Section: 6.2.1 Resource grid
Content: The transmitted signal in each slot is described by one or several resource grids of subcarriers and OFDM symbols. The resource grid structure is illustrated in Figure 6.2.2-1. The quantity depends on the downlink transmission bandwidth configured in the cell and shall fulfil where and are the smallest and largest downlink bandwidths, respectively, supported by the current version of this specification. The set of allowed values for is given by TS 36.104[ Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) radio transmission and reception ]  [6]. The number of OFDM symbols in a slot depends on the cyclic prefix length and subcarrier spacing configured and is given in Table 6.2.3-1. An antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed. For MBSFN reference signals, positioning reference signals, UE-specific reference signals associated with PDSCH, demodulation reference signals associated with SPDCCH, and demodulation reference signals associated with EPDCCH, there are limits given below within which the channel can be inferred from one symbol to another symbol on the same antenna port. There is one resource grid per antenna port. The set of antenna ports supported depends on the reference signal configuration in the cell: - Cell-specific reference signals support a configuration of one, two, or four antenna ports and are transmitted on antenna ports ,, and , respectively. - MBSFN reference signals are transmitted on antenna port. The channel over which a symbol on antenna portis conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed only if the two symbols correspond to subframes (slots in case of 0.37 kHz subcarrier spacing) of the same MBSFN area. - UE-specific reference signals associated with PDSCH intended for non-BL/CE UE are transmitted on antenna port(s) , , , or one or several of . The channel over which a symbol on one of these antenna ports is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed only if the two symbols are within the same subframe and in the same PRG when PRB bundling is used or in the same PRB pair when PRB bundling is not used. - UE-specific reference signals associated with PDSCH intended for BL/CE UE are transmitted on one or several of antenna port(s) . The channel over which a symbol on one of these antenna ports is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed only if the two symbols are in the same set of consecutive subframes and have the same PRB index. - Demodulation reference signals associated with EPDCCH are transmitted on one or several of . The channel over which a symbol on one of these antenna ports is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed only if the two symbols are in the same PRB pair. - Demodulation reference signals associated with MPDCCH are transmitted on one or several of . The channel over which a symbol on one of these antenna ports is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed only if the two symbols are in the same set of consecutive subframes and have the same PRB index. - Demodulation reference signals associated with SPDCCH are transmitted on . - Positioning reference signals are transmitted on antenna port. The channel over which a symbol on antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed only within one positioning reference signal occasion consisting of consecutive downlink subframes, where is configured by higher layers. - CSI reference signals support a configuration of 1, 2, 4, 8, 12, 16, 20, 24, 28, or 32 antenna ports and are transmitted on antenna ports , , , , , , , , and, respectively. Two antenna ports are said to be quasi co-located if the large-scale properties of the channel over which a symbol on one antenna port is conveyed can be inferred from the channel over which a symbol on the other antenna port is conveyed. The large-scale properties include one or more of delay spread, Doppler spread, Doppler shift, average gain, and average delay.