Frequency interleaving towards spectrally efficient directly detected optical OFDM for next-generation optical access networks

Abstract

In this paper, we theoretically analyze and demonstrate that spectral efficiency of a conventional direct detection based optical OFDM system (DDO-OFDM) can be improved significantly using frequency interleaving of adjacent DDO-OFDM channels where OFDM signal band of one channel occupies the spectral gap of other channel and vice versa. We show that, at optimum operating condition, the proposed technique can effectively improve the spectral efficiency of the conventional DDO-OFDM system as much as 50%. We also show that such a frequency interleaved DDO-OFDM system, with a bit rate of 48 Gb/s within 25 GHz bandwidth, achieves sufficient power budget after transmission over 25 km single mode fiber to be used in next-generation time-division-multiplexed passive optical networks (TDM-PON). Moreover, by applying 64- quadrature amplitude modulation (QAM), the system can be further scaled up to 96 Gb/s with a power budget sufficient for 1:16 split TDM-PON.

QAM accommodated double-side band fast OFDM based on IDCT

“…Multiple sub-carriers technology has gained much attention in recent years as it provides a relatively straightforward way to accommodate high data rate link. Orthogonal frequency division multiplexing (OFDM) is a typical multiple sub-carriers modulation format [1][2][3]. It enjoys a much higher spectrum efficiency (SE) than many other multiple sub-carriers technologies as a result of overlapped orthogonal sub-carriers.…”

“…[7][8][9][11][12][13]17] pointed out that this scheme can only be modulated by 1-dimension modulation formats, such as amplitude shift keying (ASK) and binary phase shift keying (BPSK). The commonly used 2-dimension modulation formats with higher SE, such as quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM), can not be utilized in FOFDM [11][12][13][17][18][19][20]; while OFDM is commonly QAM modulated [1][2][3][4][5][6].…”

Proof-of-Concept Experiment of Duty Cycle Division Multiplexing with Bit Error Rate Analysis

“…Multiplexing allows many users to share a transmission medium, thus reducing the total cost and complexity. Time Division Multiplexing (TDM) [1][2][3], Frequency Division Multiplexing (FDM) or Orthogonal FDM (OFDM) [4][5][6], and Code Division Multiplexing (CDM) [7][8][9] are among the popular alternatives. In optical fiber communications, with the introduction of Erbium-Doped Fiber Amplifier (EDFA) [10][11][12][13], Wavelength Division Multiplexing (WDM) [14][15][16] technology becomes feasible and emerges as the technology of choice in the telecommunication industry.…”