Operation

For the correct operation of the SMACS protocol, the following assumptions are made. 1. Nodes are able to tune the carrier frequency to different bands. It is assumed that the number of available bands is relatively large. 2. Nodes are randomly deployed. After deployment, each node wakes up at some random time according to a certain distribution. 3. The network is assumed to consist primarily of stationary nodes, with few mobile nodes. Each node assigns links to its neighbors immediately after...

Energy Efficient Network Layer Protocols

The network layer in WSNs is responsible for data delivery from source to destination via well-selected routes 50, 89 . Due to the unique characteristics of WSNs, many of the network layer protocols designed for conventional ad hoc networks may not fit with the requirements of WSNs. The following principles must be considered in WSN network layer protocols Energy efficiency is always a dominant consideration. Routing is often data centric. Data aggregation fusion is desirable, but only useful...

Experimental Results

LEDES and MUSCLES were first evaluated with several randomly generated task sets with varying utilizations. The task sets consist of six tasks with varying hyperperiods and randomly generated device-usage lists. Because jobs may be preempted, each preempted slice of a job is considered as two jobs with identical device-usage lists. As a result, the number of jobs listed in each task set in Table 29.4 is an approximation. Each task in the task set uses one or more out of three I O devices whose...

Protocol Suite for Sensor Networks

Communication protocols in sensor networks are the fundamental cornerstone that glues distributed applications together. The deeply embedded nature of sensor networks presents some of the most interesting challenges in the design of their communication protocols. New research topics span all protocol stack layers, primarily motivated by a tighter interaction between the network and its physical environment. At the MAC layer, new protocols are needed that enforce message priorities consistently...

Concluding Remarks

Wireless sensor networks have numerous exciting applications in virtually all fields of science and engineering, including health care, industry, military, security, environmental science, geology, agriculture, and social studies. In particular, the combination with macroscopic or MEMS-based actuators is intriguing because it permits manipulation of the environment in an unprecedented manner. Researchers and operators currently face a number of critical issues that need be resolved before these...

Wireless SNs as Embedded Systems

The architecture of wireless SNs at the network level is briefly surveyed in this section. For the networking of the wireless devices and appliances, several communication schemes have been proposed, such as satellite, WLAN, cellular, and ad hoc multihop architectures 25, 26, 48, 49, 58 . Based on the different architectures, the communication between the nodes can be all low power (ranges in meters), high power (ranges in megameters), or medium power (ranges in kilometers). For example,...

Communication Mode Based Sensor Network Classification

With respect to the communication mechanism adopted, four basic architectures of sensor networks exist direct connected, flat ad hoc, peer-to-peer multihop, and cluster-based multihop, as shown in Figure 15.3. Because the number of sensor nodes is usually large and the transmit range of sensor nodes may be limited due to the battery capacity limitations, in general it is cost inefficient and, in many cases, impossible, for each small sensor to communicate directly with the collector. Thus, the...

Real Time Distance Aware Scheduling

Message communication in sensor networks must occur in bounded time for example, to prevent delivery of stale data on the status of detected events or intruders. In general, a sensor network may simultaneously carry multiple messages of different urgency communicated among destinations that are different distances apart. The network has the responsibility of ordering these messages on the communication medium in a way that respects time and distance constraints. A protocol that achieves this...

Technical Challenges

Populating the world with networks of sensors requires a fundamental understanding of techniques for connecting and managing sensor nodes with a communication network in scalable and resource-efficient ways. Clearly, sensor networks belong to the class of ad hoc networks, but they have specific characteristics that are not present in general ad hoc networks. Ad hoc and sensor networks share a number of challenges such as energy constraints and routing. On the other hand, general ad hoc networks...

Hardware

At the hardware level, components can be divided into two groups. The first consists of a computation engine, storage subsystem, and power supply infrastructure that are very reliable. Exceptionally reliable systems are available that incorporate sophisticated fault tolerance techniques even off-the-shelf microprocessors and DSP processors and controllers are very reliable devices with very low rates of malfunctioning. At least three main reasons indicate why this does not necessarily imply...

Data Funneling

Although energy-aware routing tries to route data packets, avoiding regions in the network that are heavily depleted of energy, improvements in network lifetime are possible by reducing traffic volume in the network. To that end, this section discusses data funneling, a protocol that performs data aggregation while routing packets in the network. It is based on the energy-aware routing protocol, but instead of sending multiple packets from all nodes in a region, packets are aggregated along the...

Classification and Comparison of MAC Protocols

Classification Mac Protocols

In general, wireless communication has a variety of MAC protocols, which can be classified into distinct groups according to different criteria. Based on whether a central controller is involved in coordination, WSNs' MAC protocols can be categorized as centralized, distributed (decentralized), and hybrid. Actually, hybrid protocols attempt to combine the advantages of centralized and distributed schemes, but can be more complex. Figure 18.3 shows such classification 97 . Centralized MAC...

Sensor Ware

SensorWare 5, 6 is another active sensor framework developed at UCLA. This framework uses a highlevel scripting abstraction based around Tcl 23 and a highly expandable run-time environment. The run-time environment provides multiple services that achieve the sharing of the sensor node's resources among multiple applications. The programming model is event based with event handlers to react to various high-level, application-specific events that occur during a period of interest. The...

