  One of the main novelties in 5G is the flexible Time Division Duplex (TDD)
frame, which allows adaptation to the latency requirements. However, this
flexibility is not sufficient to support heterogeneous latency requirements, in
which different traffic instances have different switching requirements between
Uplink (UL) and Downlink (DL). This is visible in a traffic mix of enhanced
mobile broadband (eMBB) and ultra-reliable low-latency communications (URLLC).
In this paper we address this problem through the use of a decoupled UL/DL
access, where the UL and the DL of a device are not necessarily served by the
same base station. The latency gain over coupled access is quantified in the
form of queueing sojourn time in a Rayleigh channel, as well as an upper bound
for critical traffic.
