In this letter, we introduce direct-current (DC) offset hybrid frequency and phase-shift keying (DC-FPSK) modulation for Internet-of-Things based on optical wireless systems. For DC-FPSK, non-negative phase-modulated frequency waveforms are generated by combining frequency-shift keying (FSK), phase-shift keying (PSK) and a DC offset. We propose optimal maximum likelihood and sub-optimal receivers for DC-FPSK. The performance is appraised in terms of Euclidean distance, bit-error-rate (BER) performance and energy efficiency. We determine that combining 4-PSK with conventional DC-FSK is the optimal approach to enhance the energy and spectral efficiencies.

中文翻译：

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用于节能光无线系统的混合频率和相移键控调制

在这封信中，我们介绍了用于基于光无线系统的物联网的直流 (DC) 偏置混合频率和相移键控 (DC-FPSK) 调制。对于 DC-FPSK，非负相位调制频率波形是通过组合频移键控 (FSK)、相移键控 (PSK) 和 DC 偏移生成的。我们为 DC-FPSK 提出了最优最大似然和次优接收器。性能根据欧几里德距离、误码率 (BER) 性能和能效进行评估。我们确定将 4-PSK 与传统 DC-FSK 相结合是提高能量和频谱效率的最佳方法。