5G Network Slicing Interview Prep: Must-Know Questions and Answers

Learning Objectives:

1. Understanding the Driving Factors Behind Network Slicing and Its Evolution from Previous Generations of Mobile Networks
2. Defining and Explaining the Concept of Network Slicing in 5G
3. Understanding the Role of Slice Management and Orchestration
4. Understanding the Standardization Efforts Related to Network Slicing

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A) Understanding the Driving Factors Behind Network Slicing and Its Evolution from Previous Generations of Mobile Networks

Question 1: How did the limitations of 4G, particularly its consumer-centric approach and challenges with cellular IoT integration, contribute to the development of network slicing in 5G?

Answer 1: 4G, while a significant advancement, primarily focused on enhanced mobile broadband (eMBB) for consumers. Its one-size-fits-all architecture struggled to efficiently accommodate the diverse requirements of IoT applications, which range from low-latency, mission-critical control (like autonomous vehicles) to massive machine-type communication (mMTC) with millions of low-bandwidth devices. This inflexibility and the increasing demand for diverse services with varying performance needs drove the development of 5G network slicing, enabling customized network instances tailored to specific use cases.

Question 2: Why is the adoption of standalone 5G crucial for implementing network slicing, and how does it differ from previous approaches like dedicated core networks (DCN) in 4G?

Answer 2: Standalone 5G (SA) is crucial for realizing the full potential of network slicing because it decouples the 5G core network from the 4G core. This allows for more flexible and independent slice creation and management, unlike 4G’s DCN approach, which still relied on the shared 4G core and offered limited customization. SA 5G’s cloud-native architecture and service-based interfaces enable dynamic resource allocation and optimized performance for each slice.

Question 3: Considering the slower-than-expected growth of cellular IoT in 4G, what lessons can be applied to ensure the successful adoption of network slicing in 5G, and what challenges might operators face in achieving widespread adoption?

Answer 3: Learning from 4G’s cellular IoT challenges, successful 5G slicing adoption requires addressing complexity and cost. Operators need to simplify slice creation and management, making it easier for customers to define and deploy slices. Cost-effective solutions are essential to attract diverse use cases, especially for price-sensitive IoT applications. Challenges include ensuring interoperability between different vendors’ equipment, managing the complexity of a multi-slice environment, and demonstrating clear ROI to potential customers.

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B) Defining and Explaining the Concept of Network Slicing in 5G

Question 1: Explain the concept of a network slice in 5G. How does it leverage the three main domains (RAN, Core, and Transport) to provide specific network capabilities for different customers or market verticals?

Answer 1: A network slice in 5G is a logically separate, self-contained portion of the network infrastructure, customized to meet specific performance requirements. It draws resources from the three main domains: the Radio Access Network (RAN) for radio connectivity, the Core network for data processing and routing, and the Transport network for backhaul connectivity. Each slice can be configured with dedicated resources and optimized parameters in each domain, enabling tailored network capabilities for different customers or verticals, such as low latency for autonomous vehicles or high bandwidth for video streaming.

Question 2: Network slices are touted as being logically separate from each other. Describe what this entails in terms of resource allocation, configuration, and management within the physical infrastructure.

Answer 2: While sharing the same physical infrastructure, logically separate slices operate independently. This means each slice has its own dedicated allocation of resources (bandwidth, computing power, etc.), its specific configuration parameters (latency, security policies, etc.), and its individual management functions. This isolation prevents interference and ensures each slice performs as intended, regardless of the activities in other slices.

Question 3: What are the key characteristics that differentiate one network slice from another, and how are these characteristics determined and agreed upon between the mobile service provider and the network slice customer (NSC)?

Answer 3: Key characteristics differentiating slices include performance metrics (latency, bandwidth, reliability), security requirements, allowed functionalities, and cost. These are determined through service level agreements (SLAs) between the service provider and the NSC. The SLA outlines the specific requirements of the NSC and the guarantees provided by the provider, ensuring a clear understanding and agreement on the slice’s characteristics.

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C) Understanding the Role of Slice Management and Orchestration

Question 1: Discuss the importance of network slice lifecycle management. What are the key stages involved in creating, maintaining, and terminating a network slice, and what challenges might arise in managing a large number of slices concurrently?

Answer 1: Network slice lifecycle management is crucial for efficient operation. Key stages include design (defining slice requirements), instantiation (allocating resources), activation (making the slice operational), modification (adjusting parameters), and termination (releasing resources). Managing numerous slices concurrently can be complex, presenting challenges in resource allocation, orchestration, fault isolation, and ensuring performance guarantees across all slices.

Question 2: Describe the role of the Network Slice Template (NST) in the network slicing process. How does it capture the requirements of the NSC and translate them into actionable parameters for the RAN, Core, and Transport networks?

Answer 2: The NST acts as a blueprint for a network slice. It captures the NSC’s requirements (e.g., latency, bandwidth, security) and translates them into specific parameters for each domain (RAN, Core, Transport). This allows the network to automatically configure and deploy the slice according to the predefined template, ensuring consistency and efficiency.

Question 3: Explain how independent monitoring and analytics are implemented within individual network slices. Why is this independent monitoring crucial for both the service provider and the NSC, and what technical challenges does it present?

Answer 3: Independent monitoring utilizes dedicated probes and collectors within each slice to gather performance data. This data is then analyzed to assess the slice’s health, identify potential issues, and ensure SLA compliance. This is crucial for both the provider (to guarantee service quality and optimize resource allocation) and the NSC (to verify performance and address specific needs). Challenges include the complexity of collecting and correlating data from different domains and the need for scalable monitoring solutions.

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D) Understanding the Standardization Efforts Related to Network Slicing

Question 1: Identify the key standardization bodies involved in network slicing and describe their respective roles. How do these organizations collaborate to ensure interoperability and consistency in network slicing implementations across different vendors and operators?

Answer 1: Key bodies include 3GPP (defining the technical specifications), GSMA (representing mobile operators and promoting interoperability), ETSI (developing standards for telecommunications), and NGMN (an operator-led forum focusing on 5G requirements). They collaborate through liaison statements, joint working groups, and participation in each other’s meetings to ensure alignment and consistency, fostering a unified approach to network slicing.

Question 2: Discuss the importance of 3GPP specifications like 23.501, 23.502, and 28.530 in defining the architecture, procedures, and management aspects of network slicing. How do these specifications contribute to the overall functionality and standardization of network slicing?

Answer 2: 3GPP specifications are fundamental. 23.501 defines the overall system architecture for 5G, including network slicing concepts. 23.502 specifies the procedures for managing slices, while 28.530 focuses on management aspects. These specifications provide a common framework for vendors and operators, ensuring interoperability and enabling a standardized approach to implementing network slicing functionality.

Question 3: What is the significance of GSMA NG 116 and other GSMA documents in the context of network slicing? How do they complement the 3GPP specifications and contribute to the practical implementation and deployment of network slices?

Answer 3: GSMA documents like NG 116 focus on the operational and business aspects of network slicing, complementing the technical focus of 3GPP. They provide guidance on use cases, service level agreements, and commercial frameworks, bridging the gap between technical specifications and practical implementation. This helps operators and vendors translate 3GPP standards into deployable solutions.

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