A. Zapata

Bio: A. Zapata is an academic researcher from University College London. The author has contributed to research in topics: Metro Ethernet & Network architecture. The author has an hindex of 5, co-authored 13 publications receiving 143 citations.

Next-generation 100-gigabit metro ethernet (100 GbME) using multiwavelength optical rings

Abstract: This paper investigates the challenges for developing the current local area network (LAN)-based Ethernet protocol into a technology for future network architectures that is capable of satisfying dynamic traffic demands with hard service guarantees using high-bit-rate channels (80...100 Gb/s). The objective is to combine high-speed optical transmission and physical interfaces (PHY) with a medium access control (MAC) protocol, designed to meet the service guarantees in future metropolitan-area networks (MANs). Ethernet is an ideal candidate for the extension into the MAN as it allows seamless compatibility with the majority of existing LANs. The proposed extension of the MAC protocol focuses on backward compatibility as well as on the exploitation of the wavelength domain for routing of variable traffic demands. The high bit rates envisaged will easily exhaust the capacity of a single optical fiber in the C band and will require network algorithms optimizing the reuse of wavelength resources. To investigate this, four different static and dynamic optical architectures were studied that potentially offer advantages over current link-based designs. Both analytical and numerical modeling techniques were applied to quantify and compare the network performance for all architectures in terms of achievable throughput, delay, and the number of required wavelengths and to investigate the impact of nonuniform traffic demands. The results show that significant resource savings can be achieved by using end-to-end dynamic lightpath allocation, but at the expense of high delay.

Service differentiation in wavelength-routed optical burst-switched networks

Abstract: The request scheduler carrying out the QoS provisioning with service differentiation was analysed for the wavelength-routed OBS network architecture. QoS performance for two traffic classes was analysed in terms of the burst blocking probability and end-to-end delays and as a function of the constraint of core wavelength over-provisioning. The results show that the WROBS is capable of a very efficient QoS performance, whilst significantly minimising the core wavelength requirement with regards to the statically-routed networks. It is demonstrated that the QoS provisioning for the premium traffic does not trade off the blocking probability of the best-effort traffic. Moreover, even with no core wavelength over-provisioning in WROBS, the desired blocking probability can be achieved for both premium and best-effort traffic whilst the delay bounds for both classes are not exceeded. The reported results are directly applicable for the provisioning of the guaranteed IP services and for RWA optimisation.

Dynamic wavelength-routed optical burst-switched networks: scalability analysis and comparison with static wavelength-routed optical networks

Abstract: Analytic equations are developed to quantify the maximum network size supported by a centralized dynamic optical network architecture. Comparison with static networks establishes the maximum traffic load for which wavelength resources reduction is achievable.

Impact of burst aggregation schemes on delay in optical burst switched networks

Abstract: This work compares the maximum delay in five different burst assembly schemes. The mean packet delay is analytically derived and evaluated by simulation for Poisson and non-Poisson input traffic. The results allow to define an optimum burst assembly scheme in terms of the introduced delay.

Performance comparison of static and dynamic optical metro ring architectures

Abstract: Four static and dynamic optical ring network architectures are analysed in terms of end-to-end delay, throughput and wavelength requirements, for implementation in future metropolitan area networks.

Optical Packet and Burst Switching Technologies for the Future Photonic Internet

Abstract: This paper reviews advanced optical burst switching (OBS) and optical packet switching (OPS) technologies and discusses their roles in the future photonic Internet. Discussions include optoelectronic and optical systems technologies as well as systems integration into viable network elements (OBS and OPS routers). Optical label switching (OLS) offers a unified multiple-service platform with effective and agile utilization of the available optical bandwidth in support of voice, data, and multimedia services on the Internet Protocol. In particular, OLS routers with wavelength routing switching fabrics and parallel optical labeling allow forwarding of asynchronously arriving variable-length packets, bursts, and circuits. By exploiting contention resolution in wavelength, time, and space domains, the OLS routers can achieve high throughput without resorting to a store-and-forward method associated with large buffer requirements. Testbed demonstrations employing OLS edge routers show high-performance networking in support of multimedia and data communications applications over the photonic Internet with optical packets and bursts switched directly at the optical layer

Optical Burst Switched Networks

Abstract: Next-generation high-speed Internet backbone networks will be required to support a broad range of emerging applications which may not only require significant bandwidth, but may also have strict quality of service (QoS) requirements. Furthermore, the traffic from such applications are expected to be highly bursty in nature. For such traffic, the allocation of static fixed-bandwidth circuits may lead to the over-provisioning of bandwidth resources in order to meet QoS requirements. Optical burst switching (OBS) is a promising new technique which attempts to address the problem of efficiently allocating resources for bursty traffic. In OBS, incoming data is assembled into bursts at the edges of the network, and when the burst is ready to be sent, resources in the network are reserved only for the duration of the burst. The reservation of resources is typically made by an out-of-band one-way control message which precedes the burst by some offset time. By reserving resources only for the duration of the burst, a greater degree of utilization may be achieved in the network. This book provides an overview of optical burst switching. Design and research issues involved in the development of OBS networks are discussed, and approaches to providing QoS in OBS networks are presented. Topics include: - Optical burst switching node and network architectures - Burst assembly - Signaling protocols - Contention resolution - Burst scheduling - Quality of service in OBS networks

100Gbit/s DQPSK Transmission Experiment without OTDM for l00G Ethernet Transport

Abstract: We demonstrate 100Gbit/s DQPSK transmission experiment over 50km SMF. Without resorting OTDM, 100Gbit/s transmission was enabled with DQPSK format and commercially available electronics. Possibility of DQPSK modulation for future 100G Ethernet transport is verified.

Using LDPC-Coded Modulation and Coherent Detection for Ultra Highspeed Optical Transmission

Abstract: We propose the coded modulation schemes for ultrahigh-speed transmission (100 Gb/s and above) by using commercially available components operating at 40 gigasymbols/s. The bit-interleaved coded modulation in combination with the low-density parity-check codes that are used as component codes has been applied. The modulation is based on either M-ary quadrature-amplitude modulation or M-ary phase-shift keying. bits are mapped into the corresponding signal constellation point using either Gray or natural mapping. The coherent detection scheme has been found to outperform the direct detection one and to provide an additional margin much needed for longer transmission distances or for application in an all-optical network scenario.

Next-generation 100-gigabit metro ethernet (100 GbME) using multiwavelength optical rings

Abstract: This paper investigates the challenges for developing the current local area network (LAN)-based Ethernet protocol into a technology for future network architectures that is capable of satisfying dynamic traffic demands with hard service guarantees using high-bit-rate channels (80...100 Gb/s). The objective is to combine high-speed optical transmission and physical interfaces (PHY) with a medium access control (MAC) protocol, designed to meet the service guarantees in future metropolitan-area networks (MANs). Ethernet is an ideal candidate for the extension into the MAN as it allows seamless compatibility with the majority of existing LANs. The proposed extension of the MAC protocol focuses on backward compatibility as well as on the exploitation of the wavelength domain for routing of variable traffic demands. The high bit rates envisaged will easily exhaust the capacity of a single optical fiber in the C band and will require network algorithms optimizing the reuse of wavelength resources. To investigate this, four different static and dynamic optical architectures were studied that potentially offer advantages over current link-based designs. Both analytical and numerical modeling techniques were applied to quantify and compare the network performance for all architectures in terms of achievable throughput, delay, and the number of required wavelengths and to investigate the impact of nonuniform traffic demands. The results show that significant resource savings can be achieved by using end-to-end dynamic lightpath allocation, but at the expense of high delay.