15 HS-DSCH reception in CELL_PCH and URA_PCH states (FDD only)

25.3083GPPHigh Speed Downlink Packet Access (HSDPA)Overall descriptionRelease 17Stage 2TS

The HS-DSCH reception in CELL_PCH and URA_PCH state is enabled by the UTRAN by including the parameters for HS-DSCH reception in CELL_PCH and URA_PCH state in the system information broadcast Parameters include PICH, HS-SCCH, and HS-DSCH configuration used in CELL_PCH and URA_PCH state. The HS-DSCH reception in CELL_PCH and URA_PCH state supports discontinuous reception as when DRX is used the UE needs only to monitor one Page Indicator, PI, in one Paging Occasion per DRX cycle.

When HS-DSCH reception is enabled in the cell, it shall take precedence instead of reception of S-CCPCH and PCH for paging messages in CELL_PCH and URA_PCH states.

In CELL_PCH state the HS-DSCH is used to enable the reception of BCCH, DCCH, DTCH and PCCH logical channel data. In URA_PCH state the HS-DSCH is used to enable the reception of PCCH logical channel data.

UTRAN obtains the knowledge of the UE supporting the reception of HS-DSCH in CELL_PCH and URA_PCH state from the RRC Connection Setup Complete message and the URA update message.

When the HS-DSCH reception in CELL_PCH is enabled, the UTRAN can configure the UEs to store the C-RNTIs and dedicated H-RNTIs when performing reconfiguration to CELL_PCH.

For UEs with stored C-RNTI and dedicated H-RNTI, the network should use the stored dedicated H-RNTI to transmit DCCH and DTCH to the UE. When UE receives the dedicated H-RNTI on HS-SCCH, the UE shall initiate actions on measurement reporting on RRC as defined in subclause 14.2. When UE has uplink data to transmit, UEs shall initiate the measurement reporting on RRC as defined in subclause 14.2. The UE shall use the stored C-RNTI to transmit DTCH and DCCH without first performing the Cell Update procedure.

If UTRAN has not configured the UE to store the C-RNTI and H-RNTI in CELL_PCH the UTRAN should send paging message on PCCH mapped on HS-DSCH by HS-PDSCH code and transport block sizes broadcasted in system information. One HS-PDSCH code, maximum two transport block sizes and the number of PCCH transmissions (n) are broadcasted in system information.

In CELL_PCH state, when the UE is configured with a dedicated H-RNTI, the UE is required to monitor the dedicated H-RNTI and BCCH specific H-RNTI on the configured set of 5 associated HS-SCCHs subframes after the paging indication is sent on the PICH. In CELL_PCH state, when the UE is not configured with a dedicated H-RNTI, or in URA_PCH state, the UE is required to monitor the HS-PDSCH code after paging indication on PICH.

The BCCH is mapped on HS-DSCH for transmitting system information change information. The transmission of BCCH on HS-DSCH is performed by using BCCH specific H-RNTI on specific HS-SCCH code indicated in system information broadcast.

The UE in CELL_PCH and URA_PCH states receiving HS-DSCH performs normal cell reselection process. The inter frequency and inter RAT cell reselection is supported as previous releases. When UE enters to a new cell, it obtains the valid HS-SCCH configuration from system information broadcast and performs Cell Update procedure.

The HS-DSCH reception in CELL_PCH and URA_PCH state utilizes the enhanced L2 architecture with flexible RLC PDU size and MAC-ehs segmentation as defined in clause 6 and in [7].

15.1 UE operation

When HS-DSCH reception is configured in the system information broadcast, the UE shall after receiving a paging indication on PICH for its specific paging group, perform the following:

In CELL_PCH state, when the UE is not configured with a dedicated H-RNTI, or in URA_PCH state, the UE shall start receiving the broadcasted HS-PDSCH code using indicated transport block sizes used for PCCH transmissions in the first HS-DSCH subframe associated with the PICH:

– considering that paging message is transmitted in n subframes;

– combine retransmissions to same HARQ buffer;

– if after decoding the data, the CRC is correct the UE shall pass the data to MAC-ehs;

– if the CRC fails after receiving n subframes the UE resumes the DRX operation.

NOTE: When the UE receives the HS-PDSCH due to reception of PCCH, the UE is not required to receive any HS-SCCH.

The parameter n is broadcasted in system information and the maximum value of n is 5 subframes.

In CELL_PCH state, when the UE is configured with a dedicated H-RNTI, start monitoring the HS-SCCH with the stored dedicated H-RNTI and BCCH specific H-RNTI for 5 subframes after time offset defined between PICH and HS-SCCH:

– if the UE detects the dedicated H-RNTI on the HS-SCCH, the UE shall receive the corresponding HS-DSCH TTI and indicate RRC to initiate sending the measurement results on RACH in uplink:

– if after decoding the data, the CRC is correct the UE passes the data to MAC-ehs for reassembly and reordering;

– after MAC-ehs processing the UE passes the complete MAC-ehs SDU directly to the corresponding RLC entity.

– if the UE does not detect the dedicated H-RNTI in any of the 5 subframes the UE resumes the DRX operation.

– if the UE detects the BCCH specific H-RNTI on the HS-SCCH, the UE shall receive the corresponding HS-DSCH TTI:

– if after decoding the data, the CRC is correct the UE passes the data to MAC-ehs and resumes the DRX operation;

– if the data has not been successfully decoded after 5 subframes the UE resumes the DRX operation;

– if the UE does not detect the BCCH specific H-RNTI in any of the 5 subframes the UE resumes the DRX operation.

The UE shall perform the state transition to CELL_FACH state when sending the measurement results on RACH as defined in 14.2. For uplink transmission the UE shall use the common E-DCH if the UE and cell support it, otherwise it shall use the RACH. After initiating the uplink transmission, the UE shall remain in CELL_ FACH state, unless a state change is triggered by RRC signalling. In case, that state change to CELL_DCH is indicated in RRC message the UE shall initiate uplink synchronisation procedure immediately, if the uplink synchronization procedure is necessary, even if MAC layer has not indicated transmission of the RRC message containing the measurement results on RACH.

During the state transition from CELL_PCH to CELL_DCH, if the reconfiguration message on DCCH does not include new H-RNTI the UE keeps monitoring the HS-SCCH with the dedicated H-RNTI value used in CELL_PCH state during the uplink synchronisation procedure. The UE shall continue to use the dedicated H-RNTI in CELL_DCH state after completing the state transition to CELL_DCH state.