Integration of TV White Space and Femtocell Networks.

PhDFemtocell is an effective approach to increase system capacity in cellular networks. Since traditional Femtocells use the same frequency band as the cellular network, cross-tier and co-tier interference exist in such Femtocell networks and have a major impact on deteriorating the system throughput. In order to tackle these challenges, interference mitigation has drawn attentions from both academia and industry. TV White Space (TVWS) is a newly opened portion of spectrum, which comes from the spare spectrum created by the transition from analogue TV to digital TV. It can be utilized by using cognitive radio technology according to the policies from telecommunications regulators. This thesis considers using locally available TVWS to reduce the interference in Femtocell networks. The objective of this research is to mitigate the downlink cross-tier and co-tier interference in different Femtocell deployment scenarios, and increase the throughput of the overall system. A Geo-location database model to obtain locally available TVWS information in UK is developed in this research. The database is designed using power control method to calculate available TVWS channels and maximum allowable transmit power based on digital TV transmitter information in UK and regulations on unlicensed use of TVWS. The proposed database model is firstly combined with a grid-based resource allocation scheme and investigated in a simplified Femtocell network to demonstrate the gains of using TVWS in Femtocell networks. Furthermore, two Femtocell deployment scenarios are studied in this research. In the suburban Femtocell deployment scenario, a novel system architecture that consists of the Geo-location database and a resource allocation scheme using TVWS is proposed to mitigate cross-tier interference between Macrocell and Femtocells. In the dense Femtocell deployment scenario, a power efficient resource allocation scheme is proposed to maximize the throughput of Femtocells while limiting the co-tier interference among Femtocells. The optimization problem in the power efficient scheme is solved by using sequential quadratic programming method. The simulation results show that the proposed schemes can effectively mitigate the interference in Femtocell networks in practical deployment scenarios

Integration of a genetic optimisation algorithm in a simulation framework for optimising femtocell networks.

The developments in mobile communication systems from 1G to 4G have increased demands on the network due to the increased number of devices and increasing volume of data and 5G is expected to significantly increase demands further. Therefore, networks need to be more efficient to deliver the expected increase in volume. An energy and cost efficient way to cope with such an anticipated increase in the demand of voice and data is the dense deployment of small cells i.e. femtocells. Femtocells are identified as a crucial way to the delivery of the increased demands for heterogeneous networks in which macrocells work in combination with femtocells to provide coverage to offices, homes and enterprise. A survey of the literature is conducted to examine the mechanisms and approaches different authors have used to optimise the network. One of the major activities in this project before the transfer was the identification of the parameters. The literature was analysed and key performance parameters were identified. Based on the identified key performance parameters, a simulation framework is used to perform the experiments and to analyse the performance of a two-tier LTE-A system having femtocell overlays. A comprehensive and easy to use graphical user interface has been set up with the desired two- tier network topologies. It estimates the throughput and path loss of all the femto and macro users for all the supported bandwidths of an LTE-A system using different modulation schemes. A series of tests are carried out using the described simulation framework for a range of scenarios. The modulation scheme that yield highest throughput for a femtocell user is identified, and path loss is found to be independent from the modulation scheme but is dependent on the distance from its base station. In another series of experiments, the effects that walls inside buildings have on connectivity are examined and positioning of the femtocells is changed for each scenario inside buildings to analyse the performance. These results are used to find the optimised location of femtocells in different room layouts of the building. The simulation framework is further developed to be able to optimise the whole femtocell network by finding the optimised positioning of femtocells using the genetic optimisation algorithm. The end user can provide the inputs of the desired network topology to the simulation framework through a graphical user interface. The throughput and path loss of all the femto users are calculated before and after optimisation. The simulation results are generated in the form of tables before and after optimisation for comparison and analysis. The layouts depicting the indoor environment of the building before and after optimisation can be seen and analysed through the graphical user interface developed as a part of this simulation framework. Two case studies are defined and described to test the capacity and capability of the developed simulation framework and to show how the simulation framework can be used to identify the optimum positions of the femtocells under different configurations of room designs and number of users that represent contrasting loads on the network. Any desired network topology can be created and analysed on the basis of throughput and path loss by using this simulation framework to optimise the femtocell networks in an indoor environment of the building. The results of the experiments are compared against the claims in other published research

