474 Chapter 16
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 497). 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
• 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 16-20 shows the 80 ms period display.
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