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A massive increase in the number of mobile devices and data-hungry vehicular network applications creates a great challenge for mobile network operators (MNOs) to handle huge data in cellular infrastructure. However, due to fluctuating wireless channels and high mobility of vehicular users, it is even more challenging for MNOs to deal with vehicular users within a licensed cellular spectrum. Data offloading in the vehicular environment plays a significant role in offloading the vehicle’s data traffic from congested cellular network’s licensed spectrum to the free unlicensed WiFi spectrum with the help of roadside units (RSUs). In this article, an intelligent reward-based data offloading in the next generation vehicular networks (IR-DON) architecture is proposed for dynamic optimization of data traffic and selection of intelligent RSU. Within the IR-DON architecture, an intelligent access network discovery and selection function (I-ANDSF) module with $Q$ -learning, a reinforcement learning algorithm is designed. The I-ANDSF is modeled under a software-defined network (SDN) controller to solve the dynamic optimization problem by performing an efficient offloading. This increases the overall system throughput by choosing an optimal and intelligent RSU in the network selection process. The simulation results have shown the accurate network traffic classification, optimal network selection, guaranteed quality of service, reduced delay, and higher throughput achieved by the I-ANDSF module.

In this paper, we design an enhanced access network discovery and selection function (ANDSF), named E-ANDSF, which provides previous mobile access gateway (PMAG) with information for base station selection, and propose an improved IP-based handover/offload scheme, called I P-based H andover/offload system assisted by E - A N D SF (IHEAD), which invokes multilayer perceptron, a machine learning technique, to select a base station for user equipment to handover or offload network traffic to wireless local area network (WLAN). The purpose is improving network service quality with the assistance of stream control transmission protocol and E-ANDSF. Experimental results show that the IHEAD outperforms those tested schemes.

As mobile applications and services have developed, the dramatic growth in user data traffic has led to the legacy channels becoming ever more congested with the commensurate requirement for more spectrum. This has motivated both regulatory bodies and industry to investigate innovative strategies to increase the existing spectral efficiency. Prominent examples include both Long Term Evolution (LTE) which employs orthogonal frequency-division modulation technology to improve bandwidth efficiency, and heterogeneous networks, which facilitate the offloading of data traffic between technologies such as from LTE to Wi-Fi and vice versa. Furthermore, as 5G mobile technology and related standards mature, there is an impetus to address the issue of secondary user (SU) spectrum access in which TV White Space (TVWS) is the prime contender. Two nascent viewpoints have emerged as to how this will evolve: i) greater coverage, ii) increased throughput allied with lower latency. This paper presents a novel TVWS framework that successfully fulfils both criteria to ensure 5G services can both exploit TVWS spectrum and protect the benefits of SU access and quality-of-service provision by using a routing strategy on the Access Network Discovery and Selection Function server to dynamically determine the most suitable heterogeneous technology for the new framework.

Vehicle-to-infrastructure (V2I) communication enables a variety of applications and services, including safety, infotainment, mobility, payment, and so on, to be accessed and consumed. However, V2I requires seamless connectivity without having to worry about transitions between and across heterogeneous networks. In the next generation 5G heterogeneous networks (HetNet), which is a combination of multi-tier and multi-radio access technologies (RAT), the main challenges for V2I communication are having better network discovery, selection, and implementation of fast, seamless, and reliable vertical handover; maintaining QoS; and providing better quality of experience (QoE). To meet these challenges, considerable research contributions exist, and various generic solutions have also been proposed. In this chapter, the authors discuss the state-of-the-art of such technologies and V2I communication that consists of available radio access technologies, handover management, access network discovery and selection function (ANDSF), and media-independent handover (MIH)-based standard solutions for vertical handover. Besides, the chapter presents associated challenges with these technologies and highlights the possible research directions on multi-path technologies, SDN-based solutions, hybrid solutions, and 5G-enabled internet of vehicles (IoV). Primarily, the chapter discusses seamless V2I connectivity in HetNet and presents the state-of-the-art and future research directions in this domain.

In this paper, we propose a framework for cross-layer optimization to ensure ultra-high reliability and ultra-low latency in radio access networks, where both transmission delay and queueing delay are considered. With short transmission time, the blocklength of channel codes is finite, and the Shannon Capacity cannot be used to characterize the maximal achievable rate with given transmission error probability. With randomly arrived packets, some packets may violate the queueing delay. Moreover, since the queueing delay is shorter than the channel coherence time in typical scenarios, the required transmit power to guarantee the queueing delay and transmission error probability will become unbounded even with spatial diversity. To ensure the required quality-of-service (QoS) with finite transmit power, a proactive packet dropping mechanism is introduced. Then, the overall packet loss probability includes transmission error probability, queueing delay violation probability, and packet dropping probability. We optimize the packet dropping policy, power allocation policy, and bandwidth allocation policy to minimize the transmit power under the QoS constraint. The optimal solution is obtained, which depends on both channel and queue state information. Simulation and numerical results validate our analysis, and show that setting packet loss probabilities equal is a near optimal solution., Comment: The manuscript has been accepted by IEEE transactions on wireless communications

The rapid development and integration of heterogeneous wireless networks provide ubiquitous communications for mobile users. The intelligent and multimodal mobile terminals should select the best access network at any time anywhere. However, the “best” is a complex and fuzzy concept, which has different meanings to different users and even to the same user under different conditions. There are various factors to consider when deciding which one is the best for a mobile terminal. In this paper, we design a generalized and flexible framework for the access network selection in heterogeneous wireless networks. The framework is generalized because it considers various factors in a comprehensive way to get the solutions. These factors can be classified as network-related or user-related, economic or non-economic, objective or subjective, accurate or fuzzy. Meanwhile, the framework is also flexible because these factors can be customized and adapted to specific solutions. Under the framework, given N mobile terminals and M access networks, we have developed a novel access network selection scheme based on a Quantum-inspired Immune Clonal Algorithm (QICA). Experimental results demonstrate that our proposed scheme provides better utilities for both the users and the access networks, and also better services for users as compared with four other schemes.

