JP2004222136A - Wireless communication system and access point controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system which can simultaneously access different wired networks, that is, a first access point to be connected to video/audio equipment and a second access point to be connected to a public network through a gateway, even if a wireless terminal has only one wireless communication means. <P>SOLUTION: Through the first access point 11, each wireless terminal accesses a set top box 16 or a digital video device 17 as a video/audio equipment to be connected to the first access point 11 to receive downloading of a video content. Simultaneously, the terminal accesses the Internet via the first point 11 utilizing inter-access-point communication between the first access point 11 and the second access point 12, and performing connection to the public network 52 through the second point 12. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, when a plurality of access points with a wired network exist in the same wireless network, the access points perform communication between the access points, so that the wireless terminal only communicates with any one of the access points. The present invention relates to a wireless communication system capable of accessing respective wired networks via a plurality of access points. Further, the present invention relates to an access point control device applied to such a wireless communication system.
[0002]
[Prior art]
In recent years, broadband Internet access lines and wireless LAN devices have been rapidly spread, and to cope with the streaming distribution of moving image content to wireless terminals and the increase in the number of terminals accommodated in wireless LAN networks, the speed and scale of wireless LANs have been increasing. There is a demand for increased capacity.
[0003]
Also, with the speeding-up of wireless LANs, not only applications such as simply accessing the Internet using wireless LANs, but also connecting wireless LAN devices to video and audio equipment such as set-top boxes and videos, Devices have been developed in which broadcast program contents received in a box or video contents recorded in video or the like are converted into a format such as MPEG2, transmitted wirelessly, and viewed on a display or the like on a wireless terminal side.
[0004]
FIG. 5 shows a configuration of a wireless network in which a wireless terminal accesses an Internet network or a video / audio device via a public network in the related art.
[0005]
In FIG. 5, reference numeral 100 denotes a wireless network, 101 denotes a first access point for a wireless terminal, and 102 denotes a second access point, which are connected to each other via a wired cable 109. Further, a set top box 106 and a digital video 107 are connected to the first access point 101. The set-top box 106 receives a terrestrial television broadcast, a BS broadcast or a CS broadcast from the broadcast receiving antenna 151, and converts the broadcast program content as it is or into a digital stream format such as an MPEG2 transport stream to obtain a first access point. To the digital video 107.
[0006]
The bridge model 108 is connected to the second access point 102 as a gateway, and can access the Internet via the public network 152.
[0007]
The wireless terminals 103 to 105 are wirelessly connected to a first access point 101 and a second access point 102, respectively. Each of the wireless terminals 103 to 105 is a personal computer, a portable information terminal, or a display having a wireless communication function.
[0008]
In the wireless network 100 configured as described above, the operation of each access point and wireless terminal will be described.
[0009]
The wireless terminal 103 connects to the second access point 102 to access the Internet, and accesses the Internet via the public network 152.
[0010]
The wireless terminal 104 connects to the first access point 101 to view the television broadcast content, and issues a request to the set-top box 106 to distribute the video content received from the broadcast receiving antenna 151. The set-top box 106 converts the video content received from the broadcast receiving antenna 151 into the MPEG2 transport stream format, and transmits it to the first access point 101. The first access point 101 packetizes the received MPEG2 transport stream for wireless transmission, and transmits the packet to the wireless terminal 104. When receiving the packet transmitted by the first access point 101, the wireless terminal 104 restores the packet to the original MPEG2 transport stream, decodes the packet into video content, and views the video content on the attached display.
[0011]
Then, it is assumed that the wireless terminal 105 accesses the Internet and simultaneously receives the video content received by the set-top box 106. The method of receiving the video content is the same as that of the wireless terminal 104. To access the Internet, it is necessary to connect to the second access point 102 to access the public network. However, since the wireless terminal 105 receives the distribution of the video content from the set-top box 106, the wireless terminal 105 is restricted to be connected to the first access point 101. Therefore, in order to access the Internet, it is necessary to make a wired connection to the second access point 102 via the first access point 101 via the wired cable 109, and to connect to the public network 152.
