Kais Mnif

Virtual backbone based on MCDS for topology control in wireless ad hoc networks

This paper proposes to utilize virtual backbone to handle control messages in ad hoc networks. The virtual backbone is built by using the Minimum Connected Dominating Set (MCDS) on a graph. The first part of this paper presents a new algorithm to construct the MCDS. The construction of the MCDS is formulated using the linear programming approach. We compared the performance of this procedure with those other previous approaches, and we find that our approach is less complex and gives the nearest solution to the optimal one. The second part of this paper presents different techniques of diffusion in ad hoc networks such as flooding, clustering, MP relay, and backbone based on MCDS, etc. The flooding technique is simple and efficient, but it is expensive in term of bandwidth, and causes excessive flows of message etc. Simulation results show that the approach of virtual backbone based MCDS outperforms flooding and MP relay.

Adaptive efficient downlink packet scheduling algorithm in LTE-advanced system

For a better exploitation of radio resources in the fourth generation networks (4G) Long Term Evolution-Advanced (LTE-A) and for a better guarantee of service quality requested for users, radio resources management and specifically scheduling, play a key role in reaching the objective. In this paper, we propose a new packet scheduling (PS) algorithm for LTE-A downlink transmission that adds a new functionality of an adaptive Time Domain (TD) scheduler to adaptively allocate available resources to GBR (Guaranteed Bit Rate) and NGBR (Non GBR) traffic. Evaluation of our algorithm and comparison with previous works are also presented. The simulation results have demonstrated the effectiveness of our algorithm in terms of the system throughput as well as the delay and the Packet Drop Rate (PDR) for both GBR and NGBR traffic.

An overview of quality assessment methods of video transmission over wireless networks

Video streaming presents the professional communicator with a whole new way to deliver information, messages, and entertainment. As third generation wireless networks are deployed, they offer the possibility to view video from mobile terminals. Video transmission is very sensitive to bit errors especially in wireless transmission (packet loss, end to end delay, etc.), the encoder used for transmission affect also the quality of video, thats why it is important to search a method that monitor and adjust the quality of a video sequence. In this paper, a survey of existing quality assessment methods monitor methods is presented. Indeed, three methods will be detailed: objective metrics, subjective evaluation and pseudo-subjective assessment. The discussion includes the advantages and disadvantages of each method.

New scheduling algorithm for Uplink LTE system

In the LTE (Long Term Evolution) System, packet scheduling is considered the most important step of RRM (Radio Resource Management) to have better resource utilization. In this context, we proposed a new Uplink scheduling scheme for LTE networks and compared its performances with other well known algorithms such as the RME (Recursive Maximum Expansion), the RR (Round Robin) and the BCQI (Best-CQI) Uplink schedulers algorithms. The RR scheduler is characterized by a high fairness, but low data rates at cell level. On the other hand, the RME scheduler is characterized by its low complexity, but poor fairness. Also, the BCQI scheme is characterized by high data rates, but poor fairness. The main goal of our proposed scheme was to use the Tabu method for to schedule and optimize the allocation of a PRBs (Physical Resource Blocks) efficiently between different users. Simulation results show that the newly proposed scheduling algorithm allows a fair distribution of available LTE resources while keeping an high systems throughput.

New scheduling algorithm for wireless mesh networks

The last decade has shown a rapid growth in wireless communication technologies. Wireless Mesh Networks (WMNs) appear to be a promising evolution of traditional wireless communications. WMNs are involved to support a variety of services and traffic types. Real time applications like Voice over Internet Protocol (VoIP) require a strict Quality of Services (QoS) such as low end-to-end delay, low drop rate and low blocking rate. In this paper, we provide an overview of existing scheduling algorithms for WMNs and we propose a packet scheduling scheme that take wireless channel condition, type of connection (Handoff and new calls), class of service into account. We show that our algorithm assigns priority to real time traffic, and we evaluate efficiency by means of simulations.

