Catálogo de publicaciones - libros

This paper proposes EL-MAC, a contention-based medium access control (MAC) protocol, which is efficient and low-latency for the wireless sensor network (WSN). EL-MAC introduces duty-cycle and virtual cluster scheme within the framework of S-MAC to reduce energy consumption and to self-organize network. Besides, Inspired by D-MAC, the scheme of data forwarding chain (DFC) is proposed for reducing the latency in multi-hop transmission. The experiment of simulation shows that EL-MAC has lower latency and higher throughput with comparative energy consumption on different traffic load condition than S-MAC.

Power-efficiency and transmission delay are critical for periodical data gathering applications in wireless sensor networks. This paper presents a scalable power-efficient data gathering protocol with delay guaranty (PDGPDG) for wireless sensor networks. The protocol attempts to balance the energy consumption and transmission delay by dividing the entire network into clusters and then organizing clusters as sub-chains. The parallel transmission among different clusters minimizes the delay and routing data along near optimal sub-chain in the clusters reduces the total energy dissipation. PDGPDG is efficient in the ways that it prolongs the lifetime of network, as well as it takes much lower time to finish a transmission round. Simulation results show that it demonstrates about 200% better performance than that of LEACH in terms of network lifetime and improves the × metric by a factor of 2~6 compared to PEGASIS.

Data rate selection for IEEE 802.11-based wireless networks is not specified in the Specification. The problem of determining an appropriate data rate for the sender to send DATA frames and to adapt to changing channel conditions is referred to as . We propose DRA (differential rate adaptation), a rate adaptation scheme for IEEE 802.11 networks. It enables a high network throughput by adaptively tuning the data transmission rate according to the channel conditions. It is responsive to link quality changes and has little implementation overhead. Our experiments indicate that DRA yields a throughput improvement of about 20% to 25% compared to previous work.

Mobile multicast is a research hotspot and can provide many applications. Some schemes have been proposed to support the mobile subscriber, but most of them study the construction algorithm of dynamic multicast delivery structure and use the analysis and simulation to evaluate the performance, little concern on the multicast disruption time and protocol cost. In this paper, we propose a Multicast Listener Discovery (MLD) Proxy based Fast Multicast protocol for Mobile IPv6 (MP-FMIPv6), and implement simplified MLD proxy function on Home Agent (HA) and extend MLD host part function on MN. The analytical results show that MLD proxy based fast multicast can reduce multicast disruption time and cost. To evaluate the performance of proposed scheme in real applications, we setup a test-bed and compare it with Bi-directional Tunneling (BT) and Remote Subscription (RS) methods. The experiment results show that the proposed scheme nearly improves the multicast disruption time by 2.4 times and 3.66 times, and saves the cost about 19.1% and 57.4%, respectively.

This paper introduces a protocol for network-based localized mobility management solution, and develops an analytic model for the performance analysis based on one-dimensional random walk of mobile node. Based on the analytic models, the location update cost and the packet delivery cost are formulated. Then, the impacts of average cell residence time and the number of mobile nodes in a cell on the total cost are analyzed, respectively. In addition, the variation of the total cost is studied as the session-to-mobility ratio is changed and the optimal local mobility domain size to minimize the total cost is also investigated. The analysis results indicate that the session-to-mobility ratio and the local mobility domain size are critical performance factors in order to minimize the total cost.

Leading MAC protocols developed for duty-cycled WSNs such as B-MAC employ a long preamble and channel sampling. The long preamble introduces excess latency at each hop and results in excess energy consumption at non-target receivers in ultra low-duty cycled WSNs. In this paper we propose AS-MAC (Asynchronous Sensor MAC), a low power MAC protocol for wireless sensor networks (WSNs). AS-MAC solves these problems by employing a series of preload approach that retains the advantages of low power listening and independent channel sampling schedule. The preload massage includes a destination address and a remaining time until data transmission. Moreover AS-MAC offers an additional advantage such as flexible duty cycle as data rate varies. We demonstrate that AS-MAC is better performance than B-MAC through analysis and evaluation.

In wireless sensor networks (WSNs), congestion may occur when sensor nodes are densely distributed and/or burst a mass of data flows, the congestion tends to cause packet loss, which sequentially causes lower throughput and wastes energy. To address this challenge this paper proposes a new congestion control scheme, Phase-divided TCP (PTCP), for wireless sensor networks. It controls the congestion through phase-divided adjusting of the growth rate of the TCP window in the slow-start. Our simulation results demonstrate that the proposed scheme can dramatically resolve congestion control problem, and improve TCP performance of wireless sensor networks.

In this paper, we present a low latency media access control scheme which we call LLMAC (Low Latency MAC) for event-driven wireless sensor networks (WSN). In this kind of WSN, sensors do not regularly send data to the sink. They send a burst data only when there is an event in the monitoring area. It takes time for this burst data to arrive to the sink. Normally, these events are critical and we hope to obtain the information on the event in the shortest delay. Hence, the latency is considered to be a crucial requirement in event-driven WSN contrary to the traditional wireless networks where the fairness is the most important requirement. Our proposal LLMAC makes a trade-off between fairness and latency in order to offer a shorter latency transmission when certain events happen. The performance evaluation shows that our proposal reduces the latency in comparison to existing MAC protocols.

Flooding in wireless ad hoc networks is a fundamental and critical operation in supporting various applications and protocols. However, the traditional flooding scheme generates excessive redundant packet retransmissions, causing contention, packet collisions and ultimately wasting precious limited bandwidth and energy. In this paper, we propose an efficient flooding protocol called , which minimizes the flooding traffic by leveraging location information of 1-hop neighbor nodes. Our scheme works as if there were existing a hexagonal grid in the network field to guide the flooding procedure, only the vertex nodes which are located at or nearest to the vertices of the grid should be nominated to forward the message. We also provide a distributed algorithm for finding the vertex nodes. Simulation results show that our scheme is so efficient that it is almost able to reduce the number of forward nodes to the lower bound.

A typical scenarios was considered , in which an event, such as a mobile sink arriving to collect data via the wireless sensor network, initiates the collection of one packet of data from each node in the surrounding cluster. The node requesting the beacon synchronizes its time clock and purpose to the cluster and assumes the role of clusterhead. All nodes covers an area with a radius of several hundred meters, to within a few microseconds. We exploit this ability to extend the Contension Windows to improve retransmission algorithms in Zigbee MAC protocols. The result is a retransmission algorithm that uses a Extended Shared Contention Window (ESCW) that is easy to implement and results in fewer collisions than retransmission algorithms that use Binary-Exponential-Backoff (BEB). We show via numerical and simulation results that an ESCW-based Zigbee protocol performs significantly better – in terms of energy usage, throughput, and the time to complete the data collection task – than standard Zigbee (IEEE802.15.4).