Hakjeon Bang

Determination of Sleep Period for Cyclic Sleep Mode in XG-PON Power Management

In 10-gigabit-capable passive optical network (XG-PON) power management, performance indexes such as power consumption and state transition delay of cyclic sleep mode are influenced by a sleep period. In this letter, we determine the sleep period to balance the performance tradeoff between these two conflicting goals. To do this, we perform a mathematical analysis using the state probability based on traffic arrivals. The effectiveness of the proposed model is then confirmed by the numerical results of cyclic sleep mode.

Design and Performance Analysis of Passively Extended XG-PON With CWDM Upstream

In this paper, we evaluate the design and performance of an entirely passive extended 10-gigabit-capable PON (XG-PON) using eight channels of coarse wavelength-division multiplexing (CWDM) in upstream transmission, which is called the Cu-XG-PON, with a first demonstration of the upstream physical layer specification for the extended class in ITU-T G.987 series of recommendations. In the new scheme, a single burst-mode receiver (BMRx) within an optical line terminal (OLT) receives arbitrary upstream data from the optical network terminals (ONTs) divided into eight groups, each group sharing a CWDM wavelength, through a CWDM filter and a power splitter as cascaded remote nodes (RNs) for the upstream link bridge. The downstream link is designed such that a high power OLT transmitter compensates for link loss using two power splitters as cascaded RNs. Based on the proposed architecture, we first analyze the overall system performance in the upstream and downstream links, and then evaluate the practical extension capabilities in terms of fiber distance and split ratio by conducting experiments to probe the upstream performance using a developed BMRx. We demonstrate that the BMRx is capable to -34.5 dBm sensitivity, which is feasible for a 36 dB optical path loss and a 0.5 dB optical path penalty with a 2 dBm ONT transmitter power. Based on the numerical analysis and experimental results, we confirm that the proposed Cu-XG-PON is capable of reaching 28 km for 256 ONTs, or 42 km for 64 ONTs, and furthermore, for ONT groups at long wavelength channels, maximum 40 km for 256 ONTs, or 60 km for 64 ONTs.

Analysis of ONT buffer and power management performances for XG-PON cyclic sleep mode

In a 10-gigabit-capable passive optical network (XGPON) system, a power management function such as cyclic sleep mode can be implemented to increase energy efficiency of an optical network terminal (ONT). To optimize power saving with the cyclic sleep mode, we proposed an analytic model to determine required ONT buffer size for incoming traffics from user network interface (UNI) when the ONT is sleeping, and to evaluate performances such as power consumption and delay, in accordance with buffer sizes, sleep periods, and arrival rates. Then, by simulating the proposed model, we could estimate the required buffer size and the sleep period for effective implementation of the cyclic sleep mode.

Design and analysis of IPACT-based bandwidth allocation for delay guarantee in OFDMA-PON

To guarantee delay performances for time-sensitive services in an orthogonal frequency-division multiple access passive optical network (OFDMA-PON), we propose a two-dimensional (i.e., subcarriers and time) upstream bandwidth allocation method based on interleaved polling with adaptive cycle time (IPACT). We first analyze its delay performance in terms of cycle time, i.e., the length of a polling cycle. Then, by setting the maximum polling cycle so as to guarantee timely transmissions for time-sensitive services, we identify the requirements, i.e., the maximum bandwidth allocation, the maximum number of allowed optical network units, and the optimum number of subcarriers, for upstream bandwidth allocation with delay guarantees. The proposed scheme is evaluated both numerically and via simulation.

PAPR reduction using PTS with low computational complexity in coherent optical OFDM systems

In optical communication systems for single-carrier transmission based on orthogonal frequency-division multiplexing (OFDM), high power signals result in fiber nonlinear effects such as self-phase modulation (SPM), which causes inter-symbol interference (ISI) between sub-carriers. To reduce peak-to-average power ratio (PAPR) at a transmitter of the optical OFDM system, a partial transmit sequence (PTS) technique can be applied, but it requires reduced computational complexity for practical implementation because the complexity in an optimum search over all combination of phase factors is exponentially increased with the number of sub-blocks. In this paper, a PTS method with low computational complexity is proposed by modifying an artificial bee colony (ABC) algorithm, which is an approach based on solution sets to solve combinatorial and numerical optimization problems. The effectiveness of the proposed method is confirmed by simulation results of complementary cumulative distribution function (CCDF) and BER in a coherent optical OFDM (CO-OFDM) system.

Adaptive Clock Recovery Mechanism Having Dynamic Frequency Drift and Buffer Level Control in Packet Switched Networks

Adaptive clock recovery is required in order to transmit the synchronous data of conventional time-division multiplexing (TDM) services to another TDM network across an asynchronous packet switched network (PSN). In this paper, we propose an adaptive clock recovery mechanism having dynamic frequency drift, which enables faster response with smaller residual variance, and buffer level control to reduce the required jitter buffer size with no buffer underflow or overflow.

XG-PON1 OLT transceiver with a single-chip burst-mode receiver

We present the design and evaluation of a 10-gigabit small form factor pluggable transceiver with a prototype single-chip burst-mode receiver, a signal detection circuit, and a clock-data-recovery device for 2.5 Gbit/s upstream in the ITU-T G.987.2 recommendation.

Analysis of upstream link bandwidth utilization in GPON with integrated network surveillance

We present a media access control protocol extension to integrate the physical layer surveillance concept into the transmission and the related management system in the Gigabit-capable passive optical network (GPON). We allocate an unused time slot for network surveillance depending upon its availability in the upstream GPON transmission convergence frame. We analyze the upstream link bandwidth utilization of the GPON system with network surveillance and show that there is a negligible amount of underutilization of link bandwidth as a result of this.

GPON upstream link utilization analysis with integrated network surveillance

We integrate physical layer surveillance concept into management system of GPON by allocating an unused time slot for network surveillance depending upon its availability in upstream GTC frame and analyze the link bandwidth utilization.