LTE for Intelligent Transport Systems

The automotive sector is in need of innovative connectivity solutions for enabling improved safety and transport efficiency, i.e., ITS (Intelligent Transport Systems). Enhancements to the LTE standard targeting current and future ITS use cases are already being specified and they are planned for completion in early 2017. Another candidate radio access technology being considered for the first wave of ITS services is IEEE 802.11p.

Trucks on road

Based on our research and our contribution to LTE standardization, we can now present the first comparison between LTE and IEEE 802.11p for ITS cooperative awareness safety services. Our results indicate that LTE, based on Ericsson’s standardization proposals in 3GPP, can attain communication ranges that are twice as long compared to 802.11p, both in congested urban and high speed highway scenarios.

ITS (Intelligent Transport Systems) refers to new services for the automotive industry targeting improved safety, higher traffic efficiency and a number of additional applications. Communication plays a fundamental role already in the first wave of ITS services by enabling vehicles to share positions, sensor measurements and complimentary data with each other as well as with the road and network infrastructures.

Future ITS services are being discussed for example by the Car to Car Communication Consortium (C2C-CC) and other pre-standardization forums. The 5G Automotive Vision White Paper reflects the vision of progressively enabling automated driving by relying on faster, more reliable and lower latency communications.

The first wave of ITS services can already be supported today by combining LTE for cellular access with ad-hoc connectivity between vehicles operating on ITS-designated spectrum at 5.9GHz. Cellular multicast functionalities in LTE within the MBMS framework can be exploited for distributing content of common interest to a multitude of users in a spectrally efficient way.

For the ITS ad-hoc connectivity between vehicles both LTE sidelink (also known as device-to-device) and the IEEE 802.11p are being considered as candidate radio access technologies. IEEE 802.11p was developed earlier than LTE and is limited in many ways. For example, it is unable to cope with increasing traffic demand, it lacks QoS support and reliable packets delivery, and it is unable to fulfill the radio requirements associated with future ITS services. On the contrary LTE is a future-proof integrated solution for vehicle-to-vehicle, vehicle-to-road infrastructure, vehicle-to-pedestrian and vehicle-to-network (cloud) connectivity, as pictured in figure 1.

Figure 1 Integrated connectivity options for LTE-V2X.

Figure 1 Integrated connectivity options for LTE-V2X.

3GPP is currently specifying LTE enhancements by integrating the cellular and the ad-hoc (device-to-device, or sidelink) interfaces. The sidelink enhancements for ITS will be completed in 2016 and formally frozen as part of Rel-14 LTE in early 2017.

In our research, we have compared the enhanced LTE performance to that of IEEE 802.11p by numerical simulations, taking into consideration realistic implementation constraints. Results show significant range gain for LTE-sidelink compared to IEEE 802.11p both in high speed highway and congested urban scenarios - see figure 2.

Figure 2 Estimated coverage comparison for LTE-V2V and 802.11p (DSRC).

Figure 2 Estimated coverage comparison for LTE-V2V and 802.11p (DSRC).

Ericsson Research presented these results at the European ITS Congress in Glasgow on June 6th-9th 2016 and I was honored to be a guest speaker in three panels there, examining different aspects of ITS and its technology enablers in LTE and 5G.

We expect LTE and 3GPP to play a fundamental role in enabling future demanding ITS services through the standardization of 5G technologies.

Stefano Sorrentino
Master Researcher, Ericsson Research.

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