Hitachi, Ltd.

Kingo Miyoshi

Mikio Kuwahara

Tsuyoshi Tamaki

Tomoya Yokota

Shuji Otsubo

An optimum communication mode and an optimum antenna are selected according to traffic and a radio propagation status of a terminal. With the use of traffic information between a base station and the terminal, an SISO communication or an SIMO communication is conducted if the traffic is small. It is determined whether the MIMO communication should be conducted, or not, if the traffic is large. An antenna that can exert the effect as the MIMO communication is selected by using the radio propagation channel state information between the distributed antennas of the base station and the antenna of the terminal. Also, because the selection of the antenna is changed by conducting the MIMO communication, an antenna optimum for the terminal that conducts the SISO communication or the SIMO communication is re-selected taking the interference influence on the terminal that conducts the SISO communication or the SIMO communication into account.

Distributed antenna system, base station device, and antenna selection control method

In a transmission apparatus in a MIMO-OFDM communication system employing cyclic diversity, a cyclic delay controller sets plural delay magnitudes, different for respective antennas, in cyclic delayers for each predetermined timing. The cyclic delayers receive symbols subjected to orthogonal frequency division multiplexing, for the respective ones of plural allotted antennas. Additionally, the cyclic delayers bestow cyclic delays on the individual symbols of the respective antennas in accordance with plural set delay magnitudes. The symbols cyclically delayed are outputted from the antennas. As the delay magnitudes, a first delay magnitude at a first transmission timing and a second delay magnitude at a second transmission timing are different for one antenna, and the delay magnitudes differ in the respective antennas for one transmission timing. Thus, in a MIMO-OFDM transmission scheme, frequency diversity and time diversity are enhanced to heighten a retransmission efficiency in a data retransmission mode.

Transmission apparatus, access point and symbol transmission method

A base station and a router are interactively connected by a multilink group which transmits VoIP packets and a multilink group which transmits data packets other than VoIP packets. The base station and the router split transmission lines by referencing the ToS area of received packets and transmit only VoIP packets by way of a dedicated line. In this way, VoIP packets can be transmitted without being affected by other data packets, and the quality of VoIP can be warranted on the mobile network.

Growing community of inventors

Yokohama, Japan

Kingo Miyoshi