Abstract: The opportunity of virtual technology VR is coming, the next year will usher in the rapid development of VR period. By reviewing and analyzing the development process of VR, this paper objectively points out the network bottleneck of VR development and application promotion. By analyzing the technical support needed for VR realization, it further points out the promoting effect of 5G network on VR development. At present, the application field and direction of 5G+VR are further prospecting the rapid development trend of VR technology under 5G high-speed communication technology.

Keywords: virtual reality technology, development history, THE realization of VR, 5G+VR

1 Overview of Virtual reality technology (VR)

Virtual Reality (VR), also known as "magic technology" and "Virtual environment", originated in the 1930s, but was limited by the technology at that time could not be developed and popularized. In the 21st century high - tech rapid development under the environment of rapid development. VR system combines computer graphics, simulation, artificial intelligence, sensor, display, network such as the high and new technical results, put the collected all the data in real life, through the computer system is converted into electrical signals, then transported to various output devices, and then make it into people to perceive the phenomenon such as vision, touch, hearing. These virtual phenomena can be real in reality or imaginary virtual objects, and a virtual three-dimensional space world can be generated by simulation, so that the experiencer can have the feeling of being on the scene.

Although virtual reality technology originated in the 20th century, it has only been applied in scenarios such as pilot flight simulation and military simulation training because of the large technical hardware equipment and high cost to implement it. Only with the recent rapid improvement in the hardware performance of electronic devices, and the development of low-power, high-frequency processors, high-resolution, high-refresh rate display screens, and sophisticated, accurate gravity and gyroscope sensors, has VR begun to reach the masses, relying on computers and smartphones. At the same time, VR applications also put forward higher standards for network operation. The rapidly developing 5G technology can meet the demand of 1000 times more traffic growth in the future, so it can be said that the future 5G network will make most of the applications of VR technology become reality.

2. The development of virtual reality technology (VR)

After half a century of development, virtual reality technology (VR) can be roughly divided into the following four stages:

The first stage: conceptual germination, before the 1950s. The concept of virtual reality (VR) appeared in the 1930s, but was limited by the development of technology at that time. The concept of virtual reality first appeared in a 1935 science-fiction short story by S.G. Weinbaum, who described the novel's protagonist Pygmalion's strange experience of entering another world after wearing special goggles. The simulator designed by Edward Link in 1929 to train pilots with sound dynamic simulation technology was the stage that covered the idea of virtual reality.

The second phase: technology exploration phase, 1950s to 1970s. In 1962, Morton Heilig developed a device named Sensorama with the help of mechanical, sound, light, electronic and other technologies at that time, which can simultaneously experience multiple senses (hearing, vision, taste, and smell) in five short films. In 1968, Ivan Sutherland successfully developed a helmet stereo display (HMD) with a tracker. In 1972 Nolan Bushell developed Pong, the first interactive video game.

The third stage: breakthrough development stage, 1970s to 1990s. The rapid development of virtual reality technology, along with optical technology and other haptic devices, makes it possible for users to move and interact in virtual Spaces. Jaron Lanier founded VPL Research in 1985 to Research several virtual reality devices, such as data gloves, eyeglass phones, volume controls, etc., making virtual reality widely known. In 1987 Jim Humphries designed and developed the first prototype of the binocular Omnidirectional monitor (BOOM). That same year, J.Lanier first coined the term "virtual reality." As the founder of Vision Programming LABS, he developed virtual reality devices such as data gloves and videphone headsets, and was the first company to sell virtual goggles and gloves.

The fourth stage: industrial application stage, 1990s till now. In 1991, Japan's SEGA Corporation (SEGA) released SEGA VR virtual reality headset arcade games and home console, through the use of LIQUID crystal display screen, stereo headphones and inertial sensors, the system can track the head movement of the player and game feedback; The Virtuality game, released the same year, included a helmet and exoskeleton glove, the first THREE-DIMENSIONAL virtual system; 1994 SEGA VR-1 Motion Simulator Arcade, capable of tracking head movements and drawing stereoscopic 3D images; Philip Rosedale founded Linden Lab in 1999 to focus on hardware that allows computer users to fully immerse themselves in 360-degree virtual reality. Since the beginning of the 21st century, virtual reality technology research has entered a stage of rapid development thanks to breakthroughs in graphics processing, motion capture and other related technologies. In 2007, Google launched Street View on Maps, which combines street images with maps to naturally display street-level live images. To make navigation easier, Google introduced 3D street View images in 2010. Virtual reality in this stage of rapid progress, theory and technology synchronous leap-over a large range. In 2012, Google unveiled its Virtual reality goggles, Google Glass, and Oculus unveiled its vr headset, Oculus Rift. With the launch of Samsung Gear VR and Google Cardboard in 2014, the availability of VR devices has increased and users are exploring the possibilities of VR more widely. Then, in 2016, HTC began selling the HTCVive. With the emergence of the most competitive leading products in the field of VIRTUAL reality head-mounted display equipment and the competitive momentum of industry development, 2016 is also seen as a key year for the development of virtual reality technology. In 2018, walmart began experimenting with the use of VR for employee training and will invest in 17,000 Oculus headsets to make VR training standard for all its units. The application of virtual reality technology continues to expand, and its social and economic value has been deeply explored.

