5.9 HS-DSCH procedure in CELL_DCH state

25.2243GPPPhysical layer procedures (TDD)TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5.9.1 Link adaptation procedure

For HS-DSCH, the modulation scheme and effective code rate shall be selected by higher layers located within the Node B. This shall be achieved by appropriate selection of an HS-DSCH transport block size, modulation format and resources by higher layers. If the UE is configured in MIMO mode, higher layers may select the number of data streams, i.e. single or dual stream HS-DSCH transmission, and the transport block size, modulation format and resources for each stream. The Node B shall decide the number of data streams based on the uplink channel estimation and CQI reports from the UE. If UE supports multi-carrier HS-DSCH reception, higher layers may select multiple carriers to transfer data. Carriers selection may be based on CQI reports from the UE. If UE supports multi-carrier HS-DSCH transmission, UE shall report the CQI information of every carrier via HS-SICH.

The overall HS-DSCH link adaptation procedure consists of two parts:

Node B procedure:

1) The NodeB transmits HS-SCCH carrying a UE identity identifying the UE to which HS-DSCH TTI is to be granted. In case of HS-DSCH transmissions in consecutive TTIs to the same UE, the same HS-SCCH shall be used for associated signalling. If the UE is configured in MIMO mode, the Node B shall determine appropriate HS-SCCH type for single or dual stream HS-DSCH transmission. If UE supports multi-carrier HS-DSCH reception, above HS-SCCH detection procedure applied on each independent carriers.

2) The NodeB transmits HS-DSCH to the UE using the grant indicated in the HS-SCCH. If UE supports multi-carrier HS-DSCH reception, the mapping relation between HS-SCCH and its associated HS-DSCH is set by higher layers.

3) Upon receiving the HS-SICH from the respective UE, the status report (ACK/NACK and CQI) shall be passed to higher layers. If UE supports multi-carrier HS-DSCH reception, the mapping relation between HS-SICH and its associated HS-DSCH is set by higher layers.

UE procedure:

1) When indicated by higher layers, the UE shall start monitoring all HS-SCCHs that are in its HS-SCCH set as signalled to it by higher layers. The information carried on the HS-SCCH is described in [8]. If UE supports multi-carrier HS-DSCH reception, the monitoring HS-SCCH set is signalled by higher layers.

2) In the case that a HS-SCCH is identified to be correct by its CRC, the UE shall read the HS-PDSCHs indicated by the HS-SCCH. If the UE is configured in MIMO mode, UE may acquire HS-PDSCH resource allocation information of each stream according to the associated HS-SCCH. If UE supports multi-carrier HS-DSCH reception, UE may acquire HS-PDSCH resource allocation information of each carrier according to the associated HS-SCCHs, the mapping relation between every HS-SCCH and its associated HS-PDSCH is signalled by higher layers. In the case that a HS-SCCH is identified to be incorrect, the UE shall discard the data on the HS-SCCH and return to monitoring.

3) After reading the HS-PDSCHs, the UE shall generate an ACK/NACK message and transmit this to the NodeB in the associated HS-SICH, along with the most recently derived CQI. If the UE is configured in MIMO mode, the CQI and ACK/NACK of each stream are transferred via the associated HS-SICH. If UE supports multi-carrier HS-DSCH reception, the CQI and ACK/NACK of every carrier are transferred via individual HS-SICH.

The mapping of HS-PDSCH channelisation code set and timeslot information carried by the HS-SCCH for a given HS-DSCH TTI is described in [9].

For a given allocation of HS-PDSCH resources to a UE for a specific HS-DSCH TTI, the following shall apply:

– If timeslot information on HS-SCCH indicates two or more timeslots, none of these timeslots shall comprise a beacon channel.

– If timeslot information on HS-SCCH indicates a single timeslot and this timeslot comprises a beacon channel then:

– The Node-B shall not indicate SF=1 for any HS-PDSCH resource.

– The set of HS-PDSCH resources allocated by the Node-B to a UE shall exclusively comprise either beacon function or non-beacon function physical channels. The Node B shall therefore not allocate both beacon function and non-beacon function physical channels within the beacon timeslot to the UE. If the HS-DSCH for a specific HS-DSCH TTI is mapped to the beacon channel, this shall be signalled using k_start = 1 and k_stop = 1. For a definition of the first and last allocated channelisation code indices k_start and k_stop on HS-SCCH refer to [9].

– When SCTD antenna diversity is applied to the beacon channel, then the presence of channelisation code within the channelisation code set information on HS-SCCH shall implicitly indicate the presence of channelisation code .

5.9.2 HS-DSCH channel quality indication procedure

For the HS-SICH associated to the HS-SCCH command for allocation or release of the semi-persistent HS-PDSCH resources and HS-SCCH command for activation or deactivation of DRX and the HS-SICH associated to HS-SCCH type1 or HS-SCCH type 4 or HS-SCCH type 8 with transport block size information set to all zeros, UE shall feedback ACK and CQI on HS-SICH with RTBS equals to zero.

