The integration of optical and wireless systems is considered to be one of the most promising solutions for increasing the existing capacity and mobility as well as decreasing the costs in next-generation optical access networks. In this paper, several key enabling technologies for hybrid optical-wireless access networks are described, including optical millimeter-wave (mm-wave) generation, upconversion, and transmission in a downlink direction, and full-duplex operation based on wavelength reuse by using a centralized light source in an uplink direction. By employing these enabling technologies, we design and experimentally demonstrate an optical-wireless testbed that is simultaneously delivering wired and wireless services in the integrated optical-wireless and wavelength-division-multiplexing passive-optical-network access networks. The actual applications consisting of 270-Mb/s uncompressed standard-definition TV signal and 2.5-Gb/s data channels for downstream are successfully transmitted over a 25-km fiber and a 10.2-m indoor wireless link with less than a 1.5-dB power penalty. The results show that this integrated system is a practical solution to deliver superbroadband information services to both stationary and mobile users.

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A fault recovery system that is fast and reliable is essential to today's networks, as it can be used to minimize the impact of the fault on the operation of the network and the services it provides. This paper proposes a methodology for performing automatic protection switching (APS) in optical networks with arbitrary mesh topologies in order to protect the network from fiber link failures. All fiber links interconnecting the optical switches are assumed to be bidirectional. In the scenario considered, the layout of the protection fibers and the setup of the protection switches is implemented in nonreal time, during the setup of the network. When a fiber link fails, the connections that use that link are automatically restored and their signals are routed to their original destination using the protection fibers and protection switches. The protection process proposed is fast, distributed, and autonomous. It restores the network in real time, without relying on a central manager or a centralized database. It is also independent of the topology and the connection state of the network at the time of the failure.

An ultra-low latency, high throughput Internet protocol (IP) over wavelength division multiplexing (WDM) packet switching technology for next-generation Internet (NGI) applications has been designed and demonstrated. This method overcomes limitations of conventional optical packet switching, which require buffering of packets and synchronization of bits, and optical burst switching methods that require estimation of delays at each node and for each path. An optical label switching technique was developed to realize flexible bandwidth-on-demand packet transport on a reconfigurable WDM network. The aim was to design a network with simplified protocol stacks, scalability, and data transparency. This network will enable the NGI users to send their data applications at gigabit/second access speed with low and predictable latency (<1 /spl mu/sec per switch node), with a system capacity of beyond multi-Tb/s. Packet forwarding utilizes WDM optical headers that are carried in-band on the same wavelength and modulated out-of-band in the frequency domain.

This paper reviews and outlines the key features of the emerging next-generation fixed passive optical network (NG-PON)-based and fourth-generation (4G) mobile broadband access technologies and how to leverage the advantages of both of these access technologies to build a next-generation hybrid fiber-wireless (FiWi) network. Specifically, this paper presents an overview of the most recent research activities on these hybrid FiWi architectures, aiming to clarify the basic differences and distinguish between two FiWi networking architectural models, namely, the overlay or independent model and the truly integrated model. We then explore and present a new direction to the design and implementation of a simple and cost-effective all-packet-based converged fixed-mobile access networking solution that enables the true integration of NG-PON and 4G mobile broadband access technologies into the envisioned fixed-mobile platform. We briefly outline the general and technical requirements to support a unified NG-PON long-term evolution (LTE) radio access network (RAN) architecture that conforms to both the typically centralized fixed PON and the emerging distributed 4G mobile LTE access standards. The implementation methodology on how to efficiently and cost-effectively integrate these two access technologies along with the main advantages gained from such an integrated architecture are outlined and presented.