| Applicable Versions | NetSim Standard | NetSim Pro |
| Applicable Releases | v13.2 |
The scheduling algorithms will have a significant impact on the throughput experienced by the UE's when the UE's are placed at different distances (different CQI/MCS) from the gNBs.
NetSim supports the following Scheduling Algorithms:
1. Round Robin
2. Proportional Fair
3. Max Throughput
The Scheduling mechanism can be selected from gNB Properties > Interface 5G RAN > Datalink Layer
At each gNB the MAC scheduler decides the PRB allocation, in each slot (TTI), for DL and UL, for each carrier. Control packets such as the buffer status report (BSR) and UL assignment, are assumed to be sent out of band. The MAC scheduler works as follows:
- Round Robin: It divides the available PRBs among the active flows, i.e., those logical channels which have a non-empty RLC queue. The MCS for each user is calculated according to the received CQIs.
- Proportional fair: The Proportional Fair (PF) scheduler works by scheduling a user when its instantaneous channel quality is high relative to its own average channel condition over time. The PF scheme is based on information such as a presently available data rate for each user and an average data rate over an immediately prior predetermined interval for each user. In comparison with the round-robin (RR) scheduler in which UEs are cyclically scheduled irrespective of the channel condition, the PF scheduler maximizes the system throughput while maintaining long-term fairness in the allocation of resources between users.
- Max throughput: It allocates PRBs to the active flow(s) to maximize the achievable rate. In other words, it selects the user that sees the highest CQI.
Note that these are MAC scheduling algorithms, and do not use the QoS parameter that can be set in the Application properties in NetSim’s GUI
Useful links
1. Documentation: https://tetcos.com/help/v13.2/Technology-Libraries/5G.html#mac_scheduler_introduction
2. Examples on MAC scheduler: https://tetcos.com/help/v13.2/Featured-Examples/5G/Impact-of-MAC-Scheduling-algorithms-on-throughput-in-a-Multi-UE-scenario.html