IJCSNS International Journal of Computer Science and Network Security, VOL.8 No.11, November 2008 62 Manuscript received November 5, 2008 Manuscript revised November 20, 2008 Transmission Surveillance and In-service Troubleshooting in FTTH Access Network Mohammad Syuhaimi Ab-Rahman † , Boon Chuan Ng † , Rosmawati Ismai † , Abang Anuar Ehsan †† and Sahbudin Shaari †† † Computer and Network Security Research Group, Department of Electrical, Electronics and Systems Engineering Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia †† Photonic Technology Laboratory, Institute of Micro Engineering and Nanoelectronics Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia Summary This paper proposed an approach for transmission surveillance and in-service troubleshooting for fiber-to-the-home (FTTH) access network with the combination of optical time domain reflectometer (OTDR) and passive in-line monitoring (PIM) devices. PIM device is a fully passive device that used to tap out a small ratio of triple-play signals for monitoring purpose without affecting the transmission in FTTH. The OTDR will be installed with optical line terminal (OLT) at central office (CO) for in-service monitoring and failure identifying against fiber fault in feeder region, while the PIM devices will be permanently installed with drop fibers to allow the technicians to simply connect them to a portable tester unit for transmission surveillance and failure detection in multi-line drop region. The PIM devices enable the statuses of each drop fiber and optical network unit (ONU) to be monitored through a portable tester unit. Key words: Transmission surveillance, in-service troubleshooting, FTTH, OTDR, PIM device 1. Introduction FTTH is a broadband network technology that delivering triple-play (data, voice and video) services with a high speed to the home or business via optical fiber cable. FTTH is the major role in alleviating the last mile bottleneck for next generation broadband optical access network [1]. Today, FTTH has been recognized as the ultimate solution for providing various communications and multimedia services, including carrier-class telephony, high-speed Internet access, digital cable television (CATV), and interactive two-way video-based services to the end users [2]. Owing the very high capacity of optical fibers, FTTH can deliver greater capacity as compares to copper-based technologies [3]. FTTH technology using passive optical network (PON) is the most promising way to provide high quality broadband access [4]. The PON is commonly deployed as it can offer a cost-efficient and scalable solution to provide huge- capacity optical access [5]. PON architecture consists of an OL at CO and multiple ONUs at different residential customer locations that are connected to the OLT through fibers of a tree topology. Given a certain optical split ratio (1:N, where N = 2, 4, 8, 16, 32, 64, and 128), only a limited number of ONUs can be connected to a passive optical splitter (branching device) at remote node (RN) and then connected to a common OLT [6]. The 32 or 64 ways splitting are the most common today, but other splits are possible. Since the PON can accommodate a large number of subscribers, when any fault occurs in FTTH, the network will without any function behind the break point. Any service outage due to a fiber break can be translated into tremendous financial loss in business for the network service providers [7]. A FTTH failure due to fiber break in current optical communication system could make the network service provider very difficult to restore the system back to normal. According to the cases reported to the Federal Communication Commission (FCC), more than one-third of service disruptions are due to fiber cable problems. These kinds of problems usually take longer time to resolve compared to the transmission equipment failure [8]. Therefore, the survivability of the whole network has to be examined more seriously. Lack of survivability is one of main factors that FTTH is still not been deployed in certain area. Conventionally, OTDR is used to identify a fiber fault in FTTH. Technician is sent to the ONU side to inject an OTDR pulse into the faulty fiber. By means of OTDR, one can get the distance from the fault site to the measurement site along the optical fiber housed in the optical cable [8]. However, one of the issues with testing using OTDR is this approach would produce inaccurate results if two trouble spots are very close together or if the pulse has a long travel length [9].