Koji Wakayama

Secure and scalable optical access network using PLZT high-speed optical switches

We are proposing a new optical access network architecture using PLZT 10 nsec high-speed optical switches, called Active Optical Network (ActiON). Our architecture can increase four times the number of subscribers as well as double the distance between OLT and ONUs than GE-PON. Moreover, a user can establish secure communication in ActiON. Because ActiON uses not broadcasting system but slot based switching system. ActiON has to overcome a Discovery process issue because an optical switch can not broadcast. In this paper, we propose a new Discovery process technique. Through simulation results and experimental results, we show that our proposed architecture is able to complete Discovery process with accuracy.

MPCP based active optical access network with PLZT high-speed optical switch

a b s t r a c t An active optical access network architecture with our newly developed PLZT ((Pb, La) (Zr, Ti)O3) high-speed optical switch is introduced, with a view to realizing the next- generation high capacity scalable access network. This system is developed based on the latest IEEE standard of PON (10G-EPON; IEEE802.3av) in consideration of the coordination with future high capacity PON. PLZT high-speed optical switches are able to switch an optical signal at nano-second speed (<5-10 ns). Generally, the merits of using optical switches are increasing the number of subscribers and transmission distance easily, preventing malicious ONUs from interfacing with the communication between OLT and the other ONUs, realizing fast fiber and OLT protection/restoration and providing various services by controlling optical switches dynamically. This paper focuses on two key technologies; a PLZT optical switch and a new discovery process for active optical access network based on MPCP defined at IEEE802.3. A major challenge in designing active optical access network is supporting the discovery process of MPCP because it does not offer broadcast transmission unlike the regular PON. We propose here a new discovery process; it has been tested successfully in an implementation of our proposed system.

512-ONU real-time dynamic load balancing with few wavelength reallocations in 40 Gbps λ-tunable WDM/TDM-PON [Invited]

The wavelength (λ)-tunable wavelength-division multiplexing/time-division multiplexing passive optical network (WDM/TDM-PON) can distribute traffic loads fairly by dynamically reallocating a certain number of optical network units (ONUs) from highly loaded optical subscriber units (OSUs) to lightly loaded OSUs. This reallocation can be executed by hitless λ-tuning. However, hitless λ-tuning causes delays or fluctuations in traffic. To reduce these penalties, the number of wavelength reallocations should be suppressed. Thus, we proposed a dynamic-load-balancing (DLB) algorithm that can distribute traffic loads among OSUs with few wavelength reallocations. However, no demonstration of the proposed DLB algorithm had been conducted up to now, and the impact of the reallocation frequency on the average latency remained unevaluated. In this paper, we demonstrate the DLB algorithm in a 40-Gbps λ-tunable WDM/TDM-PON. The demonstrations confirm that our DLB algorithm can distribute 512-ONU traffic loads fairly among 4 OSUs in real time with fewer reallocation frequencies compared to the conventional round-robin algorithm, and little impact on average latency, with various input traffic rates.

Simulation and Basic Experiment of Inter Radio System Handover for Cognitive Radio

Cognitive radio system consists of multiple wireless accesses that cover overlapping area, and cognitive terminals that use one or more of the wireless accesses simultaneously. In this paper, we propose the architecture of the cognitive radio system, and the inter-system handover protocols. In the proposed architecture, each cognitive terminal, that has multiple radio systems, operates with a single local IP address. The control sequence and packet format are designed to achieve fast handover among the radio systems. Based on the proposed architecture, we have developed both a simulator and a testbed system with WiMAX and wireless LAN. Through simulation and testbed, we have proved that stream data can be delivered continuously without any effects of the handover. Also, we present the evaluation result of the end-to-end latency on the testbed system.

Adaptive FEC control in downstream collaborating with traffic control in OLT for WDM/TDM-PON

We proposed adaptive FEC control that collaborates with downstream traffic control for passive optical networks. Successful operation of the adaptive FEC control in downstream based on downstream BERs of each ONU was demonstrated using a WDM/TDM-PON prototype.

Optical path protection with FEC switching in WDM/TDM-PON for ring access networks

We propose and demonstrate an optical path protection that offers FEC switching function for WDM/TDM-PON with ring topology. A system demonstration confirms proposed automatic wavelength and FEC switching enables a 30km difference of redundant optical path in ring access networks.

Real-time and fair throughput control in different OSU traffic bias with DLB algorithm for λ-tunable WDM/TDM-PON

We demonstrate real-time and fair throughput control among ONUs as realized by our dynamic-load-balancing method. Experiments on the proposal show that it achieves uniform throughput for ONUs that download 3-sec blocks of heavy traffic through OSUs with different bias levels.

Implementation of optical switch control function in Active Optical Access System

We propose an optical switch control procedure in Active Optical Access System in which optical switches are used instead of optical splitters in PON (Passive Optical Network). An OLT (Optical Line Terminal) determines the switching schedules of optical switches on OSW (Optical Switching Unit), and informs an OSW of them with a switch control frame on the proposed procedure. We demonstrate the proposed procedure works effectively with logic circuits implemented on OLT and OSW.

Distributed Control Architecture Based On In Benchmark

A new benchmark is introduced to represent the processing power for advanced telecommunication services. Traffic estimation using this benchmark shows the necessity of a distributed control architecture that provides high throughput to satisfy rapid increase of processing power in telecommunication networks. Three software architectures are proposed for a distributed network environment. Model evaluation demonstrates the efficiency of these approaches.