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In this paper, we propose a new Medium Access Control (MAC) protocol for Wireless Sensor Networks (WSNs) called MMSMAC (Multi-Mode Sensor MAC protocol), which can operate and switch among three modes: synchronous, asynchronous, and hybrid, according to the application requirements. In the synchronous mode, MMSMAC organizes the sensor nodes under even and odd clusters. Each sensor node has its own...
In this paper, a distributed traffic-balancing routing protocol is proposed for multi-sink industrial wireless sensor networks that effectively distributes traffic from sources to sinks. Each node has a gradient field that is used to decide on a neighbor node to reach a sink. The node's gradient index contains (1) the distance cost from source to a respective sink, and (2) traffic information from...
A framework for the joint design of wireless network and controllers is proposed. Multiple control systems are considered where the sensor measurements are transmitted to the controller over the IEEE 802.15.4 protocol. The essential issues of wireless networked control systems (NCSs) are investigated to provide an abstraction of the wireless network for a co-design approach. We first present an analytical...
A multichannel scheduling based on an extension of modified largest weighted delay first (M-LWDF) scheduling is proposed for heterogeneous traffic. We consider the downlink of an orthogonal frequency division multiplexing (OFDM) system where the wireless channel and queue state information are taken into account to schedule delay-sensitive and ratesensitive traffic. We propose a logarithmic notion...
The propagation speed of an acoustic signal is much slower than the speed of a terrestrial radio signal due to the physical characteristics of an underwater acoustic channel. This large delay can impact the throughput of the channel. There is a very high delay variance which presents unique challenges to the designs of efficient protocols. The inconsistent delay renders many traditional communication...
It is difficult to provide QoS guarantees for streams in wireless network based on IEEE802.11 DCF because of limited bandwidth. Taking CBR traffic as example, we studied the traffic performance with different parameters in this paper. The results show that for an overloaded network, the traffic with longer packet size has greater throughput. Since the MAC layer performs the same competitive algorithm,...
Underwater acoustic sensor networks (UWASNs) is an emerging technology, comprising of sensor nodes and unattended automated vehicles (AUVs), all working in a collaboration to sense various phenomenon, process digital information, store processed data and communicate among each other and base stations. Acoustic propagation in water is characterized by high and variable delays, fading effect, Doppler...
In timing analysis attackers study the transmission pattern of different nodes in a network with the goal of extracting information about users, applications, or the structure of the network, even when the traffic is encrypted. Defeating timing analysis attacks requires expensive traffic mixing measures that equalize the transmission pattern at all nodes; such measures are especially expensive for...
Modern cellular networks commonly deploy rapid channel rate adaptation to vary the wireless capacity in response to channel conditions while maintaining a fixed target error rate (typically 1%). Although desirable in terms of throughput for inelastic applications that do not adapt to network conditions, a low fixed target error rate incurs the expense of significant power consumption, especially at...
The foray of wireless sensor networks into time-sensitive applications demands support for emergency services with guaranteed quality of service (QoS) bounds. We introduced CP-EDCA, a channel preemptive enhancement to the IEEE 802.11e EDCA standard, for guaranteed emergency medium access in distributed wireless environments. The performance results for emergency traffic depicted 50% uniform decrease...
The QoS requests of data traffic with lower priority in hotspot areas are not always satisfied in a traditional cellular wireless communication system. But on the other hand, about 60% of the channel slots allocated to a voice user is wasted due to the spurt of speech packets. In this paper, a cooperative strategy for transmitting data packets and speech spurt packets over the shared channel of voice...
The traffic adaptive 2-level active period control has been proposed for performance enhancement in cluster-based wireless sensor networks (WSNs) employing IEEE 802.15.4 medium access control (MAC) under temporal and geographical non-uniform traffic distribution. This paper proposes an adaptive backoff window control method for the traffic adaptive 2-level active period control. The proposed method...
In order to improve the performance of existing multicast congestion control mechanisms applied to wireless networks, in this paper, we propose an expert-control-based intelligent multicast congestion control mechanism for wireless networks, termed ECMCC. ECMCC detects the network congestion state according to network relative queuing delay and packet loss, feedbacks information to multicast source...
Convergecast is a communication structure for wireless sensor networks (WSN) in which data flow from multiple nodes into one node. We use a two-tier slotted Aloha model to analyze the throughput and average packet delay of a convergecast mode based on slotted Aloha. In our model each node has a buffer and we use equilibrium point analysis (EPA) approach to study the model. Rayleigh fading is assumed...
Wireless mesh networks (WMNs) have been proposed to provide rapid deployment and easy reconfiguration of wireless broadband communications. WMNs can interoperate with WiMAX, Wi-Fi, sensor, or cellular networks in the hybrid working environments to relay packets robustly among these heterogeneous networks and significantly extend the coverage of individual wireless access networks. Many recent studies...
In this paper, we formally introduce the novel concept of traffic-adaptive, flow-specific medium access control and show that it outperforms contention, non-contention and hybrid medium access schemes. A traffic-adaptive, flow-specific mechanism is proposed that utilizes flow-specific queue size statistics to select between medium access modes. A general model for traffic-adaptive, flow-specific medium...
Underwater sensor networks (UWSNs) have attracted a lot of attention recently. Since data in UWSNs are transmitted by acoustic signals, the characteristics of a UWSN are different from those of a terrestrial sensor network. In other words, the high propagation delay of acoustic signals in UWSNs causes spatial-temporal uncertainty, and makes transmission scheduling in UWSNs a challenging problem. Hence,...
Wireless sensor network (WSN) is made up of a number of sensor nodes and base stations. The ad hoc nature of sensor deployment produces unpredictable patterns of connectivity and varied node density. Consequently, uneven bandwidth provisioning will occur on the forwarding paths. As the data converge towards the same base station, congestion may occur at sensors that receive more data than its maximum...
Network capacity is a critical feature of wireless ad hoc and sensor networks. It is particularly challenging to determine network capacity when combined with other performance objectives such as timeliness. This paper investigates real-time capacity for event-driven data-gathering sensor networks with the unbalanced many-to-one traffic pattern. First, we compute the average allowable throughputs...
Access points in 802.11 wireless networks suffer from performance problems because of insufficient resources at layer 2 - the DCF (distributed control function) access method provides equal access probability to all devices in a wireless cell including the access point itself. Consequently, performance degrades and contention between uploads and downloads can lead to the familiar TCP unfairness problem...
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