Руководство По Проектированию для Cisco Cisco Aironet 350 Mini-PCI Wireless LAN Client Adapter
3-13
Enterprise Mobility 4.1 Design Guide
OL-14435-01
Chapter 3 WLAN Radio Frequency Design Considerations
Planning for RF Deployment
Voice/Deployment
shows the voice network pattern and overlap.
Figure 3-5
Single Floor Site Survey for Voice
The APs are grouped closer together and have more overlap than a data-only installation, because voice
clients should roam to a better AP before dropping packets. You generally also want to run smaller cells
than in the past, and ensure the overlapping cell edges at or above -67 dBm. This accomplishes a number
of things including greater homogeneity across a single cell and reducing processor load in the handheld,
which increases link stability and reduces latency. Although only one AP might be required for a defined
area, Cisco recommends that you have two APs on nonoverlapping channels with a received signal
strength indication (RSSI) above 35 at all times in your installation, for redundancy and load balancing
purposes. For the 7920 voice deployment, Cisco recommends that you have a Received Signal Strength
Indication (RSSI) above 35 at all time in your installation. This is to ensure that the VoIP phone has good
reception as well as allowing some over-subscription and enhances roaming choices for the phone.
clients should roam to a better AP before dropping packets. You generally also want to run smaller cells
than in the past, and ensure the overlapping cell edges at or above -67 dBm. This accomplishes a number
of things including greater homogeneity across a single cell and reducing processor load in the handheld,
which increases link stability and reduces latency. Although only one AP might be required for a defined
area, Cisco recommends that you have two APs on nonoverlapping channels with a received signal
strength indication (RSSI) above 35 at all times in your installation, for redundancy and load balancing
purposes. For the 7920 voice deployment, Cisco recommends that you have a Received Signal Strength
Indication (RSSI) above 35 at all time in your installation. This is to ensure that the VoIP phone has good
reception as well as allowing some over-subscription and enhances roaming choices for the phone.
Remember that designing for low noise background is as important as relatively high energy density
within the cell. This means that a good baseline power setting for the AP is in the 35–50 mW range. This
generally requires approximately 15 percent more APs than if you deployed a coverage model at
100 mW.
within the cell. This means that a good baseline power setting for the AP is in the 35–50 mW range. This
generally requires approximately 15 percent more APs than if you deployed a coverage model at
100 mW.
Pre-site surveys are useful for identifying and characterizing certain challenging areas and potential
sources for interference, such as existing WLANs, rogues, and non-802.11 interference from sources
such as microwave ovens and many cordless telephones. Following a design that should be reviewed and
approved by all stakeholders, post-site surveys should be considered as an excellent audit mechanism to
ensure that the coverage model complies with the intended functional requirements as set forth by the
stakeholders.
sources for interference, such as existing WLANs, rogues, and non-802.11 interference from sources
such as microwave ovens and many cordless telephones. Following a design that should be reviewed and
approved by all stakeholders, post-site surveys should be considered as an excellent audit mechanism to
ensure that the coverage model complies with the intended functional requirements as set forth by the
stakeholders.