LTE / LTE-Advanced
3GPP TS 36-series · EPC · eNodeB · UE
NetSim's LTE model library is a high-fidelity, packet-level simulation of 4G and 4.5G cellular networks built to the 3GPP TS 36-series. It models the EPC, eNodeB, and UE with a full RRC-to-PHY stack, MIMO, HARQ, link adaptation, carrier aggregation, and handover. Every protocol ships as source in C.
What NetSim models
A complete LTE network, from the EPC down to the radio interface, with the standards-based detail needed to study capacity, scheduling, link adaptation, and end-to-end performance.
Radio access
An eNodeB serving UEs over an OFDMA downlink and SC-FDMA uplink, with QPSK to 64QAM, FDD, and MIMO transmission modes TM1 to TM5.
Full protocol stack
RRC, PDCP, RLC, MAC scheduling, and PHY implemented to the 3GPP 36-series, over IPv4, TCP and UDP transport, and standard application traffic.
EPC and IP core
An Evolved Packet Core that bundles the MME, SGW, and PGW, giving end-to-end IP connectivity from the UE through the eNodeB to routers, switches, and servers.
Own the source
Every protocol ships as C source. Modify it in Visual Studio to implement and test your own scheduling, link adaptation, or PHY ideas.
Devices
Three LTE-specific nodes drop into the topology and connect to the standard NetSim devices.
EPC
The Evolved Packet Core is the equivalent of the MME in LTE and bundles the PGW, SGW, and MME. It provides end-to-end IP connectivity and connects to routers, switches, access points, and servers in the core.
Macro cell eNB
The Evolved NodeB is the LTE base station. Every eNB serves at least one UE and can be placed inside buildings to study indoor and outdoor coverage.
UE
User Equipment, always associated with exactly one eNB. Move UEs with mobility models to study how the link and the scheduler respond.
Alongside standard NetSim routers, L2 / L3 switches, access points, and wired and wireless nodes.
The LTE protocol stack
Control and user plane from RRC down to MAC scheduling, each implemented to its 3GPP specification and open in source.
Control plane
- System information: MIB and SIB1 acquisition
- RRC connection establishment
- RRC Idle, Connected / Active, and Inactive states
Convergence
- Sequence numbering and PDCP association
- ROHC robust header compression
- Discard timer and duplicate discard
Radio link control
- Transparent Mode (TM)
- Unacknowledged Mode (UM)
- Acknowledged Mode (AM) with retransmission
Scheduling
- Round Robin
- Proportional Fair
- Max Throughput
PRBs allocated per slot per carrier; MCS from reported CQI.
Physical layer
Standard 3GPP TS 36.213. The air interface is configurable across bandwidths, transmission modes, and antenna configurations.
Transmission modes
SISO
A single antenna at the eNodeB. With round-robin scheduling all flows see equal throughput.
Transmit diversity
MIMO transmit diversity (TxD) sends copies of the same data over multiple antennas for higher reliability at the same throughput.
Open-loop SU-MIMO
Single-user spatial multiplexing, open loop. Data is split across antennas to raise the data rate.
MU-MIMO
Multi-user spatial multiplexing per the LTE standard, raising throughput across multiple users.
MU-MIMO (2 Rx)
Multi-user MIMO with the number of receive antennas fixed at two.
Resource block
12 subcarriers of 15 kHz over 0.5 ms (7 OFDMA symbols). Modulation QPSK (2 bits), 16QAM (4), and 64QAM (6).
| Channel bandwidth (MHz) | 1.4 | 3 | 5 | 10 | 15 | 20 |
|---|---|---|---|---|---|---|
| Resource blocks (NRB) | 6 | 15 | 25 | 50 | 75 | 100 |
| Occupied subcarriers | 73 | 181 | 301 | 601 | 901 | 1201 |
| FFT size | 128 | 256 | 512 | 1024 | 1536 | 2048 |
| Sampling rate (MHz) | 1.92 | 3.84 | 7.68 | 15.36 | 23.04 | 30.72 |
| Downlink / uplink access | OFDMA / SC-FDMA |
|---|---|
| Duplexing | FDD (carrier aggregation also supports TDD) |
| Subcarrier spacing | 15 kHz |
| Frame / subframe / slot | 10 ms / 1 ms / 0.5 ms |
| Operating bands | 3GPP TS 36.101 LTE / LTE-A bands |
| Modulation | QPSK, 16QAM, 64QAM |
Link adaptation and error modelling
How NetSim chooses a modulation and coding scheme, models block errors, and recovers from them, the engine behind realistic LTE throughput.