Optimization of Mobility Parameters using Fuzzy Logic and Reinforcement Learning in Self-Organizing Networks

In this thesis, several optimization techniques for next-generation wireless networks are proposed to solve different problems in the field of Self-Organizing Networks and heterogeneous networks. The common basis of these problems is that network parameters are automatically tuned to deal with the specific problem. As the set of network parameters is extremely large, this work mainly focuses on parameters involved in mobility management. In addition, the proposed self-tuning schemes are based on Fuzzy Logic Controllers (FLC), whose potential lies in the capability to express the knowledge in a similar way to the human perception and reasoning. In addition, in those cases in which a mathematical approach has been required to optimize the behavior of the FLC, the selected solution has been Reinforcement Learning, since this methodology is especially appropriate for learning from interaction, which becomes essential in complex systems such as wireless networks. Taking this into account, firstly, a new Mobility Load Balancing (MLB) scheme is proposed to solve persistent congestion problems in next-generation wireless networks, in particular, due to an uneven spatial traffic distribution, which typically leads to an inefficient usage of resources. A key feature of the proposed algorithm is that not only the parameters are optimized, but also the parameter tuning strategy. Secondly, a novel MLB algorithm for enterprise femtocells scenarios is proposed. Such scenarios are characterized by the lack of a thorough deployment of these low-cost nodes, meaning that a more efficient use of radio resources can be achieved by applying effective MLB schemes. As in the previous problem, the optimization of the self-tuning process is also studied in this case. Thirdly, a new self-tuning algorithm for Mobility Robustness Optimization (MRO) is proposed. This study includes the impact of context factors such as the system load and user speed, as well as a proposal for coordination between the designed MLB and MRO functions. Fourthly, a novel self-tuning algorithm for Traffic Steering (TS) in heterogeneous networks is proposed. The main features of the proposed algorithm are the flexibility to support different operator policies and the adaptation capability to network variations. Finally, with the aim of validating the proposed techniques, a dynamic system-level simulator for Long-Term Evolution (LTE) networks has been designed

Energy Efficiency

This book is one of the most comprehensive and up-to-date books written on Energy Efficiency. The readers will learn about different technologies for energy efficiency policies and programs to reduce the amount of energy. The book provides some studies and specific sets of policies and programs that are implemented in order to maximize the potential for energy efficiency improvement. It contains unique insights from scientists with academic and industrial expertise in the field of energy efficiency collected in this multi-disciplinary forum

