Search

The development of the mobile market is not only long term evolution (LTE) but also leads to the next generation by adopting LTE software-defined network (SDN). The advantages of SDN are more flexible, manageable, programmable and less cost. SDN technology separates between the control and data plane so easy to handle the whole network with the application. The target issues on the core networks are traffic routing, core network sharing, and traffic management. Traffic management in the LTE core network is the critical functionality that handles mobility events to deliver reliable and low latency handover. An important topic for low latency is load balancing. This paper proposed a focus to reduce overload in packet core mobile defined network using a load balancing. The experimental results show that the proposed method can handle a heavy load problem on the serving gateway (SGW). After being triggered by load balancing, it can balance the traffic on all of the SGWs which has overload. The balanced SGWs can get high throughput and decrease latency of the network.

LEACH has major issues regarding the number of clusters formed. The fluctuation significantly number of clusters in each round destabilizes the wireless sensor network (WSN) architecture. In order to produce a better lifetime on the architecture of WSN, LEACH partition topology (LEACH-PT) is proposed in this paper. In LEACH-PT, cluster head (CH) is chosen by the base station (BS). It can guarantee the number of clusters formed is fixed on each round. In addition, this action will also minimize the burden of energy consumption at each node, resulting network lifetime better than LEACH. In addition, the distribution node is done evenly to the specific provisions than the existing random topology on LEACH. It is also a major focus on the LEACH-PT algorithm. The result of the simulation using network simulator 2 shows that LEACH-PT has significant better performance in term of nodes lifetime than that of LEACH.

Cloud security is an evolving sub-domain of computer and network security. Cloud platform utilizes third-party data centers model. An example of cloud platform as a service (PaaS) is Heroku. It supports several programming languages that are used for web application deployment model. Heroku is based on a managed container system, with integrated data services and a powerful ecosystem, for deploying and running modern apps. One essential issue in cloud computing is data security, which is handled using cryptography methods. A possible method to encrypt data is Advanced Encryption Standard (AES). In this paper, we implement Heroku as a cloud platform, then we implement AES for data security in Heroku. The performance evaluation shows that AES cryptography can be used for data security. Moreover, delay calculation of data encryption shows that larger size of data increases the data delay time for encrypting data.

Internet of Things (IoT) is the trend of future Internet, and wireless sensor network (WSN) is one of the core components of the IoT. WSN consists of a number of devices which can communicate to each other, to transfer control and status data. These devices are used in the sensing layer of IoT, and IEEE 802.15.4 is one of the major standards used in WSN. IEEE 802.15.4 can optionally use the superframe structure to regulate the transmission of data. The superframe includes active portion and inactive portion, and the active portion can be divided into contention access period (CAP) and contention free period (CFP). The contention free period (CFP) is used for applications that need time-critical and QoS requirements. CFP consists of one or more guaranteed time slot (GTS), and data fragmentation problem occurs frequently if the GTS is divided inappropriate. Furthermore, the beacon order and superframe order cannot adaptive adjustment according to the traffic type and network condition, resulting in performance decrease. In order to solve the above problems, we propose a priority-based algorithm for adaptive superframe adjustment and GTS allocation (PASAGA) for the superframe structure. PASAGA improve the goodput and delay for high priority data by dividing the GTS length from historical packet size and adjusting BO and SO according to network load. Simulation results show that the proposed algorithm outperforms the IEEE 802.15.4 standard in terms of goodput, delay and energy consumption for high priority data.

The challenges of CSMA/CA as following: first, when the device nodes detect the channel in busy condition, the device nodes have to increase the value of backoff exponent which cause range of blind backoff process also increase. Second, the blind backoff process will cause lower channel utilization and more energy consumptions. This article proposes a scheme to improve IEEE 802.15.4 medium access control, called adjustment delay scheme (ADES). This article also presents a comprehensive Markov chain analysis to predict the probability of successful transmission, network goodput, bandwidth utilization and total network energy consumption. The validity of the model analysis is proven by precisely matching the simulation experiments. ADES performs better than those of other algorithms in term of the probability of successful packet transmission, network goodput, bandwidth utilization as well as energy consumption in the networks

To study wireless network, a network simulator always is an important tool for researchers to evaluate their theories. If a selected simulator inherently has poor architecture, the maintenance, will become more difficult in the future. To increase the flexibility of a simulator's architecture, the use of design patterns as the norms of system architecture design is suggested in this paper. We propose a network simulator architecture, named as CCGns, which is a discrete-event virtual network simulator and follows the IEEE 802.16-2009 standard. The main contribution of CCGns is to propose five aspects: a scalable MAC messages management and processing architecture, an applicable for multi-hop relay network architecture, a two-stage minimum variance bandwidth allocation algorithm, a comparable compound factors-based common scheduler operating interface architecture, and an exchangeable frame structure architecture for WiMAX and LTE. In the aspect of expanding module function, we show the simulation results of using uniform, random, or round-robin scheduling to allocate bandwidth resource. We try to replace the WiMAX frame structure with LTE frame structure, and demonstrate the system performance of the relay network architecture for WiMAX and LTE protocol. We hope this study will benefit researchers who need to implement their network simulators.

