Experimental demonstrations of DSP-enabled flexibility, adaptability and elasticity of multi-channel >72Gb/s over 25 km IMDD transmission systems

Abstract

DSP-enabled multi-channel aggregation techniques are promising for cost-effectively improving the flexibility, adaptability and elasticity of fronthaul transport networks. By utilizing orthogonal digital filtering in multi-channel aggregation in IMDD transmission systems, two DSP-enabled matching filter (MF)-free multi-channel aggregation techniques respectively based on SSB OFDM and orthogonal DSB OFDM have been reported; however, the SSB (DSB) technique has a drawback of relatively high digital filter DSP complexity (reduced adaptability to physical layer system characteristics). To effectively overcome these drawbacks associated with these two techniques, in this paper, a DSP-enabled MF-free adaptively variable SSB/DSB OFDM multi-channel aggregation technique is proposed and experimentally demonstrated, in which >72Gb/s@25 km IMDD transmissions have been achieved. This work also evaluates, for the first time, the flexibility, adaptability, and elasticity of the orthogonal digital filtering-enabled multi-channel aggregation techniques. The results show that the proposed technique not only maintains the SSB technique’s excellent adaptability but also possesses the DSB technique’s low digital filter DSP complexity features.

Analyzing Peak-to-Average Power Ratio Characteristics in Multi-Channel Intensity Modulation and Direct Detection Flexible Transceivers Deploying Inverse Fast Fourier Transform/Fast Fourier Transform-Based Processing

“…It is also interesting to point out that when the last IFFT operation size is fixed, the optimal clipping ratio is independent of channel count, as verified in Figure 8 . As seen in Figure 10 , with the identified optimal clipping ratio, when the channel count increases, the maximum aggregated transmission capacity is slightly reduced because of clipping-induced channel interferences [ 1 ], and it can also be found that every additional two-channel increase in the channel count can only lead to <1.2 Gb/s reductions in the aggregated capacity when the channel count is >4. As illustrated in Figure 9 , when the size of the last IFFT operations is fixed, clipping ratio has a linear relationship with CSPR, which is independent of channel count.…”

“…It can be seen from Figure 5 and Figure 6 that clipping can effectively reduce PAPRs by introducing signal distortions [ 18 ]. Such signal distortions can result in unwanted channel interferences [ 1 , 11 ], which can be further mitigated by adopting clipping noise cancellation techniques [ 19 ].…”

“…W is the aggregated signal size for the (r − 1)-th IFFT operation. Equation (1) indicates that the r-th IFFT operation size doubles the size of the (r − 1)-th IFFT operation. As seen in Figure 2b, for the (r − 1)-th IFFT operation, the two input signals to be aggregated are A = [a0, a1, …, aW−1] and B = [b0, b1, …, bW−1], where signal A presents the output of the (r − 2)-th IFFT operation, and B is the input signal aggregated by the (r − 1)th IFFT operation.…”

“…Digital signal processing (DSP) plays a vital role in constructing flexible optical transceivers to considerably improve optical networks’ flexibility, elasticity, and adaptability [ 1 ]. In the practical implementations of the highly desirable flexible transceivers, cost-effective DSP-based multi-channel aggregation and de-aggregation techniques are employed to flexibly and dynamically aggregate and de-aggregate multiple independent channels of various line rates according to actual end-user requirements.…”

Point‐to‐point intensity modulation and direct detection flexible transceivers incorporating cascaded inverse fast fourier transform/fast fourier transform‐based multi‐channel aggregation/de‐aggregation techniques

“…The conventional IMDD transceivers can only operate at predefined speeds and provide static and fixed-grid connections [3]. They thus cannot cost-effectively meet the stringent requirements of the next generation of optical access networks and mobile access networks in terms of flexibility, elasticity, scalability, and upgradability [4][5][6].…”