Increasing the capacity of wireless cellular network is one of the major challenges for the coming years. A lot of research works have been done to exploit the ultra-wide band of millimeter wave (mmWave) and integrate it into future cellular networks. In this paper, to efficiently utilize the mmWave band while reducing the total deployment cost, we propose to deploy the mmWave access in the form of ultra-high capacity mmWave gates distributed in the coverage area of the macro basestation (Macro BS). Delayed offloading is also proposed to proficiently exploit the gates and relax the demand of deploying a large number of them. Furthermore, a mobility-aware weighted proportional fair (WPF) user scheduling is proposed to maximize the intra-gate offloading efficiency while maintaining the long-term offloading fairness among the users inside the gate. To efficiently link the mmWave gates with the Macro BS in a unified cellular network structure, a cloud cooperated heterogeneous cellular network (CC-HetNet) is proposed. In which, the gates and the Macro BS are linked to the centralized radio access network (C-RAN) via high-speed backhaul links. Using the concept of control/user (C/U) plane splitting, signaling information is sent to the UEs through the wide coverage Macro BS, and most of users’ delayed traffic is offloaded through the ultra-high capacity mmWave gates. An enhanced access network discovery and selection function (eANDSF) based on a network wide proportional fair criterion is proposed to discover and select an optimal mmWave gate to associate a user with delayed traffic. It is interesting to find out that a mmWave gate consisting of only 4 mmWave access points (APs) can offload up to 70 GB of delayed traffic within 25 sec, which reduces the energy consumption of a user equipment (UE) by 99.6 % compared to the case of only using Macro BS without gate offloading. Also, more than a double increase in total gates offloaded bytes is obtained using the proposed eANDSF over using the conventional ANDSF proposed by 3GPP due to the optimality in selecting the associating gate.

It is expected that in the very near future, cellular networks will have to deal with a massive data traffic increase, as well as a vast number of devices. Optimal placement of the end devices to the most suitable access network is expected to provide the best Quality of Service (QoS) experience to the users but also the maximum utilization of the scarce wireless resources by the operators. Several on-going proposals attempt to overcome the existing barriers by enabling the use of Wi-Fis and femto-cells to cater for part of the load generated by the end devices. The evolution of the Access Network Discovery and Selection Function (ANDSF) for the core part of the cellular network, as well as the Hotspot 2.0 approach, are currently being subject to thorough discussions and studies and are expected to facilitate a seamless 3GPP-WiFi interworking. During the past years, several Radio Access Technology (RAT) selection schemes have been proposed. However, these schemes do not take into consideration the opportunities offered by these new standardized approaches. Our paper acts in a manifold way: Firstly, it proposes COmpAsS, a Context-Aware RAT Selection mechanism, the main part of which operates on the User Equipment (UE)-side, minimizing signaling overhead over the air interface and computation load on the base stations. Secondly, we discuss in detail the architectural perspective; i.e., the extensions needed in the network interfaces that enable the exchange of the required context information among the respective network entities and in accordance with the 3GPP trends in relation to the context-aggregating entities. Furthermore, we quantify the signaling overhead of the proposed mechanism by linking it to the current 3GPP specifications and performing a comprehensive per-parameter analysis. Finally, we evaluate the novel scheme via extensive simulations in a complex and realistic 5G use case, illustrating the clear advantages of our approach in terms of key QoS metrics, i.e. the user-experienced throughput and delay, both in the uplink and the downlink.

Mobile data offloading using unlicensed WiFi spectrum represents one of the innovative approaches that can be adopted to cope with the huge amount of mobile traffic demand. However, the main challenge in such approach lies in the ability of the system to discover the WiFi coverage for users who may need to offload their data. For this, the access network discovery and selection function (ANDSF) has been introduced by 3GPP to provide the mobile user equipment (UE) with the discovery information and the list of available WiFi hotspots. However, the current ANDSF discovery mechanism depends on the geographical location of the UE, which need to be accurately determined and continuously transmitted to the ANDSF server. In this paper, an enhanced ANDSF WiFi discovery technique is proposed and validated. The proposed technique is designed to use the reference signal received power (RSRP) information measured at UEs from their surrounding cellular base stations to build fingerprints for various WiFi hotspot areas. Based on the constructed fingerprints, the UE's WiFi coverage state can be identified using the proposed decision tree (DT) machine learning approach. The conducted tests and generated results validate the operation and performance of the proposed machine learning-based discovery technique with accuracy reaches up to 95%.

Seamless mobility management is considered as an important cornerstone of fifth generation (5G) networks. In fact, it is considered as one of the requirements for the next generation all-IP to fulfill their services in real-time. It allows devices and users to maintain highly seamless connectivity by switching between multiple wireless network using Vertical HandOver techniques (VHO). To address this need, some mobility management solutions have been proposed by researchers in order to support the VHO of devices using the Proxy Mobile IPv6 (PMIPv6) protocol. However, these solutions suffer from lack of security. For that, a new secure protocol, called Secure Fast PMIPv6 for Vertical HandOver (SFPMIPv6-VHO), is proposed in this paper. The proposed schema ensures a strong authentication in the case of the VHO between the Evolved Packet System (EPS) of Long Term Evolution (LTE) and the Wireless Fidelity (WIFI) using FPMIPv6 protocol. In addition, it suggested the integration of the Access Network Discovery and Selection Function (ANDSF) to perform an authentication preparation of user equipment (UE) in the selected network due to the limits of discover heterogeneous networks in the case of the PMIPv6 protocol. Our proposed protocol is modeled and validated using the tools of Automated Validation of Internet Security Protocols and Applications (AVISPA) and Security Protocol Animator for AVISPA (SPAN). The results of our simulations indicate that our protocol is robust against various attacks and that responds to our goals.