Wireless sensor networks based on the IEEE 802.15.4 standard is able to carry out short-distance transmissions in low-rate and low-power wireless personal area networks. To access the channel, it uses the slotted carrier sense multiple access with collision avoidance (CSMA/CA) in the contention access period (CAP) under superframe structure with beacon frame broadcast to bound the duration of superframe. However, the beacon frame is transmitted periodically without CSMA/CA so that it could be collided continuously. This type of collision causes node lost synchronization and unable to join a network because the beacon frame cannot be normally received. This paper proposes a simple time shift scheme based on IEEE 802.15.4 to keep original superframe structure and distribute transmission of beacon frame over active period to avoid beacon frame collisions. We use a simple function to allocate beacon frame transmission in the active period. The simulation results show that the proposed scheme significantly reduces the beacon collision and lost synchronization rate, and it also improves the throughput.

A network simulator always is an important tool to observe and evaluate the study concept for wireless networks. Considering the restriction of the limited budget, the non-commercial open-source simulation software often becomes the top choice of academia. Since the natures of academic study are innovation and excellence, a simulator frequently encounters that the existing modular functions are inadequate and need to be appended or modified. If a selected simulator inherently has poor architecture, the maintenance, recondition, and expansion of functions will become more difficult and more time-consuming in the future, while it is difficult to understand and reuse by the successors. Therefore, how to select a most suitable simulator is an important issue. In order to make a simulator have flexible architecture and believable results, design patterns are proposed as the norms to design system architecture. To realize this idea, we surveyed six most used simulators, i.e., J-Sim, NS-2, NS-3, OMNet++, OPNET, and QualNet, to ponder their system architectures and design concepts from the source codes and the related literatures of the modular function expansion. We propose a network simulator architecture, named as CCGns, which is a discrete-event virtual network simulator and follows the IEEE 802.16-2009 standard. CCGns obeys the object-oriented design principles and is coded by the Java language. CCGns comprises eight packages for physical layer, medium access control layer, network layer, devices, topologies, events, scheduler, and reports, respectively. The main contribution includes three aspects which propose a scalable MAC messages management and the corresponding architecture, an applicable for multi-hop relay network topology architecture, and a two-stage minimum variance bandwidth allocation algorithm. To the best of our knowledge, this article is not the first one to apply the design patterns for the simulator architectures of wireless network, but we use more design patterns and types than the others and also provide the unified modeling language figures to explain the system architectures. We particularly focus on how the management procedure of control messages influences the time-related performance evaluation metrics, e.g., how the amount and processing time of different control messages affect throughput, packet delay, and packet drop ratio. By using mathematic calculation to verify the simulation results, the proposed system architecture has been proven to possess excellent fidelity.

Nowadays, the use of Electrocardiogram (ECG) as a detection tool of the condition of human heartbeat is still considered difficult. So, the idea of implementing this sensor is to enhance the quality of service and to minimize the cost of using and maintaining by determining the best way in implementing and monitoring ECG sensor. This research proposes a novel approach to observe the condition of human heartbeat using ECG sensor with e-Health sensor and Raspberry Pi, mini single-board computer with robust capability, which acts as central processing unit. Those hardware sets were assembled to collect ECG voltage signals in human body. The signals are transmitted into the device and the data are stored in MySQL database for long-term monitoring access. The experimental results show effectiveness of this approach as it is successfully fulfill the idea of Body Area Network (BAN).

In order to achieve the prioritized quality of service (QoS) guarantee, the IEEE 802.11e EDCAF (the enhanced distributed channel access function) provides the distinguished services by configuring the different QoS parameters to different access categories (ACs). An admission control scheme is needed to maximize the utilization of wireless channel. Most of papers study throughput improvement by solving the complicated multidimensional Markov-chain model. In this paper, we introduce a back-off model to study the transmission probability of the different arbitration interframe space number (AIFSN) and the minimum contention window size (CWmin). We propose an adaptive control scheme (ACS) to dynamically update AIFSN and CWmin based on the periodical monitoring of current channel status and QoS requirements to achieve the specific service differentiation at access points (AP). This paper provides an effective tuning mechanism for improving QoS in WLAN. Analytical and simulation results show that the proposed scheme outperforms the basic EDCAF in terms of throughput and service differentiation especially at high collision rate.

