User's Manual

Table Of Contents
PMP 400/430 and PTP 200 Series Canopy User Guide
Supplement
Issue 4 0DRAFT 6 November 2009 Page 33 of 64
4 Configuring
Most PMP 400/430 Series and PTP 200 Series configuration items are identical or very similar to
configuration items in standard FSK Canopy modules. This section discusses those that are new
or changed and also remarks on some that remain unchanged.
4.1 LINK OPERATION 1X/2X/3X
PMP 400/430 and PTP 200 Series products offer three levels or speeds of operation 1X, 2X,
and 3X. 3X supports a typical maximum aggregate (sum of up and down) throughput of up to 21
Mbps. If received power is less due to distance between the AP/BHM and the SM/BHS or due to
obstructions, or interference affects the RF environment, the Canopy system will automatically
and dynamically adjust links to the best operation level. Distance, rates and other information
associated with the operation levels are shown in Table 7 on page 26.
The system chooses its operation rate dynamically, based on Canopy’s internal ARQ (Automatic
Repeat reQuest) error control method. With ARQ, every data slot of every frame sent over the air
(except downlink broadcast) is expected to be acknowledged by the receiver, and if
acknowledgement is not received, the data is resent. The sending unit monitors these resends,
and adjusts the operation rate accordingly. A normal system may have links that move from 3X to
2X (or 1X) and back as the RF environment changes. Furthermore, the links operate
independently; normal operation can have a downlink running at 3X while the uplink RF
environment only supports 2X.
The default is for both AP/BHM and SM/BHS to be enabled for 3X operation. An operator may
“lock down” a link to 1X/2X operation or to only 1X operation using the Dynamic Rate Adapt
parameter on the SM’s Configuration => General page as shown in Figure 22. This parameter
locks down both uplink and downlink operation. An operator may lock down an entire sector to 2X
and 1X operation, or to only 1 X operation, using the Dynamic Rate Adapt parameter on the AP’s
Configuration => General page. This parameter locks down uplink and downlink of all links in the
sector, and overrides any SM 1X/2X/3X settings. For example, if an individual link is set for 3X
operation at the SM and the sector is set for 1X operation at the AP, all links in the sector will be
locked down to 1X operation.
Figure 22: Dynamic Rate Adapt on AP "Configuration => General" page
In most cases an operator is well-served to leave the setting at 1X/2X/3X and let the system
automatically and dynamically choose the best rate for each link. Cases when it may be useful to
lock down a link to 1X include
If you are having trouble aiming a link or getting it to register, locking the link down to
2X or 1X may help in some cases.
If the link is suspected to be oscillating between operation rates to the detriment of
throughput, locking the link down may increase throughput. Usually, even if the link is
moving rapidly between operation rates, overall link throughput and sector capacity
are highest if the link is left at 3X and the link can choose its own rate dynamically.
General link troubleshooting