Abstract: Cognitive communication model perform the investigation and surveillance of spectrum in cognitive radio networks abetment in advertent primary users (PUs) and in turn help in allocation of transmission space for secondary users (SUs). In effective performance of regulation of wireless channel handover strategy in cognitive computing systems, new computing models are desired in operating set of tasks to process business model, and interact naturally with humans or machine rather being programmed. Cognitive wireless network are trained via artificial intelligence (AI) and machine learning (ML) algorithms for dynamic processing of spectrum handovers. They assist human experts in making enhanced decisions by penetrating into the complexity of the handovers. This paper focuses on learning and reasoning features of cognitive radio (CR) by analyzing primary user (PU) and secondary user (SU) data communication using home location register (HLR) and visitor location register (VLR) database respectively. The SpecPSO is proposed for optimizing handovers using supervised machine learning technique for performing dynamic handover by adapting to the environment and make smart decisions compared to the traditional cooperative spectrum sensing (CSS) techniques.

Abstract: Supporting smooth movement of mobile clients is important when offloading services on an edge computing platform. Interruption-free client mobility demands seamless migration of the offloading service to nearby edge servers. However, fast migration of offloading services across edge servers in a WAN environment poses significant challenges to the handoff service design. In this paper, we present a novel service handoff system which seamlessly migrates offloading services to the nearest edge server, while the mobile client is moving. Service handoff is achieved via container migration. We identify an important performance problem during Docker container migration. Based on our systematic study of container layer management and image stacking, we propose a migration method which leverages the layered storage system to reduce file system synchronization overhead, without dependence on the distributed file system. We implement a prototype system and conduct experiments using real world product applications. Evaluation results reveal that compared to state-of-the-art service handoff systems designed for edge computing platforms, our system reduces the total duration of service handoff time by 80%(56%) with network bandwidth 5Mbps(20Mbps).

Abstract: Cognitive radio systems necessitate the incorporation of cooperative spectrum sensing among cognitive users to increase the reliability of detection. We have found that cooperative spectrum sensing...

Abstract: This paper proposes a telecom big data based user offloading self-optimisation TBDUOS scheme. Its aim is to assist telecom operators to effectively balancing the load distribution with achieving good service performance and customer management in heterogeneous relay cellular systems. To achieve these objectives, in the cell-level offloaded traffic analysis stage, the optimal offloaded traffic is calculated to minimise the total blocking probability. In the user-level offloading stage, the user portrait is drawn and the K-MEANS algorithm is employed to manage the users clustering in the heavily loaded cell, and finally shifting users to assistant cells. Simulation results show the TBDUOS scheme can effectively reduce the handover failure and call dropping of specific users, especially voice/stream users, high consumption users, high level users. The TBDUOS scheme can also reduce the blocking probability.

Abstract: Long Term Evolution, the fourth generation of mobile communication technology, has been commercially deployed for about five years. Even though it is continuously updated through new releases, and with LTE Advanced Pro Release 13 being the latest one, the development of the fifth generation has been initiated. In this article, we measure how current LTE network implementations perform in comparison with the initial LTE requirements. The target is to identify certain key performance indicators that have suboptimal implementations and therefore lend themselves to careful consideration when designing and standardizing next generation wireless technology. Specifically, we analyze user and control plane latency, handover execution time, and coverage, which are critical parameters for connected mobility use cases such as road vehicle safety and efficiency. We study the latency, handover execution time, and coverage of four operational LTE networks based on 19,000 km of drive tests covering a mixture of rural, suburban, and urban environments. The measurements have been collected using commercial radio network scanners and measurement smartphones. Even though LTE has low air interface delays, the measurements reveal that core network delays compromise the overall round-trip time design requirement. LTE's breakbefore- make handover implementation causes a data interruption at each handover of 40 ms at the median level. While this is in compliance with the LTE requirements, and lower values are certainly possible, it is also clear that break-before-make will not be sufficient for connected mobility use cases such as road vehicle safety. Furthermore, the measurements reveal that LTE can provide coverage for 99 percent of the outdoor and road users, but the LTE-M or NarrowBand-IoT upgrades, as of LTE Release 13, are required in combination with other measures to allow for additional penetration losses, such as those experienced in underground parking lots. Based on the observed discrepancies between measured and standardized LTE performance, in terms of latency, handover execution time, and coverage, we conclude the article with a discussion of techniques that need careful consideration for connected mobility in fifth generation mobile communication technology.