HARQ
Hybrid ARQ in MAC and PHY, in downlink and uplink, with up to 8 processes per direction per component carrier. Chase combining stores and combines failed transmissions.
BLER and MCS selection
Zero-BLER mode picks the MCS from an ideal Shannon or attenuation-factor rate (TR 36.942). BLER-enable mode transmits with errors from NetSim's BLER-MCS-SINR curves.
OLLA and AMC
Outer-loop link adaptation tunes the MCS toward a target BLER using HARQ ACK / NACK feedback. AMC works from a wideband SNR averaged over a configurable window.
Code block segmentation
Each transport block is split into code blocks grouped into code block groups (CBGs) for selective retransmission, with CBGs retransmitted at the original MCS.
Spectrum, interference, and propagation
Aggregate carriers for more bandwidth, model intercell interference, and drive the link with standards-based propagation.
Carrier aggregation
Aggregate up to five component carriers of 1.4 to 20 MHz, for up to 100 MHz. Intra-band contiguous and non-contiguous, and inter-band non-contiguous, over FDD and TDD.
Downlink interference
No-interference by default, or a graded distance-based Wyner model that accounts for interference from any number of base stations and the UE's location.
Propagation models
3GPP TR 38.901 path loss across rural macro, urban macro, urban micro, and indoor office, with LOS / NLOS, outdoor-to-indoor loss, log-normal shadow fading, and Rayleigh fading.
Network, transport, applications, and mobility
The LTE radio sits under a full IP stack, so you can drive it with realistic traffic, routing, movement, and handover.
Network layer
IPv4 across the core, with RIP and OSPF routing in the EPC and core network.
Transport layer
TCP with Old Tahoe, Tahoe, Reno, New Reno, and BIC CUBIC variants, plus UDP.
Application layer
HTTP, CBR, email, video, voice, FTP, and other application traffic models.
Mobility and handover
Random walk, random waypoint, group, and file-based mobility, with eNB-to-eNB handover driven by serving and target SNR and a time-to-trigger.
Metrics and logs
Summary statistics for quick answers and detailed per-event logs for deep analysis of the radio link.
Network and LTE metrics
Network-wide statistics alongside LTE cell metrics, including PDSCH and PUSCH throughput per eNB interface.
IP, TCP / UDP, application
IP metrics, TCP and UDP transport metrics, and per-application performance statistics.
Dynamic metrics
Time-series plots of an attribute, including application throughput and individual link throughput, plus the LTE packet trace.
Radio measurements log
Per-slot SNR, received power, path loss, and the CQI / MCS used on the link.
Radio resource allocation log
PRB allocation per slot and carrier, with the scheduler's per-UE decisions.
Handover log
Time, UE, serving and target cell, serving and target SSB SNR, and time-to-trigger remarks.
Code block log
Process ID, TB size, modulation, code rate, code block size, BLER, and CBG ID per transmission.
OLLA log
CQI with and without OLLA, PHY SINR, SINR delta, and virtual SINR per carrier and layer.
Packet and event traces
Per-packet and per-event records across the network for end-to-end debugging.
Next generation
From LTE to 5G NR
LTE is the 4G baseline, and NetSim builds it on the same engine as 5G NR. When you are ready to model 5G, the NR library adds the new radio: flexible numerology, mmWave (FR2), massive MIMO and beamforming, 16 HARQ processes, and network slicing, over the same workflow and C source model.
- Flexible numerology and wide bandwidths
- FR1 and FR2 (mmWave)
- Massive MIMO and beamforming
- Network slicing and AI/ML in the RAN
Useful links
Documentation, the knowledge base, file exchange, and support to take an LTE project further.