Power and bandwidth efficient constant-envelope BPSK signals and its continuous phase modulation interpretation

A constant-envelope BPSK signal is realised by specifying the phase transition characteristics of a conventional BPSK signal. The CE-BPSK signal achieves greater power and bandwidth efficiency than a conventional square-root raised-cosine (SRRC) filtered BPSK signal, while still having backward compatibility with the conventional BPSK signal. Utilising the constant-envelope and continuous phase characteristics, it is shown that the CE-BPSK is a kind of continuous phase modulation. This allows the CE-BPSK signal to be generated in existing FM-based transmitter systems. The power spectral density and eye-diagram of the continuous phase modulated CE-BPSK signal are identical to those of the I/Q modulated CE-BPSK signal. It is shown that the bandwidth efficiency of the CE-BPSK signal is ten times greater than the SRRC-filtered BPSK signal in a switching amplification environment. It is also shown that the bit error rate performance of the CE-BPSK signal is better than that of the SRRC-filtered BPSK signal by 0.7 dB at a BER of 10−4 in the switching amplification environment.