Abstract: Ultra-densification is a key approach aimed at satisfying high data traffic in next-generation 5G networks. However, the high number of small cell eNB deployments in such ultra-dense networks (UDNs) may result in unnecessary, frequent, and back-and-forth handovers, with additional problems related to increased delay and total failure of the handoff process. Additionally, due to the separation of control and data signaling in 5G technology, the handover operation must be executed in both tiers. In this article, we propose an SDN-based mobility and available resource estimation strategy to solve the handover delay problem. Here, we estimate the neighbor eNB transition probabilities of the mobile node and their available resource probabilities by using a Markov chain formulation. This allows a mathematically elegant framework to select the optimal eNBs and then assign these to mobile nodes virtually, with all connections completed through the use of OpenFlow tables. Finally, we compare the conventional LTE and our proposed handover strategies by analyzing the observed delays according to the densification ratio parameter. Also, we analyze the handover failure ratios of both strategies according to the user number. Results reveal that the proposed strategy reduces the handover delay and failures by 52 and 21 percent compared to the conventional approach.

Abstract: While network densification is considered an important solution to cater the ever-increasing capacity demand, its effect on the handover (HO) rate is overlooked. In dense 5G networks, HO delays may neutralize or even negate the gains offered by network densification. Hence, user mobility imposes a nontrivial challenge to harvest capacity gains via network densification. In this paper, we propose a velocity-aware HO management scheme for two-tier downlink cellular network to mitigate the HO effect on the foreseen densification throughput gains. The proposed HO scheme sacrifices the best base station (BS) connectivity, by skipping HO to some BSs along the user trajectory, to maintain longer connection durations and reduce HO rates. Furthermore, the proposed scheme enables cooperative BS service and strongest interference cancellation to compensate for skipping the best connectivity. To this end, we consider different HO skipping scenarios and develop a velocity-aware mathematical model, via stochastic geometry, to quantify the performance of the proposed HO schemes in terms of the coverage probability and user throughput. The results highlight the HO rate problem in dense cellular environments and show the importance of the proposed HO schemes. Finally, the value of BS cooperation along with handover skipping is quantified for different user mobility profiles.

Abstract: Equipped with easy-to-access micro computation access points, the fog computing architecture provides low-latency and ubiquitously available computation offloading services to many simple and cheap Internet of Things devices with limited computing and energy resources. One obstacle, however, is how to seamlessly hand over mobile IoT devices among different computation access points when computation offloading is in action so that the offloading service is not interrupted -- especially for time-sensitive applications. In this article, we propose Follow Me Fog (FMF), a framework supporting a new seamless handover timing scheme among different computation access points. Intrinsically, FMF supports a job pre-migration mechanism, which pre-migrates computation jobs when the handover is expected to happen. Such expectations can be indicated by constantly monitoring received signal strengths. Then we present the design and a prototype implementation of FMF. Our evaluation results demonstrate that FMF can achieve a substantial latency reduction (36.5 percent in our experiment). In conclusion, the FMF design clears a core obstacle, allowing fog computing to provide interruption-resistant services to mobile IoT devices.

Abstract: LTE-based satellite systems in LEO constellations are a promising solution for extending broadband coverage to areas not connected to a terrestrial infrastructure. However, the large delays and Doppler shifts over the satellite channel pose severe technical challenges to a traditional LTE system. In this paper, two architectures are proposed for a LEO mega-constellation realizing a satellite-enabled LTE system, in which the on-ground LTE entity is either an eNB (Sat-eNB) or a Relay Node (Sat-RN). Focusing on the latter, the impact of large delays and Doppler shifts on LTE PHY/MAC procedures is discussed and assessed. It will be shown that, while carrier spacings, Random Access, and RN attach procedures do not pose specific issues, HARQ requires substantial modifications. Moreover, advanced handover procedures will be also required due to the satellites' movement.

