An engineer has performed a predictive site survey for high-speed data and voice in an indoor office. What is the recommended data rate with גˆ’67 dBm signal level for optimal VoWLAN design?
An engineer has performed a predictive site survey for high-speed data and voice in an indoor office. What is the recommended data rate with גˆ’67 dBm signal level for optimal VoWLAN design?
In designing a VoWLAN (Voice over WLAN) system, special considerations need to be taken to ensure optimal performance. The recommended data rate for voice or real-time application support typically starts at 12 Mbps, which balances reliable throughput with the need to minimize latency and jitter. The 24 Mbps data rate is generally more appropriate for real-time video applications rather than just voice. Therefore, for optimal VoWLAN design, 12 Mbps on 802.11 an provides a good balance as the lowest mandatory data rate while avoiding overcrowding and ensuring efficient use of the 5 GHz band which is less crowded than the 2.4 GHz band.
Answer is C. - CCNP official guide, Chapter 5, Section Designing a Wireless Network for Voice and Video: A better approach is to limit transmissions to use higher data rates so that stations transmit a frame and get off the air sooner, allowing other stations an opportunity to use the channel. That ultimately affects latency and jitter—parameters that are critical for acceptable voice and video performance. You should configure 12Mbps as the lowest and only mandatory data rate, while disabling all rates below that. All data rates greater than 12Mbps should be configured as supported so that they can be used by any device and application as RF conditions permit. - 802.11b supports max 11 Mbps.
C - ‘For voice or real-time application support, 12Mbps is common, and 24Mbps is expected if real-time video applications (for example, video conferencing) are your target. Here again, as most cells carry both data and voice, designing around 12Mbps minimum has become common even for data-only support, in anticipation of occasional voice activity.’ Official Cert Guide, Ch.3. p.60. para.3.‘As you plan the band and channel assignment for each AP, try to leverage the 5GHz band as much as possible.’ Official Cert Guide, Ch.5. p.106. para.4.‘You should configure 12Mbps as the lowest and only mandatory data rate, while disabling all rates below that.’ Official Cert Guide, Ch.5. p.107. para.2.
Official CCNP book page 60: For basic data coverage, 6Mbps is common. For voice or real-time application support, 12Mbps is common, and 24Mbps is expected if real-time video applications (for example, video conferencing) are your target. Here again, as most cells carry both data and voice, designing around 12Mbps minimum has become common even for data-only support, in anticipation of occasional voice activity. So the answer is C
found this on Cisco's VoWLAN guide...I think the answer should be D "Because the 2.4 GHz band is so crowded, and coupled with constraints on its channel allocation, Cisco recommends using the 5 GHz Wi-Fi band for new VoWLAN deployments" https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-5/Enterprise-Mobility-8-5-Design-Guide/Enterprise_Mobility_8-5_Deployment_Guide/Chapter-9.html
If it weren't for the question throwing "high-speed" and "optimal" in there, I would say 12Mbps, which is definitely the minimum specification. However, I believe they are looking for 24Mbps.
Source - https://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob30dg/Voice.pdf "For a high density deployment or a deployment where a large number of calls are required in a small floor space, 11a is recommended because of the number of channels and the 54 Mbps data rate. The lower data rates in 11a can be disabled, the 24 Mbps data rate can be set to “required”, and the rates of 36 to 54 can be left enabled. "
I think the answer is D. I found this in the VoWLAN Design recommendations: Coverage cells can be created for specific data rates. For a high density deployment or a deployment where a large number of calls are required within a small floor space, 802.11a is recommended because of the number of channels and the 54 Mbps data rate. The lower data rates in 802.11a can be disabled, the 24 Mbps data rate can be set to required, while the 36 to 54 Mbps data rates can be left enabled.
i will go for C - because there are asking - What is the recommended data rate withגˆ’-67 dBm signal level for optimal VoWLAN design? - -67dBm should be edge so there should be the lowest enabled data rate 12Mbps
It's definitely answer C In voice and video design you should configure 12 Mbps as the lowest and only mandatory data rate.
when designing for voice, you have to think about RTP streams. from cisco study guide: (an now you can choose C or D) " voice calls use bidirectional RTP streams to transport audio. Each call uses two separate streams, but they cannot be transmitted simultaneously because of channel contention. At a 24Mbps data rate, up to 27 simultaneous bidirectional RTP streams can exist, or up to 13 calls."
I would sayt "it depends" of the number of simultaneous call to place
How is the answer B? Since the maximum data rate of 802.11b is 11Mbps, the answer cannot be 24Mbps on 802.11bgn
I think that by b/g/n it means 2.4GHz as a whole... With 802.11n, it can go higher than 24Mbps. I'm still not sure how it's B. though.
"The lower data rates in 11a can be disabled, the 24 Mbps data rate can be set to “required”, and the rates of 36 to 54 can be left enabled. " https://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob30dg/Voice.pdf
the right answer is c because at 24mbs 802.11b cannot scale and your adviced to stick to the 5ghz band which gives us 12mbs for voice and 24mbs for video
Provided answer is correct, the question involves a predictive site survey requirements, there are current and legacy VoWLAN environments that can utilize b with the overlapping channels for voice, however not recommended, but is important for predictive survey purposes. Here is the Cisco white page link ref. chapter 11-12. https://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob30dg/Voice.pd
VoWLAN. min -67dbm and 12 Mbps
answer is A, please check the data rate. We traditionally use 2.4ghz to do the predicative, and 802.11b only have11 mbps, therefore, A is answer.
C is correct .
Need to correct my previous answer, I say D is correct , 12Mbps is the minimum rate but to having better voice and more call we need higher data rate, while using low data rate we use more airtime of each channel . 24 Mbps minimizes airtime usage, supports more simultaneous calls, and ensures lower latency and jitter.
Also the text from official guide is talking about lowest mandatory data rate which is 12Mbps but the question is asking about Optimal situation
You should configure 12Mbps as the lowest and only mandatory data rate, while disabling all rates below that.