5.4 Discontinuous transmission (DTX) procedure

25.2243GPPPhysical layer procedures (TDD)TS

The DTX procedure shall be applied for CCTrCHs mapped to S-CCPCH, UL DPCH, DL DPCH, PUSCH and PDSCH, if the total bit rate of the CCTrCH differs from the total channel bit rate of the physical channels allocated to this CCTrCH.

Rate matching is used in order to fill resource units completely, that are only partially filled with data. In the case that after rate matching and multiplexing no data at all is to be transmitted in a resource unit the complete resource unit shall be discarded from transmission (DTX), unless a Special Burst is transmitted in the RU. This applies also to the case where only one resource unit is allocated and no data has to be transmitted.

The special burst is transmitted in both consecutive subframes (subframe#1 and #2). SS Bits may be transmitted in Special Bursts.for each CCTrCH mapped to UL DPCH, DL DPCH, PUSCH and PDSCH physical channels.

5.4.1 Description of special bursts

For S-CCPCH, UL DPCH, DL DPCH, PUSCH and PDSCH, the Special Burst has the same timeslot format as the burst used for data provided by higher layers. If the timeslot format contains a TFCI field, then the TFCI field shall be filled with "0" bits. The Special Burst may also carry layer 1 control symbols such as TPC bits for the purposes of inner-loop power control. The data portions of the Special Burst are filled with an arbitrary bit pattern.

For S-CCPCH, DL DPCH, PUSCH and PDSCH, the transmission power of the special burst shall be the same as that of the substituted physical channel of the CCTrCH. For UL DPCH, if the gain factor of the zero rate TFC is explicitly signalled by high layer, the transmission power of the special burst shall be weighted by the gain factor  of the zero rate TFC [refer 5.1.1.4.1], otherwise the transmission power of the special burst shall be the same as that of the substituted physical channel of the CCTrCH. In the case of uplink physical channels where autonomous spreading factor change by the UE is permitted by higher layers, the substituted physical channel is considered to be that which would have been employed for the lowest non-zero rate TFC within the set of allowed TFC’s and the transmission power of the Special Burst shall again correspond to that of the physical channel substituted.

5.4.2 Use of special bursts during DTX

In the case that after link establishment there are no transport blocks provided for transmission by higher layers for a given CCTrCH mapped to UL DPCH, DL DPCH, PUSCH or PDSCH physical channels, then a Special Burst shall be transmitted in the first allocated frame of the transmission pause. If, including the first frame, there is a consecutive period of Special Burst Period (SBP) frames without transport blocks provided by higher layers, then another special burst shall be generated and transmitted at the next possible frame. This pattern shall be continued until transport blocks are provided for the CCTrCH by the higher layers. SBP shall be provided by higher layers. The value of SBP shall be independently specified for uplink and for downlink and shall be designated as

SBGP (special burst generation period) for uplink transmissions

SBSP (special burst scheduling parameter) for downlink transmissions

The default value for both SBGP and SBSP shall be 8.

If DTX is applied on S-CCPCH carrying MBSFN FACH, special burst shall be sent in the first radio frame of each associated TTI.

The Special Burst shall be transmitted using the physical channel with the lowest physical channel sequence number (p) as defined by the rate matching function in [9].

5.4.3 Use of special bursts for initial establishment / reconfiguration

Upon initial establishment or reconfiguration for either 160 ms following detection of in-sync, or until the first transport block is received from higher layers, both the UE and the Node B shall transmit the special burst for each CCTrCH mapped to UL DPCH, DL DPCH, PUSCH and PDSCH physical channels.

The Special Burst shall be transmitted using the physical channel with the lowest physical channel sequence number (p) as defined by the rate matching function in [9].