Abstract The main goal behind radio resource management (RRM), in any conventional wireless networks, is to efficiently utilize the available resources. Critical and safety communications have very stringent quality of service requirements on reliability and availability. Consequently, the efficient use of resources becomes more compelling when it deals with this type of application. In this context, cellular vehicle‐to‐everything (C‐V2X) communications, enabled by cellular device‐to‐device (D2D), have recently drawn much attention. This is due to their applicability to road safety and traffic efficiency applications, which require information exchange among road users and road‐side entities. This emerging technology, referred hereinafter as LTE‐V or C‐V2X, supports two different communication modes: 3 and 4. Both of the two modes enable direct vehicle‐to‐vehicle (V2V) communications via PC5 interface. However, they differ on how the radio resources are allocated. Several approaches and algorithms are proposed in the literature to address the resource allocation issue. In this paper, a state of the art of the radio resource allocation strategies was made for LTE‐V technology and a qualitative description was carried out of these different schemes. We proposed a classification of these strategies into different categories. This classification identified the different strengths and weaknesses of each proposal. Up to our knowledge, several surveys concerning resource allocation are published in the context of LTE but very few of them focuses on both RRM and vehicular networks.

Visible light communication (VLC) is advocated as a promising technology designed for ubiquitous broadband connectivity. This paper focuses on evaluating the performance of VLC-based on vehicle-to-vehicle communication in a vehicle platoon. We perform mathematical modeling validated by the simulation to determine the probability of failure, usable throughput, virtual service time and activity period of interfering vehicles. The performance results show a very detailed study on the performance of VLC in the presence of disturbing vehicles. VLC technology is considered an effective technique for platoons, which are affected by interfering vehicles.

Vehicle platooning systems improve road active safety while relying on connected vehicles and exchanging critical safety messages. This paper investigates the applicability of visible light communications (VLC) technology among platoon members. An exact mathematical modelling of a VLC platoon system, perturbed by neighbouring vehicles, is conducted to derive computations of quality of service (QoS) parameters. Based on our analytical model, we retrieve the threshold of VLC performance degradation that triggers switching to a radio frequency technology. Selecting suitable RF technology is done using a sigmoid utility function. Performance results show that the implemented vertical handover enables to reduce packet loss and improve QoS parameters.

Enabling direct Vehicle-to-Vehicle (V2V) communications within LTE-V technology is considered as a key technological breakthrough to further deploy vehicle-to-Everything (V2X) applications. As the main goal of these latter is to improve the traffic safety and save lives, any design of a resource allocation scheme under LTE-V has to take into account the stringent requirements of these applications in terms of reliability and latency. In this context, this paper proposes a novel Priority and guarantEed-bAsed Resource aLlocation approach (PEARL) for cellular V2V communications under a mode 3 configuration. Extensive simulations and comparison to other approaches corroborate the out-performance of our proposal to deliver emergency packets with lower delays and higher packet reception rate without impacting the transmission of non-safety V2X packets.

Due to the high mobility and dynamic topology changes of vehicular Ad-hoc Networks (VANETs) which generate scattered networks, the network's performance has become a critical issue for connected and autonomous vehicles deployment. In order to address this issue, the Heterogeneous Vehicular Networks (HVN) paradigm was designed and it consists in a hybridation of the vehicular network (IEEE 802.11p) and the cellular networks (3G/LTE/4G). This makes the vertical handover to be one of the key technologies for the Internet of Vehicles (IoV) deployment. In this paper, we proposed a vertical handover mechanism (PMIP-MIVH) which uses a logical interface and a Distributed PMIPv6 scheme in order to improve the handover performance. Numerical analysis shows that PMIP-MIVH performs well in terms of handover connection times, handover latency and session continuity, specifically in HVN.

Shuttle buses are deployed on roads for public transportation. In order to track their location and guarantee high levels of safety, these vehicles communicate with a monitoring center through a vehicular network. This messages exchange requires a low latency communication, with no interruption and with a reduced packets loss. In this case, the mobility management should be studied carefully. This paper proposes a handover scheme (FSH) based on Software Defined Networking (SDN) technology. FSH provides a soft handover by adopting mobility anticipation and using both vehicle interfaces simultaneously. Moreover, FSH achieves control signaling overhead reduction and network congestion alleviation. The performance evaluation shows that our proposed algorithm reduces handover losses and end to end communication delays.

Vehicle-to-Everything (V2X) communications refer to information exchange between vehicles and various elements of the Intelligent Transportation System (ITS). This communication enables a variety of V2X use cases with different Quality of Service (QoS) requirements. The messages exchange is achieved through a vehicular network that allows the coexistence of various radio access technologies. In this heterogeneous environment, the choice of the technology to deploy is a primordial issue in order to guarantee the QoS needs of V2X applications.This paper provides a network selection framework for V2X use cases based on Software Defined Networking (SDN) technology. The proposed solution is implemented as a SDN application running on top of the SDN controller. Network selection relies on a specific sigmoid utility function and game theory aiming at fulfilling user satisfaction and achieving load balancing.Simulation results show that our framework provides several improvements in terms of QoS guarantee and network load alleviation.

The communication between vehicles and various elements of the Intelligent Transportation System (ITS) is referred by Vehicle-to-Everything (V2X) communications. V2X applications requirements raise outstanding challenges for 5G systems. Network slicing is a prominent solution to support 5G V2X challenges, by providing the ability to create isolated virtual networks over which different traffic flows can travel isolated from each others. One of the most challenging issues in V2X network slicing environment is the mobility management. To this end, this paper provides a mobility management algorithm based on a V2X slicing architecture by implementing a network slice selection function. The effectiveness of our proposal is validated via simulation experiments.

Channel capacity and software definition of radio functions are important issues for Vehicular Ad-hoc NETworks (VANETs). In our paper, we propose to integrate a 5G radio access technology to software defined PHY layer of IEEE 802.11p for frequency reuse. We superpose two signals with Non-orthogonal Multiple Access (NOMA), and we extract them through Successive Interference Cancellation (SIC). NOMA and SIC solutions have been designed using Software Defined Radio (SDR) chains offering PHY reconfigurability. We prove that this solution allows us to superpose two users sharing the same subcarrier frequency at the same time. Simulations have been performed with two quadrature modulators sharing the same subcarrier frequency. NOMA/SIC would improve the network throughput, since after cancellation, the obtained Bit Error Rate (BER) has been reduced.

