The papers in this special section focus on data analytics for public health care. Growing and intensive attention for the use of data analytics in healthcare due to its proven benefits to gain insights on the macro and micro depths to support decisionmaking at the patient, clinical, bench side and business levels. Health data analytics contributed to the improvements to patient care, faster and more accurate diagnoses, preventive measures, more personalized treatment, narrow the gap between bedside and bench side and provide more informed decision-making. However, the recent pandemic of COVID-19 draw the world attention to need to extend the power of data analytics beyond the legacy data channels including Electronic Health Records (EHRs) and Patient Portals. Data analytics can assist population health management in improving patient outcomes, enhancing care management, and address social determinants of health. As the population health analytics continues to grow in the healthcare space, healthcare systems must be able to gather data from multiple sources, apply variety of data analytics (e.g., Descriptive Analytics, Predictive Analytics Prescriptive Analytics), and manage the provide insights for the population.

SUMMARY Cloud computing has become more and more popular nowadays since it possesses various conveniences such as pay as you go, dynamically deployment, and high efficiency. A numbers of cloud computing platforms are now in the market. Apache Hadoop, an open‐source platform, is one of these platforms which has been widely used by companies and organizations, because it is free for both research and production. From the perspective of service providers, it is better to see infrastructure running at the lowest possible power consumption and in the same time satisfying the QoS. From the viewpoint of the service clients, it is also the best situation that all functions they desire are running well at the lowest service cost. By putting ourselves in their shoes, in this paper, we propose the event trigger, which provides an automatic event recording mechanism. The event trigger applies the recorded parameters onto an easy‐understanding visual graph. By doing so, users will be able to adjust their deployment of hardware resource through a simple and straightforward understanding of their system performance records. Copyright © 2013 John Wiley & Sons, Ltd.

ABSTRACT The advance of computer network technologies such as IEEE 802.11 wireless local area network has made it possible for users to connect to Internet almost anywhere. A mobile node (MN) is likely to move between different base stations while running applications. The IETF has defined the Mobile IP (MIP) to allow MNs to maintain their communication uninterrupted while roaming across different IP subnets. However, the mechanisms defined in MIP may cause undesired connection disruptions or packet losses, which will significantly degrade the quality of real‐time applications. It is an important and challenging issue to support seamless handoff management. To achieve seamless handoff, we propose a unified scheme to address application quality degradation. Our main contribution is the concept and implementation of utilising buffering and resending method to eliminate the packet losses while keeping the end‐to‐end delay of real‐time traffic flow in an acceptable value. The NS‐2 simulation results show that our proposed scheme can significantly maintain application quality during layer‐2 and ‐3 handoffs. Copyright © 2011 John Wiley & Sons, Ltd.

In this research, we propose a performance estimation model based on the queuing theorem including execution time and network transmission delay. With the evaluation, the proposed delay model enables a cloud system to perform resource allocation for cloud applications with lower delay and the lowest cost. Both the numerical analyses and simulation results clearly show the enough evidences to validate the proposed model. The findings are also in favor of the applicability of the proposed model for HPC (High-Performance Computing) applications in a distributed computing environment such as cloud systems.

Abstract This paper proposes a self‐stabilizing distributed algorithm for deploying mobile nodes with loaded energy to the stationary nodes by considering the energy those stationary nodes need. The goal is to deploy mobile nodes to appropriate locations for energy supplements such that the network lifetime can be extended. The problem of maximizing the lifetime is NP‐hard. Therefore, it is unrealistic to search for an optimal solution in sensor networks. In this paper, we design several simple rules for mobile nodes and stationary nodes separately in order to find a feasible solution. Simple rules are especially suitable and necessary for low computability sensor networks. Our algorithm is simple and distributed. We prove that our method is stable and has good performance. Simulations show its efficiency too. Copyright © 2010 John Wiley & Sons, Ltd.

ZigBee networks based on the IEEE 802.15.4 standard are designed for wireless sensor and control networks with low cost, low power consumption, and low data rate. To join in a ZigBee network with the tree topology, the hardware requirement of a device is simple and low threshold. However, a device may become an isolated node due to constraints of configuration parameters in the ZigBee network. To decrease isolated nodes, we propose an approach called Enhanced Connectivity Scheme for the ZigBee network. This scheme can efficiently reconstruct parts of the network to let more devices join and hence increase the join ratio. Our method can efficiently improve the connectivity of ZigBee networks. The experimental results show that Enhanced Connectivity Scheme has high performance. We provide an innovative solution to increase connectivity of ZigBee networks.

