Ntt Docomo, Inc.

Ntt Mobile Communications Network, Inc.

Toshiyuki Futakata

Sung Uk Moon

Shinji Uebayashi

Tomohiro Dohi

Takayuki Ishiguro

Hiroyuki Ishii

Takahiro Hayashi

Makoto Ito

Mayu Yamada

Yoshiaki Hiramatsu

Masatoshi Kimoto

Takanori Utano

Masayuki Furusawa

Tsutomu Taguchi

Taro Ishikawa

Seiko Shimizu

There is provided a mobile station that minimizes a pause or a silent period during communication at the time of a reconnection process of communication, thereby to improve the user's convenience and achieve the reduction in the load applied onto the communication network or the mobile station. When an out of synchronization detection unitof a mobile stationdetects out of synchronization, an individual timer value determination unitselects two or more timer value change triggers from timer value change triggers stored in a timer value change trigger memory, and then determines the timer values respectively for the timer value change triggers that have been selected, based upon the determination rules stored in an individual timer value determination rule memory. A reconnection timer value calculation unitcalculates an appropriate reconnection timer value based upon the two or more individual timer values that have been determined by the individual timer value determination unit. A timer switching control unitsets the reconnection timer value, and a timer management unitactivates a timer. When the timer expires, a radio communication unittransmits a reconnection request.

Mobile station and method of reconnection process

There is provided a control device enabling switching of communication of a mobile terminal with one system to communication with another system while reducing power consumption and workload of the mobile terminal. The control device is used in a communication system including a first mobile communication system, a second mobile communication system, and a mobile terminal being in communication with the first mobile communication system. The control device comprises a position measuring unit for measuring the position of the mobile terminal, a judgment unit for making a determination whether or not to switch the communication of the mobile terminal from the first mobile communication system to the second mobile communication system according to a position measurement result of the position measuring unit, and a switching unit for performing the above switching operation according to the determination of the judgment unit.

Control device of mobile communication system

A modulation device comprises a modulation unit () that modulates data in a hierarchical manner using multiple types of modulation techniques, and a transmission unit () that transmits the hierarchically modulated data. A demodulation device comprises a receiving unit () that receives the hierarchical modulation data having been subjected to hierarchical modulation using multiple types of modulation techniques, and a demodulation unit () that demodulates the hierarchical modulation data using a demodulation technique corresponding to a specific hierarchy of the hierarchical modulation data.

Modulation and demodulation based on hierarchical modulation

The present invention relates to a spreading signal assigning method and a signal transmitting method in a direct sequence CDMA mobile communication system, a mobile wireless communication system using the methods, and a transmitter, a receiver and a transceiver in the mobile wireless communication system in which an assignment method of a second spreading code is devised such that various services can be provided. The invention is configured such that a signal spread with the second spreading code is transmitted between a base station and a mobile station by assigning a code associated with each base station group or a code associated with each network type to which the base station group belongs as the second spreading code.

Method of assignment and transmission of spread signals in direct sequence spread spectrum CDMA mobile communication system, mobile communication system, and transmitter, receiver and transmitter/receiver of mobile communication system

The present invention provides a radio base station for preventing degradation of transmission quality characteristics even when there are time differences between the instant of channel estimation of uplink time slots UL#to UL#N and the instant of transmission of transmission data via downlink time slots DL#to DL#N. The radio base station includes transmit diversity controllerstofor controlling transmit diversity to be used for downlink time slots DL#to DL#N and a data transmitterfor transmitting data via downlink time slots DL#to DL#N using the controlled transmit diversity.

Radio base station and method of controlling radio communications

The present invention provides a radio base station using the conventional downlink transmit diversity which can compensate for the degradation of transmission quality even when a plurality of users (mobile terminals) share a single time slot using a code division multiple system. The radio base station includes a channel estimatorfor performing channel estimation of an uplink time slot; a transmit diversity controllertofor controlling the transmit diversity used for downlink time slots DLto DL#N based on said channel estimation and the number of users sharing the downlink time slot when using a code division multiple system; a data transmitterfor transmitting data via downlink time slots DLto DL#N using the controlled transmit diversity.

