300-425 · Question #317
What is the recommended cell overlap for WLAN design that supports voice traffic?
The correct answer is C. 15%-20%. Voice-optimized WLANs require 15-20% cell overlap to guarantee clients always detect a second AP at sufficient signal strength before their current AP degrades.
Question
What is the recommended cell overlap for WLAN design that supports voice traffic?
Options
- A5%-10%
- B10%-15%
- C15%-20%
- D25%-30%
How the community answered
(34 responses)- A6% (2)
- B3% (1)
- C91% (31)
Why each option
Voice-optimized WLANs require 15-20% cell overlap to guarantee clients always detect a second AP at sufficient signal strength before their current AP degrades.
5-10% overlap is insufficient for voice deployments and risks coverage holes at cell boundaries, causing roaming failures and dropped calls.
10-15% overlap satisfies data WLAN requirements but does not provide the signal margin needed to sustain voice quality through a seamless roaming handoff.
Voice traffic is sensitive to latency and packet loss during roaming, so the recommended design targets a 15-20% cell overlap, corresponding to a minimum received signal of approximately -67 dBm at the cell edge. This overlap ensures a roaming client can initiate a fast handoff to a neighboring AP while still maintaining an acceptable connection to the current one, preventing call drops. Data-only WLANs can tolerate a smaller 10-15% overlap because they are far more resilient to brief coverage gaps.
25-30% overlap is excessive and increases co-channel interference between adjacent APs, degrading aggregate network performance.
Concept tested: WLAN cell overlap percentage for voice roaming design
Source: https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Mobility/vowlan/41dg/vowlan41dg-book/vowlan_ch3.html
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