In recent years, mobile ad hoc network (MANET) has gained a lot of attention because of its self-organising and infrastructure-free characteristics. Unlike the traditional wireless networks, each node in MANET can act as a router to receive and forward packets. All nodes can randomly move around, leave the network or switch off. Hence, broadcasting has been widely used in diffusing data, routing or topology information in MANET. Unfortunately, MANET may be filled with a large number of redundant broadcasting packets. Furthermore, in order to transmit the broadcasting packets, each mobile node (MN) competes for the limited radio channels. Thus, packet collision is serious. All of these aforementioned conditions are called the ‘Broadcast Storm Problem’. Not only does it occupy the network bandwidth but it also consumes the battery of MNs. In this study, the authors propose an algorithm that is different from previous works to solve the Broadcast Storm Problem. The algorithm is suitable for a dynamic MANET environment.

When human culture advances, current problems in science and engineering become more complicated and need more computing power to tackle and analyze. A supercomputer is not the only choice for complex problems any more as a result of the speed-up of personal computers and networks. Grid technology, which connects a number of personal computers with high speed networks, can achieve the same computing power as a supercomputer does, also with a lower cost. However, grid is a heterogeneous system. Scheduling independent tasks on it is more complicated. In order to utilize the power of grid completely, we need an efficient job scheduling algorithm to assign jobs to resources in a grid. In this paper, we propose an Adaptive Scoring Job Scheduling algorithm (ASJS) for the grid environment. Compared to other methods, it can decrease the completion time of all submitted jobs, which may compose of computing intensive jobs and data-intensive jobs.

Data grids deal with a huge amount of data regularly. It is a fundamental challenge to ensure efficient accesses to such widely distributed data sets. Creating replicas to a suitable site by data replication strategy can increase the system performance. It shortens the data access time and reduces bandwidth consumption. In this paper, a dynamic data replication mechanism is proposed, which is called Latest Access Largest Weight (LALW). LALW selects a popular file for replication and calculates a suitable number of copies and grid sites for replication. By setting a different weight for each data access record, the importance of each record is differentiated. The data access records in the nearer past have higher weight. It indicates that these records have higher value of references. In other words, the data access records in the long past have lower reference values. A Grid simulator OptorSim is used to evaluate the performance of this dynamic replication strategy. The simulation results show that LAHW successfully increases the effective network usage. It means that the LALW replication strategy can find out a popular file and replicates it to a suitable site.

This paper proposes a communication scheme for collaboration groups to track objects in a sensor network. We divide the sensor nodes into clusters. Each cluster is a geographical hexagon area. We design a data transmission route for cluster communication. Using the hexagonal clustering idea, we can save power in collaboration group for tracking objects. Our protocol considers how to switch quickly among different clusters. We optimize the size of cluster area to minimize energy consumption. The simulation results show better performance than other group communication schemes.

In data grids, replication is a critical technology aiming at lowering the access delay as well as saving network bandwidth by duplicating original data in a distributed manner. For data-intensive applications with read/write files, replica consistency is an important issue. In this paper, we propose a novel replica consistency decision model with high adaptability and flexibility using the naive Bayesian classifier in order to improve the system performance in data grids. A system prototype has been implemented. The experimental results also prove the excellence of the proposed model.

Multi-constrained quality-of-service (QoS) routing is used to find routes in a network to satisfy multiple independent QoS constraints. This problem is considered to be NP-complete, and most existing QoS routing algorithms are based on maintaining a global network state at every node. A multi-constrained, flooding-limited, QoS routing method to deal with limited available resources and minimum computation in a dynamic environment is proposed. The solution is based on decomposition of a routing area and a restriction in the exchange of routing information. It reduces the size of the control messages, restricts the amount of routing information, minimises the overhead from the flooding of control traffic and decreases the complexity of path selection. It is also proved that the flooding-limited-path heuristic can achieve very high performance by maintaining entries in each node, which indicates that the performance of the limited-path heuristic is not sensitive to the number of constraints. Simulation results show that this protocol provides better performance than other protocols, especially with regards to end-to-end delay, throughput and packet loss.

