Air Carrier Captain reported the AUS ramp area is subject to frequent ground conflicts; in large part because the ramp is not controlled by ATC.

Narrative

After landing on 18R Tower instructed us to taxi to the Gate via Taxiways C; C1 to Gate XX. Once we turned the corner to R4 to proceed to the gate we noticed Aircraft X that was off their gate blocking our path to our gate. The ramp is uncontrolled and they were not communicating when we inquired ATC about whether they were parking or exiting. ATC informed us ramp was uncontrolled and not coordinating ramp traffic. R4 had a blocked off area with construction cones. Aircraft were parked at Gates XY and XZ limiting our options to maneuver. ATC gave us a frequency not in our publications to try to communicate with Aircraft X. We heard Aircraft X communicate on ground frequency that they needed to exit. We had to make a left u turn from R5 onto C1 (thankfully we were not further in the alley otherwise the construction cones would have prohibited a turnaround).An aircraft was coming up Taxiway C so we chose to taxi eastbound on C2. We asked ATC if we could exit G3 and taxi G back to C and C1 to the gate. ATC said they had an aircraft about to taxi up from G3. So we looked for clear area to make another u turn on C1 from C2. Aircraft X was able to exit R4 and once clear we proceeded to the gate without incident. Captain spoke with ATC over the phone about the ramp congestion and lack of aircraft coordination on the ramp. He stated this is a known issue with the amount of traffic now operating in and out of AUS but the city has yet to give control of the ramp to ATC. With the combination of aircraft either parked on R5 and/or construction and the proximity of parked aircraft on the gates mainly at the west terminal along with no ramp control or coordination this presents a safety issue (especially at night) when aircraft have to make u turns to clear a path for aircraft exiting the alley on the west terminal. This can also lead to a jamming up of the ramp area delaying flights as they try to coordinate amongst themselves a taxi plan. It is simply too busy an airport to leave ramp uncontrolled.