[0012]
[Patent Document 1]
JP-A-2001-156804 (page 3, FIG. 1-2)
[0013]
[Problems to be solved by the invention]
However, in a general home, the antenna terminal for television broadcasting and the modular terminal of the telephone line are installed at separate places, so that the wiring of the wired cable 109 connecting the access points becomes long, and the There is a problem that spoils the aesthetics of people.
[0014]
Therefore, a measure can be considered in which the wired cable 109 connecting the access points is eliminated and the wireless terminal is configured to be able to communicate with both access points. However, in this case, in a method using the same wireless communication channel, it is difficult to process synchronization information included in control information from both access points, and it is very difficult to synchronize with both access points.
[0015]
On the other hand, in a method using different wireless communication channels, the wireless terminal needs to have two types of wireless communication means, and the circuit scale of the wireless terminal is increased, and the cost is increased.
[0016]
The present invention has been made in view of such circumstances, and even if a wireless terminal has only one wireless communication unit, a first access point connected to a video / audio device and a gateway are provided. It is an object of the present invention to provide a wireless communication system capable of simultaneously accessing different wired networks with a second access point connected to a public network via the public network.
[0017]
[Means for Solving the Problems]
In order to solve the above problems, the present invention takes the following measures. That is, a first access point connected to a video / audio device that receives or stores image / audio information, a second access point connected to a public network via a gateway, and at least one wireless terminal. Assume a wireless network including In such a wireless network, the first access point wirelessly communicates information from the video / audio device to the wireless terminal in a packet system in accordance with an access request from the wireless terminal to the video / audio device. In addition, the communication between the wireless terminal and the second access point is relayed by packet-based wireless communication in accordance with an access request to the public network from the wireless terminal. The communication channel of the wireless transmission path between the first access point and the second access point is different from the communication channel of the wireless transmission path between the first access point and the wireless terminal. Set to channel.
[0018]
The operation of this configuration is as follows. The wireless terminal issues an access request to both the video / audio device and the public network using a single wireless communication channel, and downloads information. Therefore, the wireless terminal may be a single wireless communication means, and the burden on the applicable wireless terminal can be reduced. Further, as the second access point connected to the public network, the conventional access point can be used as it is, and the cost burden is reduced. Furthermore, even if there is a single wireless communication channel, time-division processing can be performed by the packet method, so that simultaneous access of the video / audio device and the public network is possible. And even if the first access point and the second access point are installed apart from each other, the two access points are connected by a wireless transmission path, and a wired cable is eliminated, which impairs the appearance. Without having to do so, both video and audio equipment and the public network can be accessed.
[0019]
In one of the preferred aspects described above, the wireless communication scheme between the first access point and the second access point is a wireless communication scheme between the first access point and the wireless terminal. The same system can be mentioned. However, different wireless communication schemes may be used.
[0020]
In a preferred embodiment of the above, the format of a packet on a wireless transmission path between the first access point and the second access point is a wireless transmission path between the first access point and the wireless terminal. It is common to the packet of the path and has a destination address, a relay destination address, a relay source address, and a source address in the header portion. By using a packet of such a format, high-speed access is enabled, and the first access point connected to the video / audio device can be set as a priority relay station.
[0021]
Further, the present invention employs the following solution for the access point control device constituting the first access point in the above wireless communication system. That is, the access point control device of the present invention performs wireless communication with a wireless terminal using a wired interface for connecting a video / audio device that receives or stores image / audio information and a first wireless communication channel. A first wireless communication means for performing wireless communication with an access point connected to a public network via a gateway using a second wireless communication channel; Wireless protocol control means for routing packets transmitted and received to and from the second wireless communication means.
[0022]
The operation of this configuration is as follows. When the destination of the access request from the wireless terminal received by the first wireless communication unit is a video / audio device, connection with the video / audio device is performed via a wired interface by routing of the wireless protocol control unit, and the first When the access request destination from the wireless terminal received by the wireless communication means is the public network, the access request is switched to the second wireless communication means by the routing of the wireless protocol control means, relayed to the second access point, and Make a connection with Accordingly, the wireless terminal to which the present invention is applied may be a single wireless communication means, and the second access point connected to the public network may use the conventional wireless terminal as it is. It is possible, and the cost burden can be reduced. Then, even if the first access point and the second access point are far apart, it is possible to access both the video / audio device and the public network with the wired cable that impairs the appearance removed.
