5G NR has an ultra lean design, which minimizes always-on transmissions to enhance network energy efficiency, reduce interference, and ensure forward compatibility. In contrast to the setup in LTE, the reference signals in NR are transmitted only when necessary.
NR downlink reference signals are used for specific roles and can be flexibly adapted for different deployment scenarios and spectrum
4G on the other hand ha has a only one type of reference signal design a ‘one size fits all’ downlink reference signal design callled CRS [CRS: Cell-Specific RS]
This configuration has different drawbacks as:
It Limits flexible network deployments, it is not network energy efficient, it is not applicable for higher spectrum (>6GHz), it is not MIMO friendly for large number of antennas and not suitable for 5G new radio
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