Igmm Ignas Niemegeers

An Analytical Energy Consumption Model for Packet Transfer over Wireless Links

We provide a detailed analytical model for estimating the total energy consumed to exchange a packet over a wireless link. Our model improves many of the current models by considering details such as consumed energy by processing elements of transceivers, packet retransmission, reliability of links, size of data packets and acknowledgments, and also the data rate of wireless links. To develop the model, we use experimental results based on IEEE 802.15.4 devices to show that consumed energy for receiving erroneous packets is comparable to the consumed energy for receiving error-free packets.

Toward a Seamless Communication Architecture for In-building Networks at the 60 GHz band

This paper addresses the issues of designing an infrastructure to support seamless in-building communication at the 60 GHz band. Recently, the 60 GHz band has received much attention due to its 5 GHz of available spectrum. However, the propagation of signals in this band is strongly hindered by attenuation and line-of-sight requirements. The situation gets worse in the in-building environment where signal propagation is obstructed by physical objects such as walls, furniture etc. In this paper, we present a novel radio over fiber (RoF) architecture that is cost-effective and is able to deliver high data-rate of the order of gigabits. To ensure a seamless communication environment at the 60 GHz band, we propose the concept of extended cells (EC) in order to create sufficient overlap areas. Finally, we illustrate the effectiveness of the proposed architecture by simulating an in-building network at the 60 GHz band employing the RoF and EC concepts

Address autoconfiguration in wireless ad hoc networks: protocols and techniques

With the advent of smaller devices having higher computational capacity and wireless communication capabilities, the world is becoming completely networked. Although, the mobile nature of these devices provides ubiquitous services, it also poses many challenges. In this article, we look in depth at the problem of addressing in wireless ad hoc networks and the currently available techniques and protocols for both IPv4 and IPv6. We present an exhaustive study of the literature and summarize the features of each technique. We believe that this analysis will be helpful for network and application designers, as well as for researchers.

Architectural options for the WLAN integration at the UMTS radio access level

Integration of UMTS and WLAN networks can be done at different levels. A promising interworking approach, expected to support seamless vertical handovers, is the one where the WLAN is embedded in the UMTS radio access network. It is suitable for 3G operators, which are provided with extra license-free bandwidth in hot spots. This paper addresses this type of integration, discussing two types of network architecture. These architectures differ in the UMTS interface at which the WLAN is integrated. The focus is put on the WLAN integration at the Iub interface. Several possible architectural options and necessary modifications are discussed. An Iub-based option, where user data is transferred via the WLAN, while the signalling is exchanged over the WCDMA interface is presented more in detail.

CogCell: cognitive interplay between 60 GHz picocells and 2.4/5 GHz hotspots in the 5G era

The rapid proliferation of wireless communication devices and the emergence of a variety of new applications have triggered investigations into next-generation mobile broadband systems, i.e. 5G. Legacy 2G-4G systems covering large areas were envisioned to serve both indoor and outdoor environments. However, in the 5G era, 80 percent of all traffic is expected to be generated indoors. Hence, the current approach of macrocell mobile networks, where there is no differentiation between indoors and outdoors, needs to be reconsidered. We envision 60 GHz mmWave picocell architecture to support highspeed indoor and hotspot communications. We envisage the 5G indoor network as a combination of, and interplay between, 2.4/5 GHz having robust coverage and 60 GHz links offering a high data rate. This requires intelligent coordination and cooperation. We propose a 60 GHz picocellular network architecture, called CogCell, leveraging ubiquitous WiFi. We propose to use 60 GHz for the data plane and 2.4/5GHz for the control plane. The hybrid network architecture considers an opportunistic fall-back to 2.4/5 GHz in case of poor connectivity in the 60 GHz domain. Further, to avoid the frequent re-beamforming in 60 GHz directional links due to mobility, we propose a cognitive module, a sensor- assisted intelligent beam switching procedure, that reduces communication overhead. We believe that the CogCell concept will help future indoor communications and possibly outdoor hotspots, where mobile stations and access points collaborate with each other to improve the user experience.