3. Realization of virtual reality (VR)

VR is not a single technology, but a collection of many high-tech technologies. Some of these technologies are mature, while others are still in their early stages of development.

(1) Capture of user intention: This is an input mode, similar to the user's communication through mouse, keyboard and computer. VR technology can realize human-computer interaction through user's gestures and other body movements, which can also be seen as the machine's re-understanding of user needs. The vast majority of VR devices are head-mounted, allowing users to control the virtual world with just head movements.

(2) capture of characters: mainly reflected in the capture of users' facial expressions and body movements, to reproduce the user's appearance, mood, etc. For example, in the future, in the event of a meeting, other participants will be able to observe their every move, sadness, happiness and other states through VR devices without the presence of the person. Microsoft's Kinect can already recognize a user's facial expressions. The University of Southampton is a world leader in the analysis and processing of user actions. All kinds of movements of people are captured by optical equipment. After filtering out useless information, the motion Angle and amplitude of bones and joints of the moving parts of the people being observed can be measured. And the measured data can be very accurate to describe the movements of the observer.

(3) Capture of the environment: In order to reproduce the real world in the virtual reality world, there are high requirements on video shooting and geometric capture technology. Both of these techniques are applied to image processing. After setting, punctuation, image correction, panorama Mosaic and color balance, the real scene can be completely restored in the virtual reality world. Image correction is particularly important. When VR devices are used, the image needs to pass through the double convex lens before it enters the human eye. During this process, the image is distorted by refraction. In order to show the image more similar to the real scene, the image needs to undergo distortion processing first, to ensure that it is more convenient for human cognition when it reaches the human eye after passing the double convex mirror.

(4)VR real-time service: aims to realize the synchronization of local and remote characters' action scenes. Virtual reality THE VR device collects user information, reproduces the actions of characters in the virtual environment, uploads the collected actions to the cloud, and then transmits them to the remote VR device through the cloud to realize the synchronization of the actions of characters on various devices. The virtual scene information interacts with the cloud in real time to achieve synchronization.

The biggest bottleneck in implementing the above VR services is the need to solve the transmission capacity of ultra-high speed data streams. For example, only the broadband needed to transmit hd scenes. Assuming that a single scene image consists of 1920×1080 pixels and each pixel occupies 24 bits, a single scene image consists of 1920×1080×24 bits. Generally, the scene seen by human eyes is composed of 25 frames per second, so the amount of data transmitted per second for the scene transmission is 1920×1080×24×25, about 1.244Gbps. If broadband is considered only, the transmission scenario can compress the data stream through encoding technology.

Another bottleneck of realtime VR service is the requirement of time delay, which puts forward a higher requirement for network broadband, that is, more than 1Gbps. In the existing LTE technology, the transmission time interval is 1ms, and the minimum round-trip time of the system is about 10ms, which cannot meet the delay requirements of VR real-time service. 5G technology can just meet the requirements of real-time VR service for network broadband and delay. Existing research shows that the peak transmission rate of 5G network technology can now reach 10Gbps. As for the development trend of delay, the transmission time interval and the minimum round trip time of 5G network will be controlled within 10-25μm and 0.1ms. The rapid development of 5G network has laid a solid foundation for VR and helped the rapid development of VR become a reality.

4 5G+VR application field

5G(Fifth Generation mobile Communication Technology) is the latest cellular mobile communication technology. It uses a higher band of millimeter wave spectrum than traditional 2G/3G/4G/WIFI networks. Massive MIMO technology, orthogonal frequency division multiplexing (OFDM) technology, space division multiple access (SCMA) technology, simultaneous full-duplex CCFD in the same frequency, 3D beam forming, AND D2D(terminal and terminal can communicate directly under the same base station without going through the base station) technology are combined to greatly improve the spectral efficiency.

4.1 5 g + VR live

The VR industry chain has been well prepared, and high-definition VR application solutions have been widely used in the current 5G high-speed network and mature mobile scenarios. Taking ultra-high-definition VR live broadcast as an example, the solution is shown in the following figure.

