Abstract: Handover (HO) is one of the key aspects of next-generation (NG) cellular communication networks that need to be properly managed since it poses multiple threats to quality-of-service (QoS) such as the reduction in the average throughput as well as service interruptions. With the introduction of new enablers for fifth-generation (5G) networks, such as millimetre wave (mm-wave) communications, network densification, Internet of things (IoT), etc., HO management is provisioned to be more challenging as the number of base stations (BSs) per unit area, and the number of connections has been dramatically rising. Considering the stringent requirements that have been newly released in the standards of 5G networks, the level of the challenge is multiplied. To this end, intelligent HO management schemes have been proposed and tested in the literature, paving the way for tackling these challenges more efficiently and effectively. In this survey, we aim at revealing the current status of cellular networks and discussing mobility and HO management in 5G alongside the general characteristics of 5G networks. We provide an extensive tutorial on HO management in 5G networks accompanied by a discussion on machine learning (ML) applications to HO management. A novel taxonomy in terms of the source of data to be utilized in training ML algorithms is produced, where two broad categories are considered; namely, visual data and network data. The state-of-the-art on ML-aided HO management in cellular networks under each category is extensively reviewed with the most recent studies, and the challenges, as well as future research directions, are detailed.

Abstract: Mobile-edge computing (MEC) enhances the capacities and features of mobile devices by offloading computation-intensive tasks over wireless networks to edge servers. One challenge faced by the deployment of MEC in cellular networks is to support user mobility. As a result, offloaded tasks can be seamlessly migrated between base stations (BSs) without compromising the resource-utilization efficiency and link reliability. In this paper, we tackle the challenge by optimizing the policy for migration/handover between BSs by jointly managing computation-and-radio resources. The objectives are twofold: maximizing the sum offloading rate, quantifying MEC throughput, and minimizing the migration cost. The policy design is formulated as a decision-optimization problem that accounts for virtualization, I/O interference between virtual machines (VMs), and wireless multi-access. To solve the complex combinatorial problem, we develop an efficient relaxation-and-rounding based solution approach. The approach relies on an optimal iterative algorithm for solving the integer-relaxed problem and a novel integer-recovery design. The latter outperforms the traditional rounding method by exploiting the derived problem properties and applying matching theory. In addition, we also consider the design for a special case of “hotspot mitigation”, referring to alleviating an overloaded server/BS by migrating its load to the nearby idle servers/BSs. From simulation results, we observed close-to-optimal performance of the proposed migration policies under various settings. This demonstrates their efficiency in computation-and-radio resource management for joint service migration and BS handover in multi-cell MEC networks.

Abstract: Ultra-dense Heterogeneous network (HetNet) technique can significantly improve wireless link quality, spectrum efficiency and system capacity, and satisfy different requirements for coverage in hotspots, which has been viewed as one of the key technologies in fifth Generation (5G) network. Due to the existence of many different types of base stations (BSs) and the complexity of the network topology in the 5G HetNets, there are a lot of new challenges in security and mobility management aspects for this multi-tier 5G architecture including insecure access points and potential frequent handovers among several different types of base stations. In this paper, we integrate user capability and Software Defined Network (SDN) technique, and propose a capability-based privacy protection handover authentication mechanism in SDN-based 5G HetNets. Our proposed scheme can achieve the mutual authentication and key agreement between User Equipments (UEs) and BSs in 5G HetNets at the same time largely reduce the authentication handover cost. We demonstrate that our proposed scheme indeed can provide robust security protection by employing several security analysis methods including the BAN logic and the formal verification tool Scyther. In addition, the performance evaluation results show that our scheme outperforms other existing schemes.

