A Computational Efficient Nyquist Shaping Approach for Short-Reach Optical Communications

Perez-Pascual, A.; Bruno, Julian S.; Almenar, Vicenç; Valls, Javier

doi:10.1109/jlt.2019.2961506

Cited by 1 publication

(12 citation statements)

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“…Only if a sinc pulse shaping is employed (which implies a 0 roll-off factor and a brick wall spectrum), aliasing is avoided. On the other hand, the OVS-SCM [9] proposed to increase the ADC cos(w c n) sample rate (specifically it worked with 9/4=2.25 sps) to simplify the Nyquist filter specifications and, consequently, to reduce the overall complexity of the system. Fig.…”

Section: Ovs-scm Systemmentioning

confidence: 99%

“…In this paper, we present the receiver architecture for a system that obtains several samples in parallel from the ADC. The proposal follows the OVS-SCM processing scheme, but, for optimization reasons, different sample rates along the processing chain than those from [9] are employed. Specifically, for the transmitter the pulse shaping stage interpolates by 2 (𝐴=2) and then there is a factional interpolation by 8/7 (𝐵=8 and 𝐶=7), giving a final rate of 2.2857 sps.…”

Section: Ovs-scm Systemmentioning

confidence: 99%

“…Moreover, to keep deployment costs low, optical coherent transmission is not foreseeable in the near future, so optical transmission will make use of IM/DD schemes. Therefore, this improvement in spectral efficiency will require the use of powerful digital signal processing solutions [3] and efficient modulation formats such as OFDM [2], [4], [5], [6] and SCM [7], [8], [9], [10]. This last one is the strategy developed in this paper.…”

mentioning

confidence: 99%

“…Recently, oversampled subcarrier modulation (OVS-SCM) was proposed [9], introducing a non-integer sampling rate higher than 2 and a raised cosine pulse with roll-off factor higher than zero. The authors evaluated a system with a sampling rate of 2.25 samples per symbol (sps), which was obtained with a rational interpolation/decimation rate of 9/4, and a roll-off of 0.1.…”

mentioning

confidence: 99%

“…The implementation of OVS-SCM systems is heavily influenced by the fact that they must process samples in parallel. In the case of [9], the computational load of an OVS-SCM transmitter and receiver was analyzed, but their hardware architectures were not presented. Moreover, their selected number of sps, and the associated interpolation/decimation operators do not take into account the parallelism of the processing stages, which increases the complexity and cost of the implementation.…”

mentioning

confidence: 99%

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Short-reach optical fiber communications systems aim to achieve high throughput, in the order of tens of Gbps.The implementation of these high-speed systems requires parallel processing, which makes low-complexity designs of their subsystems a key to the successful large-scale deployment of this technology. Half-Cycle Nyquist Subcarrier Modulation (HC-SCM) was originally suggested for these systems with the goal of using as much bandwidth as possible and, therefore, achieving high communication rates. Recently, Oversampled Subcarrier Modulation (OVS-SCM) was proposed as an alternative more computational efficient than HC-SCM and also with a better spectral efficiency. This paper proposes a hardware-efficient architecture for an OVS-SCM receiver, which takes into account the inherent parallel processing of these systems. This receiver takes 16 samples in parallel from a 5 GSa/s analogto-digital converter with a 3.2 GHz 3 dB bandwidth. Design solutions for the frame detection block, the mixer, the resampler, the fractional interpolator, the matched filter and the timing estimator are presented. Our results show that, compared to the HC-SCM receiver, this proposal reduces the computational load of the downconverter stages by 90%. FPGA implementation results are given to demonstrate that our proposal can be implemented in state-of-the-art devices. Index Termsshort-range optical links, FPGA, hardware architecture, receiver I. INTRODUCTION Short-reach optical fiber systems with intensity modulated direct-detection (IM/DD) transmission scheme over standard single-mode fiber (SSMF) is a potential solution to support the continuous increase in data traffic of telecommunications networks. There are three possible solutions to increase the bit rate in any communications system: to make use of more bandwidth, to increase the spectral efficiency by means of modulation formats with more bits per symbol, and to multiplex several data signals. In recent years the move from 10G to 100G in optical links has made use of a mixture of the previously stated solutions. For example, from 10G to 40G multiplexing was the chosen solution by means of four 10G links, whether transmitted using four different wavelengths, or using four different fibers. The road to 100G has been solved with different solutions, each one using a different combination of Manuscript received XX, XX; revised XX, XX. Grants RTI2018-101658-B100 and PID2021-126514OB-I00 funded by

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Section: Ovs-scm Systemmentioning

confidence: 99%

Section: Ovs-scm Systemmentioning

confidence: 99%