JP2006065700A - Radio communications system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce radio interference between mobile equipment and a cradle, and to improve a trade-off relation between electric power used in communication and a communication capacity. <P>SOLUTION: A radio communication device 1 for radio communication with the mobile equipment 11 using a radio wave is provided with a holding means 7 for holding the mobile equipment 11 detachably, and a holding detection means 5 for detecting the presence of the holding, and is radio-communicated with the mobile equipment 11 via both-side antennas 2, 2, when the presence of the holding in the mobile equipment 11 is detected by the holding detection means 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication system including a mobile device and a wireless communication device that performs wireless communication with the mobile device using radio waves.

In recent years, wireless LANs that do not require signal wiring by using radio waves have been widely used. For example, in a wireless LAN compatible with IEEE 802.11g, wireless communication is performed between an access point with a wireless communication function connected to wired Ethernet (registered trademark) such as 100BASE-T and a wireless LAN card mounted on a portable device or PC. Do.
FIG. 4 is a configuration diagram of a general wireless LAN device. Both the access point 41 and the portable device (or PC) 42 are provided with a transceiver 43 and an antenna 44.
The purpose of such a wireless LAN is to perform communication between remote information devices such as a PC, and it is an advantage over a wired LAN that it can be used regardless of location. Since the band and strength of radio waves that can be used in a wireless LAN are determined by laws and regulations such as the Radio Law, the signal strength becomes weaker as the communication distance becomes longer, and the signal gets closer to environmental noise and the communication speed decreases. There's a problem.
Also, in wired signal transmission, Gigabit Ethernet (registered trademark) and the like are becoming common, but wireless transmission is only about several hundreds Mbps even if UWB (Ultra Wideband) technology is used, and wireless transmission over wired communication. The speed difference does not shrink. When combined with wired transmission, there is a problem that the data transmission rate is limited by the slowest wireless transmission part.
On the other hand, cradle is often used in portable devices such as PDAs and cameras. A cradle is a device that synchronizes data between a PDA and a PC, or between a camera and a PC. When a device is placed in the cradle, the signal line is connected via a detachable connector provided in the cradle, and wired wirelessly. You can communicate and charge a battery built into your mobile device. It is widely used in various devices because it is convenient to perform data communication and data synchronization simply by placing a mobile device in the cradle and placing a sync button.
Although there is an example in which a cradle performs wireless communication, the communication speed is relatively low because the bandwidth and strength of a signal are limited by laws and regulations as in a wireless LAN. For example, a wireless mouse whose receiver is a cradle, and a “phone” made up of a parent device and a child device with a cradle provided with a function of charging a child device disclosed in Patent Document 1, for example, are known. .
The example in the above document uses two transmission bands for transmission and reception between the master unit and the slave unit, and a tank circuit that is composed of a forward winding coil and a reverse winding coil and does not resonate with respect to the transmission band is provided in front of the reception circuit. The transmission signal is prevented from being mixed.
Japanese Utility Model Publication No. 2-43048

Normally, the cradle and the mobile device placed in the cradle are connected by wire. Therefore, high-speed communication exceeding 100 Mbps is possible if the connector is compatible. On the other hand, since it is necessary to make contact with the connector, connection reliability such as poor contact due to rust of the connector, weakness in high humidity environment and lack of water resistance, and connection to the connector if not properly placed, etc. There is a problem in terms of convenience.
An object of the present invention is to reduce interference between a portable device and a cradle and to improve a trade-off relationship between power used for communication and communication capacity. It is another object of the present invention to achieve coexistence of proximity wireless and general wireless LAN.

In order to achieve the above object, a wireless communication system according to claim 1 includes a portable device and a wireless communication device that performs wireless communication with the portable device using radio waves, and the wireless communication device includes the portable device. A device-side antenna for performing wireless communication with the device-side antenna, a holding unit that detachably holds the portable device, and a holding unit that detects whether the portable device is held by the holding unit Detecting means, and when the holding detecting means detects that the portable device is held by the holding means, wireless communication is performed with the portable device via the device-side antenna. And
The wireless communication system according to claim 2 includes a portable device and a wireless communication device that performs wireless communication with the portable device using radio waves, and the wireless communication device is connected to a device-side antenna of the portable device. A device-side antenna for performing wireless communication with each other, a holding unit that detachably holds the portable device, a holding detection unit that detects whether the portable device is held by the holding unit, and the holding Changing means for changing a communication method of wireless communication with the portable device according to whether or not the portable device is held by the holding means by the detecting means. .
According to a third aspect of the present invention, in the wireless communication system, the holding means is surrounded by an absorber that absorbs radio waves in a communication band.
The wireless communication system according to claim 4 is characterized in that the device antenna and the device-side antenna are directional antennas, and are arranged so that the directions with high sensitivity face each other.
The radio communication system according to claim 5 is characterized in that the directional antenna is a planar type.
The wireless communication system according to claim 6 is characterized in that a plurality of device antennas and a plurality of device-side antennas are provided, and each antenna performs wireless communication independently.
The wireless communication system according to claim 7, wherein a power supply device is provided in each of the portable device and the wireless communication device, and when the portable device is held by the holding unit, the power supply device of the wireless communication device The mobile device is powered.

