Study on scheduling enhancements with carrier aggregation for UMTS
Data scheduling on multi-carrier has been deployed to achieve higher data rates and load balancing. With the introduction of intra/inter-band features like DC-HSPA/DB-DC-HSPA, data can be scheduled over two carriers in the same band or in different bands. Along with the trend that the basic frequency for MBB coverage is a lower band, e.g. 900MHz, carrier aggregation of two carriers in a lower band and a higher band (cross band carrier aggregation), would become a typical deployment scenario for multi-carrier application.
In cross band carrier aggregation, the reliability of scheduling channels as HS-SCCH or E-AGCH, on the higher and lower frequency carriers is not the same. Assuming the primary carrier is the lower band, the scheduling channels on the secondary carrier are not as reliable as the ones on the primary carrier due to the higher path loss in the higher band.
Assuming scenarios where the secondary carrier operates in the higher frequency, in order to improve the performance of cross band carrier aggregation, the reliability of scheduling channels over the secondary carrier using the higher band should be investigated.