GSM will win most in battery efficiency due to it being a TDMA based standard that pulses the radio off and on. But LTE has improved a long way since the early days.
To summarize pre-2012 HSPA:
- Basically, HSPA phones until around 2011 or so stayed in a higher power state much longer than they should have.
- People got pissy about having crap battery life.
- Manufacturers responded by doing proprietary hacks to send modem into lower power state.
- Cell networks essentially got DDOS'd as phones sent nonstop signaling to negotiate different power states.
- Phones now not only got poor battery life, but also barely operated on the now congested network.. remember the at&t iphone monopoly days before 2012 in major cities, it was a bad time.
3GPP Rel8 came about to fix the issue for good by moving power state control to the towers. Here's an article explaining the technicals of it: http://blog.3g4g.co.uk/2010/10/fast-dormancy-in-release-8.ht...
Easier read: http://www.3glteinfo.com/fast-dormancy-in-3gpp/
Would agree though that process size and baseband optimization is helping the LTE situation. Differences are very small and Apple actually quotes better LTE life on the SE than 3G. LTE really came into its own in just the past 2 years.