13 MIMO modelling and operation in HSDPA channel in FDD

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

In FDD, certain categories of UE in CELL_DCH state may be configured to operate in a MIMO mode.

In FDD, certain UEs in CELL_DCH state may be configured to operate in a MIMO mode and restriction to single stream transmission only. The UE’s capability of supporting the MIMO mode when single-stream restriction is configured is independent from the UE’s support for MIMO mode when single-stream restriction is not configured.

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

– Use of MIMO in a cell does not enforce use of transmit diversity on overhead channels

– 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 when single-stream restriction is not configured dynamic scheduling of single and dual stream transmission is possible.

– in MIMO mode when single-stream restriction is configured only single stream transmission is possible.

– when operating in MIMO mode, the use of F-DPCH as associated channel shall be supported

– when operating in MIMO mode and using F-DPCH as associated channel, only single antenna transmission or STTD has to be supported on F-DPCH.

– when operating in MIMO mode, the use of DPCH as associated channel shall be supported.

– additionally the data rate on DPCH should be limited (e.g. to 64 kbps) when operating in MIMO mode.

– the Rel-6 transport block sizes shall be reused without changes

– the Node B signals the number of scheduled streams (not applicable when single-stream restriction is configured) and the used antenna weights through HS-SCCH.

– a precoding codebook with 4 vectors has been defined

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

– for dual stream transmissions, orthogonal precoding vectors are used

– the Node B scheduler decides on which precoding vector(s) is/are used

– the UE signals 1 out of 4 possible precoding vectors in the uplink

– the UE sends sufficient information to the Node B to select the number of streams (not applicable when single-stream restriction is configured) and the MCSs of each stream

– for the purpose of CQI evaluation, the UE assumes to get symmetric code allocation across streams (not applicable when single-stream restriction is configured).

– the UE will ACK/NACK each transmitted transport block separately.