Fixed bug:
Under the no network situation, the track service will throw exception and closed. So every time the user lost the connetion, user has to restart the service again which makes no sense.

Solution:
Everytime the client wish to use the network, it has to check the avaiablity first. If not network found, the package will actually be throwed away which makes sense somehow. Because, we don't want to aggregate too much info in the user's phone.