Different modulation methods corresponding to different transmitting abilities in air interface. R99/R4: QPSK HSDPA: QPSK or 16QAM The UTRAN air interface uses QPSK modulation in the downlink, although HSDPA may
Tag Archives: amplitude
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).
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
The 3G LTE uses 3 Quadrature Amplitude Modulations (QAMs) depending on the radio quality. QAM uses both the amplitude and the phase. The LTE supports in DL and UL the
SC-FDMA utilizes single carrier modulation, DFT-spread orthogonal frequency multiplexing, and frequency domain equalization. LTE uses OFDMA on the DL. It allocates DL bandwidth to the user based on resource blocks,
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