Multi-Command Posts (MCPs) in tactical ad hoc networks were proposed to solve network congestion and battery depletion on nodes around a single CP. However, since current model-driven approaches for MCPs often rely on simplified metrics, they fail to adapt to the harsh dynamics of the environment. To address this issue, this paper presents a new approach called SRRL (Stability and Recovery-aware Reinforcement Learning), a Q-learning based routing protocol designed to operate effectively in such conditions. SRRL consists of two phases: the source node first selects a target MCP by assessing the viability of each destination based on learned values and one-hop link stability; then, each forwarding node makes hop-by-hop decisions based on a score that reflects path stability, link quality, and residual energy. The influence of energy in this score is adjusted dynamically according to the node’s current state, and a lightweight local recovery mechanism improves delivery robustness. SRRL achieves up to an 8.5% higher packet delivery ratio, enables 13.6% more nodes to remain operational, and extends the time to first node failure by 41.1% compared to conventional Qlearning methods, particularly under high mobility and heavy traffic conditions.

We consider a novel active learning problem motivated by the need of learning machine learning models for health monitoring in wireless body area network (WBAN). Due to the limited resources at body sensors, collecting each unlabeled sample in WBAN incurs a nontrivial cost. Moreover, training health monitoring models typically requires labels indicating the patient's health state that need to be generated by healthcare professionals, which cannot be obtained at the same pace as data collection. These challenges make our problem fundamentally different from classical active learning, where unlabeled samples are free and labels can be queried in real time. To handle these challenges, we propose a two-phased active learning method, consisting of an online phase where a coreset construction algorithm is proposed to select a subset of unlabeled samples based on their noisy predictions, and an offline phase where the selected samples are labeled to train the target model. The samples selected by our algorithm are proved to yield a guaranteed error in approximating the full dataset in evaluating the loss function. Our evaluation based on real health monitoring data and our own experimentation demonstrates that our solution can drastically save the data curation cost without sacrificing the quality of the target model.

Age of Information (AoI) is a new metric that indicates the freshness of information; especially, it is used to design schedulers in 5G networks. Recently, various AoI schedulers have been proposed to guarantee AoI deadlines for emerging applications in which the timeliness of information is critical. However, these schedulers face challenges in meeting the deadlines for all source nodes in situations wherein system resources are limited. To overcome this limitation, a violation-tolerant scheduler has been proposed; however, it does not consider the variance of violations over consecutive data, thereby resulting in significant information deficiencies over long periods of time. In this study, we consider the problem of scheduling a stream with ($m, k$)-firm deadlines, wherein at least$m$of any$k$consecutive data points must satisfy their deadlines. To address this problem, we propose a dynamic priority assignment technique and a priority-based physical resource block allocation algorithm. In addition, we introduce an open radio access network-based system model to enable practical deployment of the proposed solution. We built a 5G simulation environment using ns-3 and captured performance variations under realistic deployment scenarios.

Age of information (AoI) is used to evaluate the performance of 5G health monitoring systems because stale data can be fatal for patients with serious illness. Recently, grant-free ultrareliable and low latency communications (URLLC) have shown greater potential of minimizing AoI than conventional grant-based approaches; however, existing grant-free schedulers cannot provide guaranteed performance in 5G health monitoring systems because they involve two fundamental problems in time and frequency domains, namely the joint scheduling problem and physical resource block (PRB) allocation. In this study, we investigate two resource allocation problems for the first time, aiming to enable grant-free URLLC to minimize AoI in 5G health monitoring systems. Specifically, we propose two adaptive solutions based on an open radio access network-coordinated wireless system: 1) a joint scheduling algorithm and 2) an adaptive PRB allocation algorithm. To verify the effectiveness of the proposed solutions, we built a simulation environment similar to a real health monitoring system and captured the performance variations under realistic deployment scenarios.