Abstract: The communication in the Smart Home Internet of Things (SH-IoT) comprising various electronic devices and sensors is very sensitive and crucial In addition, the key requirements of the SH-IoT include channel security, handover support, mobility management, and consistent data rates Proxy mobile IPv6 (PMIPv6) is considered as one of the core solutions to handle extreme mobility; however, the default PMIPv6 cannot ensure performance enhancement in SH-IoT scenarios, ie, Route Optimization (RO) The existing security protocols for PMIPv6 cannot support secure RO for smart home IoT services, where mobile nodes (MNs) communicate with home IoT devices not belonging to their domain Motivated by this, a secure protocol is proposed, which uses trust between PMIPv6 domain and smart home to ensure security as well as performance over the path between MNs and home IoT devices The proposed protocol includes steps for secure RO and handover management, where mutual authentication, key exchange, perfect forward secrecy, and privacy are supported The correctness of the proposed protocol is formally analyzed using BAN-logic and Automated Validation of Internet Security Protocols and Applications (AVISPA) Furthermore, network simulations are conducted to evaluate the performance efficiency of the proposed protocol The results show that the proposed approach is capable of providing secure transmission by resolving the RO problem in PMIPv6 along with the reduction in handover latency, end to end delay and packet loss, and enhancement in throughput and transmission rate even during the handover phase

Abstract: The evolving cellular network with centric-deployed Cloud Centers has greatly improved the mobile user experience. However, the advent of vehicular networks with a wide variety of new services and devices changes the existing cellular network landscape, and the cellular-based vehicular networks are confronted with serious challenge in terms of latency reduction and flexible service delivery. In this paper, we propose to deploy the specific server, called Mobile-Edge Computing (MEC) server, within the Radio Access Network, and allow them to connect with a set of base stations alongside roads, so as to provide flexible vehicle-related service and efficiently control the radio network. Then, the vision of MEC- assisted slicing network and a traffic scheduling policy are presented to promote network customization. As an instance of the MEC-based tailored network service, a time-predicted handover mechanism for vehicles is further developed by leveraging available road information and the enhanced capacity of the MEC server to satisfy the demand for high mobility and reliability.

Abstract: With the increase of new devices and applications, the past decade has witnessed exponential growth of traffic volume in communication networks. This triggers much effort for designing NWNs in both academia and industry. To gain natural evolution and meet emerging requirements, it is widely agreed that NWNs shall be multi-tier with overlay coverage and small cell deployment. However, dense deployment of small cells introduces numerous challenges, including inconsistent interfaces, frequent handovers, and extensive backhauling. By decomposing the control plane and data plane, SDN offers a new direction to address the above challenges. In this article, by introducing SDNC, we propose an intelligent wireless network architecture for NWNs. In our architecture, virtual RATs design using interface sets is brought up to support diverse services. Along with our earlier handover approach, low handover latency between heterogeneous networks is achieved. Furthermore, we present SH mechanisms targeted at different failure cases in backhaul connections. With programmability provided by SDN, the aforementioned functions can be deployed as modules in the SDNC. Experimental results validate the efficiency of our proposal.

Abstract: The fifth-generation (5G) networks are expected to be able to satisfy users' different quality-of-service (QoS) requirements. Network slicing is a promising technology for 5G networks to provide services tailored for users' specific QoS demands. Driven by the increased massive wireless data traffic from different application scenarios, efficient resource allocation schemes should be exploited to improve the flexibility of network resource allocation and capacity of 5G networks based on network slicing. Due to the diversity of 5G application scenarios, new mobility management schemes are greatly needed to guarantee seamless handover in network slicing based 5G systems. In this article, we introduce a logical architecture for network slicing based 5G systems, and present a scheme for managing mobility between different access networks, as well as a joint power and subchannel allocation scheme in spectrum-sharing two-tier systems based on network slicing, where both the co-tier interference and cross-tier interference are taken into account. Simulation results demonstrate that the proposed resource allocation scheme can flexibly allocate network resources between different slices in 5G systems. Finally, several open issues and challenges in network slicing based 5G networks are discussed, including network reconstruction, network slicing management and cooperation with other 5G technologies.

