Marcin Filo

Cognitive control channels: from concept to identification of implementation options

Recent effort related to cognitive radio systems has lead to an in-depth analysis of context information management and exploitation based on a cognitive control channel for enhancement of management needed for, say, suitable link selection in a heterogeneous radio framework, dynamic radio resource management, and distributed sensing. Concerning the actual implementation of such a CCC, the focus was recently moved toward an in-band solution, where the information is transported building on existing radio access technologies. In this scope, this article illustrates relevant technical scenarios in which CCCs can be exploited and outlines a set of derived system requirements. The article provides an overview of various possible RAT independent and dependent implementation options, such as Diameter, distributed agents, 3GPP radio resource control (RRC) mechanisms, IEEE 802.21, IEEE 802.11, WiMedia UWB, and Bluetooth. The advantages and drawbacks of the various options are discussed.

Multi-RAT Dynamic Spectrum Access for 5G Heterogeneous Networks: The SPEED-5G Approach

Research and development of technologies that address the challenges of predicted growth in mobile connections and traffic volume is well known. A major challenge is the cost of meeting the objective, in terms of both infrastructure and deployment. Today, lack of dynamic control across wireless network resources is leading to unbalanced spectrum loads and a perceived capacity bottleneck. The solutions proposed by SPEED-5G through extended dynamic spectrum access (eDSA) address traffic allocation over heterogeneous wireless technologies, better load balancing across available spectrum bands, and capacity boosting through aggregation of available resources while ensuring fair coexistence. The objective of this article is to present a new framework for MAC and RRM layers for supporting eDSA and requirements of the next-generation networks.

The 802.11g relaying MAC that saves energy

In this paper we focus on energy efficient opportunistic relaying in WLANs. We propose and examine an extension to IEEE 802.11g MAC protocol that enables self-enforced relaying, where the main idea behind the relaying is to decrease overall energy expenses in WLANs. Since frame transmission and reception require spending some energy by wireless nodes as well as access points, it is desirable for every node in a wireless system to get access to the channel as fast as possible and occupy it for a reasonably short period. In our proposal the protocol extension uses RTS/CTS mechanisms to precede every transmission and employs intermediate nodes which may serve as relays. Potential relays in the network are self-motivated to perform as helpers since remaining in idle mode or waiting for channel access also requires energy. Therefore, by helping other ongoing transmissions, relays may decrease total transmission time and increase their possibility of being awarded faster access to wireless medium, which eventually yields decrease in energy consumptions. Experimentation results prove that opportunistic relaying provides energy savings in 802.11g-based WLANs.

Performance impact of antenna height in Ultra-Dense cellular Networks

The concept of Ultra Dense Networks (UDNs) is often seen as a key enabler of the next generation mobile networks. However, existing analysis of UDNs, including Stochastic Geometry, has not been able to fully determine the potential gains and limits of densification. In this paper we study performance of UDNs in downlink and provide new insights on the impact of antenna height on the network performance. We focus our investigation on the probability of coverage, average rate and average area rate for random deployments and show that under a path-loss model which considers antenna height there exists an upper limit on network performance which is dependent on the path-loss model parameters. Our analysis shows an interesting finding that even for over-densified networks a non-negligible system performance can be achieved.

Evaluation of the DSC algorithm and the BSS color scheme in dense cellular-like IEEE 802.11ax deployments

Coping with the extreme growth of the number of users is one of the main challenges for the future IEEE 802.11 networks. The high interference level, along with the conventional standardized carrier sensing approaches, will degrade the network performance. To tackle these challenges, the Dynamic Sensitivity Control (DSC) and the BSS Color scheme are considered in IEEE 802.11ax and IEEE 802.11ah, respectively. The main purpose of these schemes is to enhance the network throughput and improve the spectrum efficiency in dense networks. In this paper, we evaluate the DSC and the BSS Color scheme along with the PARTIAL-AID (PAID) feature introduced in IEEE 802.11ac, in terms of throughput and fairness. We also, exploit the performance when the aforementioned techniques are combined. The simulations show a significant gain in total throughput when these techniques are applied.

Toward 5G: Smart and Green Scenarios

The first wave of 4th Generation systems is finally being deployed over Europe, providing a vehicle for broadband mobile services at anytime, anyplace and anywhere. However, mobile traffic is still growing (Cisco in Visual Networking Index: Global Mobile Data Traffic Forecast Update 2012–2017, [1]) and the need for more sophisticated broadband services will further push the limit on current standards to provide even tighter integration between wireless technologies and higher speeds, requiring a new generation of mobile communications: the so-called 5G. The evolution towards 5G is considered to be the convergence of internet services with legacy mobile networking standards leading to the commonly used term “mobile internet” over heterogeneous networks (HetNets), with very high connectivity speeds. In addition, green communications seem to play a pivotal role in this evolutionary path with key mobile stake holders driving momentum towards a greener society through cost-effective design approaches. In fact it is becoming increasingly clear from new emerging services and technological trends that energy and cost per bit reduction, service ubiquity, and high speed connectivity are becoming desirable traits for next generation networks. This chapter provides an introduction to the solutions presented in the book, by investigating potential smart and energy efficient scenarios for the 5G paradigm, which explores how cooperation working in synergy with seamless handovers using context information can provide the platform for significant energy saving at the mobile device. Given these scenarios, we define the system requirements and propose a functional architecture on which solutions proposed throughout this book are built.