A drone trajectory planner should be able to dynamically adjust the safety–efficiency trade-off according to varying mission requirements in unknown environments. Although traditional polynomial-based planners offer computational efficiency and smooth trajectory generation, they require expert knowledge to tune multiple parameters to adjust this trade-off. Moreover, even with careful tuning, the resulting adjustment may fail to achieve the desired trade-off. Similarly, although reinforcement learning-based planners are adaptable in unknown environments, they do not explicitly address the safety-efficiency trade-off. To overcome this limitation, we introduce a Decision Transformer–based trajectory planner that leverages a single parameter, Return-to-Go (RTG), as a temperature parameter to dynamically adjust the safety–efficiency trade-off. In our framework, since RTG intuitively measures the safety and efficiency of a trajectory, RTG tuning does not require expert knowledge. We validate our approach using Gazebo simulations in both structured grid and unstructured random environments. The experimental results demonstrate that our planner can dynamically adjust the safety–efficiency trade-off by simply tuning the RTG parameter. Furthermore, our planner outperforms existing baseline methods across various RTG settings, generating safer trajectories when tuned for safety and more efficient trajectories when tuned for efficiency. Real-world experiments further confirm the reliability and practicality of our proposed planner.

Virtual network embedding (VNE) is a promising technique enabling 5G networks to satisfy the given requirements of each service via network virtualization. For better performance of the embedding algorithm, it is necessary to automatically detect the network status and provide an optimal embedding decision. However, existing VNE algorithms disregard the long-term effect by focusing on selecting only one virtual network request from the waiting queue, without considering all waiting virtual network requests concurrently. In this study, we propose a hierarchical cooperative multi-agent reinforcement learning algorithm to optimize the VNE problem by maximizing average revenue, minimizing average cost, and also improving the request acceptance ratio. The proposed algorithm applies two reinforcement learning algorithms: 1) two-level hierarchical reinforcement learning to efficiently solve the problem by dividing it into sub-problems, and 2) multi-agent-based cooperative reinforcement learning to improve algorithm performance through the cooperation of multiple agents. In order to evaluate and analyze the proposed scheme from the long-term perspective, four performance parameters are evaluated: revenue, cost, revenue-to-cost ratio, and acceptance ratio. The simulation results demonstrate that the proposed VNE algorithm based on hierarchical and multi-agent reinforcement learning outperforms the existing RL-based approaches.

In this study, a novel exploration method for centralized training and decentralized execution (CTDE)-based multi-agent reinforcement learning (MARL) is introduced. The method uses the concept of strangeness, which is determined by evaluating (1) the level of the unfamiliarity of the observations an agent encounters and (2) the level of the unfamiliarity of the entire state the agents visit. An exploration bonus, which is derived from the concept of strangeness, is combined with the extrinsic reward obtained from the environment to form a mixed reward, which is then used for training CTDE-based MARL algorithms. Additionally, a separate action-value function is also proposed to prevent the high exploration bonus from overwhelming the sensitivity to extrinsic rewards during MARL training. This separate function is used to design the behavioral policy for generating transitions. The proposed method is not much affected by stochastic transitions commonly observed in MARL tasks and improves the stability of CTDE-based MARL algorithms when used with an exploration method. By providing didactic examples and demonstrating the substantial performance improvement of our proposed exploration method in CTDE-based MARL algorithms, we illustrate the advantages of our approach. These evaluations highlight how our method outperforms state-of-the-art MARL baselines on challenging tasks within the StarCraft II micromanagement benchmark, underscoring its effectiveness in improving MARL.

Named Data Networking (NDN) supports the consumer mobility service by letting a consumer reissue an interest. This method is straightforward, but it may cause several drawbacks, including unnecessary handover overhead and long handover delay. We concentrate on the NDN communication model in which the pair of an interest and a data packet is considered a single communication working set (i.e., transaction unit). In this respect, reissuing an interest means creating a new transaction due to the connection damaged by the movement of a consumer. It makes all states of the current transaction useless, and this is where the drawbacks arise. In order to enhance the consumer mobility service, we propose Mobility Link Service (MLS) operated in NDN face which is responsible for management of a connection for a transaction. MLS reuses the existing states of a transaction by establishing a connection for the transaction instead of creating a new one. In addition, MLS in NDN face makes consumer mobility service transparent to the NDN forwarding plane. Therefore, the consumer mobility service and the NDN architecture can evolve independently. The performance evaluation shows that MLS reduces the amount of retransmitted data and handover latency compared with the existing NDN mobility solution.

