Confusion in classical period inscriptions suggests that the name was already ancient and unfamiliar to contemporary scribes. In one stele he is portrayed with a rope tied around his neck, and in another with an incense bag, together signifying a sacrifice to end a cycle of years. Furthermore, they assert that this event was indeed planned for and not the 7th century. It contains no speculation or prophecy as to what the scribes believed would happen at that time. Most of these are in the form of "distance dates"; Long Count dates together with an additional number, known as a Distance Number, which when added to them makes a future date.

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The Design of an FTTH access network is challenging one; it needs to compromise different factors including size, cost, and scalability. There is no standard FTTH access network model as the viability of access networks strongly depends on the subscriber density subscribers per km2 and on settlement structures, thus the modeling has to rely upon a concrete settlement structure, a given country, and the results derived depend on that country [18].

To design the Outside Plant OSP, Desk top planning does not work, each root is surveyed physically and then planned accordingly using knowledge and experience. International standards cannot be applied as each country has its own unique underground factors. Ground thermal line or freeze line should be considered to identify the point in the underground where the temperature of the surrounding soil remains constant not freezing nor overheating thus allowing for a constant temperature for the FO cable to lay in.

Another important factor that should be addressed is to decide the depth and the type of the backfill material necessary to reduce the ground vibration effects. Figure 5 summarizes the sequence of steps involved in the design of the FTTH access network in discussion.

In reference to Figure 1, the design starts with the customer premises, moving backward until reaching the central office in a bottom-up approach. The network particularly considered in this paper is required to provide service voice and data to a total of users in locations. According to the geographical separation of these locations and the number of users per individual location, FATs are used to connect these locations to the network.

Two level of splitting is used to provide a total splitting ratio of Level-1 splitters are while level-2 splitters are This means that each GPON port can serve a total of 64 users.

A bottomtop approach is used to determine the required number of GPON ports. By simple math, we can see that 16 GPON ports with 64 split ratio are quite enough to serve users. This statement is true for FTTH networks where the locations are geographically located close to each other and the number of users distributed evenly among locations, which is not our case.

Due to the constraints of our network, the number of required ports will be calculated depending on the number of FATs. As a result each FDT will be connected to one OLT card using 8 Fibers from one direction and to the backup card using 8 fibers from the other direction as shown in Figure 6.

Two feeder rings are used, the first feeder consists 12 fibers among which 8 are connected to the 8 level1 splitters inside FDT The second feeder forms the second ring connecting the other 5 FDTs. The extra 4 and 32 fibers, in the first and second feeders respectively, are reserved for future expansion or maintenance. Figures 7 and 8 show the distribution network connected to FDT-3 and FDT-4 respectively, due to space limitation the other distribution networks will not be presented, however the design procedure discussed above is followed in the design of all distribution networks of the project.

The legend presented in Figure 7 applies equally in Figure 8. The circles in the figures refer to splicing closures. The terminology adopted with FATs is to use 4 digit numbering. The first digit from the left refers to the FDT code, the second digit refers to the distribution cable sequence number and the last two digits refer to the sequence number of the fiber strand used to connect that FAT.

This terminology applies equally to distribution networks connected all other FDTs. This terminology makes the design, implementation management, reporting and future expansion easier. Two symbols are used for the FATs, the semicircle refers to FAT which only hold level-2 splitter, while the semicircle over a triangle refers to an FAT which holds level-2 splitter and provide splicing-closure function as well.

The lines refer to FO cables paths. The length of each path,.


Designing of FTTH GPON Network



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