Reliability versus Cost in Next Generation Optical Access Networks

The ever increasing demands of Internet users caused by the introduction of new high bandwidth applications and online services as well as the growing number of users and devices connected to the Internet, bring many challenges for the operators, especially in the last mile section of the network. Next generation access architectures are expected to offer high sustainable bandwidth per user. They also need to support a much larger service areas to decrease number of current central offices and hence potentially save the network expenditures in the future. Obviously, it requires high capacity and low loss transmission and optical fiber technology is the only future proof candidates for broadband access. Although this technology has already been widely deployed in the core networks, it is hard to use the same expensive devices made for core segment to solve the last mile bottlenecks, due to the low number of users sharing the network resources (and deployment cost). Therefore, the next generation optical access (NGOA) networks need to be designed with consideration of cost efficiency in the first place. Network reliability is also turning to be an important aspect for the NGOA networks as a consequence of long reach, high client count and new services requiring uninterrupted access. Consequently, new architectures not only need to be cost efficient but also they should fulfill the increasing reliability requirements. Although several NGOA alternatives have been proposed in the literatures, there is not yet an agreement on a single architecture. As described earlier, network expenditure and reliability performance are the two main factors to be considered. Therefore, this thesis concentrates on finding a suitable alternative for future broadband access by evaluating the reliability performance and total cost of ownership for several NGOA candidates. In particular, in this thesis we analyze the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by the provided survivability mechanism. First, we identified the suitable NGOA candidates by comparing two main groups of optical access networks, namely passive optical networks (PONs) and active optical networks (AONs), in terms of cost, reliability performance and power consumption. The initial results have shown that wavelength division multiplexing PON (WDM PON) is the most promising alternative for the NGOA networks because of its high potential