Novel WDM Access Network Featuring Self-healing Capability and Flexible Extensibility

2021

Sensors

A new type of passive single-line bidirectional optical add/drop multiplexer (SBOADM) is proposed and experimentally demonstrated. When the proposed SBOADM is placed as a node of a ring topology optical fiber network, the special routing function of the SBOADM can always drop down the desired downstream signals whether the signals are injected into the SBOADM in either the clockwise (CW) or counterclockwise (CCW) direction and can upload and send back the upstream signals via the reversed optical pathway of the downstream signals. Once fiber link failure occurs in the optical network, the blocked network connections can be recovered immediately by sending out the downstream signals in both the CW and CCW directions of the fiber ring. As in all passive devices, the SBOADM needs no power supply or complicated network management to achieve the bidirectional function. Thus, the proposed device is an optimal solution to enhance the stability and reliability of rapidly developed optical fiber networks.

Section: Introductionmentioning

confidence: 99%

Single-Line Bidirectional Optical Add/Drop Multiplexer for Ring Topology Optical Fiber Networks

2021

Sensors

“…Embedding wavelength division multiplexing (WDM) technique into time-division multiplexing (TDM) based treetopology network will be a suitable solution for overcoming this limitation [16]. If an optical multiplexing/de-multiplexing component, such as an arrayed waveguide grating (AWG), is added into the remote node (RN) of the tree-topology RoF transport systems to route different wavelengths of light carriers to different feeder fibers and significantly increase the number of BSs that can be served per feeder fiber [17,18]. The main drawbacks of such hybrid architecture are the limited scalability and flexibility of extending or reorganizing AWG's optical routing characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…In parallel with utilizing AWGs to form the hybrid TDM and WDM RoF network mentioned above, some scholars have proposed forming hybrid TDM and WDM RoF networks with better flexibility by utilizing an integrated ring and tree structure network instead of using only a tree structure [18][19][20]. Such hybrid network architecture provides a potential self-disconnection repair capability that can overcome unexpected fiber-link failure by using an optical add/drop multiplexer (OADM) to bridge optical wavelengths transmitted between the ring and tree topology.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Ring- and Tree-Topology RoF Transmission System with Disconnection Protection

2021

Photonics

This paper proposes a hybrid ring- and tree-topology radio over fiber (RoF) transmission system with self-disconnection protection that can support the high distribution density of base stations (BSs) in a metropolitan area and strengthen the network quality of service through self-disconnection protection. The number of supportable BS in the system can be increased significantly by integrating the time- and wavelength-division multiplexing techniques and properly utilizing a new-generation single-line bidirectional add/drop multiplexer (SBOADM) into the proposed system. Moreover, when the ring–fiber link of the system is interrupted for any reason, the system operator can recover the broken connections quickly only by transforming an optical switch state at the CO end to allow the downlink optical signals to transmit along the clockwise and counterclockwise directions of the ring–fiber link simultaneously. In this case, the downstream optical signals can be delivered to each set of BS-groups through the two-way transmission characteristics of the SBOADM automatically, and the uplink optical signals, originally, from each set of BS-groups can be transmitted back to the CO end along the opposite direction of the downlink signal-routing path. In this way, the interference caused by fiber breakage can be avoided immediately, and the entire transport system can be reconnected to ensure the quality of network services. Our experimental results prove that the overall transmission performances are similar to those under normal circumstances.

“…Radio over fiber (RoF) transport systems have been developed to support broadband wireless communication technologies, such as 5G and WiGig. Typically, RoF transport systems in ring topology can utilize wavelength division multiplexing (WDM) technology to extend the network capacity [1,2] and to provide a better self-healing function compared with tree-topology architectures to overcome fiber line failures [3,4,5,6]. However, if the ring-topology comprises a traditional optical add/drop multiplexer (OADM) [7,8], the transport system may be unable to exercise its self-healing function when a fiber link failure is present because both the added and passed optical signals in an OADM are transmitted in the same direction of the fiber ring [9].…”

Section: Introductionmentioning

confidence: 99%

Fiber Link Health Detection and Self-Healing Algorithm for Two-Ring-Based RoF Transport Systems

Tsai

et al. 2019

Sensors

A two-ring-based radio over fiber (RoF) transport system with a two-step fiber link failure detection and self-healing algorithm is proposed to ensure quality of service (QoS) by automatically monitoring the health of each fiber link in the transport system and by resourcefully detecting, locating, and bypassing the blocked fiber links. With the assistance of the fiber Bragg grating remote sensing technique, preinstalled optical switches, and novel single-line bidirectional optical add/drop multiplexers, the optical routing pathways in the RoF transport system can be dynamically adjusted by the proposed algorithm when some fiber links are broken. Simulation results show that except in some extreme situations, the proposed algorithm can find the blocked fiber links in the RoF transport system and animatedly adjust the status of preinstalled optical switches to restore all blocked network connections, thereby ensuring QoS in the proposed RoF transport system.