On Improving Data Rates of Users in LTE HetNets

The proliferation of smartphones and tablets has led to huge demand for data services over cellular networks. Cisco VNI mobile forecast (2014-2019) tells that although only 3.9% of mobile connections were Long Term Evolution (LTE) based they accounted for 40% of the mobile traffic and this will rise to 51% by 2019, by which the mobile data usage will grow 11 fold to over 15 Exabytes per month. Reports by Cisco and Huawei tell that 70% of the traffic is generated in indoor environments such as homes, enterprise buildings and hotspots. Hence, it is very important for mobile operators to improve coverage and capacity of indoor environments. Indoor data demand is partly met by intensifying the deployment of Macro Base Stations (MBSs/eNodeBs) in LTE cellular networks. Owing to many obstacles in the communication path between MBS and users inside the building, radio signals attenuate at a faster rate as the distance increases. Thus, Indoor User Equipments (IUEs) receive still low signal strength ( i.e., Signal-to-Noise Ratio, SNR) compared to Outdoor User Equipments (OUEs). To address this problem, one can deploy a large number of Low Power Nodes (LPNs) a.k.a. small cells (e.g., Picos and Femtos) under an umbrella MBS coverage and thereby form an LTE Heterogeneous Network (HetNet). Small cells are mainly being deployed in homes, enterprise buildings and hotspots like shopping malls and airports to improve indoor coverage and data rates. This is a win-win situation as telecom operators also benefit by reduction in their CAPEX and OPEX. Though the deployment of Femtocells improves indoor data rates, the resulting LTE HetNet may face a host of problems like co-tier and cross-tier interference (due to frequency reuse one in LTE) and frequent handovers (due to short coverage areas of Femtocells). Deployment of Femtos inside a building can lead to signal leakage at the edges/corners of the buildings. This causes cross-tier interference and degrades the performance of OUEs in High Interference Zone (HIZone) around the building area, which are connected to one of the MBSs in the LTE HetNet. Arbitrary placement of Femtos can lead to high co-channel cross-tier interference among Femtos and Macro BSs and coverage holes inside buildings. If Femtos are placed without power control, this leads to high power consumption and high inter-cell interference in large scale deployments. Our goal is to address these problems by developing efficient architecture, Femto placement and power control schemes in LTE HetNets. Random or unplanned placement of the Femtos leads to poor SNR and hence affects achievable data rates of IUEs. Hence, placement of Femtos is important for the cellular operators to perform planned deployment of minimum number of Femtos with no coverage holes and guarantee a good signal quality with no co-tier interference. Once the placement of Femtos is done optimally in enterprise environments, operators need to ensure that traffic load is evenly distributed among neighboring Femtos for improving Quality of Service (QoS) of IUEs by efficiently utilizing the network resources. In traditional cellular networks, the uplink access and downlink access of UEs are coupled to the same (Femto) cell. Suppose a Femto is fully loaded when compared to its neighboring Femtos, the traditional offloading or load balancing algorithms will try offloading some of the UEs for both their uplink and downlink access from the loaded cell to one of less loaded neighboring cells (i.e., target cell) provided that these UEs could get connected to the chosen target cell. This type of offloading is a forced handover to reduce traffic imbalance and trigger for handover is not based on better signal strength from the target cell. But, the offloaded UEs are connected for both their uplink and downlink access to the same target cell. Since UEs are most likely separated by walls and floors from their connected cells in enterprise environments, these offloaded UEs now have to transmit with higher transmit power in the uplink and thereby affects their battery lives. In order to reduce the battery drain for the offloaded UEs while maintaining their QoS, we employ the Decoupled Uplink and Downlink (DUD) access method in such a way that, the uplink of UE is connected to the closest Femto while the downlink is connected to a less loaded neighboring Femto. To maximize the utilization of the limited operating spectrum and provide higher data rate for IUEs, operators can configure Femtos in open access mode with frequency reuse one (i.e., all Femtos and MBSs operates on a same frequency) in LTE HetNets. However, this leads to high co-tier interference and cross-tier interference. Another problem in enterprise buildings having Femtos is frequent handovers, that happens when IUEs move from one room/floor to another room/floor inside the building. This leads to degradation of network performance in terms of increased signaling overhead and low throughputs. In order to reduce this kind of unnecessary handovers in enterprise buildings, Femtos should be placed