Abstract: Extending cloud infrastructure to the Network Edge represents a breakthrough to support delay-sensitive applications in next 5G cellular systems. In this context, to enable ultrashort response times, fast relocation of service instances between edge nodes is required to cope with user mobility. To face this issue, proactive service replication is considered a promising strategy to reduce the overall migration time and to guarantee the desired Quality of Experience (QoE). On the other hand, the provisioning of replicas over multiple edge nodes increases the resource consumption of constrained edge nodes and the relevant deployment cost. Given the two conflicting objectives, in this paper we investigate different optimization models for proactive service migration at the Network Edge, which can exploit prediction of user mobility patterns. In particular, we define two Integer Linear Problem optimization schemes, which aim at respectively minimizing the QoE degradation due to service migration, and the cost of replicas' deployment. Performance evaluation shows the effectiveness of our proposed solutions.

Abstract: The handover process is one of the most critical functions in a cellular network and is in charge of maintaining seamless connectivity of user equipments across multiple cells. The handover process is driven by signal measurements from the neighboring base stations (BSs), and it is adversely affected by the time and frequency selectivity of the radio propagation channel. In this paper, we introduce a new model for analyzing handover performance in heterogeneous networks (HetNets) as a function of vehicular user velocity, cell size, and mobility management parameters. In order to investigate the impact of shadowing and fading on handover performance, we extract relevant statistics obtained from a Third-Generation Partnership Project (3GPP)-compliant HetNet simulator, and subsequently, we integrate these statistics into our analytical model to analyze both handover failure and ping-pong probabilities under fluctuating channel conditions. Computer simulations validate the analytical findings, which show that fading can significantly degrade the handover performance in HetNets with vehicular users.

Abstract: Compared to traditional networking, SDN has better controllability and visibility for network components, which enable better management by using the common controller. In this article, the standard architecture of SDN is enhanced to utilize UAVs as on-demand forwarding switches. The proposed approach can achieve efficient management and fast handovers by decreasing the handover latency, E2E delay, and signaling overheads. The illustrated scenarios will help in understanding the impact of existing handover approaches in the next generation wireless networks, especially the upcoming 5G, which includes small cells, UAVs, UEs, and so on. The simulation study shows that scenarios with both UAVs and small cells perform better than scenarios with only small cells. The results in this article show that the proposed SDNbased handover scenarios perform better than the existing 4G-LTE handover for UAVs.

Abstract: Denser deployments of heterogeneous networks (HetNets) lead to more frequent handovers, which results in a decline of user experience as well as heavy signaling overheads to the network. Therefore, the study on handover is of great importance especially in dense HetNets. In this paper, we focus on the analysis of cross-tier handover from the macro cell tier to the small cell tier, which shows the highest handover failure rate in current standards and industry studies. Using the stochastic geometry, we propose an analytical model for the cross-tier handover processes in the HetNet. Based on the derived analytical model, the closed-form expressions for the key handover performance metrics, including the handover rate, handover failure rate, and ping-pong rate, are deduced as functions of the base station density, time to trigger and user mobility. Simulation results verify the accuracy of the proposed analytical model and closed-form theoretical analyses, which provide guidance for the deployments of HetNets and corresponding handover strategies.

Abstract: A high-speed railway system equipped with moving relay stations placed on the middle of the ceiling of each train wagon is investigated. The users inside the train are served in two hops via orthogonal frequency-division multiple-access (OFDMA) technology. In this paper, we first focus on minimizing the total downlink power consumption of the base station (BS) and the moving relays while respecting specific quality-of-service (QoS) constraints. We first derive the optimal resource-allocation solution, in terms of OFDMA subcarriers and power allocation, using the dual decomposition method. Then, we propose an efficient algorithm based on the Hungarian method to find a suboptimal but low-complexity solution. Moreover, we propose an OFDMA planning solution for high-speed trains by finding the maximal inter-BS distance, given the required user data rates to perform seamless handover. Our simulation results illustrate the performance of the proposed resource-allocation schemes in the case of Third-Generation Partnership Project (3GPP) Long-Term Evolution Advanced (LTE-A) and compare them with previously developed algorithms, as well as with the direct transmission scenario. Our results also highlight the significant planning gain obtained, owing to the use of multiple relays instead of the conventional single-relay scenario.

