Ping depends mostly on distance and routing, not bandwidth (speed).
Many factors influence ping, since you mentioned this is a 4G connection - it could be due to your distance from the tower. Other factors include: network routing (how they send your traffic to the server), distance from the server, type of connections used and their overheads, congestion on the tower or server you're testing to...the list goes on.
Also, ping will vary depending on which server you test to. Just because you have a 90ms ping to one server, does not mean you have 90ms ping to every server or device on the internet. International servers/routers are normally 150+ms.
Edited by NpaMA, 18 June 2012 - 07:32 PM.