[0023]
As a preferable embodiment in the above, the modulation method of the first and second wireless communication means may be OFDM (Orthogonal Frequency Division Multiplex). When OFDM is used as a modulation method for wireless communication, the influence of reflected waves can be removed in a wireless propagation environment such as at home where there are many effects of reflected waves, and especially when transmitting a high bit rate stream such as moving image content. Transmission characteristics can be improved.
[0024]
If the wired interface is IEEE1394, high-speed and high-quality video information can be obtained.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a wireless communication system according to the present invention will be described in detail with reference to the drawings.
[0026]
FIG. 1 is a block diagram illustrating a configuration of a wireless communication system according to an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a target wireless network, reference numeral 11 denotes a first access point for connecting a video / audio device that receives or stores image / audio information, and a set-top box as an example of the video / audio device. 16 and digital video 17 are connected. Here, a set-top box and digital video are mentioned as examples of the video / audio equipment, but a digital video player such as a DVD player or a personal computer for storing and managing video content may be used. Reference numeral 12 denotes a second access point connected to the public network 52 via a gateway. In FIG. 1, the second access point is connected to the public network 52 via the bridge modem 18 as an example of the gateway. As the gateway, an ADSL modem is used when the public network 52 is ADSL, an ONU is used when the public network 52 is FTTH, and a DSU and a terminal adapter are used when the public network 52 is ISDN.
[0027]
The set-top box 16 receives a terrestrial broadcast, a BS broadcast, and a CS broadcast via the broadcast receiving antenna 51, and converts the received broadcast program content into a digital stream format such as an MPEG2 transport stream when the received broadcast program content is an analog signal. The data is converted and transmitted to the first access point 11 or a program is recorded on the digital video 17. Here, the digital stream format is not particularly defined.
[0028]
The first access point 11 is wirelessly connected to the wireless terminals 13 to 15 and is wirelessly connected to the second access point 12 via a wireless transmission path 53. Here, the wireless terminals 13 to 15 are personal computers, portable information terminals or displays having a wireless communication function.
[0029]
The wireless communication method and the wireless control method between the first access point 11 and the second access point 12 and the wireless communication method and the wireless control method between the first access point 11 and the wireless terminals 13 to 15 are: The respective systems may be the same system or different systems, but different wireless communication channels are used for the wireless communication channels. Note that it is preferable to use OFDM as a modulation method of wireless communication because the influence of reflected waves can be removed in a wireless propagation environment where the effects of reflected waves are large, such as at home. Particularly, when transmitting a high bit rate stream such as moving image content, the transmission characteristics are improved.
[0030]
FIG. 2 shows a configuration of the access point control device 20 which forms the first access point 11 for connecting video / audio equipment.
[0031]
Reference numeral 21 denotes a first wireless communication unit that transmits and receives a packet to and from a wireless terminal via an antenna 21a. Reference numeral 22 denotes a wireless protocol process such as a configuration of a packet transmitted by the first wireless communication unit 21, division, error retransmission, and transmission timing control. Is a second wireless communication means for transmitting and receiving packets to and from another access point via an antenna 23a, and 24 is a configuration and division of a packet transmitted by the second wireless communication means 23. This is a second wireless control unit that performs wireless protocol processing such as error retransmission and transmission timing control. Reference numeral 25 denotes routing means for routing a packet based on a destination address of a packet received by the first wireless control means 22, a packet received by the second wireless control means 24, or a packet transmitted from the bridging means 28, and 26 denotes an access point, a wireless terminal, This is a terminal information management table for managing information on video / audio equipment. The first wireless control unit 22, the second wireless control unit 24, the routing unit 25, and the terminal information management table 26 constitute a wireless protocol control unit 27. ing. 28 converts a packet processed by the wire protocol control means 29 and a packet processed by the wireless protocol control means 27.
