5G Release 15 was the first release of 5G and its specification was completed in June 2018. Release 16/17 specifications were drafted as extensions to 5G Release 15 with its RAN technology NR or New Radio. Rel-17 provided support for even higher frequency bands and Non-Terrestrial Network NTN systems and added a low-cost NR device category called Reduced Capability RedCap toward wearable terminals and other devices.
Release 18 and later specifications in which studies and specifications toward further advances in 5G have been progressing are defined as 5GAdvanced.
Some of Release 18 features
- Release 18 specifies that handovers are to be performed on an even lower layer (L1/L2) referred to as Lower layer Triggered Mobility (LTM) besides the conventional L3 handover based on RRC.
- Enhanced MIMO, For Downlink, instead of supporting 8 Layers SU-MIMO and 12 Layers MU-MIMO, In Rel-18, discussions were held on extending the maximum number of layers for MU-MIMO to 24 layers to increase capacity even further.
- Rel-17 specified NTN on the premise of UEs equipped with a GNSS function. Then, to achieve a more practical and efficient NTN, Rel-18 specified functional enhancements including UL coverage improvements to support small-form terminals like smartphones.
- In Rel-18, studies were conducted on new technology areas based on different needs such as the application of AI/ML technologies to the radio interface, duplex extension to the downlink/uplink, and ultra-low-power receivers for reducing terminal power consumption and wake-up signals for such receivers.