The continuous increase of mobile data traffic volume creates new challenges for telecommunication network operators. As a possible solution, many traffic offloading techniques have been proposed. In parallel, there is a trend to handle all the access techniques under the umbrella of IP, including non-3GPP networks (e.g., Wi-Fi), mainly with the help of IPv6. In this paper we provide a new architectural proposal in Evolved Packet Core (EPC) described as flow-based and operator-centric dynamic mobility management with Proxy Mobile IPv6 (PMIPv6). This new approach is supported by current EPC entities including Policy and Charging Rules Function (PCRF), Access Network Discovery and Selection Function (ANDSF), and Local Mobility Anchor (LMA) and by defining a novel communication scheme between them. The proposal was evaluated in a virtual testbed environment, and measurements based simulations were carried out where the solution showed significant benefits by enhancing operator flexibility, increasing user experience, and decreasing signaling overhead due to its highly dynamic operation and optimized flow-level behavior.

The preliminary credibility assessment screening system (PCASS) is a US-based program, which is currently being implemented by intelligence units of the North Atlantic Treaty Organization (NATO) to make the initial screening of individuals suspected of infiltrating the Afghan National Defense and Security Forces (ANDSF). Sensors have been instrumental in the PCASS, leading to organizational change. The aim of this research is to describe how the ANDSF adapted to the implementation of PCASS, as well as implemented changes since the beginning of the program. To do so, we have conducted a qualitative, exploratory, and descriptive case study that allows one to understand, through the use of a series of data collection sources, a real-life phenomenon of which little is known. The results suggest that the sensors used in PCASS empower security forces with reliable technologies to identify and neutralize internal threats. It then becomes evident that the technological leadership that PCASS provides allows the developing of a relatively stable and consistent organizational change, fulfilling the objectives of the NATO and the ANDSF. info:eu-repo/semantics/publishedVersion

Device discovery is an integral part of Device-to-Device communications and a key prerequisite for the introduction of proximity-aware services in Long Term Evolution (LTE) networks. In this concept, we provide a comprehensive study on device discovery protocols and we examine the key design aspects towards an LTE-tailored device discovery. We give insights into the radio access approach that can be used for device discovery, considering in-coverage synchronized devices that exploit a dedicated spectrum portion to discover each other. Useful remarks on the optimal theoretical performance in terms of the number of required discovery transmissions and time-slots are presented, while comparative simulation results for various radio access approaches are provided.

From the perspective of a single user, concurrent utilization of all available radio access technologies (RATs) is always beneficial for increasing individual data rate. However, given the interactions among users, occupying multiple RATs at each user might not be optimal from a network-wide viewpoint. In this paper, we explore the answer to the posed question what is the optimal access strategy in multi-RAT cellular networks, solving a distributed RAT access control problem for maximizing network throughput. With stochastic geometry, we analytically evaluate network throughputs for two different access modes: 1) single RAT access (altruistic access) and 2) simultaneous multiple RATs access (selfish access). Comparing the network throughputs for the two modes, we first show that the network throughput can be maximized by properly mixing the two access modes and then derive the optimal portions of each mode in a network, which motivates a distributed RAT access control in a probabilistic sense. The optimal mixture of the two modes controls scheduling contention and interference among users to maximize the network throughput. We also analyze the effects of various system parameters, such as the number of frequency sub-bands for each RAT, user density, and access point density, on the optimal portions of the two access modes.

The management of Vertical Handovers (VHO) in a heterogeneous networks (HetNet) environment has received considerable attention, with the aim of enabling effective, context-aware network selections. Various relevant architectures and frameworks have been proposed, but the available methodologies for evaluating the performance of these proposals and for comparing alternatives are still limited. In addressing this issue, the paper contributes a versatile modeling methodology that focuses on signaling in the handover preparation phase and incorporates all significant effects that are associated with the exchange, queueing and processing of the signaling messages and have an impact on delay-related performance. The resulting model is comprehensive, yet capable of admitting closed form solutions. Even more importantly, the methodology is generic and can be flexibly tailored to different VHO architectures. To demonstrate this feature, the paper applies the modeling methodology in two context-aware VHO approaches that differ in the way of acquiring dynamic resource availability context. The first approach is according to standards-based recommendations (such as the IEEE 802.21 Media Independent Handover Function (MIHF) and the 3GPP Access Network Discovery and Selection Function (ANDSF)) and obtains resource availability context reactively, each time a handover is triggered, through interaction between the serving network (SN) and every candidate network (CN). The other approach aligns with recent research directions and introduces a local context repository that gathers proactively, in a periodical fashion, the resource availability context from the various Radio Access Networks (RANs) associated with this repository, reducing the signaling overhead and enabling a potentially prompter discovery of a proper network target. For both approaches, the model-based results are validated against simulations, confirming the effectiveness and the accuracy of the modeling methodology. Furthermore, the model-based results enable a direct performance comparison of the two approaches, demonstrating that the proactive architectural approach can provide significant performance and processing efficiency gains, in comparison to the reactive approach.