Grid computing is a new research subject. The computing power and storage space of grids is collected from heterogeneous or homogeneous resources in order to support complicated computing problems. Job scheduling in computing grid is a very important problem. Current scientific applications become more complex and need huge computing power and storage space. It may take a very long time to complete a complicated job. However, to utilize grids, we need an efficient job scheduling algorithm to assign jobs to resources in grids. In this paper, we propose a Balanced Ant Colony Optimization (BACO) algorithm for job scheduling in the Grid environment. There are two schemes introduced in this paper regarding local and global pheromone update. The main contributions of our work are to balance the entire system load and minimize the makespan of a given set of jobs. Compared with the other proposed algorithms, BACO can outperform them according to the experimental results.

Sensing coverage is an important issue in wireless mobile sensor networks. The strategy of how to deploy sensor nodes in an environment, especially in unknown large environment, will affect the utility of the network just like the quality of communication. We present an efficient method for sensor deployment assuming that global information is not available. Our algorithm (Self-Deployment by Density Control, SDDC), uses density control by each node to deploy sensor nodes concurrently. We also make nodes to form clusters to achieve area density balance. The characteristics in SDDC are concurrent multi-sensors moving, distributed operation, localized calculation, and self-deployment. Simulations show the good performances compared to the incremental self-deployment algorithm.

In many scenarios, sensor nodes have to rely on a limited supply of energy (using batteries). To support long lifetime of wireless sensor networks (WSN), an energy-efficient way of operation of the WSN is necessary. In this paper, we propose a new controlled layer deployment (CLD) routing protocol to guarantee coverage and energy efficiency on a sensor network. CLD outperforms PEAS (probing environment and adaptive sleeping) and the TTDD (two-tier data dissemination) protocols in that it can guarantee full area coverage and connection. It can also solve the "cascading problem" which reduces the whole network lifetime. Finally, we show the results of the simulation to prove that the new protocol can use fewer sensor nodes for coverage and increase the lifetime as compared to the PEAS protocol.

This paper studies link layer throughput maximisation for mobile ad hoc network routing algorithms. We analyse the transmission rates and take into account the interference effects to propose a theoretical model of throughput maximisation called Throughput Aware Link Selection (TALS). TALS can easily be infused into other routing protocols. Simulations show performances increases when compared with other methods. The results demonstrate that TALS helps to increase network throughput.

Mobility support in Internet Protocol version 6 (IPv6) is a de facto standard for allowing nodes to remain connected while moving around in the IPv6 networks. To provide better handoff latency and performance, numerous optimisation techniques were developed. Some of them are single-layer optimisation such as the Hierarchical Mobile IPv6 architecture, which aims at reducing the registration time in network layer. Others are cross-layer optimisation such as the Fast Handover mechanism, which tries to reduce the address resolution time in network layer based on the data-link layer detection. Most of these techniques are focused on data-link and network layer optimisation. The authors propose a cross-layer mechanism, which uses the standard binding update packet in Mobile IPv6 handoff to enhance the overall transmission control protocol performance in transmission. The theoretical analysis and simulations show promising performance enhancements.

Abstract Recently, there has been an increasing interest in mobile ad hoc networks. In a mobile ad hoc network, each mobile node can freely move around and the network is dynamically constructed by collections of mobile nodes without using any existing network infrastructure. Compared to static networks, it faces many problems such as the inefficiency of routing algorithms. Also, the number of control packets in any routing algorithm increases as the mobile speed or the number of mobile nodes increases. Most of the current routing protocols in ad hoc networks broadcast the control packets to the entire network. Therefore, by reducing the number of control packets, the efficiency of the network routing will be improved. If we know where the destination is, we can beam our search toward that direction. However, without using global positioning systems, how can we do this? Define the range nodes as the 1‐hop or 2‐hop neighbors of the destination node. In this paper, we propose using the range nodes to direct our searches for the destination. It can be combined with the existing routing protocols to reduce the control overhead. We show through simulations that AODV and DSR combined with the range node method outperforms the original AODV and DSR routing protocols in terms of control packets overhead. We also show that the delay introduced in find range nodes is insignificant. Copyright © 2006 John Wiley & Sons, Ltd.

