CWNA-109 - Certified Wireless Network Administrator

S1G is one of the 802.11 PHYs that is more likely to be used in an industrial deployment but not likely to be used in standard office deployments. This is because S1G stands for Sub-1 GHz, which means it operates in the frequency bands below 1 GHz, such as 900 MHz and 868 MHz. These bands offer better penetration and range than the higher frequency bands used by other 802.11 PHYs, such as 2.4 GHz and 5 GHz. This makes S1G suitable for industrial applications that require robust and reliable wireless communication in harsh environments, such as factories, warehouses, mines, and smart grids. S1G also supports low-power and low-data-rate devices, such as sensors, actuators, and meters, which are common in industrial Internet of Things (IoT) scenarios. VHT, OFDM, and HT are other 802.11 PHYs that are more commonly used in standard office deployments, as they offer higher data rates and capacity than S1G, but have lower range and penetration. References: CWNA-109 Study Guide, Chapter 3: Radio Frequency Technologies, page 751

The final step in an effective troubleshooting process is to document the results. Documentation is essential for keeping track of the problem history, the actions taken, the solutions implemented, and the outcomes achieved. Documentation can also help to prevent future problems, improve best practices, and provide feedback for improvement. Documentation should include relevant information such as problem description, symptoms, root cause analysis, resolution steps, verification methods, and lessons learned. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 513; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 483.

VHT TXOP (Very High Throughput Transmit Opportunity) power save is a feature introduced with the 802.11ac amendment, which is designed to improve the power efficiency of devices connected to a WLAN. This feature enhances battery life in several ways, compared to the legacy Power Save mode:

• Enhanced Power Saving: VHT TXOP power save allows devices to disable more components of the WLAN transceiver when they are in a low power state. This reduces the power consumption during periods when the device is not actively transmitting or receiving data.
• Intelligent Wake-Up Mechanisms: It employs more sophisticated mechanisms for devices to determine when they need to wake up and listen to the channel, further reducing unnecessary power usage.
• Optimized Operation: This power save mode is optimized for the high-throughput environment of 802.11ac networks, allowing devices to efficiently manage power while maintaining high performance.

Legacy Power Save mode, introduced in earlier versions of the 802.11 standards, does not provide the same level of component disablement or the intelligent wake-up mechanisms found in VHT TXOP power save, making option B the correct answer.

References:

• IEEE 802.11ac-2013 Amendment: Enhancements for Very High Throughput for Operation in Bands below 6 GHz.
• CWNA Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109, by David D. Coleman and David A. Westcott.