Frequency separation class separation (Fs) 800 MHz 1200 MHz 1400 MHz 1000 MHz 1600 MHz 1800 MHz 2000 MHz 2200 MHz 2400 MHz Table 5.10. Maximum spacing of CC radio channels 5.3. Supplementary UpLink (SUL) Carrier aggregation increases radio data rates by adding the bandwidth of each CC radio channel. In the case of SUL mode, the mobile terminal has an additional uplink band, but uplink transmission can only take place in one band, either the traditional paired band or the SUL band. The SUL bandwidth is generally smaller than the traditional band, but the carrier frequency is lower, thereby improving cell coverage for the uplink. The SUL bandwidth can be automatically adapted by the radio node if the latter manages the DSS mode with a sharing of the 4G/5G band. 5G-NR Radio Interface - Operations on the Frequency Bands DL 3500 MHz UL 700 MHz Uplink coverage 3.5 GHz Downlink coverage 3.5 GHz Uplink coverage 700 MHz Figure 5.5. SUL mode. For a color version of this figure, see www.iste.co.uk/launay/5g.zip 5.4. Synchronization on the secondary cell 5.4.1. Carrier aggregation procedure 5.4.1.1. The activation and deactivation of the secondary cell Connection establishment is triggered by the mobile to the primary cell (PCell). The PCell supports: - random access and RRC (Radio Resource Control) connection mechanisms; - NAS (Non-Access Stratum) messages relating to mobility management and session management. The other radio channels are called SCell (Secondary Cell). The secondary cells only transmit IP packets of the traffic plane. The aggregation can associate radio channels operating in TDD and FDD modes depending on the capabilities of the mobile UE regarding: - the combination list of the aggregated bands BandCombinationList; - the bandwidth classes of the CA-BandwidthClassNR carrier aggregation; - CA-ParameterNR carrier aggregation parameters. NG-RAN and 5G-NR The parameters concerning the aggregation of carriers allow us to specify whether the mobile supports additional or optional features such as: - the configur