According to the invention of claim 1, since wireless communication is performed between the portable device and the wireless communication device that holds the portable device, interference is reduced, and the trade-off relationship between the power used for communication and the communication capacity is improved. A wireless communication apparatus with high quality, low power consumption, and high convenience can be configured.
According to the second aspect of the present invention, since the wireless device changes the communication method of the wireless communication between the holding state and the non-holding state so that the wireless LAN and the close proximity wireless device coexist. It is possible to provide a wireless communication device that can secure both the effects of high-speed and low-consumption transmission of proximity wireless communication.
According to the invention of claim 3, by enclosing the periphery of the antenna with an absorber having an absorption function for the communication radio wave band, a closed communication environment free from the influence of the outside world is provided between the portable device and the wireless communication device. Therefore, it is possible to perform optimal communication between the portable device and the wireless communication device using a communication method that does not depend on the outside world.
According to the invention of claim 4, by providing the mobile device and the wireless communication device with a directional antenna, the wireless communication has spatial selectivity, so that there is little influence of the outside world between the mobile device and the wireless communication device. Since a communication environment is provided, it is possible to perform optimal communication between a mobile device and a wireless communication device using a communication method that does not depend on the outside world.
According to the invention of claim 5, by using a planar directional antenna, the portable device equipped with the antenna and the wireless communication device are reduced in size and thickness. The device can be configured.
According to the invention of claim 6, since a plurality of antennas for wireless communication independently are provided and the wireless transmission speed is increased by spatially paralleling the transmission paths, wireless communication capable of large-capacity data communication is possible. The device can be configured.
According to the seventh aspect of the present invention, since power is supplied simultaneously with signal transmission by providing a power supply device for the wireless communication device and the portable device, the portable device and the wireless communication device using the conventional wired transmission are used. Can provide the same usability.

The wireless communication system of the present invention includes a portable device having a wireless communication function and a wireless communication device (hereinafter referred to as a cradle) connected to a network by wire or wirelessly and having the same wireless communication function and capable of holding the portable device. Wireless communication between them. Although the configuration is similar to a device that communicates between a mobile device and a cradle over a wireless LAN, the location of the mobile device that is the communication partner of the cradle cannot be specified in advance in the wireless LAN, whereas the configuration of this claim It communicates with the mobile device only when the mobile device is held. Therefore, the positions and directions of the other party are known in advance, and one-to-one communication with less interference is possible exclusively from other cradle and portable device. Further, since the mobile device and the cradle are close to each other (approximately several cm or less), the trade-off relationship between the power used for communication and the communication capacity is improved. This point will be described in detail below.
Shannon's formula that defines the capacity limit is described as follows.
C = Blog2 (1 + P / N) (Formula 1)
Here, C is the maximum communication capacity, B is the bandwidth, P is the average power of the received signal, N is the average power of noise, and log 2 is a logarithm with 2 as the base. If the bandwidth B and the average power N of noise are the same in the wireless LAN and this claim, the average power P of a signal that can be received increases because the communication distance is short. Therefore, high-speed communication becomes possible. Conversely, if the average power P that can be received is the same as that of the wireless LAN, the transmission power can be reduced. That is, the trade-off relationship between the power used for communication and the communication capacity is improved. The propagation delay of radio waves propagating through space is small, and the influence of signal delay is very small.
Compared to the conventional wired connection between the portable device and the cradle, in the present invention of claim 1, since the wireless connection is made, the alignment accuracy between the cradle and the portable device may be about several millimeters. When connecting by wire, it must be electrically connected via a connector, so a high connector shape accuracy of about several tens to 100 um is required, and communication is not possible unless the connector is completely inserted. There is no problem, and convenience for the user when holding the portable device is improved. Furthermore, in the case of wired connection, it is necessary to consider poor contact due to the rust of the electrode of the connector, but if it is wireless, there is no need to worry about that point, and a waterproof cradle can be easily configured .
Whether the portable device is held in the cradle can be detected by holding detection means provided in the cradle. As this holding detection means, a weight sensor for detecting the weight of the portable device, a mechanical sensor using a spring, an optical sensor for detecting reflected light on the surface of the portable device, or the like may be used.
There is no particular limitation on the wireless communication method between the portable device and the cradle, and an existing wireless standard may be used, or a new standard may be used. As long as it fits in the cradle, there are no restrictions on the applicable antenna or transceiver.