[0032]
Reference numeral 29 denotes a wired protocol control unit, and reference numeral 30 denotes a wired communication unit, which can use, for example, IEEE 1394 or Ethernet (registered trademark). When the wire is IEEE1394, the wire communication means 30 performs the function of the physical layer of IEEE1394, and the wire protocol control means 29 performs the function of the link layer and the transaction layer of IEEE1394.
[0033]
The access point control device in the second access point 12 has the same internal configuration as the access point control device 20 in the first access point 11, but includes only one set of wireless control means and wireless communication means.
[0034]
FIG. 3 shows a configuration of a packet 40 transmitted and received between access points or between a wireless terminal and an access point. 41 is a header, 42 is a payload, and 43 is a CRC (Cyclic Redundancy Check). The header 41 includes at least a destination address 44, a relay destination address 45, a relay source address 46, and a source address 47, and further includes a packet type and the like. Video contents and Internet data are inserted into the payload 42. CRC 43 is a cyclic code used for error correction.
[0035]
The operation of the wireless communication system configured as described above will be described below.
[0036]
In the initial state, only the terminal information of the first access point 11 itself is registered in the terminal information management table 26 of the access point control device 20 constituting the first access point 11. Here, the terminal information is information such as a terminal address and a currently used wireless communication channel. Similarly, for the second access point 12, only the terminal information of the second access point 12 itself is registered in the terminal information management table.
[0037]
When the first access point 11 connects the set top box 16 and the digital video 17 to the wired network, the addresses and functions of these devices are registered in the terminal information management table 26. If the format of the address is different from that on the wireless side, the address is virtually allocated and registered in accordance with the address format on the wireless side.
[0038]
First, the second access point 12 periodically transmits a synchronization packet using a predetermined wireless communication channel to confirm whether or not another wireless terminal exists in the wireless network 10. Upon receiving the synchronization packet transmitted by the second access point 12 via the wireless transmission path 53, the first access point 11 returns a registration request packet to the second access point 12. When receiving the registration request packet transmitted by the first access point 11 via the wireless transmission path 53, the second access point 12 registers the address of the first access point 11 and the wireless communication channel in the terminal information management table. I do. Thereafter, the first access point 11 and the second access point 12 communicate using a wireless communication channel specifying the wireless transmission path 53.
[0039]
Next, the first access point 11 communicates with the second access point 12 to confirm whether or not a wireless terminal other than the first access point 11 exists in the wireless network 10. The synchronization packet is transmitted periodically using a wireless communication channel different from the communication channel. The synchronization packet includes information that the first access point 11 can connect the video / audio device to the wired network.
[0040]
Upon receiving the synchronization packet, the wireless terminals 13 to 15 return a registration request packet to the first access point 11. When the first access point 11 receives the registration request packet transmitted by each wireless terminal, the first access point 11 registers the address and wireless communication channel of each wireless terminal obtained from the registration request packet in the terminal information management table 26. At the same time, a registration request packet of each wireless terminal is transmitted to the second access point 12. When the second access point 12 receives the registration request packet of each wireless terminal transmitted by the first access point 11 via the wireless transmission path 53, the second access point 12 stores an address of each wireless terminal, a wireless communication channel, and the like in a terminal information management table. Register
[0041]
Note that a wireless terminal that does not need to connect to a video / audio device responds to the synchronization packet of the second access point 12 without responding to the synchronization packet of the first access point 11. Is also good. Whether or not the access point is connected to a video / audio device is determined by the wireless terminal based on information included in the synchronization packet.
[0042]
Next, an operation will be described in which the set-top box 16 serving as a video / audio device receives streaming distribution of video content received from the broadcast receiving antenna 51 and simultaneously accesses the Internet mainly by the wireless terminal 13.
[0043]
(1) First, a method for receiving streaming distribution of video content from the set-top box 16 will be described. The wireless terminal 13 inquires of the first access point 11 about the address of the device having the set-top box function. The first access point 11 returns the address of the set top box 16 held in the terminal information management table 26 to the wireless terminal 13. The wireless terminal 13 enters the address of the first access point 11 in the relay source address, designates the address of the set top box 16 as the destination address, designates the video content, and makes a content distribution request. Here, the method of managing and specifying the video content is not specified.