Abstract: This paper proposes a new SDN(Software Defined Network) based handover scheme to satisfy the delay requirement of less than 1ms, which is the main requirement of 5G network. The SDN controller collects mobility and BS(Base Station) status information from UE(User Equipment) and uses the processed data to select next cell. In this case, LP(Linear Programming) problem solving technique is applied to reduce calculation amount in the cell selection. In addition, a channel would be allocated in advance to selected cell, thereby reducing time required for handover and providing fast and seamless service. Simulation results show that the proposed method find cells with strong signal strength, long sojourn time and low cell load according to the movement direction.

Abstract: Recently, the concept of 5G vehicular smallcell networking (V-SCN) has been proposed to meet the growing demand of mobile data services in vehicular communications. However, it is a great challenge to explore spectrum and energy efficiency due to the fast vehicle mobility and varying communication environment. In this article, we focus on critical issues, such as interference management and handover, when employing 5G V-SCNs. In order to solve these issues, the network architecture embedded with NOMA is deigned. Furthermore, we propose a hierarchical power control solution to perform the joint optimization of cell association and power control to improve the spectrum and energy efficiency in NOMA-enabled 5G V-SCNs. Numerical comparison results provide some guidelines for developing NOMA-enabled 5G V-SCNs in an economical and highly energy-efficient manner.

Abstract: Arbitrary flow arrival and satellite communication hot spot cause uneven traffic distribution, which breaks load balancing even results in congestion in partial nodes. In this paper, we propose a State-Aware and Load-Balanced (SALB) routing model for LEO (low earth orbit) satellite networks. We firstly propose a mechanism to quantitatively estimate link states and dynamically adjust the weight of queuing delay. SALB divides the occupancy rate of each queue into n levels and each level corresponds to a link state. Then, we develop the SALB model that considers various situations including load change, and link and node failure and recovery. Routing tables are reset up at the beginning of each handover and are dynamically updated through an efficient shortest path tree algorithm between two successive handovers, which significantly lower routing overhead. We evaluate our SALB model through a NS2-based system. The results demonstrate that our SALB outperforms related proposals in terms of system throughput, end-to-end delay, and packet drop rate.

Abstract: The subject matter of the article is the processes of load distribution in mobile communication networks. The object of research is the handover. The goal is to develop a method for redistributing the load between neighboring areas for mobile nodes. The considered base stations are supposed to have the signal-to-noise ratios that are equal or close. The methods t hat are used: methods of system analysis, methods of digital signal processing. The following results are obtained. The method that allows mobile nodes, whose signal-to-noise ratios are equal or close, to switch to a less loaded base station. This method allows the base station to launch the handover process enabling more even distribution of the load from mobile nodes among neighboring base stations in wireless and mobile networks. In the suggested modification of the method, the function assessing the bandwidth of the uplink channel is added to the base stations, as well a threshold value for using its bandwidth. Thus, when the current value of bandwidth reaches the threshold, the base station starts sending out a message to all mobile nodes and verifies free neighboring areas for switching over mobile nodes. If there are adjacent areas with a lower load, the base station notifies all potential candidates about the necessity of their switching over. The handover process is launched when the available bandwidth of the base station decreases below a certain threshold. Therefore, it is possible to optimize the operation of the WiMAX network with respect to the criterion of the total bandwidth capacity of the base stations. Besides, the results of the comparative analysis of the handover process in networks based on the WiMAX technology that are obtained using the OpNet simulation environment are presented. Conclusions. The suggested approach can be used to improve the basic software of mobile communication networks. When moving a node from one area to another one in access servers, the node allocation tables are adjusted according to the developed method. Also, the suggested method enables improving and balancing the load of the base stations of mobile communication networks. The obtained results enables maintaining the required level of service quality in mobile communication networks.

Abstract: The industry standard 3GPP mobility solutions are analyzed through the lens of bandit learning theory. In particular, it is shown that the original 3GPP handover protocol, developed primarily from a radio frequency and load balancing perspective, can be viewed as a special case of the $\epsilon$-greedy bandit algorithm, and thus its sub- optimality can be characterized via the regret analysis. Inspired by the equivalence between 3GPP handover protocols and bandit algorithms, we rigorously analyze the performance of cell range expansion in 3GPP handover enhancement, and further propose a learning-based approach to address the frequent handover (FHO) challenges in ultra-dense networks. The key component is to explicitly consider the handover cost to discourage FHOs. Rather surprisingly, we prove that the bandit-inspired scheme with handover cost can be viewed as an enhancement to the simple sticky biasing solution in 3GPP that has been developed to partially address the FHO problem, and hence lay a theoretic foundation to this industrial intuition.