Multi-objective optimization (MOO) has been a topic of intense interest in providing flexible trade-offs between conflicting optimization criteria in wireless body area networks (WBANs). To solve diverse multi-objective optimization problems (MOPs), conventional resource management schemes have dealt with the classic issues of WBANs, such as traffic heterogeneity, emergency response, and body shadowing. However, existing approaches have difficulty achieving MOO because, despite the personalization of WBANs, they still miss the new constraints or considerations derived from user-specific characteristics. To address this problem, in this paper, we propose an adaptive scheduling and power control scheme for MOO in personalized WBANs. Specifically, we investigate the existing scheduling and power control schemes for solving MOPs in WBANs, clarify their limitations, and present two feasible solutions: priority-based adaptive scheduling and deep reinforcement learning (DRL) power control. By integrating these two mechanisms in compliance with the IEEE 802.15.6 standard, we can jointly improve the optimization criteria, that is, differentiated quality of service (QoS), transmission reliability, and energy efficiency. Through comprehensive simulations, we captured the performance variations under realistic WBAN deployment scenarios and verified that the proposed scheme can achieve a higher throughput and packet delivery ratio, lower power consumption ratio, and shorter delay compared with a conventional approach.

IEEE 802.15.6, which is the standard for wireless body area networks (WBANs), defines a unique link allocation interval called the managed access phase to meet the QoS requirements of medical applications. The hub grants an uplink allocation interval to the node according to predetermined scheduling policies; however, the IEEE 802.15.6 standard does not consider user priorities in the uplink scheduling. To address this problem, many priority-based link scheduling algorithms have been proposed; however, these algorithms ignore the unique characteristics of WBANs, such as changes in body posture and damage to body tissue, thereby leading to a waste of resources. To overcome these limitations, in this study, we propose three scheduling parameters that are suitable for WBANs, and logically determine the relationship between the proposed parameters using the multi-criteria decision making (MCDM) method. Furthermore, a priority-based dynamic link scheduling algorithm is proposed, which is based on the results of the MCDM. The simulation results prove that our proposed approach can balance the resource allocation, while maintaining the performance of high-priority nodes in terms of throughput, delay, and power consumption.

In wireless body area networks (WBANs), the routing layer has a unique challenge that needs to be addressed by novel temperature-aware routing mechanisms to minimize the increase in body temperature. However, existing temperature-aware routing studies do not consider the compatibility with the core functions of the MAC layer for routing support, such as a two-hop star topology extension or two-hop scheduled resource allocation. The lack of interaction with the MAC layer can lead to a poor performance or inaccurate performance evaluation. To solve this problem, in this paper, we outline the key functions for routing support defined in the IEEE 802.15.6 and design the new upper-layer components required for temperature-aware routing. Subsequently, we implement a simple temperature-aware routing protocol to compare the performance with previous studies. The simulation results prove that our approach can derive a practical routing performance in terms of delay, packet delivery ratio, and power consumption, among other factors.

Because of dynamic topology in ad hoc networks, many routing protocols as well as service discovery protocols are mainly dependent on flooding algorithms. However, despite of its great role of flooding algorithm in wireless ad hoc networks, experimental study for small scale ad hoc networks has not been explored well yet. To solve this problem, in this paper, we implement the several flooding algorithms on Raspberry Pi and evaluate the performance of them. We present the details of the implementation and packet delivery ratio ratio where small scale ad hoc networks are deployed.

In this paper, we present a new load balancing algorithm based on multi-criterion decision making (MCDM) to select efficient relay UAV. For MCDM operation, buffer occupancy, remaining energy and link quality given by number of retransmission are consider. Through simulation result, we demonstrate that the proposed scheme can improving packet delivery ratio and end-to-end delay by reducing the congestion significantly.

In Mobile-Assisted Sensing, a number of mobile devices may be gateways. Thus, the gateway selection procedure should be performed whenever multiple gateways attempt to acquire data from a sensor. Owing to different capacity and status of each mobile gateway, a selected gateway has great impact on the data collection. In this paper, we present possible criteria for gateway selection and compare their performance.

In this paper, we propose a new enhanced temperature aware routing protocol to assign the temperature of node by considering current temperature and expected rise caused by the packets in the buffer. Also, two hops ahead algorithm is employed to ensure further packet forwarding to the sink. The simulation results are shown to prove that the proposed scheme is able to increase packet delivery ratio and network lifetime.

In this paper, we present a new spectrum aware routing protocol that is based on the number of available channels obtained by prediction algorithm and number of hops to reduce the end-to-end delay in cognitive radio ad hoc networks. Simulation results are given to demonstrate the shorten end-to-end delay in the aspects of mobility speed and varying number of channels.

