Method and arrangement in a telecommunication system

Abstract

Method and apparatus for avoiding or reducing interference between transmissions from a donor eNB to a relay node and downlink transmissions from the relay node to at least one mobile terminal, where the transmissions take place in overlapping frequency bands. In the method, at least one interruption is created in a transmission from the relay node to the mobile terminal(s), and during the created interruption, a transmission from the donor eNB is received. This may result in an improved reception of the transmission from the eNB in the relay node.

1 . A method for operating a relay node in a wireless communication system, wherein the system includes an evolved Node B (eNB) for sending first transmissions to the relay node, the relay node being adapted for sending second transmissions to at least one mobile terminal connected to the relay node, the first and second transmissions taking place in overlapping frequency bands, the method comprising the steps of:
 creating at least one interruption in said second transmissions from the relay node to the at least one mobile terminal; and,   receiving, by the relay node, first transmissions from the eNB during said at least one interruption.   
     
     
         2 . The method according to  claim 1 , wherein the at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format for the second transmissions. 
     
     
         3 . The method according to  claim 1 , wherein said at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format that is backwards compatible with legacy mobile terminals. 
     
     
         4 . The method according to  claim 1 , wherein said at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format in which the subframe contents are limited to reference symbols and control signalling, which are allocated in less than 3 OFDM symbols of the subframe. 
     
     
         5 . The method according to  claim 1 , wherein the subframes of the transmission from the eNB to the relay node are time-shifted one or more OFDM symbol durations relative to the subframes of the second transmissions. 
     
     
         6 . The method according to  claim 5 , wherein the number of OFDM symbol durations of the time shift is selected based on the duration of a control region used in subframes within the cells of the relay node. 
     
     
         7 . The method according to  claim 5 , wherein a last part of at least one subframe of the first transmissions from the eNB to the relay node is left unused for transmission. 
     
     
         8 . The method according to  claim 7 , wherein the time length of the unused part depends on the number of OFDM symbol durations of the time shift of the subframe. 
     
     
         9 . The method according to  claim 1 , wherein the number of said interruptions of the second transmissions can vary from several interruptions per radio frame to less than one interruption per radio frame. 
     
     
         10 . The method according to  claim 1 , wherein the relay node decides at which point in time the interruptions should be created; and, wherein the relay node informs the concerned mobile terminals and, if necessary, the eNB during which time interval an interruption will be created in the second transmissions. 
     
     
         11 . The method according to  claim 1 , wherein the relay node is informed by the eNB of at which point in time the interruptions should be created; and, wherein the relay node informs the concerned mobile terminals during which time interval an interruption will be created in the second transmission. 
     
     
         12 . A relay node for a wireless communication system, the relay node adapted to receive first transmissions from an evolved Node B (eNB), the relay node further adapted to send second transmissions to at least one mobile terminal connected to the relay node, wherein the first and second transmissions take place in overlapping frequency bands, said relay node comprising:
 an interference avoiding unit adapted to create at least one interruption in said second transmissions from the relay node to the at least one mobile terminal; and,   a receiving unit adapted to receive first transmissions from the eNB during said at least one interruption.   
     
     
         13 . The relay node according to  claim 12 , wherein said at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format. 
     
     
         14 . The relay node according to  claim 12 , wherein the interference avoiding unit is further adapted to create said at least one interruption by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format that is backwards compatible with legacy mobile terminals. 
     
     
         15 . The relay node according to  claim 12 , wherein the interference avoiding unit is further adapted to create said at least one interruption by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format in which the subframe contents are limited to reference symbols and control signalling, which are allocated in less than 3 OFDM symbols of the subframe. 
     
     
         16 . The relay node according to  claim 12 , wherein the receiving unit is further adapted to receive subframes of the first transmissions from the eNB to the relay node, which are time-shifted one or more OFDM symbol durations relative to the subframes of the second transmissions. 
     
     
         17 . The relay node according to  claim 16 , wherein the receiving unit is further adapted to receive subframes in which the number of OFDM symbol durations of the time shift is selected based on the duration of a control region used in subframes within the cells of the relay node. 
     
     
         18 . The relay node according to  claim 16 , wherein the receiving unit is further adapted to receive subframes in which a last part of at least one subframe of the first transmissions from the eNB to the relay eNB is left unused for transmission. 
     
     
         19 . The relay node according to  claim 18 , wherein the receiving unit is further adapted to receive subframes in which the time length of the unused part depends on the number of OFDM symbol durations of the time shift of the subframe. 
     
     
         20 . The relay node according to  claim 12 , wherein the interference avoiding unit is further adapted to being able to vary the number of said interruptions from several interruptions per radio frame to less than one interruption per radio frame. 
     
     
         21 . The relay node according to  claim 12 , wherein the relay node is adapted to decide at which point in time the interruptions should be created; and, wherein the relay node is further adapted to inform the concerned mobile terminals and/or the eNB during which time interval an interruption will be created in the second transmissions. 
     
