Questions and Answers of Introduction Wireless Mobile Systems

A conference organizer decided to have eight separate groups of panels€”A, B, C, D, E, F, G, and H€”to make decisions on eight parallel tracks for a professional meeting. To
In Problem P15.8, it was decided to add five additional channels, (f6, f7, f8, f9, f10) while keeping the frequency hopping sequence to five bands. Is it advisable to maintain frequency hopping
In a hypothetical wireless system, five adjacent frequency bands (f1, f2, f3, f4, f5) are allowed for frequency hopping sequences. Enumerate how many different hopping sequences are possible and
What impact will Bluetooth devices connected to mobile units have on the piconet?
Do Bluetooth devices and household microwave ovens interfere? Explain.
A set of small robots needs to be equipped with wireless devices. Consider the usefulness of the following devices if used in a laboratory environment:(a) WMAN(b) WLAN(c) WPAN
Repeat Problem P15.3, if the robots are employed for a field application.Repeat ProblemA set of small robots needs to be equipped with wireless devices. Consider the usefulness of the following
A set of small robots needs to be equipped with wireless devices. Consider the usefulness of the following devices if used in a laboratory environment:(a) Infrared (IR)(b) Diffused infraredObtain
You might have observed the following:(a) When you open your garage door, your next-door neighbor’s door might also open.(b) Your neighbor complains sometimes that the TV channel is changing
In Problem 14.29, can you comment on the possible use of(a) Ad hoc network.(b) Sensor network.(c) Bluetooth devices.(d) ZigBee(e) HomeRF(f) 802.11 enabled devices(g) WiMax
Using your favorite website, find different type of sensors if the idea is to explore the following applications:(a) Nuclear plant.(b) Under water project.(c) Noise level in a campus.(d) Air
Repeat Problem P14.20 to divide the network into four sets of €œsleep-awake€ cycles? 3
Repeat Problem P14.19, for a lake of size 250m length × 50 m width × 5 m deep, if biosensors are to be installed to monitor pollutant level and if the range of each sensor is 0.5 m.
Given the power model of Problem P14.7, determine the energy consumption of the scheme in Problem P14.8.
In Problem P14.2, assume the cluster members are divided into two groups of four sensors each and they take turn in going to sleep-awake modes while reporting to the CH. What is the overall effect on
Repeat Problem P13.20 for a 56 m long airplane, whose cross-section is represented as shown in Figure 14.24. 15m 7m
What will be the impact in Problem P13.21 if the sensor range could be increased to 10 m?
What changes do you need to make in Problem P14.7 if the APTEEN protocol is to be used?
In Problem P14.2, what happens to the performance if the sensors are halved? Explain.
Repeat Problems P14.8 and P14.9 for the hexagonal topology shown in Figure 14.24.
Using the energy consumption by different functions in a sensor of Problem P14.2, determine the energy consumption in the following topologies:(a) How much energy is consumed for transmission to the
What happens if you use two household cordless phones at the same time? Explain with appropriate reasons.
Can you think of ten important parameters that ought to be sensed in a futuristic automobile? What type of sensors do you need to monitor them constantly?
What are the uses of different types of queries in sensor networks? Explain clearly.
For what applications are direct-diffusion based flat architectures or cluster based sensor networks useful? Explain in detail.
From your favorite Web site, find what is meant by “gossiping-based routing.” What are the advantages and limitations of such an approach? Explain clearly.
Can the past response location of a query be helpful in limiting the flooding area? Explain clearly.
How can you divide triangular- and hexagonal-based sensor networks into multiple “sleep-awake” sets? Explain clearly.
Given a 2-D rectangular topology of 20x20 size, can you divide the network into two subsets for “sleep-awake” cycles? Justify the correctness of your answer.
A clustering approach has been suggested to locally collect and “aggregate” information in a sensor network. What kind of aggregation is desirable?