Abstract: The Open Radio Access Network (O-RAN) introducing a particular unit known as RAN Intelligent Controllers (RICs) has been regarded as revolutionary paradigms to support multiclass wireless services required in the fifth and sixth generation (5G/6G) networks. Through unprecedentedly installing various machine learning (ML) algorithms to RICs, a RAN is able to intelligently configure resources/communications to support any vertical applications over any operating scenarios. However, to practically deploy this RAN paradigm, the O-RAN still suffers two critical issues of load balance and handover control, and therefore the very first ML algorithm for the O-RAN should effectively address these issues. In this paper, inspired by the superior performance of deep reinforcement learning (DRL) in tackling sequential decision-making tasks, we therefore develop an intelligent user access control scheme with the facilitation of deep Q-networks (DQNs). A federated DRL-based scheme is further proposed to train the parameters of multiple DQNs in the O-RAN, so as to maximize the long-term throughput and meanwhile avoid frequent user handovers with a limited amount of signaling overheads in the O-RAN. The simulation results have fully demonstrated the outstanding performance over the state-of-the-arts, to service the urgent needs in the standardization of the O-RAN.

Abstract: In this Modern era, Software Defined Network (SDN), Network Function Virtualization (NFV), and cloud computing participating of Fifth Generation (5G) network emergence. This paper presents a robust security scheme to provide fortification against major threats along with user privacy in 5G network, two additional entities are introduced. For mobile users, initial authentication is provided at access points by an inventive Highly Secured Authentication and Handover Mechanism (HS-AOHM) scheme which minimizes handover latency without loss of user privacy. Then the authorized user packets are arrived at dispatcher in which a novel Tree Based Switch Assignment (TBSA) algorithm is incorporated. TBSA mitigates the flow table overloading attack by assigning packets to underloaded switches. In controller, DDoS attack is detected with the assist of entropy analysis. Then the suspicious packets are redirected to scrubbing Virtual Network Function (sVNF) in cloud. In sVNF, suspicious packets are classified into normal packets and malicious packets by using Hybrid Fuzzy with Artificial Neural Network (HF-ANN) classifier based on packet features. Normal packets are allowed to access applications whereas malicious packets are dropped at sVNF. Extensive simulation shows security improvement in 5G network in terms of handover latency, holding time, switch failure rate, detection accuracy, and delay.

Abstract: Handover scenarios referred as the transitions between a human driver and an automated driving system are challenging because some human drivers are not adapted to the vehicle steering characteristics in a handover process and thus may exhibit deteriorative driving performances. This paper proposes a robust controller to assist human drivers in the handover scenarios. A driver–vehicle model including the driver steering input is developed to enhance the cooperation between a human driver and an automated driving controller. The driver parametric uncertainties are explicitly modeled to consider different human driving performances. Then a robust controller is designed to assist the driver considering his/her steering input and parametric uncertainties. The effectiveness of the designed controller is validated through several driver-in-the-loop tests on a driving simulator. The handover test results show that the driver steering loads and the vehicle lateral deviations can be reduced by the designed controller, thereby improving the driving safety in the handover processes.

Abstract: Integrated terrestrial-satellite networks (lTSNs) are envisioned to provide seamless broadband services through evolving terrestrial B5G/6G cellular systems and emerging mega satellite constellations. The inherent dual mobility (i.e., satellites and ubiquitous mobile users) and highly overlapped satellite footprints in such ITSNs may result in massive and frequent handovers. This increases handover delays, signaling overheads, and decision making loads, especially under existing fixed, even limited, deployments of ground mobility management functions (MMFs). Thus, a lightweight handover scheme and a mobility management architecture with dynamic MMF configurations are of great significance to guarantee service continuity and management timeliness. Specifically, this article proposes mobility management architectures with an augmented reconfigurable management plane on a higher orbit. The architectures can support flexible configurations of space-distributed MMFs for efficient mobility management together with the ground MMFs. Subsequently, to achieve rapid and unified decisions for massive handovers, we design a clustering and game-based handover decision framework including centralized and distributed decision making functions for different conditions. Based on handover procedures, simulation results validate the high performance of the proposed schemes regarding handover delays, signaling overheads, and convergence property. Notably, many academic issues are worthy of further studies under this architecture, such as higher-layer constellation design and inter-layer management structure optimization.

