# Dynamic Packet Duplication for Industrial URLLC
## 4 Tests
### Simulation Scenario  
The scenario consists in an indoor factory, with an area of 4800 m\({}^{2}\) and a height of 10 meters. The scenario is based on the one proposed in 3 GPP 38.901 (Table 7.8-7) [38], which was used to calibrate the indoor factory scenario defined in Release 16. In particular, the Indoor Factory with Dense clutter and High base station (InF-DH) [38] scenario was selected with a clutter height of 6 m and clutter density of 80%.  
Attending to the RAN part, there are two picocells with a height of 8 m, which are interconnected via Xn interface, with a base station distance of 50 m. Both gNBs operate with a frequency of 3.7 GHz and a bandwidth of 20 MHz. One transmission/reception omnidirectional antenna was used in both, picocells and UEs, with 23 dBm as downlink transmission power. Figure 4 shows the distribution of the scenario simulated.  
The slot length configured is set to 0.25 ms, which corresponds to numerology 2, as defined in the standard [39]; whereas the number of HARQ retransmissions attempts was set to a maximum of 1, due to URLLC latency constraints. Moreover, the link adaptation used at gNB for MCS selection is an error model-based, where the MCS is selected to meet a target transport Block Error Rate (BLER). The MCS table used is Table 1 (up to 64-QAM) from 3 GPP 38.214 [40]. The delay for the scheduling procedure was set as following:  
* The packet processing from MAC to PHY layer is fixed at two slots. This is a delay between the control/data acquisition from the RLC layer by the MAC layer and the moment at which the data is available to go over the air.  
* The transport block decode latency is set to 100 microseconds at UE and gNB. It is a delay between the data acquisition from the air by the PHY layer and the moment at which the data block is available to process at the MAC layer.
* The processing delay needed to decode Downlink Control Information (DCI) and decode downlink data is set to 0 slots.
* The processing delay needed from the end of downlink data reception to the earliest possible start of the corresponding ACK/NACK transmission is set to 1 slot.  
On each base station, there are 15 UEs attached, whose positions are fixed and randomly selected at the beginning of the simulation. For each UE, a Constant Bit Rate (CBR) flow of 1 Mbps is sent by the gNB in downlink direction.  
On the other hand, there is a URLLC device that is connected to both gNBs simultaneously, one acting as a MN and the other one as a SN. The initial position of the URLLC device is random over the scenario, using a uniform distribution. Then, when the simulation begins, the URLLC device selects a random direction (where all angles are equiprobable, since a uniform distribution is used) over 360 degrees and maintains that direction during 10 s with a speed of 2 m/s.  
When the timer expires, a new direction is selected. The URLLC device represents an AGV that is remotely controlled by the network. To do this, the network sends short commands, in this case, UDP packets with a periodicity of 10 ms and size of 64 bytes.  
In this paper, a MEC [20] is considered to allocate the URLLC service at the network edge. Thus, the main contribution of the latency comes from the RAN. Table 1 shows the main configuration parameters of the simulations.