Construction and Maintenance of Backbone for Routing Protocols Enhancement in Mobile Ad Hoc Networks

This paper proposes to use virtual backbone structure to handle control messages and reduce the effect of node mobility in mobile ad hoc networks. This structure is effective in reducing the overhead of disseminating control information and can be useful for routing protocols to enhance their performance. This paper presents a new approach to construct and maintain a virtual backbone for ad hoc mobile networks. The construction of backbone is based on the minimum connected dominating set (MCDS). A distributed procedure is presented to maintain the backbone when the mobility is introduced. Terminals in ad hoc networks are free to move anywhere and anytime. Each terminal which changes position has to execute a maintenance procedure to connect to the backbone. Simulations results show the performance of this procedure when mobility and scalability is considered. To validate our approach, we used simulation to show that using backbone, routing protocols can enhance their performances in high dynamic environment. Three reactive protocols (AODV, DSR and TORA) have been used in this simulation

Cross layer architecture with integrated MIH in heterogeneous wireless networks

Abstract Progress in new radio technologies and raise in users’ demands are motivating the deployment of a wide array of wireless networks, ranging from Wireless Local Area Network (WLAN), to fifth generation (5G). These heterogeneous Radio Access Technologies (RATs) are expected to be integrated together to provide mobile users QoS guarantees. Heterogeneous Wireless Networks (HWNs) provide an opportunity for developers to design efficient framework to satisfy stringent QoS requirement. This integration of different networks results in performance degradation when handovers occur during a mobility event. As a result, the effective mobility management protocols are required to support ubiquitous network access by providing seamless handover. In IEEE 802.21 standard, the framework Media Independent Handover (MIH) is proposed to facilitate handover in heterogeneous networks with measurements and triggers from link layers. This article emphasizes in relationship between the MIH framework and different modules in the MAC layer. In order to guarantee the QoS for different service flows with diverse QoS requirements, we propose to design new cross-layer based designs architecture to provide a combined solution for vertical and horizontal handover based on IEEE 802.21 MIH. We propose new modules in different layers and new primitives to facilitate the communication. Conducted simulations demonstrate the effectiveness of the proposed approaches. We evaluate the proposed architecture using a scheduling algorithm which improves system performance as shown by the results presented of a comparative analysis with the NSA (New Scheduling Algorithm) and EDF (Earliest Deadline First) schemes.

Multimedia quality transmission evaluation over wireless networks: a survey

Abstract In recent years, usage of multimedia applications has increased dramatically, especially after the evolution of 3G and 4G technologies. Moreover, the development of new user devices, such as laptops, Smartphone, etc. increased very steeply and rapidly, to support different types of services and different means of communication satisfying user’s needs. Here, the challenge is how to make those services available to users with a high quality; we speak here about quality of service (QoS) and quality of experience. In this survey, we examine different characteristics of wireless networks to determine the enhancements introduced by each technology. Particularly, we focus on the benefits and limitations of three main technologies which are WiMAX, UMTS and LTE, and the role of each one in increasing QoS satisfaction for multimedia application. A comparison is also done between researches already published in Multimedia quality evaluation over wireless networks topic, taking into account some considerations, such QoS parameters, used simulator, assessed applications, etc. All those help us to extract the strengths and limitations of those researches.

Downlink Packet Scheduling Algorithm Using Tabu Method in LTE Systems

This paper addressed the problem of packet scheduling (PS) on the 3GPP Long Term Evolution (LTE) downlink (DL). The main contribution of this work was to propose a new scheduling and resource allocation scheme that deals with QoS requirements. The objectives of this proposed scheduler are to maximize the system’s sum throughput, to allow a fair distribution of available RBs and to handle GBR and NGBR traffic in LTE downlink systems. The performance of the proposed approach was compared with previous resources allocation and scheduling algorithms such as Best-CQI, RR, and QoE downlink schedulers. Simulation results show that it is possible to achieve a considerable gain in both system’s throughput and fairness.

An efficient call admission control scheme for LTE and LTE-A networks

In this paper, a new call admission control scheme is proposed for Long Term Evolution (LTE) network. The calls are classified into new and handoff calls (HCs and NCs). The call admission control scheme gives the priority of handoff call in admission, without totally neglecting new calls. The proposed scheme guarantees quality of service and prevents network congestion. Simulation results show that our call admission control scheme increases session establishment success and resource utilization.