There is provided a radio communication device able to adaptively adjust a pilot symbol insertion rate and improve efficiency of channel estimation and data transmission. It comprises a channel estimation unit that performs the channel estimation using the pilot symbols, a storage unit that stores a plurality of estimated values obtained by the channel estimation unit, a determination unit that compares the estimated values stored in the storage unit and determines an amount of change of the estimated values, and a notification unit that notifies the pilot symbol insertion unit of the amount of change of the estimated values.

Radio communication device and method thereof

A mobile station receives a signal based on a TDD method by receiving a signal based on a FDD method to acquire information of the signal based on the TDD method in a mobile communication system. For instance, the mobile station receives a signal based on a CDMA-FDD method. Then, the mobile station acquires information (e.g. information relating to a code, a frequency and a timing) of a signal based on a CDMA-TDD method from the signal based on the CDMA-FDD method. Then, the mobile station receives the signal based on the CDMA-TDD method on the basis of the acquired information.

Mobile station, base station and communication method

The adaptive modulation method for use in a mobile communication system employing a TDMA scheme associates a modulation scheme with each time slot within a frame, and modulates transmission data of a communication channel using the modulation scheme associated with the time slot into which the communication channel is assigned.

Adaptive modulation method, radio network controller, and mobile communication system

A channel assigning method and a communication apparatus for executing appropriate channel assignment in a mobile communication system when both a channel for a service area based on a FDD method and a channel for a service area based on a TDD method can be assigned are provided. For example, if both a channel for a service area based on a CDMA-FDD method and channels for service areas based on a CDMA-TDD method can be assigned to a request for channel assignment, and a handover frequency of the mobile station related to the request is high, the channel for the service area based on the CDMA-FDD method is assigned.

Channel assigning method and communication apparatus

When a mobile station communicates with a base station by way of one or a plurality of other mobile stations, the mobile station acting as a relay station determines whether the data demodulated after being received is reception data for the mobile station or transfer data to be transmitted to the other mobile station or the base station, decides a modulation mode suitable for transmitting sum data of the transfer data and transmission data if the transmission data is generated in the mobile station, and transmits the sum data while modulating the sum data according to the modulation mode decided. The base station demodulates a reception signal relayed by the mobile stations according to the modulation mode of the mobile station having directly communicated with the base station, and identifies each user data multiplexed.

Mobile station used as a repeater station when communicating with a base station

In a mobile communication system, interference power from adjacent cells is effectively reduced and transmission power is limited. A transmission loss estimation unitand a transmission power estimation unitestimate transmission power necessary for transmission of a downstream signal. According to an upstream signal from each of plurality of mobile terminal devices to a base station, a grouping unitdivides a plurality of mobile terminal devices into groups sharing a plurality of wireless resources according to the estimated transmission powers. Downstream signals to be transmitted to mobile terminal devices belonging to each of the groups formed by the grouping means are transmitted simultaneously with each other. Also, priorities are set for the plurality of wireless resources and the mobile terminal devices belonging to the groups divided by the grouping unitare assigned according to the set priorities. Accordingly, transmission to one of the groups requiring higher transmission power in one of cells adjacent to each other and transmission to one of the groups requiring higher transmission power in another of the cells are performed at different times, thereby reducing interference power received in each cell from the adjacent cells.

Mobile communication system, base station apparatus, and method of controlling mobile communication system

A mobile phonereceives a home cell signal sent from a base station Band a foreign cell signal sent from a base station Bor from a mobile phonein a foreign cell A. The mobile phonereceives spreading codes C&#x2013;Csent from the base station B, as home cell codes. The mobile phonedetects the interference between the home cell signal and the foreign cell signal. When the interference is detected, the mobile phonereceives a spreading code Csent from the base station Bor from the mobile phone, as a foreign cell code. The mobile phonecancels an interference signal by joint detection, using the home cell codes and the foreign cell code.

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Yokosuka, Japan

Toshiyuki Futakata