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Progress beyond the State-Of-the-Art

CONFES aims to transform the contemporary architecture of wired-wireless access and metro networks into an integrated network infrastructure with superior performance. The CONFES convergent network architecture will advance the state-of-the-art through:

  • Defining and optimizing service provisioning mechanisms for the wireless and optical network segments, including intra-segment (i.e. efficiently plan and dynamically allocate resources per segment) as well as inter-segment (i.e. optimally allocate end-to-end network resources) mechanisms, supporting the requirements of fast network reconfiguration in order to:

    • adapt to temporal and spatial fluctuations in traffic demand (i.e. supporting capacity migration) and

    • restore service provisioning in case of network failures without service interruption.

  • Supporting seamless service mobility and Media Independent Handover.
Existing solutions to wired-wireless network integration are based on independent technologies, each of which is optimized for a specific part of the network rather than the end-to-end network performance, with effects on performance, complexity and processing power. The proposed CONFES architecture is aimed at enhancing the effectiveness of PONs in terms of resource allocation, dynamic bandwidth allocation in real-time and network efficiency enhancement through statistical multiplexing.
What is missing from existing solutions is the “tool set” that will enable what is called in the context of the CONFES vision capacity migration. Capacity migration -for example in between nodes on the same network- can be triggered by statistically unlikely user behavior, like massive spatial redistribution of user calls, rare events or even user driven decisions for handover based on specific quality of service criteria, etc. Such an example is depicted in the figure below. However, in the context of next generation networks such phenomena will constitute expected networking conditions, when applications like cloud computing, multimedia peer-to-peer networks and other distributed applications coupled with high user mobility are introduced in the offered service bundles.

While several standardization bodies like 3GPP, ITU, ETSI, FSAN etc. have established working groups in order to study and introduce interoperable protocols and interfaces, there are still several open issues that will be addressed by CONFES, related to the optimization of the above scenario including the following:

  • Multi-technology access based on service related criteria (connection quality, cost, etc.) addressed in the past only in the wireless domain. 

  • User mobility management based on quality of service criteria in networks with a large number of Wireless Access Points - which are necessary to achieve dense coverage (smaller cell dimensioning).

More specifically, concerning the state-of-the-art of individual transmission technologies (in particular optical networks) to be exploited within the context of the project, recently, both ITU and IEEE have produced PON standards operating at Gb/s line rates and optimizing the transport of packet-based traffic. In January 2003, the GPON (Gigabit PON) standards were ratified by ITU-T and were included in the G.984.x series of ITU-T Recommendations. At the same time IEEE, through the activities of Ethernet in the First Mile (EFM) 802.3ah group, has standardized a Gigabit Ethernet-friendly technology called Ethernet PON (EPON), with the objective to exploit the economies of scale that the dominance of Ethernet has generated. The IEEE 10-Gigabit EPON (10GEPON) task group (802.3av) is on track to move the standardization process to the next step, whereas an ITU G-PON amendment to 10Gbps rates and above (NG-PON) is under study.
Long Reach (LR) PONs, although not yet commercially available, appear to be a very promising solution that is technically viable. It may be possible to offer the ability to serve as many as 1000 customers over a distance of 100 km. At the same time, beyond the single wavelength transmission, both GPON and EPON already make some use of wavelength division multiplexing (WDM). On the other hand, metro and long-haul networks make extensive use of WDM.
It is among the intentions of CONFES to provide an extended reach access/metro network segment (100-200km), which integrates easily with optical access technologies (such as the PONs addressed by the project), and will support very high overall capacity. CONFES will investigate potential architectural enhancements adopting these technologies, in order to offer the required aggregation and connectivity with the wireless network domain (backhauling).

Specifically, as shown in the above figure, CONFES will evaluate novel long-reach (LR) hybrid Passive Optical Networks that will facilitate efficient backhauling for new types of both fixed and mobile services with increased requirements in terms of mobility and service portability. The network evolution, that will be studied in CONFES, will extend to address network scalability and upgrades, employing reconfigurable/active components at the RN (potentially based on λ-agile switches), and wavelength agility (through filters, tunable transceivers) at the ONU side.
CONFES aims to exploit mature photonic system technologies and evaluate throughout the lifetime of the project the ongoing developments in this area. Technologies of interest include network architectures featuring network reconfiguration to support capacity migration (described above), like the example described in the figure below.