Power Monitoring for Energy Efficient 5G/6G with OAI and USRP

Application Note Number and Authors

AN-844

Authors

Bharat Agarwal and Neel Pandeya

Executive Summary

Energy efficiency is becoming a critical KPI for 5G-Advanced and 6G systems, especially in Open RAN, AI-driven PHY, and Integrated Sensing and Communication (ISAC) testbeds.

Real-time power monitoring enables:

• Evaluation of baseband processing efficiency
• Measurement of RF front-end power consumption
• AI accelerator energy profiling
• Optimization of system-level energy-per-bit metrics

This application note demonstrates how to implement accurate power monitoring in a 5G/6G testbed using NI measurement hardware and software tools.

Demonstrator Scope and Overview

This demonstrator implements a measurement framework to synchronously monitor and measure power and energy consumption across multiple heterogeneous components of a wireless system.

Syncronized Power Monitoring for Wireless systems using Open-Air-Interface with NI USRP and NI cRIO (*Note: For the demo, the base station prototype is connected to a 5G prototype user terminal which is not shown on the block diagram.) ​

Device Under Test (DUT)

5G/6G Base Station Prototype, consisting of:

• Linux server (baseband processing platform)
• OpenAirInterface (OAI) base station stack
• NI USRP (RF front-end)
• External switchable power amplifier (PA)

1. 3GPP-Aligned Demo Use Case

Energy Savings via Enhanced Cell Sleep Mechanisms

• Demonstrates energy reduction at the base station power amplifier.
• Evaluates increased cell sleep opportunities.
• Quantifies real-time power savings during inactive traffic periods.

2. AI-RAN Demo Use Case

Energy Profiling of AI-Native vs. Traditional Receiver

• Measures energy consumption of:
  • AI-native base station receiver
  • Traditional (e.g., LMMSE-based) receiver

Key Feature of the Measurement Framework

All power and energy measurements are:

• Fully synchronized to a common time grid
• Aligned with the 500 µs slot grid of the 5G NR system

This synchronization enables:

• Slot-level energy analysis
• Accurate correlation between radio activity and power consumption
• Fine-grained energy profiling of PHY processing, RF transmission, and AI inference workloads

Demonstrator System Architecture

The diagram presents a Demonstrator System Architecture used for power‑aware testing of a 5G/6G Base Station Prototype (gNB) and NI USRP. ​

1. 5G/6G Base Station Prototype (gNB)

The DUT includes power sensors (GPU, CPU), a power supply, and an open-source 5G/6G stack from OpenAirInterface. It connects to NI USRP hardware and an external power amplifier. Power channels (AC/DC) are monitored for measurement.

2. NI CompactRIO Power Measurement System

• cRIO Controller 9047 for power calculation and data aggregation
• Measurement modules:
  • NI-9244 — AC voltage (400 Vrms)
  • NI-9238 — AC current (±500 mV)
  • NI-9229 — DC voltage (±60 V)
  • NI-9227 — DC current (5 Arms)
• Collects voltage and current measurements from gNB components

3. NI Data Recording Entity / Server

This Linux server handles:

• System configuration
• Test execution
• Data recording
• Data visualization

All measurement data is stored in a data lake with timestamps and metadata.

4. 5G User Terminal (UE)

The UE runs an open-source 5G stack from OpenAirInterface and communicates with the gNB via NI USRP hardware over a wired or wireless RF channel.

Overall Workflow

The gNB and UE communicate over RF. The CompactRIO system measures power data from the gNB and sends it to the centralized data server for recording and analysis.

Demonstrator Setup

The image shows a real‑world hardware setup corresponding to the demonstrator architecture. The numbered labels in the picture match three major system components. ​

1. Device Under Test (DUT): 5G Base Station

The left side of the setup contains the 5G base station prototype with an external switchable power amplifier. A computing platform equipped with an NVIDIA RTX 4090 GPU runs the 5G gNB software stack. Multiple cables connect the DUT to measurement equipment and RF interfaces.

2. NI cRIO Power Measurement System

The central upper part of the setup features the NI cRIO system with an attached breakout box for sensor connections. This equipment measures voltage, current, and power consumption from the DUT and forwards the data to the recording server.

3. Data Recording Entity

The central lower section includes the NI Data Recording Entity, responsible for data orchestration, logging, aggregation, and visualization. A monitor above shows dashboards and measurement results.

5G User Terminal (UE)

On the right side is the 5G User Terminal (UE), which acts as the RF counterpart to the DUT. It connects through RF interfaces for 5G communication testing.

