Motorola Canopy FSK and OFDM radios PTP 100 (FSK) - Manual (Page 39)

Release 11.0 Release Notes and User Guide Supplement
Issue 1, March 2011 Page 39
10 Performance Benchmarking Process
This section describes the performance benchmarking process.
10.1 DEFINITIONS
The following terms are used where these release notes discuss packet processing:
Aggregate Throughput Sum of uplink plus downlink traffic.
Offered Load Test equipment generates a specified load to the Ethernet interface
of a module (SM or the AP). The specifications of the load include
both packet size and packet rate.
Carried Load Test equipment measures the load delivered at the Ethernet interface
of a module. The load is calculated from packet size and number of
packets. As resources are exhausted at any point in the system,
packets may be dropped. The Carried Load equals the Offered Load
minus Dropped Packets.
Downlink/Uplink Load Ratio The ratio of downlink Carried Load to uplink Carried Load.
NOTE: Do not confuse the Downlink/Uplink Load Ratio with the
Downlink Data configuration parameter. The Downlink/Uplink Load
Ratio is determined from the Carried Loads. The Downlink Data is
set by the operator and determines the split of downlink and uplink
slots in the air frame.
10.2 SYSTEM PERFORMANCE AND SYSTEM CONSTRAINTS
Different combinations of system inputs will result in different constraints limiting system
performance.
Larger Packets
With larger packets (the system handles packets up to 1522 Bytes), the system constraint is
airtime, which can also be stated as slots, or maximum bits per second.
This can be calculated as follows:
PMP 100 and PTP 100 Backhauls with 20MHz Channels:
64 Bytes/fragment x 2 fragments/slot x 34 slots/frame x 400 frames/sec x 8 bits/byte = 14 Mbps
This is an aggregate (uplink plus downlink) limit, as the Canopy system is a Time Division Duplex
(TDD) system.
14 Mbps is a typical maximum aggregate throughput for larger packet sizes for an FSK system.
Longer range settings can reduce the number of slots in a frame and packet size (breakage on
64-byte boundaries) can affect packing efficiency (the percentage of fragments fully packed with
64 bytes).
PMP 430 (5.4 and 5.8-GHz OFDM) with 5MHz Channels:
For 1/4 Cyclic Prefix the calculation is
64 Bytes/fragment x 3 fragments/slot x 15 slots/frame x 400 frames/sec x 8 bits/byte = 9.2 Mbps