Methods for Adapting Over-the-Air Synchronization to Radio Conditions

Abstract

Methods for enabling and disabling of muting patterns in Radio Access Network, RAN, nodes for the purpose of allowing better detection and use of reference symbols used for synchronization. An example method for facilitating over-the-air synchronization with a neighboring base station is implemented in a base station operating in a wireless communications network. The method comprises determining that a first neighbor cell of a plurality of neighbor cells is interfering with or is likely to interfere with a signal, from the second neighbor cell, that is used for synchronization. The method further comprises sending, towards the first neighbor cell and in response to said determining, a request for activation of a reference signal muting pattern by the first neighbor cell.

What is claimed is: 
     
         1 . A method, in a base station operating in a wireless communications network, for facilitating over-the-air synchronization with a neighboring base station, the method comprising:
 identifying a first neighbor cell as a desired over-the-air synchronization source, based on at least one of a stratum level or synchronization status of the first neighbor cell;   determining that a signal being transmitted by a second neighbor cell is interfering with or is likely to interfere with a reference signal transmitted by the first neighbor cell and needed by the base station for synchronization; and   sending towards the second neighbor cell, in response to said determining, a request for activation of a reference signal muting pattern by the second neighbor cell.   
     
     
         2 . The method of  claim 1 , further comprising subsequently determining that the reference signal from the first neighbor cell is not needed or is unavailable for synchronization and, in response, sending a message, towards the second neighbor cell, indicating that the reference signal muting pattern may be deactivated. 
     
     
         3 . The method of  claim 1 , wherein the request for activation is sent to a controlling node in the wireless communications network, wherein the controlling node controls a base station corresponding to the second cell. 
     
     
         4 . The method of  claim 1 , further comprising receiving synchronization information from at least the first neighbor cell, the synchronization information indicating at least one of the stratum level and synchronization status, wherein said identifying is based on the received synchronization information. 
     
     
         5 . The method of  claim 1 , further comprising receiving an indication of whether a reference signal muting pattern is available for the second neighbor cell, wherein said sending of the request is responsive to receiving said indication. 
     
     
         6 . The method of  claim 5 , wherein the indication comprises or is associated with an identification of one or more muting patterns available for the second neighbor cell. 
     
     
         7 . The method of  claim 1 , wherein the request for activation of the reference signal muting pattern includes an identification of one or more resources that should be muted, the identification of one or more resources that should be muted identifying a subframe pattern, or a pattern periodicity, or both. 
     
     
         8 . The method of  claim 1 , further comprising receiving, in response to said request, information identifying which resources are being muted or are to be muted by the second neighbor cell. 
     
     
         9 . A base station apparatus comprising:
 a communications interface circuit configured to communicate with one or more other base stations or with one or more control nodes, or one or more of each; and   a processing circuit configured to control the communications interface circuit and further configured to
 identify a first neighbor cell as a desired over-the-air synchronization source, based on at least one of a stratum level or synchronization status of the first neighbor cell; 
 determine that a signal being transmitted by a second neighbor cell is interfering with or is likely to interfere with a reference signal transmitted by the first neighbor cell and needed by the base station for synchronization; and 
 send towards the second neighbor cell, in response to said determining, a request for activation of a reference signal muting pattern by the second neighbor cell. 
   
     
     
         10 . The base station apparatus of  claim 9 , wherein the processing circuit is further configured to subsequently determine that the signal from the first neighbor cell is not needed or is unavailable for synchronization and, in response, send a message towards the second neighbor cell, via the communications interface circuit, the message indicating that the reference signal muting pattern may be deactivated. 
     
     
         11 . The base station apparatus of  claim 9 , wherein the processing circuit is further configured to receive synchronization information from at least the first neighbor cell, the synchronization information indicating at least one of the stratum level and synchronization status, and to identify the first neighbor cell as a desired over-the-air synchronization source based on the received synchronization information. 
     
     
         12 . The base station apparatus of  claim 9 , wherein the processing circuit is further configured to receive, via the communications interface circuit, an indication of whether a reference signal muting pattern is available for the second neighbor cell, wherein said sending of the request is responsive to receiving said indication. 
     
     
         13 . The base station apparatus of  claim 12 , wherein the indication comprises or is associated with an identification of one or more muting patterns available for the second neighbor cell. 
     
     
         14 . The base station apparatus of  claim 9 , wherein the request for activation of the reference signal muting pattern includes a list of cells for which a muting pattern should be applied. 
     
     
         15 . The base station apparatus of  claim 9 , wherein the request for activation of the reference signal muting pattern includes an identification of one or more resources that should be muted. 
     
     
         16 . The base station apparatus of  claim 15 , wherein the identification of one or more resources that should be muted comprises a subframe pattern, or a pattern periodicity, or both. 
     
     
         17 . The base station apparatus of  claim 9 , wherein the processing circuit is further configured to perform synchronization based on the signal from the first neighbor cell. 
     
     
         18 . The base station apparatus of  claim 9 , wherein the processing circuit is further configured to receive, via the communications interface circuit, information identifying which resources are being muted or are to be muted by the second neighbor cell.