Topology optimization for hybrid optical/wireless access networks
Introduction
The issue of providing effective access solutions to residential users is attracting increasing attention from different actors like service providers, commonalities, and academia. Indeed, in the last ten years, the quality of experience requested by residential users has incredibly increased (think of the quadruple play services), thus challenging the architectures of the deployed metropolitan access networks. To this extent, even if most of current access networks are mainly based on copper, optical technology is gauging momentum as an effective way to bring bandwidth to the final users. Among optical network architectures, Passive Optical Networks (PONs) are currently being deployed in many metropolitan environment, due to their favorable features in terms of offered bandwidth, robustness and maintainability.
On the other side, in many cases it is not possible or cost effective for the operator to reach every single residential user with the fiber, and consequently some type of connectivity extension must be provided through other communication technologies. In this scenario, the recent progresses in the field of wireless technologies have boosted the adoption of wireless access networks to reach the final residential users with cost effective, flexible and ubiquitous network deployments. As a consequence, it is straightforward to envision the use of Hybrid Wireless–Optical Broadband Access Networks (WOBANs) for “covering” metropolitan-scale areas, having desirable features in terms of provided bandwidth, deployment and maintenance costs.
To fully unleash the potentials of WOBAN architectures, several technical challenges have to be addressed and resolved, including the QoS management across the wireless/optical boundary [1], [2], the routing in the hybrid architecture [3] and the overall network management. Several testbeds have been recently developed to evaluate proposed algorithms and protocols [4], [5], [6]. Moreover, effective methods are needed to plan and optimize the WOBAN topology for two main reasons: first, the topology itself may have a huge impact on the overall “quality” of the network (both on the end user’s side, quality of service, and on the operator’s side, deployment cost); second, network deployments can involve hundreds of devices (optical and wireless), thus manual tuning is very unpractical and automatic topology planning and optimization tools are required.
In this work, we address the issue of designing the topology of a WOBAN composed by a Ethernet-based Passive Optical Networks (EPONs), which can be extended through a Wireless Mesh Network (WMN) operated by IEEE 802.11 and/or IEEE 802.16 standards. In details, we develop a complete mathematical programming model for the automatic planning of the entire WOBAN topology with the objective of minimizing the overall deployment costs, while accounting for the specific traffic requirements of the residential users, and the specific features of the technological components.
The main contributions of this work are:
- •
A complete optimization framework for planning and dimensioning WOBANs. Solved to the optimality, it selects the best network devices to be installed, their positions and the configuration of the entire network.
- •
The inclusion of a multi-hop network paradigm in the wireless domain.
- •
The possibility of selecting between IEEE 802.11 and IEEE 802.16 devices for the wireless domain. The outcome shows which is the best technology to deploy in each part of the network according to technical characteristics, traffic distribution and device costs.
To the best of our knowledge, this is the first work on WOBAN planning accounting for multi-hop wireless extensions to the optical segment, further considering the choice between different wireless technologies with different features and constraints (IEEE 802.11 vs. IEEE 802.16).
The remainder of the paper is structured as follows: Section 2 overviews the related work in the field, Section 3 overviews the main building blocks of the reference WOBAN architecture, and provides the problem statement. In Section 4, we introduce the optimization model for WOBAN planning and comment on the corresponding formulation. Section 5 reports on the performance evaluation carried out to assess the quality and the utility of the proposed optimization model. Finally, concluding remarks are given in Section 6.
Section snippets
Related works
Previous work on Hybrid Optical/Wireless Access Networks can be categorized into three main areas: contributions on the general architecture of hybrid optical/wireless networks, contributions on protocol-oriented aspects of routing and channel assignment, and contributions on hybrid network planning and optimization.
