User Guide
Table Of Contents
- Cambium
- PMP 450 Planning Guide
- Accuracy
- Copyrights
- 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/
- Sales enquiries: solutions@cambiumnetworks.com
- Email support: support@cambiumnetworks.com
- Cambium Networks
- 3800 Golf Road, Suite 360
- Rolling Meadows, IL 60008
- Chapter 1: Product description
- Chapter 2: 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
- Planning for RADIUS integration
- Planning for SNMP security
- Ordering components
- Chapter 3: 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 4: Reference information
Wireless operation Product description
1-14
pmp-0047 (December 2012)
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 Figure 9.
For more information on synchronization configuration options, see section Planning for co-location and using the
OFDM Frame Calculator Tool on page 2-23.
Figure 9 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 10 MHz or 20 MHz.
Time