The wireless communication device of claim 2 differs from the wireless communication device of claim 1 in that it performs wireless communication not only when the portable device is held in the wireless communication device (hereinafter referred to as cradle) but also when it is not held. The communication method of wireless communication is changed depending on whether it is held. Therefore, if not held, the cradle can also function as a wireless access point of a portable terminal if a communication method compatible with a normal wireless LAN is adopted. When the portable device is held, there is an advantage that the operation can be switched to the low power consumption operation or the high speed operation as described in the first aspect.
According to a third aspect of the present invention, in the first and second aspects, the portable device and the cradle antenna are placed in a free space that is a waveguide. In this claim, the periphery of the waveguide is surrounded by an absorber for the communication radio wave band so that the radio wave does not leak outside the waveguide, and the reflection of the radio wave is suppressed inside the waveguide. If radio waves do not leak to the outside, communication within the waveguide can set the output and band of radio waves regardless of the radio standard, and can achieve high-speed communication (by increasing B and P in Equation 1, N can be reduced). If reflection is suppressed inside, communication between the mobile device and the cradle can reduce the effect of multipath, which can also speed up and simplify the communication method.
In the wireless communication device according to the fourth aspect, the mobile communication device and the wireless communication device are provided with directional antennas so that the wireless communication has spatial selectivity. For this reason, the one-to-one communication between the portable device and the wireless communication device is less affected by the external radio wave environment. It can be used together with claim 3 in the sense of a communication environment free from the influence of the outside world.

When applied to claim 1, since the position of the counterpart antenna is fixed, the direction of directivity may be fixed. When applied to Claim 2, it is desirable to be compatible with a wireless LAN when it is not held in the cradle, so an antenna that can change directivity is desirable.
In the wireless communication device according to the fifth aspect, by making the antenna planar, the occupied space can be narrowed compared to the antenna having a three-dimensional structure. Specifically, the mobile device and the cradle may be installed so that the planar antennas of the mobile device and the cradle face each other on the contact surface of the mobile device and the cradle.
In the wireless communication apparatus according to the sixth aspect, since each antenna can wirelessly transmit independently, it is equivalent to spatially paralleling the transmission paths and increasing the number of channels, thereby enabling high-speed wireless transmission.
According to another aspect of the wireless communication device of the present invention, when the portable device is held in the cradle, power is supplied to the portable device simultaneously with the communication. Since the portable device is operated by a battery or the like, if the battery can be charged when the portable device is held in the cradle in order to perform data synchronization or the like, a merit seen from the user is great. It is possible to provide the same usability as a conventional mobile device using wired transmission and a cradle, in which charging is automatically performed if the mobile device is periodically placed on the cradle for signal transmission. At this time, since the transmission is wireless, wireless power supply is also preferable. For example, a coil is installed on both the mobile device and the cradle to electrically couple them by electromagnetic induction, or the transmission power on the cradle side is increased, and a rectifier diode is installed on the receiving antenna on the mobile device side to rectify the received radio wave. A method (equivalent to a rectina for microwave power transmission) is conceivable.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Example 1]
FIG. 1 is a configuration diagram of a wireless communication device and a portable device according to the first embodiment. (1) shows a state where the portable device is not held in the cradle, and (2) shows a state where the portable device is held in the cradle. FIG.
In the wireless communication apparatus (cradle) 1 according to the present embodiment, a transmitter / receiver 4 including a tapered slot antenna 2 which is a planar antenna having directivity in the opening direction, a transmitter / receiver circuit 3, and a portable device 11 are held. A sensor (spring-type mechanical sensor) 5 and an interface controller 6 are provided, and a portable device 11 is fitted into the fitting portion 7 of the cradle 1.
Similar to the cradle 1, the portable device 11 is provided with a transceiver 4 including a tapered slot antenna 2 and a transceiver circuit 3, and the portable device 11 and the cradle 1 communicate with each other by the two transceivers 4 and 4. . The transceiver 4 on the cradle 1 side is connected to an external LAN via an interface controller 6. The interface controller 6 determines whether or not the portable device 11 is held in the cradle 1 by the sensor 5.
The mobile device 11 and the cradle 1 communicate with each other only when the mobile device 11 is held by the cradle 1, and the antennas 2 and 2 are very close to each other as shown in (2) (approximately several mm). In addition, since the direction having the directivity of the tapered slot antenna 2 is opposed, high-speed wireless transmission can be performed with low power consumption without interference with the outside.
[Example 2]
FIG. 2 is a configuration diagram of a wireless communication device and a portable device according to the second embodiment. The same portions as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
As shown in FIG. 2, in this embodiment, a wireless LAN transceiver 21 is provided in each of the cradle 1 and the portable device 11, and a coupling coil 22 that is electromagnetically coupled is used. By connecting the power feeding circuit 23 and connecting the rectifying circuit 24 to the coupling coil 22 on the portable device 11 side, wireless power feeding is performed from the cradle 1 side to the portable device 11 side.
The cradle 1 operates as a wireless access point using the wireless LAN transceiver 21 when the portable device 11 is not held. Similarly, the mobile device 11 communicates using the wireless LAN transceiver 21. In a state where the portable device 11 is held in the cradle 1, the wireless LAN transceivers 21 and 21 are disconnected, and close proximity wireless communication using the slot antennas 2 and 2 is performed.
At this time, the slot antennas 2 and 2 are close to each other, and there is no shortage of electric field strength due to multipath or radio wave dissipation. Therefore, high-speed wireless communication can be performed with lower power consumption than through a wireless LAN. it can. In addition, since it is completely wireless including the power source and no contact failure occurs, it is desirable in terms of reliability.