In this paper, we present dynamic clustering scheme and hierarchical routing for Unmanned Aerial Vehicle (UAV) relayed tactical ad hoc networks. The simulation results are given to prove the higher packet deliver ratio and shorter end-to-end delay through the proposed scheme than typical routing protocol in tactical ad hoc networks.

rough wireless sensor networks (WSN), we can acquire the various interesting event information around sensor nodes through multihop communications.In WSN, there are two types of applications, that is, event or query based.Commonly, in these application, the value on each sensor node is very sensitive to delay or latency.So, it is strongly required to deliver data to sink node within the deadline since data received aer the deadline is not acceptable at all in WSN. e good example of application demanding real-time communication in WSN includes tracking of moving object and intrusion detection.However, compared to typical networks, it is very difficult to achieve real-time communication in WSN.Severe constraints such as limited computing power and narrow bandwidth are not suitable to provide real-time communication accordingly.So, a number of important issues and research challenges have to be addressed to provide realtime communication in WSN.Based on this demand, this special issue is planned to contribute to advances in real-time communications in WSN.While considering our objective, editors believe that this special issue provides collection of articles on networking technique in real-time communications.We have selected valuable papers by evaluating several aspects such as relevance to special issue and novelty of solution.e topic of these papers is roughly categorized into the following areas: multichannel transmission, MAC protocol, testbed for routing protocol, and comprehensive survey for real-time in WSN.

Generally, various traffic requirements in wireless sensor network are mostly dependent on specific application types, that is, event-driven, continuous, and query-driven types. In these applications, real-time delivery is one of the important research challenges. However, due to harsh networking environment around a node, many researchers usually take different approach from conventional networks. In order to discuss and analyze the advantage or disadvantage of these approaches, some comprehensive survey literatures were published; however they are either out of date or compiled for communication protocols on single layer. Based on this deficiency, in this paper, we present the up-to-date research approaches and discuss the important features related to real-time communications in wireless sensor networks. As for grouping, we categorize the approaches into hard, soft, and firm real-time model. Furthermore, in all these categories, research has been focused on MAC and scheduling and routing according to research area or objective in second level. Finally, the article also suggests potential directions for future research in the field.

A small device-based, low-rate, short-range wireless radio communication often hampers high reliability in wireless sensor networks. However, more applications are increasingly demanding high reliability. For this requirement to be met, various approaches have been proposed in a layered manner. Among those, MintRoute is a well-known network layer approach to develop a new metric based on link quality for path selection toward the sink. By choosing the link with the highest measured value, the proposed approach can afford a higher possibility to transmit a packet over the link without error. However, there are still several issues to be discussed during operations. In this paper, we propose how to improve the MintRoute protocol through several revised algorithms, including the development of a new metric, a parent selection considering distance and level from the sink node, and a fast recovery method against failures. Simulations and analysis are performed to validate the suitability of reduced end-to-end delay and fast recovery from failures.Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, we propose a novel scheme of how to efficiently and reliably deliver multimedia real-time streams in wireless sensor networks. To specify the property of streams, a multimedia stream is modeled as an m,k-firm stream that is known to have the characteristics of weakly hard real-time system. In addition, a distributed, measurement-based routing scheme for m,k-firm streams is newly proposed while considering several constraints on node as well as on communication medium. Simulations and their analysis are provided to validate the suitability of traffic modeling, reduced dynamic failure probability, and extended network lifetime when the proposed routing protocol is employed. Copyright © 2013 John Wiley & Sons, Ltd.

Due to the stringent energy constraint wireless "s, network management cost for lifetime becomes" "sensor node" "one of the crucial issues in designing wireless sensor networks (WSNs). In such situation, guaranteed network lifetime is more preferred than unpredictable pro-long one. However, despite of its importance and necessity in real world deployment, few research works have been proposed to solve this complex problem by ideal approach with the lack of applicability. In this paper, we present a new centralized scheduling mechanism to guarantee network lifetime to a pre-determined time while maintaining k-coverage of network field. In order to guarantee network lifetime, each node are enforced to remain steadfast in the idle state for a known duration of its lifetime. In addition, the scheduling algorithm is extended to provide real-time service by adjusting transmission range according to current energy state of a sensor node. These two core functions are implemented by deciding each nodes role in the next round according to nodes energy consumption and active time history in decision phase. The performance of proposed scheme is compared with well-known A-MAC and MMSPEED protocols in terms of guaranteed lifetime and real-time respectively.

