Section: 10.2.6.2 Mapping to resource elements
Content: Narrowband reference signals are transmitted on one or two antenna ports . If the higher layer indicates UE may assume that is equal to , UE may assume - the number of antenna ports for the cell-specific reference signals as defined in clause 6.10.1 is the same as for the narrowband reference signals, - the antenna ports for cell-specific reference signals {0, 1} are equivalent to antenna ports for narrowband reference signals {2000, 2001}, respectively, and - the cell-specific reference signals are available in all subframes where the narrowband reference signals are available. If the higher layer does not indicate UE may assume that is equal to , UE may assume - the number of antenna port for the cell-specific reference signals as defined in clause 6.10.1 is obtained from the higher layer parameter eutra-NumCRS-Ports, - the cell-specific reference signals are available in all subframes where the narrowband reference signals are available, and the cell-specific frequency shift for cell-specific reference signals as defined in clause 6.10.1.2 is given by . The reference signal sequence shall be mapped to complex-valued modulation symbols used as reference symbols for antenna port in slot according to where When frame structure type 2 is used, the following values of apply for the generation of NRSs in special subframes - in each slot for special subframe configurations {3, 4, 8} - in the first slot for special subframe configurations {9, 10} - in the first slot for special subframe configurations {1, 2, 6, 7}. The variables and define the position in the frequency domain for the different reference signals where is given by The cell-specific frequency shift is given by . Resource elements used for transmission of narrowband reference signals on any of the antenna ports in a slot shall not be used for any transmission on any other antenna port in the same slot and set to zero. Narrowband reference signals shall not be transmitted in subframes containing NPSS or NSSS. For frame structure type 2, narrowband reference signals shall not be transmitted in special subframe for configurations 0 and 5. Figure 10.2.6.2-1 illustrates the resource elements used for reference signal transmission according to the above definition. The notation is used to denote a resource element used for reference signal transmission on antenna port. Figure 10.2.6.2-1. Mapping of downlink narrowband reference signals (normal cyclic prefix)