Enhanced node B, UE and method for selecting cell discovery signals in LTE networks
Embodiments allow selection of a Discovery signal (DS) used to identify an eNB to a UE receiving the DS. The DS allows the UE to ascertain the existence and/or cell identifier of the eNB. DS comprise a plurality of other signals such as a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a Cell Specific Reference Signal (CRS) and/or a Channel State Information Reference Signal (CSI-RS). A DS occasion comprises a number of subframes where the selected signals that comprise the DS are transmitted. The signals selected for the DS, their characteristics and properties allow a UE to decode the cell identifier. The DS occasion occurs with a designated periodicity.
1. A method comprising:
decoding a message that includes a value indicating a periodicity of one of 40 milliseconds, 80 milliseconds, and 160 milliseconds for discovery signal (DS) occasions;
decoding a DS received within the DS occasion, the DS comprising:
a cell-specific reference signal (CRS);
a primary synchronization signal (PSS); and
only one secondary synchronization signal (SSS), wherein for frame structure type 1, the PSS is received in a first subframe of the DS occasion and for frame structure type 2, the PSS is received in a second subframe of the DS occasion.
2. The method of claim 1 , further comprising connecting to a small cell based on the DS.
3. The method of claim 1 , wherein the DS occasion comprises a period having a duration of:
one to five consecutive subframes for frame structure type 1, and
two to five consecutive subframes for frame structure type 2.
4. The method of claim 3 , wherein the DS comprises the CRS on antenna port 0 in a downlink subframe and in a subframe containing a Downlink Pilot Time Slot (DwPTS) of the DS occasion; and
wherein the DS further comprises a non-zero-power Channel State Information Reference Signal (CSI-RS) transmitted in zero or more subframes in the period.
5. The method of claim 1 , wherein the PSS and the SSS are received within a same subframe of a sequence of subframes and wherein the PSS is received before the SSS within the subframe.
6. The method of claim 1 , wherein a location of time domain and/or frequency domain for PSS, SSS and/or CRS is based upon either a cell identifier or virtual cell identifier.
7. A method comprising:
transmitting a signal that includes a value indicating a periodicity of discovery signal (DS) occasions; and
transmitting, within the DS occasion:
a cell-specific reference signal (CRS);
a primary synchronization signal (PSS); and
only one secondary synchronization signal (SSS), wherein for frame structure type 1, the PSS is transmitted in a first subframe of the DS occasion and for frame structure type 2, the PSS is transmitted in a second subframe of the DS occasion.
8. The method of claim 7 , wherein the periodicity is one of 40 milliseconds, 80 milliseconds, and 160 milliseconds.
9. The method of claim 7 , wherein the DS occasion comprises a period having a duration of:
one to five consecutive subframes for frame structure type 1, and
two to five consecutive subframes for frame structure type 2.
10. The method of claim 9 , wherein the DS comprises the CRS on antenna port 0 in a downlink subframe and in a subframe containing a Downlink Pilot Time Slot (DwPTS) of the DS occasion; and
wherein the DS further comprises a non-zero-power Channel State Information Reference Signal (CSI-RS) transmitted in zero or more subframes in the period.
11. The method of claim 7 wherein the PSS and the SSS are received within a same subframe of a sequence of subframes and wherein the PSS is received before the SSS within the subframe.
12. A non-transitory computer-readable medium including instructions that, when executed on an evolved Node-B (eNB), cause the eNB to perform operations including:
transmitting a signal that includes a value indicating a periodicity of discovery signal (DS) occasions; and
transmitting, within the DS occasion:
a cell-specific reference signal (CRS);
a primary synchronization signal (PSS); and
only one secondary synchronization signal (SSS), wherein for frame structure type 1, the PSS is transmitted in a first subframe of the DS occasion and for frame structure type 2 the PSS is transmitted in a second subframe of the DS occasion.
13. The non-transitory computer-readable medium of claim 12 , wherein the periodicity is one of 40 milliseconds, 80 milliseconds, and 160 milliseconds.
14. The non-transitory computer-readable medium of claim 12 , wherein the DS occasion comprises a period having a duration of:
one to five consecutive subframes for frame structure type 1, and
two to five consecutive subframes for frame structure type 2.
15. The non-transitory computer-readable medium of claim 14 , wherein the DS comprises the CRS on antenna port 0 in a downlink subframe and in a subframe containing a Downlink Pilot Time Slot (DwPTS) of the DS occasion; and
wherein the DS further comprises a non-zero-power Channel State Information Reference Signal (CSI-RS) transmitted in zero or more subframes in the period.
16. The non-transitory computer-readable medium of claim 12 wherein the PSS and the SSS are received within a same subframe of a sequence of subframes and wherein the PSS is received before the SSS within the subframe.