490 Chapter 16
W-CDMA Uplink Digital Modulation for Receiver Test
Setting Up a Multiple PRACH Signal
Configuring the PRACH Timing Setup
In this procedure you will learn how to enable multiple UEs/PRACHs and align them within the access slots.
You have eight available UEs that can span an 80 ms time period (60 access slots numbered 0 to 59). The
UEs can be configured so their PRACHs occupy the same or different access slot(s) relative to other UEs.
Each UE can also be configured to transmit its PRACH up to eight times using different access slots.
NOTE The number of times a single UE can transmit its PRACH within the 80 ms time period is
constrained by the number of access slots a single PRACH occupies. If the UE retransmits
in a timeslot that is occupied by one of its previous PRACH transmissions, the
retransmission does not occur.
However you will have to turn the message part off to achieve the maximum number of individual UE
PRACH transmissions.
All eight UEs can be active at the same time and each can have a different or the same signature assignment.
For more information on understanding the PRACH Timing Setup display, see “Understanding the 80 ms
Transmission/Time Period” on page 474.
Accessing the PRACH Timing Setup Display
Press
Link Control > PhyCH Setup > PRACH Timing Setup.
This takes you into the table editor where you can set the number of UEs for transmitting multiple PRACHs.
For the factory default setting, UE1 is on and the starting access slot in position one for all UEs is zero.
The parameters set in this table apply to the UE selected, unlike the other setup displays where the
parameters apply to all eight UEs.
For the following tasks, we will work with three UEs. This will demonstrate how different UEs can occupy
the same access slots, and how to repeat/retransmit a UE’s PRACH.
Figure 16-32 on page 494 shows a graphical representation of the multiple PRACH transmission as
configured by this procedure, while Figure 16-33 on page 496 displays the same signal configuration on the
E4440A PSA.
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