Wireless body area network (WBAN) is a term used to describe a network of sensor devices connected wirelessly for communication on, in and near the body to obtain physiological data from sensor devices. This paper explain the implementation of WBAN for monitoring body temperature, heart beat rate and oxygen saturation in blood. We develop the sensor reads physiological data to the desktop application, then will read the printout of the series and create a visual in the tables and graphs, as well as storing the data into a database and displayed via a website in the form of reports that can be accessed remotely. We analyze the data received from sensor nodes to server receiver with a variety of different distances 10, 20, 30, 40, and 50 meters. The experiment results show that the physiological data can be accessed through ZigBee wirelessly in short distance which suitable for WBAN.

Cognitive radio network is expected to use flexible radio frequency spectrum sharing techniques to achieve more efficient frequency spectrum usage. This article considers the spectrum sharing problem that one primary user (PU) can share its frequency spectrum by renting this spectrum to multiple secondary users (SUs). The pricing scheme is a key issue for spectrum sharing in cognitive radio network. We first propose a nonlinear one leader multiple followers (NLMF) sharing spectrum scheme as a multi-object optimization problem; the prices are offered by PU to SUs at the same time. This problem can be solved by using particle swarm optimization (PSO); SUs gradually and iteratively adjust their strategies respectively based on the observations on their opponents' previous strategies until Nash equilibrium is completed. We then present a general nonlinear bilevel one leader multiple followers (NBMF) optimization problem to further consider the revenue of the PU and a new optimal strategic pricing optimization technique which applies bilevel programming and swarm intelligence. A leader-follower game is formulated to obtain the stackelberg-nash equilibrium for spectrum sharing that considers not only revenue of a PU but also the SUs utility. The behaviors of the pricing model have been evaluated; and the performance results show that the proposed algorithm is well-performed to solve the spectrum sharing in a cognitive radio network.

To support the presentation requirements of distributed multimedia information, synchronization of multimedia objects must be achieved. To this end, system resource scheduling and resource reservation for object pre‐fetch, network bandwidth and buffer occupancy must be determined prior to the time the presentation is initiated. This paper proposes an object‐oriented model to handle the temporal relationship for all of the multimedia objects at the presentation platform and study the related problems of resource allocation. Synchronization of the composite media objects is achieved by ensuring that all objects presented in the upcoming “manageable” period must be ready for execution. To this end, the nature of overlap is first examined for various types of objects. The importance of critical overlap and critical point that are vital to synchronization is addressed and taken into account in this research. The concept of manageable presentation interval and the irreducible media group are also intro...

Cognitive radio network is expected to use flexible radio frequency spectrum sharing techniques for achieving more efficient frequency spectrum usage. In this article, we consider the spectrum sharing problem that one primary user (PU) can share its frequency spectrum by renting this spectrum to multiple secondary users (SUs). The pricing scheme is a key issue for spectrum sharing in cognitive radio network. We first propose a nonlinear one-leader–multiple-follower (NLMF) sharing spectrum scheme as a multi-object optimization problem; the prices are offered by PU to SUs at the same time. This problem can be solved using particle swarm optimization (PSO); SUs gradually and iteratively adjust their strategies respectively based on the observations on their opponents' previous strategies until Nash equilibrium is completed. We then present a general nonlinear bilevel one-leader-multiple-follower (NBMF) optimization problem to further consider the revenue of the PU and a new optimal strategic pricing optimization technique which applies bilevel programming and swarm intelligence. A leader-follower game is formulated to obtain the Stackelberg-Nash equilibrium for spectrum sharing that considers not only revenue of a PU but also the SUs utility. We develop a swarm particle algorithm to iteratively solve the problem defined in the NBMF decision model for searching the strategic pricing optimization. The behaviors of two pricing models have been evaluated, and the performance results show that the proposed algorithms perform well to solve the spectrum sharing in a cognitive radio network.

IEEE802.11s draft proposes a new medium access control function-mesh deterministic access (MDA), which is mainly used for single-channel wireless mesh local area network (LAN). In single-channel environment, collisions between control packets and data packets may occur very often. To reduce the hardware requirements in design, a mesh point only equips single transceiver to support multi-channel environment. To completely avoid the collision between control packets and data packets, the interval of the meshed delivery traffic indication message is first divided into contention period and data transmission period. To provide high performance and network capacity for wireless mesh LAN, this paper proposes a dynamic adjustable contention period (DACP) mechanism and adaptive backoff process (ABP) to improve the performance of the multi-channel MDA (MMDA). The theoretical analysis gives the upper limit of the throughput for DACP. The simulation experiments clearly show the results in multi-channel wireless mesh LAN environment that the proposed scheme performs better than MMDA and the original enhanced distributed channel access (EDCA) in throughput, average waiting time, and packet drop ratio.