optimally with handover constraints. Hence, we obtain the optimal coordinates from the OptHO model by adding handover constraints to the Minimize Number of Femtos (MinNF) model which guarantees threshold Signal-to-Interference plus Noise Ratio (SINR) of -2 dB for all IUEs inside the building. Such optimized deployment of Femtos reduces the number of handovers while guaranteeing good SINR to all IUEs. In LTE HetNets, even though planned deployment of Femtos in open access mode boosts the IUEs performance, the power leakage from indoor Femtos create interferix ence to the OUEs in the HIZone in the buildings surrounding areas. We propose an efficient placement and power control SON (Self organizing Network) algorithm which optimally places Femtos and dynamically adjusts the transmit power of Femtos based on the occupancy of Macro connected OUEs in the HIZone. To do this, we use the same MinNF model to place the Femtos optimally and solve Optimal Femto Power (OptFP) allocation problem (Mixed Integer Linear Programming (MILP)) which guarantees threshold SINR of -4 dB for IUEs with the Macro users SINR degradation as lesser than 2 dB. In the OptFP model, Femto’s transmit power is tuned dynamically according to the occupancy of OUEs in the HIZone. But the presence of even a single OUE in the HIZone decreases SINR of numerous IUEs, which is not fair to IUEs. In order to address this issue, we propose two solutions a) On improving SINR in LTE HetNets with D2D relays and b) A novel resource allocation and power control mechanism for Hybrid Access Femtos in LTE HetNets, which we describe in the following two paragraphs. To guarantee certain minimum SINR and fairness to both IUEs and OUEs in HIZone, we consider a system model by applying the concept of Device-to-Device (D2D) communication wherein free/idle IUEs connected to Femto act like UE-relays (i.e., UE-like BS, forwarding downlink data plane traffic for some of the HIZone users connected to MBS). We formulate a Mixed-Integer Linear Programming (MILP) optimization model which efficiently establishes D2D pairs between free/idle celledge IUEs and HIZone users by guaranteeing certain SINRT h for both IUEs and HIZone users. As D2D MILP model takes more computation time, it is not usable in real-world scenarios for establishing D2D pairs on the fly. Hence, we propose a two-step D2D heuristic algorithm for establishing D2D pairs. In above works, we assume that Femtos are configured in open access mode. But Hybrid Access Femtocells (HAFs) are favored by the operators because they ensure the paid Subscribed Group (SG) users certain QoS and then try to maximize the system capacity by serving near-by Non Subscribed Group (NSG) users in a best-effort manner. To reap in the benefits of HAFs, the operators need to employ effective resource sharing and scheduling mechanisms to contain co-tier and cross-tier interference arising out of reuse one in the HetNet system. Towards this, we address various challenges in terms of deployment and operation of HAFs in indoor environments. We propose an Optimal Placement of hybrid access Femtos (OPF) model which ensures a certain SINRT h inside the building and a certain SINRT h in the HIZone of the building. Unlike in previous optimization models, in this model, users in HIZone are connected to HAF s deployed inside the building. Also we propose a decentralized Dynamic Bandwidth Allocation (BWA) mechanism which divides the available HAF bandwidth between the two sets of user groups: SG and NSG. In order to mitigate co-tier and cross-tier interference, we then propose a dynamic Optimal Power Control (OPC) mechanism which adjusts the transmit powers of HAFs whenever the users in the HIZone cannot be served by the HAFs. In such a case, HIZone users connect to an MBS instead. Since the OPC problem is hard to solve in polynomial time, we also present a Sub-Optimal Power Control (SOPC) mechanism. To maintain fair resource allocation between SG and NSG users, we propose an Enhanced Priority (EP) scheduling mechanism which employs two schedulers which are based on the Proportional Fair (PF) and the Priority Set (PS) scheduling mechanisms. In above works, placement of Femtos is optimized to reduce co-channel co-tier interference among neighboring Femtos and transmit power of Femtos is optimized to reduce cross-tier interference between MBSs and Femtos. But, for arbitrary deployed Femtos, Inter Cell Interference Coordination (ICIC) techniques could be employed to address co-tier interference problem among Femtos which are connected with each other over X2 interface. Hence, in this work, we propose an ICIC technique, Variable Radius (VR) algorithm which dynamically increases or decreases the cell edge/non-cell edge regions of Femtos and efficiently allocates radio resources among cell edge/non-cell edge regions of Femtos so that the interference between neighboring Femtos can be avoided. We implement the proposed VR algorithm on top of PF scheduler in NS-3 simulator and find that it significantly improves average network throughput when compared to existing techniques in the literature

