CWISA-103 Certified Wireless Iot Solutions Administrator Practice Questions

RSSI is a measurement of the raw power of the signal as it arrives at the receiver. LQI, however, is a more comprehensive metric that assesses the quality of the demodulated packet. It is often derived from the signal-to-noise ratio (SNR) or the packet error rate. It is possible to have a high RSSI (strong signal) but a low LQI if there is significant interference, meaning the signal is strong but corrupted.

Sigfox is an LPWAN technology where the network infrastructure is deployed and managed by a Sigfox Network Operator (SNO). Customers subscribe to the service, eliminating the need to build and maintain their own gateways. This model perfectly fits the city's requirement to avoid capital expenditure on infrastructure. Sigfox's use of ultra-narrowband modulation is extremely power-efficient, enabling the required multi-year battery life for the sensors.

Preamble Puncturing, a key feature of Wi-Fi 7 (802.11be), allows a device to carve out and use only the clear portions of a wide channel, 'puncturing' or ignoring the sub-channels that have interference. This enables the use of the remaining parts of the wide channel instead of falling back to a narrower one, thus improving spectral efficiency and maintaining higher throughput even in congested environments.

The primary advantage of an SoC is the high level of integration. By placing the processor, memory, I/O controllers, and often a wireless radio onto a single piece of silicon, the physical footprint of the electronics is drastically reduced. Furthermore, the short electrical paths between components on the same chip lead to lower power consumption compared to a design using discrete components on a larger circuit board.

A crucial aspect of coexistence is their different channelization. Wi-Fi uses wide channels (20 MHz or more), and best practice dictates using non-overlapping channels 1, 6, and 11. Zigbee uses much narrower 2 MHz channels. This allows Zigbee channels (specifically 15, 20, 25, and 26) to be placed in the spectral gaps between the standard Wi-Fi channels, which is a key strategy for mitigating interference.

Adaptive Data Rate (ADR) in LoRaWAN adjusts the spreading factor (SF) to optimize battery life and network capacity. In unstable RF environments, such as an open yard with moving metal containers causing reflections and fading, the ADR algorithm might misinterpret a temporarily strong signal as a stable link improvement. It would then command the sensor to use a lower SF (higher data rate), which requires a better signal-to-noise ratio. When the temporary good condition vanishes, the signal is too weak to be demodulated at the lower SF, leading to packet loss. The log pattern of data rate changes followed by silence is a classic symptom of overly aggressive ADR.

Network slicing is a key 5G feature that allows the creation of virtual end-to-end networks tailored to specific applications. For URLLC, a slice can be configured with dedicated resources and quality of service (QoS) parameters to guarantee low latency and high reliability for the critical AMR control data, isolating it from other less critical traffic.

Deploying the UPF, which handles data packet routing and forwarding, at the network edge (a concept known as Multi-access Edge Computing or MEC) significantly reduces latency. By processing data locally instead of sending it to a centralized core network, the round-trip time for AMR control commands is minimized, which is essential for URLLC.

False. While operating multiple radios simultaneously can increase instantaneous power draw, MLO can significantly reduce overall energy consumption for battery-powered IoT devices. By aggregating links, the device can transmit its data much faster and return to a low-power sleep state more quickly. This reduction in active time often outweighs the higher instantaneous power draw, leading to net power savings over time.

This solution meets all requirements. BLE tags provide multi-year battery life. Leveraging the integrated BLE radios in the existing Wi-Fi 6E APs requires no new cabling. The APs act as gateways, collecting BLE data without the tags needing to connect to the secure Wi-Fi network, thus bypassing WPA3-Enterprise complexities for the tags themselves. RSSI-based locationing from a dense AP deployment can achieve the required room-level accuracy. The data can then be sent over the existing network to the management platform.

The calculation is as follows:

1. Convert transmitter power to dBm: 100 mW = 20 dBm (since 10 * log10(100) = 20).
2. Calculate total cable loss: 10 meters * 0.5 dB/meter = 5 dB.
3. Calculate EIRP: EIRP (dBm) = Tx Power (dBm) - Cable Loss (dB) + Antenna Gain (dBi).
4. EIRP = 20 dBm - 5 dB + 9 dBi = 24 dBm.