As the demand for broadband services continues to grow worldwide, traditional solutions, such as digital cable and fiber optics, are often difficult and expensive to implement, especially in rural and remote areas. The emerging WiMAX system satisfies the growing need for high data-rate applications such as voiceover IP, video conferencing, interactive gaming, and multimedia streaming. WiMAX deployments not only serve residential and enterprise users but can also be deployed as a backhaul for Wi-Fi hotspots or 3G cellular towers. By providing affordable wireless broadband access, the technology of WiMAX will revolutionize broadband communications in the developed world and bridge the digital divide in developing countries. Part of the WiMAX Handbook, this volume focuses on the standards and security issues of WiMAX. The book examines standardized versus proprietary solutions for wireless broadband access, reviews the core medium access control protocol of WiMAX systems, and presents carriers' perspectives on wireless services. It also discusses the main mobility functions of the IEEE 802.16e standard, describes how to speed up WiMAX handover procedures, presents the 802.16 mesh protocol, and surveys the testing and certification processes used for WiMAX products. In addition, the book reviews the security features of both IEEE 802.16 and WiMAX. With the revolutionary technology of WiMAX, the lives of many will undoubtedly improve, thereby leading to greater economic empowerment.

The Next Generation First Responders program, run by the Department of Homeland Security, is responsible for developing and applying technologies to assist emergency responders of the future. Deployable Systems (DS) are a key technology in this program as they are critical in providing coverage when the availability of wireless resources is impacted during major disasters, in locations experiencing congestion due to large-scale incidents, or in remote areas where complete coverage is not feasible. The Public Safety Communications Research group that is conducting research into DS technology has described technology gaps in•Measuring, modeling and predicting network coverage•Allocating, prioritizing, and routing available bandwidth between different applications•Interworking DS from different vendors•Determining the coverage and bandwidth DS can provideWe will show how these gaps can be addressed by implementing two 3rd Generation Partnership Project (3GPP) specifications - Access Network Discovery and Selection Function (ANDSF) and Self-Organizing Networks (SON) across the wireless and DS networks using a common data repository. Moreover, we will show how Machine Learning algorithms can leverage this data to implement many additional use cases that will help emergency responders, and disaster response planners in developing and implementing effective and efficient disaster management strategies.

Next Generation Cellular Networks (NGCN) envisions to provide ultra low latency, extremely high data rates (Gbps), massive and seamless connectivity. In order to meet these demands, NGCN is expected to deploy huge number of small cells (i.e. Femto cells, Pico cells & Micro cells) along with the current Macro LTE-A cells. Each NGCN cell is expected to consist of all the aforesaid type of cells supporting services like Device to Device (D2D) communications, Mobile Cloud Computing (MCC), Big Data, Internet of Things (IoT), Internet of Vehicles (IoV), etc. This in turn leads to proliferation of devices in the network supporting aforesaid heterogeneous services. On the other hand, the availability of different type of Next Generation Node B (gNBs) may vary dynamically based on event, time, location, weather conditions, load conditions etc. Therefore, it is necessary for UEs or smart devices to camp on to the appropriate gNB in order to avail un-interrupted and seamless services with high QoS and QoE. This article explores different use cases based on three dimensional axis of NGCN i.e. requirements, technologies and services, wherein the availability of gNBs vary depending on each use case. Furthermore, we explore the avenues of Access Network Discovery and Selection Function (ANDSF) node functionality to automate the congestion free network discovery and selection and help the devices to camp on to the optimal gNBs without the intervention of Mobile Network Operators (MNOs). We propose to enhance the legacy ANDSF capability by inducing a Data Analytics platform per virtual instance of PGW. Data analytics platform will make policies for ANDSF (assumed to be deployed in the same v-PGW) based on the use cases. The synergy of data analytics and ANDSF platform is scrutinized with the help of simulations performed with the help of real time cellular traffic traces in a dense urban area by a Korean operator in order to instill the effectiveness of our proposal.

Machine-to-machine (M2M) communications, also known as machine-type communications (MTC) in 3GPP LTE systems, provide autonomous connectivity between machines without human intervention to create new service, e.g., the Internet of Things and the smart grid. M2M communications normally involve a large number of MTC devices (MTCDs) to support a variety of sensor applications. Consequently, concurrent and massive access attempts of MTCDs to radio access networks (RANs) may cause intolerable delay, packet loss, and even service unavailability. In this paper, we propose a joint optimal physical random access channel (PRACH) resource allocation and access control mechanism to address the performance degradation caused by concurrent and massive access attempts of MTCDs in LTE systems. We define the notion of random access efficiency and formulate an optimization problem for maximization of the random access efficiency with random access delay constraint. We also propose a dynamic resource allocation and access control algorithm based on estimation of the number of MTCDs for a system with dynamically varying numbers of massive MTCDs. Then, an analytical model is provided using a discrete-time Markov chain for the proposed mechanism. The effectiveness of the proposed algorithm is demonstrated via analysis and simulations. The proposed algorithm was able to maintain the optimal random access efficiency while satisfying the average random access delay requirement of MTCDs to handle massive and dynamic MTCDs per cell.

A large number of new data-consuming applications are emerging, and many of them involve mobile users. In the next generation of wireless communication systems, device-to-device D2D communication is introduced as a new paradigm to offload the increasing traffic to the user equipment. Before the traffic transmission, D2D discovery and access procedure is the first important step which needs to be completed. In this paper, our goal is to design a device discovery and access scheme for the fifth generation cellular networks. We first present two types of device discovery and access procedures. Then we provide performance analysis based on the Markov process model. In addition, we present numerical simulation on the Vienna Matlab platform. The simulation results demonstrate the viability of the proposed scheme. Copyright © 2015 John Wiley & Sons, Ltd.

