OFDM implementation in Detail

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…

Difference Between OFDM and FDM in LTE

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…

Orthogonal Code Usage – Coding & Decoding in WCDMA

How Orthogonal Code works in WCDMA? 1.Coding By spreading, each symbol is multiplied with all the chips in the orthogonal sequence assigned to the user. The resulting sequence is processed…

System information & DL-SCH data in LTE

System information 1920 bits or 1728 bits are to be transmitted for normal or extended CP resp.. The PBCH is transmitted every 40 ms. The bit scrambling depends on the…

OFDMA Parameter for LTE

How Many OFDMA Parameter for LTE? Which is OFDMA Parameter for LTE ? The width of a Sub-carrier is 15 kHz whatever the bandwidth The bandwidths are: 1.4, 3, 5,…

Inter-Symbol Interference in LTE

What is the multipath? Due to the signal propagation phenomena, like reflection or diffraction, a receiver can receive several delayed versions of the same signal. This creates Inter-Symbol Interference (ISI).…

Constellation in LTE

The QPSK is the most robust modulation. It can be represented by a constellation: The radius, R, represents the amplitude. The angle, ?, represents the phase. There are 1 amplitude…

Ways to transmit training symbols: preamble or pilot tones in Wimax

There are two ways to transmit training symbols: preamble or pilot tones. Preambles entail sending a certain number of training symbols prior to the user data symbols. In the case…

What is SC-FDMA and how it works in LTE?

One of the major drawbacks of an OFDMA system is, that the transformation of a complex symbol mapped sequence (e.g. BPSK, QPSK, etc.) onto a small set of subcarriers produces…

Pulse shaping and spectrum in LTE

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…