Typical mobile P2P protocols largely relied on inflexible techniques such as, flooding, replicating, random walks and selective forwarding to route queries and discover objects of interest, which incur a relatively high search time due to remarkable network traffic, multiple copies and duplication of query messages. Recently proposed P2P protocols are able to reduce search time but due to peer mobility, these protocols cause low hit rate and high overhead. Thus, this article proposes novel fuzzy controller based probabilistic walk for unstructured mobile P2P networks to reduce search time. The search time is reduced by jumping a query walker to 2-hop away selected ultrapeer through fuzzy controller. Furthermore, each ultrapeer share its pong cache with its directly connected ultrapeer to increase hit rate and reduce network overhead. Simulations show that the fuzzy search controller gives better performance than the competing protocols in terms of reducing response time by 10% and increasing hit rate by 15% in different mobility scenarios.

Delay Tolerant Networks (DTN) has been proposed to provide communication between nodes where they are intermittently connected. In this situation, a new routing approach, store-carry-forward, is used to deliver data between source and destination. Even though long delay is acceptable in DTN, however some applications occasionally require predetermined bounded delay. To meet this requirement, some approaches have been proposed. However, due to dependency on assumption such as infinite buffer size and mobility pattern, they suffer from deployment problem. To defeat this problem, in this paper, we propose a new probabilistic epidemic routing with time constraint and delay. We adjust forwarding probability on each node depending on bounded delay, elapsed time, and current networks environment. Simulation results reveal that the proposed scheme can meet required delivery ratio and consume little resource rather than original one and competitive protocol.

Previous works for airborne ad-hoc networks based on full connectivity is not suitable for actual situations in the sky. To solve this problem, in this poster, we propose a new DTN routing protocol by introducing multi-copy scheme with utility based forwarding. The proposed scheme introduces bounding box for dense deployment and new utility metric for data packet routing for sparse deployment. Simulation results are given to demonstrate the performance enhancement in sparse networks.

As the technology of multimedia applications in Wireless Sensor Networks (WSNs) is highly desired nowadays, how to guarantee real-time service becomes one of the biggest research challenges in this area. Even though lots of related works have been conducted to meet this requirement in several ways, the specific traffic model for multimedia applications has not been taken yet. It makes these new approaches not adaptable in real deployments. To solve this problem, in this paper, we model the real-time streams of multimedia applications with (m, k)-firm guarantee, using the firm real-time property it contains. A local transmission status indicator modified based on stream DBP (Distance-Based Priority), called L_DBP (local-DBP), is used to monitor the statement of delivery to the next hop and indicate network faults such as congestion and link failure during transmissions. By the contributions of both L_DBP and stream DBP, a novel geographic routing protocol is proposed to meet the requirements of real-time streams, by making routing decisions while considering timeliness and reliability features together. Simulation results reveal that (m, k)-firm is a good traffic model for multimedia sensor networks and the proposed routing protocol can efficiently avoid stream end-to-end dynamic failure, which is considered to be the main reason of QoS performance degradation.

In this paper, we give a framework to reduce delivery failure influence in overlay multicast. Unlike previous efforts based on duplicated forwarding, our scheme builds another type of overlay data delivery tree (DDT), which is adaptively reconstructed based on the number of measured packet delivery ratio while guaranteeing end-to-end delay bound. Through practical simulation results, we analyzed packet delivery ratio, control overhead, end-to-end delay and number of replicated packets.

Due to unpredictable topology change and frequent link failure, it is becoming evidently a major challenge to provide a stable route between source and destination in mobile ad hoc networks (MANET). Unlike previous multipath routing schemes for redundancy and unicast routing protocol utilizing longest route expiration time supported by GPS, we develop a framework to establish the most stable route based on measured frequency of link failure, and available battery, as well as the number of actual connections. To evaluate the performance of the proposed scheme, we also provide practical simulation results with multipath routing and unicast routing protocol in terms of packet delivery ratio, control overhead, and hop counts, as well as end-to-end delay. Through analysis of simulation results, we demonstrate that our scheme shows better performance than the general unicast routing protocol as well as similar packet delivery ratio to the multipath routing protocol with less maintenance overhead.

Various ALM (application layer multicast) mechanisms have been suggested to remove the barriers that block deployment of IP multicast. However, most ALM mechanisms do not consider the host group model, which is not a problematic portion, but advantageous feature of traditional IP multicast in terms of scalability, robustness, security, and transparency. Furthermore, those mechanisms build an overlay multicast network for data delivery mostly based on a simple measurement, with a few metrics, without directly considering the IP network topology. Thus, they might suffer some inefficiency, such as long join delay and large control overhead. We propose a scheme to take advantages of both IP multicast and ALM, based on two principal design factors. By adopting the host group model, our scheme can inherently acquire network topology information used to get rid of application level routing inefficiency, and to gain additional efficiency for many group members. Also, we exploit topology-awareness to reduce join delay and localize group members so that controls for setting up and maintaining overlay networks can be limited in a domain. Overall network performance is enhanced with our scheme by building an overlay network based on performance factors associated with network characteristics using a hierarchical structure.

