Developing the next-generation optical access network architectures

– I am from Tehran, the capital of Iran. I got my Bachelor’s degree in Electronic Engineering from Iran University of Science and Technology (IUST) in Tehran. After two years of working in Tehran, I came to Stockholm for my Master’s studies and by the end of 2010, I received my Master’s degree from KTH with specialization in Internetworking.

– My PhD title is “Reliability versus Cost in Next Generation Optical Access Networks”.

I found this topic very interesting and demanding. I started my studies in the framework of the OASE project (FP7 EU project in collaboration with well known European telecom operators and vendors such as Deutsche Telekom and Ericsson) aiming to assess and develop the next-generation optical access (NGOA) network architectures for the “2020” timeframe, focusing particularly on European requirements. It is nice to see that your research results are going to be deployed and influence the real network infrastructure and future generation of the internet. 

– 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 access section of the network. Next generation access architectures are expected to offer high sustainable bandwidth of 1Gbps per user. Therefore optical fiber technology is the only future proof candidates for broadband access. The access network is shared among fewer users compared to the core and aggregation segment which makes the last mile section of the network very cost sensitive. Hence Next Generation Optical Access (NGOA) networks should be designed with cost efficiency in mind 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 counts 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. Therefore, my research 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, we analyzed the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by our proposed 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 capacity, low cost and power consumption. So we continued our studies by investigating WDM based PON architectures regarding their cost and reliability performance. Our results confirmed that hybrid WDM/TDM PON (HPON) is the best alternative for the NGOA networks. In summary, we have shown that HPON is able to fulfill the main NGOA requirements such as high bandwidth per user, large coverage and client count. The work carried out in the thesis has proved that it can also offer high reliability performance while keeping the network expenditures at an acceptable level. HPON also has low power consumption and high flexibility in resource allocation, which makes it a winning candidate for the NGOA. Therefore, HPON is a promising architecture to be deployed as NGOA network in the near future considering the fact that components are soon to be available in the market.

– I will continue working on the NGOA network solutions with the focus on optimization of network structure and architectures. The long reach characteristic of optical fiber technologies allows operators to decrease the number of central offices in the access network and eliminate the aggregation section as much as possible referred to node consolidation. The optimized number and location of the new central offices as well as the possible cost saving caused by node consolidation is an important research topic for both industry and academic and will be my future direction for the rest of my PhD studies.

You can find Mozghan's licentiate thesis here .