Why Different Numerology in 5G?

Introduction

5G wireless technology represents a major advancement in mobile networks, promising faster speeds, lower latency, and the ability to connect massive numbers of devices.

One key technical aspect of 5G is the use of different numerologies – essentially, the parameters that define the spacing and structure of the 5G signal. In this post, we’ll explore what numerology is, why multiple numerologies are used in 5G, and the benefits this provides.

What is Numerology in 5G?

In simple terms, numerology refers to the transmission properties of the 5G signal, including things like:

  • Subcarrier spacing – The distance between adjacent subcarriers or tones that carry data. Wider spacing provides more robustness, narrower spacing allows more data capacity.
  • Symbol length – The amount of time used to transmit a data symbol. Shorter lengths decrease latency, longer lengths improve performance at high speeds.
  • Cyclic prefix length – A portion of each symbol that is repeated to mitigate interference.

Together, these parameters define the basic structure and timing of the 5G waveform. Different combinations of numerology parameters allow optimization for different usage scenarios.

Why Are Multiple Numerologies Used?

Previous wireless generations like 4G have used a single numerology. However, 5G supports multiple configurable numerologies for several important reasons:

Support Diverse Services

5G aims to enable a wide range of use cases, from IoT sensors to high-speed mobile broadband. Each of these services has different requirements – for example, ultra-reliable low latency communication for industrial automation versus best-effort mobile video streaming. Multiple numerologies allow the optimal parameters to be configured based on the service needs.

Improve Spectral Efficiency

With a single numerology, resources would be wasted when parameters offer more than needed. Dynamic numerologies allow precisely configuring OFDM parameters to match the target application, improving spectral efficiency.

Simplify Coexistence

5G is designed to coexist and interwork with 4G LTE. Using flexible numerologies simplifies managing coexistence between different wireless technologies.

Key Benefits of Multiple Numerologies

The use of multiple numerologies is a major innovation in 5G that provides several key advantages:

  • Flexible optimization – Services get exactly the resources and parameters needed, no more, no less.
  • Efficient spectrum utilization – Precisely configuring parameters maximizes use of available spectrum.
  • Support for diverse verticals – Enables tailoring 5G to meet unique performance needs.
  • Simplified coexistence – Managing interaction between 4G, 5G, and Wi-Fi is easier with adjustable numerologies.
  • Future-proofing – Adding new numerologies in the future can support new services and use cases.

Conclusion

Multiple numerologies represent a fundamental 5G innovation that brings significant gains in flexibility, efficiency, and performance. By tuning the signal parameters to precisely match service requirements, 5G makes the best use of spectrum while supporting the needs of diverse applications. The use of scalable numerology options helps ensure 5G networks can meet current and future demands.

References

  • R1-1710818, 3GPP TSG RAN WG1 Meeting #89, “R1-1710818: On NR numerology and frame structure”.
  • “Making 5G NR a Reality”, Qualcomm whitepaper, 2016.
  • “5G Wireless Communication Systems: Vision, Architecture, and Challenges”, Saad Asif, 2018.

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