Fair call admission control (CAC) for heterogeneous services with different traffic properties, such as wideband and narrowband calls, is an important subject in wireless networks. B.M. Epstein et al. (see IEEE JSAC, vol.18, no.3, p.523-34, 2000) proposed a novel CAC scheme, independent multiclass one-step prediction with complete sharing and reservation (IMOSP-CS and IMOSP-RES), which ensures that wideband calls are not blocked more than narrowband calls. However, such an IMOSP algorithm can often lead to some abnormalities, not guaranteeing call blocking probability (CBP) fairness and high resource utilization, depending on traffic behavior. It is mostly because the resource adjustment algorithm in IMOSP simply increases or decreases only one bandwidth unit independent of traffic properties. These abnormalities can be easily seen where offered traffic load between services differs greatly. We propose a novel CAC scheme to admit wideband and narrowband calls fairly regardless of traffic behavior. Also, we propose a new resource management algorithm to enhance utilization. These improvements are largely dependent on seeking a reservation partition for each class based on prediction and measurement. Simulation results demonstrate that our CAC scheme actually achieves CBP fairness for wideband and narrowband calls and also improves resource utilization.

We propose a new adaptive and predictive measurement-based fair call admission control policy. The objective of a new admission policy is to reduce computation overhead and rapidly re-allocate resources to meet desired quality of service (QoS) demands. With numerical analysis, we evaluate QoS constraints by using queuing model which is described by a two-dimensional continuous-time Markov chain. By comparing results of analytical model with one of event-driven simulation, we validate the accuracy.

Previous multicast schemes for MANET (mobile ad hoc networks) are mostly classified as tree-based schemes and mesh-based schemes depending on their multicast delivery structure. Tree-based schemes cannot cope with network mobility due to frequent tree reconfiguration. On the other hand, mesh-based schemes waste unnecessary resource due to delivery along multiple paths. We propose to use an overlay multicast to handle network mobility efficiently with minimized resource. In our scheme, DDT (data delivery tree) can remain static as long as unicast route between members that are related to data forwarding remains reachable. Thus, it can not only minimize the effects of network mobility, but also bring about low additional control overhead. Such distinct advantages are specifically evaluated through the results of the simulation.

Mobile IP (MIP) is proposed to ensure packet routing to a mobile host in the Internet regardless of the attachment point. MIP defines two functional entities, home agent (HA) and foreign agent (FA) to manage the mobile host location. Also, MIP defines the tunneling mechanism to deliver packets that are destined for the mobile node's home address. This tunneling mechanism has difficulties in adapting to the IntServ and DiffServ Internet service architectures. Since both services identify the service session as three-tuples - destinations IP address, IP protocol number and destination port - a new different service session must be defined over the IP tunnel. Current MIP QoS works concentrate on how to guarantee QoS over the IP tunnel and map it to the end-to-end service session, but seem to neglect the host mobility supporting protocol. We regard this protocol as an important factor. The current protocol has a hierarchical architecture with both micro and macro mobility. So, if MIP QoS can be organized in the same hierarchical architecture, better QoS can be obtained. Since MIP can support host mobility in a macro network, IntServ and Diffserv must be applied in this section. However, since several schemes are proposed to support fast handoff in the micro level, several QoS mechanisms may be applied in this level. This paper specifics a hierarchical scheme which uses not only aggregate RSVP flows between domain level agents, but also a specific local policy between domain level agent and mobile host in a domain.

This paper proposes the TPED MBAC (two-phase edge-to-edge distributed measurement based admission control) mechanism that provides the guarantee of user QoS requirements and the fairness of blocking probability between flows traversing different path lengths in large IP networks. The proposed mechanism has two provisioning phases, the quantitative provisioning phase and the qualitative provisioning phase, in admission control and performs WRR scheduling based on the hop counter for probing packet transmission. Additionally, the proposed mechanism uses the optimized probing packet rate instead of the peak rate. For the performance evaluation of the proposed mechanism, we present simulation results in terms of the fairness of blocking probability and the loss probability using the ns-2 simulator.