Software Defined Network (SDN) is widely deployed by using OpenFlow protocol for the implementation of flexible networking. A lot of researches are progressing to adapt OpenFlow to existing network architectures. PMIPv6 is proposed to handle the network-based local mobility using IP tunneling. However, it has some weak points such as IP tunneling overhead and sharing same path for the data and the control planes. In this paper, we propose OpenFlow-based Proxy Mobile IPv6 (PMIPv6) to obtain the advantages of the OpenFlow architecture for PMIPv6 network. The proposed scheme separates the mobility management function from the components of PMIPv6. It preserves the functionalities and messages defined in PMIPv6 but reconstructs components to take the advantages offered by the OpenFlow architecture. The reconstructed components set the flow table of switches located in the path as the controller of OpenFlow. The proposed scheme removes the tunneling to forward user traffic and separates the data and the control planes. OpenFlow-based PMIPv6 offers more flexible deployment architecture.

Recently, due to a explosive growth in the mobile Internet traffic, the problem of excessive data traffic handling on core network and thus scalability problem have been magnified in 3GPP Long Term Evolution/System Architecture Evolution (LTE/SAE) networks. Current LTE/SAE network based on the central packet data network gateway (P-GW) used as mobility anchor cannot deal with such problems. In this paper, we propose a new LTE/SAE network architecture supporting distributed P-GWs and the corresponding distributed mobility management to solve the problems. For this, in addition to the deployment of such distributed P-GWs, we propose a dynamic and distributed mobility management by distributing MMEs (Mobility Management Entities) which dynamically manages the location information of an UEs PDN connection, and also propose a handover procedure of such PDN connections by using the proposed distributed P-GWs and MMEs. The performance of the proposed distributed LTE/SAE network system is compared with the conventional LTE/SAE network system in terms of the P-GW's data processing volume per unit time and the number of valid data sessions accommodated in the LTE/EPC core network.

Wearable smart devices industry is booming up and being highlighted by the market recently as an alternative of post smart phone industry. Wearable smart devices have an intrinsic nature that their visual style should be very important like fashion as well as the sophisticated function is. They also have unique characteristics of industrial ecosystem different from the ecosystem of the smart phone industry. In this paper, we insist that there are a huge number of vertical markets for wearable smart device product and services. We also suggests that the small and medium companies should be more aggressive to advance such vertical markets with the application products and services with components as well as solutions.

Abstract Proxy Mobile IPv6 (PMIPv6) is proposed as a new network‐based mobility protocol and it does not require MN's involving in mobility management. MN can handover relatively faster in PMIPv6 than in Mobile IPv6 (MIPv6) because it actively uses link‐layer attachment information and reduces the movement detection time, and eliminates duplicate address detection procedure. However, the current PMIPv6 cannot prevent packet loss during the handover period. We propose the Smart Buffering scheme for seamlessness in PMIPv6. The Smart Buffering scheme prevents packet loss by proactively buffering packets that will be lost in a current serving mobile access gateway (MAG) by harnessing network‐side information only. It also performs redundant packet elimination and packet reordering to minimize duplicate packet delivery and disruption of connection‐oriented flows. To fetch buffered packets from a previous MAG, a new MAG discovers the previous MAG by using a discovery mechanism without any involvement of an MN. We verified the effectiveness of Smart Buffering via simulation with various parameters. Copyright © 2009 John Wiley & Sons, Ltd.