     
         22 . The relay node according to  claim 12 , wherein the relay node is adapted to receive, from the eNB, information about at which point in time the interruptions should be created, and/or wherein the relay node is further adapted to inform the concerned mobile terminals during which time interval an interruption will be created in the second transmissions. 
     
     
         23 . An arrangement for operating in a wireless communication system comprising:
 an evolved Node B (eNB) controlling a donor cell; and,   a relay node;
 wherein the eNB is adapted to send first transmissions to the relay node, and the relay node is adapted to send second transmissions to at least one mobile terminal connected to the relay node, the first and second transmissions taking place in overlapping frequency bands; and, 
 wherein the relay node is configured to:
 create at least one interruption in second transmissions to the mobile terminal(s); and, 
 receive first transmissions from the eNB controlling the donor cell during said at least one interruption. 
 
   
     
     
         24 . An evolved Node B (eNB) for a wireless communication system, the eNB adapted to send first transmissions to a relay node, which is adapted to send second transmissions to a least one terminal connected to the relay node, wherein the first and second transmissions take place in overlapping frequency bands, the eNB being further adapted to send first transmissions to the relay node during an interruption of the second transmissions. 
     
     
         25 . The evolved Node B according to  claim 24 , wherein the at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format for the second transmissions. 
     
     
         26 . The evolved Node B according to  claim 24 , wherein said at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format that is backwards compatible with legacy mobile terminals. 
     
     
         27 . The evolved Node B according to  claim 24 , wherein said at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format in which the subframe contents are limited to reference symbols and control signalling, which are allocated in less than 3 OFDM symbols of the subframe. 
     
     
         28 . The evolved Node B according to  claim 24 , wherein the eNB is adapted to time-shift subframes of the first transmissions from the eNB to the relay node for one or more OFDM symbol durations relative to the subframes of the second transmissions. 
     
     
         29 . The evolved Node B according to  claim 28 , wherein the number of OFDM symbol durations of the time shift is selected based on the duration of a control region used in subframes within the cells of the relay node. 
     
     
         30 . The evolved Node B according to  claim 24 , wherein a last part of at least one subframe of the first transmissions from the eNB to the relay node is left unused for transmission. 
     
     
         31 . The evolved Node B according to  claim 30 , wherein the time length of the unused part depends on the number of OFDM symbol durations of the time shift of the subframe. 
     
     
         32 . The evolved Node B according to  claim 24 , wherein the number of said interruptions of the second transmissions can vary from several interruptions per radio frame to less than one interruption per radio frame. 
     
     
         33 . The evolved Node B according to  claim 24 , wherein the relay node decides at which point in time the interruptions should be created; and, wherein the relay node informs the concerned mobile terminals and the eNB during which time interval an interruption will be created in the second transmissions, wherein the eNB is adapted to receive corresponding information from the relay node and/or to send first transmissions based on such information. 
     
     
         34 . The evolved Node B according to  claim 24 , the eNB being adapted to determine at which point in time the interruptions should be created and/or to inform the relay node about the determined point in time. 
     
     
         35 . A method for operating an evolved Node B (eNB) in a wireless communication system, wherein the eNB sends first transmissions to a relay node, which is adapted to send second transmissions to a least one terminal connected to the relay node, wherein the first and second transmissions take place in overlapping frequency bands, and the eNB sends first transmissions to the relay node during an interruption of the second transmissions. 
     
     
         36 . The method according to  claim 35 , wherein the at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format for the second transmissions. 
     
     
         37 . The method according to  claim 35 , wherein said at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format that is backwards compatible with legacy mobile terminals. 
     
     
         38 . The method according to  claim 35 , wherein said at least one interruption is created by using a Multicast/Broadcast Single Frequency Network (MBSFN) subframe format in which the subframe contents are limited to reference symbols and control signalling, which are allocated in less than 3 OFDM symbols of the subframe. 
     
     
         39 . The method according to  claim 35 , wherein the eNB time-shifts the subframes of the first transmissions from the eNB to the relay node for one or more OFDM symbol durations relative to the subframes of the second transmissions. 
     
     
         40 . The method according to  claim 35 , wherein the number of OFDM symbol durations of the time shift is selected based on the duration of a control region used in subframes within the cells of the relay node. 
     
     
         41 . The method according to  claim 35 , wherein a last part of at least one subframe of the first transmissions from the eNB to the relay node is left unused for transmission. 
     
     
         42 . The method according to  claim 41 , wherein the time length of the unused part depends on the number of OFDM symbol durations of the time shift of the subframe. 
     
     
         43 . The method according to  claim 35 , wherein the number of said interruptions of the second transmissions can vary from several interruptions per radio frame to less than one interruption per radio frame. 
     
     
         44 . The method according to  claim 35 , wherein the eNB is adapted to receive, from the relay node, information about in which time interval an interruption will be created in the second transmissions, and/or wherein the eNB sends first transmissions based on such information. 
     
     
         45 . The method according to  claim 35 , wherein the eNB determines at which point in time the interruptions should be created and/or informs the relay node about the determined point in time.