Ok here is what I found out in terms of the wifi sleep policy. Default setting is set to 15mins. WHen the phone goes to sleep and if it has been in sleep for longer than 15 mins wifi will turn off then switch over to mobile network data. Now some say wifi uses less power than mobile network, In my case thats true because in our office building we do not get good mobile network so 3g/4g go in and out and then at times to no services..THIS DRAINS MY BATTERY. So now using the wifi network at work, I turned the wifi sleep police to NEVER so it will constantly stay on wifi. And I am now seeing better battery. (atleast slightly..it helped)