22 Multiflow Operation (FDD only)
25.3083GPPHigh Speed Downlink Packet Access (HSDPA)Overall descriptionRelease 17Stage 2TS
Multiflow operation is characterized as simultaneous reception of up to four HS-DSCH transport channels in the CELL_DCH state, where up to two HS-DSCH transport channels may reside at the same frequency and belong either to same or different Node Bs. Table 22-1 lists configurations supported by this version of the standard.
Table 22-1: Multiflow configurations
|
Name |
Carrier Frequency A |
Carrier Frequency B |
Carrier Frequency C |
|
One Frequency, two cells |
The serving HS-DSCH cell, |
N/A |
N/A |
|
Two frequencies, three cells |
The serving HS-DSCH cell, |
A secondary serving HS-DSCH cell |
N/A |
|
Two frequencies, three cells |
The serving HS-DSCH cell, |
An assisting secondary serving HS-DSCH cell |
N/A |
|
Two frequencies, four cells |
The serving HS-DSCH cell, |
A secondary serving HS-DSCH cell, |
N/A |
|
Three frequencies, four cells |
The serving HS-DSCH cell, |
A secondary serving HS-DSCH cell |
A secondary serving HS-DSCH cell |
|
Three frequencies, four cells |
The serving HS-DSCH cell, |
An assisting secondary serving HS-DSCH cell |
An assisting secondary serving HS-DSCH cell |
Depending on its capabilities, a UE may be configured to operate in multiple radio frequencies as follows:
– Certain UE type may be configured with up to four HS-DSCH transport channels operating on two carrier frequencies or on three carrier frequencies adjacent to each other.
– Certain UE type may be configured with up to four HS-DSCH transport channels operating on two carrier frequencies or on three carrier frequencies on two different frequency bands.
– Certain UE type may be configured with up to four HS-DSCH transport channels on two carrier frequencies or on three carrier frequencies on the same frequency band, but not adjacent to each other.
– Certain UE types may be configured with three or four HS-DSCH transport channel operating on two adjacent carrier frequencies or on three adjacent carrier frequencies and with Dual Cell E-DCH operation, as described in [3].
When the UE is configured with Multiflow operation:
– There is one serving HS-DSCH cell. There can be an assisting serving HS-DSCH cell and additional secondary serving and assisting secondary serving HS-DSCH cells as defined in Table 22-1.
– The serving and secondary serving HS-DSCH cells have the same downlink timing, and the same applies to the assisting serving and assisting secondary serving HS-DSCH cells. Configured HS-DSCH cells may have at most two different downlink timings.
– The mobility procedures, as defined in section 9, are supported based on the serving HS-DSCH cell. A serving cell change similar to the one shown in Figure 18-1 is possible for Multiflow operation.
– When configured with MIMO on at least one of the HS-DSCH cells and/or there are more than two HS-DSCH cells, the TSN field in the MAC-ehs header is extended to 14 contiguous bits.
– The secondary serving and assisting secondary serving HS-DSCH cells can be activated and deactivated using HS-SCCH orders, which can be sent only from one of the cells belonging to the same Node B.
– The DTX/DRX status is common for all the HS-DSCH cells.
– HS-SCCH-less operation is restricted to the serving HS-DSCH cell.
– UEs of certain capabilities may be configured to operate in MIMO mode as follows:
– Depending on the UE capabilities, either single or dual stream MIMO transmission can be configured per serving HS-DSCH cell.
– MIMO operation per serving HS-DSCH cell is performed as per section 13.
– The maximum number of MAC-ehs PDUs per TTI is 1 for each activated serving HS-DSCH cell for an HS-DSCH cell configured in the non-MIMO mode, and at most 2 for each activated serving HS-DSCH cell configured in MIMO mode.
– Synchronization and Radio Link Failure:
– When Multiflow is configured to operate on a single carrier frequency, the synchronization and RLF operates as defined for single carrier HSDPA.
– When Multiflow is configured to operate on two carrier frequencies, the synchronization and RLF operate as defined for Dual-Cell HSDPA.
– When Multiflow is configured to operate on three carrier frequencies, the synchronization and RLF operate as defined for 3C-HSDPA.
– Measurements:
– If only one uplink frequency is configured, the UE performs intra-frequency measurement only on the primary downlink frequency.
– If two uplink frequencies are configured, the UE performs intra-frequency measurement on the corresponding primary downlink frequency and secondary downlink frequency.
– Combination with UL MIMO or UL CLTD:
– It is possible to configure Multiflow operation together with UL MIMO or UL CLTD.
In case of inter-Node B Multiflow operation combined with UL MIMO or UL CLTD, HS-SCCH orders related to UL MIMO or UL CLTD are limited only to the cells belonging to the serving Node B.
– It is possible to configure Multiflow operation together with UL CLTD with the F-TPICH feedback transmitted from the assisting serving HS-DSCH cell. In case of inter-Node B Multiflow operation with the F-TPICH feedback from the assisting serving HS-DSCH cell, HS-SCCH orders related to UL CLTD are limited only to the cells belonging to the assisting Node B.
When the UE is configured with intra-Node B Multiflow operation, the HS-DSCH channels shall be operated in the following manner:
– The downlink data is split at the MAC-ehs level.
– A common transmitting MAC-ehs entity is used for data transmission.
– The transmitting and receiving MAC-ehs entity support up to four HS-DSCH transport channels.
– Reordering, duplicate detection, segmentation and reassembly functions are common for these HS-DSCH transport channels and HARQ entities.
– Each of HS-DSCH transport channels has its own associated uplink and downlink signalling, and own HARQ entity (further composed of multiple HARQ processes).
Figure 22-1: Protocol Architecture of intra-Node B Multiflow (configuration without MAC-c/sh)
When the UE is configured with inter-Node B Multiflow operation, the HS-DSCH channels shall be operated in the following manner:
– The downlink data is split at the RLC level. If configured by the network, a UE uses the RLC level re-ordering timer.
– Two transmitting MAC-ehs entities are used for data transmission.
– Each transmitting and receiving MAC-ehs entity support up to two HS-DSCH transport channels.
– Each MAC-ehs entity performs independently reordering, duplicate detection, segmentation and reassembly functions for the correspondent HS-DSCH transport channels and HARQ entities.
– 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).
Figure 22-2: Protocol Architecture of inter-Node B Multiflow (configuration without MAC-c/sh)