Ntt Docomo, Inc.

Tomoyuki Ooya

Hiroki Harada

Takahiro Asai

Hitoshi Yoshino

Koji Maeda

Anass Benjebbour

Junichiro Hagiwara

Yusuke Ohwatari

Tatsuo Furuno

Takatoshi Sugiyama

Shinichi Mori

There is provided a communication system capable of achieving a high usage efficiency of frequencies without the need for cooperation of multiplexed users. A communication system communicates over frequency channels set by dividing a frequency bandwidth assigned to the system allows interference between channels by overlapping the adjacent frequency channels with each other in the frequency domain, or a transmitting and receiving device, which transmits and receives a signal by allowing the interference between symbols at a waveform level for each channel to decrease the occupied bandwidth, is provided with ICI removal and ISI compensation filterserving as either an ICI removal filter for removing the interference between channels or an ISI compensation filter for compensating the interference between symbols.

Communication system, transmitting device, receiving device, and communication method

A communication system capable of achieving a high usage efficiency of frequencies without the need for cooperation of multiplexed users is disclosed. The communication system communicates over frequency channels set by dividing a frequency bandwidth assigned to the system and allows interference between channels by overlapping the adjacent frequency channels with each other in the frequency domain. A transmitting and receiving device, which transmits and receives a signal by allowing the interference between symbols at a waveform level for each channel to decrease the occupied bandwidth, is provided. The receiving device is provided with an Inter-Channel Interference (ICI) removal and Inter-Symbol Interference (ISI) compensation filter serving as either an ICI removal filter for removing the interference between channels or an ISI compensation filter for compensating the interference between symbols.

Communication system, transmission device, reception device, and communication method

A disclosed radio communication apparatus transmits a radio signal to multiple users via multiple transmit antenna groups at appropriate transmit power levels, each of the transmit antenna groups including one or more transmit antennas, the transmit antenna groups having respective transmit power constraints. The apparatus includes a precoding unit configured to perform precoding on signals modulated for individual users and generate transmit weights, an optimum transmit power calculation unit configured to receive the transmit weights from the precoding unit and use components of the transmit weights and respective transmit power limit values for the transmit antenna groups to calculate an initial value for a transmit power optimization problem for calculation of the appropriate transmit power levels for the users, and a transmission unit configured to transmit radio signals at the calculated transmit power levels.

Radio communication apparatus and radio communication method

A disclosed radio communication apparatus includes a precoding unit, a optimum transmit power calculation unit and a transmission unit. The optimum transmit power calculation unit receives the transmit weight related information from the precoding unit and calculates a transmit power level to optimize an objective function in accordance with an interior point method. The objective function results from addition of a barrier function adjusted with a barrier parameter to an original objective function associated with a constrained optimization problem. The original objective function includes a function of respective channel capacities for individual users derived from the transmit weight related information. The optimum transmit power calculation unit adaptively updates a logarithm of the barrier parameter and uses a gradient obtained through a high-order derivative with the logarithm of the barrier parameter to calculate the transmit power level to optimize the resulting objective function.

A disclosed radio communication apparatus includes a preceding unit configured to precode multiple streams, a splitting unit configured to split the precoded streams into two or more stream sets each including one or more streams, a sub power optimization unit configured to execute an iterative transmit power optimization algorithm on each of the split stream sets to determine respective transmit power levels for the individual stream sets, a power optimization unit configured to execute the iterative transmit power optimization algorithm by using the determined transmit power levels as initial values for the iterative transmit power optimization algorithm to determine respective transmit power levels for the individual streams, and a transmission unit configured to transmit radio signals from individual transmit antennas at the determined transmit power levels.

A communication control device is provided which efficiently utilizes wireless resources to improve communication quality and system throughput by appropriately setting and performing node transmission power. The communication control device in a wireless LAN system includes a sender, a receiver, and an inter-AP communication functionfor determining, based on at least one of wireless information obtained by measurement of a wireless signal by an access pointor a station, or reported wireless information, whether or not there is a neighboring BSS, and a transmission power determination functionand a transmission power setting/update functionfor setting and updating the transmission power of the access pointand the stationin its own BSS when there is a neighboring BSS in which all the access point have the control function of the transmission power, on the other hand, for maximizing the transmission power when there is no neighboring BSS or when there is a neighboring BSS that does not control the transmission power.

Growing community of inventors

Yokohama, Japan

Tomoyuki Ooya