that. If you play a game where parties are not allowed you would probably notice that the spm will vary greatly among players as it seems to prioritize the connection first and then player skill. Just because people don't have the little party symbol near their name does not mean they aren't playing together.

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