Method and apparatus for handling inter-modulation interference in a network node capable of FDD communications

A method of handling interference caused by inter-modulation in a network node site comprising co-located network nodes comprising a first network node and a second network node, wherein each co-located network node is for wireless communication and is capable of frequency division duplex communication with a set of stations for wireless communication, wherein the stations are wireless transceiver devices and communication from each of the network nodes to any of the respective stations is considered to be downlink communication performed on a downlink carrier frequency band and communication from any of the stations is considered to be uplink communication performed on an uplink carrier frequency band, the method comprising:

• detecting an interference level by the second network node on a transmission received on the associated uplink carrier frequency band for a subset of stations of the set of stations associated with the second network node;
• determining whether the interference level indicates probable inter-modulation interference;
• and
• if the interference level indicates probable inter-modulation interference:
• scheduling an uplink transmission grant for at least one of the stations of the subset of stations associated with the second network node, wherein the uplink transmission grant is valid for a first transmission time interval;
• transmitting the uplink transmission grant to the at least one station of the subset of stations associated with the second network node;
• assigning a transmit level at the first transmission time interval on a downlink carrier frequency band of the first network node that has a frequency relation to the uplink carrier frequency band on which the interference level indicated probable inter-modulation interference such that inter-modulation interference is reduced on the uplink carrier frequency band at the first transmission time interval;
• and
• receiving an uplink transmission from the at least one of the stations of the subset of stations associated with the second network node at the first transmission time interval.

A computer program product stored on a non-transitory computer readable medium and comprising program instructions that, when executed on a processor of a network node for wireless communication, causes the network node to handle the interference caused by inter-modulation in the network node, wherein the network node is capable of frequency division duplex communication with a set of stations for wireless communication, wherein the stations are wireless transceiver devices and communication from the network node to any of the stations is considered to be downlink communication performed on a downlink carrier in a downlink carrier frequency band and communication from any of the stations is considered to be uplink communication performed on an uplink carrier in an uplink carrier frequency band, and wherein the program instructions cause the network node to:

• detect an interference level on the uplink carrier frequency band for a subset of stations of the set of stations;
• determine whether the interference level indicates probable inter-modulation interference;
• and
• if the interference level indicates probable inter-modulation interference:
• schedule an uplink transmission grant for at least one station of the subset of stations, wherein the uplink transmission grant is valid for a first transmission time interval;
• transmit the uplink transmission grant to the at least one station of the subset of stations;
• assign a transmit level on the downlink carrier frequency band at the first transmission time interval such that inter-modulation interference is reduced on the uplink carrier frequency band at the first transmission time interval;
• and
• receive an uplink transmission from the at least one station of the subset of stations at the first transmission time interval.

A computer program product stored on a non-transitory computer readable medium and comprising program instructions that, when executed on a processor of a network node site controller, cause the network node site controller to handle interference caused by inter-modulation in a network node site, wherein the network node site comprises co-located network nodes comprising a first network node and a second network node, wherein each co-located network node is for wireless communication and is capable of frequency division duplex communication with a set of stations for wireless communication, wherein the stations are wireless transceiver devices and communication from each of the network nodes to any of the respective stations is considered to be downlink communication performed on a downlink carrier frequency band and communication from any of the stations is considered to be uplink communication performed on an uplink carrier frequency band, wherein the program instructions cause the network node site controller to:

• detect an interference level by the second network node on a transmission received on the associated uplink carrier frequency band for a subset of stations of the set of stations associated with the second network node;
• determine whether the interference level indicates probable inter-modulation interference;
• and
• if the interference level indicates probable inter-modulation interference:
• schedule an uplink transmission grant for at least one of the stations of the subset of stations associated with the second network node, wherein the uplink transmission grant is valid for a first transmission time interval;
• transmit the uplink transmission grant to the at least one station of the subset of stations associated with the second network node;
• assign a transmit level at the first transmission time interval on a downlink carrier frequency band of the first network node that has a frequency relation to the uplink carrier frequency band on which the interference level indicated probable inter-modulation interference such that inter-modulation interference is reduced on the uplink carrier frequency band at the first transmission time interval;
• and
• receive an uplink transmission from the at least one of the stations of the subset of stations associated with the second network node at the first transmission time interval.

A network node for wireless communication capable of frequency division duplex communication with a set of stations for wireless communication, wherein the stations are wireless transceiver devices and communication from the network node to any of the stations is considered to be downlink communication performed on a downlink carrier frequency band and communication from any of the stations is considered to be uplink communication performed on an uplink carrier frequency band, the network node comprising:

• an interference level detector circuit configured to detect an interference level on the uplink carrier frequency band for a subset of stations of the set of stations;
• and
• a controller circuit configured to determine whether the interference level indicates probable inter-modulation interference, wherein the controller is configured to, if the interference level indicates probable inter-modulation interference,
• schedule an uplink transmission grant for at least one of the stations of the subset of stations, wherein the uplink transmission grant is valid for a first transmission time interval;
• cause a transmitter of the network node to transmit the uplink transmission grant to the at least one station of the subset of stations;
• allocate a transmit level on the downlink carrier frequency band at the first transmission time interval such that inter-modulation interference is reduced on the uplink carrier frequency band at the first transmission time interval;
• and
• cause a receiver of the network node to receive an uplink transmission from the at least one station of the subset of stations at the first transmission time interval.

A network node site comprising co-located network nodes comprising a first network node and a second network node, each co-located network node is for wireless communication and capable of frequency division duplex communication with a set of stations for wireless communication, wherein the stations are wireless transceiver devices and communication from each of the network nodes to any of the respective stations is considered to be downlink communication performed on a downlink carrier frequency band and communication from any of the stations is considered to be uplink communication performed on an uplink carrier frequency band, the network node site comprising a network node site controller, wherein:

• the second network node is configured to detect an interference level on a transmission received on the associated uplink carrier frequency band for a subset of stations of the set of stations associated with the second network node;
• the network node controller is configured to determine whether the interference level indicates probable inter-modulation interference, wherein, if the interference level indicates probable inter-modulation interference,
• the second network node is configured to schedule an uplink transmission grant for at least one of the stations of the subset of stations associated with the second network node, wherein the uplink transmission grant is valid for a first transmission time interval, and is further configured to transmit the uplink transmission grant to the at least one station of the subset of stations associated with the second network node;
• and
• the first network node is configured to assign a transmit level at the transmission time interval on a downlink carrier frequency band of the first network node that has a frequency relation to the uplink carrier frequency band on which the interference level indicated probable inter-modulation such that inter-modulation interference is reduced on the uplink carrier frequency band associated with the second network node.