In recent years, there has been a growing interest in wireless sensor networks. One of the major issues in wireless sensor network is developing an energy-efficient routing protocol. Since the sensor nodes have limited available power, energy conservation is a critical issue in wireless sensor network for nodes and network life. Most of the existing routing protocols for sensor networks don't turn off the radio frequency completely. They speed up the energy consumption. LEACH (low energy adaptive clustering hierarchy) is a clustering-based protocol that non-cluster-head nodes will turn off their RF completely until their pre-allocated time slot. However, LEACH has a drawback that the cluster is not evenly distributed due to its randomized rotation of local cluster-head. In this paper, we propose a MECH (maximum energy cluster head) routing protocol. It has self-configuration and hierarchical tree routing properties. MECH improves LEACH in several aspects. MECH constructs clusters based on radio range and the number of cluster members. The cluster topology in the network is distributed more equally, through our cluster constructing. We also propose a hierarchical tree routing method that reduces the distance of cluster-head to the base station.

Abstract Bluetooth is one of the cable‐replacement technologies. It uses short‐range radio links to replace connecting cables. Bluetooth enables portable devices to form short‐range wireless ad hoc networks. A set of Bluetooth devices sharing a common channel can form a personal area network called a piconet. Several piconets can also be interconnected to establish a scatternet. Zaruba, Basaghi and Chlamtac proposed a mechanism for forming a distributed scatternet called the Bluetree. The algorithm is based on selecting an arbitrary node serving as the Blueroot. The Blueroot initiates the construction of the Bluetree. Though the algorithm is very simple, there are some weak points. For example, being a tree limits its routing choices. There are also the problems of overloading on the Blueroot and the many master/slave bridges on any routing path. In this paper, we will improve the weaknesses of Bluetree by eliminating the bottleneck in the Blueroot and by reducing the number of bridges to half for almost any path. We call the new algorithm Bluegon since polygons (cycles) will be formed in the scatternet. Simulation results indicate the efficiencies of our algorithm. Copyright © 2006 John Wiley & Sons, Ltd.

Abstract In this paper, we propose a new fast handoff routing method, called fast handoff using prerouting, for mobile IPv6. The new routing method will improve the packet delay and save the bandwidth during handoff. It routes the packet to the destination before the mobile node finishes its route update to the corresponding node (CN). It can also save the bandwidth wasted in tunneling during route update to CN. Special agents attached to the access routers and border routers are proposed to help prerouting. The proposed fast handoff combines the benefits of cellular systems and data communication systems. The agent residing in the routers will act as an MSC in a cellular system and it takes care of mobile nodes in its wireless LAN. Simulation results demonstrate its efficiency compared to previous schemes. Copyright © 2006 John Wiley & Sons, Ltd.

In this paper, we present a method for improving the quality of service (QoS) in multimedia wireless systems based on prioritization of handover requests. A strategy called signal strength for multimedia communications (SSMC) is proposed. In this strategy, we calculate a handoff priority for every multimedia service using three values: the static priority value, the degradation rate of the received signal strength (/spl Delta/RSS), and the RSS level itself. Then, each handoff request is queued and handled according to its priority value. We present the detailed algorithm and analyze its performance on a 25-cell network. Then, its performance is compared with other methods by simulations. The results indicate our method can effectively reduce the handoff call dropping probability compared to nonpriority schemes.

Abstract In ad hoc wireless networks, the high mobility of hosts is usually a major reason for link failures. The general ‘shortest path’ based routing protocols may not lead to stable routes. In this paper, we propose a mobility assessment on‐demand (MAOD) routing protocol to select a stable route in order to enhance system throughput and performance. An error count parameter is used to judge whether a host is highly mobile. The proposed MAOD routing protocol is an on‐demand routing protocol similar to dynamic source routing (DSR). The difference between MAOD and DSR is in the path selection method. Because MAOD takes the mobility of hosts into consideration, it will select a more stable and reliable path than DSR. In comparison, DSR only considers whether this route is a shortest path or not. Finally, the system performance is analyzed by using the global mobile simulation (GloMoSim) simulator. We can observe that MAOD routing protocol outperforms DSR routing protocol especially in the high mobility environment. Copyright © 2004 John Wiley & Sons, Ltd.

In this paper, we propose a new multicast routing protocol, named weight-based clustering multicast protocol (WCMP), for mobile ad hoc networks. The goal of this work is to improve multicasting performance in ad hoc networks by efficient use of the available knowledge of the networks.