An Innovative RAN Architecture for Emerging Heterogeneous Networks: The Road to the 5G Era

The global demand for mobile-broadband data services has experienced phenomenal growth over the last few years, driven by the rapid proliferation of smart devices such as smartphones and tablets. This growth is expected to continue unabated as mobile data traffic is predicted to grow anywhere from 20 to 50 times over the next 5 years. Exacerbating the problem is that such unprecedented surge in smartphones usage, which is characterized by frequent short on/off connections and mobility, generates heavy signaling traffic load in the network signaling storms . This consumes a disproportion amount of network resources, compromising network throughput and efficiency, and in extreme cases can cause the Third-Generation (3G) or 4G (long-term evolution (LTE) and LTE-Advanced (LTE-A)) cellular networks to crash. As the conventional approaches of improving the spectral efficiency and/or allocation additional spectrum are fast approaching their theoretical limits, there is a growing consensus that current 3G and 4G (LTE/LTE-A) cellular radio access technologies (RATs) won\u27t be able to meet the anticipated growth in mobile traffic demand. To address these challenges, the wireless industry and standardization bodies have initiated a roadmap for transition from 4G to 5G cellular technology with a key objective to increase capacity by 1000Ã? by 2020 . Even though the technology hasn\u27t been invented yet, the hype around 5G networks has begun to bubble. The emerging consensus is that 5G is not a single technology, but rather a synergistic collection of interworking technical innovations and solutions that collectively address the challenge of traffic growth. The core emerging ingredients that are widely considered the key enabling technologies to realize the envisioned 5G era, listed in the order of importance, are: 1) Heterogeneous networks (HetNets); 2) flexible backhauling; 3) efficient traffic offload techniques; and 4) Self Organizing Networks (SONs). The anticipated solutions delivered by efficient interworking/ integration of these enabling technologies are not simply about throwing more resources and /or spectrum at the challenge. The envisioned solution, however, requires radically different cellular RAN and mobile core architectures that efficiently and cost-effectively deploy and manage radio resources as well as offload mobile traffic from the overloaded core network. The main objective of this thesis is to address the key techno-economics challenges facing the transition from current Fourth-Generation (4G) cellular technology to the 5G era in the context of proposing a novel high-risk revolutionary direction to the design and implementation of the envisioned 5G cellular networks. The ultimate goal is to explore the potential and viability of cost-effectively implementing the 1000x capacity challenge while continuing to provide adequate mobile broadband experience to users. Specifically, this work proposes and devises a novel PON-based HetNet mobile backhaul RAN architecture that: 1) holistically addresses the key techno-economics hurdles facing the implementation of the envisioned 5G cellular technology, specifically, the backhauling and signaling challenges; and 2) enables, for the first time to the best of our knowledge, the support of efficient ground-breaking mobile data and signaling offload techniques, which significantly enhance the performance of both the HetNet-based RAN and LTE-A\u27s core network (Evolved Packet Core (EPC) per 3GPP standard), ensure that core network equipment is used more productively, and moderate the evolving 5G\u27s signaling growth and optimize its impact. To address the backhauling challenge, we propose a cost-effective fiber-based small cell backhaul infrastructure, which leverages existing fibered and powered facilities associated with a PON-based fiber-to-the-Node/Home (FTTN/FTTH)) residential access network. Due to the sharing of existing valuable fiber assets, the proposed PON-based backhaul architecture, in which the small cells are collocated with existing FTTN remote terminals (optical network units (ONUs)), is much more economical than conventional point-to-point (PTP) fiber backhaul designs. A fully distributed ring-based EPON architecture is utilized here as the fiber-based HetNet backhaul. The techno-economics merits of utilizing the proposed PON-based FTTx access HetNet RAN architecture versus that of traditional 4G LTE-A\u27s RAN will be thoroughly examined and quantified. Specifically, we quantify the techno-economics merits of the proposed PON-based HetNet backhaul by comparing its performance versus that of a conventional fiber-based PTP backhaul architecture as a benchmark. It is shown that the purposely selected ring-based PON architecture along with the supporting distributed control plane enable the proposed PON-based FTTx RAN architecture to support several key salient networking features that collectively significantly enhance the overall performance of both the HetNet-based RAN and 4G LTE-A\u27s core (EPC) compared to that of the typical fiber-based PTP backhaul architecture in terms of handoff capability, signaling overhead, overall network throughput and latency, and QoS support. It will also been shown that the proposed HetNet-based RAN architecture is not only capable of providing the typical macro-cell offloading gain (RAN gain) but also can provide ground-breaking EPC offloading gain. The simulation results indicate that the overall capacity of the proposed HetNet scales with the number of deployed small cells, thanks to LTE-A\u27s advanced interference management techniques. For example, if there are 10 deployed outdoor small cells for every macrocell in the network, then the overall capacity will be approximately 10-11x capacity gain over a macro-only network. To reach the 1000x capacity goal, numerous small cells including 3G, 4G, and WiFi (femtos, picos, metros, relays, remote radio heads, distributed antenna systems) need to be deployed indoors and outdoors, at all possible venues (residences and enterprises)

