Takahiko Saba

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Artificial noise (AN) is one of physical layer security techniques, which can realize secure communication. AN is a noise signal which is intentionally transmitted from transmitter along with data signals. Since AN is generated to be canceled out at legitimate receivers, it can prevent eavesdroppers from eavesdropping even if transmitters do not know the(More)
Turbo-code is known as the powerful error correcting code. The principle of turbo-code, which is the concatenated convolutional code, makes it possible to control the code rate by the use of the puncturing. When the puncturing is applied, the reliability of the decoded bits is not uniform over a frame, because some bits are decoded using only received(More)
The recent Long Term Evolution (LTE) standard only supports hard handover to reduce both the signaling overhead among base stations and the complexity of the LTE network architecture. In LTE-Advanced, coordinated multi-point (CoMP) is expected to improve the cell edge throughput and system throughput. Since a user equipment can have connections with(More)
In this paper, we propose a channel estimation method for radio frequency multiple-input multiple-output orthogonal frequency division multiplexing (RF–MIMO–OFDM) systems. In RF–MIMO–OFDM systems, a receiver combines the received signals at the RF front-end. This implies that a receiver can estimate only one of MIMO channels during one OFDM symbol duration.(More)
The occurrence of the intercell interference (ICI) is inevitable in downlink heterogeneous networks because user terminals (UTs) often receive the signals transmitted from different base stations (BSs) at the same time. To mitigate ICI, a hierarchical interference alignment (HIA) is proposed. HIA is based on the interference alignment (IA), which aligns the(More)