Tag: modulation

Constellation in LTE In LTE (Long-Term Evolution), the term “constellation” typically refers to the modulation scheme used for transmitting data over the air interface. LTE uses Quadrature Amplitude Modulation (QAM)…

Processing Procedure of WCDMA System Source coding can increase the transmitting efficiency. Channel coding can make the transmission more reliable. Spreading can increase the capability of overcoming interference. Through the…

Message Transmission Mode MS measures the frame quality and informs the base station to the result i.e. whether it is in the threshold or periodical  mode. Base station determines whether …

     In an actual application, the system implements the modulation in this way:  as shown above, I and Q channel sequences in the figure represent two channels of cyclic PN…

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…

A data-modulation scheme defines how the data bits are mixed with the carrier signal, which is always a sine wave. There are three basic ways to modulate a carrier signal…

Transmitting:  The process is similar to that of BS. The frequency offset is pre-corrected. The Ranging and BW Request are generated at the physical layer and a code is selected…

Transmitting:  After being processed at the MAC layer, the downlink data is sent to the physical layer inthe format of MAC PDU. The MAC PDU arranges the data block size…

Reverse power control Open loop power control Closed loop power control Inner loop power control:  800 Hz Outer loop power control Forward power control Message transmission mode: threshold transmission periodic…

The long code is a PN sequence with period of 242-1chips The functions of a long code: Scramble the forward CDMA channel Control the insertion of power control bit Spread…