Abstract: Wireless communication over terahertz (THz) frequency bands is envisioned as the key enabler of many applications and services offered in 6G networks. The abundantly available bandwidth in THz frequencies can satisfy the ultra-high user throughput requirements and accommodate a massive number of connected devices. However, poor propagation characteristics, shadowing, and blockages may result in sudden outages and necessitate frequent handovers. Therefore, an inefficient handover procedure will impose severe challenges in meeting the ultra-high reliability and low latency requirements of emerging applications. In blockage driven mmWave and THz networks, a higher multi-connectivity degree and efficient handover procedures are needed to reduce the data plane interruptions and to achieve high reliability. We present an analytical model to study the impact of handover procedures and multi-connectivity degree on the latency and reliability of blockage driven wireless networks. From the network protocol design perspective, our study offers a quick and accurate way to envisage how network architecture and protocols should evolve in terms of multi-connectivity degrees and handover procedural efficiency. Our results suggest that, for THz systems, coverage range should be increased even if it comes at the cost of increased initial access and base station discovery times.

Abstract: 5G has been under standardization for over a decade and will drive the world's mobile technologies in the decades to come. One of the cornerstones of the 5G standard is its security, also for devices that move frequently between networks, such as autonomous vehicles, and must therefore be handed over from one network operator to another. We present a novel, comprehensive, formal analysis of the security of the device handover protocols specified in the 5G standard. Our analysis covers both handovers within the 5G core network, as well as fallback methods for backwards compatibility with 4G/LTE. We identify four main handover protocols and formally model them in the security protocol verification tool Tamarin. Using these models, we determine for each protocol the minimal set of security assumptions required for its intended security goals to be met. Understanding these requirements is essential when designing devices and other protocols that depend on the reliability and security of network handovers.

Abstract: 5G mobile networks provide additional benefits in terms of lower latency, higher data rates, and more coverage, in comparison to 4G networks, and they are also coming close to standardization. For example, 5G has a new level of data transfer and processing speed that assures users are not disconnected when they move from one cell to another; thus, supporting faster connection. However, 5G comes with its own technical challenges, such as those relating to authentication handover and user privacy protection. In 5G, for example, the frequent displacement of the users among the cells as a result of repeated authentication handovers often lead to a delay, contradicting the 5G objectives. Using inefficient authentication handover could also cause performance degradation among heterogeneous 5G cells, and increases the possibility of occurring user privacy and security issues. In this paper, we propose a new authentication approach that utilizes blockchain and software defined networking (SDN) techniques to remove the unnecessary re-authentication in repeated handover among heterogeneous cells. The proposed approach is designed to assure the low delay, appropriate for the 5G network in which users are replaced with the least delay among heterogeneous cells using their public and private keys provided by the devised blockchain component while protecting their privacy. In our comparison between Proof-of-Work (POW)-based and network-based models, the delay of our authentication handover is shown to be less than 1 ms. Also, our approach demonstrates less signaling overhead and energy consumption compared to peer models.

Abstract: The massive growth of mobile users will spread to significant numbers of small cells for the Fifth Generation (5G) mobile network, which will overlap the fourth generation (4G) network. A tremendous increase in handover (HO) scenarios and HO rates will occur. Ensuring stable and reliable connection through the mobility of user equipment (UE) will become a major problem in future mobile networks. This problem will be magnified with the use of suboptimal handover control parameter (HCP) settings, which can be configured manually or automatically. Therefore, the aim of this study is to investigate the impact of different HCP settings on the performance of 5G network. Several system scenarios are proposed and investigated based on different HCP settings and mobile speed scenarios. The different mobile speeds are expected to demonstrate the influence of many proposed system scenarios on 5G network execution. We conducted simulations utilizing MATLAB software and its related tools. Evaluation comparisons were performed in terms of handover probability (HOP), ping-pong handover probability (PPHP) and outage probability (OP). The 5G network framework has been employed to evaluate the proposed system scenarios used. The simulation results reveal that there is a trade-off in the results obtained from various systems. The use of lower HCP settings provides noticeable enhancements compared to higher HCP settings in terms of OP. Simultaneously, the use of lower HCP settings provides noticeable drawbacks compared to higher HCP settings in terms of high PPHP for all scenarios of mobile speed. The simulation results show that medium HCP settings may be the acceptable solution if one of these systems is applied. This study emphasises the application of automatic self-optimisation (ASO) functions as the best solution that considers user experience.

