At their 5G Joint Innovation Lab in Madrid, Spain, Telefónica and Huawei have completed a proof-of-concept (PoC) test of 5G-V2X. The test is based on the latest 3GPP New Radio (NR) Standard specification, which has been available since 22 December 2017.
Advanced 5G-V2X services include vehicle platooning, extended sensors, advanced driving and remote driving. The partners say that self-driving will require further enhancements of the 5G NR system, in conjunction with a new NR Sidelink to allow V2V communications.
The companies say the Ultra-Reliable and Low-Latency Communication (URLLC) mode for 5G NR offers the flexibility to support services with low latency and high reliability requirements of autonomous driving.
They say the PoC test demonstrated that URLLC can effectively support V2X with higher system capacity and better coverage reporting 99.999% reliability with a latency of 1ms required for autonomous driving in a typical macro cellular outdoor environment. The PoC test will lay the foundations for large-scale field trials with the upcoming commercial deployments of 5G wireless networks worldwide.
In the 5G-V2X PoC, a novel self-contained frame structure was used for radio transmission, both from the base station to the vehicle and from the vehicle to another vehicle. This is designed to allow much faster transmission feedback, enabling very low-latency communications. The flexibility of the NR system framework supports features including Polar coding for small V2X packet error correction, an optimized Hybrid Automatic Repeat Request (HARQ) procedure for increased transmission reliability, or an Inactive State for instantly sending short packets to control the car manoeuvre.
To further enhance performance, Sparse Coded Multiple Access (SCMA)-based Grant Free Access was tested. This is designed to simplify uplink access procedures to reduce transmission latency.
In the PoC, vehicle platooning is used as a typical test case for advanced V2X services, where the platoon members are controlled by the 5G NR network. The partners say the PoC showed that 99.999% reliability can be achieved within a 1ms round trip delay constraint, and the signalling overhead can be decreased by 67% compared with state-of the-art cellular systems.