
Chapter 15 375
W-CDMA Uplink Digital Modulation for Receiver Test
Multiple PRACH Overview
Multiple PRACH Overview
The multiple PRACH feature of the ESG lets you simulate multiple UEs (user
equipment/mobile) attempting to contact a base transceiver station (BTS). This feature is
especially beneficial for BTS overload testing when multiple ESGs are used (see “Overload
Testing with Multiple PRACHs—Multiple ESGs” on page 398). The following is a list of some
of the characteristics you will find in the multiple PRACH feature:
• 80 ms transmission/time period with access slot resolution
• 60 access slots (80 ms / 1.33 ms = 60) numbered 0 to 59
• transmission simulation of eight UEs using independent signatures that automatically
assigns the channel codes in accordance with the 3GPP TS 25.213 V3.7.0 (2001-12)
• transmission of an individual UE’s PRACH multiple times (up to 8 times) within the 80 ms
time period
The number of times a UE’s PRACH can be transmitted is dependent on the number of
access slots each PRACH occupies.
• incorporate AWGN (additive white Gaussian noise) with the multiple PRACH
transmission
• transmit the preamble or the preamble plus the message part
• synchronize multiple ESGs to increase the number of UEs/PRACHs
Understanding the 80 ms Transmission/Time Period
The multiple PRACH feature incorporates an 80 ms time period in which to transmit the
multiple PRACHs/UEs. This 80 ms period has access slot resolution, so it contains 60
selectable access slots (0–59). The entire 80 ms period is transmitted each time, even if only
one access slot is utilized. Within this 80 ms period you have eight available UEs. All eight
can be active at the same time, and each UE has the capability of transmitting its PRACH up
to eight times. Figure 15-20 shows the 80 ms period display.
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