Planning & Design
For premises networks, we planned and design the cable system is design to carry computer networks (LAN, local area network) based on Ethernet which currently may operate at speeds from 10 megabits per second to 10 gigabits per second. The typical LAN has copper and fiber sections and links to wireless access points for universal Wi-Fi connectivity. Data centers are unique applications that house multiple Internet servers and storage networks operating at very high speeds using combinations of short copper and fiber links. Other systems may carry security systems with digital or analogue video, perimeter alarms or entry systems, which are usually low speeds, at least as far as fiber is concerned. Premises telephone systems can be carried on traditional twisted pair cables or, as is becoming more common, utilize LAN cabling with voice over IP (VoIP) technology.
Premises networks are usually short, often less than the 100 meters (about 330 feet) used as the limit for standardized structured cabling systems that allow twisted pair copper or fiber optic cabling, with backbones on campus networks used in industrial complexes or institutions as long as 500 m or more, requiring optical fiber.
Premises networks generally operate over multi mode fiber. Multi mode systems are less expensive than single mode systems, not because the fiber is cheaper (it isn't) nor because cable is cheaper (the same), but because the large core of multi mode fiber allows the use of cheaper LED or VCSEL sources in transmitters, making the electronics much cheaper. Astute designers and end users often include both multi mode and single mode fibers in their backbone cables (called hybrid cables) since single mode fibers are very inexpensive and it provides a virtually unlimited ability to expand the systems. LANs and data centers operating at speeds over 10 GB/s are migrating to single mode fiber so more premises cabling systems include single mode.
Premises networks will include an entrance facility where outside plant and premises communications systems meet. This facility must include not only cabling connections but compatible communications equipment. Since it is indoors, it must consider issues for building and electrical codes, such as the common requirement that bare OSP cables can only come 50 feet (about 15 meters) before being terminated in fire-rated cables unless it is in conduit.
Outside Plant Networks
We do have experiences on outside plant networks. Outside plant networks refers to all systems that are outdoors, not inside buildings or campuses. They are typically longer networks uses for telecom, CATV, utilities, security, metropolitan networks, etc.
Telephone networks are mainly outside plant (OSP) systems, connecting buildings over distances as short as a few hundred meters to hundreds or thousands of kilometers. Data rates for telecom are typically 2.5 to 10 gigabits per second using very high power lasers that operate exclusively over single mode fibers. The big push for telecommunication provider is now taking fiber directly to a commercial building or the home, since the signals are now too fast for traditional twisted copper pairs.
There are many other OSP applications of fiber. Intelligent highways are dotted with security cameras and signs and/or signals connected on fiber. Security monitoring systems in large buildings like airports, government and commercial buildings, casinos, etc. are generally connected on fiber due to the long distances involved. Like other networks, premises applications are usually multi mode while OSP is single mode to support longer links.
Metropolitan networks owned and operated by cities can carry a variety of traffic, including surveillance cameras, emergency services, educational systems, telephone, LAN, security, traffic monitoring and control and sometimes even traffic for commercial interests using leased bandwidth on dark fibers. However, since most are designed to support longer links than premises or campus applications, single mode is the fiber of choice.
For all except premises applications, fiber is the communications medium of choice, since its greater distance and bandwidth capabilities make it either the only choice or considerably less expensive than copper or wireless. Only inside buildings is there a choice to be made, and that choice is affected by economics, network architecture and the tradition of using copper inside buildings. Next, we’ll look at the fiber/copper/wireless choices in more detail.
Copper, Fiber or Wireless
While discussions of which is better – copper, fiber or wireless – has enlivened cabling discussions for decades, it’s becoming moot. Communications technology and the end user market, it seems, have already made decisions that generally dictate the media and many networks combine all three. We at BNS as designer of cabling networks, especially fiber optic networks, and their customers today generally have a pretty easy task deciding which media to use once the communications systems are chosen.
Long Distance and Outside Plant Cabling
Other than Telco systems that still use copper for the final connection to the home, practically every cable in the telephone system is fiber optic. The Internet backbone is all fiber. Most commercial buildings in populous areas have direct fiber connections from communications suppliers. Cities use SM fiber to connect municipal buildings, surveillance cameras, and traffic signals and sometimes offer commercial and residential connections, all over single mode fiber. Even cellular antenna towers along highways and on tall buildings usually have fiber connections.
In matters related to long distance or outside plant applications, we at BNS generally choose cabling containing single mode (SM) fiber over all other media. Most of these systems are designed to be used over distances and speeds that preclude anything but SM fiber. Occasionally other options may be more cost effective, for example if a company has two buildings on opposite sides of a highway, a line-of-sight or radio optical wireless network may be easier to use since they have lower cost of installation and are easier to obtain relevant permits.
The choice of the actual single mode fiber, however, can depend on the application. Depending on the length of the link, the wavelength of the transmitters, data rate of the transmission and if CWDM or DWDM are planned, different types of fiber may be optimal.
The desire for mobility, along with the expansion of connected services, appears to lead to a new type of corporate network to be entertained. Fiber optic backbone with copper to the desktop where people want direct connections and multiple wireless access points, more than is common in the past, for full coverage and maintaining a reasonable number of users per access point is the new norm for corporate networks. Most building management systems use proprietary copper cabling, for example thermostat wiring and paging/audio speaker systems. Security monitoring and entry systems, certainly the lower cost ones, still depend on coax copper cable, although high security facilities like government and military installations often pay the additional cost for fiber’s more secure nature.
Surveillance systems are becoming more prevalent in buildings, especially governmental, banking, or other buildings that are considered possible security risks. While coax connections are common in short links and structured cabling advocates say you can run cameras limited distances on Cat 5E or Cat 6 UPT like computer networks, fiber has become a much more common choice. Besides offering greater flexibility in camera placement because of its distance capability, fiber optic cabling is much smaller and lightweight, allowing easier installation, especially in older facilities like airports or large buildings.
When these premises communications systems connect to the outside world, it is generally to single mode optical fiber. The entrance facility and equipment room must accommodate the equipment needed to make those connections.
Planning for a project is critical to the success of the project. The best way is to develop a checklist before beginning the design process. The checklist below is comprehensive but each project will have some of its own unique requirements that need to be added. Not all steps need be done serially, as some can be done in parallel to reduce time required for designing the project. The designer needs to interact with many peoples and organizations in designing a project. As such, it is our practice to record and maintain relevant particulars of contacts involved in the projects in the design documentation.
In our design process, we initially establish all the requirements of Link communications. These are as follows:
· Choose the link rout, carry out inspected, identify special requirements noted including inspections & permits
· Specify communications equipment and component requirements
· Specify cable plant components
· Determine coordination with facilities, electrical and other personnel
· Documentation completed and ready for installation
· Write test plan
· Write restoration plans
Package for the installation
· Documentation, drawings, bills of materials, instructions
· Permits available for inspection
· Guidelines to inspect workmanship at every step, test plan
· Daily review of progress, test data
· Safety rules to be posted on the job site(s) and reviewed with all supervisors and installation personnel
Requirements for completion of cable plant installation
· Final inspection
· Review test data on cable plant
· Instructions to set up and test communications system
· Final update of documentation
· Update and complete restoration plan, store components and documentation