LTE Advanced: 3GPP Solution for IMT-Advanced

12.5 Carrier Aggregation Enhancements

Following the introduction of the carrier aggregation in Release 10, the work item [7] was set up to address improvements for the carrier aggregation operation. As part of the work item, the following new items were worked to be part of Release 11, explained in more detail later in this section:

• Support of multiple uplink timing advance values;
• Intra-band non-contiguous carrier aggregation;
• Support of inter-band carrier aggregation for TDD DL and UL including different uplink-downlink configurations on different bands;
• New carrier type (this to be completed in Release 12 only).

The support of multiple uplink timing advance values is motivated to enable operation in such a scenario where band specific repeaters are in use, as discussed in Chapter 5. If the repeater is available only on one of the bands, the resulting uplink propagation time is different between different frequency bands due to the internal delay of the repeater and thus a single timing advance value is not sufficient with the use of two uplinks. The MAC layer signaling in Release 11 will allow the eNodeB to provide the UE timing advance values specific for each uplink band..

As part of the Release 11 work is also the framework for intra-band non-contiguous carrier aggregation operation. With the intra-band non-contiguous operation there can be another operator or system operating in between the carriers thus the devices must have enough protection to cover such case with up ...