Abstract: Mobile apps are increasingly relying on high-throughput and low-latency content delivery, while the available bandwidth on wireless access links is inherently time-varying. The handoffs between base stations and access modes due to user mobility present additional challenges to deliver a high level of user Quality-of-Experience (QoE). The ability to predict the available bandwidth and the upcoming handoffs will give applications valuable leeway to make proactive adjustments to avoid significant QoE degradation. In this paper, we explore the possibility and accuracy of realtime mobile bandwidth and handoff predictions in 4G/LTE and 5G networks. Towards this goal, we collect long consecutive traces with rich bandwidth, channel, and context information from public transportation systems. We develop Recurrent Neural Network models to mine the temporal patterns of bandwidth evolution in fixed-route mobility scenarios. Our models consistently outperform the conventional univariate and multivariate bandwidth prediction models. For 4G \& 5G co-existing networks, we propose a new problem of handoff prediction between 4G and 5G, which is important for low-latency applications like self-driving strategy in realistic 5G scenarios. We develop classification and regression based prediction models, which achieve more than 80\% accuracy in predicting 4G and 5G handoffs in a recent 5G dataset.

Abstract: The 3GPP long term Evolution or System Architecture Evolution (LTE/SAE) was designed for the dispositioning of the mobile networks towards 4G. The significant hurdle of 4G is about cementing the privacy and security gap. Due to the disclosures in the connectivity of public networks, a single malicious device could jeopardize the operation of a whole network of devices. The key deliverance handling within the 3GPP LTE/SAE is developed to unauthorize the keys that are being attacked and, in result, to alienate the miscreant keys off the chain of network. The proposed article recognizes the attacks that jeopardize the safe connectivity among the stops in the network chain and details the vulnerability of the key deliverance administration to desynchronization attacks. Even though the periodic upgrade of the root could prove to be a fundamental part of the system, the work proposed brings an emphasis on reducing the impact of desynchronization attacks which currently are unable to be prevented efficiently. The main focus of the design is to shed light on the ways the network operators work to confirm the optimal intervals for the periodic updates to reduce the signal weightage while providing secure user mobility. The analysis and model simulations intend to disclose the influence of the period of root key upgrade on integral operational levels such as constellation and user experience. Index terms – Validation and key correspondence, Evolved Packet System (EPS), Key deliverance handling, Bees Algorithm, LTE security

Abstract: Nowadays, the increase in the number of mobile users and cellular traffic leads to new challenges in the fifth-generation (5G) of cellular networks. The increase in the demand for high data rates brings challenges like scalability and flexibility in the 5G network. Software-defined networking (SDN) is a network paradigm that separates the control plane and data plane in the network and ease the management of the network. In this work, an SDN based 5G core architecture is proposed, in order to introduce flexibility and ease of management in the network. Another benefit of using SDN is to make the network vendor-independent. Furthermore, the explanation of initial attachment and handover procedures in the proposed architecture is provided. A network simulator is built to evaluate the performance of proposed architecture, in terms of end-to-end delay, throughput and resource utilization of controller, under different network factors. A performance comparison, in terms of end-to-end delay, between proposed SDN based 5G architecture and traditional 5G architecture is provided. Results show that the proposed architecture provides 18% to 62% less end-to-end delay, under different factors for different procedures, compared to the traditional 5G architecture. A comparison with previous works is also provided, which indicates similar trends in delay between our work and previous studies.

