Is GPON Ready for Prime Time ?

September 7, 2011

Is GPON ready for prime time?  With technology, there is a natural resistance to change for fear of being on the bleeding edge, where the technology is not up to the hype. But once a new technology proves to be equal to the expectations and can be implemented at a lower cost, it is ready for prime time.

A Passive Optical Network (PON) is a network architecture using a fiber cabling point-to-multipoint design that enables a single optical fiber to serve multiple premises as an alternative to traditional copper cable.  Essentially, the light signal passes through one or many levels of beam splitters to provide a signal to many endpoints from a single strand of fiber cable.  PONs have been implemented around the world for some time now, especially in countries that had no installed base of copper cable.

It can be argued that bandwidth requirements beyond 1 Gigabit will test or exceed the cost-effective limits of copper cabling systems.  Without getting into a technical discussion, the traffic volume capacity of a PON was once considered more than adequate.  The comparative cost versus a Cat 5e or Cat 6 cabling system was the issue.  With every passing year, the implementation cost of PONs compare more favorably.  But the thirst for more and better capacity by a technology-hungry population raises the question of guaranteed capacity, placing more focus on the design of the PON.   Since “splitting the light beam” results in a shared effect of the overall bandwidth, it requires careful planning to verify the minimum acceptable bandwidth for each end-user of the signal.

There are two PON standards that are related to the design of the PON.  One is EPON (Ethernet Passive Optical Network) from IEEE (Institute of Electronics and Electrical Engineers).  The other is GPON (Gigabit Passive Optical Network) from ITU (International Telecommunications Union). Both are potential solutions for commercial developments to reduce both capital and operational expenses as an alternative to copper cabling. In recent months, the cost/benefit has received a great deal of attention.

At a recent Hotel Technology Next Generation (HTNG) meeting, I participated in a discussion panel that focused on “Fiber to the Guestroom”, a specific application of GPON.

HTNG is a global organization started in 2002 to foster collaboration between hoteliers and technology providers to promote the development of next-generation technologies which shall enable them to do business globally in the 21st century.

 

 

COPPER versus FIBER

In a hotel application, replacing the traditional copper cable infrastructure (Cat 5e, Cat 6) with fiber has been evaluated for years.  Historically, the cost/benefit analysis of Cat 6 versus fiber to the guestroom revealed two major hurdles for the fiber systems – higher component costs and a need for electrical current to power POE devices.

 

PON systems consist of conversion equipment on both ends of a fiber run to convert electrical data signal to light and vice versa because computers and networking equipment can only interpret electrical data signals.  In the past, the signal conversion equipment was cost-prohibitive for a hotel project.  As recently as 2 years ago, the units required to convert the data stream from fiber back to copper cable at the guestroom were 3 times the cost that they are today. Multiply by 200, 500, or 1,000 guestrooms and it is easy to see how this cost alone prevented serious consideration of fiber to the guestroom.  Today, due largely to the popularity of PONs in the domestic and international markets, the cost of conversion components for a PON is comparable to those used with a copper Ethernet system.

An additional use of copper cable in the infrastructure is to provide power for any low voltage devices located in the guestroom.  The current solution is POE (Power Over Ethernet), either Cat 5e or Cat 6 cable, which is capable of delivering data and power (and increasingly IP voice).

Addressing the POE requirements with a PON system remains a challenge. However, composite fiber products that incorporate power cables within a common cable along with fiber strands are under development and may provide the means of delivering the required power to end devices.

In recent years, the design of the technology infrastructure has often employed a fiber backbone leading into and out of an MDF room.   The MDF room (Main Distribution Frame) is the main technology room for the building and is often referred to as the telecom room, server room, or communications room.  An IDF (Intermediate Distribution Frame) is a room located near the guestrooms (or area) that it serves for power, data and voice.  In the IDF, a data switch is used to convert the fiber back to copper. The copper then runs from the IDF to each guestroom.  The ‘Fiber to the Guestroom’ initiative involves bringing the fiber from the MDF all the way to each guestroom.   In many cases, this can eliminate the need for IDF rooms, saving on power and HVAC construction costs.  It also frees that space for other uses, as well as reducing conduit/pathway requirements.

 

Considering the dramatic fall in component costs, the cost/benefit of fiber to the guestroom is rapidly becoming a viable technology infrastructure solution for consideration.

Now that fiber to guestroom is becoming financially viable, there are a number of issues that warrant consideration when designing a GPON. Vendor acceptance, the placement of splitters, cabling pathways, end-user bandwidth budgets, and installation and implementation practices are just a few topics requiring coordination, design, and planning efforts.

HTNG

HTNG is seriously discussing this shift in technology infrastructure design. As a recognized voice of the global hotel community, their evaluation and recommendations shall go a long way toward the acceptance of GPON in hotels in the foreseeable future.

by Jeff Cook, RCDD

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