Principles Of Embedded Networked Systems Design 1st Edition Gregory J. Pottie ,William J. Kaiser - Solutions

Database layers and programming How do the database layers of physical, conceptual, and user levels correspond to the layering of computer code between assembly code and compiled C programs?
Resolution of uncommitted dependency Transaction B begins with an update request at time t1 and would ordinarily finish by time t3. In the meantime transaction A begins at time t2,t1
Replication for reduced communication Data replication can provide both robustness and faster response time. A further potential benefit is reduction of long-range communication costs. While on the one hand it is undesirable to replicate all records, on the other hand it is clearly beneficial to
Sufficient sampling A field has the spatial autocorrelation function sincð2x=dÞ;where d is some constant and x is the distance variable.(a) What is the maximum permitted separation of sensors to be able to reconstruct the field perfectly?(b) Why is sampling at exactly this frequency a poor idea
Data storage times Consider a three-tier sensor network. The first tier generates the raw data and keeps it for a period T1. It passes to the second tier its decisions and associated likelihoods. The second tier keeps these for a period T2>T1. It may also request raw data from the first tier within
Refinement with age As data age they are progressively refined into more compact (lossy) representations.Suppose, e.g., that data might be stored in three buffers: raw, reduced resolution, histogram. The value per bit stored increases as the data are compressed, yet the value of the data prior to
Interest diffusion Repeat the problem in Example 11.8 but with sink 1 having interest 4, sink 2 having interest 2, and the cost of each link being 1.
Adaptive sampling The sampling density required in time and space depends on the variability of the phenomenon, the noise, and the reconstruction method. Suppose linear interpolation is to be used and noise is negligible. The function sin x is to be sampled such that the maximum error between the
Deductive arguments Reduce the following arguments to symbolic form and then determine their logical validity.(a) If pigs can fly, then cats can fly; cats cannot fly; therefore pigs cannot fly.(b) If he wants to hire me, he’ll shake my hand; he shook my hand; therefore he wants to hire me.(c) To
Hypotheses about causes Arguments about cause and effect are fraught with peril. The reason is that such arguments are in essence probabilistic rather than deterministic. Discuss the validity of the following inductive arguments.(a) He was shot, and then died. Therefore the bullet killed him.(b)
Green eggs and ham orientation A burning scientific question is how characters in stories end up being green eggs and ham fans/disdainers. Is like/dislike for green eggs and ham an innate property (an orientation) or is it a product of upbringing (a preference) and thus more mutable? Is it a mix of
Going to the dogs Categories (fox, box, goat, boat) enable a compressed description of diverse things which share some attributes. This enables inductive reasoning about things which have never been seen, e.g., all foxes I have seen are four legged, therefore all foxes are four legged. The same
Sensor density and resources(a) Qualitatively, how does increasing sensor density reduce the error in reproducing a source at a fusion center?(b) Instead of increasing sensor density, an administrator decides to provide deterministic mobility to the sensors. Having deterministic mobility means that
Network throughput with mobile nodes Consider a network with n mobile sensors. The source nodes transmit the message to the corresponding destination pair in two steps. In step 1 the source transmits the message to the relays or destination; and in the next step the relays forward the message to
Work, force, and power It is required to lift a sensor node from ground to the height of 40m in 12 s. This work requires 950 J.(a) What force and power are required to lift the sensor?(b) Calculate the mass of the sensor.
Nodes in freefall A sensor node is to be dropped from a height of 15 m, sending out readings as it falls. Calculate the total energy of a 2 kg sensor node when it is dropped at the velocity of 2 m/s. Also, calculate the final velocity of the falling sensor node just before it reaches the ground.
Stepping up A 7.58 stepper motor accelerates from zero to 45.84 steps/s in 1 ms. If the rotor and load inertia, J, is 2103g m2, calculate the required torque.
Effects of environmental obstacles Consider a sensor field deployed at uniform node density,d, which yields an intersensor spacing,a, in a regular grid deployment. Let the area for which one sensor is responsible be denoted by A¼a2. Consider a circular obstacle of diameter, l,which blocks the
Gain from mobility The gain from mobility, G, can be characterized as the ratio of Pmiss (static sensor node) to that of Pmiss (mobile sensor node). Using the same set-up as Problem 12.6, let a¼100, l 2 (5, 20) and the distance of the obstacle x 2 (20, 35). Plot the curves of gain versus obstacle
Shadow area In Figure 12.18, cameras with a 1808 field of view are denoted by triangles and occlusions by dark squares. Mark and calculate the area of the shadow region.
