Mozhgan Mahloo | KTH Royal Institute of Technology (original) (raw)

Papers by Mozhgan Mahloo

IEEE Communications Magazine

ABSTRACT Individual users and enterprises are increasingly relying on the access to internet serv... more ABSTRACT Individual users and enterprises are increasingly relying on the access to internet services and cannot accept long interruption time as easily as before. Moreover, the main characteristics of next generation optical access (NGOA) networks, such as long reach and large number of users per feeder line, turn the network reliability to an important design parameter to offer uninterrupted service delivery. In this regard, protection mechanisms become one of the crucial aspects that need to be considered in the design process of access networks. On the other hand, it should be noted that not all the users can afford to pay a high extra cost for protection and hence it is important to provide resilience in a cost-efficient way. A passive optical network (PON) combining wavelength division multiplexing (WDM) and time division multiplexing (TDM) technologies, referred to as hybrid WDM/TDM PON or HPON, is one of the most promising candidates for NGOA networks due to its ability to serve a large number of subscribers and to offer a high capacity per user. For these reasons in this paper, we propose HPON architecture offering different degrees of resilience depending on the user profiles, i.e. partial and full protection for residential and business access, respectively. Besides, the investment cost of providing resilience for the proposed schemes is investigated considering various protection upgrade road maps. Our results confirm that protecting the shared part of network with a large number of users is required in order to keep the failure impact at an acceptable level, with less than 5% increase of the investment cost compared to the unprotected case. Meanwhile, the proposed end-to-end protection for the business users considerably reduces the risk of service interruption for this kind of demanding users without a need for duplicating the deployment cost of an unprotected connection. Furthermore, a sensitivity analysis is performed to investigate the impact of changes in business user percentage and protection upgrade time on the deployment cost. The results may be used as an advice for a cost-efficient deployment of reliable fiber access networks.

Network Architectures, Management, and Applications IX, 2011

ABSTRACT In this paper, we investigate the capital and operational expenditures for two next gene... more ABSTRACT In this paper, we investigate the capital and operational expenditures for two next generation optical access (NGOA) networks based on wavelength division multiplexing (WDM) technology in dense urban areas. It is shown that with a proper fiber layout design, minor extra investment for protection of NGOA networks can make a significant saving on failure related operational cost.

2012 IEEE International Conference on Communications (ICC), 2012

Hybrid WDM/TDM Passive Optical Network (PON) is a promising candidate for next-generation optical... more Hybrid WDM/TDM Passive Optical Network (PON) is a promising candidate for next-generation optical access (NGOA) solutions as it is able to offer a high splitting ratio and consequently achieves a relatively low cost and power consumption on a per-user basis compared with other NGOA architectures. On the other hand, the end users require a certain level of connection availability while the operators need to reduce the failure impact (i.e. to avoid a huge number of end users being affected by any single failure). Therefore, by evaluating the connection availability and failure impact robustness we identify the most efficient parts to provide resilience in a hybrid WDM/TDM PON from an operator and an end-user perspective. Then, we select the appropriate protection schemes to construct some novel reliable architectures and analyze their reliability performance in urban and rural scenarios. In this way, this paper provides a comprehensive insight into the most relevant protection mechanisms for hybrid WDM/TDM PONs.

Journal of Optical Communications and Networking, 2013

ABSTRACT Evolution of optical access networks promises to bring higher bandwidth to more customer... more ABSTRACT Evolution of optical access networks promises to bring higher bandwidth to more customers. However, this evolution toward so-called next generation optical access (NGOA) networks also introduces additional challenges that operators and/or vendors have to address: how to properly estimate and compare different NGOA architectures and their evolutionary paths in terms of their economics. Calculating the total cost of ownership (TCO) for NGOA networks is a very complex target as it needs to involve good knowledge of the technology, the existing network infrastructure, and any migration-related processes. In this paper a complete methodology is presented for evaluating the TCO of the migration toward a NGOA network. It contains a detailed description of which key aspects have to be considered, which processes they affect, and how they are translated into costs in a logical manner. Finally, it also shows how this methodology has been applied to particular selected cases and how it gives a detailed view of all costs involved in migration. This approach opens up opportunities to cooperate in techno-economic research using it as a base. Both operators and vendors can also utilize this approach to get a useful economic background of their future investments and potential sales.

