In a UMTS (Universal Mobile Telecommunications System) network, long-term evolution (LTE) is under study for the purposes of further increasing high-speed data rates, providing low delay, and so on (non-patent literature 1). In LTE, as multiple access schemes, a scheme that is based on OFDMA (Orthogonal Frequency Division Multiple Access) is used in downlink channels (downlink), and a scheme that is based on SC-FDMA (Single Carrier Frequency Division Multiple Access) is used in uplink channels (uplink).
Furthermore, successor systems of LTE are also under study for the purpose of achieving further broadbandization and higher speed beyond LTE (referred to as, for example, “LTE-advanced” or “LTE enhancement” (hereinafter referred to as “LTE-A”)). In LTE-A (Rel-10), carrier aggregation to make a broad band by grouping a plurality of component carriers (CCs), where the system band of the LTE system is one unit, is used. Also, in LTE-A, a HetNet (Heterogeneous Network) configuration to use an interference coordination technique (eICIC: enhanced Inter-Cell Interference Coordination) is under study.
USPTO Backgrounds
USPTO Backgrounds