Section: 6.10.5.2 Mapping to resource elements
Content: In subframes configured for CSI reference signal transmission, the reference signal sequence shall be mapped to complex-valued modulation symbols used as reference symbols on antenna port . The mapping depends on the higher-layer parameter CDMType. For the case of CDMType is not configured or is configured to CDM2: where For the case of CDMType equal to CDM4: where and where is given by Table 6.10.5.2-0. Table 6.10.5.2-0: The sequence for CDM4. If neither of the higher-layer parameters NZP-FrequencyDensity and NZP-TransmissionComb are configured, . If the UE is configured with one or more of the parameters NZP-FrequencyDensity and NZP-TransmissionComb, - if either NZP-FrequencyDensity equals 1, - if NZP-FrequencyDensity equals 1/2 and NZP-TransmissionComb equals 0, - if NZP-FrequencyDensity equals 1/2 and NZP-TransmissionComb equals 1, - if NZP-FrequencyDensity equals 1/3 and NZP-TransmissionComb equals 0, - if NZP-FrequencyDensity equals 1/3 and NZP-TransmissionComb equals 1, - if NZP-FrequencyDensity equals 1/3 and NZP-TransmissionComb equals 2, The quantity and the necessary conditions on are given by Tables 6.10.5.2-1 and 6.10.5.2-2 for normal and extended cyclic prefix, respectively. The relation between the antenna port number and the quantity depends on the number of CSI-RS antenna ports: - for CSI reference signals using up to eight antenna ports, - for CSI reference signals using more than eight antenna ports when the higher-layer parameter CDMType equals CDM2 where is the CSI-RS resource number. - for CSI reference signals using more than eight antenna ports when the higher-layer parameter CDMType equals CDM4, antenna port number where for CSI-RS resource number . For the case of CDMType equal to CDM8 and the number of CSI-RS antenna ports equal to 32: where The resource elements for the CDM8 pattern, where , are determined by aggregating pairs of resource elements satisfying from the aggregated CSI-RS configurations, where at most one pair of resource elements is drawn from each of the aggregated CSI-RS configurations. For the case of CDMType equal to CDM8 and the number of CSI-RS antenna ports equal to 32, the aggregated CSI-RS configurations from Table 6.10.5.2-1 for normal cyclic prefix and from Table 6.10.5.2-2 for extended cyclic prefix are restricted to one of , , or . Antenna port number where for CSI-RS resource number . The sequence is given by Table 6.10.5.2-0A, where . Table 6.10.5.2-0A: The sequence for CDM8 with 32 CSI-RS antenna ports. For the case of CDMType equal to CDM8 and the number of CSI-RS antenna ports equal to 24: where For the case of CDMType equal to CDM8 and the number of CSI-RS antenna ports equal to 24, the aggregated CSI-RS configurations from Table 6.10.5.2-1 for normal cyclic prefix are restricted to in that order. Resource elements for CDM8 patterns are determined as follows: - Aggregating resource element quadruplet satisfying from CSI-RS configuration 1 with resource element quadruplet satisfying from CSI-RS configuration 2 - Aggregating resource element quadruplet satisfying from CSI-RS configuration 3 with resource element quadruplet satisfying from CSI-RS configuration 1 - Aggregating resource element quadruplet satisfying from CSI-RS configuration 2 with resource element quadruplet satisfying from CSI-RS configuration 3 Antenna port number where for CSI-RS resource number . The sequence is given by Table 6.10.5.2-0B. The sequence index is determined as follows: - For resource element quadruplet satisfying from CSI-RS configuration 1, resource element quadruplet satisfying from CSI-RS configuration 2, or resource element quadruplet satisfying from CSI-RS configuration 3, . - For resource element quadruplet satisfying from CSI-RS configuration 1, resource element quadruplet satisfying from CSI-RS configuration 2, or resource element quadruplet satisfying from CSI-RS configuration 3, . Table 6.10.5.2-0B: The sequence for CDM8 with 24 CSI-RS antenna ports. Multiple CSI reference signal configurations can be used in a given cell. A UE can be configured with multiple sets of CSI reference signals, - one or more configurations for CSI reporting for which the UE shall assume non-zero transmission power for the CSI-RS, and - zero or more configurations for which the UE shall assume zero transmission power, and - zero or more configurations valid across the system downlink bandwidth as part of the discovery signals for which the UE shall assume non-zero transmission power for the CSI-RS. The CSI-RS configurations for which the UE shall assume non-zero transmission power are provided by higher layers. The CSI-RS configurations for which the UE shall assume zero transmission power in a subframe are given by a bitmap derived according to clause 7.2.7 in TS 36.213[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures ]  [4]. For each bit set to one in the 16-bit bitmap, the UE shall assume zero transmission power for the resource elements corresponding to the four CSI reference signal column in Tables 6.10.5.2-1 and 6.10.5.2-2 for normal and extended cyclic prefix, respectively, except for resource elements that overlap with those for which the UE shall assume non-zero transmission power CSI-RS as configured by higher layers. The most significant bit corresponds to the lowest CSI reference signal configuration index and subsequent bits in the bitmap correspond to configurations with indices in increasing order. CSI reference signals not corresponding to higher layer configured parameters csi-RS-ConfigNZP-ApList or csi-RS-ConfigZP-ApList can only occur in - downlink slots where fulfils the condition in Tables 6.10.5.2-1 and 6.10.5.2-2 for normal and extended cyclic prefix, respectively, and - where the subframe number fulfils the conditions in clause 6.10.5.3. CSI reference signals corresponding to either higher layer configured parameter csi-RS-ConfigNZP-ApList or csi-RS-ConfigZP-ApList can only occur in - downlink slots where fulfils the condition in Tables 6.10.5.2-1 and 6.10.5.2-2 for normal and extended cyclic prefix, respectively. The UE shall assume that CSI reference signals are not transmitted - in the DwPTS for special subframe configuration 0, 5, 9 and 10 for normal cyclic prefix and special subframe configuration 0, 4 and 7 for extended cyclic prefix, in case of frame structure type 2, - in the DwPTS for normal CP for the case of CDMType equal to CDM8 and the number of CSI-RS antenna ports equal to 24, - in subframes where PDSCH/EPDCCH transmission starts in the second slot of a subframe for frame structure type 3, - in subframes where PDSCH/EPDCCH transmission ends prior to the end of a subframe for frame structure type 3, - in an empty subframe where there is no PDSCH or discovery signal transmission for frame structure type 3, - in subframes where transmission of a CSI-RS would collide with SystemInformationBlockType1 messages, - in the primary cell in subframes configured for transmission of paging messages in the primary cell for any UE with the cell-specific paging configuration. For special subframe configuration {1, 2, 6, or 7}, a UE does not expect to be configured with one of CSI-RS configurations {1, 2, 3, 4, 6, 7, 8, 9, 12, 13, 14, 15, 16, 17} in DwPTS for normal CP. The UE shall assume that none of the CSI reference signals corresponding to a CSI reference signal configuration are transmitted in subframes where transmission of any of those CSI reference signals would collide with transmission of synchronization signals or the core part of PBCH. Resource elements used for transmission of CSI reference signals on any of the antenna ports in the set , where , , , , , , , , , , , , , , , or shall not be used for transmission of PDSCH on any antenna port in the same slot if higher layer parameter CDMType is not configured, or is configured to CDM2. Resource elements used for transmission of CSI reference signals on any of the antenna ports in the set , where - , or for CSI reference signals on 12 ports, or - , , or for CSI reference signals on 16 ports, or - , , , or for CSI reference signals on 20 ports, or - , , , , or for CSI reference signals on 24 ports, or - , , , ,, or for CSI reference signals on 28 ports, or - , , , , , , or for CSI reference signals on 32 ports shall not be used for transmission of PDSCH on any antenna port in the same slot if higher layer parameter CDMType is configured to CDM4. Resource elements used for transmission of CSI reference signals on any of the antenna ports in the set , where - , or for CSI reference signals on 24 ports, or - , , or for CSI reference signals on 32 ports shall not be used for transmission of PDSCH on any antenna port in the same slot if higher layer parameter CDMType is configured to CDM8. The mapping for CSI reference signal configuration 0 is illustrated in Figures 6.10.5.2-1 and 6.10.5.2-2. Table 6.10.5.2-1: Mapping from CSI reference signal configuration to for normal cyclic prefix Note: . Configurations 0 – 19 for normal subframes are available for frame structure types 1, 2 and 3. Configurations 20 – 31 and configurations for special subframes are available for frame structure type 2 only. Table 6.10.5.2-2: Mapping from CSI reference signal configuration to for extended cyclic prefix. Note: . Configurations 0 – 15 for normal subframes are available for both frame structure type 1 and type 2. Configurations 16 – 27 and configurations for special subframes are available for frame structure type 2 only. Figure 6.10.5.2-1: Mapping of CSI reference signals (CSI configuration 0, normal cyclic prefix) Figure 6.10.5.2-2: Mapping of CSI reference signals (CSI configuration 0, extended cyclic prefix)