OFDM (20141213), the key technology of LTE for wireless communication network learning

The LTE network has several key technologies, namely: Ofdm,amc,harq,mimo,icic,son

Today first to understand OFDM; (orthogonal Frequency Division multiplexing) Orthogonal frequency Division Multiplexing

The channel is divided into multiple orthogonal sub-channels, the high-speed data signal is converted into parallel low-speed sub-data stream, and modulated to each sub-channel for transmission.

Orthogonal Frequency Division Multiplexing (OFDM) system is a multi-carrier transmission system which is developed by the discrete Fourier transform (DFT) and fast Fourier method (FFT).

After understanding the above definitions, we will then use several graphs to understand orthogonal frequency division multiplexing.

By the inverse Fourier transform (IFFT) The same frequency time phase opposite carrier and cancel out, the same phase will be superimposed at this frequency time, the wave is a valid wave, the information is transmitted through this effective wave,

See below OFDMA (Orthogonal frequency Division multiple Access): Can be considered from three-dimensional thinking, in phase, time, frequency of the three three-dimensional parameter structure to see OFDMA.

The effective wave of orthogonal post data, transverse is frequency, sub-carrier interval 15K, longitudinal axis is time, 1ms Dispatch once, the CP is inserted between each layer wave to reduce ISI (inter-symbol interference).

For the Fourier transform those algorithms, do not go into the deep, I believe that you also have a certain understanding of OFDM,OFDMA, tomorrow we continue to explore other key technologies.

Taking a piece from: http://wenku.baidu.com/view/eafe64be6294dd88d0d26b86.html

http://www.mscbsc.com/bbs/viewthread.php?tid=562499

OFDM (20141213), the key technology of LTE for wireless communication network learning