Li Qingpu -5G networks lead the future development of VR technology

Uhd VR live broadcast system is mainly composed of VR panoramic camera coding all-in machine, 5G base station, 5GCPE, CDN, Light cat +5GWIFI, AND VR head display. The functions and functions of each part are as follows:

VR panoramic camera coding all-in-one: 360-degree panoramic camera can shoot and cover the scene without blind spots. Equipped with 6-8 fish-eye cameras, it has 360-degree panoramic Field of View (FOV), syntheses and codes panoramic video images into VR video streams, and pushes THE VR video streams to the telecom CDN.

5GCPE:Customer Premise Equipment can relay 5G signals to emit WIFI signals so that surrounding mobile terminals and devices can access 5G high-speed networks through WIFI.

5G base station: The core equipment of 5G network, which provides wireless coverage and realizes wireless signal transmission between wired communication network and wireless terminals. At present, 5G network mainly works in the 3000-5000mhz band. Because the higher the frequency, the greater the attenuation in the process of signal transmission, so the density of 5G network base station will be higher.

CDN: Content Delivery Network(CDN) is an intelligent virtual Network built on the basis of the existing Network. Through load balancing, Content distribution, scheduling and other technologies of the central platform, CDN dispatches users' access requests to edge servers deployed in various places so that users can obtain the required Content nearby. For example, VR live video streaming improves user access response speed and hit ratio.

Light Cat +5GWIFI: The new generation light cat supports 5G band gigabit WIFI, which can provide a stable data transmission channel for uHD VR live broadcast.

VR headset: A virtual reality headset display device, which closes people's vision and hearing to the outside world and leads users to feel that they are in a virtual environment. The display principle is to use the left and right eye screens to display the right and left eye images, through an eccentric free-form lens, so that the image becomes similar to the big screen picture, at the same time, the human eye to obtain this information with differences in the mind after the three-dimensional sense.

4.2 5 g + VR training

In today's society, business operation is fast and changeable, and workers in various fields need to constantly adapt, learn and change to keep up with the pace of social progress.

Realistic VR environment simulation greatly deepens the immersion of training, makes training skills and thinking come into play at key times, and is conducive to helping VR training complete standardized training more effectively. VR training not only speeds up skill learning, but also helps companies and employees better allocate real-world skills to job roles and positions.

4.35G +XR mixed reality

With 5 g network high speed development and widely use of graphics processing and operation will be more on the network processing, real-time ray tracing and variable ratio coloring (VRS), and other powerful new graphics can use powerful operation ability to render the clouds, using mixed reality based on video perspective can let users in the immersive virtual environment physical interface operation, Change training, simulation, and virtual prototyping. Mixed reality replaces holograms with realistic images, allowing users to control every pixel they see.

5 conclusion

With the continuous progress of technology, VR has gone through four stages from development to development and then to wide application. These four stages clearly show the unique technical characteristics of VR technology and requirements for the network. In order to realize VR to capture the user's intention, to capture the characters, to capture the environment, especially to realize THE real-time SERVICE of VR are inseparable from the network. No matter VR live broadcast, VR training, XR has been widely used with the help of 5G high-speed network. With the help of large broadband and low latency brought by the commercial use of 5G network, VR will break through the broadband bottleneck in the future, get rid of the trial phase and enter the large-scale commercial use phase.

reference

[1] Wang Y, Wang Y, Wang Y, et al. Virtual reality [J]. Journal of Computer Science and Technology,2018(1): 1-11.

[2] Yang Dong. Development and Application research of 5G Driving VR [J]. Communications and Information Technology,2020(06):44-46.

[3] Zhang Zheming. VR Development Trend under 5G Technology [A]. TD Industry Alliance, Mobile Communication Magazine. LTE Network Innovation Seminar for 5G (2016) Proceedings [C].TD Industry Alliance, "Mobile Communication" magazine office: The 7th Research Institute of China Electronics Technology Group Corporation "Mobile Communication" Magazine Office,2016:3.

[4] Yuan L P. Application of VR/AR based on 5G in higher education teaching [J]. Modern information technology,2020,4(18):190-192.

[5] Xu Shuo, Meng Kun, Li Shuqin, Ding Meng, Wu Lijun. Overview of VR/AR application scenarios and key technologies [J]. Intelligent computer and application,2017,7(06):28-31.

[6] Wang Y, Wang Y, Wang Y, et al. Virtual reality based on virtual reality [J]. Television Research,2020(02):91-93.

[7] Wang Renhao.VR development history and application in the field of education [J]. Fashion Color,2019(01):92+94.

[8] Cheng GUifeng, Chen Xueliang. The development of VR is expected to return to the fast track in 2020 [J]. Communications World,2020(06):34.

[9] Jin Yi, Liu Yuanxia, Niu Li. Information and computer (theory edition),2019,31(17):126-128.

[10] Zhang Y, ZHANG Y, ZHANG Y, et al. Virtual reality technology based on virtual reality [J]. Journal of Computer Science and Technology, 2016, 25 (5): 513-522.