The target of this paper is to propose a practical low-complexity power allocation algorithm that strikes a good balance between Spectral Efficiency (SE) and power saving for the downlink of interference-limited cellular networks. Because abundant interference usually results from dense frequency reuse and high power transmission, power optimization schemes are critical to interference management in wireless systems. Powerful power optimization schemes can be efficiently implemented in the framework of Self-Organizing Network (SON). In this context, we resort to non-cooperative game theory to devise two distributed power allocation schemes. By only considering SE, our first Power Control Game (PCG) algorithm, deemed SE-PCG, provides high SE but push autonomous eNBs into consuming all available power. To address this shortcoming and enhance Energy Efficiency (EE), we put forward another PCG algorithm, deemed EE-PCG, which inflicts a penalty on power consumption. The originality of our scheme lies in deriving the power penalty through a signaling-free heuristic. We have analyzed the proposed algorithms through extensive numerical simulations and compared them with the state-of-the-art approaches. The results have shown that our algorithms outperform the latter.

The focus of this paper is targeted towards multi-cell 5G networks composed of High Power Node (HPNs) and of simplified Low Power Node (LPNs) co-existing in the same operating area and sharing the scare radio resources. Consequently, high emphasis is given to Inter-Cell Interference Coordination (ICIC) based on multi-resource management techniques that take into account user association to cells. Beside user association, this paper takes also power control and scheduling into consideration. This complex problem is remained largely unsolved, mainly due to its non- convex nature, which makes the global optimal solution difficult to obtain. We address the user association challenge according to the two broadly adopted approaches in wireless networks: the network-centric approach where user association is allocated efficiently in a centralized fashion; and the user-centric approach where distributed allocation is used for reduced complexity. The scheduling and ICIC power control are solved in a centralized fashion, in order to reach an optimal solution of the joint optimization problem.

Although IEEE 802.11p technology is standardized for road safety and efficiency applications, the channel congestion problem is its key weakness necessitating distributed congestion control (DCC) algorithms on different layers of the communication stack. In this paper, we propose DCC-enabled Contention based Forwarding scheme targeting multi-hop dissemination of Decentralised Event Notification Messages (DENMs). The proposed scheme adapts the parameters of the ETSI standardised forwarding scheme, contention based forwarding (CBF), by taking account the channel load condition. Simulation evaluations are carried out to investigate the performances of the proposed scheme targeting a highway scenario and considering that the wireless channel is shared by DENMs and Cooperative Awareness Messages (CAMs), which are periodically broadcasted by individual vehicles. In the simulations, a dual DCC, the facilities layer DCC, which controls CAM generation rates, and the networking layer DCC, CBF2C, which targets DENMs, are applied and evaluated. Simulation results clearly show that DCC on CAM has a significant impact on communication performances of both the DENM and CAM messages. DCC on networking layer further improves performances in terms of packet delivery ratio (PDR), delay, and communication overhead.

Long Term Evolution (LTE) networks are expected to provide enhanced quality of service (QoS) guaranteed services and a high capacity. In this paper, we propose a novel QoS guaranteed cross-layer scheduling algorithm for LTE system. In fact the LTE scheduler is responsible for efficiently allocating the radio resources among mobile users who have different QoS demands. We focus on the resource blocks allocation and the Medium Access Control (MAC) scheduling algorithm. Our study highlights the impact of the Radio Resource Control (RRC) configuration on the overall performance and the Transport Block (TB) filling during the allocation process. Performance results show that the proposed algorithm is effective in enhancing service fairness, throughput and resource optimization. Our proposal aims to find an agreement between fairness, resource availability, the requested rate and service QoS requirements.

Vehicular ad hoc networks (VANETs) promise to increase road safety, enhance road transportation efficiency and offer new communication-based services to road users. However, VANETs based on the European and American standards suffer from limited scalability due to poor robustness to radio channel congestion. At present, most works on congestion mitigation are based on transmit power control, while alternative approaches such as transmit data rate control are less popular. In this paper, transmit power control and transmit data rate control are compared, showing that the latter outperforms the former in a number of test scenarios, and particularly when channel congestion concerns a localized cluster of vehicles. The analysis is focused on the tradeoff between channel congestion mitigation and vehicles broadcast performance. Moreover, this work considers the decisive influence of congestion spatial distribution on the effectiveness of the compared approaches.

EDCA virtual collision management is a penalizing process that occurs in Intelligent Transportation Systems (ITS). It induces unfairness, priority inversion and quality of service degradation. This paper tackles the performance evaluation of the virtual collision management proposed by IEEE in vehicular environment and overviews the quality of service in presence of three ITS applications: Warning to a foggy zone, inter-distance measurement and road awareness. We perform a mathematical modelling based on a discrete Markov chain that tackles vehicles mobility. The objective of our study is to show the impact of virtual collision on vehicular network performance and dimension the RSU coverage area.

The focus of this paper is targeted towards multi-cell dense LTE and LTE-Advanced networks, which are composed of multiple evolved Node B (eNodeB) co-existing in the same operating area and sharing the available radio resources. In such scenarios, momentous emphasis is given towards the techniques that take Inter-Cell Interference (ICI) into account while allocating the scarce radio resources. In this context, we propose solutions for the problem of joint power control and scheduling in the framework of Inter-Cell Interference Coordination (ICIC) in the downlink of LTE OFDMA-based multi-cell systems. Two approaches are adopted to allocate system resources in order to achieve high performance: a centralized approach based on convex optimization and a semi-distributed approach based on non-cooperative game theory. The centralized approach needs a central controller to optimally allocate resources like in LTE CoMP (Coordinated Multipoint). In the semi-distributed approach, eNodeBs coordinate among each other for efficient resource allocation based on local knowledge conveyed by the X2 interface. It turns out that despite the lower complexity of the semi-distributed approach and its inherent adaptability, there is only a slight discrepancy of results among both approaches, which makes the distributed approach much more promising, in particular as a procedure of SON (Self Organized Network).

