Cisco Systems 71642 manual Signal Reflection Caused by a Wall

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Figure 20 shows the signal propagation caused by the wall on which the access point is mounted.

Figure 20￿Signal Reflection Caused by a Wall

The preceding examples also apply when you place access points and antennas in or near the ceiling in a standard Enterprise environment. If there are metal air ducts, elevator shafts, or other physical barriers that can cause signal reflection or multipath interference, Cisco highly recommends that you move the antennas away from those barriers. In the case of the elevator, move the antenna a few feet away in order to help eliminate the signal reflection and distortion. The same is true with air ducts in the ceiling.

A survey conducted without sending and receiving packets is not sufficient. The I−beam example shows the creation of null points that can result from packets that have CRC errors. Voice packets with CRC errors are missed packets that adversely affect voice quality. In this example, those packets could be above the noise floor measured by a survey tool. Therefore, it is very important that the site survey not only measures signal levels but also generates packets and then reports packet errors.

Figure 21 shows a Cisco AP1200 properly mounted to a ceiling T−bar, with the antennas in an omni−directional position.

Figure 21￿Cisco AP1200 Mounted to a Ceiling

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Contents Document ID Deployment ScenariosIntroduction PrerequisitesExecutive Summary Requirements Components UsedVocera Solution Vocera Badge OverviewVocera Call Capacity Considerations Vocera Communications Server CapacityVoceras Infrastructure Planning Architecture OverviewMulticast in an Lwapp Deployment Unicast−Multicast Delivery MethodMulticast−Multicast Delivery Method Lwapp Multicast−MulticastEnable IP Multicast Routing Router and Switch Multicast ConfigurationEnable PIM on an Interface Deployment Scenarios Disable Switch Vlan Igmp SnoopingMulticast Enhancements in Version 4.0.206.0 and Later Single Controller in Multicast−Multicast Mode Single Controller DeploymentMultiple Controller Layer 2 Deployment Multiple Controller Layer 3 DeploymentVoWLAN Deployments Ciscos Reccommendations Construction Methods and MaterialsInventory Security Mechanisms Supported Leap ConsiderationsVoice, Data and Vocera VLANs Wireless Network InfrastructureNetwork Sizing Deployments and Configuration Switch RecommendationsBadge Configuration Tune AutoRF for Your Environment ∙ How do I know if the tranmit power is too hot or too cold? Wireless Network Infrastructure Configuration Create InterfacesWireless−Specific Configuration Create the Vocera Voice InterfaceWlan Configuration Wlan ConfigurationConfigure Access Point Detail AP DetailConfigure the 802.11b/g Radio Wireless IP Telephony Verification Association, Authentication, and Registration Common Roaming Issues Badge Loses Voice Quality while RoamingAudio Problems Registration and Authentication ProblemsOne−sided Audio Choppy or Robotic AudioAP and Antenna Placement Appendix aSignal Reflection Caused by a Wall Cisco Aironet 5959 Antenna Mounted to a Ceiling Signal−to−Noise Ratio SNR Interference and Multipath DistortionNetPro Discussion Forums − Featured Conversations Signal AttenuationRelated Information
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