Mobile gaming is extremely popular, but real-time multiplayer on a smartphone can prove to be challenging. That’s where Microsoft Research’s Switchboard comes in. Microsoft Research is no stranger to mobile computing or gaming, having created Windows Phone’s much lauded virtual keyboard and Xbox LIVE’s matchmaking service.
Switchboard is “a cloud service that enables smartphones to link to each other for multiplayer gaming.” Like Xbox LIVE, it “works as a ‘matchmaker,’ finding potential game players and assigning them to a group most similar for each player’s phone and network connection.”
Unlike consoles, smartphones have to deal with battery levels, switching between cell towers, weak signals, slow network speeds, limited bandwidth, and a lack of public IP addresses. Switchboard addresses all of these things, and it doesn’t rely on a specific device or network speed.
Microsoft Research had to figure out a way to reduce lag without placing a heavy burden on the network. Lag is caused when a player fails to receive information for a period of time. The game has to guess where the other players will be when the connection is restored, making it appear as if the players are jumping around.
The team at Microsoft Research discovered that “phones needed to be pinged about 60 times over a 15-minute period to collect reliable information. That places a heavy burden on the network, so the team also devised a method for using the latency of one phone to predict the latency of others.”
Other problems with multiplayer gaming include the scale of the market–hundreds of millions of devices–and the lack of public IP addresses. Only AT&T and Sprint offer them, with the former charging a monthly fee. Microsoft Research, however, believes more devices will receive their own public IP addresses once IPv6 usage increases.
Windows Phone Mango is rumored to support real-time multiplayer, but Microsoft has yet to say anything official. It’s a pretty good bet that the Switchboard technology will be added to Windows Phone at some point. We highly recommend reading Microsoft Research’s fascinating article.