Abstract In a code division multiple access (CDMA) wireless communication system, each mobile handset must be power controlled such that the power received at the base station is roughly the same. Otherwise, the interferences between mobile handsets will degrade the performance and increase the error rate. When a mobile handset uses channels from the neighbouring cells, it will raise its power to meet the threshold of signal strength. This will also increase the interference in the home cell. Therefore, we do not want a mobile handset to use channels from other cells blindly. In this paper, we propose an uplink channel assignment method based on the directed retry concept for CDMA cellular systems. The purpose is to achieve load balancing between neighbouring cells and at the same time controlling the interference levels at the base stations such that it will not affect the performance. Furthermore, priorities are given to handoff calls when assigning channels. Copyright © 2002 John Wiley & Sons, Ltd.

In ad hoc wireless networks, the high mobility of hosts is usually a major reason for link failures. The general "shortest path" based routing protocols may not lead to stable routes. In this paper, we propose a mobility assessment on-demand (MAOD) routing protocol to select a stable route in order to enhance system throughput and performance. An error count parameter is used to judge whether a host is highly mobile. The proposed MAOD routing protocol is an On-Demand routing protocol similar to DSR (Dynamic Source Routing). The difference between MAOD and DSR is in the path selection method. Because MAOD takes the mobility of hosts into consideration, it will select a more stable and reliable path than DSR. In comparison, DSR only considers whether this route is a shortest path or not. Finally, the system performance is analyzed by using the Global Mobile Simulation (GloMoSim) simulator. We can observe that MAOD routing protocol outperforms DSR routing protocol especially in the high mobility environment.

Broadcasting is an often seen operation in the wireless network environment. In an ad hoc wireless network, because of the mobility of each host, it is not an easy job for every mobile host to receive the broadcast message. Applications such as current time synchronisation, paging, finding the route to a particular destination, etc., all need to broadcast frequently. A simple broadcasting strategy is flooding. However, flooding leads to many redundant broadcasts and makes poor utilization of bandwidth. We try to improve the performance of broadcasting in an ad hoc wireless network. We propose several methods to reduce the redundancy of rebroadcasting the same message and increase the reachability.

The DQRUMA (distributed-queueing request update multiple access) protocol has been considered as an access protocol for the BAHAMA (broadband ad hoc wireless ATM local area network). However, it cannot support the service discipline of integrated multimedia traffic since it does not include any priority and access control policy. In this paper, we propose a nonpreemptive priority-based access control scheme for the DQRUMA protocol. Under such a scheme, modifying the CSMA/CA protocol in the contention period supports many levels of priorities such that user mobility (handoff) can be supported in BAHAMA. Besides, the proposed transmit-permission policy and adaptive bandwidth allocation scheme provide various QoS (quality-of-service) guarantees while maintaining high bandwidth utilization. Simulations show that it provides a good performance in ad hoc wireless ATM LAN environments.

Transmission control protocol/Internet protocol (TCP/IP) is the de facto standard of the networking world. It dynamically adjusts routing of packets to accommodate failures in channels and allows construction of very large networks with little central management. But IP packets are based on the datagram model and are not really suited to real-time traffic. In order to overcome the drawbacks, a new network technology, ATM, is proposed. ATM provides quality of service (QOS) guarantees for various classes of applications and in-order delivery of packets via connection oriented virtual circuits. Unfortunately, when ATM is to be internetworked with the existing network infrastructure, some special signaling, addressing and routing protocols are needed. IP over ATM is one of the methods proposed by IETF. It allows existing TCP/IP applications to run on ATM end-stations and ATM networks to interconnect with legacy LAN/WAN technologies. But the performance of TCP/IP over ATM leaves something to be desired. Partial packet discard (PPD) and early packet discard (EPD) are two schemes to improve its performance. This paper proposes a "selective packet retransmission" scheme for improving HTTP/TCP performance when transmitting through ATM networks. In selective packet retransmission, we take advantage of the property of humans' perception tolerance for errors to determine whether to retransmit a corrupted TCP segment or not. For lossable data, such as images, when an error occurs because of cell losses, it will not be retransmitted. The simulations show that, for the same buffer size and traffic load, selective packet retransmission performs better than PPD, EPD, and plain TCP over ATM.

This paper proposes a "selective packet retransmission" scheme for improving HTTP/TCP performance when transmitting through ATM networks. In selective packet retransmission, we utilize the property of human's perception tolerance for errors to determine whether to retransmit a corrupted TCP segment or not. For lossable data, such as image, when error occurs because of cell lost, it will not be retransmitted. The simulations show that, for the same buffer size and traffics load, selective packet retransmission results in higher throughput than PPD, EPD, and plain TCP over ATM.