6.10.4 Positioning reference signals
36.2113GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical channels and modulationRelease 17TS
Positioning reference signals shall only be transmitted in resource blocks in downlink subframes configured for positioning reference signal transmission. If both normal and MBSFN subframes are configured as positioning subframes within a cell, the OFDM symbols in a MBSFN subframe configured for positioning reference signal transmission shall use the same cyclic prefix as used for subframe #0. If only MBSFN subframes are configured as positioning subframes within a cell, the OFDM symbols configured for positioning reference signals in the MBSFN region of these subframes shall use extended cyclic prefix length. In a subframe configured for positioning reference signal transmission, the starting positions of the OFDM symbols configured for positioning reference signal transmission shall be identical to those in a subframe in which all OFDM symbols have the same cyclic prefix length as the OFDM symbols configured for positioning reference signal transmission.
Positioning reference signals are transmitted on antenna port 6.
The positioning reference signals shall not be mapped to resource elements 
allocated to the core part of the PBCH, PSS or SSS regardless of their antenna port 
.
Positioning reference signals are defined for 
only.
6.10.4.1 Sequence generation
The reference-signal sequence 
is defined by
where 
is the slot number within a radio frame, 
is the OFDM symbol number within the slot. The pseudo-random sequence 
is defined in clause 7.2. The pseudo-random sequence generator shall be initialised with 
at the start of each OFDM symbol where 
equals 
unless configured by higher layers and where
6.10.4.2 Mapping to resource elements
If PRS frequency hopping is not configured by higher layers, the reference signal sequence 
shall be mapped to complex-valued modulation symbols 
used as reference signal for antenna port 
in slot 
according to
where
Normal cyclic prefix:
Extended cyclic prefix:
The bandwidth for positioning reference signals 
is configured by higher layers and the cell-specific frequency shift is given by 
where 
if no value for 
is configured by higher layers.
If PRS frequency hopping is configured by higher layers, a PRS frequency hopping configuration provided by higher layers contains the following:
– The length of the PRS occasion group, 
– Number of PRS frequency hopping bands, 
– 
defined as twice the starting PRB index of PRS frequency hopping band 
where
– 
if 
,
– 
where 
is the index of the first PRB in the PRS frequency hopping narrowband configured by higher layers if 
If PRS frequency hopping is configured by higher layers, the reference signal sequence 
in the PRS occasion 
, 
, in the PRS occasion group shall be mapped to complex-valued modulation symbols 
used as reference signal for antenna port 
in slot 
according to
where
– for normal cyclic prefix
– for extended cyclic prefix
Figure 6.10.4.2-1: Mapping of positioning reference signals (normal cyclic prefix)
Figure 6.10.4.2-2: Mapping of positioning reference signals (extended cyclic prefix)
6.10.4.3 Positioning reference signal subframe configuration
The subframe configuration period 
and the subframe offset 
for the transmission of positioning reference signals are listed in Table 6.10.4.3-1. The PRS configuration index 
is configured by higher layers. Positioning reference signals are transmitted only in configured DL subframes. Positioning reference signals shall not be transmitted in DwPTS. Positioning reference signals shall be transmitted in 
consecutive downlink subframes, where 
is configured by higher layers.
The positioning reference signal instances, for the first subframe of the 
downlink subframes, shall satisfy 
.
Table 6.10.4.3-1: Positioning reference signal subframe configuration
|
PRS configuration Index |
PRS periodicity (subframes) |
PRS subframe offset (subframes) |
|
0 – 159 |
160 |
|
|
160 – 479 |
320 |
|
|
480 – 1119 |
640 |
|
|
1120 – 2399 |
1280 |
|
|
2400 – 2404 |
5 |
|
|
2405 – 2414 |
10 |
|
|
2415 – 2434 |
20 |
|
|
2435 – 2474 |
40 |
|
|
2475 – 2554 |
80 |
|
|
2555-4095 |
Reserved |
|
