{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:20:04Z","timestamp":1760235604520,"version":"build-2065373602"},"reference-count":32,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2021,9,2]],"date-time":"2021-09-02T00:00:00Z","timestamp":1630540800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A novel transmission technique\u2014namely, a DFT-spread spectrally overlapped hybrid OFDM\u2013digital filter multiple access (DFMA) PON based on intensity modulation and direct detection (IMDD)\u2014is here proposed by employing the discrete Fourier transform (DFT)-spread technique in each optical network unit (ONU) and the optical line terminal (OLT). Detailed numerical simulations are carried out to identify optimal ONU transceiver parameters and explore their maximum achievable upstream transmission performances on the IMDD PON systems. The results show that the DFT-spread technique in the proposed PON is effective in enhancing the upstream transmission performance to its maximum potential, whilst still maintaining all of the salient features associated with previously reported PONs. Compared with previously reported PONs excluding DFT-spread, a significant peak-to-average power ratio (PAPR) reduction of over 2 dB is achieved, leading to a 1 dB reduction in the optimal signal clipping ratio (CR). As a direct consequence of the PAPR reduction, the proposed PON has excellent tolerance to reduced digital-to-analogue converter\/analogue-to-digital converter (DAC\/ADC) bit resolution, and can therefore ensure the utilization of a minimum DAC\/ADC resolution of only 6 bits at the forward error correction (FEC) limit (1 \u00d7 10\u22123). In addition, the proposed PON can improve the upstream power budget by &gt;1.4 dB and increase the aggregate upstream signal transmission rate by up to 10% without degrading nonlinearity tolerances.<\/jats:p>","DOI":"10.3390\/s21175903","type":"journal-article","created":{"date-parts":[[2021,9,2]],"date-time":"2021-09-02T23:05:12Z","timestamp":1630623912000},"page":"5903","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["DFT-Spread Spectrally Overlapped Hybrid OFDM\u2013Digital Filter Multiple Access IMDD PONs"],"prefix":"10.3390","volume":"21","author":[{"given":"Abdulai","family":"Sankoh","sequence":"first","affiliation":[{"name":"School of Computer Science and Electronic Engineering, Bangor University, Bangor LL57 1UT, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6913-8265","authenticated-orcid":false,"given":"Wei","family":"Jin","sequence":"additional","affiliation":[{"name":"School of Computer Science and Electronic Engineering, Bangor University, Bangor LL57 1UT, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4293-8246","authenticated-orcid":false,"given":"Zhuqiang","family":"Zhong","sequence":"additional","affiliation":[{"name":"School of Computer Science and Electronic Engineering, Bangor University, Bangor LL57 1UT, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiaxiang","family":"He","sequence":"additional","affiliation":[{"name":"School of Computer Science and Electronic Engineering, Bangor University, Bangor LL57 1UT, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yanhua","family":"Hong","sequence":"additional","affiliation":[{"name":"School of Computer Science and Electronic Engineering, Bangor University, Bangor LL57 1UT, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2111-5830","authenticated-orcid":false,"given":"Roger","family":"Giddings","sequence":"additional","affiliation":[{"name":"School of Computer Science and Electronic Engineering, Bangor University, Bangor LL57 1UT, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jianming","family":"Tang","sequence":"additional","affiliation":[{"name":"School of Computer Science and Electronic Engineering, Bangor University, Bangor LL57 1UT, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"67512","DOI":"10.1109\/ACCESS.2020.3031234","article-title":"A survey on beyond 5G network with the advent of 6G: Architecture and emerging technologies","volume":"9","author":"Dogra","year":"2021","journal-title":"IEEE Access"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1109\/JLT.2016.2617896","article-title":"Multidimensional convergence in future 5G networks","volume":"35","author":"Ruffini","year":"2017","journal-title":"J. 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