Disclosed systems and methods mitigate interference in heterogeneous networks. Embodiments include adaptive or selective inter-cell interference coordination, adaptive multi-user zero forcing, adaptive power, and/or combinations of the foregoing. Techniques may be used to favor one group of users (e.g., femto users or macro users) over another. Certain embodiments focus quality of service (QoS) improvements on a first group of users, while using constraint processes to provide a threshold QoS for a second group of users.

A new approach to deployment of a hybrid node in a cellular communication network is proposed, wherein the hybrid node includes a plurality of antennas that simultaneously serve a plurality of cells in the cellular communication network by transmitting or receiving signals to or from the cells at the same time. The cellular communication network further includes a partner cell among the plurality of cells served by the hybrid node, wherein the partner cell is a soft cell that maintains communication channels with antennas of more than one node at the same time. The cellular communication network further includes a hybrid cell among the plurality of cells also served by the hybrid node, wherein the hybrid cell is a hard cell that maintains communication channels with antennas of only one node at any one time. The partner cell and the hybrid cell have different cell-ids and they each connects to and serves a plurality of user equipment (UE) for uplink communication to and downlink communication from the hybrid node.

In the wireless communication system, each of a base station 11 and a terminal station 12 obtains its location information, and upon establishment of synchronization, the terminal station 12 transmits a terminal station free channel list and its location information by extremely low power wireless communication, and the base station 11 compares a base station free channel list created based on information from a database 40 with the terminal station free channel list from the terminal station 12, and determines, when there is a common free channel, the free channel as uplink/downlink channels and determines, when there is no common free channel, an uplink channel and a downlink channel as different channels, calculates a base station-terminal station distance from the location information of the base station 11 and the location information of the terminal station 12, and determines terminal station's uplink transmission power based on the distance.

A method for identifying a mobile cell causing interference by a terminal connected to a first mobile cell, according to one embodiment of the present invention, comprises the steps of: acquiring system information of a fixed base station to which the first mobile cell is connected through a backhaul interface; acquiring a physical cell identifier of a second mobile cell neighboring the first mobile cell by a cell search; determining whether the second mobile cell causes interference to the first mobile cell on the basis of the physical cell identifier of the second mobile cell and the system information of the fixed base station; and reporting the physical cell identifier of the second mobile cell to the first mobile cell if the interference to the first mobile cell is determined to be caused by the second mobile cell.

The present disclosure is characterized by including the steps of: obtaining a resource pool for use in D2D communication in a wireless communication system, wherein the resource pool includes at least one of a scheduling assignment (SA) resource pool that represents a resource region to which the SA is transmitted, or a data resource pool that represents a resource region to which D2D data is transmitted; transmitting SA including information related to D2D data transmission to a second terminal through the SA resource pool; and transmitting D2D data to the second terminal.

Embodiments of the present invention disclose a power estimation method and apparatus. On a premise of controlling interference caused by a second node to a first node to be within a range, a transmit power of the second node can be increased so as to improve communication quality of the second node. A specific solution is: obtaining an estimated load value of each first node in N first nodes according to a transmit power and user service requirements of each first node that are obtained and according to a transmit power set for each second node in M second nodes, and further, respectively using the transmit power set for each second node as an allowed transmit power of each second node according to the estimated load value of each first node in the N first nodes.

According to certain aspects, resources allocated to a user equipment (UE) for physical uplink control channel (PUCCH) transmissions may be determined in a subframe-type dependent manner. As a result, PUCCH regions for different subframes may vary based on the subframe types.

A picocell base station (PeNB) uses a downlink control channel, the frequency band of which overlaps with the frequency band of the downlink control channel used by a macrocell base station (MeNB), to transmit downlink control information for controlling radio communication with a radio terminal (PUE) connected to the picocell base station (PeNB). The picocell base station (PeNB) comprises an X2 interface communication unit (140) which uses inter-base station communication to transmit to the macrocell base station (MeNB) usage control information for controlling the control channel usage that is the usage of a radio resource used as the downlink control channel by the macrocell base station (MeNB).

A method of conveying transmit power information from a first cell to a second cell is provided. The first cell prepares a data structure including a plurality of elements, each element corresponding to a respective downlink subframe in a radio frame associated with the first cell and its value corresponding a respective minimum transmit power reduction level promised by the first cell during the downlink subframe. The first cell then transmits the data structure to the second cell via a predefined interface. The second cell processes the data structure and schedules one or more user equipments in one or more downlink subframes of the radio frame in accordance with the data structure.

One embodiment is directed to a method for operating base stations in a heterogeneous network. The method may include receiving, by a first base station, an indication for a second base station to use flexible time division duplex mode (502), assessing an amount of interference that will be caused by the second base station (504)-(508), deciding how to adjust a transmission power of the second base station (509), and sending the second base station a request to adjust the transmission power (510).