Nec Corporation

Lenovo Innovations Limited (Hong Kong)

Youko Omori

Shinichi Morimoto

Hideki Kurokawa

Makoto Zaitsu

Disclosed is a wireless LAN access point which has a detection means for detecting another wireless LAN access point; a handover timing adjustment means which makes a wireless LAN client under the control of the local wireless LAN access point transmit the handover information required to accommodate the other wireless LAN access point and adjust the handover timing with the other wireless LAN access point when it is judged whether or not a handover to the other wireless access point of the wireless LAN client under control can be executed and the handover is executed based on information relating to the other wireless LAN access point detected; and handover execution means for stopping the communication to the wireless LAN client at the adjusted timing.

Wireless LAN system, wireless LAN access point, handover execution method and program

A wireless LAN communication terminal and its communication control method are provided that make it possible to configure desired security between the terminal and an other-end terminal, without increasing power consumption of the terminals. The wireless LAN communication terminal () in a wireless LAN system including an access point (), if the other-end terminal () has connected to the access point, acquires from the other-end terminal information about security functions the other-end terminal has and information about a current connection with the access point; compares the security function information and the connection information on the other-end terminal with its own security policy; selects, based on results of the comparisons, either a direct connection () with the other-end terminal or a relay connection () via the access point so that the security policy is met; and performs communication with the other-end terminal by using the selected connection.

Wireless LAN communication terminal and communication control method thereof in wireless LAN system for the same

In terminal (-) for communicating with base station (-), threshold values (-to-) for searching a base station that will become to be a switching candidate are updated in accordance with the number of base stations which can communicate with terminal (-). In the base station that will become the switching candidate, the intensity or communication quality of a signal transmitted from base station (-) has been received by terminal (-) is previously set.

Wireless LAN system, wireless LAN terminal and base station searching method for such system and terminal

A power saving method in a wireless LAN system is disclosed for permitting a terminal station to promptly transition to a doze state irrespective of the presence or absence of data destined to the terminal station in a base station. Upon receipt of a PS-Poll signal from a terminal station subordinate to a base station for prompting a transmission of data destined to the terminal station, the base station transmits an ACK signal to the terminal station for indicating a successful reception of the PS-Poll signal. Further, the base station transmits a data frame including data destined to the terminal station when there is such data, or transmits an empty data frame when there is no data destined to the terminal station. Then, upon receipt of the data frame (including the empty data frame), the terminal station transmits an ACK signal to the base station, and then transitions to the doze state in which a transmission/reception function is made inoperative.

Power saving method in wireless LAN system for permitting terminal station to promptly transition to doze state by transmitting empty data frame

A signal estimator estimates a transmission signal series using Viterbi algorithm, and outputs an estimated signal and a minimum path metric signal. A switching unit is controlled by a control signal in such a manner that, for a certain period from the start of the operation of PLL which requires quick response, a minimum path metric history signal is selected, while, in the other case, an estimated signal is selected. A replica generator generates a replica signal using a signal output from the switching unit. The generation of the replica signal using the path metric history signal offers quick response, but on the other hand, the accuracy is low. On the other hand, the use of the estimated signal offers high accuracy, but on the other hand, the response speed is low. Thus, a phase change contained in a received signal is corrected in a highly accurate and quick manner.

Phase lock loop circuit using signal estimator

A uniform amplitude modulator includes in-phase component & quadrature component generation units and a modulated signal generation unit. The in-phase component & quadrature component generation units receive data represented by phase information and generate in-phase and quadrature components as analog signals. The modulated signal generation unit receives the in-phase and quadrature components and generates a modulated signal whose amplitude is uniform. One of the in-phase component & quadrature component generation units is constituted by a device for outputting an analog signal having any one of three, predetermined positive and negative values associated with the phase information, and 0. The other is constituted by a device for outputting an analog signal associated with the phase information.

Growing community of inventors

Tokyo, Japan

Youko Omori