What are the advantages and limitations of a “directed-diffusion” approach in a sensor network? Explain clearly.
Why do you use a “data-centric” approach in a sensor network?
A wireless sensor has a transmitter/receiver range of 2 m, and many such sensors need to be installed in a nuclear plant building of size 50 mx50 m with the height of 25 m. Can you think of an
What kind of clustering is possible for the triangular topology of Figure 14.23? How about the location of the CH?
Assume that CDMA/TDMA is used for each cluster of 4x4 size within a given 8x8 grid. Can you come up with a time-slot schedule for each cluster of the sensor network when the TEEN protocol is to be
In Problem P14.2, assume the number of sensors is doubled in each cluster. What is the impact on the performance? Explain clearly.
In a sensor network, the energy consumed by different functions by a sensor is as follows:Assume the total number of nodes as P, the number of cluster heads to be m, the number of sensor nodes which
Use your favorite search engine to find out what is meant by the ‘self-organizing property of sensor networks’?
What are the similarities and differences between ad hoc networks and sensor networks? Explain clearly.
If you are given a choice of using either reactive or proactive routing protocol, which one would you prefer for Problem P15.7 with ad hoc network and why?
Given a MANET consists of n wireless devices, what can you say about the capacity of the network? How is this related to a VANET?
What are the similarities and differences between VANET in a city versus a rural area? Explain clearly.
How can you ensure that the path obtained in Problem P13.21 is followed and other alternate paths are disabled? Think about this and answer carefully.
A VANET in a city area is shown in Figure 13.14. What is the transmission path you would select to send a message from device G to device A? H 0- B D
What are the similarities and differences between ad hoc networks and VANETs? Explain clearly.
Assuming four clusters of 4 × 4 size are used for the MANET of Problem P13.16. Find the appropriate location of the CH such that the average distance from the cluster member is minimum.
In Problem 13.16, coordinates of each node are represented by (x,y) digits, with one corner being (0,0) and other three corners being (0,7), (7,0) and (7,7). Assuming that two messages are to be sent
In a MANET, any node can be selected as a source or a destination. Assuming equal probability of a node being selected as a source or destination, what is the average number of hops the message has
Assume that 64 nodes form a MANET in the form of 2-D grid. If an arbitrary source node is selected, what is the maximum number of hops a message has to travel? Calculate that carefully.
What are the advantages and disadvantages of reactive and proactive protocols? Which one would you prefer and why? Explain with specific conditions.
What are the implications of using CDMA in an ad hoc network? Explain in detail.
What is meant by piggybacking, and what are the advantages? Explain clearly.
Illustrate how multipath routing can be done between nodes 1 and 26 of Problem P13.7. Which multipath routing technique is beneficial and why? Explan clearly.A snapshot of an ad hoc network is shown
Consider an ad hoc network in which communication (message or packet transfer) is to take place from node X to node Y. The route has already been established, and a data packet is to be transferred
In ad hoc networks, it is sometimes desirable to transmit packets of a single message using multiple paths using an 802.11 protocol.(a) Can you think of any specific reasons for this?(b) If you need
Assuming that the location of the destination node 23 is known to be located in the northeast direction, what changes do you need to make in determining a route in Problem P13.7? Explain clearly. 23
How does signal stability affect the route in Problem P13.7? (3 1) (16 10 15 (19 (21) 14 20
Repeat Problem P13.5, if the distance is changed to 8 hops.(a) The number of alternate paths of length of 5 hops?(b) Alternate disjoint paths of length 5 hops?
In Problem P13.4, if the destination node is located at 5 hops apart from a given source node, what is the maximum possible value of(a) The number of alternate paths of length of 5 hops?(b) Alternate
In Problem P13.3, if the updated message is sent every 5 seconds, what is the upper limit on the number of messages initiated periodically if a table-driven routing protocol is to be used? Explain
A given ad hoc network consists of 100 nodes, and the mobility of the nodes is such that every one second, two existing radio connections are broken, while two new radio links are established.