In order to achieve high data rates in future wireless packet switched cellular networks, aggressive frequency reuse is inevitable due to the scarcity of the radio resources. While intra-cell interference is mostly mitigated and can be ignored, inter-cell interference can severely degrade performances with bad channel quality. Hence, Inter-Cell Interference Coordination (ICIC) is commonly identified as a key radio resource management mechanism to enhance system performance of 4G networks. This paper addresses the problem of ICIC in the downlink of Long Term Evolution (LTE) systems where the resource selection process is apprehended as a potential game. Proving the existence of Nash Equilibriums (NE) shows that stable resource allocations can be reached by selfish Base Stations (BS). We put forward a fully decentralized algorithm based on replicator dynamics to attain the pure NEs of the modeled game. Each BS will endeavor to select a set of favorable resources with low interference based on local knowledge only making use of signaling messages already present in the downlink of LTE systems.

Inter-Cell Interference Coordination (ICIC) is commonly identified as a key radio resource management mechanism to enhance system performance of 4G networks. This paper addresses the problem of ICIC in the downlink of cellular OFDMA systems where the power level selection process of resource blocks (RB) is apprehended as a sub-modular game. The existence of Nash equilibriums (NE) for that type of games shows that stable power allocations can be reached by selfish Base Stations (BS). We put forward a semi distributed algorithm based on best response dynamics to attain the NEs of the modeled game. Based on local knowledge conveyed by the X2 interface in LTE (Long Term Evolution) networks [1], each BS will first select a pool of favorable RBs with low interference. Second, each BS will strive to fix the power level adequately on those selected RBs realizing performances comparable with the Max Power policy that uses full power on selected RBs while achieving substantial power economy. Finally, we compare the obtained results to an optimal global solution to quantify the efficiency loss of the distributed game approach. It turns out that even though the distributed game results are sub-optimal, the low degree of system complexity and the inherent adaptability make the decentralized approach promising especially for dynamic scenarios.

Long Term Evolution (LTE) is the most recent evolution of mobile phone standards; it has been proposed to provide higher throughput and better spectral efficiency. However with the increasing of services applications supported by each device in LTE networks, the resources sharing function is one of the key challenging issues. In this context, Logical Channel Prioritization (LCP) is referred. In this paper, we propose a mathematical model and performance evaluation of the Medium Access Control (MAC) layer scheduling algorithm while considering the source traffic characteristics, thus an original applications mapping. Our study highlights the impact of the Radio Resource Control (RRC) configuration on the overall performance during the Transport Block (TB) construction. Our analysis is based on a numerical study of a discrete time Markov chains and validated by an extensive simulation runs.

Inter-Cell Interference Coordination (ICIC) is commonly identified as a key radio resource management mechanism to enhance system performance of 4G networks. This paper addresses the problem of ICIC in the downlink of cellular OFDMA systems where the resource selection process is apprehended as a congestion game. Proving the existence of Pure Nash equilibriums (PNE) shows that stable resource allocations can be reached by selfish Base Stations (BS). We resort to a fully decentralized algorithm proposed by Berenbrinck et al [1] to attain the PNEs of the modeled game. Each BS will strive to select a pool of favorable resources with low interference based on local knowledge only.

Nowadays, with the abundance of IEEE 802.11 access points (APs), a mobile user has the flexibility to choose one of several APs, each using a separate channel. Rather than relying on the simplistic standardized algorithm to select the AP, it would be preferable to use optimal algorithms that reduce the user data transfer time. In this paper, the AP selection process is apprehended as an ordinal potential game, which is a class of non-cooperative games known to possess at least one pure Nash Equilibrium (PNE). We put forward a fully decentralized algorithm based on replicator dynamics to attain those PNE. Further, to assess the loss in efficiency of the proposed selfish distributed algorithm, we compare its performances against a centralized optimal approach derived by solving a mixed integer linear program.

With the abundance of diverse air interfaces in the same operating area, a mobile user is able to connect concurrently to different wireless access networks in order to meet more easily its target performance. In this paper, we consider the downlink of a multi-class hybrid network with two Radio Access Technologies (RAT): WiMAX and WiFi. We devise a distributed Radio Resource Management (RRM) scheme for elastic traffic that coexists with streaming traffic. The proposed scheduling policy is original in the sense that elastic users have a counterintuitive behaviour: they will try to occupy the least amount possible of bandwidth owing to their delay tolerance to accommodate QoS stringent streaming users. A non-cooperative submodular game is used to load balance the traffic of elastic users between the two available RATs aiming at minimizing their bandwidth consumption. We characterize the Nash Equilibriums (NE) of the resource management game and study the efficiency of a distributed algorithm based on best response dynamics to achieve those equilibriums. The game is played upon every new arrival and an admission control scheme is used to limit the number of ongoing connections so that admitted elastic flows are sustained with a guaranteed minimal rate.

Owing to the proliferation of different Radio Access Technologies (RAT) in the same operating area, a mobile user is capable of connecting concomitantly to diverse wireless networks in order to meet more easily its target performance. In this paper, we consider the downlink of a multi-class hybrid network with two RATs: WiMAX and 3G LTE. We put forward a semi-distributed Radio Resource Management (RRM) scheme for elastic traffic where both the system and mobile users intervene in the resource management policy. The proposed scheduling scheme is original in the sense that users with elastic traffic have a counterintuitive behavior: they will try to occupy the least amount possible of bandwidth to accommodate QoS stringent streaming traffic. A non-cooperative game is used to load balance the traffic of elastic users between the two available RATs aiming at minimizing their bandwidth consumption. We characterize the Nash Equilibriums (NE) of the RRM game and study the efficiency of a best response algorithm to achieve those equilibriums. Moreover, we propose a fully decentralized algorithm based on replicator dynamics to attain NEs. The system role is to apply an admission control algorithm that limits the number of ongoing connections so that elastic traffic is sustained with a guaranteed minimal rate.