Exploiting gaps Repeat Example 12.17 for Figure 12.19. Figure 12.18 Obstacles and cameras. Figure 12.19 Camera path and obstacles.
The data mule track Consider the four node sensor network as shown in Figure 12.20. Note: G is the data sink. Communication is by means of a data mule. Movement of one unit costs 3Wh.(a) Find the optimal path for the data mule, assuming the data mule must be in close proximity to each sensor to
Distributed environmental monitoring design An ENS application is directed at agriculture control including comprehensive monitoring of soil moisture, solar radiation flux, atmospheric humidity, temperature and wind, and distributed plant imaging in order to monitor growth. In this problem, we
Multihop communications of images The agricultural monitoring system of Problem 13.1 also includes a user requirement by which processed images and data are communicated via multihop links to the data access port. Here, our sensor data record payload is 0.01 kbyte and our image data payload is 0.1
System management protocol For the previous problem, develop a protocol for system management that enables the user to update the system operating schedule via a remote communication to the network through its data access port. Consider that this schedule update for all nodes must be completed
Energy harvesting Consider that the agricultural monitoring system of Problem 13.2 is equipped with solar cell technologies providing 20% efficient photovoltaic solar cell systems.Consider also that the energy harvested by the solar cell systems may be applied without loss to the node system
The Caesar code The Virgine`re family of codes for the alphabet is specified by ci ¼ mi þ ki mod 26 wheremi is the numerical index of the letter in the alphabet (e.g., B¼2), and ki is a component of a key of lengthd. When d goes to infinity and the key is chosen randomly, this is the Vernam
Unicity distance The length of text required to decode enciphered text uniquely when keys are randomly generated is known as the unicity distance.Denoting byH(K) the entropy of the key and by D the redundancy of the text, the unicity distance is defined as HðKÞ=D:There are 26! possible
Euclid’s algorithm Euclid’s algorithm can be used to find the gcd of two integers a andb. Suppose a>b and let {qi} and {ri} be integer quotients and remainders respectively. The algorithm rests on two principles. First, if b dividesa, then gcd(a,b)¼b. Second, if a¼qbþr, then
Factoring products of primes Two ways to decode a public key system are to try out all possible keys and to attempt to factor n¼pq, where p and q are both primes. Let p(x) denote the number of primes less than or equal to x. We have lim x!1 pðxÞx= lnðxÞ¼ 1;hence pðxÞ x ln x for large x.
Hash functions and sensing In message authentication codes, a family of hash functions hk, where k is the secret key, are employed. The properties of good families are:(1) Ease of computation of hk(x), given k.(2) Compression of an input x of arbitrary length into a sequence of fixed length, n.(3)
The noisy sensor Consider the situation in Figure 14.4. Sensor nodes are laid out on a square grid of spacingd. Propagation losses go as the second power of distance. The source to be detected is Gaussian with zero mean and variance 2s, and the noise added at each sensor is independent AWGN with
Network reconfiguration The rectangular grid in Figure 14.4 is also used for relaying. For the electronics used, it costs twice the energy of a hop between nearest neighbors (separated by distance d ) to hop diagonally across the square (e.g. node 2 to node 5) and eight times the energy to go a
Fighting infection Suppose nodes face a constant probability p of being infected (e.g., malfunctioning, taken over) in every time epoch. A mobile agent can visit 1% of the nodes in each epoch and fix/replace them if they are infected. It is further desired that less than 1% of the data produced by
Information theft The compression approach in a sensor network has implications both for scalability and vulnerability to information theft. Consider the network depicted in Figure 14.5.Tier 1 produces 100 data per node; differing levels of compression are applied.Calculate the volume of data at
Physical security An important component in the overall security of a system is the difficulty of physical access for theft or tampering. A rule of thumb is that the electronic and physical security means should present comparable difficulty to would-be attackers, and should have cost commensurate
People and data reliability Data reliability also depends on the users/applications just as security depends on human involvement. List the ways in which confidence (i.e., trust/reputation) is gained among people and comment on how reputation systems for people fit into the overall system integrity

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