Abstract: The densification of base station (BS) deployments is driving the evolution of network structures towards heterogeneous ultra-dense networks (UDN), making coordinated multipoint (CoMP) a viable and promising transmission solution. However, the BS cooperation regions formed by applying CoMP in the UDN are small and irregular, which causes frequent handover for mobile users. Different from most existing work that focus on the trigger time of handover, we explore how to choose the appropriate BS cooperation set to reduce handover rate. In this paper, we consider movement aware CoMP handover (MACH). By estimating cell dwell time, a user would be intelligently assigned to macro cell or small cell according to its movement trend. To enhance reliability, we further proposed improved MACH (iMACH) to achieve a trade-off between BSs with long dwell time and the current best performed BS for multipoint cooperation while user moving. Using stochastic geometry method, expressions of coverage probability, handover probability and throughput that characterize performance of the proposed schemes are derived. The numerical results indicate that the theoretical analyses fit the simulation results well and the proposed schemes surpass the existing schemes in terms of the aforementioned metrics, and more intelligent and suitable for ultra-dense scenarios.

Abstract: Modern scenarios in robotics involve human-robot collaboration or robot-robot cooperation in unstructured environments. In human-robot collaboration, the objective is to relieve humans from repetitive and wearing tasks. This is the case of a retail store, where the robot could help a clerk to refill a shelf or an elderly customer to pick an item from an uncomfortable location. In robot-robot cooperation, automated logistics scenarios, such as warehouses, distribution centers and supermarkets, often require repetitive and sequential pick and place tasks that can be executed more efficiently by exchanging objects between robots, provided that they are endowed with object handover ability. Use of a robot for passing objects is justified only if the handover operation is sufficiently intuitive for the involved humans, fluid and natural, with a speed comparable to that typical of a human-human object exchange. The approach proposed in this paper strongly relies on visual and haptic perception combined with suitable algorithms for controlling both robot motion{\color{red}, to allow the robot to adapt to human behaviour,} and grip force{\color{red}, to ensure a safe handover}. The control strategy combines model-based reactive control methods with an event-driven state machine encoding a human-inspired behaviour during a handover task{\color{red}, which involves both linear and torsional loads, without requiring explicit learning from human demonstration}. Experiments in a supermarket-like environment with humans and robots communicating only through haptic cues demonstrate the relevance of force/tactile feedback in accomplishing handover operations in a collaborative task.

Abstract: Named data networking (NDN) is one representation and implementation of information-centric networking (ICN) and is considered to be among the most promising designs for the next generation of network architecture. The introduction of NDN into vehicular ad-hoc networks (VANETs) and utilization of its content-centric characteristic to improve data transmission and distribution in VANETs has become a research hotspot in recent years. However, research on mobility support of NDN-based VANETs still faces many challenges. To solve the issue of data transmission path breaking due to Consumer mobility in NDN-based VANETs, this article proposes a novel vehicle tracking-based Data packet forwarding scheme (VTDF) to improve the successful delivery rate of Data packets in mobile environments. In this approach, the urban road structure is divided into complex multi-junction and straight lane scenarios and Data packets are forwarded according to vehicle movement information. Simulations indicated that this vehicle tracking scheme provides a lower average data transmission delay, shorter handover delay between roadside units, and higher data delivery rate for Consumers compared to the standard methods.

Abstract: Low Earth Orbit (LEO) constellations offer superior low latency performance and excellent signal power, however because of satellites inherent fast relative movement, frequent handovers are necessary for maintaining a continuous connection in such constellations. This paper lays an analytic method for estimating the session duration between two consecutive handovers which is an important design parameter that impacts the overall network performance. We focus on recent LEO networks where, due to their high density, it is possible to analytically capture the bounds of their performance using tractable tools from stochastic geometry. The paper studies two possible physical handover mechanisms and compares the analytic results with well-design practical network deployments.

