Chapter 1: Product description
Wireless operation
Page 1-26
Using frequency planning
Networks will benefit from the use of fixed channel allocations if (a) the network consists of
multiple PTP links, and (b) RF interference predominantly arises from equipment in the same
network.
Frequency planning is the exercise of assigning operating channels to PTP units so as to
minimize RF interference between links. Frequency planning must consider interference from
any PTP unit to any other PTP unit in the network. Low levels of interference normally allow for
stable operation and high link capacity.
The frequency planning task is made more straightforward by use of the following techniques:
•
Using several different channels
•
Separating units located on the same mast
•
Using high performance (directional) external antennas
Synchronized networks
TDD synchronization can be used to relax constraints on the frequency planning of PTP
networks. Synchronization has the following benefits:
•
Allows tighter frequency re-use, and thus wider channel bandwidth.
•
Allows more convenient collocation of units on a single mast.
•
Allows use of smaller or lower performance antennas.
•
Reduces inference, resulting in use of more efficient modulation modes.
In a correctly designed synchronised network, all links are configured with the same TDD frame
duration, and the TDD frame contains guard periods longer than the propagation delay
between the most distant interfering units.
Each synchronized unit is assigned to one of two phases. A master ODU can be assigned to
either phase. A slave ODU must be assigned to a different phase from the associated master
ODU. The phase is set by suitable configuration of TDD Frame Offset.
TDD synchronization eliminates RF interference between units in the same phase. This means
that frequency planning in a synchronized network is concerned only with interference
between units in different phases. Frequency planning is still necessary, but the number of
potential interference paths to be considered is halved. Frequency planning in a synchronized
TDD network has approximately the same level of complexity as frequency planning in a
Frequency Division Duplex (FDD) network.
Further reading
For information about…
Refer to…
How to plan networks
, or contact your
Cambium distributor or re-seller.
TDD synchronization
PTP 670 supports three hardware options for TDD Synchronization:
Содержание PTP 670 Series
Страница 1: ...F Cambium PTP 670 Series User Guide System Release 670 02 50 ...
Страница 349: ...Chapter 5 Installation Installing an SFP Ethernet interface Page 5 52 Correct Incorrect ...
Страница 405: ...Chapter 6 Configuration and alignment System menu Page 6 46 Figure 151 LAN Configuration page PTP topology TDM support ...
Страница 406: ...Chapter 6 Configuration and alignment System menu Page 6 47 Figure 152 LAN Configuration page PTP topology SFP support ...
Страница 408: ...Chapter 6 Configuration and alignment System menu Page 6 49 Figure 154 LAN Configuration page HCMP topology ...
Страница 416: ...Chapter 6 Configuration and alignment System menu Page 6 57 Figure 156 QoS Configuration page IP MPLS ...
Страница 445: ...Chapter 6 Configuration and alignment Management menu Page 6 86 Figure 173 Time Configuration page SNTP enabled ...
Страница 551: ...Chapter 7 Operation System statistics Page 7 64 Figure 250 Main Port Counters page when main port is bridging traffic ...