Hagen Woesner

Traffic grooming in light trail networks

In todays WDM networks the dominating cost factor is the number of transceivers. Light trails have been shown to reduce the total number of wavelengths, however not necessarily the number of transceivers used in the network. Within this paper we explain two mechanisms that deal with reducing the total number of transceivers in light trail networks. While the first method - tune in light trails (TILT) - ensures that this number is at most the one of a corresponding lightpath network, traffic grooming can be applied in light trail networks as well to reduce the number of transceivers even further. Simulation results show that the TILT network has much better performance than the traditional counterpart, especially when the number of transceivers in the network is limited. Also the light trail network with grooming has better performance than that without grooming

Nomadic sensor networks

Wireless sensor networks (WSN) have been investigated in their various forms over the last years as they are considered to be a major step towards pervasive computing. Nevertheless, except for military applications WSNs can be found only as proof of concept. Within this paper we analyze the current situation and explain what we call the dilemma of WSN. We show the consequences of the various choices for the sensor node design and propose nomadic sensor networks as a way to introduce sensors into our everyday life in an incremental and cost-effective way. We show the general feasibility of this concept by presenting preliminary analytic and simulation based results, using a simple parking scenario for demonstration purposes.

Bidirectional light-trails for synchronous communications in WDM networks

This paper presents a novel solution of bidirectional high speed communications for IP traffic transport over WDM networks. Based on the observation of the bidirectional nature of traffic in the Internet bidirectional light-trails are proposed as an extension of the natively unidirectional light-trail concept. Specification of a synchronous protocol enables fairness in medium access and data delivery improving reliability of communications and enabling QoS support in WDM networks

OTDM light trail networks

Due to the limitation of the electrical port speed, current Ethernet switches can only run at most 10 Gb/s. In order to realize 100 Gb/s Ethernet switching, the OTDM technology can be exploited. OTDM lightpath network has the ability for 100 Gb/s Ethernet switching, however, more modulators need to be equipped in the transmitters, and only connections from the source node to its downstream nodes in a super lightpath can be realized. In this paper, the concept of OTDM light trail networks is proposed. Based on the light trail principle, which allows intermediate nodes to access the light trail, by using OTDM technology, the 100 Gb/s line speed can be realized without increasing the port speed or the number of modulators in the transmitters. One node structure for the OTDM light trail network is proposed and four methods for time slots assignment are classified. It is proved by numerical simulation that OTDM light trail networks can successfully increase the capacity of normal light trail networks. Compared with OTDM lightpath networks, cost can be saved and better performance can be obtained in OTDM light trail networks.

WiGEE: A Hybrid Optical/Wireless Gigabit WLAN

In this paper we propose a novel architecture integrating a fiber optic infrastructure with 60 GHz wireless transmission, capable of delivering a data rate up to 1 Gbps per cell in indoor environment. The system uses a hybrid WDM/TDM PON as the fixed infrastructure and the 60 GHz radio to provide the end user access and mobility. A centralized medium access control mechanism derived from IEEE 802.3ah is adopted for efficient channel access and bandwidth allocation. The use of standard components and the dynamic bandwidth allocation across wireless cells makes the system a strong candidate for future gigabit wireless LANs.

BIONETS: BIO-inspired NExt generation networks

The amount of information in the new emerging all-embracing pervasive environments will be enormous. Current Internet protocol conceived almost forty years ago, were never planned for these emerging pervasive environments. The communications requirements placed by these protocols on the low cost sensor and tag nodes are in direct contradiction to the fundamental goals if these nodes, being small, inexpensive and maintenance free. This situation needs therefore a radically different approach to communication in these systems, especially since pervasive and ubiquitous networks are expected to be the key drivers of the all encompassing Internet of the conaing decades. The fundamental disparity between the need for extremely dispensable, low cost devices, such as sensors or tags, and increasing communications load per device due to the presence of billions of nodes, that is creating an unbridgeable paradox, is therefore an insurmountable obstacle on the way to adoption when conventional networking architectures are being considered. Biological systems provide insights into principles which can be adopted to completely redefine the basic concepts of control, structure, interaction and function of the emerging pervasive environments. The study of the rules of genetics and evolution combined with mobility, leads to the definition of service oriented communication systems which are autonomous, and autonomously self-adaptive. The objective of this article is to ascertain how this paradigm shift, which views a network only as a randomly self-organizing by-product of a collection of self-optimizing services, may become the enabler of the new world of omnipresent low cost pervasive environments of the future.