Abstract: Fifth-generation (5G) cellular networks are a promising technology to meet the rapid growth in wireless traffic. Small cells are critical in fulfilling the requirements of 5G networks. A heterogeneous ultra-dense network (HUDN) is an enabling technology consisting of several types of small cells to enhance the performance of 5G networks effectively. A critical issue of HUDN is the cell selection method because the traditional technique for cell selection is inapplicable in such a network. This study proposes a novel adaptive cell selection (ADA-CS) scheme. It adapts to various characteristics of HUDNs and vehicle movements. It performs six phases to select the best base station with which to be associated. Simulation results show that, with low- and medium-speed vehicles, the ADA-CS scheme outperforms the traditional protocol in terms of the average number of handovers by 42.39%. In addition, it is superior to some relevant recent schemes by up to 36.53%. The adaptation feature of the proposed protocol provides additional improvements regarding the average number of handovers with high-speed vehicles. Therefore, it achieves superiority in terms of the average number of handover failures and unnecessary handovers. In addition, the ADA-CS scheme enhances the average achievable downlink data rates and spectral efficiency per vehicle by 3.98% and 2.79% compared with the traditional and the relevant recent schemes.

Abstract: Heterogeneous wireless networks that are used for seamless mobility are expected to face prominent problems in future fifth generation (5G) cellular networks. Due to their proper flexibility and adaptable preparation, remote-controlled unmanned aerial vehicles (UAVs) could assist heterogeneous wireless communication. However, the key challenges of current UAV-assisted communications consist in having appropriate accessibility over wireless networks via mobile devices with an acceptable Quality of Service grounded on the users’ preferences. To this end, we propose a novel method based on cooperative game theory to select the best UAV during handover process and optimize handover among UAVs by decreasing the i) end-to-end delay, ii) handover latency, and iii) signaling overheads. Moreover, the standard design of software-defined network with media-independent handover is used as forwarding switches in order to obtain seamless mobility. Numerical results derived from the real data are provided to illustrate the effectiveness of the proposed approach in terms of number of handovers, cost, and delay.

Abstract: Although millimeter wave (mmWave) is a promising technology in 5G communication, its severe path attenuation and susceptibility to line-of-sight (LOS) blockage result in much more unpredictable outages than traditional technologies. This special propagation property raises a significant challenge to the mobility management in mmWave cellular networks. Since conventional handover policies purely rely on the measurement of signal strength, they would cause a large number of unnecessary handovers due to the frequent short-term LOS blockage by obstacles, imposing high signaling and energy overhead. In this paper, we propose two novel handover mechanisms to reduce unnecessary handovers by carefully deciding the next base station (BS) a user should handover to, so that the new user-BS connection after the handover can last as long as possible. Without prior knowledge of user’s mobility and environment, the proposed handover mechanisms exploit the empirical distribution of user’s post-handover trajectory and LOS blockage, learned online through a multi-armed bandit (MAB) framework. Depending on the contexts extracted from RSS information, two different MAB problems for handover are formulated, which focus on spatial and space-time contexts, respectively, The results of numerical simulations demonstrate that the proposed contextual handover mechanisms significantly outperform existing counterparts on reducing handovers in all simulated scenarios.

Abstract: Visible light communication (VLC) is considered an important complementary technology for extremely high sixth-generation (6G) data transmission and has become part of a hybrid 6G indoor network architecture with an ultradense deployment of VLC access points (APs) that presents severe challenges to user mobility. An adaptive handover mechanism, which includes a seamless handover protocol and a selection algorithm optimized with a deep reinforcement learning (DRL) method, is proposed to overcome these challenges. Experimental simulation results reveal that the average downlink data rate with the proposed algorithm is up to 48% better than those with traditional RL algorithms and that this algorithm also outperforms the deep Q-network (DQN), Sarsa and Q-learning algorithms by 8%, 13% and 13%, respectively.

Abstract: The future directions and challenges for 6G-enabled wireless communication for IoT applications are mainly focused on quality of service (QoS). The selection criteria of mobility management (MM) protocol are mainly the total duration of the delay and packet loss rate during the MM procedure. This is called intelligent handover (IH) to designate a relay with a minimum delay. To solve the problem of handover, media access control (MAC) protocols are used to provide an intelligent protocol for QoS in real-time application in mobility. Moreover, changing the parameter to find the best protocol for mobile stations in WLAN is a good choice. This paper proposed a new QoS structure for the point coordination function that is based on a new intelligent enhanced distribution coordination function that suites with dynamic real-time applications and services. The paper addresses the distributed coordination function (DCF) with QoS-based intelligent mobility management in stations and other scenarios with enhanced distribution coordination function (EDCF) to find the result of throughput, retransmission attempts, delay, and data droop. In this paper, the remote topology comprises a few remote stations and one base station within the remote LAN. All remote stations are found that each station can distinguish a transmission from any other station, and there is portability within the proposed intelligent framework.

