Summary

As candidates for RBB networks, FTTC and FTTH seem to represent the best of all possible worlds. They hold out the promise of being full-service networks, the elusive single entity that can provide all the high speed and traditional services that consumers are likely to want delivered to their homes. These technologies are also the least established and applied at this point in history, so predicting their future is difficult. Table 5-3 summarizes the challenges and facilitators of FTTH.

FTTx has the potential of the highest bandwidth for two-way traffic, with potentially higher QoS to consumers. The benefits to carriers are reduced operational costs, reduced long-term life cycle costs, and differentiation from cable services.

Fiber is brought closer to the home by HFC, xDSL, and FTTC. FTTH stands to benefit from this progress, but interestingly and ironically, it may be that the last few hundred meters may not be fiber at all. It may not be traversed by coaxial cable or twisted pair either. That last few hundred meters may well be traversed by wireless means, which also benefit greatly from the distribution of fiber farther into the neighborhood. As the distances between the residence and the ONU shrinks, wireless will be capable of offering clear signals at low infrastructure costs. The following chapter discusses the final access network, the wireless local loop.

Table 5-3. Challenges and Facilitators for FTTx and RBB
Issue Challenges Facilitators
Media Increased fiber distribution entails digging; requires precision handling, equipment, and training. Fiber is being installed anyway and will reduce life cycle maintenance costs for carriers.
Modulation schemes QAM 16 and QPSK need to operate at high speeds. Digital modulation technique for fiber is simple On/Off keying.
Noise mitigation Higher speeds create little tolerance for line impairments. Fiber is more immune to external noise.
Signaling Switched video signaling must mimic home channel surfing. FTTx sessions don't connect through a voice switch, thus reducing signaling through the voice switch. PON is passive, not requiring active signaling.
Data-handling capabilities Speed is less than cable in the forward path for all but dedicated FTTH. Good return path service enables reliable interactive service with known QoS.
Standards Standards are lagging behind more established technologies. In particular, standards for end-to-end service architectures are unresolved. VDSL standards are in flux. Substantial agreement on important PHY-level issues exists. Relatively few bodies are deliberating FTTx specifications, with a relatively little chance of conflict.
Business/Financial CPE and infrastructure costs are high.

Telcos do not have a good track record at rolling out high-speed services.

Questions remain over how to transition customers' home wiring. 		Telco costs are reduced for provisioning, powering, and maintenance.

The data burden on voice switches is reduced.

The maintenance budget can be used for certain upgrades.

There is a logical transition plan from ADSL through FTTC to FTTH.
Market Customers may not want full-service networks.

Customers may be satisfied with HFC and xDSL.

Support for broadcast video over switched networks has been untested. 		The greatest return path bandwidth exists. Enough bandwidth exists to support customers' Web sites.
Regulation Mechanisms to support law enforcement wiretapping have not yet been resolved (FTTH).

It is uncertain whether regulation will force carriers to provide network powering to the ONU.

Unbundling requirements and open access requirements are unclear. 		Possible relief from powering requirements will arise if Universal Service can be provided via wireless telephony.

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