nru.py is a discrete-event simulator of channel access for NR-U base stations (gNBs) written in Python using the SimPy library. The simulator implements the listen before talk (LBT) competitive channel access mechanism under the assumption that NR-U transmissions may begin only at slot boundaries. The simulator supports any number of transmitting stations and configurable transmission parameters. It outputs the following metrics:
- collision probability -- ratio between collided and all attempted transmissions,
- channel efficiency -- ratio of successful transmission duration and simulation time,
- Jain's fairness index -- calculated over per-station airtime.
Simply run nru.py in a Python environment.
The following parameters set in the script may be of particular interest:
SYNCHRONIZATION_SLOT_DURATION = 1000 # synchronization slot duration [us]
RS_SIGNALS = False # if True use reservation signals else gap
PARTIAL_ENDING_SUBFRAMES = False # if True, random last slot duration (1-14 OFDM symbols)
[...]
CW_MIN = 15 # minimum contention window value
CW_MAX = 63 # maximum contention window value
[...]
SIM_TIME = 100 # simulation time
SEED = 42 # seed for PRNG
NR_OF_GNBS = 10 # number of transmitting gNBsThe simulator was used to conduct the research presented in the following papers:
- M. Zając and S. Szott, "Resolving 5G NR-U Contention for Gap-Based Channel Access in Shared Sub-7 GHz Bands," in IEEE Access, vol. 10, pp. 4031-4047, 2022, doi: 10.1109/ACCESS.2022.3141193.