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Network slicing uses virtualization technology to cut the network into multiple, virtual, end-to-end networks, and the equipment, access, transmission, and core network of each virtual network are independent. By distributing demand, adjusting and sharing hardware resources, and improving the flexibility of the network, the cost of hardware, and the time required for network construction are reduced.

Network slicing has been deployed on the edge of the network to complement edge computing. Being close to the data source, network slicing has integrated computing, storage, and application core capabilities. Using the computing power and services provided by edge computing, it can meet the needs for low latency, massive connection services, and data aggregation and optimization, and relieve the load pressure on the core network and backhaul links.

5G network slice definition:

5G network slicing technology is used to cut the network into multiple, virtual, end-to-end, independent networks to facilitate transmission between equipment base stations and the core network. Network slicing improves the flexibility of Core Networks and Radio Access Networks (RANs), reduces latency, and increases security and the efficiency of bandwidth use etc., by scheduling the use of limited network resources.

Network slicing can be divided into horizontal and vertical parts. One example of horizontal network slicing is that a portable device cuts out part of its resources for use by wearable devices, including storage space, communication, and computing. Through edge cloud computing, the communication delay is shortened and efficiency is improved.

Vertical network slicing is the path from the device to the base station to the core network, providing different quality of service (QoS). For example, a car has services such as navigation, maps, real-time traffic conditions, communication, and entertainment. Safety is the primary consideration. Devices such as communication and entertainment may have lower QoS than other services. For example, the network slicing technology used in sports event broadcasting, some providers of TV broadcasting provide larger mobile broadband according to the Service-Level Agreement (SLA). Another is used for security monitoring and has enough QoS for fans to upload. Selfies, each with different requirements and priorities, enabling features for each slice will be distributed individually, so even if all fans celebrate a win by sharing a recorded video, it will ensure safety and broadcast traffic in the slice, with enough bandwidth.

In the 4G era, APN (Access Point Name) has become the initial form of network slicing. When a user surfs the Internet, the mobile network operator will know the user through the APN, assign the corresponding IP address to the device, and understand the network access settings. 4G also manages end-to-end service collaboration with MOCN (Multi-Operator Core Network) and DCN (Dedicated Core Networks).

In terms of 5G, network slicing is completed by SDN (Software-Defined Networking) and NFV (Network Functions Virtualization). NFV is used to separate network functions and hardware, reconfigure resources and use virtualization to improve efficiency. SDN is used to coordinate and control the network traffic settings of users and various managers, so that resources can be effectively shared among different layers of network slices.

• AMF (Access and Mobility Management Function), mainly provides registration, connection, and mobility management.
• SMF (Session Management Function) is responsible for negotiating with Data Plane, establishing, modifying, and releasing PDU (Protocol Data Unit).
• UPF (User Plane Function) is responsible for data packet inspection, routing, forwarding, and QoS processing, etc.
• UE (User Equipment), such as mobile phones, tablet computers, etc., will request Single - Network Slice Selection Assistance Information (NSSAI) to the Radio Access Network (RAN).  RAN will pass the request to the target AMF. AMF authentication of the UE's subscription requires the NSSF (Network Slice Selection Function) to provide the NSSAI belonging to the UE. The NSSF will send the UE slice conditions to the AMF. Finally, the AMF will configure the UE's slice and send a message to the UE to accept the slice registration.

The advantage of 5G network slicing is that a single network can be used to provide services according to different needs. Network operators can allocate an appropriate amount of required resources according to network slicing, which helps to improve the effectiveness and efficiency of network resource utilization. Under the baseline assumption, network expenses (OPEX) and capital expenditures (CAPEX) are effectively reduced by 40%, potential revenue is increased by 35%, and an estimated economic benefit of an overall increase of 150% is achieved, greatly improving operational efficiency and 5G network service delivery time to market.

5G network application scenarios:

1. Mobile Broadband:
   The 5G era will be oriented to applications such as 4K/8K ultra-high-definition images, holographic technology, augmented reality/virtual reality, etc. The demand for mobile broadband is higher in data capacity.
2. Massive Internet of Things:
   Massive sensors are deployed in the fields of measurement, construction, agriculture, logistics, smart cities, homes, etc. These sensor devices are very dense and most of them are stationary.
3. Mission Critical IoT:
   Mission-critical IoT is mainly used in areas such as unmanned driving, automatic factories, and smart grids. The main requirements are ultra-low latency and high reliability.

5G network slicing usage scenarios:

Smart life covers transportation, smart home, remote medical care, virtual concerts, and other aspects. To further connect life with the network, 5G network slicing can expand the scale of use and allow users to have a better user experience.

