Wireless Mantra of the Week: NR Air Interface

Mantra: In 5G, the NR air interface provides superior performance compared to 4G LTE.
Brief Explanation.
The New Radio (NR) air interface includes several enhancements relative to LTE. NR is a beamformed air interface with fewer beams in low frequency bands and more beams at high frequency bands. The flexible NR frame structure supports variable-length slots, symbol-based resource allocation, and a self-contained slot. Different OFDM numerologies (i.e., different subcarrier spacings and Cyclic Prefix values) and carrier Bandwidth Parts provide flexibility of supporting different use cases and different spectrum holdings in different geographic areas and simplify UE processing. Advanced channel coding techniques of Low Density Parity Check (LDPC) coding and polar coding improve spectral efficiency and reliability. Advanced MIMO techniques and support for sub-6 GHz and millimeter wave spectrum enable enhanced beamforming (e.g., hybrid beamforming) to improve throughput and simplify implementations. Both downlink and uplink use enhanced OFDM, where the amount of guard band is reduced compared to LTE due to better signal processing. Advanced antenna techniques such as SU-MIMO and MU-MIMO supported in LTE are also supported in 5G with additional performance enhancements and flexibility such as the opportunity to use massive MIMO. The amount of overhead signals is configurable and certain reference signals and system information messages are transmitted only when necessary. Dual connectivity between 5G and LTE is also supported.

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