2014 IEEE International Conference on Communications Workshops (ICC), 2014

Wireless heterogeneous networks (HetNets) based on small cells are a cost and energy efficient al... more Wireless heterogeneous networks (HetNets) based on small cells are a cost and energy efficient alternative to provide high capacity to the end users. On the other hand, the cost and energy consumption of backhaul network aggregating data traffic from a large number of base stations may limit the benefits brought by the use of small cell. In HetNet deployments it becomes thus essential to be able to assess the total cost of ownership (TCO) of the backhaul network. This paper presents for the first time a comprehensive cost evaluation methodology to compute the TCO of mobile backhaul networks. The presented model can be instrumental to identify the most critical cost drivers in the backhaul networks and to have a better understanding of the backhaul TCO dynamics when small cells are deployed. The proposed TCO model is then used in a case study where two technology options for the backhaul are considered, i.e., microwave and fiber. The results from the case study show how it is possible to identify the most critical cost factors, thus easing the way towards a cost efficient backhaul design strategy.

Network Architectures, Management, and Applications, 2011

Optical Switching and Networking, 2013

New technologies and advanced network devices make it possible to move towards high capacity acce... more New technologies and advanced network devices make it possible to move towards high capacity access networks able to satisfy the growing traffic demand. Wavelength division multiplexing (WDM) is considered as one of the promising technologies for the next generation access networks since it offers higher bandwidth and longer reach compared to the current technologies (such as time division multiplexing (TDM) based networks). However, the migration to a new technology is typically based on an overall techno-economic study which should assure the network operator that the new implementation is cost effective and profitable while able to provide the required services to the users. Another important aspect in the access network design is the network reliability performance, which can be improved by providing a certain level of protection for equipment and/or infrastructure with high failure impact ratio in order to prevent a big number of the users being affected by a single failure. The cost of protection should be carefully evaluated since providing the backup resources may be too expensive for a network operator.

Optical Switching and Networking, 2014

Active optical networks Peer to Peer traffic Locality of traffic Power consumption and power effi... more Active optical networks Peer to Peer traffic Locality of traffic Power consumption and power efficiency a b s t r a c t Video streaming and video-on-demand are gaining popularity nowadays which dictates a need of bandwidth upgrade for Internet users. Many next generation optical access network architectures have been proposed to meet high capacity requirement on a peruser basis. However, the capacity upgrade in access networks, may lead to a huge traffic growth in the aggregation/core network. One way to avoid this problem is to keep the traffic locally (i.e., inside the access network area) as much as possible. It can be obtained by using locality-aware peer-to-peer (P2P) applications for content distribution and has the potential to offload the core segment. However, various optical access network architectures accommodate the P2P traffic in different ways. Thus, it is important to study these differences in order to identify the best architecture option for capacity offloading in the core network, energy efficiency and network resource utilization. By deploying a proper architecture in the access segment along with an efficient traffic locality aware strategy, the extra investment and capacity upgrade of the expensive core network resources needed to support the future traffic expansion can be minimized. However, to the best of our knowledge this kind of assessment is so far not available. Therefore, in this paper, we analyze the efficiency of supporting locality-aware P2P video distribution algorithm in three main types of optical access network architectures, i.e., active optical network (AON), wavelength division multiplexing passive optical network (WDM PON) and time/wavelength division multiplexing PON (TWDM PON). Our goal is to provide important design guidelines for the next generation broadband access architectures, while minimizing the need for the core network upgrade. We obtain this objective by utilizing the unique characteristics of each access network architecture in accommodating P2P video delivery applications. We have done an extensive literature study and for the first time we have compared performance of these architectures with respect to the amount of the traffic on the links in different aggregation levels, power consumption taking into account sleep mode functionality at the user premises, and required switching capacity in the nodes. Our results reveal that both active and passive architectures have good ability to localize P2P traffic, whereas they show distinct performance with respect to the other aforementioned aspects. This is caused by the different number of aggregation levels, link capacity, and resource allocation protocols. Considering the overall performance evaluation, it is shown that TWDM PON is the most promising option for the future broadband access, where locality-aware P2P video distribution is applied, thanks to its low energy consumption and required switching capacity of the network equipment needed to deliver this service. This conclusion is against the general intuition because of the PON's centralized control plane and passive

IEEE Communications Magazine, 2000