The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Bih-hwang Lee - One of the best experts on this subject based on the ideXlab platform.
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analysis of superframe duration adjustment scheme for ieee 802 15 4 networks
International Conference on Ubiquitous and Future Networks, 2015Co-Authors: Bih-hwang Lee, Eppy Yundra, Udin Harun Al M RasyidAbstract:The challenges of the IEEE 802.15.4 beacon-enable mode are how to improve throughput and bandwidth utilization in contention access period and contention free period, respectively. This article proposes a scheme to improve IEEE 802.15.4 medium access control, called superframe duration adjustment scheme (SUDAS). SUDAS is expected to effectively allocate guaranteed time slot to the requested devices, it adjusts the length of the slot in superframe duration based on the length of the packet data. This article also presents a comprehensive Markov chain analysis of IEEE 802.15.4, especially for star network, to predict the probability of successful transmission, average bandwidth utilization as well as total network energy consumption. The analytical model and simulation experiments show that the performance of SUDAS is better than that of IEEE 802.15.4 standard in term of the probability of successful packet transmission, average bandwidth utilization and total energy consumption.
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Analysis of superframe adjustment and beacon transmission for IEEE 802.15.4 cluster tree networks
EURASIP Journal on Wireless Communications and Networking, 2012Co-Authors: Bih-hwang Lee, Muhammad Udin Harun Al RasyidAbstract:Wireless sensor networks based on the IEEE 802.15.4 standard are able to achieve low-power transmissions in the low-rate and short-distance wireless personal area network (PAN). A cluster tree network consists of several clusters; each cluster has a coordinator, known as cluster coordinator, and several device nodes. In the cluster tree topology of IEEE 802.15.4, a PAN coordinator periodically transmits beacon frames to its coordinator nodes as well as a coordinator node periodically transmit beacon frames to their device nodes. The main challenge in the cluster tree network is the collisions between beacons or even between beacon and data frames, which degrades the network performance. In order to decrease collisions, this article proposes the superframe adjustment and beacon transmission scheme (SABTS) by assigning the accurate values of beacon order and superframe order for the PAN coordinator, cluster coordinators, and device nodes, and deciding the precise time for the beacon transmission of PAN and coordinator nodes. A Markov chain model for the cluster tree network is developed with taking into account packet retransmission, acknowledgement, and defer transmission. Both analytical and simulation results show that SABTS performs better than IEEE 802.15.4 standard in terms of the probability of successful transmission, network goodput, and energy consumption.
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study on a dynamic superframe adjustment algorithm for ieee 802 15 4 lr wpan
Vehicular Technology Conference, 2010Co-Authors: Bih-hwang LeeAbstract:IEEE 802.15.4 can optionally use the superframe structure for data transmission. However, the duty cycle of the superframe structure cannot be dynamically adjusted according to the situation of the entire network. Thus, when the traffic load of the network is high, the insufficient active periods will decrease the transmission opportunities of devices and increase the collision probability. In order to solve this problem, we propose the dynamic superframe adjustment algorithm (DSAA) to dynamically adjust the duty cycle of the superframe according to the channel opportunity and collision ratio observed by the coordinator. Simulation results show that the proposed algorithm outperforms the IEEE 802.15.4 standard and ECAP in terms of goodput, delay and power consumption.
Shairmina Shafi - One of the best experts on this subject based on the ideXlab platform.
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performance of ieee 802 15 4 beacon enabled pan with uplink transmissions in non saturation mode access delay for finite buffers
Broadband Communications Networks and Systems, 2004Co-Authors: Jelena Misic, Vojislav B Misic, Shairmina ShafiAbstract:In this work, we derive the probability distribution of access delay and calculate throughput of a personal area network operating under the IEEE standard 802.15.4 in the beacon enabled mode. We model the network using the theory of discrete time Markov chains and M/G/1/K queues. The model considers acknowledged uplink transmission in non-saturation mode, and includes the impact of different parameters such as packet arrival rate, number of stations, the finite size of individual node buffers, packet size, and inactive period between the beacons. Our model also captures the problem of congestion at the beginning of the superframe due to multiple transmissions delayed from the previous superframe. The results show that average access delays, even for small buffer sizes, may be quite high if the throughput exceeds 50%, which can seriously affect applications with delay bounds. Values of throughput larger than 50% can be achieved at the expense of larger buffer sizes, which imposes implementation problems on devices with small memory resources.