Waveband switching in light trail optical networks with dynamic traffic [Invited]

Feature Issue on Waveband Switching, Routing, and GroomingWavelength switching is used in current light-path networks to set up connections between node pairs. With the increase in the number of wavelengths per fiber, waveband switching has been proposed for decreasing the number of switching ports in optical nodes. Another concept called a light trail allows the intermediate nodes along a light path to access the wavelength channel, aiming at the reduction of the total number of wavelengths. Both techniques apply traffic grooming on different levels of a WDM network. We combine and compare these two switching techniques: waveband switching light path (WBS-LP) and waveband switching light trail (WBS-LT). For both WBS-LP and WBS-LT networks, auxiliary graph models are proposed to exploit not only the wavelength resources in the fiber links but also the limited waveband port resources inside multigranular optical cross connect (MG-OXC) nodes. The proposed algorithms are compared with shortest path, least-weighted path, and K-least-weighted path algorithms. Numerical simulations show that the proposed algorithms based on the auxiliary graph models (LPlowbarAG-LTlowbarAG) have better performance than other algorithms. For different algorithms, WBS-LT can have better blocking performance than WBS-LP, especially when add-drop waveband ports are critical resources.

Design considerations on the CREATE-NET testbed

The CREATE-NET testbed is a long term project aiming at implementing a best state-of-the-art infrastructure able to link together research centers, both from academia and industrial bodies, in order to create a fruitful collaborative environment to help generating new ideas for advanced applications and services, developing new protocols, testing and integrating different vendor equipments. This testbed is aimed to be unique as it covers novel topics such as optical and wireless integration and WiMAX experimentation for offering broadband access to rural communities. In this paper we present both the technical design issues and a general outline of the implementation process.

From Internets to Bionets: Biological Kinetic Service Oriented Networks

As the trend toward ubiquitous and pervasive computing continues to gain momentum, new networking paradigms need to be developed to keep pace with the needs of this emerging environment. In the near future we can expect the number of nodes to grow by multiple orders of magnitude as tags, sensors, body networks etc., get fully integrated into the communication superstructure. Not only will the amount of information in these all-embracing pervasive environments be enormous and to a large degree localized, but also the relaying needs for maintaining an end to end reliable ‘always on’ networks, as we know today, will be, for the vast majority of the pervasive users beyond their resource capabilities, and in addition redundant, considering the needs of the personalized services dominating these networks. The ambiance within which these nodes will act will be intelligent, mobile, self-cognitive and not limited to machine to machine communication. In these networks the end to end concept of always on communication that formed the basis of the Internet for the last three decades will become passe. The next ‘Internet’ frontier will be the challenge of adjusting to the omnipresent, intelligent and self-cognitive networking environments which are becoming an integral part of the new societal reality.

Traffic Grooming Techniques in Optical Networks

With the increase of the number of wavelengths per fiber, waveband switching has been proposed to decrease the number of switching ports in optical nodes. Another concept, that of Light trails, allows the intermediate nodes along a lightpath to access the wavelength channel, aiming at the reduction of the number of wavelengths. Both techniques apply traffic grooming on different levels of the WDM network. In this paper, we combine them and compare the two switching techniques: waveband switching lightpath (WBS-LP) and waveband switching lighttrail (WBS-LT). Auxiliary graph models (LP_AG/LT_AG) are proposed for WBS-LP/WBS-LT respectively. These two auxiliary graph models can exploit not only the wavelength resource in the fiber links but also the limited waveband ports resource inside the multi-granular optical cross connects (MG-OXC) nodes. The influence of network parameters, e.g. number of wavebands, ports and transceivers, is studied. The proposed algorithms are compared with shortest path (SP), least-weighted path (LW), and K-least-weighted path (KP) algorithms; numerical simulations show their better performance. For different algorithms, WBS-LT can have better blocking performance than WBS-LP especially when add/drop waveband ports are the critical resources.