18 Dual Cell HSDPA Operation (FDD only)

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

Dual Cell operation is characterized as simultaneous reception of up to two HS-DSCH transport channels. Certain categories of UEs may be configured with Dual Cell operation with or without MIMO in CELL_DCH state. Dual Cell operation may be activated and deactivated using HS-SCCH orders.

When the UE is configured with Dual Cell operation, a common transmitting MAC-ehs entity is used for data transmission, and the HS-DSCH channels shall be operated in the following manner,

– the receiving MAC-ehs entity supports up to two HS-DSCH transport channels.

– each of these HS-DSCH transport channels has its own associated uplink and downlink signalling, and own HARQ entity (further composed of multiple HARQ processes).

– reordering, duplicate detection, segmentation and reassembly functions are joint for these HS-DSCH transport channels and HARQ entities.

When the UE is configured with Dual Cell HSDPA operation:

– the mobility procedures, as defined in section 9, are supported based on the serving HS-DSCH cell. Figure 18-1 shows an example of combined active set update and HS-Serving Cell Change based on received measurement report 1A. The procedure may also be performed in two steps with separate Active Set Update and Radio Bearer Reconfiguration messages.

– the DRX status and activation and deactivation of the DRX with HS-SCCH is common to both serving and secondary serving HS-DSCH cells, and the related HS-SCCH signaling can be sent on either serving or secondary serving HS-DSCH cell,

– HS-SCCH-less operation is restricted to the serving HS-DSCH cell.

– there is only one CCTrCH of HS-DSCH type per cell.

– the maximum number of HS-SCCHs as seen from the UE’s point of view is 6 with a maximum of 4 HS-SCCHs per cell.

– DC-HSDPA operation configured on two frequency bands is called Dual Band Operation and is described in subsection 18.2.

– for dual cell HSDPA operation or Dual Band Operation, DC-HSDPA operation when MIMO is configured is described in 18.1.

– for dual cell HSDPA operation or Dual Band Operation, DC-HSDPA operation when MIMO mode with four transmit antennas is configured is described in 13c.

– for dual cell HSDPA operation on single frequency band, the UE may be configured with Dual Cell E-DCH operation as is described in [3].

Figure 18-1: Intra-Node B synchronised serving HS-DSCH cell change for Dual Cell operation

18.1 Dual Cell HSDPA and MIMO

In FDD, certain categories of UE in CELL_DCH state may be configured to operate in Dual Cell HSDPA and MIMO mode per cell. MIMO operation per cell is performed as per section 13.

When the UE is configured with Dual Cell HSDPA and MIMO, the HS-DSCH shall be operated in the following manner:

– A single channelization code HS-DPCCH is used to carry feedback information (ACK/NACK, CQI and precoding control information) related to the two HS-DSCH transport channels.

– CQI reports related to the two HS-DSCH transport channels are transmitted in a TDM manner.

– The CQI report corresponding to the HS-DSCH on the serving HS-DSCH cell, is referred to as CQI1, and the CQI report corresponding to the HS-DSCH on the secondary serving HS-DSCH cell, is referred to as CQI2. In case of repetition, CQI1 repetitions are transmitted first, followed by all CQI2 repetitions. In case of UL DTX operation, all repetitions of both CQI1 and CQI2 are transmitted whenever CQI is supposed to be transmitted according to Rel-7 UL DTX specification.

– When the serving HS-DSCH cell deactivates Dual Cell HSDPA operation, the UE reverts to Rel-7 MIMO format for HS-DPCCH (similarly as for Rel-8 Dual Cell HSDPA operation without MIMO), and CQI2 is not transmitted.

– The TSN field in the MAC-ehs header is extended to 14 contiguous bits.

– The maximum number of MAC-ehs PDUs per TTI is 4. Either one of the serving HS-DSCH cell and the secondary serving HS-DSCH cell, or both of the cells, can be configured with MIMO operation.

– The maximum number of MAC-ehs PDUs per TTI is 8. Either one of the serving HS-DSCH cell and the secondary serving HS-DSCH cell, or both of the cells, can be configured with MIMO mode with four transmit antennas operation.

18.2 Dual Band HSDPA Operation

Dual Band operation is characterized as simultaneous reception of up to two HS-DSCH transport channel which are carried over two radio frequency bands. Certain categories of UEs may be configured with Dual Band operation in CELL_DCH state. Dual Band operation may be activated and deactivated using HS-SCCH orders.