Best wireless technology for virtual reality (VR)?
In this post, we will review the different technologies for VR.
VR Requirements:
For VR there are 2 key requirements:
- Latency
- Bandwidth
Let's look at each of those requirements and estimate which wireless technology makes most sense.
What is the killer app?
VR needs a killer app to reach a significant number of users. If we can have 10M daily user putting on a VR headsets, then we will see the investment in content. Solving the technical issues is crucial for VR to reach such mass-market volumes.
For example, let's say that the VR killer app is being able to share your experience in real-time through Facebook. Imagine you're going to burning man and want to share it to your friends. For such application to work the 2 key requirements will need to be met. Such an application is probably 5-10 years in the future. Most likely we will see an application where the user records the experience and shares it later.
Latency
To be have a good user experience, VR needs to have low latency. We are talking in the single digit ms (5-10ms).
With Wifi, one of the main issue is CSMA (carrier-sense multiple access). This means Wifi does not have any guarantee of on the latency and receiving a packet in a busy environment could means multiple ms (even up to 100ms)[1].
Bandwidth (BW)
The BW required for VR can be quite intensive. For example for 4K, you need about 15-20 Mbps to have a smooth streaming. For VR, this can be even more since you need to support multiple scene, since the user can look anywhere. Even if you use eye-tracking detection to reduce the BW by only rendering the where is user is looking at, you could need up to 50Mbps of streaming.
Wifi is not ideal for VR
With these 2 constraints (latency and BW), it looks like wifi is not ideal for VR. This is especially because of the latency constraint.
Here comes 5G:
5G is claimed to be a 1Gbps streaming technology. It also
5G radio latency is supposed to be less than 1ms [1:1][1:2] for URLLC.
This latency is required for tactile internet [1:3]. The real-world BW for 5G should be 100Mbps. This is close to EE LTE max rate, but keep in mind this rate is only achieve if all the stars are aligned.
Please note, that if the killer app is sharing the experience to multiple users, this BW of 100Mbps will likely not be enough.
802.11ad:
Another technology that has potential is 60GHz (mm waves) technologies. The advantage is that the protocol is TDMA (instead of CSMA), so the latency issue can be solved. However, the issue with 60GHz is you need either line of sight or 1 reflection. After that, no luck, the waves are not able to through walls or through your pockets. This works for prototype, but for a fully commercial product with great user experience, this will be hard.