Radio resource scheduling in homogeneous coordinated multi-point joint transmission of future mobile networks

A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD)The demand of mobile users with high data-rate services continues to increase. To satisfy the needs of such mobile users, operators must continue to enhance their existing networks. The radio interface is a well-known bottleneck because the radio spectrum is limited and therefore expensive. Efficient use of the radio spectrum is, therefore, very important. To utilise the spectrum efficiently, any of the channels can be used simultaneously in any of the cells as long as interference generated by the base stations using the same channels is below an acceptable level. In cellular networks based on Orthogonal Frequency Division Multiple Access (OFDMA), inter-cell interference reduces the performance of the link throughput to users close to the cell edge. To improve the performance of cell-edge users, a technique called Coordinated Multi-Point (CoMP) transmission is being researched for use in the next generation of cellular networks. For a network to benefit from CoMP, its utilisation of resources should be scheduled efficiently. The thesis focuses on the resource scheduling algorithm development for CoMP joint transmission scheme in OFDMA-based cellular networks. In addition to the algorithm, the thesis provides an analytical framework for the performance evaluation of the CoMP technique. From the system level simulation results, it has been shown that the proposed resource scheduling based on a joint maximum throughput provides higher spectral efficiency compared with a joint proportional fairness scheduling algorithm under different traffic loads in the network and under different criteria of making cell-edge decision. A hybrid model combining the analytical and simulation approaches has been developed to evaluate the average system throughput. It has been found that the results of the hybrid model are in line with the simulation based results. The benefit of the model is that the throughput of any possible call state in the system can be evaluated. Two empirical path loss models in an indoor-to-outdoor environment of a residential area have been developed based on the measurement data at carrier frequencies 900 MHz and 2 GHz. The models can be used as analytical expressions to estimate the level of interference by a femtocell to a macrocell user in link-level simulations

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Drone Base Station Trajectory Management for Optimal Scheduling in LTE-Based Sparse Delay-Sensitive M2M Networks

Providing connectivity in areas out of reach of the cellular infrastructure is a very active area of research. This connectivity is particularly needed in case of the deployment of machine type communication devices (MTCDs) for critical purposes such as homeland security. In such applications, MTCDs are deployed in areas that are hard to reach using regular communications infrastructure while the collected data is timely critical. Drone-supported communications constitute a new trend in complementing the reach of the terrestrial communication infrastructure. In this study, drones are used as base stations to provide real-time communication services to gather critical data out of a group of MTCDs that are sparsely deployed in a marine environment. Studying different communication technologies as LTE, WiFi, LPWAN and Free-Space Optical communication (FSOC) incorporated with the drone communications was important in the first phase of this research to identify the best candidate for addressing this need. We have determined the cellular technology, and particularly LTE, to be the most suitable candidate to support such applications. In this case, an LTE base station would be mounted on the drone which will help communicate with the different MTCDs to transmit their data to the network backhaul. We then formulate the problem model mathematically and devise the trajectory planning and scheduling algorithm that decides the drone path and the resulting scheduling. Based on this formulation, we decided to compare between an Ant Colony Optimization (ACO) based technique that optimizes the drone movement among the sparsely-deployed MTCDs and a Genetic Algorithm (GA) based solution that achieves the same purpose. This optimization is based on minimizing the energy cost of the drone movement while ensuring the data transmission deadline missing is minimized. We present the results of several simulation experiments that validate the different performance aspects of the technique