,n The scrambling code application aligns with the radio frames, i.e. the first scrambling chip corresponds to the beginning of a radio frame. Table 4.9 The Quantization of the Gain Parameters Signalling values for Bc and Quantized amplitude ratios BC and Bd 0.9333 0.8666 0.8000 0.7333 0.6667 0.6000 0.5333 0.4667 0.4000 0.3333 0.2667 0.2000 0.1333 0.0667 Switch off 4.3.3 Common Uplink Physical Channels 4.3.3.1 Physical Random Access Channel - PRACH The PRACH carries the Random Access Channel (RACH). radio frame: 10 ms radio frame: 10 ms 5120 chips Access slots Random Access Transmission Random Access Transmission Random Access Transmission Random Access Transmission Figure 4.5 RACH access slot numbers and spacing. The UTRA Physical Layer Design 4.3.3.1.1 The Random-access Transmission Structure The random-access transmission uses a slotted ALOHA technique with fast acquisition indication. The UE can start the random-access transmission at the beginning of a num- ber of well-defined time intervals, denoted access slots as illustrated in Figure 4.5. There are 15 access slots per two frames and they are spaced 5120 chips apart. The in- formation about the type of access slots available for random-access transmission comes from the upper layers. Figure 4.6 illustrates the random-access transmission structure, where the transmission consists of one or several preambles of length 4096 chips and a message of length 10 ms or 20 ms. Each preamble has 256 repetitions of 16 chips signature. Thus, there is a maximum of 16 available signatures, see [4] for more details. 10 ms (1 radio frame) Preamble Preamble Preamble Message part 4096 chips Message part 20 ms (two radio frames) Figure 4.6 Structure of the random-access transmission. 4.3.3.1.2 The RACH Message Part Figure 4.7 illustrates the random-access message part radio frame structure, where the 10 ms message part radio frame is split into 15 slots, each having a length Tslot = chips. Furthermore, each slot consists of two parts, i.e. a data part to which the RACH transp