Nowadays, with the abundance of diverse air interfaces in the same operating area, advanced Radio Resource Management (RRM) is vital to take advantage of the available system resources. In such a scenario, a mobile user will be able to connect concurrently to different wireless access networks. In this paper, we consider the downlink of a hybrid network with two broadband Radio Access Technologies (RAT): WiMAX and WiFi. Two approaches are proposed to load balance the traffic of every user between the two available RATs: an individual approach where mobile users selfishly strive to improve their performance and a global approach where resource allocation is made in a way to satisfy all mobile users. We devise for the individual approach a fully distributed resource management scheme portrayed as a non-cooperative game. We characterize the Nash equilibriums of the proposed RRM game and put forward a decentralized algorithm based on replicator dynamics to achieve those equilibriums. In the global approach, resources are assigned by the system in order to enhance global performances. For the two approaches, we show that after convergence, each user is connected to a single RAT which avoids costly traffic splitting between available RATs.

Nowadays networks are characterized by the abundance of diverse Radio Access Interfaces (RAI) in the same operating area. The various wireless interfaces can belong to the same Radio Access Technology or not. In such a scenario, a mobile user will be able to select selfishly one of the available radio interfaces in order to enhance its own performance. Therefore, the radio access selection policy is vital and must be designed astutely to avoid resource wastage. In this paper, the RAI selection process is apprehended as a congestion game which is a class of noncooperative games in which users share a common set of limited resources. The cost sustained by a given user depends upon the congestion impact inflected by other users sharing the same resource. Devising distributed resource sharing schemes that optimize user air interface selection depends crucially on the existence of Nash equilibria for the modelling congestion games. In this paper, we model the downlink access for three main broadband technologies (WiMAX, WiFi and 3.5G HSDPA) and study the existence of pure Nash equilibria for various multi-RAI scenarios involving those technologies.

With the ever-increasing proliferation of air interfaces that coexist in the same operating area, advanced Radio Resource Management is crucial to take advantage of the available system resources. In this paper, we consider a downlink multi-class heterogeneous network where cells include two co-localized Radio Access Technologies (RAT): WiMAX [1] and UMTS [2]. We propose a Centralised Access Control algorithm responsible of assigning every arriving user to one of the two RATs, while taking into account the joint spatial distribution of already accepted users, the current load of each RAT, the location of the newly accepted user and its influence on global performance. The routing decision is formulated as a Semi Markov Decision Process (SMDP). We show how to obtain an optimal policy that maximizes a predefined reward function accounting for both the operator and users satisfaction.

Admission control plays an important role in providing the desired Quality of Service (QoS) in wireless networks. It depends on precise estimates of bandwidth available in the network and the bandwidth required by new flows. Estimating these parameters in wireless networks is challenging due to the shared and open nature of the wireless channel. Resources sharing in wireless links imposes a number of problems in a QoS enabled networks. One of the problems is the estimation of the performance of implied radio links. In this article, we present a novel admission control for infrastrure-less clustered wireless networks. The proposed admission control is based on QoS constraints and the lifetime duration of mobile nodes, including speed, power consumption and capacity parameters. Some new schemes are introduced, QoS parameters are negotiated during the admission procedure, and a forced handover technique is developed instead of reject flows using a centralized view of topology. We also propose algorithms that implement these approaches. The simulation results confirm the effectiveness of the admission control schemes.

One of the major challenges for real-time applications over next-generation heterogeneous access networks is the vertical handoff. Such applications require fast and efficient handover that realize service continuity and seamless mobility preserving the security and the QoS. In this paper we propose a new seamless vertical handover solution performing fast authentication while guaranteeing the QoS and the security of real-time communications. The numerical results show better performance of the proposed solution comparing to the conventional schemes in term of signaling cost and packet loss while achieving high security and QoS.

The increasing popularity of mobile wireless networks and various numbers of wireless networks becomes an important challenge. The future generation of wireless networks is expected to integrate a potentially large number of heterogeneous wireless technologies in what could considered a huge step toward universal seamless access. The topology management became here one of the main challenges. Efficient topology control enhances quality of service and provide less congested cell. In this paper we propose a model to control the topology of a infrastructure-less heterogeneous wireless networks (Ad Hoc and WiMAX relay networks), this approach is based on periodic measurements and forced vertical handover techniques with a control layout. Moreover, this proposed model uses a dedicated architecture with different planes (access, communication and control). We have proposed an analytical model and simulation has been used in order to provide performances rewards.

In this paper we propose a hybrid radio access network architecture that aims to connect remote areas to broadband networks. The proposed architecture consists in a WiMAX network for final users which hence can be connected to the internet backbone. In the other hand the WiMAX base stations are connected via the satellite to the wired network to circumvent mobility and long distance issues. To allow routing optimisation and mobility support, mobility management protocols were applied in a hierarchical architecture with a macro and micro handover functions. Performance analysis is given to study the interest of such radio access network.

The convergence of wireless networks is a key solution to deal with the ever-increasing need for bandwidth. In this compound radio environment, users can use concurrently diverse services through multiple RATs. In this paper, we consider a heterogeneous network where cells include two co-localized radio access technologies (RAT): WiMAX and UMTS. The predominance of these systems in nowadays mobile networks underlines the relevance of our choice. We consider the downlink channel for both RATs and two service classes: streaming and elastic traffic. We propose a joint radio resource management (JRRM) algorithm responsible of routing every arriving user to one of the two RATs, while taking into account the load of each RAT, the spatial distribution of already accepted users, the location of the newly admitted user, and its influence on global performance. In a study based on the semi Markov decision process (SMDP) theory, we show how to obtain an optimal policy that maximizes a predefined reward function accounting for both the operator and user satisfaction. In fact, the reward function consists of a financial gain component, an aggregate throughput component and a blocking cost.

With popularity and pervasiveness increase of mobile wireless networks, combining various numbers of wireless networks becomes an important challenge. The fourth generation of wireless communications is expected to integrate a potentially large number of heterogeneous wireless technologies in what could be considered a huge step toward universal seamless access. One of the main challenges for these networks is to control the topology. Efficient topology control enhances quality of service and provides less congested cells. This paper proposes an approach to topology control for the fourth generation networks. This approach is based on periodic measurements and forced handover techniques with a control layout. A seamless protocol for forced handover techniques is also presented. Performance testing highlights the interest of such techniques.