Recently, wireless and mobile communication networks have become increasingly popular and the huge number of smart mobile devices and applications has brought the mobile operators with challenges from various aspects. This trend will continue to affect the way in which we live, work, and play with many smart and innovative services, and the intensive mobility control messages and data will give great impact on the traditional wireless and mobile communication networks. For this reason, the mobility management support is one of very important issues for the future generation of wireless and mobile networks and services, and the design of efficient and robust mobility management is one of the most challenging research tasks. Observing the great need for an in-depth research of the mobility management in both academia and industry, we have put together this special issue through an open call for papers. More than 10 high-quality papers from all around the world were submitted. Although many of them were of high quality, we had room for only three papers that best fit the theme. To guarantee higher quality of this special issue, we also have selectively collected four expanded papers from the proceedings of MobiWorld 2008 workshop while inviting two comprehensive surveys. Accordingly, this special issue brings together nine papers. The first two papers are devoted to review and survey recent developments and methods of mobility management, and the others propose and analyze some of the most interesting and innovative solutions dealing with the mobility management in wireless mobile networks. The paper “Next generation mobility management: an introduction” by F. Richard Yu, Vincent W. S. Wong, Joo-Han Song, Victor C. M. Leung, and Henry C. B. Chan reviews recent research trend and developments in location management, and surveys methods for inter-system handover management between heterogeneous systems. It classifies the inter-system handover management schemes according to the protocol layer, so that the readers can gain in-depth insight into the topic. It also provides open problems and research direction for the next negation mobility management. Recently, communication devices are being installed in more and more vehicles and roadside infrastructure. In the near future, traveling vehicles will be able to communicate while forming rapidly changing ad hoc networks. The paper “Mobility and Handoff Management in Vehicular Networks: A Survey” by Kun Zhu, Dusit Niyato, Ping Wang, Ekram Hossain, and Dong In Kim presents a good comprehensive survey on existing mobility management works for both vehicle-to-vehicle and vehicle-to-infrastructure communications in vehicular networks, and also provides several open research issues of the topic. The following four papers refer to the proxy mobile IPv6 (PMIPv6) which is a famous mobility management protocol recently standardized by IETF. PMIPv6 is a representative network-based localized mobility management protocol and has been of great interest to both academia and industry. Unlike host-based IP mobility management protocols, PMIPv6 does not require the participation of mobile nodes in mobility signaling. The paper “Implementation and analysis of proxy MIPv6” by Jianfeng Guan, Huachun Zhou, Zhiwei Yan, Yajuan Qin, and Hongke Zhang analyzes the singling cost of PMIPv6, provides their test-bed implement to evaluate its performance, and shows that its performance is better than the other mobility management protocols. The paper “Smart Buffering for seamless handover in Proxy Mobile IPv6” by Hyon-Young Choi, Kwang-Ryoul Kim, Hyo-Beom Lee, Sung-Gi Min, and Youn-Hee Han presents a PMIPv6 buffering scheme using only network-side information to prevent packet loss by proactively buffering packets that will be lost during handover, and also provides redundant packet elimination and packet reordering methods to minimize duplicate packet delivery and disruption of connection-oriented data flows. The paper “The applicability of virtual interface for inter-technology handovers in Proxy Mobile IPv6” by Ryuji Wakikawa, Sawako Kiriyama, and Sri Gundavelli analyzes the required software function on the mobile node for performing inter-technology handovers and investigates the applicability of virtual interface support available in Linux for implementing the PMIPv6-based inter-technology handover. The paper “QoS aware dynamic route optimization for Proxy Mobile IPv6 networks” by A. Dev Pragad, Vasilis Friderikos, Paul Pangalos, and A. Hamid Aghvami provides a QoS aware dynamic route optimization scheme where the network identifies the lower QoS sessions, and establishes a binding update with the correspondent node (CN) rather than with the LMA. The paper “A Cross-Layer Partner-Assisted Handoff Scheme for Hierarchical Mobile IPv6 in IEEE 802.16e Systems” by Yuh-Shyan Chen and Kun-Lin Wu presents a new partner-assisted handoff mechanism based on cross-layer approach by the combination of layer 2 and layer 3 in hierarchical mobile IPv6 which is a protocol standardized by IETF. The paper “Soft handoff support for SIP-NEMO: design, implementation, and performance evaluation” by Shun-Ren Yang, Ya-Jun Huang, and Chun-Wei Chiu provides a soft handoff mechanism to effectively reduce the handoff disruption time which may be long in thesession initiation protocol and network mobility (SIP-NEMO). The paper “An end-to-end framework of transport layer mobility management” by Yi Wu, Yanqun Le, and Dongmei Zhang extends the TCP migrate work by resolving the simultaneous mobility issue that the existing transport layer mobility schemes do not support and proposes an improved end-to-end framework of TCP migrate scheme through handover redirection and transmission resuming. We would like to thank all the authors for their great work and for considering this special issue for submitting their papers. We would like to extend our gratitude to the anonymous reviewers who spent much of their precious time reviewing all the papers and providing substantive comments on paper improvements. We also would like to thank the devoted staff of Wiley for their high level of professionalism, and particularly express our sincere thanks to the Editor-in-Chief of WCMC, Professor Mohsen Guizani, for inviting us to edit this special issue and for their continuing keen interest. It has been a pleasure to put together this special issue on this very timely topic and we hope you enjoy it.