1. Automation:
   Because of the virtual network, network slicing can be operated on the software, which can be set without limitation of time and region and can be changed in a short time through an automatic mechanism. In the event of road failures or temporary maintenance works, network operators can immediately suggest vehicle rerouting through navigation, and redistribute network resources to priority maintenance works or emergency personnel and vehicles through SLA. Network slicing can provide certain QoS for autonomous driving to ensure high reliability and low latency road information. Vehicles can obtain the required information or provide information from roadside infrastructure or other vehicles to change lanes or overtake, to provide a safe distance to reduce traffic accidents.
2. Medical system:
   Telemedicine can provide services in areas with scarce medical resources or inconvenient transportation. Outpatient data, images, etc., need eMBB (Enhanced Mobile Broadband) transmission and inspection. In the future, deep learning will be used to assist wound area detection technology, etc., which will require low-latency communication in long-term care and surgery, so that doctors can determine the patient's condition. Network slicing can flexibly adjust the transmission capacity and provide lower latency, effectively slicing the data resources of the medical station through the horizontal network, while transmitting large-capacity images and files to other clinics, and effectively maintaining patient privacy.
3. Utilities:
   5G application scenarios can be extended to the energy industry, including smart power plants, smart grids, smart coal mines, smart oil and gas, and integrated energy. Network slicing can provide energy system infrastructure, formulate flexible scheduling and establish security protection. The reliability and low latency brought by 5G through network slicing technology can improve the automation of energy distribution networks. In addition to better grasping the status and management of industrial and household electricity consumption, monitoring and judgment of power grid transmission losses can be used in taking corresponding measures remotely.
4. Live market:
   The market analysis report pointed out that the global live broadcast market will be worth 50.11 billion US dollars in 2020, and it is expected to continue to grow by 20% every year in the future. Higher-quality live broadcasts and smart home devices can be controlled through network slices to adjust to the required low latency and corresponding QoS, and continue to intelligently control cameras to provide a good live broadcast experience.
   Large-scale events such as New Year’s Eve events require huge network applications and demand, including data requirements for the number of participants, communication of venue equipment such as aerial photography of drones that have been applied for, and system operations for public safety, etc. Some require low latency and a large number of devices for communication, some require different requirements such as high speed and large traffic. Through the application of SLA agreements with telecom operators, operators can provide corresponding service quality.

The technology of end-to-end network slicing collaboration can automatically manage the radio access network (RAN), transmission and access, and establish network resources through the core network for various applications. They are combined to deliver information in an end-to-end manner from the user's device to the data center. Different target customers can follow this format and have their own 5G network slicing technology.

5G slicing security concerns:

5G network slicing uses virtualized network function facilities for virtual slicing. Therefore, the security threats of 5G network slicing mainly lie in the security threats brought by network slicing itself and network virtualization. Hackers can use DoS (Denial-of-Service Attack) to steal important information of 5G slice managers after gaining access to the 5G service-oriented architecture.

Location tracking is a potential security threat for 5G slicing due to the lack of security function-related content due to 3GPP standards and specifications. According to 3GPP standards and specifications, there is no correlation between user identity and authorization tickets, and attackers can obtain data such as device location. In other words, it does not authenticate the user's identity, confirming that it belongs to the token that sent the request and associated authorization. After connecting to the edge network function of the operator's service-oriented architecture, hackers can exploit the flaws in the design of network slicing standards. To access the operator's core network and other enterprises' network slices, causing network operators and their customers to lose protection. The risk of user data, not only personal identification information, financial and payment information, authentication information, location, etc., may be illegally used, but also affect the normal communication of users. If the identity can be cross-checked and confirmed, such as whether the user is using a slice that belongs to it, and whether the IP location matches the ID situation, it should help improve reliability.

Another risk is the possibility of data leakage and fraudulent use. For example, when someone obtains an ID, slice ID, or IP address that does not belong to him as a request and authorization to use, he can enter the network as another person. The use of Transport Layer Security (TLS) authentication and communication security is not enough to protect services, nor is it enough to protect 5G networks. Communication is required between different network slices, RAN network slices, and core network slices. The interfaces between network slices are more likely to be attacked, causing network slices to fail to work properly. A DOS attack is a malicious attack designed to affect the availability of its target systems, such as a website or application. An attacker would generate a large number of packets or requests that would overwhelm the system. For slices, when an attacker accesses a slice, the resources of other slices may be consumed, resulting in insufficient resources, which may cause DoS attacks on other slices. This attack prevents message synchronization and instant updates in 5G as well as policy enforcement when there is no relevant message inside 5G to indicate overload. This mismatch could lead to abuse of 3GPP's overload control features, causing delays or interruptions to parts of the network.

5G brings not only industries but also various innovative and intelligent applications that will realize many imaginations and bring about major changes in people's lifestyles. The use of network slicing as one of the key technologies of 5G composition gives priority to solving security threats in wireless networks so that application scenarios can be presented in life more reliably, safely, and completely, to give full play to the greatest advantages of 5G networks.