signalled values of these gain offsets must be divided by 15 to obtain the actual

values. The signalled values can range from 0 to 15. Either the data branch or the control branch must

have a signalled value of 15. In this example, the first transport format has a control branch gain

offset of 12/15 and a data branch gain offset of 15/15. This indicates that the data branch is

transmitted with 1.9 dB more power than the control branch, i.e. power difference ¼ 10 _ log(152/

122). The second transport format has a control branch gain offset of 11/15 and a data branch gain

offset of 15/15. This indicates that the overhead generated by the control branch decreases as the bit

rate of the data branch increases. The log file also specifies the power offset to be applied between the

acknowledged PRACH preamble and the control part of the PRACH message. This power offset can

be configured to have any integer value between _5 and 10dB. In this example, both transport

formats have a power offset of 2 dB. Table 3.24 presents a set of example transmit powers for the

gain offsets specified in Log File 3.9 assuming that the acknowledged PRACH preamble had a

transmit power of 5 dBm. These figures illustrate that the transport format with the higher bit rate

makes use of a higher total transmit power although the transmit power allocated to the control

branch remains constant. RACH

TFI 0 TFI 1 CCCH, DCCH DTCH RACH TFI 0 TFI 1 CCCH, DCCH DTCH RACH TFI 0 TFI 1 Transport Format Combination 2 (CTCF = 1)