## 4 Trade-Offs among Performance Parameters
### Design of 5G Wireless Network Architecture  
The design of a smart 5G wireless network, as shown in Figure 5, is an innovative solution to enable ultra-low-latency and reliable communications in emerging and near-real-time applications such as augmented and virtual reality, remote surgery, self-driving cars, and multi-player online gaming. For an interactive VR gaming arcade, a smart network design was shown in [95] to realize the performance of immersive VR gaming scenarios, characterized by reliable and minimal latency. This setup of an indoor VR gaming arcade requires very low latency for synchronization of the location and the interactions among a group of players. The HMDs of the players in [95] were equipped with multiple mmWave band access points (mmAP) connected to an edge computing network having an operational bandwidth of around 60 GHz. The edge computing network consisted of multiple edge computing servers and a cache storage unit to offload the player's tracking data and predict poses from a prediction window for every user's HD frames obtained from their real-time tasks. This network design arrangement helps maintain a trade-off between communication latency and computation latency with efficient task offloading decisions built for efficient server placement and server selection. The need to design a cellular control plane for core networks to avoid the delay experienced by end-user applications arises. This led to the design of Neutrino, a cellular control plane [96] for providing an abstraction of reliable access to cellular services by connecting the IP backbone to the base stations while ensuring lower latency at the same time. By regularly updating the user state to the user's data access established to the Internet or to other operator services, the cellular control plane overcomes the challenge of providing low latency and reliable access to the cellular core network by enabling connectivity sessions for each device. The control plane follows a consistency protocol to minimize service disruption under failures to verify if the devices are always able to receive read-your-writes consistency [97]. The latency of control plane had a direct impact on the data latency shown in the study [98], where the control functions contributing a 72.5-99.6 ms latency in session establishment can cause up to a 1.9 ms delay in data access. The Neutrino test setup utilized two dual-socket servers running Ubuntu 18.04.3 with Kernel 4.15.0-74-generic, with 18 cores per socket and a total memory of 128 GB. Further optimizations were performed of Neutrino to satisfy the acceptable bandwidth trade-off for the cellular providers and to reduce the issues of increasing overhead in messages to profit from the latency benefits. A UAV-aided wireless network design [99] can be utilized to reduce over-the-air delay through channel condition improvement techniques at both the transmitter and receiver by reducing the packet error probability to enable a reliable and low-latency communication channel in AR/VR. A remote VR gaming setup was presented in [100] using a low-latency edge rendering scheme. It utilizes two gaming laptops equipped with an Nvidia GTX 1070 GPU and Intel i7 7820 HK CPU, with both connected using Gigabit Ethernet for low-latency communication. This scheme allows the execution of a VR game by off-loading the information from an end user device to a cloud edge server to render the game based on the feedback obtained from the headset and the controller network. This setup is able to achieve an end-to-end latency of 30 ms with a bit rate of 20 Mbps for the stereo 1080p30 format. VLC, emerging as a powerful interface solution for 6G, has the potential to boost the transmission rate by utilizing a micro-LED-based photodetector [101] in AR/VR-based HMDs. This detector uses a receiver fabricated on a Si substrate that can achieve a transmission rate of more than 10 Gbps with visible light communication.