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V2x: 802.11p trumps LTE and 5G

Posted: 09 May 2016 ?? ?Print Version ?Bookmark and Share

Keywords:C-ITS? vehicle-to-infrastructure? V2I? V2V? V2x?

In the United States, the National Highway Traffic Safety Administration (NHSTA) has raised the issue of privacy [17]. In a network-based solution, user data will pass through the network on its way to the cloud. Operators will need to provide the appropriate mechanisms to protect user data in the cloud and, perhaps more important, users will have to accept and trust those mechanisms. Privacy is a growing concern for everyone, so one can expect significant opposition of cloud-based systems. With an IEEE 802.11p based solution, messages don't have to go to the cloud, and this can make it easier to address privacy-related concerns.

Implications for the cellular infrastructure
The fact that cellular networks are already in place around the world is often cited as a reason to use cellular for V2x solutions. The main argument is that, since the cellular infrastructure is already there, there's no need to invest in and deploy a new infrastructure for 802.11p. But, as mentioned above, using the existing cellular infrastructure for V2x is not as simple as it sounds, because today's infrastructure isn't equipped to support the many V2x use cases that require short latency in situations of high mobility or congestion.

It's important to note that 802.11p-based technology, in the form of road-side units (RSUs), can be deployed in much of the existing roadway infrastructure, including traffic lights and traffic signs. Unlike the cellular infrastructure, which requires new base-station towers for expansion, the 802.11p infrastructure can make use of structures that are there today, and this represents a significant cost savings in terms of near- and long-term deployment. RSUs in intersections also makes sense from a system requirements point of view. Signal Phase and Timing controllers are collocated with the RSU enabling many safety, mobility and traffic efficiency applications. Intersections are where the "action" takes place.

Another aspect to keep in mind with 802.11p is that the spectrum for 802.11p-based V2x services has already been allocated worldwide. As described earlier, the 5.9GHz region includes 75MHz of bandwidth set aside for use with 802.11p-based V2x services. This is one of 802.11p's greatest assets. Countries, states, carmakers, and infrastructure providers need to prove their compliance with the standards and then they will be able to simply operate in the 5.9GHz region. No need of subscriptions, roaming agreements or similar. Today's providers of cellular services already face challenges with bandwidth, in light of growing consumer activity and expansion of the IoT, and may have difficulty meeting the technical and business requirements of V2x.

LTE Release 8 may already be part of vehicles, but it will take a long time C perhaps eight years or more C before the required cellular standards, namely LTE-A and 5G, fully support all safety-related and non-safety-related V2x use-cases. By contrast, field proven, compliance tested solutions based on 802.11p are ready right now, and can be deployed on a large scale, worldwide, at any time. Moving ahead with 802.11p means enjoying the benefits of V2x use-cases that much sooner.

At NXP, Cohda Wireless and Siemens, we believe 802.11p is the better choice for deploying V2x applications today, because it's ready to roll. But we also see the need for broader compatibility. We are working on co-existence, which will make 802.11p and LTE-A/5G more compatible, and are even considering the option to merge the two, to create a heterogeneous vehicular networking system that leverages the best of both C the ability of 802.11p to support safety-related use-cases, and the ability of LTE-A/5G to support non-safety-related use-cases.

[1] Global status report on road safety 2015 , World Health Organisation (
[2] Status of the Dedicated Short-Range Communications Technology and Applications Report to Congress , Final ReportJuly 2015 FHWA-JPO-15-218
[3] ITS Cooperative Mobility Services Event 4, ETSI (
[9] Intelligent Transportation Systems Joint Program Office, US Dept of Transportation (
[10] J. Yoshida, "NXP Beats Qualcomm, Gets First V2V Design Win," EETimes, September 2014 (
[11] A. Vinel, "3GPP LTE Versus IEEE 802.11p/WAVE: Which Technology is Able to Support Cooperative Vehicular Safety Applications?", in IEEE Wireless Communications Letters , vol.1, No.2, Apr. 2012
[12] G. Araniti, C. Campolo, M. Condoluci, A. Iera, A. Molinaro, "LTE for Vehicular Networking: A Survey", in IEEE Communications Magazine, vol.51, no. 5, pp. 148-157, May 2013
[13] Roger Lanctot, "Why Cellular vs. DSRC for V2V: Why-Fi in a Car?" StrategyAnalytics, Nov 2015 (
[14] Anders Fagerholt, "Wireless Today", ITS World Congress 2015
[15] 3GPP R1-153956
[16] 3GPP R1-153895
[17] NHTSA (National Highway Traffic Safety Administration), Vehicle-to-Vehicle Communications: Readiness of V2V Technology for Application; DOT HS 812 014 page xviii

About the authors
Alessio Filippi is Development Manager, Business Unit Automotive, NXP Semiconductors.

Kees Moerman is Sytem Architect, Business Unit Automotive, NXP Semiconductors.

Gerardo Daalderop is Senior Principal Architect, Systems & Applications, Business Unit Automotive, NXP Semiconductors.

Paul D. Alexander is Chief Technology Officer, Cohda Wireless.

Franz Schober is Product Life Cycle Manager, Siemens AG, Mobility Intelligent Traffic Systems.

Werner Pfliegl is Team Head, Product Management „Connected Mobility", Siemens AG.

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