5G Core Slice Dimensioning
Configure each network slice to dimension UPF, SMF, and AMF capacity requirements for 5G SA.
Total SIMs or IoT devices on this slice
% simultaneously active in busy hour
Sustained data rate per active subscriber
Used to compute UPF packet rate
Concurrent sessions per device
SMF N11 signaling driver
AMF NG-AP / N8 signaling driver
eMBB slice results
Total SIMs or IoT devices on this slice
% simultaneously active in busy hour
Sustained data rate per active subscriber
Used to compute UPF packet rate
Concurrent sessions per device
SMF N11 signaling driver
AMF NG-AP / N8 signaling driver
URLLC slice results
Total SIMs or IoT devices on this slice
% simultaneously active in busy hour
Sustained data rate per active subscriber
Used to compute UPF packet rate
Concurrent sessions per device
SMF N11 signaling driver
AMF NG-AP / N8 signaling driver
mIoT slice results
Total UPF throughput
7660.0 Gbps
Total UPF packet rate
775.89 Mpps
Total simultaneous sessions
2,600,000
Total SMF session rate
694.44 sessions/s
Total AMF registration rate
194.444 reg/s
5G Network Slice Reference
S-NSSAI structure (3GPP TS 23.003)
S-NSSAI = SST (8 bits) + SD (24 bits, optional)
SST — Slice/Service Type: identifies the slice category
SD — Slice Differentiator: distinguishes multiple slices of the same SST
Example: SST=1, SD=0x000001 → eMBB slice instance 1 for a specific tenant.
Standardised SST values (3GPP TS 23.501)
| SST | Slice type | Typical use case |
|---|---|---|
| 0 | Reserved | Not used |
| 1 | eMBB — enhanced Mobile Broadband | Smartphones, FWA, video streaming, 4K/8K media |
| 2 | URLLC — Ultra-Reliable Low-Latency | Industrial automation, remote surgery, V2X, smart grid |
| 3 | mIoT — massive IoT | Smart meters, sensors, asset tracking, NB-IoT/LTE-M |
NF dimensioning guidelines
| Network Function | Primary metric | Dominant slice | Typical range |
|---|---|---|---|
| UPF | Throughput (Gbps) + pps | eMBB (throughput), URLLC/mIoT (pps) | 10–100 Gbps / instance |
| SMF | Session setup rate (sessions/s) | URLLC (high churn), mIoT (volume) | 1,000–10,000 sessions/s |
| AMF | Registration rate (reg/s) | mIoT (device count), URLLC (mobility) | 500–5,000 reg/s |
| PCF | Policy decisions/s (N7 interface) | eMBB (QoS), URLLC (strict SLA) | Proportional to SMF rate |
Frequently Asked Questions
What is 5G network slicing?▾
Network slicing is a 5G SA (Standalone) feature that allows a single physical network to be partitioned into multiple logical networks, each with its own QoS, isolation, and NF configuration. Each slice is identified by an S-NSSAI (Single Network Slice Selection Assistance Information) consisting of an SST (Slice/Service Type: 1=eMBB, 2=URLLC, 3=mIoT, 4=V2X) and an optional SD (Slice Differentiator). Slices are selected by the AMF and SMF during PDU session establishment and enforced by the UPF.
What is UPF and how is its capacity dimensioned?▾
The UPF (User Plane Function) is the gateway between the 5G RAN and the data network (internet or enterprise). UPF capacity is measured in throughput (Gbps) for sustained data flows and packets per second (pps) for burst traffic. eMBB slices drive throughput requirements; URLLC and mIoT slices can drive high pps requirements due to small, frequent packets. A single UPF instance typically handles 10–100 Gbps depending on vendor; horizontal scaling via multiple UPF instances is standard in 5G SA.
What is the role of SMF in slice dimensioning?▾
The SMF (Session Management Function) handles PDU session establishment, modification, and release for each slice. It programs the UPF via the N4 interface (PFCP protocol) and interfaces with the PCF for policy. SMF is dimensioned by session setup rate (sessions/second) and the total number of simultaneous active sessions. URLLC slices with frequent short sessions and mIoT slices with millions of low-data-rate devices can generate high SMF signaling load even at low throughput.
How does mIoT slicing differ from eMBB?▾
mIoT (massive IoT) slices serve large numbers of devices (millions) that each generate very low throughput (kilobits per second) but may transmit infrequently. The UPF throughput demand is low, but the AMF and SMF face high signaling load from device registration, periodic tracking area updates, and session setup/teardown at scale. Power-saving features like eDRX (extended DRX) and PSM (Power Saving Mode) are configured per slice to reduce AMF paging load from IoT devices.