In 3GPP (3rd Generation Partnership Project), a W-CDMA scheme has been standardized as a third-generation cellular mobile communication scheme, and service has been sequentially started. HSDPA with higher communication speed has also been standardized and service has been carried out.
On the other hand, in the 3GPP, evolution of third generation radio access (Evolved Universal Terrestrial Radio Access; hereinafter referred to as “EUTRA”) has also been standardized, and service has been started. As a downlink communication scheme of the EUTRA, an OFDM (Orthogonal Frequency Division Multiplexing) scheme which is resistant to multipath interference and suitable for high-speed transmission has been employed. Moreover, a DFT (Discrete Fourier Transform)-spread OFDM scheme of single carrier frequency division multiple scheme SC-FDMA (Single Carrier-Frequency Division Multiple Access) capable of reducing a peak to average power ratio PAPR of a transmitted signal has been employed as an uplink communication scheme in consideration of cost and power consumption of a terminal device.
Further, in the 3GPP, working for standardizing Advanced-EUTRA, which is a further evolution from the EUTRA, is being carried out. It is assumed in the Advanced-EUTRA to use a band of up to 100-MHz bandwidth in each of uplink and downlink to perform communications with transmission rates of up to 1 Gbps or more in the downlink and 500 Mbps or more in the uplink.
In the Advanced-EUTRA, Heterogeneous Network (hereinafter, referred to as HetNet) is being considered in order to efficiently support communication traffic which is generated locally. The HetNet is a hierarchical network in which, in addition to a conventional macro cell, a small cell such as a pico cell or a femto cell is arranged so as to have a cell area overlapped with that of the macro cell (at a same frequency or a different frequency), which allows dispersion of communication traffic by mobile communication of a terminal device near the small cell which is present in the macro cell to the aforementioned small cell. Therefore, a mechanism by which a small cell is able to be detected efficiently by a terminal device which is present in a macro cell is being considered in the 3GPP (NPL 1).
USPTO Backgrounds
USPTO Backgrounds