## 1 Introduction  
Network operators and system administrators are interested in the mixture of traffic carried in their networks for several reasons. Knowledge about traffic composition is valuable for network planning, accounting, security, and traffic control. Traffic control includes packet scheduling and intelligent buffer management, to provide the quality of service (QoS) needed by applications. It is necessary to determine to which applications packets belong, but traditional protocol layering principles restrict the network to processing only the IP packet header. Virtual reality (VR) devices are novel, and attractive consumer electronics that can provide an immersive VR user experience (UX) [1, 2]. In order to enhance the UX of VR services, there have been significant efforts to enhance not only its video and audio quality and interaction delay, but also the convenience of VR device connections to VR consoles, or VR-capable personal computers (PCs). Therefore, consumers in the VR market require high-resolution and comfortable VR devices. In order to provide a comfortable VR service environment without the need for wires, a wireless communication scheme with low latency needs to be employed for VR devices. However, high-resolution features are not only a challenge with respect to imaging equipment, but also for wireless interfaces. Therefore,we need to find the trade-off between these two features, i.e., reliable wireless connection and high-resolution video. Wireless local area network (WLAN) is the most popular unlicensed-band wireless communication interface, which has a low cost while achieving high data throughput. Because some categories of IEEE 802.11 are designed to replace wired video interfaces, including high-definition multimedia interface (HDMI), IEEE 802.11-based WLAN can provide very high data rates. In order to meet the high data-rate requirement of high-resolution video transmission, the IEEE 802.11 working group extended IEEE 802.11 standards to support the 60-GHz frequency band with a wide bandwidth. IEEE 802.11 ad is the amendment standard, to operate IEEE 802.11 in the 60-GHz frequency band. In particular, IEEE 802.11 ad utilizes the 2.16-GHz bandwidth to achieve a high data rate. However, IEEE 802.11 ad has a relatively short communication range, owing to high-frequency band operation under indoor environments [3; 4]. IEEE 802.11 ay is the enhanced version of IEEE 802.11 ad, with the support of channel bonding and multiple spatial streams [5]. Although these 60-GHz WLAN standards can be considered as a wireless VR interface for high-resolution video transmission, future VR systems will require real-time interactive control between multiple VR users. Some applications related to gaming industries have been adopting multiuser augmented reality (AR) systems to provide enhanced gaming experiences in the living room [6]. Because VR consumers have already experienced these multi-user AR systems, multi-user VR also needs to be provided to satisfy the needs of VR consumers. The sharing of VR experiences with nearby users is expected to provide much more immersive VR to VR consumers [6; 7; 8]. Wireless multi-user VR systems based on IEEE 802.11 standards can be described as in Figure 1, which shows the elements of wireless multi-user VR systems, VR data flows, and delay components of VR services. In order to provide an immersive VR interaction experience, each component of the VR system shall provide proper feedback, based on its sensing data. From delay components of Figure 1, the VR interaction delay of a wireless VR system, \(T_{vr}\), can be described as follows. \[T_{vr}=T_{sensing}+T_{procL\_in\_device}+T_{transfer\_UL}+T_{proc\_in\_PC}+T_{ transf\_DL}+T_{proc2\_in\_device} \tag{1}\]  
VR devices shall track motion and command of users by using sensing components. The sensing components may cause a delay, depending on their sensing performance. This delay is considered as \(T_{sensing}\).