Global mobile data traffic consumption and usage continues to increase rapidly leading to congested networks. Currently, cellular networks are overloaded with mobile data traffic due to the rapid growth of mobile broadband subscriptions and the increasing popularity of diversified applications for smartphones with multiple wireless interfaces and the flat-rate pricing model of cellular networks. One possible practical solution to alleviate this problem is the offloading of mobile data traffic from the primary access technology to the WiFi infrastructure to gain extra capacity and improve the overall network performance. As the strategy what and when to offload data is non-trivial, it is of vital importance to develop novel algorithms to guide this process. This paper addresses solutions for network-controlled WiFi offloading in Long Term Evolution (LTE) cellular networks when performance needs exceed the capability of the LTE access. It then compares the performance of each access technology using different network performance metrics. In detail, an optimized signal-to-noise ratio-threshold based handover solution and extension to the 3rd Generation Partnership Project standard for Access Network Discovery and Selection Function (ANDSF) framework for WiFi offloading is proposed. Our simulation results have shown that ANDSF discovery can be used to control the amount of WiFi offloading.

In this paper, we propose a device-to-device (D2D) discovery scheme as a key enabler for a proximity-based service in the Long-Term Evolution Advanced (LTE-A) system. The proximity-based service includes a variety of services exploiting the location information of user equipment (UE), for example, the mobile social network and the mobile marketing. To realize the proximity-based service in the LTE-A system, it is necessary to design a D2D discovery scheme by which UE can discover another UE in its proximity. We design a D2D discovery scheme based on the random access procedure in the LTE-A system. The proposed random-access-based D2D discovery scheme is advantageous in that 1) the proposed scheme can be readily applied to the current LTE-A system without significant modification; 2) the proposed scheme discovers pairs of UE in a centralized manner, which enables the access or core network to centrally control the formation of D2D communication networks; and 3) the proposed scheme adaptively allocates resource blocks for the D2D discovery to prevent underutilization of radio resources. We analyze the performance of the proposed D2D discovery scheme. A closed-form formula for the performance is derived by means of the stochastic geometry-based approach. We show that the analysis results accurately match the simulation results.

The existing IEEE and 3GPP standards have laid the foundation for integrating cellular and WiFi network to deliver a seamless experience for the end-users when roaming across multiple access networks. However, in recent studies, the issue of making roaming decision and intelligently selecting the most preferable Point of Service to optimize network resource and improve end user’s experience has not been considered properly. In this paper, we propose a novel cellular and WiFi roaming decision and AP selection scheme based on state of the art, 3GPP TS24.312 and IEEE 802.11u, k standards. Our proposed scheme assists the mobile nodes to decide the right timing to make roaming decision and select preferable point of service based on the operator’s policies and real-time network condition. We also introduce our simulation model of a heterogeneous network with cellular and WiFi interworking as well as 3GPP ANDSF, TS24.312. It is a complete end-to-end system model from application to physical layer with considering user’s mobility and realistic traffic model. The proposed scheme outperformed the conventional WiFi selection scheme in terms of dynamically steering mobile node’s data traffic from macrocell to available Access Points. The proposed scheme increased the utilization and balanced the traffic load of access points and improved user’s experienced throughput.

Ubiquitous mobile communication requires increased capacity and appropriate quality guarantee for services. To meet these demands next-generation mobile network operators will deploy small cells next to conventional base station structure intensively to enhance capacity and service coverage for customers. Implementation of seamless handover between first tier (macrocell layer) and second tier (small cells) is one of the key challenges to fulfill the QoS requirements. In this paper we introduce the reader to the details of the handover procedure: information gathering, decision strategies and the base station exchange process. All these three phases face difficulties in multi-tier networks. High dense femtocell deployment makes handover related information gathering very hard, efficient handover decision mechanisms are vital to reduce the number of unnecessary handovers and avoid ping-pong effect. Last but not least base station exchange has to be accelerated to achieve appropriate system performance. Next a comprehensive survey of state of the art handover optimization solutions in 3GPP LTE/LTE-A Home eNodeB handover management is presented which includes the actual version of 3GPP LTE/LTE-A HeNB handover procedure.

The first wireless regional area network standard with a cognitive radio (CR) framework for a broadband fixed or mobile access is IEEE 802.22. This standard based at the concept of sensing and utilizing temporary vacant radio channel in the frequency range from 54 MHz to 862 MHz. The IEEE 802.22 WRAN architectures includes decentralized collection of data about power level and time-dependent spectrum availability with help of customer premise equipment (CPE). The CPE sojourn time at the IEEE 802.22 WRAN is a key performance index for a making decision about vertical handover (VHO) from a current wireless access network as 3GPP LTE to the 802.22 WRAN. This paper present the sojourn time procedure from IEEE 802.22 discovery by CPE to a new IP-session establishment on WRAN. A new integrated architecture is offered for a coordinate access network creation on the base of integrated 3GPP access network discovery and selection function (ANDSF) and IEEE 802.22 Spectrum Manager (SM).

This paper describes optical access network technologies that support future radio access networks. Packet-based BBU is expected to accommodate multiple services and PON with low-latency scheme is a promising candidate to for MFH transmission in future radio access networks.

Recently, the fast evolution of wireless technologies has enabled the development of multi-interface mobile terminal which can support more radio interfaces. In this context, the users can enjoy various mobile applications by using different access networks at anytime and anywhere and with the best quality of service (QoS). However, the selection of the most appropriate access interface for the end-users is one of the most issue in this heterogeneous wireless networks. In order to deal with this task, we propose improved policy for network selection decision which combines the enhanced-TOPSIS method and the utility function. Firstly, the enhanced-TOPSIS method, is introduced to quantify the performance for each radio access network. Then, the utility function is applied to measure the degree of satisfaction when the mobile terminal moves out of range of the wireless access point. The simulation results illustrate that our optimal policy can achieve a significant improvement concerning the reversal phenomenon, the ping-pong effect and the number of handoffs failures.

