Question: In E-UTRA, for PUCCH format 3, what is the number of encoded ACK/NACK (AN) bits per sub-frame specifically applicable to TDD scenarios where higher reliability is required?
Option 1: 2 AN bits, regardless of duplex mode
Option 2: 4 AN bits, common for both FDD and TDD
Option 3: 16 AN bits, specifically for enhanced TDD reliability
Option 4: 8 AN bits, a compromise between FDD and high-reliability TDD
Explanation: In E-UTRA, for PUCCH format 3, the specification distinguishes between the number of encoded ACK/NACK bits per sub-frame based on the duplex mode. While both FDD and a basic TDD scenario use 4 AN bits, a higher reliability scenario specifically for TDD employs more robust signaling, hence utilizing **16 AN bits** to ensure more dependable transmission and reception of ACK/NACK feedback, crucial for maintaining efficient and reliable communication in TDD modes where uplink and downlink share the same frequency band.