Abstract: Conventional and license-free radio-controlled drone activities are limited to a line-of-sight (LoS) operational range. One of the alternatives to operate the drones beyond the visual line-of-sight (BVLoS) range is replacing the drone wireless communications system from the conventional industrial, scientific, and medical (ISM) radio band to a licensed cellular-connected system. The Long Term Evolution (LTE) technology that has been established for the terrestrial area allows command-and-control and payload communications between drone and ground station in real-time. However, with increasing height above the ground, the radio environment changes, and utilizing terrestrial cellular networks for drone communications may face new challenges. In this regard, this paper aims to develop an LTE-based control system prototype for low altitude small drones and investigate the feasibility and performance of drone cellular connectivity at different altitudes with measuring parameters such as latency, handover, and signal strength. The measurement results have shown that by increasing flight height from ground to 170 m the received signal power and the signal quality levels were reduced by 20 dBm and 10 dB respectively, the downlink data rate decreased to 70%, and latency increased up to 94 ms. It is concluded that although the existing LTE network can provide a minimum requirement for drone cellular connectivity, further improvements are still needed to enhance aerial coverage, eliminate interference, and reduce network latency.

Abstract: Reasoning about object handover configurations allows an assistive agent to estimate the appropriateness of handover for a receiver with different arm mobility capacities. While there are existing approaches for estimating the effectiveness of handovers, their findings are limited to users without arm mobility impairments and to specific objects. Therefore, current state-of-the-art approaches are unable to hand over novel objects to receivers with different arm mobility capacities. We propose a method that generalises handover behaviours to previously unseen objects, subject to the constraint of a user's arm mobility levels and the task context. We propose a heuristic-guided hierarchically optimised cost whose optimisation adapts object configurations for receivers with low arm mobility. This also ensures that the robot grasps consider the context of the user's upcoming task, i.e., the usage of the object. To understand preferences over handover configurations, we report on the findings of an online study, wherein we presented different handover methods, including ours, to 259 users with different levels of arm mobility. We find that people's preferences over handover methods are correlated to their arm mobility capacities. We encapsulate these preferences in a statistical relational learner (SRL) that is able to reason about the most suitable handover configuration given a receiver's arm mobility and upcoming task. Using our SRL model, we obtained an average handover accuracy of 90.8% when generalising handovers to novel objects.

Abstract: The space-ground integrated network (SGIN) has attracted growing attention due to its advantages of high-capacity, low-latency and global coverage. To guarantee the security requirements of SGIN, anonymous authentication is an essential approach to addressing severe threats such as unauthorized access and impersonation attack, while payment is another common method in service-oriented applications in order to encourage companies to participate and also prevent insider attackers from enjoying services without paying. Existing anonymous authentication protocols for SGIN either require users to involve in heavy computation especially in dynamic scenarios, or do not consider cross-domain authentication. In this paper, we first introduce the concept of cross-company satellite services, and then address the cross-domain authentication and billing issues in SGIN, i.e., we propose a decentralized anonymous authentication scheme supporting fast handover and also achieve fairness for the billing procedures. To reduce the authentication delays, the authentication process is delegated from ground to satellites, such that users can arbitrarily switch the satellite networks belonging to different companies. Specifically, users can be anonymously authenticated by showing the knowledge of a secret bound with a randomized verifiable credential and connect to different satellite networks through a fast handover authentication protocol building on a blockchain. Even all companies collude, they cannot forge a valid identity credential and access records for a user. In addition, we provide a fair billing mechanism that can prevent malicious users and greedy satellite companies from manipulating the network accessing fees based on a well-designed smart contract. Finally, we demonstrate that the proposed scheme is secure and efficient through security analysis and performance evaluation.