With the growing deployments of UMTS/HSDPA and recently WiMAX, the integration of these two broadband radio networks becomes an important challenge. However, the convergence of UTRAN and IEEE 802.16 as a radio access network is still limited. In this paper we propose a simple adaptation in WiMAX to enhance voice over IP support for end to end telephonic applications between UMTS and WiMAX. Our goal is to allow an operator to propose UMTS service via an 802.16 radio access network or UTRAN as well. First, we super-framed the 802.16 frame to enhance AMR codec compatibility. In addition, we use ON/OFF periods detection of voice sources to decrease the bandwidth allocated for the same number of calls. We then take advantage from the WiMAX uplink frame structure and from the loss tolerance of voice. Performance evaluation (analytical and simulation) is given to illustrate the benefits of our proposal.

In this paper, we propose an analytical model for dimensioning a hierarchical WiMax-WiFi network. Our model consists in replacing a finite number of nodes by an equivalent continuum. The key feature of the proposed model is that it accounts for the effect of interference and for the physical layer and channel characteristics in an easy and straightforward way. On the one hand, our model takes into consideration frequency planning and scheduling aspects; and on the other hand, it provides tractable formulae of the end user mean capacity and coverage probability to dimension properly the network.

Statistical multiple access gives opportunity to decrease bandwidth wastes in radio cellular networks when sources activities are variable. Usually, 2 states exponential on-off models are used for voice sources and to study statistical multiplexing in telephony. In this paper, we propose a distributed algorithm based on a 3-states model with downlink activity detection for a refined prediction. The proposed algorithm makes the distinction between silent sources according to their downlink activities to enhance the statistical multiple access for telephony. Then, silent sources are pre-allocated available channels on the uplink according to their respective switching probabilities; hence the designation "pseudo-deterministic" for our proposed statistical multiple access scheme. Performance evaluation (analytical and simulation model) is given to illustrate the benefits of our proposal.

In wireless systems, the radio resources are precious, and available bandwidth is shared between users in a given radio cell. Our objective is to define a resource allocation schemes, to permit an efficient sharing of uplink bandwith between different supported traffic categories. So call admission control procedure can be defined. In this work analytical Markov model was proposed, in order to define a resources allocation scheme for voice and data traffic integration in heterogeneous satellite- UMTS network (S-UMTS).

This paper aims to design a self-configuring cellular radio access network. It is a WiMAX based meshed network where base stations form a Cellular IP, all radio network. We then take advantage of mesh networks fast-deployment and self-organising properties, and of cellular networks high mobility support. In the proposed model, WiMAX nodes, or SSs, form the wireless mesh network and in the other hand connect mobile terminals in an infrastructure mode via another radio interface so acting as base stations. The main goal is to obtain a multi-hop, self-organised cellular wireless network that allows users to connect in a centralised mode and operator to deploy easily and quickly a radio access network. Performance analysis is given to study the interest of such networks.

Next generation wireless networks will take advantage of the popularity and the data rates offered by unlicensed wireless networks such as WiFi (WirelessFidelity) or WiMAX (WorldwideInteroperabilityforMicrowaveAccess) to enhance cellular services Le. UMTS (Universal Mobile Telecommunication System). Although currently exist approaches that provide service mobility, they rely on the assumption that cellular operators also own or manage the WiFi/WiMAX networks. Nevertheless, in spite of the business-related and technical differences of network operators/service providers we consider that service mobility between cellular and independent unlicensed wireless networks is feasible. In this article we present the SIP embedded Attribute Certificates to enable service mobility in heterogeneous multi- operator wireless networks.

This paper describes a new vision for mobility management in next generation all IP networks. We evaluate the vertical-to-horizontal handover in the proposed integration architecture for the third generation wireless communication (3G) from one side and WLAN 802.11 from the other side. In this architecture, the inter-domain management IDM module introduced is modeled and analytically studied in order to evaluate the handover calls dropping probability and the call blocking probability in function of the access network bandwidth, number of users and the admission control strategy. In this scenario, if it is not possible to guide the handover to a different access network capable of providing the same QoS and context parameters, or in other words, if the vertical handover could not be performed, it will be guided horizontally. In this case, the user is guided to the same access technology, resulting in a vertical-to- horizontal handover. This handover management will decrease the handover dropping probability as well as the QoS degradation since the handover is "guided" to the next access network.

International audience

One of the major challenges for the wireless networks is related to efficient mobility management issue. In this paper, we propose a new micro-mobility management scheme, called Micro Mobile MPLS, that supports both mobility and quality-of-service (QoS) management in cellular networks. Our proposal includes two protocol variants. In the first variant, called FC-Micro Mobile MPLS, the forwarding chain (FC) concept is provided to track efficiently the host mobility within a domain. This concept fits mobile nodes (MNs) with high mobility rate. The second protocol variant, called Master Forwarding Chain (MFC)-Micro Mobile MPLS, aims to reduce the total signaling cost by controlling the number of registration updates with the root of the domain. In order to assess the efficiency of our proposals, the aforesaid protocols are compared with respect to the existing solutions. To achieve this, we develop analytical models to evaluate both registration updates and link usage costs. Numerical and simulation results show that the proposed mechanisms can significantly reduce the registration updates cost and provide low handoff latency and packet loss rate under various scenarios.

In this paper, we propose an analytical approach to study the handoff performance of a wireless system with a new micro-mobility support called Micro Mobile MPLS. Our scheme includes two protocol variants. First, the fast handoff process, which anticipates the LSP procedure setup with an adjacent neighbor subnet that an mobile node (MN) is likely to visit, is provided to reduce service disruption. Second, a new mechanism based on the forwarding chain concept is proposed to track efficiently the host mobility whithin a domain. This concept can significantly reduce the registration updates cost and provide low handoff latency and packet loss rate. Analytical models, which capture the mobility behavior of an MN, are developed for cost analysis. Numerical and simulation results are given to justify the benefits of our proposed mechanisms.

Since the early nineties, wireless communications grew substantially in our societies to satisfy the latent need for mobile communications, with the main focus being communicate "whenever and wherever" one wants. Many protocols were proposed, of which 2.5G GSM/GPRS (Global System for Mobile Communications / General Packet Radio Service) and 3G UMTS (Universal Mobile Telecommunication Systems) as wide expensive network architectures and the IEEE wireless suite that aims to provide low cost wireless connectivity. Today, it seems obvious that both architectures, combined together, would lead to the best resource utilization, the greatest field cover at the lowest cost of installation. In this paper, we are interested in using Wireless Local Area Networks (WLANs) as access networks for the UMTS. We introduce a new WLAN protocol with hybrid properties based on 802.11e in order to comply with the strict Quality of Service (QoS) UMTS uses for its flows. It aims to fill the weaknesses of 802.11e in terms of delay adaptation with this 3G network.