[0044]
When receiving the packet addressed to the set-top box 16 from the wireless terminal 13, the first access point 11 searches the terminal information management table 26 for the address of the set-top box 16. When the address of the set-top box 16 is confirmed, the bridge unit 28 converts the address into the address format and the packet format defined by the protocol on the wired side, and outputs the format to the wired side via the wired protocol control unit 29 and the wired communication unit 30.
[0045]
When receiving the content distribution request packet from the first access point 11, the set top box 16 transmits the specified video content in the MPEG2 transport stream format. When the first access point 11 receives the video content, the first access point 11 converts the video content into a format of a wireless packet by the bridge unit 28. Here, the destination address of the wireless packet is the address of the wireless terminal 13, the relay source address is the address of the first access point 11, and the source address is the virtual address of the set-top box 16 registered in the terminal information management table 26. The address is inserted, and the MPEG2 transport stream of the video content is inserted into the payload. When the routing unit 25 recognizes that the wireless packet is addressed to the wireless terminal 13, the wireless packet is sent to the first wireless control unit 22 and transmitted from the antenna 21 a to the wireless terminal 13 via the first wireless communication unit 21. I do.
[0046]
At this time, a method of transmitting the MPEG2 transport stream will be described with reference to FIG. FIG. 4 shows a frame configuration when transmitting and receiving a packet between the first access point 11 and each wireless terminal. The first access point 11 periodically transmits a synchronization packet in frame synchronization, and subsequently allocates a time slot for transmitting isochronous data such as an MPEG2 transport stream. This time slot secures a band necessary for transmitting the MPEG2 transport stream according to the content such as video content.
[0047]
The time slot specifies which time slot and how long a predetermined video content addressed to a predetermined terminal is used in a synchronization packet. For example, when the video content requested by the wireless terminal 13 requires a bandwidth of 6 Mbps, a bandwidth obtained by adding redundancy of a header portion to 6 Mbps is allocated to the slot 1. The first access point 11 transmits the MPEG2 transport stream transmitted from the set top box 16 to the wireless terminal 13 at the time timing of slot 1.
[0048]
Although slots 1 to 3 are allocated in FIG. 4, transmission and reception of control packets such as registration request packets and data packets such as Internet data between the first access point 11 and the wireless terminal are performed during the remaining time of the frame period. Used for
[0049]
When receiving the wireless packet transmitted by the first access point 11, the wireless terminal 13 extracts the MPEG2 transport stream from the payload. The wireless terminal 13 has a built-in MPEG2 decoder or is provided externally, decodes the extracted MPEG2 transport stream, and displays video contents on a display.
[0050]
(2) Next, a method in which the wireless terminal 13 accesses the Internet will be described. When a packet is transmitted from the wireless terminal 13 to the Internet, the address of the access destination is entered in the destination address, the address of the wireless terminal 13 is entered in the source address, and the address of the first access point 11 is entered in the relay destination address. Is transmitted using a wireless communication channel communicating with the access point 11. The first access point 11 receives a packet from the wireless terminal 13 via the antenna 21a of the first wireless communication unit 21 and sends the packet to the first wireless control unit 22. The routing means 25 searches the terminal information management table 26 for the destination address of the received packet. Since the destination address of the Internet is not registered in the terminal information management table 26, it is determined that there is no packet transmission destination in the network with which the first access point 11 can communicate. The address of the second access point 12 is inserted into the relay source address, the address of the first access point 11 is sent to the second wireless control means 24, and the second access point is transmitted from the antenna 23a of the second wireless communication means 23. 12 is transmitted.
[0051]
When receiving the packet transmitted by the first access point 11 via the wireless transmission path 53, the second access point 12 similarly confirms that there is no destination address of the packet in the terminal information management table, and The packet is transferred to the bridge modem 18 and transmitted to the Internet via the public network 52.
