Method and Apparatus for Device-to-Device Synchronization Sequence Processing

Abstract

In one aspect of the teachings herein, a transmitter transmits synchronization signals according to one or more defined transmission characteristics that enable a receiver to distinguish the type of transmitter and/or the type of carrier used to convey the synchronization signals. Different types of transmitters reuse at least some of the same synchronization signal sequences and generation algorithms, but use different transmission parameters to impart one or more recognizable characteristics to the transmitted synchronization signals. In turn, an appropriately configured receiver “knows” which characteristics are associated with which transmitter and/or carrier types. For example, wireless devices operating in a wireless communication network transmit device-generated synchronization signals that reuse at least some of the same sequences used by network base stations for the transmission of network synchronization signals. However, device-generated synchronization signals are transmitted using a relative positioning or mapping that characteristically differs from that used for network synchronization signals.

What is claimed is: 
     
         1 . A method in a wireless device configured for operation in a wireless communication network, the method comprising:
 detecting synchronization signals received at the wireless device;   deciding from a relative positioning or mapping of the synchronization signals that the synchronization signals are device-generated synchronization signals originating from another wireless device, rather than network synchronization signals originating from a base station in the network, wherein the device-generated synchronization signals are generated using at least a subset of the same sequences as the network synchronization signals;   processing the synchronization signals according to processing procedures associated with the synchronization signals being decided to be device-generated synchronization signals;   receiving a Device-to-Device, D2D, broadcast control channel in association with the synchronization signals; and   detecting that one or more control fields in the D2D broadcast channel have been included or omitted, wherein the control field omissions or inclusions characteristically distinguish the D2D broadcast control channel from network broadcast control channel transmissions by any of the base stations in association with their respective transmissions of the network synchronization signals.   
     
     
         2 . The method of  claim 1 , wherein the processing procedures include attempting to decode a Physical Device-to-Device Synchronization Channel, PD2DSCH, that is transmitted when the synchronization signals are device-generated synchronization signals, and processing one or more parameters obtained from decoding the PD2DSCH. 
     
     
         3 . The method of  claim 1 , wherein the processing procedures include rules for synchronizing one or more timings of the wireless device with respect to device-generated synchronization signals. 
     
     
         4 . The method of  claim 1 , wherein the deciding that the device-generated synchronization signals are synchronization signals, rather than network synchronization signals is done from a relative positioning of the synchronization signals. 
     
     
         5 . The method of  claim 1 , wherein the synchronization signals include primary and secondary synchronization signals and wherein the step of deciding includes deciding that the synchronization signals are device-generated synchronization signals rather than network synchronization signals when a spacing or distance between the primary and secondary synchronization signals, as one aspect of said relative positioning, differs from a defined spacing or distance to be used by base stations operating in the Time Division Duplex, TDD, mode. 
     
     
         6 . The method of  claim 1 , wherein the synchronization signals include primary and secondary synchronization signals and wherein the step of deciding includes deciding that the synchronization signals are device-generated synchronization signals rather than network synchronization signals when an ordering of the primary and secondary synchronization signals, as another aspect of said relative positioning, differs from a defined ordering to be used by base stations operating in the Frequency Division Duplex, FDD, mode. 
     
     
         7 . The method of  claim 1 , wherein the synchronization signals include primary and secondary synchronization signals and wherein the step of deciding includes at least one of:
 deciding that the synchronization signals do not originate from a base station operating in Time Division Duplex, TDD, mode when a distance between the primary and secondary synchronization signals, as one aspect of said relative positioning, differs from a defined distance known to be used by base stations operating in the TDD mode; or   deciding that the synchronization signals do not originate from a base station operating in Frequency Division Duplex, FDD, mode when an ordering of the primary and secondary synchronization signals, as another aspect of said relative positioning, differs from a defined ordering known to be used by base stations operating in the FDD mode.   
     
     
         8 . A wireless device configured for operation in a wireless communication network and comprising:
 a communication interface configured for receiving signals from base stations in the network and from other wireless devices; and   a processing circuit that is operatively associated with the communication interface and configured to:
 detect synchronization signals received at the wireless device; 
 decide from a relative positioning or mapping of the synchronization signals that the synchronization signals are device-generated synchronization signals rather than network synchronization signals originating from any of the base stations, wherein the device-generated synchronization signals are generated using at least a subset of the same sequences as the network synchronization signals; and 
 process the synchronization signals according to processing procedures associated with the synchronization signals being decided to be device-generated synchronization signals; 
   wherein the processing circuit is configured to receive a Device-to-Device, D2D, broadcast control channel in association with the synchronization signals and detect that one or more control fields in the D2D broadcast channel have been included or omitted, wherein the control field omissions or inclusions characteristically distinguish the D2D broadcast control channel from network broadcast control channel transmissions by any of the base stations in association with their respective transmissions of the network synchronization signals.   
     
     
         9 . The wireless device of  claim 8 , wherein, according to the processing procedures, the processing circuit is configured to attempt to decode a Physical Device-to-Device Synchronization Channel, PD2DSCH, that is transmitted when the synchronization signals are device-generated synchronization signals, and to process one or more parameters obtained from decoding the PD2DSCH. 
     
     
         10 . The wireless device of  claim 8 , wherein according to the processing procedures, the processing circuit is configured to follow second rules for synchronizing one or more timings of the wireless device with respect to device-generated synchronization signals. 
     
     
         11 . The wireless device of  claim 8 , wherein the processing circuit is configured to decide that the synchronization signals are device-generated synchronization signals rather than network synchronization signals from a relative positioning of the synchronization signals. 
     
     
         12 . The wireless device of  claim 8 , wherein the synchronization signals include primary and secondary synchronization signals and wherein the processing circuit is configured to:
 decide that the synchronization signals do not originate from a base station operating in Time Division Duplex, TDD, mode when a spacing or distance between the primary and secondary synchronization signals, as one aspect of said relative positioning, differs from a defined spacing or distance known to be used by base stations operating in the TDD mode; or   decide that the synchronization signals do not originate from a base station operating in Frequency Division Duplex, FDD, mode when an ordering of the primary and secondary synchronization signals, as another aspect of said relative positioning, differs from a defined ordering known to be used by base stations operating in the FDD mode.