Referring to the first class, architecture papers aims at analyzing the challenges to be faced when deploying such hybrid networks, deriving general guidelines on the best type of
Background and problem statement
The problem addressed in this paper is the planning of a WOBAN considering both optical and wireless realms, where the former consists of a EPON and the latter can be managed via IEEE 802.11 or IEEE 802.16 devices. Given a traffic demand distributed over a deployment area, we want to design the whole backbone infrastructure delegated to collect traffic. The backbone consists of a metropolitan Central Office (CO) from where optical fibers depart in order to feed wireless access points, both IEEE
Problem formulation
We consider a deployment area where traffic source points, named test points, are placed. Each test point can represent a single residential user or a centroid of a discrete/continuous traffic distribution according to the desired planning scenario. The set of test points is denoted by . Similarly, IEEE 802.11 devices (MRs) and IEEE 802.16 devices (RSs) can be installed in discrete sets of candidate sites and , respectively. Due to wiring issues, ONUs can be placed only in a limited
Numerical results
We analyzed solutions obtained by solving to optimality the proposed formulations. This allows us to highlight the effects on the solutions when some important design parameters change, as we show in Section 5.1, or when more OLT site locations are available, as reported in Section 5.2. Then, we give some commented snapshots of planned networks for a couple of interesting scenarios under different traffic conditions in Section 5.3.
Instances are solved running the state-of-the-art solver CPLEX
Conclusion and future work
In this work, we have addressed the issue of designing the topology of hybrid optical/wireless access networks, which are increasingly deployed to provide residential coverage to metropolitan areas. Mathematical programming formulations have been proposed to automatically plan the topology of hybrid network architectures based on Ethernet-Passive Optical Networks (EPONs) and Wireless Mesh Networks (WMNs) operated according to the IEEE 802.11 and IEEE 802.16 standards. The proposed formulation
Acknowledgments
This work has been partially supported by the European Network of Excellence EuroNF, in the framework of the specific joint research project FI-WI – Future Integrated Access Architecture Based on Optical and Broadband Wireless Technologies.
Ilario Filippini received the B.S. and M.S. degrees in Telecommunication Engineering from the Politecnico di Milano, Italy, in 2003 and 2005, and a Ph.D in Information Engineering in April 2009 from the Politecnico di Milano. From February 2008 to August 2008 he has been working as a visiting researcher at the Department of Electrical and Computer Engineering of The Ohio State University in Columbus (OH). He is currently a PostDoc researcher of the Electronics and Information Department of the
References (35)
- et al.
Optimization models and methods for planning wireless mesh networks
Computer Networks
(2008) - et al.
Toward QoS protection in ethernet passive optical networks: challenges and solutions
IEEE Network
(2007) - D. Remondo, M. Nunes, S. Sargento, M. Cesana, I. Filippini, J. Triay, A. Agusti, M. De Andrade, L. Gutierrez, S....
- A. Reaz, V. Ramamurthi, S. Sarkar, D. Ghosal, S. Dixit, B. Mukherjee, CaDAR: an efficient routing algorithm for...
- J. Hu, D. Qian, H. Yang, T. Wang, S. Weinstein, M. Cvijetic, S. Nakamura, Triple play services over a converged...
- et al.
Hybrid architecture and integrated routing in a scalable optical–wireless access network
IEEE Journal of Lightwave Technology
(2007) - et al.
Hybrid wireless–optical broadband access network (WOBAN): prototype development and research challenges
IEEE Network
(2009) - K. Katrinis, A. Tzanakaki, S. Dweikat, S. Vassilaras, R. Nejabati, D. Simeonidou, G. Zervas, Backhauling wireless...
- et al.
Interoperability of GPON and WiMAX for network capacity enhancement and resilience
Journal of Optical Networking
(2009) - Z. Zheng, J. Wang, J. Wang, A study of network throughput gain in optical–wireless (FiWi) Networks Subject to...