5G Sub‑System Demo Configuration (gNB + UE)

1. Wireless Scenario

• Single link between one gNB and one UE
• Wired RF connection
• No interference from:
  • Neighboring cells
  • Other UEs

Operating Band

• NR Band: n78

Waveform & Numerology

• Subcarrier Spacing (SCS): 30 kHz
• Waveform: CP‑OFDM
• Channel Bandwidth: 40 MHz
• Maximum PRBs: 106

3. Downlink (DL) Scheduling

• Scheduled DL PRBs:
  • 20 PRBs
  • 80 PRBs
• Switch interval: Every 10 frames

4. Uplink (UL) Scheduling

• Scheduled UL PRBs: 6 (kept low to ensure gNB Neural Rx real‑time performance)
• UL transmission bandwidth: ~2.16 MHz

5. TDD Configuration

DL/UL periodicity: 5 ms

TDD Slot & Symbol Structure

Parameter	Value
nrofDownlinkSlots	7
nrofDownlinkSymbols	6
nrofUplinkSlots	2
nrofUplinkSymbols	4

6. PUSCH Configuration

• Mapping type: B
• PUSCH duration: 13 OFDM symbols
• DMRS configuration:
  • Type 1
  • dmrs-AdditionalPosition = pos2
  • DMRS positions: Symbols 0, 5, 11

Hardware System Block Diagram Explanation

The diagram shows a full hardware setup for a 5G/6G research testbed. ​

1. OAI Base Station (gNB) – Linux Server 1

This server runs the OpenAirInterface gNB software stack. It includes an NVIDIA RTX 4000 GPU and connects to a USRP X410 via high-bandwidth 4×25 GbE (QSFP28 to 4×SFP28). RF paths pass through 20 dB attenuators and HDMI breakout connectors.

2. OAI Soft User Terminal (UE) – Linux Server 2

This subsystem runs the OAI software UE. It connects to another USRP X410 using dual-port 25 GbE NICs and the same 4×25 GbE optical links.

3. USRP X410 Radios

Two USRP X410 SDR units are used—one for the gNB and one for the UE. They interface via optical fiber and RF lines routed through attenuation and power amplification modules.

4. Data Recording – Linux Server 3

This server includes quad-port 10 GbE NICs and 10/25 GbE SFP28 links for capturing IQ, logs, and network traffic. USB-A to USB-C serial connections provide PA control. It exchanges control and logging data via 1GE Ethernet.

5. Fast Switching Power Amplifier

A Skyworks SKY67154 fast-switching PA is shown between RF attenuation blocks. It provides controlled RF gain for more realistic testing scenarios.

6. RF Attenuators and Breakout Hardware

The RF path includes multiple fixed 20 dB attenuators and adjustable 15–20 dB attenuators. HDMI breakout connectors are used for additional RF signal routing and measurement.

7. High-Speed NICs and Optical Links

The system uses QSFP28 to 4×SFP28 breakout cables, 10/25 GbE NICs, and quad-port NICs to transport high-rate IQ and control messages between servers and USRPs.

Power Monitoring Demonstrator – Materials Summary

The Power Monitoring Demonstrator integrates high‑performance servers, SDR radios, RF components, and NI measurement hardware to evaluate and monitor the power consumed during wireless 5G/6G operation. Servers provide compute and networking, USRPs generate and receive RF signals, and the cRIO system captures accurate AC/DC measurements. RF attenuators, cables, and accessories ensure safe and controlled signal flow during operation.

Equipment	Type	Quantity
Server	Dell Precision 5860 Tower	3
Network Card (10GbE SFP+)	Intel X710 Quad Port 10GbE SFP+ Adapter	1
Eth Cable (SFP+)	10G Eth Cable SFP+ 2m	2
SFP-to-RJ45 Adapter	SFP 1 Gigabit Ethernet Interface Kit / FCLF8522P2BTL	1
Network Card (25GbE SFP28)	Mellanox NIC 2×1/10/25GbE SFP28 (MCX512A-ACAT)	4
QSFP28 → 4×SFP28 Cable	NVIDIA MCP7F00-A003R26N 100GbE to 4×25GbE, 3m or NI QSFP28→4×SFP28 Breakout (PN 788214-01)	2
NVIDIA GPU	NVIDIA GeForce RTX 4090 Founders Edition	1
Extra GPU Power Cable	COMeap 10‑pin to 8‑pin PCIe Cable (not required for Dell 5860)	1
NI USRP	USRP X410	2
External Clock + PPS Source	OctoClock‑G CDA‑2990	1
cRIO Power Measurement System	cRIO 9047 + NI 9238, NI‑9244, NI‑9229, NI‑9227 modules	1
RF Cables	SMA(M)‑to‑SMA(M) RF Cables (1m)	7
20 dB RF Attenuators	SMA‑F to SMA‑M Attenuators	2
10 dB RF Attenuators	SMA‑F to SMA‑M Attenuators	2
Switchable Power Amplifier	Skyworks PA SKY67154	1
AC Current Clamps	Magnelab SCT‑0750‑020	2
HDMI Breakout Connector	19‑pin HDMI Terminal Block Adapter	1
USB‑C to USB‑A Cable	Standard	1
Network Switch (Optional)	4+ Ethernet Ports (for demo / remote access)	1
1G Ethernet Cables	Standard	4

