V2X for Autonomous Vehicle: 5G or IEEE 802.11p?

Mahbubul Alam Uncategorized 1 Comment

In conversation with Mahbubul Alam, CTO/CMO of Movimento Group, an APTIV company.

The days of 5G complimenting 4G is just around the corner as 5G standards have been approved, accelerating the industry’s global deployment of the network. What does this mean for the automotive industry?

How will 5G influence the connected and automated drive experience?

[Mahbubul]: One of the key aspects of 5G is the uplink data rate, which is data moving from the vehicle to the cloud. Compared to 4G, 5G significantly increases the sustainable bandwidth of both the uplink as well as the downlink. But that by itself is not good enough. How do you get close to real-time decision making? This would translate back to ultra-low latency with guaranteed jitter and delivery. Second, HD mapping requires high-speed bandwidth through which massive volumes of data are transmitted and the precision of location is required to know where the object is relative to each other. The third thing is the support for high density of the vehicles per cell site – knowing that many vehicles can be close to each other and still access that kind of high sustainable data rate is very important. One thing that 5G provides, for the first time, is latency in sub-milliseconds. Today, if we look at 4G LTE we have 10-30 milliseconds a-round-trip communication, for 5G it would be under one millisecond, which is almost near real-time. The peak bandwidth of the downlink is going to be about 20 Gbps, whereas sustainable bandwidth is 1 Gbps for the downlink. But sustainable uplink is also in the order of 10 Mbps. Peak bandwidth can go in the order of 100 Mbps. Having a sustainable uplink of 10 Mbps and a sustainable download of 1 Gbps is a big deal. Then the question that rises is – are you the single one in the cell or are there more cars next to each other, can a lot of cars afford that? Compared to 4G, 5G now improves the vehicle density by 100x, it now has 100x compactness of devices/vehicles that can use the data and it would still be fine.

Last but not least, is the logical separation of the 5G network for industry/markets, unlike today’s 4G network, where you have a single network that is used by everybody from utilities, telemetry, metering, to computers to watching movies to email to end users, all using one single 4G/LTE network. In 5G there is network slicing capability where we can decide a logical network dedicated only to the autonomous drive or combine that with the connected drive experience. This means that only vehicles will be using that particular logical network and so network performance, business model, pricing, etc.  can be dimensioned to that need of vehicles. The latency can also be managed because there is only a specific kind of traffic. Currently, there is a mixed pattern which makes it difficult for 4G/3G carriers to understand where optimization is required. 5G will enable HD mapping in the cloud and then send that information back almost in real-time and this will provide a superior user experience.

Figure 1: 5G vs 4G Comparison


How does 5G compare with V2X technologies on cybersecurity and how do they suit different strategies & service offerings?

[Mahbubul]: 5G and V2X are very different things, so we are actually comparing apples and oranges. Many people confuse V2X with technology, V2X is not a technology, they are use cases for vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-pedestrian (V2P), vehicle-to-X (where X can be anything), it depends on what technology we use.

Figure 2: Vehicle-to-Anything (V2X)

Today, when people talk about V2X, what they mean is the technology called IEEE 802.11p/DSRC (Dedicated Short Range Communication), which is IEEE 802.11p similar to WiFi. In 2017, Cadillacs (General Motors) introduced IEEE 802.11p/DSRC for V2V use cases and other automotive manufacturers are expected to follow. Regulators in U.S. (U.S. Department of Transportation) and Europe have embraced IEEE 802.11p/DSRC. They are expected to make it a requirement for all new vehicles. However, there is a strong argument and push back from the cellular industry to consider 5G as an alternate solution.

5G comes from the evolution of cellular technologies such as 2G, 3G, 4G. So, the question here is the difference between IEEE 802.11p/DSRC and 5G cellular technology for vehicle use cases, both are applicable for V2X, but which one is better suited? From a security and coverage perspective, the two main components of V2X are V2V (vehicle-to-vehicle) and V2I (vehicle-to-infrastructure). IEEE 802.11p/DSRC based V2V does not require an infrastructure which means that the beacons are sent out from the vehicle and other vehicles nearby can be detected. The same thing can be achieved with 5G with cellular-vehicle-to-everything (C-V2X) support also known as 5G V2X sidelink. This kind of communication also enables device-to-device (D2D) communication.

5G supporting C-V2X is similar to 802.11p (IEEE 802.11p/DSRC) V2V communications. An assessment of LTE-V2X and 802.11p direct communications technologies for improved road safety in the EU can be found here. The study found that LTE-V2X outperformed 802.11p (IEEE 802.11p/DSRC) for road safety.  From that perspective, IEEE 802.11p/DSRC is focused on communication and the security around certificates. This can be used for 5G as well. In addition to that, 5G networks would provide better security because it is evolving from 3G/4G security and has inherent communication security built in it. IEEE 802.11p (IEEE 802.11p/DSRC) does not have the same level of communication security on its own, so we have to add higher layers of security. But if we think about the certificates, the infrastructure or the X.509 certificates, they can be in both because they are not on the communication link level, they are on a higher layer of security.

