Wireless Sensor Networks Challenges Quiz
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Questions and Answers

In which mode are system calls executed after interrupting the user processes?

  • Parallel mode
  • Kernel-mode (correct)
  • User-mode
  • Hybrid mode

    • What are some situations where system calls are typically made by user level programs?

  • Creating databases, formatting hard drives, installing software, updating the operating system
  • Manipulating files, managing processes, network connections, accessing hardware devices (correct)
  • Printing documents, browsing the internet, playing audio files, sending emails
  • Changing system settings, customizing the desktop, running antivirus scans, defragmenting disks

    • What happens once the execution of a system call is completed?

  • Kernel-mode is exited
  • The system call is repeated
  • Control returns to the user mode (correct)
  • User processes are paused indefinitely

    • Which of the following is NOT a typical situation for making system calls by user level programs?

    <p>Creating animations on the screen</p> Signup and view all the answers

    What purpose do system calls serve in the context of accessing hardware resources?

    <p>Allow users to access hardware without worrying about low-level details</p> Signup and view all the answers

    What is one of the challenges in Wireless Sensor Networks related to multi-hop communication?

    <p>Increased latency</p> Signup and view all the answers

    How is power conservation managed in Wireless Sensor Networks?

    <p>By switching off radios when not in use</p> Signup and view all the answers

    What is one strategy mentioned for Wake-up and demand Duty Cycling in Wireless Sensor Networks?

    <p>Node can wakeup whenever needed</p> Signup and view all the answers

    Why is centralized management often not feasible in Wireless Sensor Networks?

    <p>Energy constraints and large scale of networks</p> Signup and view all the answers

    What is a key advantage of decentralized (or distributed) solutions in Wireless Sensor Networks?

    <p>Better performance than centralized solutions</p> Signup and view all the answers

    How do nodes manage Adaptive Duty Cycling in Wireless Sensor Networks?

    <p>A subset of nodes remain active to form a network backbone</p> Signup and view all the answers

    What is the purpose of task scheduling in an operating system?

    <p>To organize, prioritize, and execute tasks efficiently</p> Signup and view all the answers

    Which type of data types in Wireless Sensor Networks (WSN) consume more resources but have strong expressive power?

    <p>Complex data types like structs and enums</p> Signup and view all the answers

    What distinguishes a single-user operating system from a multi-user operating system?

    <p>Ability to allow only one user at a time vs. multiple users concurrently</p> Signup and view all the answers

    Which aspect of an operating system focuses on handling interruptions and system calls?

    <p>Scheduling</p> Signup and view all the answers

    What plays a key role in determining the efficiency of an operating system?

    <p>Task Scheduling</p> Signup and view all the answers

    Why are simple data types preferred in Wireless Sensor Networks (WSN)?

    <p>Because they consume fewer resources and provide limited expressive capability</p> Signup and view all the answers

    What is a major concern in resource-constrained processors?

    <p>Efficient execution of algorithms</p> Signup and view all the answers

    Which architecture employs a single memory space for program instructions and data?

    <p>Von Neumann architecture</p> Signup and view all the answers

    Why are special-purpose, energy-efficient processors not suitable for tasks requiring frequent updates or remote debugging?

    <p>Lack of processing space</p> Signup and view all the answers

    What type of processors are considered the best option for dynamic code installation and update in WSNs?

    <p>Microcontroller</p> Signup and view all the answers

    Which aspect of a processor subsystem involves the transferring of information from and to memory?

    <p>Program instructions and data transfer</p> Signup and view all the answers

    In the context of processor subsystems, what do program instructions relate to?

    <p>Communication, self-organization, data compression, and aggregation algorithms</p> Signup and view all the answers

    What is the main reason for needing dynamic reprogramming in wireless sensor networks?

    <p>To enhance network performance</p> Signup and view all the answers

    Why is manual replacement not considered feasible in the context of wireless sensor networks?

    <p>It may introduce bugs and errors</p> Signup and view all the answers

    What is a key requirement for an operating system to support dynamic reprogramming effectively?

    <p>Clear separation between application and OS</p> Signup and view all the answers

    Why is portability important for operating systems in wireless sensor networks?

    <p>To accommodate unforeseen requirements</p> Signup and view all the answers

    What role does an operating system play in dynamic reprogramming?

    <p>Updating software components in the right order</p> Signup and view all the answers

    Why should operating systems ideally be portable and extensible?

    <p>To accommodate unforeseen requirements</p> Signup and view all the answers

    Study Notes

    Wireless Sensor Networks (WSN)

    • WSNs face challenges in wireless networking, including:
      • Multi-hop communication, which increases latency and error probability, and is complicated by power conservation policies.
      • Decentralization, as centralized management is often not feasible due to the large scale of the network and energy constraints.

    Power Conservation Policies

    • Duty Cycling is used to conserve power:
      • Wake-up and demand duty cycling: nodes can wake up when needed, using a low-power radio to receive wake-up calls and a high-power radio to respond.
      • Adaptive duty cycling: not all nodes sleep at the same time, and a subset of nodes remain active to form a network backbone.

    Operating System (OS)

    • System Calls:
      • Users invoke system calls to access hardware resources, such as sensors, watchdog timers, or radios.
      • Steps involved: user mode, system call execution in kernel-mode, and returning to user mode.

    Functional Aspects of OS

    • Data Types:
      • Interactions between subsystems occur through well-formulated protocols and data types.
      • Data types include complex types (struct and enum) and simple types (C programming language).
    • Scheduling:
      • Task scheduling organizes, prioritizes, and executes tasks to determine OS efficiency.
      • Two scheduling mechanisms are used.

    Node Architecture: Processor Subsystem

    • A major concern is efficient execution of algorithms, requiring transfer of information from and to memory.
    • Processor subsystem can be designed using one of three basic computer architectures: Von Neumann, Harvard, or Super-Harvard (SHARC).

    Non-Functional Aspects of OS

    • Portability:
      • OS should be able to co-exist and collaborate with other OS.
      • Existing OS do not provide this support.
    • Dynamic Reprogramming:
      • Necessary for unforeseen requirements, including changes in network performance, application requirements, or environment.
      • Requires clear separation between application and OS, and OS support for updates and assembly.

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    Test your knowledge on challenges faced in Wireless Sensor Networks, such as multi-hop communication, increased latency, failure probability, and power conservation policies.

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