User Guide
Table Of Contents
- Cambium
- PMP 450 Planning Guide
- Accuracy
- Copyrights
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- Restrictions
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- High Risk Materials
- Safety and regulatory information
- Contents
- List of Figures
- List of Tables
- About This Planning Guide
- PMP support website: http://www.cambiumnetworks.com/support
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- Address:
- Chapter 1: Planning considerations
- Regulatory planning
- Network migration planning
- Site planning
- Link planning
- Analyzing the RF Environment
- Selecting Sites for Network Elements
- Diagramming Network Layouts
- Grounding and lightning protection
- Configuration options for TDD synchronization
- Data network planning
- Security planning
- Isolating APs from the Internet
- Managing module access by passwords
- Filtering protocols and ports
- Port Lockdown
- Isolating SMs
- Filtering management through Ethernet
- Allowing management from only specified IP addresses
- Configuring management IP by DHCP
- Planning for airlink security
- Planning for RF Telnet Access Control
- Forwarding Downlink PPPoE PADI packets
- Planning for RADIUS integration
- Planning for SNMP security
- Ordering components
- Chapter 2: Legal information
- Cambium Networks end user license agreement
- Acceptance of this agreement
- Definitions
- Grant of license
- Conditions of use
- Title and restrictions
- Confidentiality
- Right to use Cambium’s name
- Transfer
- Updates
- Maintenance
- Disclaimer
- Limitation of liability
- U.S. government
- Term of license
- Governing law
- Assignment
- Survival of provisions
- Entire agreement
- Third party software
- Hardware warranty
- Limit of liability
- Cambium Networks end user license agreement
- Chapter 3: Reference information
PMP 450 Planning Guide
Anticipating Reflection of Radio Waves
In the signal path, any object that is larger than the wavelength of the signal can reflect the signal. Such an
object can even be the surface of the earth or of a river, bay, or lake. The wavelength of the signal is
approximately
• 2 inches for 2.4, 3.5GHz, 3.6 GHz, 5.4-GHz and 5.8-GHz signals.
A reflected signal can arrive at the antenna of the receiver later than the non-reflected signal arrives. These two
or more signals cause the condition known as multipath. Multipath may increase or decrease the signal level
and so overall attenuation may be higher or lower than that caused by the link distance. This is problematic at
the margin of the link budget, where the standard operating margin (fade margin) may be compromised.
Noting Possible Obstructions in the Fresnel Zone
The Fresnel (pronounced fre∙NEL) Zone is a three-dimensional volume around the line of sight of an antenna
transmission. Objects that penetrate this area can cause the received strength of the transmitted signal to fade.
Out-of-phase reflections and absorption of the signal result in signal cancellation.
The foliage of trees and plants in the Fresnel Zone can cause signal loss. Seasonal density, moisture content of
the foliage, and other factors such as wind may change the amount of loss. Plan to perform frequent and
regular link tests if you must transmit though foliage.
pmp-0047 (March 2014)
1-97