Large-scale virtual reality (VR) enables novel art forms in large physical environments. A key technical solution in such cases is to split the rendering process between a client and a streamer. In this article, we focused on the peculiarities of VR split rendering and particularly on the performance of Wi-Fi. First, we calculated the network delay budget and then conducted a set of experiments to evaluate the single-user and multi-user performance of VR split rendering systems over Wi-Fi in terms of latency. Our findings were summarized as recommendations on: i) the frame rate, ii) the encoding bitrate, iii) the signal strength, iv) the channel bandwidth, and v) the multiple access techniques. In particular, our multi-user tests highlighted cases where using the highest settings or latest features of Wi-Fi can compromise performance. Finally, we applied our recommendations to a large-scale multi-user case study that took place physically in the multi-purpose hall of our university campus and virtually in the Turret Singers environment of SteamVR Home. This article serves as a reference to the critical aspects of VR split rendering systems over Wi-Fi.

Wi-Fi 7, based on the IEEE 802.11be amendment, is designed to increase the maximum achievable throughput, expand the range of operating frequencies, and improve latency and jitter in worst-case scenario. In the context of the discussions to shape what Wi-Fi 8 will be, the IEEE 802.11 WG is evaluating multi-AP coordination as a strategy to further improve network performance in several aspects. MAC-driven multi-AP coordination strategies include coordinated Orthogonal Frequency Division Multiple Access (c-OFDMA), coordinated Time Division Multiple Access (c-TDMA), and coordinated Spatial Reuse (c-SR). In c-OFDMA, a set of APs transmit during a Transmission Opportunity on different channels, whereas in c-TDMA, the APs take turns transmitting on the same channel during a Transmission Opportunity. Instead, in c-SR, a set of APs transmit simultaneously on the same channel and during the same Transmission Opportunity. In this paper, we focus on c-SR. We introduce a c-SR interference model and present a strategy based on the proposed model for estimating groups of APs that can transmit successfully simultaneously. We implemented the proposed approach in the multi-AP coordination framework of ns-3 that we developed to analyze c-TDMA. We then thoroughly evaluate the performance of the proposed c-SR scheme via ns-3 simulations. The proposed scheme allows increasing the system throughput of a dense deployment up to 2.3 times as well as substantially reducing the Head of Line delay.

IEEE 802.11be networks (aka Wi-Fi 7) will have to cope with new bandwidth-hungry and low-latency services such as eXtended Reality and multi-party cloud gaming. With this goal in mind, transmit opportunity (TXOP) sharing between coordinated access points (APs) may contribute to alleviating inter-AP contention, hence increasing the overall network throughput. This paper evaluates two coordinated TXOP sharing strategies: coordinated time division multiple access (c-TDMA) and coordinated-TDMA with spatial reuse (c-TDMA/SR). We show that, while c-TDMA alone does not result in any significant improvement in terms of the WLAN throughput, it lays the groundwork to implement coordinated SR (c-SR) techniques. To evaluate the performance of c-TDMA/SR, we propose a fair scheduler able to select the best subset of parallel transmissions in WLAN deployments, as well as the appropriate power levels to be used by APs and stations (STAs), leading to maximum performance. The results obtained for c-TDMA/SR show significant throughput gains compared with c-TDMA, with values higher than 140% in 90% of the considered scenarios.