Methods and devices for cell discovery
This disclosure sets forth methods and devices for communication between mobile devices and base stations with active and dormant states. In an embodiment, a base station transmits system information during an active state of the base station with at least one system-information message. The at least one system-information message includes a SystemInformationBlockType1 (“SIB1”) message with a first update-indicator field. The base station selects an update value that indicates whether the system information has changed since a previous transmission of a previous SIB1 message. The base station transmits at least one dormant-state message during a dormant state of the base station with the selected update value in a second update-indicator field of the at least one dormant-state message.
1. A method in a mobile device for a long term evolution network, comprising:
receiving an identification signal from a cell;
selecting an extended physical cell identifier (E-PCID) from a first set of predetermined E-PCIDs based on the identification signal;
selecting a physical cell identifier (PCID) from a second set of predetermined PCIDs based on the E-PCID and a many-to-one mapping of the first set to the second set, wherein the first set is larger than the second set; and
receiving one or more communication signals from the cell based on the PCID.
2. The method of claim 1 wherein receiving the one or more communication signals comprises detecting one or more physical channels from the cell based on the PCID.
3. The method of claim 1 wherein receiving the one or more communication signals comprises detecting one or more reference signals from the cell based on the PCID.
4. The method of claim 1 wherein the PCID is a physical cell identifier of a macro cell that corresponds to the cell.
5. The method of claim 1 wherein receiving the identification signal comprises:
receiving a cell discovery signal from the cell when the cell is in a dormant state; and
receiving at least one physical channel from the cell when the cell is in an active state.
6. The method of claim 5 further comprising receiving the cell discovery signal from the cell when the cell is in both the dormant state and the active state.
7. The method of claim 1 wherein a size of the first set is an integer multiple of a size N of the second set, wherein selecting the PCID comprises determining a value of A modulo N where A is the E-PCID.
8. The method of claim 7 wherein the first set is distinct from the second set.
9. A method in a base station for a long term evolution network, the method comprising:
selecting, by the base station, a physical cell identifier (PCID) from a second set of predetermined PCIDs;
selecting an extended physical cell identifier (E-PCID) for the base station from a first set of predetermined E-PCIDs based on the PCID and a many-to-one mapping of the first set to the second set, wherein the first set is larger than the second set;
broadcasting an identification signal based on the E-PCID during a dormant state of the base station; and
broadcasting one or more communication signals based on the PCID.
10. The method of claim 9 wherein the identification signal is a cell discovery signal with a pilot sequence.
11. The method of claim 9 wherein a size of the first set is an integer multiple of a size N of the second set, wherein selecting the E-PCID comprises selecting a value A as the E-PCID such that A modulo N is equal to the PCID.
12. The method of claim 9 wherein the PCID is for a macro cell that corresponds to the base station.
13. The method of claim 9 wherein broadcasting the identification signal comprises broadcasting a cell discovery signal during the dormant state and an active state of the base station.
14. The method of claim 9 wherein a size of the second set is an integer multiple of a size of the first set.
15. The method of claim 14 wherein the second set is distinct from the first set.