CWISA-103 Sample Questions Answers

BLE Beacon Power Efficiency: Bluetooth Low Energy (BLE) beacons are designed for low power consumption. Their primary function is to periodically broadcast short data packets (advertising their presence).

Other Technologies:

Cellular: More power-hungry due to long-range communication and complex protocols.

GPS: Power intensive, especially when actively tracking location.

Wi-Fi:

Decibel (dB): A logarithmic unit expressing ratios of power or signal strength. It's used in RF contexts due to the wide range of signal levels encountered.

Examples:

dBm: Decibels relative to one milliwatt (power measurement).

dBi: Decibels relative to an isotropic antenna (antenna gain).

References

Decibel: https://en.wikipedia.org/wiki/Decibel

Attenuation: Describes the progressive loss of signal strength as it travels through a medium (like air, cables, walls). It's caused by factors like absorption, distance, and obstacles.

Other Phenomena:

Diffraction: Bending of waves around obstacles.

Reflection: Waves bouncing off surfaces.

**Scattering: ** Waves dispersing in multiple directions.

References

Attenuation: https://en.wikipedia.org/wiki/Attenuation

SSL/TLS Secures Web Traffic: HTTPS builds upon HTTP, adding the encryption provided by Secure Sockets Layer (SSL) or its successor, Transport Layer Security (TLS).

Other Protocols Have Different Purposes:

IPSec: Secures IP traffic at a network level, can be used alongside TLS.

SNMPv3: Management protocol, offers security features, but not the primary mechanism in HTTPS.

SSH: Secure remote shell, unrelated to web data encryption.

The concept described is Free Space Path Loss (FSPL). FSPL refers to the reduction in power density of an electromagnetic wave as it propagates through a clear, unobstructed path in free space. This weakening of the signal is due to the spreading of the wavefront as it travels, causing the power to be distributed over a larger area. The FSPL can be calculated using the Friis Transmission Equation, which shows that the received power decreases with the square of the distance from the transmitter. This concept is fundamental to understanding the behavior of RF signals in various communication systems, including wireless IoT, where the signal strength at the receiver is a critical factor for reliable data transmission.

LoRa: Refers to the physical layer chirp spread spectrum (CSS) modulation, enabling long-range, low-power communication.

LoRaWAN: An open MAC layer protocol that builds on LoRa, defining network architecture, device management, and data routing for large-scale LoRa networks.

Firmware Definition: Firmware is a type of software embedded in hardware devices. It provides low-level instructions that control the basic operations and initialization of the device.

ROM Storage: Firmware is typically stored in Read-Only Memory (ROM) or other forms of non-volatile memory, meaning it persists even when the device is powered off.

Functions:

Booting: Initiates the hardware and loads the operating system.

Hardware Control: Provides an interface between the hardware and the operating system.

BIOS: The firmware on PCs is often referred to as BIOS (Basic Input/Output System).

References

Firmware Explanation: https://en.wikipedia.org/wiki/Firmware

ROM: https://en.wikipedia.org/wiki/Read-only_memory

Perception Layer: The foundation of an IoT system, it consists of sensors and actuators that:

Sense: Collect data about the environment or object being monitored.

Actuate: Potentially make changes based on commands (e.g., a smart valve opening/closing).

Transmit: Send gathered data to upper layers for processing.

ITU's Mandate: The International Telecommunication Union (ITU) is a specialized agency of the United Nations focused on global information and communication technologies (ICTs).

Radio Spectrum Regulation: A core ITU function is allocating radio spectrum bands and satellite orbits to prevent harmful interference between different countries and technologies. This coordination is essential for the orderly use of wireless communications worldwide.

Other ITU Roles: While involved in standard-setting and establishing best practices, options A and D are less precise than the ITU's spectrum coordination focus.

Browser Ubiquity: JavaScript has a native runtime environment within almost every modern web browser, making it the 'built-in' scripting language for web-based interfaces.

Node-RED: This IoT flow-based programming tool specifically uses JavaScript for its logic and automation functions.

Other Languages:

PHP: Primarily server-side for web applications

Python: Versatile language, used in some back-end IoT functions but not natively in browsers

R: Statistical and data analysis, not typically embedded in wireless solutions

WWAN (Wide-Area Wireless Network): WWANs provide connectivity over extensive geographic areas, typically covering regions or even entire countries.

Cellular Technology: WWANs often rely on cellular networks (3G, 4G, 5G) offered by mobile carriers.

References

WWAN: https://en.wikipedia.org/wiki/Wireless_wide_area_network

Outsourcing Knowledge Transfer: When outsourcing implementation, the service provider has firsthand knowledge of system setup and configuration. Clear documentation ensures this knowledge remains accessible to you after the project is complete.

Ongoing Support: While paid/free support options influence long-term maintenance, they won't substitute missing documentation about the specific setup.

Reducing Future Vendor Reliance: Detailed documentation helps mitigate over-reliance on the service provider for minor changes and troubleshooting, giving you more long-term autonomy.

Proof of Concept: A POC typically happens before outsourcing, and focuses on validating the solution's feasibility, not ensuring smooth knowledge transfer thereafter.

60GHz Absorption: The 60GHz band experiences significant signal attenuation due to absorption by oxygen molecules in the atmosphere. This severely restricts the usable range of wireless systems operating in this frequency.

Why Other Options Don't Apply:

Atmospheric Scattering: Impacts longer wavelength transmissions, less significant at 60GHz.

Solar Radiation: Can cause interference on some frequencies, but not a primary range limitation at 60GHz.

Rain Fade: Primarily affects higher frequencies (above 10GHz), but its impact is less severe than oxygen absorption at 60GHz.

LoRa: This refers to the underlying radio modulation technique using Chirp Spread Spectrum (CSS). It defines how data is physically encoded onto the wireless signal.

LoRaWAN: This is the network protocol built on top of LoRa. It manages device communication, network topology, and aspects like security. It operates at the MAC sublayer of the Data Link layer (Layer 2) of the OSI model

LoRa vs. LoRaWAN: Key takeaway is that LoRa is the physical layer technology, while LoRaWAN adds the networking layer for management.

Importance of Time Sync in IoT: Coordinated actions, accurate data analysis, and event logging in wireless IoT solutions often rely on devices having a shared time reference.

NTP's Role: Network Time Protocol (NTP) enables devices to synchronize their clocks against a reliable time source (NTP server), ensuring consistency across the network.

Why Other Options Don't Fit:

IP Addressing: Usually handled by DHCP, not NTP.

Encryption: SSL/TLS secure data in transit, not related to timekeeping.

Name Resolution: Purpose of DNS, not NTP.

PHP's Cross-Platform Nature: PHP originated for server-side web development, but also has a command-line interface (CLI) enabling its use for scripts and automation tasks.

Other Options:

Some languages are OS-specific (but less frequent with modern scripting languages) .

Many languages work in web or command line, not both like PHP.

Free Space Path Loss (FSPL): Describes how a radio signal weakens as it travels through open space, even without obstacles. It's caused by the signal spreading out, resulting in decreased power density at the receiver.

Calculation: FSPL depends on distance and frequency.

References

Free Space Path Loss: https://en.wikipedia.org/wiki/Free-space_path_loss