1. Network Diagrams for HMD based VR Service
SangKwon Jeong, JoyFun Inc.,
HyunSam Kang, JoyFun Inc.,

2. Compliance with IEEE Standards Policies and Procedures
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The contributor acknowledges and accepts that this contribution is subject to
The IEEE Standards copyright policy as stated in the IEEE-SA Standards Board Bylaws, section 7, and the IEEE-SA Standards Board Operations Manual, section 6.1,
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3. Cybersickness Reduction Working Group
IEEE 3079
Cybersickness Reduction Working Group
[Dong Il Seo and
Network Diagrams for HMD based VR Service
Date:
Author(s): Sangkwon Jeong, HyunSam Kang
Name
Affiliation
Phone [optional]
[optional]
Sangkwon Jeong
JoyFun Inc.,
HyunSam Kang

4. Total Motion-to-Photon Latency ≤20ms
VR System
Total Motion-to-Photon Latency ≤20ms
HMD
Motion
Input
New Image
Output
1ms ⑦ ①
Pixel
Switching
1ms
IMU
90Hz OLED Display 11ms ⑥
Write Display ② ⑤
Local Content Server
Data Processing Unit
2ms ③ ④
Remote Content Server
Data Processing Unit
2ms
Case
Status of each node
Remarks ① ② ③ ④ ⑤ ⑥ ⑦ 1
direct
Wired connection
(e.g. HDMI)
Wired WAN
chip
display
Panel
Wired Network
(WAN)
VIVE / Oculus /
PS VR

5. VR System Access Point or Base Station
Total Motion-to-Photon Latency ≤20ms
HMD
Motion
Input
New Image
Output
1ms ⑨ ①
Pixel
Switching
1ms
IMU
90Hz OLED Display 11ms ⑧
Write Display ② ⑦
Data Processing Unit ③ ⑥
Access Point or Base Station
Remote Content Server ④ ⑤
Data Processing Unit
2ms
Case
Status of each node
Remarks ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ 2
direct
chip
Wireless
LAN
WAN
display
Panel
Wireless Network
Gear VR or
Oculus GO 3
Cellular network
Mobile Network

6. Total Motion-to-Photon Latency ≤20ms
VR System
Total Motion-to-Photon Latency ≤20ms
HMD
Motion
Input
New Image
Output
1ms ⑦ ①
Pixel
Switching
1ms
IMU
90Hz OLED Display 11ms ⑥
Write Display ② ⑤
Local Content Server
Data Processing Unit
2ms
Case
Status of each node
Remarks ① ② ③ ④ ⑤ ⑥ ⑦ 4
direct
LAN /
Wireless connection
n/a
chip
display
Panel
Local Network
VIVE / Oculus /
PS VR

7. Total Motion-to-Photon Latency ≤20ms
VR System
Total Motion-to-Photon Latency ≤20ms
HMD
Motion
Input
New Image
Output
1ms ⑦ ①
Pixel
Switching
1ms
IMU
90Hz OLED Display 11ms ⑥
Write Display ② ⑤
Local Content Server
Data Processing Unit
2ms ③ ④
Remote Content Server
Data Processing Unit
2ms
Case
Status of each node
Remarks ① ② ③ ④ ⑤ ⑥ ⑦ 5
Sensor
Network
Wired connection
(e.g. HDMI)
n/a
chip
display
Panel
Motion Sensing
Whole kinds HMD

8. VR System Total Motion-to-Photon Latency ≤20ms HMD ⑦ ① ⑥ ② ⑤ ③ ④
Input
New Image
Output
1ms ⑦ ①
Pixel
Switching
1ms
IMU
90Hz OLED Display 11ms ⑥
Write Display ② ⑤
Access Point or Base Station
Access Point or Base Station ③ ④
Remote Content Server
Data Processing Unit
2ms
Case
Status of each node
Remarks ① ② ③ ④ ⑤ ⑥ ⑦ 6
direct on
Board
Cellular network /
Wireless
LAN
chip
display
Panel
Network Handover
Gear VR or
Oculus GO

9. Background Information
The purpose of this document is to find a way to minimize the VR sickness.
Out of all factors causing the VR sickness, motion-to-photon latency is considered as this is the only factor that matters to the network.
Maximum tolerable motion-to-photon in VR system is 20 ms.
VR system has some fixed latency from the hardware component such as display
Current commercial HMDs exist in two types
Stand Alone Type
All VR content are either rendered or decoded by the embedded processing unit.
Display Type
All VR content are either rendered or decoded by the external device such as PC or gaming console.
For the purpose of network analysis, we do not consider the Stand Alone type HMDs as no network issue exist here.
The following diagrams include the cases where the Display Type HMDs are used.

10. Total Motion-to-Photon Latency ≤20ms
Stand Alone Type
VR System
Total Motion-to-Photon Latency ≤20ms
HMD
Motion
Input
New Image
Output
1ms ⑤ ①
Pixel
Switching
1ms
IMU
90Hz OLED Display 11ms ④
Write Display ② ③
Data Processing Unit
No network latency exist in the connection sections 2 and 3

11. Total Motion-to-Photon Latency ≤20ms
Display Type
VR System
Total Motion-to-Photon Latency ≤20ms
HMD
Motion
Input
New Image
Output
1ms ⑤ ①
Pixel
Switching
1ms
IMU
90Hz OLED Display 11ms ④
Write Display ② ③
Data Processing Unit
Network latency exist in the connection sections 2 and 3

12. * LAN: wired or wireless
Case 1
HMD is connected to a local content server such a PC or a gaming console by a wired or wireless network.
VR content is being rendered or decoded in the local content server and HMD is receiving the VR content through either a wired or a wireless network.
Local Content Server
LAN
HMD
* LAN: wired or wireless

13. Case 2
HMD is connected to a remote content server such as cloud rendering by wired and wireless network.
VR content is being rendered or decoded in the remote content server and streamed to the HMD.
The remote content server is connected via WAN as the remote content server is located outside of the local area.
Remote Content Server
WAN
HMD
* WAN: wired + wireless

14. * LAN: wired or wireless * WAN: wired + wireless
Case 3
This is an extended version of case 1 – more than one VR system are connected to the remote content server.
HMD is connected to a local server like case 1 and the local content server is rendering or decoding VR content and send it back to the HMD.
The remote content server in this case is computing the content sent by the local content servers and redistributing the calculated data back to the local content servers rather than rendering the content in local content server.
Remote Content Server
WAN
Local Content Server
Local Content Server
LAN
LAN
HMD
HMD
* LAN: wired or wireless
* WAN: wired + wireless

15. Case 4
This is an extended version of case 2 - more than one HMD are connected to the remote server.
HMD is connected to a remote server like case 2 and the remote server is rendering or decoding VR content and send it back to the HMD.
Remote Content Server
WAN
HMD
HMD

16. * LAN: wired or wireless * WAN: wired + wireless
Case 1
Case 2
Case 3
Local Content Server
Remote Content Server
Remote Content Server
LAN
WAN
WAN
HMD
HMD
Local Content Server
Local Content Server
LAN
LAN
Case 4
Remote Content Server
HMD
HMD
WAN
* LAN: wired or wireless
* WAN: wired + wireless
HMD
HMD