The number of communication networks' users using bandwidth-intensive application, such as video-streaming, video-conferencing, and multi-player gaming is on the rise. To handle a large number of such users, the bandwidth of cellular networks is becoming scarce. Nowadays, most user equipments (mobile phones, tablets, net-books, etc) support multiple radio access technologies (RATs), such as long-term evolution (LTE) and WiFi. Therefore, cellular network service providers are using multiple RATs to increase their networks' capacity, and such networks are called heterogeneous networks (HetNets). Usually, in a HetNet, a user equipment (UE) selects an access network based on the network service provider's priority list. An access network selection based on the priority list may not result in an efficient utilization of the available networks' resources. Therefore, in this paper we focus on continuously monitoring the state of a HetNet using received signal strength indicator (RSSI), throughput, and delay metrics. Based on these metrics, we present access network selection and switching algorithms. Our experimental results demonstrate that, if the aggregate data generation rate of UEs in a HetNet is higher than the achievable data rate on LTE uplink, RSSI is the best metric for the access network selection and switching. Otherwise, the metrics demonstrate similar performance.

In an Inter-WLAN-System, when an UE needs to hand over to an untrusted network, e.g., M, from its serving network, e.g., N, how to choose M and the best base station under M currently is a problem yet to be completely solved, no matter whether M and N belong to the same alliance group or not and no matter whether M and N are homogeneous or heterogeneous networks. In fact, 3GPP recommended ANDSF to solve this problem when N is a 3GPP network and M is a non-3GPP system or vice versa, i.e., when they are heterogeneous networks. Also, when selecting M, current approach neither considers the entire characteristics of mobile users, nor having significant discovery and selection policies to show the states of M, thus often leading UE to select an inappropriate M and/or a base station B in M. It results in the fact that after handover, UE may sometimes find that Radio Signal Strength Indicator (RSSI) of B is not strong, and even UE cannot connect itself to B since B's load is high. That means when M and N do not belong to the same alliance, the problem will be more serious. It also means that if we want to solve the mentioned problem in such an environment, the functions of ANDSF need to be enhanced. Therefore, in this paper, we first design an enhanced ANDSF, named E-ANDSF, which increases ANDSF with a Multiple Parameters Decision Making (MPDM) ranking scheme based on Proxy Mobile IPv6 (PMIPv6) protocol to provide PMAG in N with sufficient information, with which UE can hand over to an appropriate base station. We also propose an improved IP-based handover approach, called IP-based Handover Scheme assisted by E-ANDSF Function (IHEADs for short), which assists UE to hand over to an appropriate target base station by accessing the information provided by E-ANDSF.

To study wireless network, a network simulator always is an important tool for researchers to evaluate their theories. If a selected simulator inherently has poor architecture, the maintenance, will become more difficult in the future. To increase the flexibility of a simulator's architecture, the use of design patterns as the norms of system architecture design is suggested in this paper. We propose a network simulator architecture, named as CCGns, which is a discrete-event virtual network simulator and follows the IEEE 802.16-2009 standard. The main contribution of CCGns is to propose five aspects: a scalable MAC messages management and processing architecture, an applicable for multi-hop relay network architecture, a two-stage minimum variance bandwidth allocation algorithm, a comparable compound factors-based common scheduler operating interface architecture, and an exchangeable frame structure architecture for WiMAX and LTE. In the aspect of expanding module function, we show the simulation results of using uniform, random, or round-robin scheduling to allocate bandwidth resource. We try to replace the WiMAX frame structure with LTE frame structure, and demonstrate the system performance of the relay network architecture for WiMAX and LTE protocol. We hope this study will benefit researchers who need to implement their network simulators.

In order to realise 5G communication, massive regulations and standards are proposed. Among all the approaches, Heterogeneous Networks (HetNets) have become one necessary and popular solution since it can reuse the existing infrastructure. The focus of cellular network has changed since the last generation from operator centric to user centric services. In HetNets, wisely utilising all the available radio access interfaces and distributing the traffic flow properly can significantly increase Quality of user Experience (QoE) and motivate more data consuming. For purpose of achieving QoE supported HetNets/5G, intelligent network selection schemes in HetNets based approach is demanded. In order to distribute diverse traffic into suitable network interfaces, Access Network Discovery and Selection Function (ANDSF) is proposed by 3GPP, which can distribute every data packet to a preferred network interface according to several observed features from that packet. However, static policies in ANDSF can neither understand the context nor adapt to real time changes. In this paper, we proposed a serverclient based Context aware Traffic identification Kit (TriCK) to dynamically identify traffic, which can be used to extend the functionalities of 3GPP ANDSF. This kit can classify traffic data not only based on its characteristics, but also the real time network conditions and the context.

Today, mobile network operators have a variety of options for the means of providing more coverage, capacity, and services to their subscribers. Alongside the advancement of wireless standards to provide higher spectral efficiency, vendors have released a wide range of radio access nodes for network densification.

Mobile devices are increasingly presented with multiple connectivity options, including WiFi hotspots, micro-/macro-cells or even other devices in device-to-device (D2D) communications. By and large, connectivity management for mobile devices has primarily focused on contention, congestion and wireless medium conditions. In this paper, we assess the role of information-centrism in mobile device connectivity management. Motivated by the increasing availability of content and services in in-network caches and micro-data centres, we design an access network selection scheme that takes into account information availability within each connectivity option. Our simulations show that information-awareness results in a significant increase of cache hit ratios by up to 115% in certain scenarios.