Multi-protocol label switching (MPLS) is deployed in the Internet backbone to support service differentiation and traffic engineering. In recent years, there has been an interest to extend the MPLS capability to the wireless access networks for mobility management support. In this paper, we present an analytical approach to study the handoff performance of a wireless system with a new micro-mobility support called micro mobile MPLS. Our scheme includes two protocol variants. In the first variant called FH-micro mobile MPLS, we consider the fast handoff mechanism, which anticipates the LSP procedure setup with an adjacent neighbor subnet that an mobile node (MN) is likely to visit. This mechanism is proposed to reduce service disruption by using the link-layer (L2) functionalities. In the second variant called FC-micro mobile MPLS, the forwarding chain concept, which is a set of forwarding path, is provided to track efficiently the host mobility within a domain. This concept can significantly reduce the resource reservation cost, the registration updates cost and provide low handoff latency. Analytical models, which capture the mobility behavior of an MN, are developed for cost analysis. Numerical and simulation results are given to justify the benefits of our proposed mechanisms

One of the major challenges for the wireless networks is related to efficient mobility management issue. In this paper, we propose a new micro-mobility management scheme, called micro mobile MPLS, that supports both mobility and quality-of-service (QoS) management in cellular networks. Our proposal includes two protocol variants. In the first variant, called FC-micro mobile MPLS, the forwarding chain (FC) concept is provided to track efficiently the host mobility within a domain. This concept fits mobile nodes (MNs) with high mobility rate. The second protocol variant, called master forwarding chain (MFC)-micro mobile MPLS, aims to reduce the total signaling cost by controlling the number of registration updates with the root of the domain. In order to assess the efficiency of our proposals, all underlying protocols are compared through simulations using both two-dimensional (2-D) and one-dimensional (1-D) mobility models. Simulation results show that our proposed mechanisms can significantly reduce the registration updates cost and provide low handoff latency and packet loss rate under various scenarios

In this paper, we propose a practical approach to address how micro-mobility can be provided in an efficient way with continuous quality of service (QoS) support. Our proposal is based on multiprotocol label switching (MPLS) and mobile IP and relies on two-level hierarchy architecture. It supports two protocol variants. First, the fast handoff process, which anticipates the LSP procedure setup with an adjacent neighbor subnet that a mobile node (MN) is likely to visit, is provided to reduce service disruption. Second, a new mechanism based on a master forwarding chain concept is proposed to track efficiently the host mobility within a domain. Our concept can significantly reduce the total signaling cost and provide low handoff latency. This can be achieved by dynamically controlling the number of registration updates with the root of the domain according to a cost comparison. Analytical models are developed and simulations are conducted to justify the benefits of our proposed mechanisms

This article presents the micro mobile MPLS scheme, which is a new proposal for IP local mobility in wireless MPLS access networks. Our proposal is based on multiprotocol label switching (MPLS) and mobile IP and relies on two-level hierarchy architecture. With micro mobile MPLS, mobile nodes (MNs) do not require changes to their IP protocol stack, neither for micro-mobility nor macro-mobility. Nevertheless, it still uses Mobile IP for macro-mobility scenarios. The main features of our scheme are related on scalability, flexibility, fast handoff and the ability to provide quality of service (QoS) by using the underlying MPLS traffic engineered paths. Simulation results are given to justify the benefits of our proposed architecture.

In this paper, we propose a practical approach to address how micro-mobility can be provided in an efficient way with continuous quality of service (QoS) support. Our proposal is based on multiprotocol label switching (MPLS) and mobile IP and relies on two-level hierarchy architecture. It supports two protocol variants. First, the fast handoff process, which anticipates the LSPs procedure setup with the neighboring locations where a mobile node (MN) may move to, is provided to reduce the service disruption. Second, a new mechanism based on the forwarding chain concept is proposed to track efficiently the host mobility within a domain. This concept can significantly reduce the registration updates cost and provide low handoff latency. Analytical models are developed and simulations are conducted to justify the benefits of our proposed mechanisms

The paper proposes a new fast algorithm to evaluate the probability distribution function (PDF) of link delay over time by using network tomography techniques. Once we have the delay distribution, we can adapt the route of the flows between a source and its destination so that the end-to-end path is always the one that offers the least mean delay and a probability of exceeding a critical value smaller than a predefined threshold. Our mechanism, which guarantees the use of the path minimizing the end-to-end delay, is best implemented in the core network of a wireless domain. As the network tomography introduces additional flows, our mechanism is more adapted to wired peer ends, e.g. base stations, domain gateways, etc. With MPLS (multi protocol label switching) to create and maintain the routes, we validated our contribution using the Network Simulation simulator, ns2.

The paper characterizes the statistical distribution of the interarrival packet time of UTRAN traffic at the SAP level of the MAC layer. We analyze a simulated traffic trace of UMTS networks to characterize the nature of the aggregated flows. We chose MMPP-2 (Markov modulated Poisson process) to model the packet interarrival time.

We are interested in allocating resources on the up/down link UDL of a low earth orbit LEO satellite constellation. Radio links constitute a scarce resource that needs to be shared efficiently between different users with different needs. In this paper, two service classes are considered: real time voice service and non real time data service. A mixed service at the burst level for voice and at the packet level for data is considered. This is motivated by the fact that a service at the call level appears to be a waste of bandwidth for the voice class. As for data, the sporadic nature of this service justifies the packet level service. Queues are associated with each class. Access to the channel is assumed to be structured into frames and the movable boundary MB approach is applied in order to separate, on the basis of the ongoing voice bursts as well as the queues' occupation level, each frame into two compartments associated each with the service of each of the classes. The purpose of this approach is to accommodate a greater number of communications while respecting the quality of service QoS requirements.

