Baseband unit and method of obtaining information on a remote radio unit and another baseband unit connected to the remote radio unit supporting the operation of the remote radio unit

A baseband unit (BBU) obtaining information regarding a remote radio unit (RRU) in a heterogeneous cell environment in which a macro cell and a small cell coexist, the BBU comprising:

• a transmitter,
• a receiver, and
• a processor, coupled to the transmitter and receiver, which controls a serving RRU, wherein the processor further:
• controls the receiver to receive a measurement report message, from a user equipment (UE) through the serving RRU corresponding to the UE, wherein the serving RRU is connected to the BBU, wherein the measurement report message contains information regarding a target RRU transmitting a reference signal to the UE with a strength equal to or greater than a threshold value, and wherein the target RRU is connected with and physically separated from a second BBU, and the second BBU performs L1/L2/L3 layer processing for the target RRU, and
• controls the receiver to receive information the second BBU,
• performs a coordination procedure regarding interference control with the second BBU or supports handover of the UE from the serving RRU to the target RRU using the information the second BBU, and
• wherein a mapping relation between RRUs and BBUs is time-varying and based on at least one of load of the BBUs and an available resource status of the BBUs.