Abstract: Frequent handovers (HOs) in dense small cell deployment scenarios could lead to a dramatic increase in signaling overhead. This suggests a paradigm shift toward a signaling conscious cellular architecture with intelligent mobility management. In this direction, a futuristic radio access network with a logical separation between control and data planes has been proposed in research community. It aims to overcome limitations of the conventional architecture by providing high data rate services under the umbrella of a coverage layer in a dual connection mode. This approach enables signaling efficient HO procedures since the control plane remains unchanged when the users move within the footprint of the same umbrella. Considering this configuration, we propose a core-network efficient radio resource control signaling scheme for active state HO and develop an analytical framework to evaluate its signaling load as a function of network density, user mobility, and session characteristics. In addition, we propose an intelligent HO prediction scheme with advance resource preparation in order to minimize the HO signaling latency. Numerical and simulation results show promising gains in terms of reduction in HO latency and signaling load as compared with conventional approaches.

Abstract: Recently a promising concept of hybrid networks based on light fidelity (LiFi) and wireless fidelity (WiFi) emerged. The idea is to combine ultra-small cell LiFi networks with ubiquitous coverage radio frequency (RF) communication systems. In such a hybrid network, WiFi access points (APs) serve a relatively large coverage area with limited bandwidth, and are thus susceptible to traffic overload. This issue is magnified with an increasing number of users because of the inefficient medium access control (MAC) in WiFi systems. LiFi can alleviate this issue by providing additional capacity. LiFi cells, however, have a limited coverage and this could result in significant handover overhead. A conventional load balancing (LB) method optimises the network throughput when the signal-to-noise ratio (SNR) of each user is known and fixed. Although this method delivers maximum throughput at a given time instance, it fails to consider the throughput loss due to handover, especially in an indoor scenario where users may frequently switch between APs. Taking the handover overhead into account, in this paper we propose a novel LB method that focuses on optimising the network throughput over a period of time. Simulation results show that the proposed method can increase the system throughput by up to 70% compared to existing LB methods.

Abstract: The growing deployment and advanced development of high-speed train (HST) systems, coupled with the reliance on and demand for constant Internet connectivity any time any where, have necessitated the imminent provisioning of broadband Internet services in HSTs. Train-to-ground communications mostly suffers from frequent handoffs due to the high mobility of the trains. To provision high-speed Internet services in HSTs, we propose a novel solution named Free-space OptiCs Utilization in high-Speed trains (FOCUS). Our solution takes advantage of the high optical bandwidth of free space optics (FSO) to provide high data rates. FOCUS aims to improve the trainto- ground communications system by deploying on-roof FSO transceivers. To minimize the number of handoff processes, the control unit inside the train forwards each request to go through the proper transceiver. The proposed mechanism decreases the packet loss ratio and increases network performance in high-speed train communications.

Abstract: Internet of Mobile Things (IoMT) is a new paradigm of the Internet of Things (IoT) where devices such as sensors, robots, unmanned aerial vehicles (UAV) and cars, are inherently mobile While mobility enables innovative applications and allows new services, it remains a challenging issue as it causes disconnection of nodes and intermittent connectivity, which negatively impact the network performance; namely data loss, large handover delay and application functionality failures In this paper, we propose a new energy efficient and mobility aware routing protocol named EC-MRPL based on the well-known Routing Protocol for Low power and Lossy Networks (RPL standard) Unlike RPL which is designed for low resources networks with basically static devices, the proposed protocol enables to better conserve the energy and sustain the connectivity of mobile nodes EC-MRPL integrates an enhanced mobility detection method and a novel point of attachment prediction and replacement strategy aware of the resources constraints As such, EC-MRPL overcomes and mitigates problems caused by mobility Obtained simulation results using Cooja/Contiki show that EC-MRPL outperforms both the RPL and the MRPL protocols in terms of handover delay, data loss rate, signaling cost and energy consumption