  With increasing availability of spectrum in the market due to new spectrum
allocation and re-farming bands from previous cellular generation networks, a
more flexible, efficient and green usage of the spectrum becomes an important
topic in 5G-Advanced. In this article, we provide an overview on the 3rd
Generation Partnership Project (3GPP) work on flexible spectrum orchestration
for carrier aggregation (CA). The configuration settings, requirements and
potential specification impacts are analyzed. Some involved Release 18
techniques, such as multi-cell scheduling, transmitter switching and network
energy saving, are also presented. Evaluation results show that clear
performance gain can be achieved by these techniques.
