Methods Radio Network Nodes and User Equipment for Alleviating Interference in a Radio Communication Network

Patent metadata

Field	Value
Publication number	US-2016014791-A1
Application number	US-201314771730-A
Country	US
Kind code	A1
Filing date	Mar 14, 2013
Priority date	Mar 14, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

Methods and radio network nodes (BS 1 , BS 2 ) for alleviating interference on downlink radio signals in a victim User Equipment, UE (T 1 , T 2 ), caused by uplink transmission from an aggressor UE (T 2 , T 1 ). The interference occurs during a flexible subframe in which the direction of signal transmission is variable between uplink and downlink in different radio frames. A first radio network node (BS 1 ) detects ( 4:1 ) that a first UE (T 1 ) that is served by the first radio network node (BS 1 ) is one of the victim and aggressor UEs. The first radio network node (BS 1 ) identifies ( 4:2 ) a second radio network node (BS 2 ) employing a subframe scheme such that uplink transmission from the aggressor UE may overlap at least partly with downlink reception in the victim UE during the flexible subframe. The first radio network node (BS 1 ) sends ( 4:3 ) a notification to the second radio network node, indicating that the first UE is served by the first radio network node. The second radio network node (BS 2 ) is thereby triggered to execute ( 4:5 ) an interference mitigation action for alleviating the interference when serving a second UE (T 2 ) being the other one of the victim and aggressor UEs.

First claim

1 . A method, performed by a first radio network node in a radio communication network where subframes are transmitted in pre-determined positions within radio frames, wherein the first radio network node employs a subframe scheme where at least one of the pre-determined positions is allocated to a flexible subframe in which the direction of signal transmission is variable between uplink and downlink from one radio frame to another, for triggering mitigation of interference on downlink radio signals received by a victim User Equipment, UE, in a victim cell, said interference being caused by transmission of uplink radio signals from an aggressor UE in an aggressor cell during the flexible subframe, the method comprising:
detecting that a first UE, being one of the victim and aggressor UEs, is served by the first radio network node, identifying a second radio network node which employs a subframe scheme such that an uplink transmission from the aggressor UE potentially overlaps at least partly with downlink reception at the victim UE during the flexible subframe, and sending a notification to the identified second radio network node, the notification indicating the flexible subframe and the first UE being served by the first radio network node, to trigger the second radio network node to execute an interference mitigation action for alleviating said interference when a second UE, being the other one of the victim and aggressor UEs, is served by the second radio network node during the flexible subframe.

2 . A method according to claim 1 , wherein the subframe scheme employed by the second radio network node comprises a flexible subframe that overlaps at least partly in time with the flexible subframe of the first radio network node.

3 . A method according to claim 1 , wherein the notification is sent after determining that a level of said interference during the flexible subframe is higher than a threshold based on measurements of signals communicated to or from the first UE.

4 . A method according to claim 1 , wherein the first UE is detected when it is located in a cell border region of the first radio network node adjacent to a cell of the second radio network node.

5 . A method according to claim 4 , wherein the cell border region is determined based on measurements of path loss between UEs served by the first radio network node and the first radio network node.

6 . (canceled)

7 . A method according to claim 5 , wherein the determination of the cell border region is further based on additional measurements regarding the UEs served by the first radio network node, the additional measurements comprising measurements of at least one of: power headroom, transmit power, received signal strength, angle/direction of arrival, timing advanced, and one way propagation delay.

8 .- 10 . (canceled)

11 . A method according to claim 1 , wherein a set of neighbouring radio network nodes are identified which employ a direction of signal transmission during the flexible subframe that is opposite to the direction of signal transmission employed by the first radio network node during the flexible subframe, and further comprising sending the notification to one or more radio network nodes in the set of identified neighbouring radio network nodes.

12 . A method according to claim 1 , wherein when the first UE is the aggressor UE transmitting uplink radio signals with data during the flexible subframe, the first radio network node executes an interference mitigation action for alleviating said interference, the interference mitigation action comprising at least one of:
scheduling low data rate to the first UE in the uplink, decreasing transmission power of the first UE, using a more robust modulation scheme for the first UE, using a more robust coding scheme for the first UE, and using a more robust transport format for the first UE.

13 . A first radio network node in a radio communication network where subframes are transmitted in pre-determined positions within radio frames, the first radio network node being configured to employ a subframe scheme where at least one of the pre-determined positions is allocated to a flexible subframe in which the direction of signal transmission is variable between uplink and downlink from one radio frame to another, and to trigger mitigation of interference on downlink radio signals received by a victim User Equipment, UE, in a victim cell, said interference being caused by transmission of uplink radio signals from an aggressor UE in an aggressor cell during the flexible subframe, the first radio network node comprising:
a detecting unit configured to detect that a first UE, being one of the victim and aggressor UEs, is served by the first radio network node, an identifying unit configured to identify a second radio network node which employs a subframe scheme such that an uplink transmission from the aggressor UE potentially overlaps at least partly with downlink reception at the victim UE during the flexible subframe, and a sending unit configured to send a notification to the identified second radio network node, the notification indicating the flexible subframe and the first UE being served by the first radio network node, to trigger the second radio network node to execute an interference mitigation action for alleviating said interference when a second UE, being the other one of the victim and aggressor UEs, is served by the second radio network node during the flexible subframe.

14 . (canceled)

15 . A first radio network node according to claim 13 , wherein the sending unit is further configured to send the notification after it has been determined that a level of said interference during the flexible subframe is higher than a threshold based on measurements of signals communicated to or from the first UE.

16 . A first radio network node according to claim 13 , wherein the detecting unit is further configured to detect the first UE when it is located in a cell border region of the first radio network node adjacent to a cell of the second radio network node.

17 . A first radio network node according to claim 16 , wherein the detecting unit is further configured to determine the cell border region based on measurements of path loss between UEs served by the first radio network node and the first radio network node.

18 . (canceled)

19 . A first radio network node according to claim 17 , wherein the detecting unit is further configured to determine the cell border region based on additional measurements regarding the UEs served by the first radio network node, the additional measurements comprising measurements of at least one of: power headroom, transmit power, received signal strength, angle/direction of arrival, timing advanced, and one way propagation delay.

20 .- 22 . (canceled)

23 . A first radio network node according to claim 13 , wherein the identifying unit is further configured to identify a set of neighbouring radio network nodes which employ a direction of signal transmission during the flexible subframe that is opposite to the direction of signal transmission employed by the first radio network node during the flexible subframe, and the sending unit is further configured to send the notification to one or more radio network nodes in the set of identified neighbouring radio network nodes.

24 . A first radio network node according to claim 13 , wherein the first radio network node comprises a mitigation unit configured to, when the first UE is the aggressor UE transmittin

Assignees

• Ericsson Telefon Ab L M

Inventors

• Liu Jinhua
• Kazmi Muhammad

Classifications

• H04W52/365

  Power headroom reporting · CPC title

• H04W72/0446

  Resources in time domain, e.g. slots or frames · CPC title

• H04B7/2656 Primary

  for structure of frame, burst · CPC title

• H04W52/243

  taking into account interferences · CPC title

• H04W24/08

  Testing, {supervising or monitoring} using real traffic · CPC title