The best way to conserve energy in wireless sensor networks is to change the radio interface state to sleep mode. The sensors in sleep mode conserve energy, whereas the sensors in active mode use their energy to continue to monitor the target. How sensors are scheduled between active and sleep modes affects the lifetime of the sensor network.

One of most critical issues in power-constrained wireless sensor networks is to maximize the network lifetime. Recently, studies have been made on scheduling sensor activity to prolong network lifetime. In this paper, we address the maximum set covers (MSC) problem to maximize the network lifetime and propose an energy-efficient sensor scheduling algorithm for the MSC problem based on the branch and bound approach. Simulation results show that the proposed algorithms can contribute to extending the network lifetime and its performance is better than the existing greedy-based algorithm.

Efficient deployment of sensors is an important issue in wireless sensor networks. If we deploy sensors randomly by our hands or carriers only, some unlucky places are not covered forever. In this paper, we propose distributed self-deployment schemes of mobile sensors. At first, sensors are deployed randomly. They then calculate the next positions locally by utilizing the proposed schemes and move to them. The locations of the sensors are adjusted round by round so that the coverage is gradually improved. By using Voronoi diagram and centroid (geometric center), we design two schemes, named Centroid (centroid-based scheme) and Dual-Centroid (dual-centroid based scheme). We also measure the performance of the proposed schemes and the existing schemes, and show that the proposed schemes get better results.

Recently, the IETF NETLMM working group is standardizing a network-based localized mobility management (NETLMM) protocol called proxy mobile IPv6 (PMIPv6), yet the research on NETLMM is still in its early stage while it has attracted a fair amount of critical attention both in the telecommunication and the Internet communities. Unlike previous host-based mobility management protocols such as mobile IPv6 (MIPv6), hierarchical mobile IPv6 (HMIPv6), and fast handover for mobile IPv6 (FMIPv6), PMIPv6 has salient features and is expected to expedite the real deployment of IP mobility support protocol by using only collaborative operations between the network entities without mobile node (MN) being involved. In this paper, we analyze and compare the handover latency of PMIPv6 with those of the various existing host-based IP mobility management protocols. In addition, we show good efficacy of the desirable features and key strengths of PMIPv6. Numerical results demonstrate that (1) the handover latency of PMIPv6 is much lower than those of MlPv6 and HMIPv6, and (2) the handover latency of PMIPv6 becomes lower than that of FMIPv6 in case the wireless link delay is greater than the delay between mobile access gateway (MAG) and local mobility anchor (LMA).

In this paper, we propose the seamless video transmission scheme over wireless LANs during fast handover in Mobile IPv6. In fact, a mobile node cannot receive the IP packets during handover. A number of extensions to fast handover for mobile IPv6 have been introduced to recover its weakness. Fast handover algorithm in mobile IPv6 allows the new access router in the adjacent cell to pre-buffer the data packets of a mobile node to prevent packet loss. In a mobile communication environment, however, transmission of multimedia data should consider the realtimeliness of the data. We focus on the multimedia data delivery during fast handover in mobile IPv6 environment

In recent years, there has been a rapid growth in the need to support moving hosts and moving networks in IPv6-based mobile networks. As the number of such hosts and networks grows, so will the demand for delay sensitive real-time applications, such as voice over IP (VoIP), that require seamless handover. Two well-known approaches to reduce the handover latency have been proposed in the literature: proactive and reactive approaches. While proactive handover is known to generally outperform reactive handover, its reliability and practicality are still questionable since it basically depends on predictive information which may be unreliable in some cases. In this paper, based on the standard specification for IPv6 mobility support, we analyze the existing movement detection and address configuration procedures which are the main components of reactive handover approach. We also propose a novel reactive handover procedure which employs our optimized movement detection and address configuration schemes. The proposal is simple and robust because it does not need any predictive information and it requires a minimum number of signaling messages. The performance evaluation shows that the proposal substantially reduces the signaling load on wireless/wired networks and its handover latency is reduced enough to support seamless services

