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(a) Schematic OFDM-PON architecture with delta-sigma modulation, employing binary IM-DD channel, (b) block diagram for the nthorder delta-sigma modulation, (c) signal waveforms before (blue curve) and after (black dot) delta-sigma modulation, (d) responses of noise shaping in delta-sigma modulation with 1st-order, 2nd-order and 4th-order structures, respectively.
Source publication
In this paper, a delta-sigma modulation is proposed to enable transmission of OFDM signals by cost-effective binary IM-DD channels. Compared to traditional OFDM-PON, around 4-dB improvement in receiver sensitivity is achieved with the 20% average EVM.
Contexts in source publication
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... is improved by adding (sigma) the resulting signal. Lastly, a 1-bit quantization is applied to output the binary bit sequence [5]. Although delta-sigma modulation requires higher bandwidth, the binary optics/electronics chips (driver, modulator, etc.) are relatively easy to design. And, there is less requirements on spectrum efficiency in PON. Fig. 1(b) shows the block diagram of delta-sigma modulation, in which the number of cascaded feedback loops indicates the order of delta-sigma modulation. Fig. 1(c) shows the time domain waveforms before and after delta-sigma modulation. The 'blue' curve represents the original OFDM signal, and the 'black' dot represents delta-signal modulated ...
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... modulation requires higher bandwidth, the binary optics/electronics chips (driver, modulator, etc.) are relatively easy to design. And, there is less requirements on spectrum efficiency in PON. Fig. 1(b) shows the block diagram of delta-sigma modulation, in which the number of cascaded feedback loops indicates the order of delta-sigma modulation. Fig. 1(c) shows the time domain waveforms before and after delta-sigma modulation. The 'blue' curve represents the original OFDM signal, and the 'black' dot represents delta-signal modulated bit sequence. The retrieved OFDM signal after LPF is also represented as the 'red' curve in Fig. 1(c). The delta-sigma modulator can be viewed as a noise ...
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... feedback loops indicates the order of delta-sigma modulation. Fig. 1(c) shows the time domain waveforms before and after delta-sigma modulation. The 'blue' curve represents the original OFDM signal, and the 'black' dot represents delta-signal modulated bit sequence. The retrieved OFDM signal after LPF is also represented as the 'red' curve in Fig. 1(c). The delta-sigma modulator can be viewed as a noise shaper that acts like high pass filter (HPF). Fig. 1(d) shows the noise-shaping responses in delta-sigma modulation with 1st, 2nd and 4th-order structures, respectively. The responses are measured at 8-times oversampling ratio (OSR = 8). In Fig. 1(d), 'fb' denotes the bandwidth of ...
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... before and after delta-sigma modulation. The 'blue' curve represents the original OFDM signal, and the 'black' dot represents delta-signal modulated bit sequence. The retrieved OFDM signal after LPF is also represented as the 'red' curve in Fig. 1(c). The delta-sigma modulator can be viewed as a noise shaper that acts like high pass filter (HPF). Fig. 1(d) shows the noise-shaping responses in delta-sigma modulation with 1st, 2nd and 4th-order structures, respectively. The responses are measured at 8-times oversampling ratio (OSR = 8). In Fig. 1(d), 'fb' denotes the bandwidth of signal and the horizontal axis represents the normalized frequency. It can be observed that the 'stop-band' ...
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... LPF is also represented as the 'red' curve in Fig. 1(c). The delta-sigma modulator can be viewed as a noise shaper that acts like high pass filter (HPF). Fig. 1(d) shows the noise-shaping responses in delta-sigma modulation with 1st, 2nd and 4th-order structures, respectively. The responses are measured at 8-times oversampling ratio (OSR = 8). In Fig. 1(d), 'fb' denotes the bandwidth of signal and the horizontal axis represents the normalized frequency. It can be observed that the 'stop-band' response gets much improved in the range of [0, fb] with the 4th-order delta-sigma modulation. Figure 2 shows the experimental setup for the proposed OFDM-PON based on delta-sigma modulation. The ...