Delaunay Triangulation and Voronoi Diagram

Delaunay Triangulation Digital Diagram

Assume that no four vertices of V are cocircular. A triangulation of V is a Delaunay triangulation, denoted by Del V , if the circumcircle of each of its triangles does not contain any other vertices of V in its interior. A triangle is called the Delaunay triangle if its circumcircle is empty of vertices of V see Figure 39.2 d for an illustration. The Voronoi region, denoted by Vor p , of a vertex p e V is a collection of two FIGURE 39.4 The Voronoi diagram and Delaunay triangulation of a set...

Restricted Delaunay Graph

Gao et al. 55 also proposed another structure, called restricted Delaunay graph RDG and showed that it has good spanning ratio properties and can be maintained locally. A restricted Delaunay graph of a set of points in the plane is a planar graph and contains all the Delaunay edges with length of, at most, one. In other words, these authors call any planar graph containing UDel V a restricted Delaunay graph. They described a distributed algorithm to construct a RDG such that, at the end of the...

Single Packet Storage Methods

Numerous methods can be used to model packet generation, storage, and erasure. Here, five possible methods are considered JUSTTTL FULL_ERASE IMMUNE IMMUNE_TX and VACCINE. These methods progressively extend one another. In all of them, the original packet and all of its copies are erased Tp F-1 Pthresh time steps after the original packet was created. JUST_TTL is the simplest method. All packets remain in the system until Tp F-1 Pthresh time steps have elapsed from the original packet creation....

Directional Source Aware Routing Protocol DSAP

In order to resolve the problems of power efficiency, a unique identification system has been developed for the networks used. The idea behind this identification system is to identify the location of each node in the network that will help in routing the packets. The system has the following properties Each value represents how far the node is from a certain direction. Each ID gives how far the node is from the nodes in each direction. Each node can compute the direction of other nodes from...

Motivation and Design Issues in WSN Routing

One of the main design goals of WSNs is to prolong the lifetime of the network and prevent connectivity degradation by employing aggressive energy management techniques. This is motivated by the fact that energy sources in WSNs are irreplaceable and their lifetime is limited. However, the positions of the sensor nodes are usually not engineered or predetermined and thus allow random deployment in inaccessible terrain or disaster relief operations. This implies that the nodes are expected to...

Design Choices

Sensor nodes, also called wireless transceivers, are tiny devices equipped with one or more sensors one or more transceivers processing storage resources and, possibly, actuators. Sensor nodes organize in networks and collaborate to accomplish a larger sensing task. One important class of WSNs is wireless ad hoc sensor networks WASN , characterized by an ad hoc or random sensor deployment method in which the sensor location is not known a priori. This feature is required when individual sensor...

Transmission Power Control

In the previous sections, it has been assumed that the transmission power of every node is equal and is normalized to one unit. This assumption is relaxed for a moment in this section. In other words, assume that each node can adjust its transmission power according to its neighbors' positions. A natural question is then how to assign the transmission power for each node so that the wireless sensor network is connected with optimization criteria minimizing the maximum or total transmission...

Application Layer Protocols

Although many application areas for sensor networks are defined and proposed, potential application layer protocols for sensor networks remain largely unexplored. Three possible application layer protocols are introduced in this section sensor management protocol task assignment and data advertisement protocol and sensor query and data dissemination protocol. These protocols may require protocols at other stack layers explained in the remaining sections of this chapter . 16.2.2.1 Sensor...

References

Clare, An integrated architecture for cooperative sensing networks, Computer Mag., 33 5 , 106-108, 2000. 2. I.F. Akyildiz, W. Su, Y. Sankarasubramaniam, and E. Cayirci, Wireless sensor network a survey, Computer Networks, 38 4 , 393-422, March 2002. 3. G. Anastasi, L. Lenzini, and E. Mingozzi, Stability and performance analysis of HIPERLAN, IEEE INFOCOM 1998, 1, 134-141, San Francisco, 1998. 4. G. Asada et al., Wireless integrated network sensors low power systems on a chip,...

UCLA Medusa MK2 Node

The Medusa MK-2 node is a representative of the state-of-the-art design of more powerful sensor nodes 55 . The computational unit of Medusa MK-2 nodes consists of two microcontrollers. The first is an 8-b Atmel STMega128L MCU with 4 MHz that has 32 K of flash memory and 4 KB of RAM. This processor serves as an interface between sensors and radio base band processing. The second microcontroller is an ATMEL ARM THUMB processor enclosed within a 120-ball BGA package. It has significantly more...

Handbook of Sensor Networks Compact Wireless and Hired Sensing Systems

Boca Raton London New York Washington, D.C. Library of Congress Cataloging-in-Publication Data Handbook of sensor networks compact wireless and wired sensing systems edited by Mohammad Ilyas and Imad Mahgoub. p. cm. Includes bibliographical references and index. ISBN 0-8493-1968-4 alk. paper 1. Sensor networks. 2. Wireless LANs. I. Ilyas, Mohammad, 1953- II. Mahgoub, Imad. TK7872.D48.H36 2004 This book contains information obtained from authentic and highly regarded sources. Reprinted material...

