5G NR LTE Air Interface

The 5G NR (New Radio) Air Interface

5G New Radio (5G NR), standardised by 3GPP, is the air interface designed for 5G networks, built from the ground up to support diverse services, devices, and deployment scenarios. Unlike previous generations, 5G NR addresses enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC). It operates across a wide range of spectrum bands, including sub-6 GHz and mmWave (24–71 GHz), and integrates with LTE for backward compatibility while introducing forward-compatible features for future evolution. 5G NR is widely deployed, supporting applications like autonomous vehicles, smart cities, AR/VR, and massive IoT.

5G NR Air Interface for LTE
5G NR Air Interface for LTE

5G NR and LTE Integration

5G NR enhances and coexists with LTE, leveraging LTE-Advanced and LTE-Advanced Pro (Releases 10–15) as a foundation. Key integration aspects include:

  • Non-Standalone (NSA) 5G NR: Finalised in December 2017 (Release 15), NSA 5G NR uses LTE for control signalling and the existing LTE core network (EPC), with 5G NR for high-speed data. The first NSA 5G NR call was completed in February 2018 by Vodafone and Huawei in Spain.

  • Standalone (SA) 5G NR: Completed in June 2018 (Release 15), SA 5G NR operates independently with a new 5G core (5GC), offering full capabilities like network slicing and URLLC. SA deployments are prevalent, enabling advanced use cases.

  • Dual Connectivity: Supports simultaneous LTE (sub-6 GHz) and 5G NR (sub-6 GHz or mmWave) connections, with user-plane aggregation for seamless data delivery.

  • Dynamic Spectrum Sharing (DSS): Allows LTE and 5G NR to share the same spectrum band, facilitating smooth transitions for operators.

What 5G NR Does

5G NR significantly improves performance, flexibility, scalability, and efficiency over LTE, maximising spectrum utilisation across licensed, shared, and unlicensed bands. Key objectives include:

  • Diverse Services: Supports eMBB for high-bandwidth applications (e.g. 4K/8K streaming, AR/VR), URLLC for latency-sensitive use cases (e.g. autonomous driving), and mMTC for massive IoT deployments (e.g. smart cities).

  • Deployment Flexibility: Supports macro cells, small cells, and hotspots, with scalability for urban, suburban, and rural environments.

  • Device Connectivity: Enables device-to-device (D2D) communications, sidelink, and multi-hop mesh for extended coverage.

  • Efficiency: Achieves unprecedented cost, power, and deployment efficiencies, with energy-efficient designs for devices and networks.

How 5G NR Works

5G NR’s design incorporates three foundational elements:

Optimised OFDM-Based Waveforms and Multiple Access

  • Waveform: Uses Cyclic Prefix Orthogonal Frequency-Division Multiplexing (CP-OFDM) for both uplink and downlink, with Discrete Fourier Transform-spread OFDM (DFT-s-OFDM) as an optional uplink waveform for coverage-limited scenarios.

  • Flexible Numerology: Supports scalable subcarrier spacing (15 kHz to 240 kHz), enabling low-latency and high-throughput configurations tailored to use cases.

  • Benefits: Optimises performance across diverse spectrum bands (sub-1 GHz to 71 GHz), supports mixed numerologies for multiplexing eMBB, URLLC, and mMTC, and ensures compatibility with LTE and WiFi.

Common Flexible Framework

  • Multiplexing: Enables efficient multiplexing of diverse services (eMBB, URLLC, mMTC) through flexible frame structures and dynamic resource allocation.

  • Low Latency: Achieves 1 ms or lower air interface latency via mini-slots and grant-free uplink transmission.

  • Forward Compatibility: Designed to support future services, ensuring longevity through Release 18 (2024) and beyond.

Advanced Wireless Technologies

5G NR leverages advanced technologies for its three service categories:

  • Enhanced Mobile Broadband (eMBB):

    • Massive MIMO: Uses up to 64 antenna ports for beamforming and spatial multiplexing, increasing capacity and coverage.

    • mmWave: Operates in 24–71 GHz bands for multi-Gbps speeds in dense areas.

    • Advanced Channel Coding: Employs Low-Density Parity-Check (LDPC) for data channels and Polar codes for control channels, improving efficiency.

    • Spectrum Sharing: Supports DSS and NR-U for licensed and unlicensed spectrum.

  • Ultra-Reliable Low-Latency Communications (URLLC):

    • Low Latency: Achieves 0.5-1 ms latency with mini-slots and prioritised scheduling.

    • High Reliability: Ensures 99.9999% packet delivery for applications like C-V2X, drone control, and industrial automation.

    • Technologies: Includes redundant links, multi-connectivity, and grant-free uplink for no-failure scenarios.

  • Massive Machine-Type Communications (mMTC):

    • NB-IoT and LTE-M Enhancements: Supports low-power, low-data-rate devices with extended coverage and voice support (Release 13–15).

    • RedCap Devices: Introduced in Release 17 for mid-tier IoT with reduced complexity.

    • Multi-Hop Mesh: Extends coverage for IoT devices via WAN-managed architectures.

    • Efficient Uplink: Uses Resource Spread Multiple Access (RSMA) for scalable IoT uplink.

Industry Involvement

The 5G NR ecosystem involves major players like Qualcomm, Ericsson, Nokia, Huawei, Intel, and operators such as AT&T, Vodafone, China Mobile, and BT/EE. Key contributions include:

  • Qualcomm: Pioneered 5G NR with the Snapdragon X50 modem (2016), supporting sub-6 GHz and mmWave. By 2025, the Snapdragon X75 supports Release 18 features, including AI-driven optimizations. Qualcomm conducted trials with AT&T, Vodafone, and others, and completed NSA 5G NR testing with Nokia (2018) and ZTE/China Mobile (2017).

  • Ericsson: Launched the AIR 6468 (2016) and AIR 3246 (2018) for 5G NR, supporting FDD and TDD. Conducted SA 5G NR trials with Vodafone and King’s College London (2017).

  • Nokia: Deployed the AirScale base station (2017), supporting over 100 operators by 2025. Collaborated with Qualcomm on NSA 5G NR testing (2018).

  • Huawei: Introduced the Balong 5G01 chipset and 5G NR terminals (2018). Completed interoperability testing with Intel and China Mobile (2018).

  • Intel: Developed the XMM 8000 series for 5G NR, enabling commercial devices by 2019.

  • Operators: BT/EE tested end-to-end 5G NR in the UK (2017), while Vodafone, Deutsche Telekom, and KT Corporation conducted trials in 2018–2019.

Over 50 companies now collaborate on 5G NR, with commercial deployments in over 100 countries, supported by CableFree’s 5G NR Base Station and CPE products compliant with Release 18.

For Further Information

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