Tag: lte

The state-of-the-art design of the LTE air interface is characterised by OFDMA (DL) and SC-FDMA (UL) together with MIMO. The downlink modulation is based on OFDMA (Orthogonal Frequency Division Multiple…

The guard period after each rectangular pulse carrying the modulated data symbol is a simple and efficient method to deal with multi-path reception. The cyclic prefix (CP) simply consists of…

The receiver is like in any other radio system the more complicated part. In radio systems and of course also OFDM there are two special points a receiver has to…

A typical OFDM transmitter is shown on the following figure. To reduce the amount of RF hardware required for OFDM the modulation process is split into two parts. A first…

FDM in LTE Conventional multi-carrier operation as it is used for FDM works simply by selecting a number of center frequencies – one for each carrier to be used. The…

RF engineering is a trade off between: required radio spectrum (bandwidth), speed of data transmission (bit rates) and complexity of implementation. The pulse form used to modulate complex data symbols…

The 3G LTE uses 3 Quadrature Amplitude Modulations (QAMs) depending on the radio quality. QAM uses both the amplitude and the phase. LTE devices use QPSK, 16QAM and 64QAM to…

  If the voice signal is modulated and transmitted directly after channel coding, due to the condition changes in mobile communication channel, a deep of the fading will influence a…

The Logical  Channel is used in time multiplex in a physical channel, which is categorized according to the types of messages transmitted in the physical channel. Different logical channels are…

Eps bearer LTE EPS is a connection-oriented transmission network and, as such, it requires the establishment of a “virtual” connection between two endpoints (e.g. a UE and a PDN-GW) This…