CWNP CWNA-108 Exam With Confidence Using Practice Dumps

 The data rate of a signal is the speed that the data bits in individual 802.11 data frames are sent, but it does not account for the actual amount of data that can be transmitted over time. The throughput of a connection is the flow of information over time, which is affected by various factors such as data encoding, modulation, encryption, airtime utilization, noise levels, interference, etc. Therefore, the throughput is always lower than the data rate. According to one of the web search results1, the actual throughput is normally 60-70 percent of the supported data rates. So, for a connection with a data rate of 150 Mbps, the expected throughput would be around 90-105 Mbps.

802.11 QoS is achieved by giving high priority queues a statistical advantage at winning contention. 802.11 QoS is based on the Enhanced Distributed Channel Access (EDCA) mechanism, which defines four access categories (ACs) for different types of traffic: Voice, Video, Best Effort, and Background. Each AC has its own transmit queue and contention parameters, such as Arbitration Interframe Space (AIFS), Contention Window (CW), and Transmission Opportunity (TXOP). These parameters determine how long a station has to wait before transmitting a frame and how long it can occupy the channel. Higher priority ACs have shorter AIFS, smaller CW, and longer TXOP, which means they have more chances to access the channel and send more data than lower priority ACs. However, this does not guarantee that higher priority ACs will always win the contention, as there is still a random backoff process involved. Therefore, 802.11 QoS is a statistical service that provides different levels of service quality based on traffic categories. References: , Chapter 10, page 403; , Section 6.1