Redline Communications Inc. AN100UA 用户手册
Red
MAX
™
Base Station
User Manual
Doc. #70-00058-01-01
Proprietary Redline Communications © 2007
July 13, 2007
Page 94 of 119
conjunction with adaptive equalization, coding, and modulation, use of the guard interval
provides reliable operation in a wide class of non line-of-sight environments.
provides reliable operation in a wide class of non line-of-sight environments.
6.4.2 Calculating Receive Sensitivity (WiMAX Testing)
Overview
The WiMAX test for receive sensitivity modifies the methodology from 802.16 to allow
results to be obtained easier and faster. The standard Bit Error Rate (BER) of 1x10-6
remains the benchmark for these calculations. The BER is obtained by measuring Packet
Error Rate (PER), but PER cannot truly be measured (it is a limit) and requires that a test
be performed to estimate the PER value. Larger sample sizes will produce more accurate
values for PER. There is a practical limit to the size of the test sample, and WiMAX has
chosen the number of packets in the sample to enable result that will approximate a BER
lower than 1x10-6.
results to be obtained easier and faster. The standard Bit Error Rate (BER) of 1x10-6
remains the benchmark for these calculations. The BER is obtained by measuring Packet
Error Rate (PER), but PER cannot truly be measured (it is a limit) and requires that a test
be performed to estimate the PER value. Larger sample sizes will produce more accurate
values for PER. There is a practical limit to the size of the test sample, and WiMAX has
chosen the number of packets in the sample to enable result that will approximate a BER
lower than 1x10-6.
Sample Test for Subscriber Receive Sensitivity
1. Connect packet generator to the base station-to-subscriber link and then configure
packet generator to send 50,000 Ethernet packets with payload of 288 Bytes (i.e.,
total Ethernet packet size is 288 + 18 = 306 Bytes). Payload should not be chosen by
the packet generator, but must be filled with the pattern defined in the WiMAX
standard. The packets should be sent at a rate to fill at least 80% of the downlink
(DL) frame.
total Ethernet packet size is 288 + 18 = 306 Bytes). Payload should not be chosen by
the packet generator, but must be filled with the pattern defined in the WiMAX
standard. The packets should be sent at a rate to fill at least 80% of the downlink
(DL) frame.
2. Count the number of packets received. If less than 97 packets are lost, it can be
stated with 95% confidence that the BER is 1x10-6 or lower.
3. Repeat the test by sending 20,000 Ethernet packets with payload of 864 Bytes. If less
than 118 packets are lost, it can be stated with 95% confidence that the BER is 1x10-
6 or lower.
6 or lower.
4. You repeat the test by sending 10,000 Ethernet packets with payload of 1488 Bytes.
If less than 100 packets are lost, it can be stated with 95% confidence that the BER is
1x10-6 or lower.
1x10-6 or lower.
5. Receiver sensitivity is defined as the lowest RSSI value tested where samples for all
three packet sizes did not exceed the maximum number of lost packets. The 95%
confidence level indicates that if the test is repeated multiple times, you will obtain
passing results 95 times out of 100.
confidence level indicates that if the test is repeated multiple times, you will obtain
passing results 95 times out of 100.
Refer to the following table for a summary of the test parameters.