 cable TV company) or even a competitor owns the right of way of the cable route or right of entry for the premises needed to house transmission equipment. For these reasons, the brute-force deployment of additional fiber is often somewhat of an impractical or last-resort solution for many carriers for both the long haul and the metro access/metro core space. Higher-Speed TDM-Deploying STM-64/OC-192 or 10 Gbps As indi- cated earlier, STM-64/OC-192 is becoming an option for carriers seeking higher capacity. However, there are significant technical issues surround- ing this solution, restricting its applicability. The majority of the existing fiber plant is single-mode fiber that has high dispersion in the 1,550-nm window, making STM-64/OC-192 transmission difficult to achieve reliably. In fact, dispersion has an effect that is 16 times greater with STM-64/OC- 192 equipment than with STM-16/OC-48. As a result, effective STM-64/OC- 192 transmission requires either some form of dispersion-compensating fiber or entire new fiber builds using nonzero dispersion-shifted fiber (NZDSF). Newer fiber can also be 50 percent more expensive than tradi- tional single-mode fiber, impacting the $70,000 per mile just cited. Traditional SONET Architectures Polarization mode dispersion (PMD), which impacts the distance a light pulse can travel without signal degradation, is of particular concern for STM-64/OC-192. As transmission speeds increase, dispersion problems grow significantly, thereby reducing the distance a signal can travel; this is a major concern in long-haul applications. Specifically, PMD seems to limit the reliable reach of STM-64/OC-192 to about 50 miles on most embedded fiber (see Figure 3-4). Although there is debate within the industry over the extent of PMD problems, some key issues are known: PMD is particularly acute in the conventional single-mode fiber plant that comprises the vast majority of the existing fiber plant as well as in aerial fiber. PMD varies significantly from cable to cable and is also affecte