5G Wireless Network Slicing for eMBB, URLLC, and mMTC: A Communication-Theoretic View (1804.05057v2)

Abstract: The grand objective of 5G wireless technology is to support three generic services with vastly heterogeneous requirements: enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). Service heterogeneity can be accommodated by network slicing, through which each service is allocated resources to provide performance guarantees and isolation from the other services. Slicing of the Radio Access Network (RAN) is typically done by means of orthogonal resource allocation among the services. This work studies the potential advantages of allowing for non-orthogonal sharing of RAN resources in uplink communications from a set of eMBB, mMTC and URLLC devices to a common base station. The approach is referred to as Heterogeneous Non-Orthogonal Multiple Access (H-NOMA), in contrast to the conventional NOMA techniques that involve users with homogeneous requirements and hence can be investigated through a standard multiple access channel. The study devises a communication-theoretic model that accounts for the heterogeneous requirements and characteristics of the three services. The concept of reliability diversity is introduced as a design principle that leverages the different reliability requirements across the services in order to ensure performance guarantees with non-orthogonal RAN slicing. This study reveals that H-NOMA can lead, in some regimes, to significant gains in terms of performance trade-offs among the three generic services as compared to orthogonal slicing.

• The paper introduces a unified communication-theoretic approach leveraging H-OMA and H-NOMA to address the distinct needs of eMBB, URLLC, and mMTC.
• It employs outage probability models and successive interference cancellation to optimize resource allocation and manage interference effectively.
• It highlights reliability diversity as a key principle for enhancing performance trade-offs and paves the way for future multi-cell, dynamic network studies.

5G Wireless Network Slicing for eMBB, URLLC, and mMTC: A Communication-Theoretic View

This paper presents a communication-theoretic paper focused on the slicing of 5G wireless networks to support three major services: enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC). The investigation into network slicing explores both orthogonal (H-OMA) and non-orthogonal (H-NOMA) resource allocation techniques, highlighting the implications for service coexistence and interference management.

Core Concepts and Methodology

• Heterogeneous Service Requirements: The paper addresses the contrasting needs among eMBB, URLLC, and mMTC, specifically in terms of data rates, latency, and reliability. Enhanced mobile broadband prioritizes high data rates, URLLC emphasizes low-latency and high reliability, while mMTC supports sporadic transmissions from a large number of devices.
• Network Slicing: Network slicing is employed to facilitate the coexistence of these heterogeneous services within the same radio access network. It involves allocating resources to maintain performance guarantees and service isolation.
• H-OMA vs. H-NOMA: Slicing can be ortho- or non-orthogonal. H-OMA ensures no resource overlap among the services, while H-NOMA permits shared usage to improve spectral efficiency but at the potential cost of increased interference.

Analytical and Numerical Findings

Orthogonal Slicing (H-OMA)

Under H-OMA, resources are distributed orthogonally between eMBB, URLLC, and mMTC:

• eMBB: The provision of resources focuses on maximizing data rate under certain reliability constraints. The paper utilizes an outage probability model to guide optimal power and rate adaptation strategies.
• URLLC: By allocating specific frequency channels, URLLC achieves the required reliability despite low-latency demands, benefiting from increased frequency diversity.
• mMTC: Resource allocation accommodates a random set of devices, optimizing for maximal supported arrival rates under a given error probability constraint.

Non-Orthogonal Slicing (H-NOMA)

H-NOMA facilitates simultaneous service access to resources, necessitating sophisticated decoding techniques:

• eMBB-URLLC Coexistence: The use of successive interference cancellation (SIC) is analyzed, showing significant eMBB rate gains while maintaining URLLC reliability. H-NOMA proves beneficial particularly when the SNR for URLLC is higher than for eMBB.
• eMBB-mMTC Coexistence: The decoding strategy effectively prioritizes high SNR mMTC transmissions before eMBB, leveraging reliability diversity. This ensures some improvement in mMTC throughput while preserving eMBB performance.

Implications and Future Directions

• Reliability Diversity: The paper highlights the exploitation of reliability diversity as a principle to manage interference and improve performance trade-offs. The different reliability requirements and definitions across services are thus harnessed for optimized non-orthogonal slicing.
• Future Developments: Future research could expand on the integration of diverse arrival processes, frequency/time resource allocations, and more dynamic network scenarios. Additionally, extending the model to multi-cell configurations and incorporating realistic mobility patterns could yield further insights.

In conclusion, the paper offers a robust theoretical framework for evaluating the efficiency and practicality of network slicing strategies in 5G systems. It balances service requirements through tailored resource allocation while probing into the potential advantages of non-orthogonal sharing amidst growing network heterogeneity.