Abstract
We propose and experimentally demonstrate a new scheme to reduce the energy consumption of optical network units (ONUs) in orthogonal frequency division multiplexing passive optical networks (OFDM PONs) by using time-domain interleaved OFDM (TI-OFDM) technique. In a conventional OFDM PON, each ONU has to process the complete downstream broadcast OFDM signal with a high sampling rate and a large FFT size to retrieve its required data, even if it employs a portion of OFDM subcarriers. However, in our scheme, the ONU only needs to sample and process one data group from the downlink TI-OFDM signal, effectively reducing the sampling rate and the FFT size of the ONU. Thus, the energy efficiency of ONUs in OFDM PONs can be greatly improved. A proof-of-concept experiment is conducted to verify the feasibility of the proposed scheme. Compared to the conventional OFDM PON, our proposal can save 17.1% and 26.7% energy consumption of ONUs by halving and quartering the sampling rate and the FFT size of ONUs with the use of the TI-OFDM technology.
Highlights
Due to its high spectral efficiency, flexible bandwidth allocation, and robust dispersion tolerance, orthogonal frequency division multiplexing passive optical network (OFDM PON) has attracted great interests in recent years as a promising solution to future-proof broadband access [1,2,3,4,5,6]
From the perspective of energy efficiency, OFDM PON consumes much more energy than time division multiplexing (TDM) PON, since it employs a great number of energy-hungry analog-to-digital converters/digital-to-analog converters (ADCs/DACs) and digital signal processing (DSP) chips [7]
In the optical line terminal (OLT), the data transmitted to the optical network units (ONUs) are divided into multiple groups, which are separately processed by IFFT with a small number of points to obtain several OFDM signals
Summary
Due to its high spectral efficiency, flexible bandwidth allocation, and robust dispersion tolerance, orthogonal frequency division multiplexing passive optical network (OFDM PON) has attracted great interests in recent years as a promising solution to future-proof broadband access [1,2,3,4,5,6]. From the perspective of energy efficiency, OFDM PON consumes much more energy than time division multiplexing (TDM) PON, since it employs a great number of energy-hungry analog-to-digital converters/digital-to-analog converters (ADCs/DACs) and digital signal processing (DSP) chips [7]. There still have no efforts to resolve this problem in OFDM PONs, which is more serious due to the employment of ADC/DAC and DSP chips with high energy consumption in the ONUs. In this paper, we propose a time-domain interleaved OFDM (TI-OFDM) technique to improve the energy efficiency of ONUs for OFDM PONs. In the OLT, the data transmitted to the ONUs are divided into multiple groups, which are separately processed by IFFT with a small number of points to obtain several OFDM signals. It is worth noting that a trade-off between the number of data groups and the network performance should be made since the TI-OFDM technique would induce more power penalty for the OFDM system with the increase of the number of data groups
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