Jelena Misic - One of the best experts on this subject based on the ideXlab platform.
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access delay for nodes with finite buffers in ieee 802 15 4 beacon enabled pan with uplink transmissions
Computer Communications, 2005Co-Authors: Jelena Misic, Vojislav B MisicAbstract:In this work we analyze the performance of a personal area network operating under the IEEE Standard 802.15.4 in the beacon enabled mode, and derive the probability distribution of packet access delay and calculate the throughput. We assume that the network is operating in non-saturation mode and that the nodes have finite buffers. We model the operation of the PAN using the theory of discrete time Markov chains and M/G/1/K queues. The model considers acknowledged uplink transmission and includes the impact of different parameters such as packet arrival rate, number of stations, station's buffer size, packet size, and inactive period between the beacons. The model also captures the problem of congestion at the beginning of the superframe due to multiple transmissions being delayed from the previous superframe, and we propose a correction to the standard in order to avoid this problem. In order to achieve acceptable access delays and small blocking probability at the buffer (which has to be small), PAN must be operated at throughput less than 50%, which can be achieved by restricting the number of the nodes in the PAN, or by reducing the packet arrival rates at the nodes.
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performance of ieee 802 15 4 beacon enabled pan with uplink transmissions in non saturation mode access delay for finite buffers
Broadband Communications Networks and Systems, 2004Co-Authors: Jelena Misic, Vojislav B Misic, Shairmina ShafiAbstract:In this work, we derive the probability distribution of access delay and calculate throughput of a personal area network operating under the IEEE standard 802.15.4 in the beacon enabled mode. We model the network using the theory of discrete time Markov chains and M/G/1/K queues. The model considers acknowledged uplink transmission in non-saturation mode, and includes the impact of different parameters such as packet arrival rate, number of stations, the finite size of individual node buffers, packet size, and inactive period between the beacons. Our model also captures the problem of congestion at the beginning of the superframe due to multiple transmissions delayed from the previous superframe. The results show that average access delays, even for small buffer sizes, may be quite high if the throughput exceeds 50%, which can seriously affect applications with delay bounds. Values of throughput larger than 50% can be achieved at the expense of larger buffer sizes, which imposes implementation problems on devices with small memory resources.
Gang Uk Hwang - One of the best experts on this subject based on the ideXlab platform.
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enhanced markov chain model and throughput analysis of the slotted csma ca for ieee 802 15 4 under unsaturated traffic conditions
IEEE Transactions on Vehicular Technology, 2009Co-Authors: Chang Yong Jung, Ho Young Hwang, Dan Keun Sung, Gang Uk HwangAbstract:In this paper, we propose an analytical Markov chain model of the slotted carrier-sense multiple-access/collision-avoidance (CSMA/CA) protocol for IEEE 802.15.4 under unsaturated traffic conditions. Our proposed Markov chain model reflects the characteristics of the IEEE 802.15.4 medium-access control (MAC) protocol, such as a superframe structure, acknowledgements, and retransmissions with and without limit. We evaluate the throughput performance of the slotted CSMA/CA and verify the analytical model using simulation results.
Hyogon Kim - One of the best experts on this subject based on the ideXlab platform.
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data fragmentation scheme in ieee 802 15 4 wireless sensor networks
Vehicular Technology Conference, 2007Co-Authors: Jongwon Yoon, Hyogon KimAbstract:The IEEE 802.15.4 medium access control (MAC) protocol is designed for low data rate, short distance and low power communication applications such as wireless sensor networks (WSN). However, in the standard 802.15.4 MAC, if the remaining number of backoff periods in the current superframe are not enough to complete data transmission procedure, the sensor nodes hold the transmission until the next superframe. When two or more sensor nodes hold data transmission and restart the transmission procedure simultaneously in the next superframe, it causes a collision of data packets and waste of the channel utilization. Therefore, the MAC design is inadequate to deal with high contention environments such as densely deployed sensor networks. In this paper, we propose a data fragmentation scheme to increase channel utilization and avoid inevitable collision. Our proposed scheme outperforms the standard IEEE 802.15.4 MAC in terms of collision probability and aggregate throughput. The proposed scheme is easily adapted to the standard IEEE 802.15.4 MAC without any additional message types
