KT has collaborated with Rohde & Schwarz and VIAVI Solutions to develop non-terrestrial network (NTN) technology that overcomes the disadvantages of long propagation delays in satellite communication environments. With this technology, a bandwidth of more than 10 Mbps is possible even between a geostationary (GEO) satellite and user device. This increased transmission efficiency was leveraged to successfully transmit full HD video. Visitors to Moble World Congress 2025 in Barcelona can see a demonstration of this technology at the KT booth in Hall 4, Stand 4A60.
On February 12, 2025, KT successfully demonstrated 5G non-terrestrial network (NTN) technology in a satellite communication environment with long propagation delays. It used a method that accurately calculates path loss between the satellite and device based on their varying distance over time, without using retransmission techniques (HARQ-less). As a result, a bandwidth of more than 10 Mbps was achieved at approximately 35,000 km between the satellite and user device, enabling full HD video transmission.
The NTN digital twin testbed from Rohde & Schwarz and VIAVI Solutions was used to develop this technology. The testbed is based on the CMX500 one-box signaling tester and the VIAVI TM500-AS2 Network Tester.
The CMX500 radio communication tester is a future-proof 5G NR test solution with an intuitive and flexible web-based user interface. It features channel emulation and fading in a single box, including all 3GPP fading profiles. The modular design can be easily customized to specific test requirements. For example, additional RF units can be implemented to support comprehensive testing of all 3GPP FR1 band combinations. FR2 capabilities are also available for most configurations, enabling greater versatility in advanced 5G NR testing.
The VIAVI TM500 Network Tester family supports early functional, system integration, capacity, performance and regression testing for 5G base stations. It simulates thousands of mobile devices to offer comprehensive testing across the entire protocol stack, from the physical layer to NAS and application layers. The tester is used with the VIAVI TeraVM, an application emulation and security performance solution, which delivers comprehensive test coverage for application services, wired and wireless networks.
Tae-hoon Kim, Managing Director of Rohde & Schwarz Korea, says: “Rohde & Schwarz has continuously worked to overcome technical challenges in satellite communication environments. This collaborative research with KT was conducted using the CMX500 platform, which meets the requirements of mobile communication technologies such as 5G and NTN, allowing us to secure the latest technology and validate advanced implementations.”
Beom-seok Seo, Country Director of VIAVI Solutions Korea, says: “We have achieved over 10 Mbps in longdistance satellite communication using HARQ-less technology. This technology has the potential in public safety operations and other similar applications.”
Jong-sik Lee, Executive Vice President of Future Network Laboratory, KT, says: “NTN is an essential technology for ubiquitous connectivity in the 6G era. In the future, KT will continue to expand communication coverage beyond terrestrial limits and into three-dimensional aerial spaces, leading the way into the 6G era.”
At MWC 2025, visitors can experience at the KT booth 4A60 in hall 4 the live demonstration of full HD video transmission between a geostationary (GEO) satellite and user device, as well as explore the NTN digital twin testbed from Rohde & Schwarz and VIAVI Solutions. Those interested in learning more about the testbed can speak with an expert at the VIAVI Solutions booth in Hall 5, Stand 5A18.
For more information on the NTN digital twin testbed from Rohde & Schwarz and VIAVI Solutions, visit: https://www.viavisolutions.com/en-us/solutions/non-terrestrial-networks