Division Multiple Access-passive Optical Network Research Articles

Individual Stokes-Vector-Based SOP Recovery in CO-OFDMA-PON Uplink Transmission

The state of polarization (SOP) is a critical issue faced by the single-wavelength-based orthogonal frequency division multiple-access passive optical networks, because each optical network unit uses different polarization-sensitive optical devices and paths. To compensate SOP variation, an individual Stokes vector-based SOP recovery (ISVSR) technique is proposed. A single pilot-tone-based SOP compensation was individually applied and experimentally verified the effect of the ISVSR technique in the self-coherent reflective passive optical network uplink transmission. By employing individual SOP recovery, a root-mean-square compensation error and bit error rate close to zero were experimentally achieved. Consequently, the SOP variation can be quickly and accurately compensated without requiring hardware-based complex polarization control or installation of expensive devices.

Hybrid bidirectional radio-over-fiber-based orthogonal frequency division multiple access-passive optical network supporting 60 / 120 GHz using offset quadrate phase shift keying

A hybrid bidirectional orthogonal frequency division multiple access-passive optical network (OFDMA- PON) based on offset quadrate phase shift keying (OQPSK) to support 60- and 120-GHz radio-over-fiber system is proposed. The system can support wired/wireless applications and enable the dynamic bandwidth allocation according to a subscriber's application. It is successfully achieved by using the millimeter waves (MMWs) gen- eration and the carrier-reuse technique. In the proposed scheme, the MMW bands used for downlink (DL) and uplink transmissions are generated at the optical line terminal by the dual-arm Mach-Zehnder modulators. Both 60- and 120-GHz MMWs are obtained for the transmission of the high bit-rate services in source-free optical network units (ONUs), only using a single 15-GHz sinusoidal wave source. The Rayleigh backscattering effect is considered in the proposed OQPSK-based OFDMA-PON. For DL transmission over a 30-km single-mode fiber, the power penalties are less than 0.8 and 1 dB for the OQPSK-OFDM wired data at 10 Gb∕s and the OQPSK- OFDM wireless data at 5 Gb∕s, respectively. © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE) (DOI: 10.1117/1.OE.54 .9.096108)

Electrical Spreading Code-Based OFDM Optical Access Networks for Budget Enhancement and Reduced System Bandwidth Requirement

AbstractPassive optical networks based on orthogonal frequency division multiplexing (OFDM-PON) give better performance in high-speed optical access networks. For further improvement in performance, a new architecture of OFDM-PON based on spreading code in electrical domain is proposed and analytically analyzed in this paper. This approach is referred as hybrid multi-carrier code division multiple access-passive optical network (MC-CDMA-PON). Analytical results show that at bit error rate (BER) of 10

Suppression of optical beat interference-noise in orthogonal frequency division multiple access-passive optical network link using self-homodyne balanced detection

A new technique, which reduces optical beat interference (OBI) noise in orthogonal frequency division multiple access-passive optical network (OFDMA-PON) links, is proposed. A self-homodyne balanced detection, which uses a single laser for the optical line terminal (OLT) as well as for the optical network unit (ONU), reduces OBI noise and also improves the signal to noise ratio (SNR) of the discrete multi-tone (DMT) signal. The proposed scheme is verified by transmitting quadrature phase shift keying (QPSK)-modulated DMT signal over a 20-km single mode fiber. The optical signal to noise ratio (OSNR), that is required for BER of 10−5, is reduced by 2dB in the balanced detection compared with a single channel due to the cancellation of OBI noise in conjunction with the local laser.

Power margin improvement for OFDMA-PON using hierarchical modulation

We propose and experimentally demonstrate a hierarchical modulation scheme to improve power margin for orthogonal frequency division multiple access-passive optical networks (OFDMA-PONs). In a PON system, under the same launched optical power, optical network units (ONUs) have different power margins due to unequal distribution fiber lengths. The power margin of the PON system is determined by the ONU with the lowest power margin. In our proposed scheme, ONUs with long and short distribution fibers are grouped together, and downstream signals for the paired ONUs are mapped onto the same OFDM subcarriers using hierarchical modulation. In a pair of ONUs, part of the power margin of the ONU with short distribution fiber is re-allocated to the ONU with long distribution fiber. Therefore, the power margin of the ONU with the longest distribution fiber can be increased, leading to the power margin improvement of the PON system. Experimental results show that the hierarchical modulation scheme improves the power margin by 2.7 dB for an OFDMA-PON system, which can be used to support more users or extend transmission distance.