Ericsson has demonstrated the use of 5G technology to detect UAVs in flight, writes Nick Flaherty. The live proof of concept integrates sensing and spatial location of passive objects into existing 5G mobile networks using 5G signals to sense the surroundings.

The Integrated Sensing and Communication (ISAC) technology uses a massive MIMO antenna system with high-speed processing to detect UAVs at a range of up to 300 m.

The system uses the same waveform for sensing and communication and reuses communication signals for sensing. The next generation networks are expected to be based on orthogonal frequency division multiplexing (OFDM), so the sensing should be based on OFDM as well. However, waveforms other than OFDM that would show superior performance and can be transmitted and received with hardware deployed for communication, could also be considered, said Robert Baldemair, principal researcher for radio concepts and performance at Ericsson.

The system uses a pulse-Doppler radar because of its easy integration into the OFDM resource grid for communication. Matched filtering of each received pulse is performed to obtain a correlation peak, which indicates the range to the target. The range resolution and accuracy improve with bandwidth, so the system uses the 5G centimetre-waveband at 7 GHz with a wide carrier bandwidth of 400 MHz. In comparison, millimetre-wave networks up to 70 GHz have a bandwidth of 100 MHz, while other 5G systems have a bandwidth of 20 MHz.

As the target UAV moves, the propagation distance from transmitter to target to receiver changes, and the phase of the received pulses varies according to the distance change and target velocity. By comparing the phase between consecutively received sensing pulses, the target’s velocity can be determined. The closer two pulses occur in time, the higher the velocity that can be unambiguously estimated. The velocity resolution improves with the total duration of the pulse train.

The processing steps of matched filtering and phase comparison to determine range and velocity are typically done jointly using a 2D Fast Fourier Transform, which transforms the received pulse train into the delay (range) – Doppler (velocity) plane.

The direction of the target relative to the receiver position is determined by multi-antenna processing such as receiver beam forming and angle-of-arrival estimation. Mobile communication systems typically have very powerful antenna systems making them ideal for ISAC systems. The target’s location is determined by combining its direction and range.

“We expect the first standardised version of ISAC to be part of the initial 6G release in Release 21,” said Baldemair. Work on this starts in 2026 and is expected to be frozen in 2029.

“ISAC represents a transformative leap forward, merging advanced communications and sensing capabilities into a unified platform,” said Dr Tom Rondeau, principal director for the FutureG Office at the US Department of Defense. “By using communication signals to sense the physical world in real time, ISAC gives wireless networks a new dimension of environmental awareness.”