The up/down link UDL of a low Earth orbit LEO satellite constellation is a scarce resource that needs to be shared efficiently between different users with different needs. Serving requests at the call level appears to be bandwidth wasteful since resources are still allocated to a communication even during silence periods. A burst level service appears to be a more appropriate one in order to increase resources utilization. In the context of this study, three service classes are considered: voice service, a real time service with very strict constraints over the delay and the bandwidth, data service with guarantees but with less stringent requirements than what is required for voice, and best effort service with no guarantees requirements. A new form of movable boundary approach is used in order to accommodate a greater number of communications of each class, while respecting quality of service QoS requirements.

Provision of various real time multimedia services to mobile users is the main objective of the next generation wireless networks, which will be IP-based and are expected to interwork with the Internet backbone seamlessly. Two major challenges in IP-based wireless mobile networks are support of fast handoff and provision of quality of service (QoS). In order to provide QoS to the mobile users, we propose to study the performance of a distributed call admission control (CAC) in a cellular IP domain. This scheme is compared to a centralized CAC performed by the domain gateway. The proposed CACs are part of a dynamic adaptive architecture DYNAA that copes with users' mobility and that dynamically adapts the calls bandwidth.

The focus of this paper is the performance of the AAL2/ATM transport technology for the Universal Terrestrial Radio Access Network (UTRAN) in UMTS/IMT2000. We particularly consider the case of voice and data streams, with a service differentiation between them conducted at the AAL2 level by the use of the weighted round robin (WRR) scheme. We obtain closed-form expressions for bounds on the delay violation probabilities for both voice and data frames, taking into account the impact of WRR as well as the traffic patterns inherent to UMTS.

The third generation UMTS (Universal Mobile Telecommunication System) provides worldwide multimedia wireless services in a host of environments encompassing indoor picocells to satellite megacells. The UMTS and satellite-UMTS consists of two modes, a frequency division duplex (FDD) mode and a time division duplex (TDD) mode. The agreement recommends the use of wideband code division multiple access (WCDMA) for FDD mode and time division-code division multiple access (TD-CDMA) for TDD mode. A modified CDMA/PRMA (code division multiple access/packet reservation multiple access) protocol for LEO (low earth orbit) satellite system that we proposed previously is presented and an analytical model for CDMA/PRMA in LEO satellites is worked out. The proposed protocol is a modified CDMA/PRMA that adapts to the TD-CDMA mode for LEO satellite used in UMTS. An analytical computation is presented in order to determine the main parameters that influence the protocol and to choose the best of them. The goal is to have a statistical multiplexing that uses resources (slots defined both in time and code domain) as efficiently as possible. Analytical results are then validated by simulations, which give an additional proof of the efficiency of our protocol.

This paper studies an adaptive CDMA/PRMA protocol for satellite LEO systems. The new protocol is called S-CDMA/PRMA (satellite-code division multiple access/packet reservation multiple access). The goal is to integrate several types of traffic (voice, file transfer and Web) on the channel. This leads to a service multiplexing and resource allocation study. New permission probability control functions are defined to give priority to voice traffic in order to guarantee its QoS. As a first step, we propose an analytical model for voice and file transfer data to calculate their performance. As Web traffic is very complicated to be studied analytically, we studied it by simulation. A simulation multiplexing several traffic types is also presented. The essential performance parameters are the loss probability for voice users and the waiting time for data users.

The focus of this paper is the performance of ATM/AAL2 as a transport technology for Universal Terrestrial Radio Access Network (UTRAN) in UMTS/IMT-2000 setting. In this work, we propose an analytical model for the transparent multiplexing and transport through UTRAN of several voice channels onto a single AAL2/ATM VC. We investigate the queue building up at the AAL2 multiplexer in order to derive some characteristics of the sojourn time of voice frames within the UTRAN. Our results quantify the performance of AAL2/ATM-based transport of voice in terms of mean queue at the multiplexer, mean sojourn time and delay violation probability within the UTRAN.

This paper studies an adaptive CDMA (code division multiple access) protocol for satellite LEO (low Earth orbit) systems. The new protocol is called S-CDMA (satellite-CDMA). The goal is to integrate several types of traffic (voice and datal) on the channel. This leads to service multiplexing and resource allocation study. New permission probability control functions, are defined to give priority to voice users in order to guarantee its QoS. Resource allocation strategies are studied and compared. A simulation multiplexing the two traffic types is presented in order to determine the best multiplexing technique. The essential performance parameters are the loss probability for voice and data users and the waiting time for data users.

We study a multi-service connection admission control (CAC) policy and we derive the corresponding resources allocation (RA) mechanism to access the up/down link (UDL) in a low Earth orbit (LEO) satellite constellation used as an access network to a mobile terrestrial network. We propose the usage of a trunk reservation policy for bandwidth reservation that allows the network to route the call on the satellite where the blocking probability is a minimum. In our study, we assume that the network handles three types of call: real time voice calls, non-real time data calls with guaranteed bandwidth and non-real time elastic data calls. A Markovian modelling approach is used to analyse the bandwidth occupation and derive the analytical model for the RA scheme.

We present a new concept for multicast group management called contractual group membership or CGM. The main idea behind this concept is the division of the receiver group into homogeneous subgroups. This division is based on physical conditions or/and QoS criteria like available bandwidth, delay, loss probability, ... . The sender will carry a separate conversation with each subgroup using the scalable reliable multicast protocol (SRMTP). We define a multidimensional distance factor to evaluate the logical distance between the members of a group in order to split this group into homogeneous subgroups. The dimensions of this distance factor are end-to-end bandwidth, delay, and loss rate. ESRMTP is an extended version of SRMTP that we have developed in order to support our new distance factor. The simulation results that we have obtained using the three dimensional distance factor with ESRMTP show that the bandwidth splitting is very important for increasing the average throughput of the multicast session and to minimize the average end-to-end delay. It shows as well that the delay and loss probability splitting decrease the jitter for each receiver which is very important for real-time applications. In addition to jitter minimization, loss rate splitting plays a key role in minimizing the network load caused by the FEC integrated in ESRMTP, due to the possibility of controlling the amount of FEC overhead as a function of the loss rate.