A novel delay-aware routing algorithm (DARA) for a hybrid wireless–optical broadband access network (WOBAN)
IEEE Network
Passive optical network planning in local access networks – an optimisation approach utilizing genetic algorithms
BT Technology Journal
Cited by (19)
A survey on access technologies for broadband optical and wireless networks
2014, Journal of Network and Computer ApplicationsCitation Excerpt :The spectral efficient OFDM transmission provides an effective solution to eliminate ISI caused by dispersive channels (Pham et al., 2012). Most of the proposed WOBANs have been designed, and implemented based on transmission of single wireless signal over fiber by using either of the aforementioned schemes BBOF or ROF (Ghazisaidi and Maier, 2011; Sarkar et al., 2007; Shaw et al., 2007a; Shaddad et al., 2011a; Chowdhury et al., 2009; Filippini and Cesana, 2009; Reaz et al., 2008). To carry out a spectral efficient WOBAN, the wireless MIMO OFDM technique has been implemented (Shaddad et al., 2012).
Spectral efficient hybrid wireless optical broadband access network (WOBAN) based on transmission of wireless MIMO OFDM signals over WDM PON
2012, Optics CommunicationsCitation Excerpt :The WOBAN is proposed to provide blanket coverage of broadband and flexible connection for end-users. Most of the existing works, based on performance evaluation are concerned on network layer aspects [1–4]. The technical and deployment considerations of the hybrid WOBAN are discussed such as network setup, network connectivity, and fault-tolerant behavior of the WOBAN [1].
Analysis of physical layer performance of hybrid optical-wireless access network
2011, Optics CommunicationsCitation Excerpt :The performance of hybrid network protocols of a programmable and configurable WOBAN is demonstrated and analyzed for several typical applications such as data transfer, voice, and video over WOBAN [7]. The overall WOBAN topology in terms of link capacity, available topologies, deployment cost has been recently optimized by using a mathematical programming model to get consistent and effective hybrid networks [8]. Shaw et al. [1] proposed an integrated-routing algorithm to achieve load balancing on the hybrid scalable optical–wireless access network which consists of reconfigurable optical backhaul and WMN and aims to provide a broadband, ubiquitous, and blanket-coverage access service.
Optimization of passive optical network planning
2011, Applied Mathematical ModellingCitation Excerpt :The same authors presented in 2009, a set of heuristic algorithms to optimize the location of multiple optical network units in a hybrid wireless-optical broadband access network. Filippini and Cesana [11] developed mathematical programming model for the planning of the entire hybrid wireless-optical broadband access networks topology with the objective of minimizing the overall deployment costs. Kim et al. [12] focused on the design of the distribution network arising from the deployment of fiber-to-the-home PONs, They developed two MIP models and a heuristic procedure for finding the optimal placement of splitters.
Ilario Filippini received the B.S. and M.S. degrees in Telecommunication Engineering from the Politecnico di Milano, Italy, in 2003 and 2005, and a Ph.D in Information Engineering in April 2009 from the Politecnico di Milano. From February 2008 to August 2008 he has been working as a visiting researcher at the Department of Electrical and Computer Engineering of The Ohio State University in Columbus (OH). He is currently a PostDoc researcher of the Electronics and Information Department of the Politecnico di Milano. His research activities include networking and optimization issues, in particular wireless multi-hop network planning, optimization and protocol design. He is a regular reviewer of the main journals in the networking area. He is a member of the IEEE Communication and Computer Societies.
Matteo Cesana received his MS degree in Telecommunications Engineering and his Ph.D. degree in Information Engineering from the Politecnico di Milano in July 2000 and in September 2004, respectively. From September 2002 to March 2003 he has been working as a visiting researcher at the Computer Science Department of the University of California in Los Angeles (UCLA). He is now an Assistant Professor of the Electronics and Information Department of the Politecnico di Milano. His research activities are in the field of performance evaluation of cellular systems, ad hoc networks protocol design and evaluation and wireless networks optimization. He is an editor of Ad Hoc Networks Journal (Elsevier), and he has served in the technical program committee of several international conferences. He is a regular reviewer of the main journals in the networking area. He is a member of IEEE Communication and Computer societies.