Question 42 of 240 from exam 400-351: CCIE Wireless Written Exam

Question 42 of 240 from exam 400-351: CCIE Wireless Written Exam


You are tasked with creating a controller-based high-density RF design.

Which three factors determine the cell size? (Choose three.)



A. B. C. D. E. F.


When designing a high-density RF network, it is essential to consider the cell size, which is the area covered by a single AP or a group of APs. Here are the three main factors that determine the cell size:

  1. AP Placement The placement of APs plays a crucial role in determining the cell size. APs should be positioned optimally to provide adequate coverage and capacity to the clients in the coverage area. The AP placement should be based on the building layout, density of clients, and RF obstacles. APs should be installed in such a way that they don't interfere with each other, leading to channel overlap and co-channel interference.

  2. Basic Data Rate The basic data rate is the lowest data rate that the AP transmits to the clients. It determines the maximum distance that the signal can travel before it becomes too weak to be received. Lower data rates can travel farther but at the expense of throughput. Higher data rates provide better throughput but have limited coverage. Hence, the basic data rate should be set according to the distance between the APs and the clients and the required throughput.

  3. Free Space Path Loss Free space path loss (FSPL) is the attenuation of radio waves as they propagate through space. It is caused by factors such as distance, frequency, and obstacles in the path. The FSPL limits the range of the APs and determines the cell size. Higher frequency signals suffer more significant losses due to the shorter wavelength. The FSPL can be calculated using various tools, such as online calculators, to determine the cell size based on the required coverage and signal strength.

Note that the other options listed in the question are also relevant to RF design, but they do not directly affect the cell size. Antenna type and ClientLink support affect the antenna gain and client connectivity, respectively, while the TPC threshold setting controls the transmit power of the APs to maintain optimal coverage and reduce interference.