Duplexer


The duplexer incorporates the receiver multicoupler system and the transmitter combiner system to a common antenna. Duplexers are especially useful in a microcell application where space is limited, costs are kept to a minimum, and the building owner or manager places limits on the number of antennas allowed in the building.

The types of duplexing that can be used in a wireless system are:

· Separate TX antenna, or no duplexing
· Single, or one antenna
· Double, or two antenna

When no duplexing is used, three separate antennas are connected, on for transmit and two for receiver. This configuration results in lower output power.

In single duplexing, one antenna is used for transmit and receive. A second receive antenna could be connected for receiver diversity. This configuration allows a single antenna to be used but also results in lower output power.


In double duplexing, two antennas are used for both TX and RX and results in the maximum possible output power.

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. 

Cell Reference Symbol Power Configuration

The Adjustable Cell Reference Symbol (CRS) Power feature (FAJ 121 3049) was introduced in L14A. This feature enables flexible setting of the CRS power (Pa) and also enables flexible setting of the type-B resource element power (PDSCH).
The feature improved flexibility for tuning and optimization of downlink resource element power allocation and can lead to improved DL throughput, such as in high dense networks.




The feature controls two factors:
• CRS Power Boost setting (Pa) in the range +3dB to -3dB, previously this value had been fixed by system constant to +3dB.
• Type-B resource element boosting (Pb/Pa) in the range {5/4, 1, 3/4, 1/2}, previously this value had been fixed by a system constant to 1.