The system implications of such a service go beyond the CELL-DCH radio resource connected
state and into the CELL-FACH, CELL-PCH and URA-PCH states as well, especially when
HS-DSCH capability is present.
As shown in Fig. 9.15, where we described the physical channels involved in the CPC mode, it
was required to define a new UL-DPCCH slot format. In this case only pilot and transmit power control
(TPC) bits will be transmitted in the UL-DPCCH.
The UE is placed into CPC mode through signaling on the HS-SCCH and hence the UE begins
transmitting the UL-DPCCH with a new time slot format described above. The new slot format
should be configured by the RNC in order to potentially avoid blind slot format detection in the nonserving
NodeBs.
In this case, it is important to clearly define the mechanisms to be used to detect the standard end of
the total silence period. In order to help with the data channel re-activation, preambles are transmitted
to help the NodeB with this transition. The 3GPP standard defines DTX cycle periods and various modes
the UE must check in order to determine if the UL-DPCCH is allowed to be transmitted. For example,
E-DCH and UL-DPCCH are always time slot aligned on the uplink whereas the HS-DPCCH may not
be due to transmission time offsets.
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