CWNP CWDP-305 Practice Exam Questions & Answers

Explanation Point-to-point bridge links require high-gain directional antennas to maximize signal strength over long distances. An 11 dBi dish antenna provides the necessary gain to cover 1200 meters while minimizing required transmit power. Lower gain antennas would need excessive power output to achieve the same distance. Higher gain options exist but an 11 dBi dish represents the practical balance for this distance.

Explanation This question tests your understanding of filter specifications used in RF design. In-band loss consists of insertion loss and ripple. The maximum in-band loss is 1.5 dB, and ripple is 0.4 dB. Ripple represents the variation within the passband, so the minimum in-band loss is calculated by subtracting half the ripple from the maximum loss. This gives you 1.5 minus 0.4, which equals 1.1 dB. Return loss is a separate measurement that describes reflections and doesn't affect this calculation. Understanding component specifications is essential when selecting equipment for your WLAN design.

Explanation

RTS/CTS is the best protection mechanism for backward compatibility of 802.11n devices with 802.11b devices because it prevents collisions and interference between different modulation types. 802.11n devices use OFDM, while 802.11b devices use DSSS. These two modulation types are not compatible with each other, but they can coexist in the same environment if they use protection mechanisms to avoid overlapping transmissions. RTS/CTS is a protection mechanism that requires a station to send a Request to Send (RTS) frame before transmitting data, and wait for a Clear to Send (CTS) frame from the receiver or the access point. The RTS and CTS frames are sent at a clause 15 (DSSS) or clause 18 (HR/DSSS) rate, which can be understood by both 802.11n and 802.11b devices. The RTS and CTS frames also contain a duration field that indicates how long the data transmission will last. This way, other stations can defer their transmissions until the channel is clear. RTS/CTS reduces the chances of collisions and hidden node problems, and improves the performance and reliability of the wireless network. Reference: CWNP, CWDP Certified Wireless Design Professional Official Study Guide, How 802.11n backward compatibility works

Explanation A spectrum analysis walkthrough identifies interference sources and validates the RF environment before full optimization work begins. This lightweight assessment can be done quickly even when time constraints prevent a comprehensive pre-design survey. It provides essential information about competing signals and channel interference that affects performance.

Explanation IEEE 802.3at supplies maximum 30W per port to each access point. Six APs multiplied by 30W equals 180W total budget needed. This calculation assumes no other powered devices on the switch. Undersizing the PoE budget would cause APs to fail or operate with degraded performance during peak power consumption.

Explanation When new interference appears after deployment, reconfiguring the channel plan allows you to avoid the problematic frequencies and maintain performance. Since the interferer cannot be removed, channel management is the practical solution. Increasing transmit power would only worsen coexistence problems. Relocating APs might help but changing channels is faster and often sufficient.

Explanation 802.11y was a regional standard that operated in the 3.65 to 3.7 GHz band with a maximum transmit power of 20W EIRP. This question tests knowledge of regulatory compliance and spectrum regulations across different regions. When defining specifications, you must understand what frequencies and power levels are available in different geographic areas since this affects both your design choices and equipment selection. The 3.65 to 3.7 GHz band was primarily used in certain countries and represents an important alternative spectrum option for WLAN design professionals to consider during the requirements gathering phase.