In this paper, several TDMA-based packet multiple access protocols are studied and evaluated in the geostationary satellite environment. The distributed queueing random access protocol, DQRAP, originally proposed for HFC networks is adapted to the satellite environment. Another protocol, the announced retransmission random access protocol, ARRA, proposed for wireless networks is also studied. Both protocols are modeled and simulated in a VSAT network context. We then propose a new protocol which combines the advantages of both studied schemes and is more adapted to interactive multimedia applications over satellite uplinks. The generalized retransmission announcement protocol, GRAP, regroups the immediate access by contention at low loads, and the reservation access. At higher loads, to achieve a better channel efficiency. An analytical model is proposed to calculate the channel throughput obtained by GRAP under different loading conditions. Simulation results illustrate an improved throughput/delay characteristics and a higher protocol stability compared to both DQRAP and ARRA. Enhanced versions of the protocol are also proposed and evaluated to further improve its efficiency, with reasonable additional complexity.

Multiple access to the radio channel is a very important aspect that determines the efficiency of wireless networks. In this paper, we propose a packet multiple access protocol for uplink satellite channels characterized by their long propagation delay. The generalized retransmission announcement protocol, GRAP relies on a framed channel structure, allowing user access by either direct contention or reservation. This hybrid access scheme is proven to be more efficient in following the dynamic load variations of the satellite system. The different features and operation of GRAP are explained in this paper. An analytical model is developed to calculate the numerical channel throughput achieved by GRAP for different traffic loads.

This work focuses on resource allocation and connection admission control (CAC) issues in broadband satellite networks. Broadband services can now be provided by satellite systems operating in the Ka band, due to the large bandwidth available at such frequencies. In this context, we propose a resource allocation algorithm which integrates three classes of services at the MAC layer: constant bit rate (CBR), bursty data, and best effort services. The double movable boundary strategy (DMBS) is proposed to establish a resource-sharing policy among these service classes over the satellite uplink channel. The DMBS is a dynamically controlled boundary policy which adapts the allocation decision to the variable network loading conditions. Connection-oriented and connectionless services can be supported by the system. The CAC and slot allocation decisions are taken at the beginning of each control period after monitoring the filling level of traffic request queues. A threshold level for the bursty data request queue is defined to regulate the CAC process. The impact of the queue threshold value on the performance of the DMBS allocation policy is particularly evaluated in this study. A dynamic variation of this value is also proposed to enhance the system response to interactive applications. We present a brief analytical formulation for the DMBS model, together with simulation study details and performance evaluation results. The obtained results indicate a good efficiency, in terms of overall channel throughput and CBR blocking probability, for both fixed and dynamic data queue threshold approaches. The dynamic approach, however, outperforms the fixed one in terms of overall encountered bursty data delay.

In this paper the impact of the usage parameters control (UPC) parameters on a dynamic bandwidth allocation scheme is investigated for the transmission of MPEG video traffic. This is a analyzed assuming a self-conformance check by the source so as to avoid the transmission of non-conformant traffic that risks being discarded. This control is integrated within the implementation of a periodic allocation protocol which allows simultaneous coding (in the source) and reservation (in the network). The results of MPEG-1 traces show that for higher loading conditions the UPC parameters interfere with the allocation scheme in a way that degrades the performance. Further, an over-average degradation of more important traffic (belonging to I frames) can be eliminated by applying internal selective discarding.

The movable-boundary integrated CBR/bursty-data traffic, MB-ICBT, is a new version of hybrid protocols supporting both, circuit- and packet-switching techniques in VSAT network environments. Circuit-switching is applied to CBR traffic connections, which are admitted in the system on a DAMA basis. Bursty-data traffic, on the other hand, is allowed to contend randomly, sending simultaneously an anticipating reservation. A movable boundary policy is applied between the two traffic compartments to adapt to network loading conditions. The introduction of the anticipated reservation access for bursty-data, together with the movable-boundary policy, serve to minimize the collision resolution delay, largely significant in VSAT networks. The MB-ICBT protocol is analysed and simulation results verify the enhanced performance in terms of access delay for bursty-data traffic together with an improved overall channel throughput.

A periodic allocation protocol, called anticipated traffic allocation protocol (ATAP) for real time VBR traffic is proposed. The main objective of this protocol is to dynamically allocate the available bandwidth to real-time VBR sources, i.e. to be more efficient than the CBR allocation and at the same time more secure that the "walk-in" allocation. The ATAP unit is located at the network entry node between the real-time encoder and the applied bandwidth allocation protocol in the network, the fast reservation protocol FRP/DT. This reservation protocol cannot satisfy the real-time requirements, since the source would have to wait at least a round trip delay to reserve a required bandwidth increase. Hence, the ATAP proposes to anticipate and allocate the bandwidth one period in advance. This permits the encoder to adjust its coding bit rate according to the network loading condition. Doing so, a congestion will gracefully degrade the subjective quality of the signal, instead of "blindly" loosing cells at the network entry node. A minimum bit rate negotiated at the connection set-up is always guaranteed to assure the connection continuity in the case of the case of bandwidth reservation refusal. On the network side, the ATAP interacts with the FRP/DT. Reservation failures are used as congestion indicators to control the entering traffic and to adjust the cell priority. A simulation analysis investigates the performance of the ATAP and its interaction with the FRP/DT for two real MPEG VBR audio sequences under different bit rate anticipation approaches.

Multimedia traffic is a special traffic consisting of different components (video, voice and data) belonging all to the same application and hence being strictly temporarily bounded. The jitter impact on multimedia (MM) traffic in ATM networks is analyzed. The inter-flows jitter (IFJ) parameter, that defines the jitter between several associated traffic flows is introduced. Furthermore, the jitter and IFJ are studied under two different multiplexing schemes namely, "all in one virtual path (VP)" and "one VP for each". An IFJ recovery mechanism (IFJ-rm) is finally proposed to restore the original traffic. Simulation results for the IFJ-rm under different scheduling disciplines are presented and discussed.

A media access control (MAC) layer protocol called S++, which offers several features that are desirable for gigabit per second local area networks, is described. The performance of the protocol has been investigated by detailed simulations which have been confirmed using an analytical model. A number of results that show how S++ offers consistently lower mean delays than the distributed queue dual bus (DQDB) protocol when used on a folded bus network are presented. Further results illustrate additional properties, which include the provision of pseudopriorities, a reduction in message reassembly time compared with DQDB, and the rapid redistribution of bandwidth under varying loads.>