How do I test MCS Switching?
Last updated: December 2, 2008
This section is only applicable to the EGPRS lab application.
Observing MCS Switching
It is necessary for you to use the protocol logging capability of the test set to observe the MCS changes. One way to observe this is to use your mobile station as a modem and transfer a file over the air. Transferring something large allows you to more easily observe changes. See
Modem Functional Test with the Data Channel
or
FTP Throughput Test with the Data Channel
for more details. For help setting up the Wireless Protocol Advisor for protocol logging see
Protocol Logging
.
Setup and Activate MCS Switching
This procedure assumes that the BCH parameter for Cell Band is set up correctly for your mobile station and that the appropriate RF IN/OUT Amplitude Offsets have been set to offset loss between the mobile station and the test set. Additionally, this procedure also assumes that the WPA is running and has already established a connection with the test set.
-
Press the
CALL SETUP
key.
-
Press
Operating Mode
(
F1
) and select
Active Cell (EGPRS)
.
-
Select
PDTCH Parameters
(
F9
) from the
Call Parms
menu.
-
Select
Modulation Coding Scheme
(
F11
) from the
PDTCH Parms
menu. The
Modulation Coding Scheme
popup menu appears.
-
Highlight
Downlink Modulation Coding Scheme
and verify that the value is set to
As Uplink
.
-
Scroll to
Uplink Modulation Coding Scheme
and select to change to the value you desire. For example, if you choose MCS-9 and add downlink corruption, the MCS switches to MCS-6 as retransmissions are requested.
-
Press
Close Menu
(
F6
).
-
Press the
More
softkey on the left side of the front panel display to access the
Control
(
2 of 3
) menu.
-
Select
Protocol Control
(
F4
).
-
Select
RLC/MAC
(
F2
).
-
Press the
More
softkey on the left side of the front panel display to access the
RLC/MAC Ctrl
(
2 of 2
) menu.
-
Select
Retransmission MCS Switching
(
F1
). The
Retransmission MCS Switching
popup menu appears.
-
Select
Allow MCS Switching
and select
On
.
-
Select
Retransmissions before MCS switch
and enter
2
. This forces the test set to switch the MCS when a block the mobile station requests retransmission of the same block twice.
How to Setup Corruption of Downlink Blocks
To force the mobile station to request retransmission of blocks and therefore force the test set to switch to a more robust MCS, you can set up the deliberate corruption of downlink blocks.
-
Press the
CALL SETUP
key.
-
Press the
More
softkey on the left side of the front panel display to access the
Control
(
2 of 3
) menu.
-
Select
Protocol Control
(
F4
).
-
Select
Layer 1
(
F1
).
-
Select
PDTCH Downlink Corruption
(
F1
). The
Downlink Corruption
popup menu appears.
-
Select
Downlink Corruption
and select
On
. Parameters for configuring the downlink corruption appear. See
Downlink Corruption
for more information.
How to View the Downlink Corruption Blocks in the Wireless Protocol Advisor (WPA)
This procedure assumes that the BCH parameter for Cell Band is set up correctly for your mobile station and that the appropriate RF IN/OUT Amplitude Offsets have been set to offset loss between the mobile station and the test set.
-
Setup the Downlink Corruption parameters on the test set. See
How to Setup Corruption of Downlink Blocks
for more details.
-
Configure the WPA test set filter to filter the Layer 1 Information protocol.
-
Start the WPA. See
How to use Protocol Logging
for more details.
-
Press Start Data Connection (F3).
-
Stop the WPA. See
How to use Protocol Logging
for more details.
-
View the message decode for Downlink Frame Integrity messages (for Layer 1 Protocol). The figure below is an example of a Downlink Frame Integrity message.
.
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