Single-frequency network (SFN) operation for machine-type communications (MTC) coverage enhancements
Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to techniques for single-frequency network (SFN) operation for machine-type communications (MTC) coverage enhancements. A method is provided for wireless communications by a user equipment (UE). The method generally includes detecting a synchronization signal transmitted from at least one of a plurality of transmission points, wherein each of the plurality of transmission points transmits a synchronization signal at a different offset time relative to a subframe boundary in a synchronized network, determining a subframe occurring a fixed time after detecting the synchronization signal to monitor for system information transmitted from at least one of the plurality of transmission points, and monitoring for a system information block during the determined subframe.
1. A method for wireless communications, by a user equipment (UE), comprising:
detecting at least one synchronization signal broadcasted in single frequency network (SFN) mode from a plurality of transmission points, the at least one synchronization signal providing timing for a subframe boundary in a synchronized network;
determining a subframe occurring a fixed time after detecting the at least one synchronization signal to monitor for system information transmitted from at least one of the plurality of transmission points;
monitoring for a system information block during the determined subframe; and
performing a random access channel (RACH) procedure with at least one of the plurality of transmission points.
2. The method of claim 1 , wherein performing the RACH procedure comprises transmitting a RACH message with extended transmission time interval (TTI) to the at least one of the plurality of transmission points.
3. The method of claim 1 , further comprising performing RACH at a fixed timing after system information block (SIB) transmission.
4. The method of claim 1 , wherein the UE is configured with a plurality of RACH configurations with different resource blocks (RBs).
5. The method of claim 4 , further comprising signaling information based on a RACH configuration used to perform the RACH procedure.
6. The method of claim 5 , wherein the RACH configuration used to perform the RACH procedure indicates at least one of a new service setup or urgency of the RACH procedure.
7. The method of claim 1 , wherein the plurality of transmission points comprise different groups of transmission points, each group associated with a different virtual cell ID.
8. The method of claim 1 , wherein a plurality of transmission points transmit system information in SFN mode.
9. The method of claim 1 , wherein different transmission points, corresponding to different cell IDs, transmit different system information.
10. The method of claim 1 , wherein the at least one synchronization signal is at least one of power boosted, transmitted with extended duration, or transmitted with narrow bandwidth.
11. The method of claim 1 , wherein the monitored system information block combines physical broadcast channel (PBCH) and SIB to convey actual system timing or system timing relative to a next machine-type communications (MTC) subframe.
12. A method for wireless communications, by a user equipment (UE), comprising:
detecting a synchronization signal transmitted from at least one of a plurality of transmission points, wherein each of the plurality of transmission points transmits a synchronization signal at a different offset time relative to a subframe boundary in a synchronized network;
determining a subframe occurring a fixed time after detecting the synchronization signal to monitor for system information transmitted from at least one of the plurality of transmission points; and
monitoring for a system information block during the determined subframe.
13. The method of claim 12 , further comprising performing a random access channel (RACH) procedure with at least one of the plurality of transmission points.
14. The method of claim 13 , wherein performing the RACH procedure comprises transmitting a RACH message with extended transmission time interval (TTI) to the at least one of the plurality of transmission points.
15. The method of claim 13 , wherein the UE receives, during the RACH procedure, a response indicating synchronized network timing.
16. The method of claim 13 , further comprising, after performing the RACH procedure:
entering a low power state during a plurality of subframes; and
exiting the low power state during subframes designated for communicating with the UE.
17. The method of claim 12 , wherein the synchronization signal comprises at least a portion containing a common sequence transmitted by each transmission point.
18. The method of claim 12 , wherein the plurality of transmission points comprise different groups of transmission points, each group associated with a different virtual cell ID.
19. An apparatus for wireless communications, by a user equipment (UE), comprising:
means for detecting at least one synchronization signal broadcasted in single frequency network (SFN) mode from a plurality of transmission points, the at least one synchronization signal providing timing for a subframe boundary in a synchronized network;
means for determining a subframe occurring a fixed time after detecting the at least one synchronization signal to monitor for system information transmitted from at least one of the plurality of transmission points;
means for monitoring for a system information block during the determined subframe; and
means for performing a random access channel (RACH) procedure with at least one of the plurality of transmission points.
20. The apparatus of claim 19 , wherein the means for performing the RACH procedure comprises means for transmitting a RACH message with extended transmission time interval (TTI) to the at least one of the plurality of transmission points.
21. The apparatus of claim 19 , further comprising means for performing RACH at a fixed timing after SIB transmission.
22. The apparatus of claim 19 , wherein the UE is configured with a plurality of RACH configurations with different resource blocks (RBs).
23. The apparatus of claim 22 , further comprising signaling information based on a RACH configuration used to perform the RACH procedure.
24. The apparatus of claim 23 , wherein the RACH configuration used to perform the RACH procedure indicates at least one of a new service setup or urgency of the RACH procedure.
25. An apparatus for wireless communications, by a user equipment (UE), comprising:
means for detecting a synchronization signal transmitted from at least one of a plurality of transmission points, wherein each of the plurality of transmission points transmits a synchronization signal at a different offset time relative to a subframe boundary in a synchronized network;
means for determining a subframe occurring a fixed time after detecting the synchronization signal to monitor for system information transmitted from at least one of the plurality of transmission points; and
means for monitoring for a system information block during the determined subframe.
26. The apparatus of claim 25 , further comprising means for performing a random access channel (RACH) procedure with at least one of the plurality of transmission points.
27. The apparatus of claim 26 , wherein the means for performing the RACH procedure comprises means for transmitting a RACH message with extended transmission time interval (TTI) to the at least one of the plurality of transmission points.
28. The apparatus of claim 26 , wherein the UE receives, during the RACH procedure, a response indicating synchronized network timing.