A recent research implementation shows that a working 5G base station can perform radar-like sensing while continuing to provide normal mobile communication service.
Researchers Karim Saifullin, Sajid Ahmed and Mohamed-Slim Alouini integrated real-time OFDM radar processing directly into an OpenAirInterface (OAI) 5G base station. Their system reused the existing 5G communication waveform for sensing rather than transmitting a separate radar waveform.
This is a useful practical development for Integrated Sensing and Communication, commonly called ISAC. So, now let us see how Researchers Demonstrate Real-Time Radar Sensing Inside a Live 5G Base Station along with Accurate LTE RF drive test tools in telecom & RF drive test software in telecom and Accurate Indoor cellular coverage walk testing tool in detail.
Using the 5G Signal for Two Functions
A normal 5G base station transmits OFDM signals carrying data to connected devices. These radio signals also interact with physical objects around the base station.
When the transmitted signal reaches an object, part of the RF energy is reflected. By processing these reflections, information about the target’s range and movement can be extracted.
The researchers implemented this processing within the OAI gNB itself.
The radar processing removes the known communication symbols and creates range-Doppler information from the received signal. Detection is then performed in real time. The main point is that the normal 5G waveform does not have to be modified to support the sensing operation.
The implementation achieved a nominal range resolution of 2.57 metres and velocity resolution of 0.28 metres per second.
This demonstrates that sensing is not limited to offline signal processing or a separate radar system. It can operate as part of an active 5G base-station process.
Communication Continues During Sensing
One of the more useful results concerns the effect on normal mobile traffic.
The researchers connected a commercial UE to the same carrier while radar sensing was active. Their measurements showed no measurable difference in the estimated downlink throughput when sensing was enabled. The sensing bandwidth also followed the radio resources allocated by the scheduler.
This is an important engineering result for ISAC.
If sensing requires separate spectrum or significantly reduces user throughput, deployment becomes more difficult. Reusing an existing communication waveform provides a different approach: the same RF transmission can support communication and environmental sensing.
The AI-RAN Alliance has previously demonstrated a related ISAC concept in which commercial 5G waveforms were reused as radar signals to detect and track objects that were not connected to the mobile network. Potential applications identified included pedestrian detection, occupancy sensing, drone detection and perimeter monitoring.
Real-Time Processing Inside the gNB
Processing load is another practical issue.
The researchers measured the timing of the sensing worker and reported a conservative utilisation bound of 58.4%, with no dropped sensing soundings during operation.
They also identified hardware-specific RF issues during testing.
A carrier-dependent transmit-to-receive phase rotation was observed on the USRP X300 hardware. Selecting a carrier aligned with the tuning grid improved clutter suppression and reduced coherent integration loss. This shows why ISAC development requires RF hardware testing as well as signal-processing work.
Connection with O-RAN
The implementation goes beyond local sensing at the base station.
The researchers developed an E2 service model called E2SM-RADAR. Radar detections and processed sensing information can be exported from the gNB to a near-real-time RAN Intelligent Controller.
The RIC can then support functions such as object tracking, micro-Doppler analysis and classification.
This creates an interesting direction for O-RAN.
A future RAN could potentially provide communication KPIs and physical sensing information through the same network architecture. Applications could consume this information without requiring every site to operate an independent radar platform.
What This Means for Future Mobile Networks
5G was primarily designed as a communication system. Research around 5G-Advanced and 6G is examining how radio infrastructure can provide communication and sensing from shared network resources. 3GPP-related ISAC work has considered applications including highway intrusion detection, railway monitoring, smart-home sensing, rainfall monitoring and other environmental sensing cases.
This OAI implementation provides useful evidence at the system level.
The base station was running real-time sensing. A commercial UE remained connected. The existing OFDM waveform was retained. Radar detections were processed online and delivered through an O-RAN interface. Downlink throughput estimates showed no measurable change with sensing enabled.
There is still significant work required before this type of sensing becomes a standard mobile-network function. Detection accuracy, RF hardware, interference, scheduler behaviour, sensing coverage, multi-target operation and processing capacity all need further evaluation.
Still, the experiment shows something technically significant: a 5G base station can potentially become both a communication node and a sensing node using the RF signal it is already transmitting.
About RantCell
RantCell provides smartphone-based and CPE-based network testing for 4G, 5G and private cellular networks. The platform enables engineers to collect RF and performance KPIs, run automated tests, upload results to the cloud and analyse network behaviour through dashboards and reports. It is used for drive testing, indoor walk testing, benchmarking, network monitoring and application-level service testing. Also read similar articles from here.