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April 2001 Issue
Open Access: Hybrid Fiber/Coax Management, Part 4
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Operators need to prepare to manage outages, spectrum and capacity before open access begins.

Hybrid fiber/coax (HFC) management deals with the care and feeding of perhaps the most critical component of the broadband transport—the last mile. Also called the local loop, this portion of the transport permits:

• Access for content providers to reach broadband customers and broadband consumer devices.
• Connectivity for content consumers to communicate with one another.
• Access for content consumers, such as TVs, telephones and computers, to reach an open market of content providers.

The fact that so many providers and consumers are crowded on either end of the broadband transport raises several very important management concerns.

Managing broadband transport outages

Broadband transports—including twisted pair (copper), coaxial cable, fiber optics, wireless transmitters and receivers and satellite—have one thing in common. That is, they all have at least one single point of failure somewhere in the delivery of services to their customers. Single points of failure are necessary to keep costs down while delivering the best possible quality of service (QoS) to customers. The fact that all these technologies have at least one single point of failure can lower expectations of the service and level the playing field on which they all compete for customers.

The broadband operator compensates for these single points of failure by employees who oversee the health of broadband transport. These employees work in the network operations center that watches various monitoring systems, oversees events, dispatches field employees to resolve the problem and keeps interested parties informed of events.

These workers also repair and replace defective lines or equipment. An event could be anything from a zero-outage service item, such as the replacement of a redundant power supply gone bad, to a reactionary correction of an outage on the broadband transport. Manual efforts may actually benefit broadband operators because they are cheap and easy ways to train employees on how they should handle events. Employees should use common sense and experience.

For example, a computer can’t determine that something is wrong when several calls come in from customers residing in a particular area. Only an individual could relate such events to a potential outage. Computers don’t possess this experience or common sense and, as a result, are left to handle more routine and well-known events.

Unfortunately, manual intervention into broadband management may be detrimental. Humans, while resourceful, are prone to make mistakes. Stress, as well as inexperience, can teach expensive lessons to a broadband operator and its employees. Consequently, broadband operators have become increasingly cautious about making hasty changes to their complex transports. In addition, they need to be more cautious since these transports now carry multiple services, each with its own operational criteria. Trying to resolve one problem in them could in effect render the other services inoperable. In no other issue is this as important as in the case of open access.

Open access demands a level of management beyond most broadband operators. Never before has the importance of knowing the operational health of their transport been so important. Yet today’s broadband operators are ill equipped to manage their transport down to the end-of-line (EOL).

The EOL is traditionally associated with copper-based transport media and it defines a location where the signal terminates. EOL could be a customer home or even a junction where customers could connect. Some broadband operators have been able to deploy EOL monitoring devices with complete transport visibility, most have not been able to because of the expense.

Instead, operators only monitor major portions of the transport—leaving the remaining portions, which can represent anywhere from 30 percent to 50 percent of their customers, invisible. The invisible portions must rely on the operator’s existing and even potential customers to alert them of potential outages.

Relying on subscribers to report outages is further challenged by open access. Many services created as a result of third parties, not the broadband operator, may own or distribute open access. Confusion is likely to result in these instances. For example, if the service doesn’t work, whom does the customer call—the operator, the Internet provider, or the service provider? What’s more, how can an operator manually determine if something is wrong on invisible portions of its transport when customer calls go somewhere other than its call center?

The answers may lie in technologies that provide more visibility on an operator’s transport. These technologies include non-invasive network management, EOL devices and possibly even intelligent use of customer devices, such as customer premises equipment (CPE), cable modems and set-top boxes.

Managing broadband transport capacity

When a telephone company designs a phone system to provide service to a number of customers, it rarely supports a scenario allowing every residence to use its service at the same time. Although theoretically it is possible to provide such capacity, phone systems typically don’t dedicate the resources it would require to support this scenario. Instead, telephone companies maintain support for a portion (25 percent to 40 percent) of their customers to use the service at the same time. This percentage typically covers peak usage but not much more—again so as to conserve resources and keep down costs.

This conservation of resources is a means of managing an operator’s transport—something everyone in the business of providing a service worries about. Managing capacity allows the greatest distribution of service at the least cost. Failure to manage capacity requires huge expense with little, if any, regard to normal usage patterns.

To effectively manage capacity, continually keep tabs on the usage of the transport. Because the transport is a finite medium, it must be closely monitored to ensure that traffic does not reach capacity even during peak times. It also must be flexible enough to increase capacity where it is needed.

The advent of QoS presents some interesting challenges for capacity management—especially in the case of open access. QoS provides dedicated capacity or bandwidth between a service provider and the customer.

For example, QoS provides dedicated capacity so that a customer may place a phone call over broadband and other services do not have to compete for finite capacity on the transport. While a phone call is relatively small, representing only a fraction of the capacity available, using QoS increasingly to reserve portions of a finite resource will become a challenge for capacity management because it is unlikely that the whole broadband transport will be made available. Again, as with telephone company phone systems, broadband operators must maintain support for a percentage of their customers to use QoS services as well as support other services that run on the network.

In open access, operators could quickly lose touch with the types of services running over their broadband transport. Some services may even use the same QoS capacity reserved for telephone or video-on-demand (VOD) to ensure their service does not encounter any roadblocks during delivery.

If an operator does not monitor its capacity it could even face legal problems, such as if limited capacity blocked 911 calls. Open access also could quickly usher in new services that demand even more capacity. If these services push maximum capacity, other services could be affected.

Managing capacity also is a concern outside the HFC network where the routing of packets can quickly change from one Internet service provider (ISP) to another, which could go against previous capacity planning. These swings in customer choice from one ISP to another may be the result of circumstances such as mergers or problems that force customers to choose a new ISP. Because these swings in choices cannot be foreseen, it is highly unlikely that the current capacity is ready for change.

The success of capacity management is determined by an operator’s ability to oversee transports in terms of how much bandwidth and the types of services used. This requires operators to use bandwidth-analysis tools, keep tabs on services under development, provide the information needed to stay ahead of future capacity needs and make the best use of resources.

Managing broadband transport spectrum

In the digital domain, several of these static things change. For example, a single compressed digital video channel requires about 1/12th the bandwidth of the same channel on analog. In addition, advanced technology allows up to 16 digital video channels within the space of a single analog video channel through the use of statistical multiplexing, or stat-muxing.

As a result, the concept of static frequencies reserved for specific services is becoming a thing of the past. In fact, managing available spectrum could be an operator’s ticket to optimizing its transport in a way that provides the capability to deliver additional services as they become available.

Stat-muxing potentially allows services such as video, data and voice to be combined in the most spectrum-friendly way possible. That way, QoS needs with voice, as well as some data services, could be used with the least amount of spectrum, using only what they need rather than the minimum defined by the QoS.

Open access will push today’s manual spectrum management to it limits as more and more ISPs and service providers obtain direct access to broadband customers. Because each ISP and service provider will bring something unique to the table, these value-added services will provide broadband customers with more service options including a la carte services. As a result, the spectrum required to run all of these services will require more flexibility than manual static allocation frequencies can support.

The answer to this growing need for spectrum is automation. Essentially, open access will require dynamic spectrum allocation to provide bandwidth on-demand for the growing number of services offered to customers.

Bruce Bahlmann is a contributing editor to CT. He may be reached at .

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