RF and Network Connections Overview

The diagram shows a RF and Network Connections Overview. ​

System Overview

This testbed implements a complete 5G NR gNB ↔ UE link in a wired back-to-back configuration using Open Air Interface (OAI) software. Three Linux servers handle baseband processing, user terminal emulation, and data recording respectively. Two USRP X410 units serve as the RF front-ends, connected through attenuators and a fast-switching power amplifier.

Hardware Components

Linux Server 1 - OAI Base Station

• Runs the OAI gNB 5G NR stack
• Equipped with Nvidia RTX 4090 GPU for real-time baseband acceleration (LDPC, FFT, channel estimation)
• Connected to USRP X410 via 4×25GbE QSFP28 → 4×SFP28 breakout cable
• Controls the Fast Switching PA via HDMI breakout connector + GPIO wires

Linux Server 2 - OAI Soft User Terminal (UE)

• Runs the OAI UE software stack (soft user terminal)
• Mirror configuration to Server 1
• Connected to USRP X410 via 4×25GbE QSFP28 → 4×SFP28 breakout cable

Linux Server 3 — Data Recording

• Central logging, packet capture, and experiment orchestration server
• Connects to both Server 1 and Server 2 via 10/25GbE SFP28 or 10GbE SFP+
• Connects to auxiliary small chassis via 1GbE and USB-A → USB-C serial

USRP X410 (×2)

• NI/Ettus Software Defined Radio units acting as the RF front-end
• One unit per server (gNB side and UE side)
• I/Q samples streamed over high-speed SFP28 links

Fast Switching PA — Skyworks SKY67154

• Wideband GaAs power amplifier on a custom breakout PCB
• GPIO-controlled via HDMI breakout from Server 1
• Enables TDD-synchronized TX/RX switching aligned to 5G NR slot timing

Attenuators

Position	Value	Purpose
gNB TX output	20 dB	Prevent USRP X410 TX overdrive
PA output (DL)	15–20 dB	Protect UE-side USRP RX input
UE TX output (UL)	20 dB	Protect gNB-side USRP RX input

NI cRIO (CompactRIO)

Connected to Server 3 via 1GbE (192.168.120.2) and USB-C serial console. The NI cRIO acts as a real-time embedded controller used for low-latency hardware control, timing synchronization, and auxiliary I/O management within the testbed.

Network Interfaces

Server 1 ↔ Server 3 (Management / Data)

Parameter	Value
Server 1 IP	192.168.100.2
Server 3 IP	192.168.100.1
Link Type	10/25GbE SFP28 or 10GbE SFP+

Server 2 ↔ Server 3 (Management / Data)

Parameter	Value
Server 2 IP	192.168.110.2
Server 3 IP	192.168.110.1
Link Type	10/25GbE SFP28 or 10GbE SFP+

Server 1 ↔ USRP X410 (Fronthaul)

Parameter	Value
Server 1 IPs	192.168.10.2 / 192.168.11.2
USRP X410 IPs	192.168.10.1 / 192.168.11.1
Link Type	4×25GbE QSFP28 → 4×SFP28

Server 2 ↔ USRP X410 (Fronthaul)

Parameter	Value
Server 2 IPs	192.168.10.2 / 192.168.11.2
USRP X410 IPs	192.168.10.1 / 192.168.11.1
Link Type	4×25GbE QSFP28 → 4×SFP28

Server 3 ↔ NI cRIO

Parameter	Value
Server 3 IP	192.168.120.1
NI cRIO IP	192.168.120.2
Link Type	1GbE + USB-A → USB-C Serial

RF Signal Chain

Downlink (gNB TX → UE RX)

USRP X410 (Server 1)
    │
    ▼
20 dB Attenuator
    │
    ▼
Fast Switching PA (Skyworks SKY67154)
    │
    ▼
15–20 dB Attenuator
    │
    ▼
USRP X410 (Server 2)

Uplink (UE TX → gNB RX)

USRP X410 (Server 2)
    │
    ▼
20 dB Attenuator
    │
    ▼
USRP X410 (Server 1)

Note: The Fast Switching PA is only in the downlink path. The HDMI breakout connector carries GPIO control signals from Server 1 to enable time-synchronized PA switching per 5G TDD frame structure.