[0052]
Conversely, a packet addressed to the wireless terminal 13 from the Internet network is sent to the second access point 12 via the public network 52 and the bridge modem 18. The second access point 12 confirms that the address of the wireless terminal 13 is present in the terminal information management table, and transmits a packet to the wireless terminal 13. Since the wireless terminal 13 is communicating with the first access point 11 on another wireless communication channel than the one transmitted by the second access point 12, the wireless terminal 13 cannot receive this packet. When the first access point 11 receives a packet transmitted from the second access point 12 to the wireless terminal 13 via the wireless transmission path 53 and the antenna 23a of the second wireless communication unit 23, the first access point 11 performs the second wireless control. It sends to the routing means 25 via the means 24. The routing means 25 searches the terminal information management table 26 for the destination address of the received packet. When it is confirmed that the destination address is registered in the terminal information management table 26, the address of the first access point 11 is entered in the relay source address, sent to the first wireless control unit 22, and sent to the first wireless communication unit 21. From the antenna 21a to the wireless terminal 3.
[0053]
With the above operation, the wireless terminal 13 can relay the first access point 11 and access the Internet via the second access point 12.
[0054]
【The invention's effect】
As described above, according to the present invention, by connecting a plurality of access points with a wireless communication channel different from that between wireless terminals, a plurality of access points can be simultaneously connected from a single wireless terminal without connecting the access points with a wired cable. A remarkable effect is obtained in that a wired network can be accessed, and the Internet can be accessed via a public network while receiving contents from video / audio equipment. In addition, the wireless terminal may be a single wireless communication means, and an existing access point connected to a public network may be used as it is, and a wireless terminal for configuring a wireless network may be used. Costs can be significantly reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a wireless communication system according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of an access point control device forming a first access point of the wireless communication system according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a format of a wireless communication packet of the wireless communication system according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a configuration of a wireless communication frame of the wireless communication system according to the embodiment of the present invention.
FIG. 5 is a block diagram showing a configuration of a wireless communication system according to a conventional technique.
[Explanation of symbols]
10. Wireless network
11 First access point connected to video / audio equipment
12. Second access point connected to public network
13-15 wireless terminal
16 Set Top Box
17 Digital Video
18 bridge modem
20 Access point control device
21 First wireless communication means
21a, 23a antenna
22. First wireless control means
23 Second wireless communication means
24 Second wireless control means
25 Routing means
26 Terminal information management table
27 Wireless protocol control means
28 Bridge means
29 Wired protocol control means
30 Wired communication means
40 packets
44 Destination address
45 Relay address
46 Relay source address
47 Source address
51 Broadcast receiving antenna
52 public network
53 Wireless transmission path

Claims (6)

Including a first access point connected to a video / audio device that receives or stores image / audio information, a second access point connected to a public network via a gateway, and at least one wireless terminal In wireless networks,
The first access point wirelessly communicates information from the video / audio device to the wireless terminal in a packet format in accordance with an access request to the video / audio device from the wireless terminal, and transmits the information from the wireless terminal. Configured to relay communication between the wireless terminal and the second access point by packet-type wireless communication according to an access request to the public network,
A wireless transmission path between the first access point and the second access point has a communication channel different from a communication channel of a wireless transmission path between the first access point and the wireless terminal. Wireless communication system set to. The wireless communication method between the first access point and the second access point is the same as the wireless communication method between the first access point and the wireless terminal. The wireless communication system according to claim 1, wherein The format of a packet on a wireless transmission path between the first access point and the second access point is common to a packet on a wireless transmission path between the first access point and the wireless terminal, The wireless communication system according to claim 2, wherein the header has a destination address, a relay destination address, a relay source address, and a source address. A wired interface for connecting video / audio equipment that receives or stores image / audio information,
First wireless communication means for wirelessly communicating with the wireless terminal using the first wireless communication channel;
Second wireless communication means for wirelessly communicating with an access point connected to a public network through a gateway using a second wireless communication channel;
An access point control device, comprising: a wireless protocol control unit that performs routing of packets transmitted and received between the first wireless communication unit and the second wireless communication unit. 5. The access point control device according to claim 4, wherein said first and second wireless communication means have a modulation method of OFDM. The access point control device according to claim 4 or 5, wherein the wired interface is IEEE1394.

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