Cooperating clusters in cellular communications systems

A method for establishing a cooperating cluster in a cellular communications system, the method being performed by a second network node, the method comprising:

• receiving a request for establishing a cooperating cluster from a first network node, the cooperating cluster comprising at least one cell of the first network node and at least one cell of the second network node, the request comprising a metric and identification of the cells to be clustered;
• evaluating acceptance of the request by verifying that an upper limit on allowed number of cooperations has not been reached and by comparing the metric to a metric of any on-going cooperating clusters involving the second network node;
• and
• as a result of said evaluation, transmitting, by the second network node, to the first network node one of:
• a first acceptance message and a second acceptance message, wherein
• the first acceptance message is a direct acceptance,
• the second acceptance message is a delayed acceptance,
• the second network node is configured to transmit the direct acceptance as a result of determining either that the acceptance would not cause operation of any on-going cooperating cluster involving the second network node to be discontinued or there are no such on-going cooperating clusters, and
• the second network node is further configured to transmit the delayed acceptance as a result of determining that the acceptance would cause operation of an on-going cooperating cluster involving the second network node to be discontinued.

A second network node for establishing a cooperating cluster in a cellular communications system, the second network node comprising:

• a receiver arranged to receive a request for establishing a cooperating cluster from a first network node, the cooperating cluster comprising at least one cell of the first network node and at least one cell of the second network node, the request comprising a metric and identification of the cells to be clustered;
• a processing unit arranged to evaluate acceptance of the request by verifying that an upper limit on allowed number of cooperations has not been reached and by comparing the metric to a metric of any on-going cooperating clusters involving the second network node;
• and
• in a case the acceptance does not cause operation of any previously established and still on-going cooperating clusters involving the second network node to be discontinued or in a case of no on-going cooperation:
• transmitting, by a transmitter, a direct acceptance of implementing the cooperating cluster to the first network node;
• or
• in a case the acceptance causes operation of at least one previously established and still on-going cooperating cluster involving the second network node to be discontinued:
• transmitting, by a transmitter, an acceptance resulting in delayed implementation of the cooperating cluster at the first network node to the first network node.