IP Address Reference

Device	Interface	IP Address
Server 1	To Server 3	192.168.100.2
Server 1	To USRP P1	192.168.10.2
Server 1	To USRP P2	192.168.11.2
Server 2	To Server 3	192.168.110.2
Server 2	To USRP P1	192.168.10.2
Server 2	To USRP P2	192.168.11.2
Server 3	To Server 1	192.168.100.1
Server 3	To Server 2	192.168.110.1
Server 3	To NI cRIO	192.168.120.1
USRP X410 (gNB)	P1	192.168.10.1
USRP X410 (gNB)	P2	192.168.11.1
USRP X410 (UE)	P1	192.168.10.1
USRP X410 (UE)	P2	192.168.11.1
NI cRIO	To Server 3	192.168.120.2

Power Measurement and PA Control Connections

The diagram shows the Power Measurement and PA Control Connections. ​

Power Measurement & PA Control Connections

This section describes the power measurement setup and PA control wiring used in the 5G NR testbed, including DC/AC measurement modules installed in the NI cRIO chassis and the PA enable signal from the USRP X410.

System Components

Component	Description
Base Station Server	Main compute server running the OAI gNB stack
RU (USRP X410)	Radio Unit providing RF front-end and PA enable GPIO via HDMI breakout
Fast Switching PA Fixture	Skyworks SKY67154 PA board receiving V_EN control signal and DC supply
NI cRIO Chassis	CompactRIO hosting measurement modules for DC and AC power monitoring
Main Power Supply	AC mains supply powering the gNB and RU equipment
cRIO DC Supply	24V / 5A dedicated DC supply for the NI cRIO chassis
5V USB Power Supply	5V supply for the Fast Switching PA Fixture (V_DD)

NI cRIO Measurement Modules

Module	Type	Channel	Wiring
NI 9227	DC PA Current	Ch0	According to current flow: 0+ to 0−
NI 9229	DC PA Voltage	Ch0	red − 0+ / black − 0−
NI 9238	AC Current	gNB − ch0 / RU − ch1	White − 0+ / Black − 0−
NI 9244	AC Voltage	L1, N	AC Voltage measurement

PA Enable Control (HDMI Breakout)

The USRP X410 (RU) controls the Fast Switching PA via the HDMI breakout connector. The GPIO pins carry the PA enable signal synchronized to the 5G TDD frame timing.

HDMI Pin	Signal	Wire Color	Description
Pin 17	GND	Black	Ground reference
Pin 16	V_EN	Red	3.3V PA enable signal

Note: The signal is labeled GPIB HDMI PA enable in the diagram. The V_EN line switches the PA on/off in sync with gNB TX/RX slot timing.

Power Supply Connections

Supply	Voltage / Current	Powers	Connection
Main Power Supply	AC Mains	Base Station Server + RU (USRP X410)	To AC Power Supply (×2 outputs)
cRIO DC Supply	24V / 5A	NI cRIO Chassis	Direct DC wiring to cRIO
5V USB Power Supply	5V	Fast Switching PA Fixture (V_DD)	Red (+) / Black (−) wiring to PA board

AC Power & Measurement Wiring

AC power is distributed from the Main Power Supply via a green wire bus to:

• The NI cRIO chassis (via NI 9244 AC Voltage module — L1, N)
• The NI 9238 AC Current module measuring current drawn by gNB (ch0) and RU (ch1)

The cRIO ground and AC Current sense lines are connected at the cRIO chassis as indicated by the blue arrow in the diagram.

Signal Flow Summary

AC Mains
    │
    ├──► Main Power Supply ──► Base Station Server
    │                     └──► RU (USRP X410)
    │
    ├──► NI 9244 (AC Voltage: L1, N)
    ├──► NI 9238 (AC Current: gNB ch0, RU ch1)
    │
    └──► cRIO DC Supply (24V/5A) ──► NI cRIO Chassis

RU (USRP X410)
    │
    └──► HDMI Breakout (Pin16: V_EN 3.3V, Pin17: GND)
              │
              └──► Fast Switching PA Fixture (PA Enable)

5V USB Power Supply
    │
    └──► Fast Switching PA Fixture (V_DD)

NI cRIO
    ├──► NI 9227: DC PA Current (Ch0)
    ├──► NI 9229: DC PA Voltage (Ch0)
    ├──► NI 9238: AC Current (gNB ch0 / RU ch1)
    └──► NI 9244: AC Voltage (L1, N)