In the USA the lower 700 MHz band is licensed in 6 MHz blocks. The lower 700 MHz A block covers 698-704 MHz UL and 728-734 MHz in the downlink. NR band n12 covered all but the lowest 1 MHz of the A block. NR band n85 covers the entire A Block. Hence, NR band n85 extends 1 MHz lower than NR band n12. Because some devices will support n12 while others will support n85, it would be beneficial if n12 capable UEs could use the 5 MHz at the bottom of n12 downlink while n85 capable UEs are able to use the 6 MHz at the bottom of the n85 downlink.

One way to allow n12 UEs to use 729-234 MHz DL and n85 UEs to use 728-734 MHz DL would be to use the next wider channel bandwidth approach. The network could configure an n85 cell with a downlink of 729-234 MHz and include n12 in the MultiFrequencyBandListNR in the SIB. Then both n12 capable and n85 capable UEs could access the cell. After the gNB processes the UE capabilities, the network could assign n85 capable UEs a UE-Specific downlink channel bandwidth covering 728-738 MHz. Based on feedback from RAN2 in R4-2200031 signalling supports the configuration of a channel that is larger than the channel bandwidth in the SIB and/or extends beyond the edge of the channel in the SIB as long as it is within the band. However, since this behavior might not be supported by all UEs, new capability signalling may be required to enable the n85 capable UE to indicate that it supports such a configuration. Also, because the uplink configuration would be 5 MHz, the n85 UEs would also need to indicate support to an asymmetric channel bandwidth.

One way to allow n12 UEs to use 729-234 MHz DL and n85 UEs to use 728-734 MHz DL would be to use one of the overlapping channel bandwidth approaches. The network could configure an n85 cell with a downlink of 729-234 MHz and include n12 in the MultiFrequencyBandListNR in the SIB. Then both n12 capable and n85 capable UEs could access the cell. After the gNB processes the UE capabilities, the network could configure n85 capable UEs with one of the overlapping channel bandwidth approaches using the 5 MHz at the bottom of n85 (728-733 MHz) and the next 5 MHz (739-734 MHz). Legacy UEs would only use 729-234 MHz.