Bitbus Updated as IEEE 1118

Bitbus, developed by Intel, is one of the oldest serial buses for industrial use. The bitbus specification allows interconnecting 28 nodes over a distance of 30 m for synchronous mode with bit rate 2.4 Mb s up to 250 nodes over 13.2 km in a self-clocked mode with bit rate 62.5 kb s. Topology one or more interconnected buses Maximum length 13.2 km with 62.5 kb s and 250 nodes maximum of 28 nodes per segment Medium access control master-slave with acknowledgment Data transmission rate 62.5 kb s...

Combining Face Routing with Greedy Routing

Greedy routing was used in early routing protocols for wireless networks. However, it is easy to construct a simple example to show that greedy algorithm will not succeed to reach the destination but fall into a local minimum, a node without any better neighbors. A natural approach to improve the potential of greedy routing for practical purposes is to combine greedy routing and face routing or the right-hand rule to recover the routing after simple greedy routing fails in local minimum. Many...

Nine Bit Interprocessor Protocol

The NBIP 9-b interprocessor protocol NBIP 10 is a character-oriented data-link layer communication protocol for a master-slaves multidrop configuration with polling. The protocol makes full use of the so-called multiprocessor communication modes, which are based on 9-b characters. The NBIP communication procedure was designed by Intel's researchers to fit serial ports of the MCS-51 and MCS-96 families of microcontrollers interconnected by a serial bus nevertheless, such communication modes are...

Self Organizing MAC for Sensor Networks SMACS and Eavesdrop and Register EAR Algorithms

Self-organizing MAC for sensor networks SMACS is designed for network startup and link layer organization in a static WSN 17 it is one of the earliest attempts to develop MAC protocols for sensor networks. In this scheme, each node maintains a TDMA frame in which the node schedules different time slots to communicate with its known neighbors. During each time slot, it only talks to one neighbor. To avoid interference between adjacent links, the protocol uses different frequency channels FDMA or...

Foundation Fieldbus

Foundation fieldbus is the result of cooperation of the ISP Interoperable System Project and WorldFIP initiatives. It is the youngest and the most advanced fieldbus for industrial applications, namely, for process control in chemical, pharmaceutical, petrochemical, and other processing industries. Foundation fieldbus in the H1 variant can be used also for the explosive area because it is based on the IEC 1158-2 physical layer standard. Foundation fieldbus nodes can be classed as basic devices...

EAR Algorithm

The EAR algorithm enables seamless interconnection of mobile nodes in the field of stationary wireless nodes. This protocol performs the mobility management of the network allowing mobile nodes to listen to the communication from the stationary nodes and establish connectivity with them. Because of energy limitations, the communication channels between the mobile and stationary sensors in the network must be established using as few messages as possible. This is accomplished by allowing the...

DVS Circuit

The basic variable core power supply schematic is shown in Figure 27.5. The MAX1717 step-down controller is used to regulate the core supply voltage dynamically through the 5-b digital-to-analog converter DAC inputs over a 0.925 to 2 V range. The converter works on the following principle. A variable duty cycle pulse width modulated PWM signal alternately turns on the power transistors M1 and M2. This produces a rectangular wave at the output of the transistors with duty cycle D. The LC...

Minimum Spanning Tree Relative Neighborhood Graph and Gabriel Graph

Relative Neighborhood Graph

The minimum spanning tree of G, denoted by MST G , is the tree belonging to E that connects all nodes and whose total edge length is minimized. MST G is obviously one of the sparsest connected subgraphs, but its stretch factor can be as large as n - 1. The relative neighborhood graph, denoted by RNG G , is a geometric concept proposed by Toussaint 148 . It consists of all edges uv e E such that there is no point w e Vwith edges uw and wv in E satisfying lt uv and wv lt uv . See Figure 39.2 a...

Routing in WSNs Future Directions

The future vision of WSNs is to embed numerous distributed devices to monitor and interact with physical world phenomena and to exploit spatially and temporally dense sensing and actuation capabilities of those sensor networks. These nodes coordinate among themselves to create a network that performs higher level tasks. Although extensive efforts have been exerted so far on the routing problem in WSNs, some challenges still confront effective solutions of the routing problem. First, there is a...

Management Dimensions

In general, for traditional networks, management aspects are clearly separated from network common activities, i.e., from the services they provide to their users. It is also said that an overlap of management and network functionalities exists, although the implementation can be thought of independently. This separation can be promoted by using two traditional management dimensions management functional areas 14 and management levels 15 . The requirements to be satisfied by systems management...

Opportunities

1.2.1 Growing Research and Commercial Interest Research and commercial interest in the area of wireless sensor networks are currently growing exponentially, which is manifested in many ways The number of Web pages Google 26,000 hits for sensor networks 8000 for wireless sensor networks in August 2003 Dedicated annual workshops, such as IPSN information processing in sensor networks SenSys EWSN European workshop on wireless sensor networks SNPA sensor network protocols and applications and WSNA...