MPSK Modulator Baseband
Modulate using Mary phase shift keying
Libraries:
Communications Toolbox /
Modulation /
Digital Baseband Modulation /
PSK
Communications Toolbox HDL Support /
Modulation /
PM
Description
The MPSK Modulator Baseband block modulates an input signal using Mary phase shift keying (PSK) and returns a complex baseband output. The modulation order, M, which is equivalent to the number of points in the signal constellation, is determined by the Mary number parameter. The block accepts scalar or column vector input signals.
Examples
Ports
Input
Output
Parameters
Block Characteristics
Data Types 

Multidimensional Signals 

VariableSize Signals 

^{a} ufix(1) at the input if ''input type'' is set to ''bit''. ufix(ceil(log2(M))) at input if ''input type'' is set to ''integer'' for Mary modulation. ^{b} Fixedpoint outputs must be signed. 
More About
Algorithms
For higherorder PSK constellations, the complex baseband form for an Mary PSK signal using binaryordered symbol mapping is
$${s}_{m}(t)=\mathrm{exp}\left(j\left(\frac{2\pi m}{M}+\varphi \right)\right);\text{\hspace{1em}}m\in \{0,1,\dots ,M1\}.$$
When the input is configured for bits, groups of log_{2}(M) bits represent the complex symbols for the configured symbol mapping. The mapping can be binary encoded, Gray encoded, or custom encoded.
Gray coding has the advantage that only one bit changes between adjacent constellation points, which results in better bit error rate performance.
This 8PSK constellation uses Graycoded symbol mapping.
For modulation orders beyond 4, the bit error rate performance of PSK in AWGN worsens. In this bit error rate plot for Graycoded mapping, the QPSK and BPSK curves overlap one another.
References
[1] Proakis, John G. Digital Communications. 4th ed. New York: McGraw Hill, 2001.
Extended Capabilities
Version History
Introduced before R2006a