The 5G NR physical layer

Discussion in '5G' started by Wireless Via, Aug 5, 2017.

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  1. Wireless Via

    Wireless Via Administrator Staff Member

    5G New Radio Physical Layer : The 5G NR physical layer
    Future networks will have to provide broadband access wherever needed and support a diverse range of services including everything from robotic surgery to virtual reality classrooms and self-driving cars.
    5G New Radio is designed to fit these requirements, with physical layer components that are flexible, ultra-lean and forward-compatible.
    5G wireless access is being developed with three broad use case families in mind:
    1. enhanced mobile broadband (eMBB)
    2. massive machine-type communications (mMTC)
    3. ultra-reliable lowlatency communications (URLLC)
    5G NR will operate in the frequency range from below 1GHz to 100GHz with different deployments.

    There will typically be more coverage per base station (macro sites) at lower carrier frequencies, and a limited coverage area per base station (micro and pico sites) at higher carrier frequencies.

    5G vision_use cases, spectrum and deployments.jpg

    The standardisation of NR started in 3GPP in April 2016, with the aim of making it commercially available before 2020.

    NR physical layer design:
    LTE supports the QPSK, 16QAM, 64QAM and 256QAM modulation formats, and all of these will also be supported by NR.
    In addition, 3GPP has included ะป/2-BPSK in UL to enable a further reduced peak-to-average power ratio and enhanced power-amplifier efficiency at lower data rates, which is important for mMTC services.
    For example, 1024QAM may become part of the NR specification.
    Different modulation schemes for different UE categories may also be included in the NR specification.

    Waveform
    3GPP has agreed to adopt CP-OFDM with a scalable numerology (subcarrier spacing, cyclic prefix) in both UL and DL up to at least 52.6GHz.

    Frame structure
    NR frame structure supports TDD and FDD transmissions and operation in both licensed and unlicensed spectrum.
    It enables very low latency, fast HARQ acknowledgements, dynamic TDD, coexistence with LTE and transmissions of variable length (for example, short duration for URLLC and long duration for eMBB).

    Reference signals
    NR has an ultra-lean design that minimizes always-on transmissions to enhance network energy efficiency and ensure forward compatibility. In contrast to the setup in LTE, the reference signals in NR are transmitted only when necessary.

    Multi-antenna transmissions
    NR will employ different antenna solutions and techniques depending on which part of the spectrum is used for its operation. For lower frequencies, a low to moderate number of active antennas (up to around 32 transmitter chains) is assumed and FDD operation is common

    Channel coding
    NR employs low-density parity-check (LDPC) codes for the data channel and polar codes for the control channel. LDPC codes are defined by their parity-check matrices, with each column representing a coded bit, and each row representing a parity-check equation.

    Conclusion
    Flexibility, ultra-lean design and forward compatibility are the pillars on which all the 5G NR physical layer technology components (modulation schemes, waveform, frame structure, reference signals, multi-antenna transmission and channel coding) are being designed and built. The high level of flexibility and scalability in 5G NR will enable it to meet the requirements of diverse use cases, including a wide range of carrier frequencies and deployment options. Its built-in forward compatibility will ensure that 5G NR can easily evolve to support any unforeseen requirements.
     
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