We propose and demonstrate a single-fiber bidirectional wavelength division multiplexing self-healing ring network for metro-access applications. By incorporating a simple bi-directional optical add-drop multiplexer at each network node as well as employing our proposed alternate-path switching scheme, the bi-directional traffic can be restored promptly under single fiber failure in the ring network. All the protection switching is performed at the hub only, thus the operation, administration and management cost can be easily optimized

We investigate the performance of maximum likelihood sequence estimation (MLSE) receiver in the presence of the impairments from both the pulse carver-data modulator timing misalignment (TM) and polarization mode dispersion (PMD) in optically amplified return-to-zero (RZ) systems. RZ modulation format is commonly used in long-haul wavelengthdivision multiplexing transmission systems and the dominating noise source in those systems is amplified spontaneous emission (ASE) noise, which is signal dependent and requires special study when direct detection is employed. In this paper, based on the bit-to-bit error probability estimation using Karhunen-Loeve (KL) expansion and decorrelation of noise components, we use the steepest descent method to obtain sequence-to-sequence error probability and achieve the performance evaluation of MLSE receiver with arbitrary input signal pulse shape, optical filtering and electrical filtering taken into consideration. Monte Carlo simulations of a 10-Gb/s RZ system are demonstrated and agree with the theory well. The results show that the power penalty induced by TM and PMD can be effectively reduced by MLSE receiver, which thus validates its capability to enhance tolerance to both TM and PMD with shared electrical devices.

Variable-bit-rate (VBR) encoded videos can provide a more consistent visual quality than constant-bit-rate (CBR) encoded videos. However, the long-range bit-rate variations in VBR videos make it difficult to efficiently provide quality-of-service control in a video-on-demand system. Existing scheduling algorithms such as Optimal Smoothing, which requires both downward and upward bandwidth reallocations to adapt to the video bit-rate variations, simply cannot guarantee video delivery in networks with mixed video and data traffic. This study tackles this limitation by investigating a new scheduling algorithm with monotonic-decreasing rate allocations for scheduling video data transmissions. By eliminating upward bandwidth reallocations, the proposed scheduler can guarantee video delivery even in the presence of other data traffic in the same network. Moreover, results show that the proposed scheduler can achieve such performance guarantee without tradeoff in performance or resource requirements. This work presents this new monotonic-decreasing rate scheduler, analyzes its fundamental properties, and evaluates its performance using a large number of real-world VBR video traces (274 DVD movies) in extensive trace-driven simulations.

This paper proposes and demonstrates a nonlinear distortion reduction scheme for subcarrier multiplexed optical CATV networks based on optical sampling and optical time-division multiplexing (OTDM) techniques. Intermodulation distortion is reduced by about 10 dB for a 40-channel system. The proposed optical sampling and OTDM process is shown to induce negligible additional distortion.

We demonstrate experimental all-optical code-division multiplexing (AO-CDM) systems using 64-picosecond optical pulses and a 2/sup n/ prime code of n=3. A distinguishing feature of this experiment is that the modulation of ultrashort optical clock stream by electrical data is realized without using any optical intensity modulator at each transmitter. Moreover, only low-cost standard optical 2/spl times/2 couplers and fiber delay lines are employed to implement all-serial encoders and decoders for a 2/sup n/ prime code. As a result, this new system is more cost- and power-effective than a conventional AO-CDM system.

ACTA (adaptive cycle tunable access) has been proposed for a high speed multimedia network. It is a simple multi-channel network protocol suitable for photonic implementation. It adopts a slotted cycle to transmit packets and the cycle length is dynamically adjusted according to the network load. We study the performance of the ACTA protocol both for single-channel and multi-channel integrated services operations. Through the simulations, we have shown that the overhead of channel tuning is quite small. We also study the priority mechanism of ACTA, and analyze the relation between the node transmission quota and bandwidth allocation. In addition, we present a slot reuse scheme which requires only one additional access control bit, and demonstrate great improvement in network utilization. The simulation results show that ACTA network is a very promising candidate for the future high speed multimedia networks.

This paper describes the design and the experimental demonstration of a novel fast channel tunable optical transmitter which is suitable for ultrahigh-speed all-optical time-division multiaccess (TDMA) networks. This optical transmitter is capable of performing fast channel tuning and data modulation in a simple and cost-effective way without using the expensive optical modulators and optical switches. By employing this transmitter, together with the proposed destructive writing scheme, ultrahigh-speed channel multiplexing with relaxed synchronization requirements for data access can be achieved. The demonstrated prototype can be arbitrarily tuned to any one of the 16 1-Gb/s channels in a 16-Gb/s all-optical TDMA network with a channel switching time of less than 5 ns. This is suitable for use in most high-speed optical time-division multiplexed (TDM) systems and tunable-channel multiaccess (TCMA) networks.