
16
Power effiCienCy in wireless CommuniCations
en, D
i
, (i = 1, 2, …, N) in Equation (2.1) is given to the modulation
block where in-phase and in-quadrature (I and Q) constellations are
generated. Here, quadrature phase-shift keying (QPSK) is used to map
two bit symbols into the constellations, X
i
, as shown in Figure2.4.
X
1
= 1 + 0 j
X
2
= 0 + 1 j
X
3
= (–1) + 0 j (2.2)
X
4
= 0 + (–1) j
…
After the modulation, the signal is introduced to the IFFT block.
e IFFT block takes frequency domain data and generates corre-
sponding time domain samples (Brooks et al., 2001; Roca, 2007).
ese samples and their adjacent samples are orthogonal to each ...