The Long Term Evolution-Advanced (LTE-A) is a promising technology to support vehicular communication. In an LTE-A multi-tier network, macro cell networks can overlay multiple small cell networks of different sizes, such as femto and pico, to improve the overall capacity and quality of service. However, multi-tier networks can result in frequent unwanted handover activities, unnecessary scanning of small cell networks and reduced throughput leading to a degradation of the overall network performance. Here we propose a mobility-aware network selection method in a multi-tier network where an LTE-A user equipment (UE) can self-select a suitable target network for handover depending on the direction of its mobility, its dwelling time within the coverage area of a network and the received signal strength from the base station or Evolved Node B (eNB) of a network. Simulation results show that our method can improve the network packet delivery ratio by 20% and reduce the end-to-end delay by 14%.

The functional architecture of the EPS (Evolved Packet System) network is described, when the mobile attaches to its home network.

Heterogeneous multi-radio networks are emerging network architectures that comprise hierarchical deployments of increasingly smaller cells. In these deployments, each user device may employ multiple radio access technologies to communicate with network infrastructure. With the growing numbers of such multi-radio consumer devices, mobile network operators seek to leverage spectrum across diverse radio technologies, thus boosting capacity and enhancing quality of service. In this article, we review major challenges in delivering uniform connectivity and service experience to converged multiradio heterogeneous deployments. We envision that multiple radios and associated device/infrastructure intelligence for their efficient use will become a fundamental characteristic of future 5G technologies, where the distributed unlicensed-band network (e.g., WiFi) may take advantage of the centralized control function residing in the cellular network (e.g., 3GPP LTE). Illustrating several available architectural choices for integrating WiFi and LTE networks, we specifically focus on interworking within the radio access network and detail feasible options for intelligent access network selection. Both network- and user-centric approaches are considered, wherein the control rests with the network or the user. In particular, our system-level simulation results indicate that load-aware usercentric schemes, which augment SNR measurements with additional information about network loading, could improve the performance of conventional WiFi-preferred solutions based on minimum SNR threshold. Comparison with more advanced network-controlled schemes has also been completed to confirm attractive practical benefits of distributed user-centric algorithms. Building on extensive system-wide simulation data, we also propose novel analytical space-time methodology for assisted network selection capturing user traffic dynamics together with spatial randomness of multi-radio heterogeneous networks.

Several key enabling techniques are introduced for next-generation wireless communication systems. Small-cell and cloud-RAN systems have been considered as promising solutions to meet the capacity demand of the future wireless access networks. In addition, utilization of high radio frequency (e.g., millimeter-wave band) is another dimension to expand the spectrum to enhance the throughput. From the network perspective, a high capacity, low latency, and reliable backhaul/fronthaul network is important to support the advanced wireless access techniques. Therefore, microwave-photonics techniques can play an important role in the integrated optical-wireless access systems for next-generation wireless communications. In this paper, we first review several key features and enabling techniques for next-generation 5G wireless communications. Then, we introduce a multiservice small-cell wireless access architecture based on microwave-photonics technologies (cloud radio-over-fiber networks). By combining small-cell cloud-RAN concept with multiband delivery capability in an integrated optical-wireless access system, the proposed architecture can realize high-speed multiservice data transmission in a simplified and flexible way. An in-building cloud radio-over-fiber testbed was demonstrated with real-time WiMAX traffic. Two different approaches of delivering conventional services and future-proof high-data-rate millimeter-wave services in a converged platform are also analyzed and summarized.

Next generation wireless networks consist of heterogeneous access technologies. In order to provide global ubiquitous communication, it is required to provide a framework in which user can move across multiple access interfaces while maintaining its ongoing communication at perceived quality of service. Given the scenario of multiple access networks, it is further required to select the optimum network out of multiple candidate networks to meet the requirements of the ongoing session. The selection of optimum network in such heterogeneous environment is generally based on network conditions and user preference. In this paper, we propose an algorithm for network selection based on averaged received signal strength, outage probability and distance. The proposed algorithm comprises of two stages. Assuming that network conditions are dominant in network selection, in first stage, overlapping region is identified through distance estimation. Network selection algorithm based on averaged received signal strength plus outage is invoked in second stage to select the optimum network. Numerical results are obtained through a simulation model of two disparate networks – GSM and UMTS. It has been shown that the proposed algorithm offers 68% improved performance in terms of network selection rate.

Continuous development and evolution of mobile communications toward end user expectations has led to heterogeneous mobile networks in the most general sense of the word. The mixture of core network infrastructures and radio access technologies, due to the arrival of new technologies while older ones are still used and not fully exploited, brings mobile operators to a complex business environment. Such a situation threatens future profit margins since the cost of running mobile networks rises with greater pace than total profit. A significant share in the total costs of running a mobile network belongs to energy consumption. Decreasing energy costs by designing hardware with low-energy consumption characteristics and site collocation is already under way, but additional sparing could be achieved through soft solutions or adaptive networks. To reduce operational costs, the crucial role will be played by the self-organizing network paradigm, featured by network management systems and operations/business support systems. In this paper, the authors provide an overview of adaptive and resilient concepts appropriate for improving the energy efficiency of mobile access networks. More precisely, they present the most promising self-organizing network solutions in the radio access and backhaul part of mobile networks, the implementation of which can bring a synergetic effect in terms of significant energy savings.

This article introduces the basic concepts of optical access network, technical characteristics, the next type of optical access network applications, business support capabilities, configuration, structure, selection of future development trends of the optical access network.

The bandwidth demand of telecommunication network is growing rapidly due to the increasing number of technology-intelligent end-users. The emerging optical and wireless access networks are continuously competing with each other to provide these requirements for the end-users. The optical access networks provide huge data rate and long-distance link, but it is less ubiquitous. The wireless access networks provide flexible and ubiquitous communication with a low deployment cost. However, its deployment scalability is limited by the spectrum and range limitations. The hybrid wireless optical broadband access network (WOBAN) is a powerful combination of optical backhaul and wireless front-end to contribute to a good scalability, cost effective and flexible communication system. This paper reviews the key enabling access technologies and progress advancements of these networks. The emerging optical and wireless access technologies are also presented and compared.