IETF mobile Internet protocol version 6 and its fast handover protocol are proposals for handling routing of IPv6 packets to mobile nodes that have moved away from their home network. To do this, each time a mobile node moves to a new location, iit configures and confirms it temporal IP address. In this paper, we study the impact of the address configuration and confirmation procedure on the their IP handover latency. We first argue that the current strategies for them are unnecessarily slow, hampering the use of current proposals for real-time traffic. We present a new scheme which can be a substitute of the current strategies. The underlying objective of our scheme is to completely eliminate the latency taken by the address configuration and confirmation from the whole handover latency. Further, a mathematical analysis is developed to show the benefits of our scheme. In this analysis, various parameters are discussed to analyze the existing proposals, while our approach focuses on the reduction of handover latency.

Abstract The Hierarchical Mobile IPv6 (HMIPv6), which is based on the Mobile IPv6 (MIPv6), has been proposed by IETF to reduce registration control signaling. It separates micro‐mobility from macro‐mobility with the help of an intermediate mobility agent, called the mobility anchor point (MAP), and exploits a Mobile Node's (MN's) spatial locality. However, all packets from a Correspondent Node (CN) to an MN are delivered through the MAP. That causes delay in packets delivery and the congestion of packets in the MAP so that it results in deterioration of network capability. To alleviate these problems, we propose a Hierarchical Mobile IPv6 protocol using not only spatial locality but also temporal locality. We introduce a profile for management of these locality information. According to the information in the profile, some packets are directly delivered to an MN, if MN seems to reside for a long time in the current subnet. Also, we introduce a handover scheme with the help of an L2 trigger, so that the proposed scheme takes nearly the same handover delay time as HMIPv6. The other contribution of this paper is to suggest a mathematical modeling and analysis of network traffic costs, MAP processing costs and handover latency for both HMIPv6 and the proposed scheme. Copyright © 2004 John Wiley & Sons, Ltd.

Many dynamic location update schemes such as time-based, movement-based, and distance-based; have been studied in the location management of mobile communication. Also there are many studies that improve these schemes adaptively using mobile nodes' call and mobility patterns. These schemes usually use the prediction-based algorithms for mobile nodes' mobility patterns. However those need complicated computation such as heuristic algorithm. Those schemes' management cost are various for mobile nodes' diverse mobility patterns. In this paper we propose a novel approach in which the location management costs are rarely affected by mobile nodes' mobility patterns. The basic idea is to use the velocity of a mobile node, which is represented by the combination of two thresholds: time threshold T and distance threshold D. The update process is triggered by the change of mobile nodes' velocity, that is two thresholds. These values are adjusted by simple algorithm whenever a location update occurs. Also, we use stepwise paging scheme using the mobile nodes' velocity in order to reduce the paging cost. We compare our scheme with the distance-based scheme through numerical analysis. Finally, we show that our proposed scheme is better than the distance-based scheme with an optimal distance threshold value for most mobility patterns.

Recently, hierarchical architecture for location databases has been proposed in order to accommodate the growing number of PCSs user. With the 3-level hierarchical database architecture, which is compatible with the current cellular mobile systems, newly developed additional databases, including the regional location database (RLR), are positioned between the HLR and the VLRs. We propose an efficient cache scheme, the Double T-thresholds Location Cache Scheme, could reduce the network and database costs to lookup a portable using the 3-level architecture. The idea behind our proposed scheme is to use two pieces of cache information, VLR and RLR, which are serving the called portables. These two pieces are required in order to exploit not only the locality of a registration area (RA) but also the locality of a regional registration area (RRA), a wide area covered by the RLR. We also use two threshold values in order to determine whether the two pieces are obsolete. The cost analysis presented in this paper shows that the double T-thresholds location cache scheme significantly reduces network and database costs for most patterns of portables.