NEC Communication Systems LTD.

Satsumasendai, Japan

NEC Communication Systems LTD.

Satsumasendai, Japan
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Patent
NEC Communication Systems Ltd. | Date: 2015-08-03

A communication device includes a wireless communication unit, an in-transmission information generating unit, and a neighboring signal presence information generating unit. The wireless communication unit transmits and receives wireless frames via an antenna. The in-transmission information generating unit generates in-transmission information representing whether or not a wireless frame is being transmitted from the antenna. The neighboring signal presence information generating unit generates neighboring signal presence information representing whether or not a signal of a predetermined level or higher is present on a wireless channel that is the same as a wireless channel of the wireless frame. The collision detection unit determines a transmission end point of the wireless frame transmitted from the wireless communication unit based on the in-transmission information, determines whether or not there is a signal of the predetermined level or higher on the wireless channel through which the wireless frame is transmitted within a period from the determined transmission end point until a first time elapses, based on the neighboring signal presence information, and determines whether or not the transmitted wireless frame collided with another wireless frame, based on the determination made based on the neighboring signal presence information.


Patent
NEC Communication Systems Ltd | Date: 2014-05-23

The solution of the present invention is a precoding that allows an optimal use of multiple-antennas in a MIMO system. The precoding uses codebooks that are optimized for long-range wireless transmissions. A modified Kerdock codebook {w^(km)_(i)} allows further improvement of the precoding gain. The modified Kerdock codebook {w^(km)_(i)} contains new codewords w^(km)_(i )that have been modified in order to further improve the transmit bit error rate (BER). The modified codebook {w^(km)_(i)} allows a precoding gain that is between 2-3 dB. The present invention improves the transmit bit error rate (BER) of a wireless system. It allows a longer range in outdoor MIMO systems. Less signal outage is the result which allows that wireless signals can be transmitted over several kilometers.


Patent
NEC Communication Systems Ltd and NEC Corp | Date: 2014-09-05

A base station includes a wakeup signal transmission part transmitting transmission signal information to a wireless terminal by wireless communication. The transmission signal information includes a wakeup signal starting a given function included by the wireless terminal. The wakeup signal transmission part transmits the transmission signal information including connection information in addition to the wakeup signal to the wireless terminal. The connection information is information for causing the wireless terminal of a destination of transmission of the wakeup signal to connect by wireless communication using the given function.


Patent
Japan Advanced Telecommunications Research Institute International and NEC Communication Systems Ltd. | Date: 2015-08-21

When a terminal device initiates a wireless communication when it has not established a wireless link between itself and another wireless device, it transmits, as a management frames in active scanning, a plurality of activation probe requests having frame lengths representing an identifier of a wireless base station to which connection is being made and which is intended to transition from sleep mode to operating mode. Then, the wireless base station receives the plurality of activation probe requests transmitted by the terminal device as management frames in active scanning in a wireless LAN, and, when a plurality of dummy network identifiers detected based on the received plurality of activation probe requests represent the identifier of its own, transitions from sleep mode to operating mode.


Patent
NEC Communication Systems Ltd | Date: 2014-08-14

A wireless communication terminal has: a wireless module part which transmits a radio frame signal; a transmission loss information detection part which detects transmission loss information representing whether or not the radio frame signal transmitted by the wireless module part has reached a transmission destination; a collision information detection part which detects collision information representing an aspect of collision between the radio frame signal transmitted by the wireless module part and another radio frame signal; and a transmission control part which controls a transmission process executed by the wireless module part, on a basis of the transmission loss information and the collision information.


A wireless communication device includes a data transmission and reception section that wirelessly transmits a plurality of test packets; a signal sensing section that senses a power of a spatial radio wave signal on a frequency channel that is the same as the plurality of test packets and outputs sample data of the sensed spatial radio wave signal; a calculation processing section that converts the sample data into time series sample data; a collision detection section that calculates a packet collision rate based on the number of packet collisions and the number of the plurality of test packets if there is a packet collision due to interference of the plurality of test packets with another communication; and a control section that adjusts a parameter that the data transmission and reception section uses based on a calculation result of the collision detection section.


Patent
Japan Advanced Telecommunications Research Institute International and Nec Communication Systems Ltd. | Date: 2016-09-16

A wireless base station (1) includes a wakeup device (13) and a main device (14). When the main device (14) is in a sleep mode, the wakeup device (13) is connected to the antenna (11). Then, when the wakeup device (13) receives a wakeup signal for activating the wireless base station (1) from a terminal device assigned to the wireless base station (1) in a communication band used for wireless communication with the terminal device and when the information for identifying a wireless base station to be activated contained in the received wakeup signal is identical with the identification information of the wireless base station (1), the wakeup device (13) outputs a driving signal to the main device (14). The main device (14) transitions from the sleep mode to an operating mode in response to the driving signal from the wakeup device (13).


A transmission part transmits a packet by radio. A power detection part performs, at a given cycle, sampling of power of a spatial radio signal in a packet transmission period during which the transmission part transmits the packet. A collision detection part calculates, as an index value, at least one of the average value and the degree of variation of power of the spatial radio signal in the packet transmission period on the basis of sampled data obtained in the sampling by the power detection part. The collision detection part also determines a reference value on the basis of transmission power of the packet. Then, the collision detection part detects whether or not collision of the packet is present by comparing the index value with the reference value.


In order to solve a problem that, when a plurality of wireless communication modes are simultaneously used, interference between the plurality of wireless communication modes cannot be effectively prevented, a wireless communication control device according to the present invention includes a first communication mode control unit performing wireless communication in a first wireless communication mode, and a second communication mode control unit performing wireless communication in a second wireless communication mode. The second communication mode control unit detects a start of wireless communication in the first wireless communication mode, operates not to perform wireless communication in the second wireless communication mode during a wireless communication period in the first wireless communication mode, and operates to perform wireless communication in the second wireless communication mode outside a wireless communication period in the first wireless communication mode.


Patent
NEC Communication Systems Ltd., Kansai University and Japan Advanced Telecommunications Research Institute International | Date: 2015-09-15

A transmitter generates a header frame having a frame length indicating the beginning of data to be transmitted, data frames having frame lengths representing the data to be transmitted, and an end frame having a frame length indicating the end of the data to be transmitted. Then, for all of the header frame, data frames and end frame, the transmitter executes transmitting the kth frame when the wireless communication space is available, thereby transmitting the header frame, data frames and end frame, one after another, in accordance with the CSMA/CA scheme.

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