Why is it not possible to use circuit switching in ad hoc networks?
What are the differences between cellular and ad hoc networks?
Forthcoming 802.11ac APs is expected to have a smaller coverage range than existing standards. Then, what features makes it attractive for its future use?
An 802.11N AP employs MIMO. What is its role in enhancing the performance?
An 802.11G AP employs OFDMA. What is its role in enhancing the performance?
Why is security an issue in an AP?
How many users can a wireless AP handle? What happens if the number of MSs exceeds this value?
In question P12.4, if the radius covered by an AP is doubled by updating the version of the APs. How much reduction in the number of APs you anticipate? Explain clearly.
In question P12.4, what kind of covergae area you expect by an AP? Can you assume the area covered by an AP to be rectangular in shape?
Repeat P12.4 when the topology is to be used is in the form of a triangular topology and sensing area overlap is 10% smaller than the mesh topology.
Repeat P11.2 when the topology is to be used is in the form of a hexagonal topology similar to cell phones and has about 10% more overlap in the sensing area between two adjacent sensors.
An AP covers an area of 50,000 m2. If an area of area of 10,000,000 m2 is to be covered by many APs. How many APs will be needed if deployed in a mesh topology?
Is the AP at a café or an executive mansion similar to the one used in an institution or home?
What is the future of SMS services, and how do you compare them with paging? Explain clearly.
What is the fundamental principle and use of spread spectrum?
Search the various Web sites and find why IS-41 message transfer employs X.25.
Repeat Problem P11.16 for IMT2000 system.How would you address Problem P11.15 if a GSM scheme is to be employed?
How would you address Problem P11.15 if a GSM scheme is to be employed?(a) All employees are located in the same city?(b) Fifty percent of employees are in one location, while the remaining 50% are
A large company consists of 10,000 employees, and an infrastructure needs to be created to broadcast messages to all the employees. If an AMPS system is to be used for such a broadcast, what may be
Why is the near-far problem present in CDMA and not in FDMA?
What is the rationale behind the traffic channel indicating the reverse control channel to be busy in AMPS?
In IMSI, why is a temporary ID used? Explain clearly.
One approach to using Walsh code in a CDMA system is to assign a code permanently to each subscriber. What are the advantages, disadvantages, or limitations of such an approach?
What is the function of ACSE and ROSE service elements? Explain clearly.
Why is a smart card needed in GSM, while it is not required in AMPS? Explain the logic behind this.
How do you compare AMPS and GSM systems in terms of coverage area, transmitting power, and error control? Explain.
What are the important functionalities of SS7? Explain their use.
What is the role of different functional planes in GSM? Explain each one clearly.
Where does the MAC sublayer lie on the ISO-OSI layer hierarchy? What issues are handled in this sublayer?
How do you differentiate between different types of handoff? Explain.
What is meant by logical channel, and how is the concept useful? Explain.
IPv6 supports resource allocation. Explain how this is achieved.
What are the advantages of IPv6? Discuss whether an IPv6 network can support IPv4 packets and, if so, how?
What kind of security measures are used in different layers of TCP/IP? Explain.
Given the figure in Problem P10.19 as the connectivity graph of a network, you are allowed to go through only two steps of the Bellman-Ford algorithm at each node so that their complexity (and hence
How many iterations are needed to calculate the shortest path to all nodes from node 3? Determine the shortest distance to each node and the path used for each one of them. 7. 3.
Can any of the methods (e.g., I-TCP, M-TCP, SACK, EBSN) be used to improve performance of TCP over wireless ad hoc networks? Suggest any ways by which this can be done.
Even though explicit bad-state notification (EBSN) appears to be a very pragmatic approach for improving TCP performance over wireless networks, what is its most significant disadvantage?
Both I-TCP and M-TCP are split TCP approaches to improving the performance of wireline TCP over wireless networks. What is the difference between these two approaches?

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