All posts by Azar
HOW IS SC-FDMA SIGNAL GENERATED IN LTE? HOW IS UPLINK SIGNAL GENERATED?
LTE uplink transmission is based on Discrete Fourier Transform (DFT) – spread OFDM (DFTS-OFDM). It is also often referred to as Single-Carrier FDMA (SC-FDMA). Figure above shows the basic structure of DFTS-OFDM modulation with a size-M DFT being applied to the block of M modulation symbols. The output of the DFT is then mapped to […]
I Want to Read More
HOW DOES PAGING WORK IN LTE?
This question can take full pages and pages of discussion, or it can also take a brief discussion to answer, depending on how much depth the interviewer or client is asking for. I will explain paging briefly here. Paging is used for network-initiated connection setup. An efficient paging procedure should allow the UE to sleep […]
I Want to Read More
HOW IS LINK ADAPTATION USED IN LTE DOWNLINK ?
For unicast traffic, link adaptation is used and is controlled by the eNodeB. A common modulation and channel code is used in the frequency domain per UE and codeword. The modulation and coding scheme (MCS) is selected based on Channel Quality Indicator (CQI) feedback and buffer content. Rapid interference variations make it difficult to predict […]
I Want to Read More
WHAT IS LINK ADAPTION?
Link Adaptation is about improving modulation and coding scheme (MCS) to reach users in a better way in terms of throughput and data rate, wherever they are standing within the cell coverage. Even if they are standing closer to the cell edge or farther from the cell, eNodeB scheduler will adjust its modulation scheme and/or […]
I Want to Read More
HOW IS POWER CONTROL USED IN LTE UPLINK TRANSMISSION?
Uplink power control is used both on the PUSCH and on the PUCCH channels. In both cases, a parameterized open loop combined with a closed loop mechanism is used. Roughly explained, the open loop part is used to set a point of operation, around which the closed loop component operates. Different parameters (targets and ‘partial […]
I Want to Read More