Common Channel Configuration in LTE

Common Channel Configuration

Uplink resource blocks are required to be allocated for uplink control signaling (PUCCH). The number of RBs will be dependent on bandwidth and loading.

Downlink resources are also allocated for downlink control signaling on the PDCCH channel. This is specified as the number of OFDM symbols (Control Format Indicator).

PDCCH and PUCCH allocations will have an impact on peak data throughputs and system capacity. The PDCCH power boost feature makes it possible to adjust the power of the PDCCH to match the actual number of needed Control Channel Element (CCE) resources. Use cases include beam forming coverage extension, range extensions for small cells and general increase of the PDCCH capacity, which is useful for e.g. VoLTE applications. The maximum power increase is 6 dB.

The feature can be used in conjunction with the Enhanced PDCCH Link Adaptation feature which can provide significantly increased PDCCH capacity, as the RBS better determines the number of CCEs to utilize for UEs, independently from PDSCH.

The Enhanced PDCCH Link Adaptation feature introduces a dedicated link adaptation capability for PDCCH. This allows the eNB to control the number of CCEs to be used in PDCCH allocations to be optimized for a specific PDCCH BLER target, rather than using a fixed offset from the PDSCH link adaptation. It is expected that this will significantly increase the number of UEs that can be scheduled per TTI, as it relates to PDCCH usage.