This article studies the cognitive access in convergence communications. Convergence communications provide upper-layer applications with uniform communication service, converging different lower-layer networks into a uniform access pattern such as all-IP communications. As an import access in convergence communications, the cognitive access provides users with a flexible and dynamic access to networks. In this article, we do not only take into account the spectrum usage of convergence communication networks, but also consider theirs energy efficiency. An energy-efficient access algorithm is proposed to improve network performance and efficiency. Different from the existing cognitive access, we regard energy efficiency as the optimal objective to turn the energy-efficient cognitive access into an optimal problem. The collision avoidance and sleeping mechanisms are used to reduce energy consumption and raise network throughput. The utility function is proposed to maximize networks’ energy efficiency and then achieve the energy-efficient cognitive access. Simulation results show that the proposed approach is effective and feasible, which can significantly improve networks’ energy efficiency.

The continuing growth in video content exchanged by mobile users creates challenges for the network service providers in terms of supporting seamless multimedia delivery at high quality levels, especially given the existing wireless network resources. A solution that deals with this mobile broadband data growth is to make use of multiple networks supported by diverse radio access technologies. This multiaccess solution requires innovative network selection mechanisms to keep the mobile users always best connected anywhere and anytime. Additionally, there is a need to develop energy efficient techniques in order to reduce power consumption in next-generation wireless networks, while meeting user quality expectations. In this context, this paper proposes an enhanced power-friendly access network selection solution (E-PoFANS) for multimedia delivery over heterogeneous wireless networks. E-PoFANS enables the battery of the mobile device to last longer, while performing multimedia content delivery, and maintains an acceptable user perceived quality by selecting the network that offers the best energy-quality tradeoff. Based on real test-bed measurements, the proposed solution is modeled and validated through simulations. The results show how by using E-PoFANS, the users achieve up to 30% more energy savings with insignificant degradation in quality, in comparison with another state-of-the-art energy efficient network selection solution.

The management process between different wireless technologies for mobile devices is very important to complete the handover operations. The handover operation needs to determine the delay and packet loss in order to be the quality of service within a certain level. Selecting the best available network at the appropriate time is very significant in the direction of realizing ubiquitous networks. In this paper a network selection approach named enhanced access router discovery (EARD) is proposed. The approach is developed to work in a heterogeneous environment including of WiMAX and WLAN networks. The EARD method utilizes the prioritized rating for multiple criteria (PRMC) proposed for selecting the target network. The proposed approach is evaluated with respect to various conditions with different traffic types. The simulation results show that our proposed approach outperform the traditional network selection methods is selecting the most appropriate network.

The paper proposes a new network selection procedure using access networks consent. The proposed mechanism supports WLAN, WIMAX and 3G networks. Using mobility prediction model coupled with GIS information system the access networks at future location of mobile terminal. Using pre handover mechanisms with EAP HO NS and AAA extensions proposed in this paper the home access networks negotiate with visiting access networks and networks entities to allocate and reserve resources for accommodating mobile terminals enabling the solution proposed is efficient. Using these mechanisms the mobile terminal mobility can be handled efficiently in any access networks. The proposed solution addresses all the issues that are raised by network selection procedures. As a part of our future work we are coupling this mechanism with security, mobility and handover management procedures to control and provide seamless handover during roaming.

Today's mobile devices such as smart phones are equipped with multiple wireless access technologies, so multi-radio operation is becoming the norm. These devices frequently face vertical handover scenarios such as exiting Wi-Fi hotspot towards cellular network coverage. Unfortunately, the vertical handover execution is still done in a very primitive way even with middleware support, and the reality is that any active service at the time of handover is aborted or at least severely disrupted when it happens. In this paper, we explore how the transport layer can independently overcome the disruption caused by the vertical handover and obtain service continuity with or without underlying vertical mobility support infrastructures such as Media Independent Handover (MIH) or Access Network Discovery and Selection Function (ANDSF). In particular, we focus on the case of User Datagram Protocol (UDP), and explore how to evolve it for vertical handover. In particular, we show that UDP can be enriched with options while keeping application transparency and enabling incremental deployment as is the case for Transmission Control Protocol (TCP). We implement the proof-of-concept prototype and demonstrate that it performs well under dynamic Cellular-WiFi vertical handover settings with off-the-shelf smart phones operating across commercial 3G cellular carriers and Internet Service Provider (ISP) networks. We also consider the ways to utilize the evolved UDP for other applications, as the addition of carrying options or in-band signaling capability opens a whole new horizon for the usability of UDP.

To provide secure and efficient access control methods in cloud computing environments, many system models have been proposed that employ attribute-based encryption and proxy re-encryption schemes. Most of these access control schemes are based on the user’s authentication information and access privileges. However, when users request access privileges through non-secure environments such as mobile devices and wireless networks, we need to be able to restrict access requests, depending on the user’s context-aware information. To achieve this, in this paper we propose an access restriction scheme for access to cloud data that is based on context-aware information.1

In the 4G wireless environment, one of the important issues is to discover and select an access network suited for users. In this thesis, we propose a new network selection mechanism using group decision making and evaluate the effect of network selection schemes for vertical handover in heterogeneous wireless networks. We consider the group of users with similar QoS requirements search for the available access network simultaneously and a service area consist of multiple access networks with various characteristics. We divide the access networks with similar characteristics split into a group. Between each group, the one group is selected and within that group, the best access networks will be assigned according to priority order by network selection algorithm. We evaluate and compare the performance of three representative MADM schemes: GRA, SAW and TOPSIS. The MATLAB simulation results indicate the proposed algorithm can make a more effective choice according to the networks` characteristics and user`s preference.