寬頻光纖擷取網路架構及實現

Abstract

本論文主要提出四個網路架構：星形-環形架構，改良式星形-環形架構，星形-巴士-環形架構及雙向路徑保護環形架構。這些架構是由傳統拓樸如星形，巴士及環形的混合而成，同時加入一些保護及故障回復的功能。首先，在被動星形-環形光網路上提出一串聯加取轉換器結構，此結構能有效地及有系統地解決光干擾的問題。這個設計使得低層環形網路完全消除光干擾。 其次，我們証實一個可行的改良式星形-環形架構，它採用適當的最佳二階網路架構，上層是星形次網路隨後串接多個具有自癒式功能的環形次網路。自癒式的功能可以在遠端節點執行，當鏈路斷路時藉由光開關可重組環形次網路，每一節點均採用串連加取轉換器結構以消除光干擾的問題。當考量網路容量、光干擾消除能力、服務品質及最初安裝的費用等因素時，這架構是一合宜的選擇。接著提出一個嶄新的高密度分波多工/次載波多工網路，它採用三階星形-巴士-環形架構。星形次網路建立一個高容量的基礎，接著巴士次網路提供一個多波長往返低層環形次網路的頻寬通道。在環形次網路上，每一光網路單元亦使用串連加取轉換器結構去消除光干擾問題。此架構同時提供一兩階層的保護裝置。 最後，兩階雙向路徑保護環形架構被提出應用於寬頻光纖-無線接取網路上。這架構能執行自癒式功能當鏈路斷路時，同時可提供高穩定度及良好的彈性度。網路的上下行次載波通道採用頻寬效率較佳的16-QAM調變技術。故此架構提供一個高穩定度、高效率及大頻寬給無線終端用戶。

This dissertation mainly includes four network architectures: the star-ring architecture (SRA), the modified star-ring architecture (MSRA), the star-bus-ring architecture (SBRA) and the bidirectional path-protected ring architecture (BPRA). These architectures are hybrids of the traditional topologies such as star, bus and ring with a few protected and restored functions. First, we proposed a cascade add/drop transceiver (CAT) structure in the passive optical star-ring networks to effectively and systematically solve the OBI problem. This work, being a system approach to deal with the problem, eliminates optical beat interference (OBI) completely in the lower level ring networks by using the CAT in each optical network unit (ONU). Next we demonstrated a modified star-ring architecture (MSRA) which employs a properly optimized two-level network architecture with self-healing capabilities on the lower level. The self-healing function can be performed at remote nodes (RN) by using optical switches to reconfigure the ring subnets if any link fails. This architecture is a feasible choice in terms of the network capacity, the OBI-reducing capability, the quality of service (QoS), and the cost of initial installation. Moreover, we proposed a novelDWDM and subcarrier multiplexing network, which employs a properly designed three-level star-bus-ring architecture (SBRA). The star subnet establishes a high-capacity infrastructure for the network, whereas the bus subnets offer broadband channels for multi-wavelength signals to and from the lower-level ring subnets. In the ring subnets, we also adopted the CAT structure at each ONU to overcome OBI problem, and a simple surviving scheme based on two protected stages in the SBRA. Finally, A two-level BPRA for a broadband fiber-wireless access network is proposed. This architecture can perform self-healing function under link failure and provide high reliability and excellent flexibility. The 16-QAM modulated signals are used in this network to achieve better spectral efficiency on both up/downstream subcarrier channels. This architecture can provide high reliability and large bandwidth for the wireless end-users.