We propose a new continuous phase frequency shift keying that is particularly suited for multi-antenna communications when the link budget is critical and beam alignment is problematic. It combines the constant envelope of frequency modulation with low-rate repetition coding in order to compensate for the absence of transmit beamforming. Although it is a frequency modulation, its transmit signal shows close to rectangular spectral shape. Similar to GSM's Gaussian minimum shift keying, it can be well approximated by linear modulation, when combined with differential precoding. This allows for easy coherent demodulation by means of a windowed fast Fourier transform.

翻译：我们提出一种新型连续相位频移键控调制方式，特别适用于链路预算紧张且波束对准存在困难的多天线通信场景。该方案将频率调制的恒定包络特性与低速率重复编码相结合，以补偿发射波束成形的缺失。尽管属于频率调制，其发射信号频谱形状接近矩形。与GSM中的高斯最小频移键控类似，当结合差分预编码时，该调制可通过线性调制进行良好近似。这使得采用加窗快速傅里叶变换实现易于操作的相干解调成为可能。