HOW IS DOWNLINK POWER CONTROL USED IN LTE?
The simple answer is, there is no power control in the downlink for LTE. However, power control or power boosting can be applied on both data and control channels of LTE in the downlink. The downlink data channel of LTE is PDSCH and the downlink control channels of LTE are: PBCH PDCCH PCFICH PHICH Data […]
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WHY IS BLINDING DECODING USED FOR PDCCH ?
Each PDCCH supports multiple formats and the format used is usually unknown to the UE. Therefore, the terminal needs to blindly detect the format of the PDCCHs by decoding each format individually. Well, that may be okay for smaller bandwidth scenarios such as 1.4 MHz, 3 MHz etc. However, with bigger bandwidth markets such as […]
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WHAT IS THE PROCEDURE FOR DOWNLINK L1/L2 CONTROL SIGNALLING IN LTE?
Downlink Layer 1 / Layer 2 (L1/L2) control signaling is used for transmitting downlink scheduling assignments required for the terminal to properly receive, demodulate and decode the DL-SCH channel. The uplink scheduling grants informing the terminal about resources and transport format for UL-SCH transmission, and hybrid-ARQ (HARQ) acknowledgements in response to UL-SCH transmission also arrive […]
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WHAT REFERENCE SIGNALS ARE DEFINED FOR LTE DOWNLINK TRANSMISSION?
The downlink reference signals consist of so-called reference symbols which are known symbols inserted within the OFDM time/frequency grid. These reference signals can be used by the UE for downlink channel estimation to enable coherent detection. For LTE Downlink, three types of reference signals are defined:Up to four cell-specific reference signals, each corresponding to one downlink […]
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WHAT IS THE DIFFERENCE BETWEEN NORMAL AND EXTENDED CYCLIC PREFIX IN LTE DOWNLINK TRANSMISSION?
In order to answer this question, take a look at the figure below. The figure below outlines the more detailed time-domain structure for LTE downlink transmission for each slot of length. Tslot = 0.5 ms consists of a number of OFDM symbols. A sub-carrier spacing f = 15 kHz corresponds to a useful symbol time Tu = 1/ f ≈ […]
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