Vertical handovers among different wireless technologies in a UMTS radio access-based integrated architecture

The demands for accessing services at high data rates while on the move, anyplace and anytime, resulted in numerous research efforts to integrate heterogeneous wireless and mobile networks. The focus was mainly put on the integration of the Universal Mobile Telecommunications System (UMTS) and the wireless local area network (WLAN) IEEE 802.11, which is beneficial in terms of capacity, coverage and cost. With the advent of IEEE 802.16(e) the attention of the research community was shifted to its interworking, on one side, with complementary WLANs, and on the other, with UMTS for extra capacity. In addition, there has been also research on UMTS interworking with different broadcasting systems, including the Digital Video Broadcasting system for handheld devices (DVB-H). All these research activities resulted in various heterogeneous architectures where the interworking was performed at different levels in the network. In this article, we address the integration at the UMTS radio access level, known also as very tight coupling. This integration approach exhibits good vertical handover performance and may allow for seamless session continuity during the handover. However, it is a technology specific solution, where not all the mechanisms applied to the integration of one wireless technology can be straightforwardly reused for embedding another. This integration approach introduces various modifications to UMTS that have to be standardized, which makes it a long-term solution. We present here the general architecture for the integration at the UMTS radio access level and discuss the extension of the architectural framework for various types of access systems with as few as possible additional modifications. The focus of the work is put on the vertical handovers. We discuss various vertical handovers among WCDMA, IEEE 802.11, IEEE 802.16e and DVB-H in the considered heterogeneous architecture. We present new handover types, describe the vertical handover procedures and provide performance evaluation of the vertical handovers in different scenarios and for different combinations of the wireless access technologies.

An architectural framework for 5G indoor communications

In this paper, we emphasize on indoor networks in 5G era. We explore the possible technologies and architectural solutions for 5G indoor communications. Owing to the fact that requirements for indoor and outdoor communications will be quite different in the next generation networks, we try to define an architectural framework for 5G indoor communications. Our proposed architecture focuses on three aspects of indoor network architecture, namely; air interface, backhaul connectivity and indoor signal distribution.

60 GHz MAC standardization: Progress and way forward

Communication at mmWave frequencies has been the focus in the recent years. In this paper, we discuss standardization efforts in 60 GHz short range communication and the progress therein. We compare the available standards in terms of network architecture, medium access control mechanisms, physical layer techniques and several other features. Comparative analysis indicates that IEEE 802.11ad is likely to lead the short-range indoor communication at 60 GHz. We bring to the fore resolved and unresolved issues pertaining to robust WLAN connectivity at 60 GHz. Further, we discuss the role of mmWave bands in 5G communication scenarios and highlight the further efforts required in terms of research and standardization.

Green hybrid Fi-Wi LAN

Enterprise WLANs encompassing supernumerary Access Points (APs) are being used to provide capacity to indoor environments. The approach of over dimensioned deployment of APs to meet the capacity needs of users at critical time points are advocated without little concern towards the important issue of power wastage. For a sustainable greener environment the issue of power saving in such enterprise WLANs has to be integrated in our present day design. Hybrid Fiber-Wireless (Fi-Wi) LAN is envisioned as the evolution of enterprise WLAN which can help us enormously to reduce the power wastage while meeting the demands of the indoor users. In this paper, we propose a hybrid Fi-Wi LAN architecture based On Demand Strategy which results in massive power saving (approximately 60%) by switching of APs or Cell Access Nodes (CANs) based on user demand estimation while maintaining coverage throughout the whole cell area.

Cell switching mechanisms for access point sharing in WLAN over radio-over-fiber systems

Radio-over-fiber (RoF) technology is a promising candidate to provide high data rates and ubiquitous coverage by distributing small cells over the service area. For wireless LAN (WLAN) application in RoF systems, an access points (AP) can be shared among multiple small cells. The medium access mechanisms in the distributed coordination function (DCF) under this context encounter some issues due to the carrier sensing failure between the nodes in different cells. For alleviating this problem and also supporting flexible AP sharing, two switching mechanisms are discussed. One employs a time division scheme for sharing the APs and the other a selective reception of uplink frames among the associated cells. Both approaches are shown to be effective. The proposed mechanisms do not require changes in the existing protocols on both the client side and AP side. And they are complementary to each other due to their different switching principles.