13a MIMO modelling and operation in HSDPA channel in 1.28Mcps TDD

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

In 1.28Mcps TDD, certain categories of UE in CELL_DCH state may be configured to operate in a dual stream MIMO mode.

When the UE is configured in the MIMO mode, the HS-DSCH shall be operated according to the following:

– A MIMO capable UE can be signalled to operate in "MIMO mode" by RRC. When not in MIMO mode it would operate as a regular non-MIMO UE.

– in MIMO mode dynamic scheduling of single and dual stream transmission is possible.

– the Node B signals the number of data streams through HS-SCCH.

– the Node B scheduler determines the number of data stream, single or dual stream, according to the uplink channel estimation and CQI reports from the UE.

– the Node B scheduler determines the orthogonal dual stream precoding vectors, which is obtained by SVD method of reciprocal uplink channel estimation matrix at Node B.

– the Node B shall not schedule UEs with different midamble allocation schemes in the same timeslot.

– for dual stream transmission, the two streams are denoted as stream1 and stream2 respectively.

– two midamble allocation patterns (pattern 1 and pattern 2) for the special default midamble allocation scheme as in [9] shall be used for dual stream transmission. For dual stream transmission, the association between the special midamble allocation pattern and the data stream is predefined, i.e. pattern 1 corresponds to stream1 and pattern 2 corresponds to stream2.

– for dual stream transmission, the relative position of the control signalling field in HS-SCCH and HS-SICH for the two streams is also predefined.

– the total bits of HS-SCCH for single and dual stream are the same.

– for dual stream transmission, the same code allocation shall be used across the two streams.

– the precoding will stay constant during one HS-PDSCH TTI in MIMO mode.

– for single stream transmission, the structure of HS-SICH is kept the same as the legacy HS-SICH.

– for dual stream transmission, the uplink control signalling, i.e. ACK/NACK, RMF and RTBS information of each stream, shall be sent within one HS-SICH TTI, then a new format of HS-SICH with SF=8 shall be used to keep the same code rate as the legacy HS-SICH.

– for the Node B acquiring the entire channel estimation of the two antennas of the UE, UE should time switched transmit the uplink channels by the two antennas, and the transmit antenna may be selected by HCSN or ECSN.