In terms of coverage, what is better suited for different strategies and services? One of the key characteristics of 5G is the support for infrastructure-less communication. What does that mean? It means that 5G has the ability to form a wireless mesh network – communication can hop from one vehicle to another vehicle, to create an ad-hoc network. IEEE 802.11p/DSRC also does not require infrastructure for V2V communication. From that perspective, they are on par. The services that the IEEE 802.11p/DSRC can provide, the same can also be provided by 5G C-V2X. In terms of different strategy, if we look at it from a WiFi perspective then we are banking on IEEE 802.11p/DSRC. If we look at it from a cellular perspective, then we want to extend the cellular capability to enable mesh networks and ad-hoc communication. The cellular V2V approach is newer whereas IEEE 802.11p (IEEE 802.11p/DSRC) has been around for many years with people doing trials and POCs.


Can 5G and IEEE 802.11p compete with each other?

[Mahbubul]: They can definitely compete with each other. If we use IEEE 802.11p/DSRC for V2X, we have to spend billions and billions of dollars to build the roadside infrastructure for V2I. A new infrastructure has to be built along the road in urban, suburban and rural areas.  To take advantage of V2I, massive infrastructure investment is required, whereas 5G has the advantage of cellular technology for broad purposes and carriers are interested to roll out 5G infrastructure in order to monetize from the different Internet of Things (IoT) use cases. In this scenario, the carriers pick up the bill of the infrastructure and they can logically separate out (slice) the infrastructure for mobile internet, for smart grids, for connected devices, for autonomous vehicles and so on. In this way, they can quickly monetize their investment in different ways and the 5G infrastructure remains a shared infrastructure. From this perspective, 5G has an advantage over IEEE 802.11p/DSRC because the cell towers and the real states, etc. can all be leveraged and used. The carriers can monetize their investment not only from one vertical industry but from multiple vertical industries and use cases e.g. retail use cases, end-user use cases, connected car use cases, automated drive use cases, utility use cases, etc. Thus, they have a much bigger pool of having a better Return on Investment (ROI). With that in mind, 5G is better suited. They can definitely compete, but from the auto industry’s point of view, all the learnings from IEEE 802.11p/DSRC V2V and V2I use cases can be leveraged on to 5G as it is just the underlying technology. It does not really matter whether you use 5G V2X sidelink or IEEE 802.11p/DSRC, what really matters is how we use the application built on top.

Is the 5G infrastructure ready to be pushed out on a national scale?

[Mahbubul]: 5G infrastructure is ready to go national because of the business reason talked about above. It is not a technical thing but the ROI for the business use cases. The business case for the carriers is well proven and they are looking to have 5G rolled out not only because of the capacity-increase but for the first time they would have the ability to monetize and provide dedicated logical networks for vertical industries and charge differently. But IEEE 802.11p/DSRC is absolutely not ready to go national. No country has billions of dollars to roll out this dedicated infrastructure only for vehicle safety.

Another thing to understand is the silicon that has to go into the vehicle. The advantage that 5G has is that silicon is produced on a massive scale for smartphones. So, the cost of them building that silicon and the robustness that they have from the 3G/4G network of billions of people using it are still unproven grounds in IEEE 802.11p/DSRC. There is no trail for even a hundred thousand people or devices using IEEE 802.11p/DSRC. There are a lot of new challenges that will appear for IEEE 802.11p/DSRC because of the inherent security of cellular technology of 3G/4G that it does not have. Of course, 5G will have its own challenges but they will pale in comparison to those that the IEEE 802.11p/DSRC will have. The cellular approach to V2I will extend to V2V as well because every car needs connectivity. It will also be applicable to V2P (vehicle-to-pedestrians) where the beacon will be released from the person’s smartphone and the car will detect it, this can prevent accidents. The best part of cellular technology is the broad applicability of it – in smartphones, in cars, in hand-held devices. The applicability is so broad that you can truly have a V2X rather than only V2V or V2I. This can be further extended to device-to-device, where bicycles and motorcycles will be able to avoid fatal accidents. The massive volume of smartphone production is going to drive down costs faster than any other technology.

The key message is that the window for IEEE 802.11p/DSRC to be implemented and to become successful is only becoming smaller and smaller. As 5G comes in, and IEEE 802.11p/DSRC does not have that kind of volume, it is not mandated and is not in the car, they are losing that advantage. Once 5G comes into the towers and cell phones, then it is going to be much more difficult to introduce a new technology and get investment only for vehicles.

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