The channel quality indicator (CQI) provides the Node B with an estimate of the code rate that would have maximized the single-transmission throughput of the previous HS-DSCH transmission if decoded in isolation. The CQI report requires to be referenced to a given set of HS-PDSCH resources by the Node B, but note that the UE is not restricted to making measurements only on these reference resources when deriving a given CQI. The reference resources for a CQI report shall be a set of HS-PDSCH resources that were received by the UE in a single TTI, and contain a complete transport block. These resources will be known to the Node B from the relative timings of the HS-SICH carrying the CQI and previous HS-DSCH transmissions to the UE.

The CQI consists of two fields; a Recommended Transport Block Size (RTBS) and a Recommended Modulation Format (RMF). The UE shall use the same mapping table for these fields as is being used for the time slot information and modulation scheme information fields respectively of the HS-SCCH [18]. If the UE is configured in MIMO mode, the HS-SICH shall consists of the CQI reports of each stream, i.e. the RTBS and RMF of each stream.

The reporting procedure is as follows:

1. The UE receives a message on an HS-SCCH telling it which resources have been allocated to it for the next associated HS-DSCH transmission.

2. The UE reads the associated HS-DSCH transmission, and makes the necessary measurements to derive a CQI that it estimates would have given it the highest single-transmission throughput for the allocated resources whilst achieving a BLER of no more than 10 %. If the UE is configured in MIMO mode, the CQI would have given the highest single-transmission throughput for each stream respectively in the allocated resources whilst achieving BLER of each stream of no more than 10%.

BLER, in this context, is defined as the probability that a transport block transmitted using the RTBS and RMF is received in error if decoded in isolation. For the purposes of this calculation, it shall be assumed that the transport block that would be transmitted with these parameters would use redundancy version parameters s = 1 and r = 0. Note that, by this definition, a UE shall never report a CQI that corresponds to a code rate greater than unity.

Using this definition of BLER, single-transmission throughput shall be defined as follows :

single-transmission throughput = (1 – BLER)  RTBS

If the UE is configured in MIMO mode, the single-transmission throughput shall be defined as the sum of each stream throughput.

3. The CQI report derived from a given HS-DSCH transmission shall be reported to the Node B in the next HS-SICH available to the UE following that HS-DSCH transmission, unless that HS-SICH immediately follows the last allocated HS-DSCH timeslot, in which case the subsequent available HS-SICH shall be used by the UE. This HS-SICH may not necessarily be the same HS-SICH that carries the ACK/NACK information for that HS-DSCH transmission. The UE shall always transmit the most recently derived CQI in any given HS-SICH, which may mean that some CQI reports are discarded without being transmitted to the Node B.

5.9.3 HS-SCCH monitoring procedure

If HS_SCCH_DRX_Active is FALSE, UE shall monitor a set of HS-SCCHs as follows.

For 1.28Mcps TDD, in a multi-frequency HS-DSCH cell, a UE divides its HS-SCCH set into one or more HS-SCCH subsets; in each HS-SCCH subset all HS-SCCHs are associated with the same frequency’s HS-PDSCH. When indicated by higher layers, the UE shall start monitoring all HS-SCCHs in all HS-SCCH subsets to acquire the configuration information of HS-PDSCHs. In the case that one HS-SCCH is detected carrying its UE identity, the UE shall skip monitoring the remaining HS-SCCHs in this HS-SCCH subset, and restrict its monitoring only to previously detected HS-SCCH in the following TTIs. The UE shall set all HS-SCCHs carrying its UE identity in all HS-SCCH subsets into an active set, and set all HS-SCCH subsets in which no HS-SCCH carries its UE identity into a remaining set.

In the case that the multi-carrier number (as described in [15]) is not configured by high layers, a UE shall always monitor all HS-SCCH subsets. Otherwise, the UE may skip monitoring remaining HS-SCCH subsets when the number of HS-SCCHs carrying its UE identity, i.e. the number of HS-SCCHs in the active set, is equal to the configured value.

During the following TTIs, the UE shall update and maintain the active set and the remaining set. If one or more HS-SCCHs in the active set do not carry its UE identity, the UE shall remove them from the active set and set their corresponding HS-SCCH subsets into remaining set. Meanwhile, if one or more HS-SCCHs in remaining sets are detected carrying its UE identity, the UE shall set these founded HS-SCCHs into the active set and remove their corresponding HS-SCCH subsets from the remaining set.

If HS_SCCH_DRX_Active is TRUE, UE shall monitor a set of HS-SCCHs in the subframes according to rules defined in the subclause 5.13.