User Guide
Table Of Contents
- Cambium
- PMP 450 Planning Guide
- Accuracy
- Copyrights
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- Restrictions
- License Agreements
- 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
- Cambium main website: http://www.cambiumnetworks.com/
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- Email support: support@cambiumnetworks.com
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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
Wireless operation
This section describes how the PMP 450 wireless link is operated, including modulation modes, power control
and security.
Time division duplexing
The system uses Time Division Duplexing (TDD) – one channel alternately transmits and receives rather than
using one channel for transmitting and a second channel for receiving. To accomplish TDD, the AP must
provide sync to its SMs. Furthermore, collocated APs must be synced together – an unsynchronized AP that
transmits during the receive cycle of a collocated AP can prevent a second AP from being able to decode the
signals from its SMs. In addition, across a geographical area, APs that can “hear” each other benefit from
using a common sync to further reduce self-interference within the network.
Modules use TDD on a common frequency to divide frames for uplink (orange) and downlink (green) usage, as
shown in the figure below.
For more information on synchronization configuration options, see section Planning for co-location and using
the OFDM Frame Calculator Tool on page 1-100.
Figure 15 TDD Frame Division
OFDM and channel bandwidth
The PMP 450 Series transmits using Orthogonal Frequency Division Multiplexing (OFDM). The channel
bandwidth of the OFDM signal may be configured to 5 MHz (2.4 GHz, 3.5GHz, 3.6 GHz and 5.8 GHz only), 10
MHz or 20 MHz.
Time
pmp-0047 (March 2014)
1-39