[Example 3]
FIG. 3 is a configuration diagram of the wireless communication device and the portable device according to the third embodiment. It is the figure which looked at the fitting part 7 of the bottom face of the portable apparatus 11 and the cradle 1 from diagonally. The same portions as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the present embodiment, the antenna array 31 in which the planar antennas of the first embodiment are arranged in parallel is arranged in parallel to the fitting surface of the cradle 1 and the portable device 11, and the periphery of the antenna array 31 is covered with a radio wave absorber. . The housing of the cradle 1 is made of a radio wave absorber such as a resin mixed with ferrite powder.
By absorbing unnecessary radio waves with the radio wave absorber, leakage of radio waves is suppressed when the mobile device 11 is held in the cradle 1, so that the mobile device 11 and the cradle have a power and wavelength band higher than those stipulated by laws and regulations. It is also possible to communicate between one and the transmission speed can be increased.
Since the antennas are arrayed, it is possible to perform two independent communications for each pair of antennas facing each other and to double the communication speed by simultaneously using the two systems. Further, since the planar antenna is arranged in parallel with the fitting surface, the use of the configuration of this embodiment has an advantage that the space between the cradle 1 and the portable device 11 can be utilized without waste.

It is a block diagram of the radio | wireless communication apparatus and portable apparatus of Example 1. FIG. FIG. 6 is a configuration diagram of a wireless communication device and a portable device according to a second embodiment. FIG. 6 is a configuration diagram of a wireless communication device and a portable device according to a third embodiment. It is a block diagram of a general wireless LAN device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus, Slot antenna, 3 Transmission / reception circuit, 4 Transmitter / receiver, 5 Sensor (holding detection means), 6 Interface controller, 7 Fitting part (holding means), 11 Portable apparatus

Claims (7)

  A mobile device and a wireless communication device that performs wireless communication with the mobile device using radio waves, and the wireless communication device includes a device-side antenna for performing wireless communication with a device-side antenna of the mobile device. A holding means for detachably holding the portable device, and a holding detection means for detecting whether or not the portable device is held by the holding means, and the portable device is connected to the holding means by the holding detection means. Wireless communication is performed with the portable device via the device-side antenna when it is detected that is held.   A mobile device and a wireless communication device that performs wireless communication with the mobile device using radio waves, and the wireless communication device includes a device-side antenna for performing wireless communication with a device-side antenna of the mobile device. A holding means for detachably holding the portable device, a holding detection means for detecting whether the holding device is held by the holding means, and the holding device holding the portable device by the holding detection means. A wireless communication system comprising: a changing unit that changes a communication method of wireless communication performed with the portable device according to whether or not the wireless communication device is used.   The wireless communication system according to claim 1 or 2, wherein the holding means is surrounded by an absorber that absorbs radio waves in a communication band.   The wireless communication system according to claim 1, wherein the device antenna and the device-side antenna are directional antennas and are arranged so that directions with high sensitivity face each other.   The wireless communication system according to claim 4, wherein the directional antenna is a planar type.   3. The wireless communication system according to claim 1, wherein a plurality of the device antennas and the device-side antennas are provided, and each antenna performs wireless communication independently.   A power supply device is provided in each of the portable device and the wireless communication device, and the portable device is powered by the power supply device of the wireless communication device when the portable device is held by the holding unit. Item 3. The wireless communication system according to Item 1 or 2.

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