Redline Communications Inc. AN100UXA 用户手册
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AN-100U/UX Base Station
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Proprietary Redline Communications © 2010
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April 19, 2010
OFDM equalization and coding techniques cannot overcome all forms of sharp,
multipath-related fading. For additional robustness, the OFDM implementation uses a
guard interval between each of the sub-channels. This guard interval is filled with
redundant data taken from the end of the same channel symbol and repeated at the
beginning of each channel symbol. Multipath echoes from each individual sub-channel
overlap the guard interval, rather than overlapping data in other symbols. Used in
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.
multipath-related fading. For additional robustness, the OFDM implementation uses a
guard interval between each of the sub-channels. This guard interval is filled with
redundant data taken from the end of the same channel symbol and repeated at the
beginning of each channel symbol. Multipath echoes from each individual sub-channel
overlap the guard interval, rather than overlapping data in other symbols. Used in
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.
7.5.3 Calculating Receive Sensitivity (WiMAX Testing)
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.
1x10-6 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.
is 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.
Table 60: Op Notes: Receive Sensitivity Tests (95% Confidence)
Equivalent BER
Packets Sent
Payload Size
Max. Packets Lost
10,000
1,488
100
1x10-6
20,000
864
118
50,000
288
97
60,000
1,488
57
1x10-9
100,000
864
55
300,000
288
100