Wireless communication system and method of conducting wireless communication Number:7,177,292 from the United States Patent and Trademark Office (PTO) owispatent

Title: Wireless communication system and method of conducting wireless communication

Abstract: A wireless communication system includes a plurality of base stations, a mobile wireless communication device which makes wireless communication with the base stations, a terminal device, and a router through which the base stations make communication with an IP network. The terminal device transmits an address thereof to the mobile wireless communication device, before the mobile wireless communication device makes link with one of the base stations. The terminal device fabricates a frame addressed to an address of the router, and transmits the frame to the router, after the mobile wireless communication device has made link with one of the base stations. The router transmits an address thereof to the base stations, before the mobile wireless communication device makes link with one of the base stations. The router fabricates a frame addressed to an address of the terminal device, and transmits the frame to the terminal device, after the mobile wireless communication device has made link with one of the base stations.

Patent Number: 7,177,292 Issued on 02/13/2007 to Mizukoshi

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Inventors:	Mizukoshi; Yasuhiro (Tokyo, JP)
Assignee:	NEC Corporation (Tokyo, JP)
Appl. No.:	09/984,129
Filed:	October 29, 2001

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Foreign Application Priority Data

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Oct 27, 2000 [JP]			2000-328847

Current U.S. Class:	370/331 ; 370/401
Current International Class:	H04Q 7/00 (20060101)
Field of Search:	370/338,469 455/435

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References Cited [Referenced By]

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U.S. Patent Documents

	4991171		February 1991		Teraslinna et al.
	6163532		December 2000		Taguchi et al.
	6230012		May 2001		Willkie et al.
	6424639		July 2002		Lioy et al.
	6665537		December 2003		Lioy
	6763012		July 2004		Lord et al.
	6775553		August 2004		Lioy
	6959009		October 2005		Asokan et al.

Foreign Patent Documents

	0 828 398		Mar., 1998		EP
	0 917 328		May., 1999		EP
	A 9-275399		Oct., 1997		JP
	A 10-145369		May., 1998		JP
	A 2000-4468		Jan., 2000		JP
	A 2000-92562		Mar., 2000		JP
	A 2001-345829		Dec., 2001		JP
	WO 00/08822		Feb., 2000		WO
	WO 00/18066		Mar., 2000		WO
	WO 00/51312		Aug., 2000		WO
	WO 00/76173		Dec., 2000		WO

Primary Examiner: Nguyen; Chau
Assistant Examiner: Grey; Christopher
Attorney, Agent or Firm: Young & Thompson

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Claims

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What is claimed is:

1. A wireless communication system comprising: (a) a plurality of base stations each having a wireless communication device; (b) at least one mobile wireless communication device which makes wireless communication with said base stations; (c) at least one terminal device transmitting IP packets to and receiving IP packets from said mobile wireless communication device; and (d) a router through which said base stations make communication with an IP network, wherein said terminal device transmits an address thereof to said mobile wireless communication device, before said mobile wireless communication device makes link with one of said base stations, said terminal device fabricates a frame addressed to an address of said router having been received through said mobile wireless communication device, and transmits the thus fabricated frame to said router through both said mobile wireless communication device and said one of said base stations, after said mobile wireless communication device has made link with one of said base stations, said router transmits an address thereof to said base stations, before said mobile wireless communication device makes link with one of said base stations, said router fabricates a frame addressed to an address of said terminal device having been received through said one of said base stations, and transmits the thus fabricated frame to said terminal device through both said mobile wireless communication device and said one of said base stations, after said mobile wireless communication device has made link with one of said base stations.

2. The wireless communication system as set forth in claim 1, wherein, said router makes wireless communication with each of said base stations through an Ethernet, and said mobile wireless communication device makes wireless communication with said terminal device through an Ethernet, each base station is comprised of an interface which includes a wireless communication equipment through which the base station makes wireless communication with the wireless communication device, a message transceiver which transmits messages to and receives messages from each of nodes which are connected to the IP network, and a memory which stores an Ethernet MAC address of the router and data indicative of locations of the base stations, as base station data (RSU data), and further stores the Ethernet MAC address of the terminal device and a message transmitted from the wireless communication device that the terminal device has moved away, as a wireless communication device list (OBE list).

3. The wireless communication system as set forth in claim 1, wherein said base stations and said router defines a non-mobile network system, and said mobile wireless communication device and said terminal device defines a mobile network system.

4. The wireless communication system as set forth in claim 3, wherein said mobile network system is mounted in an automobile.

5. The wireless communication system as set forth in claim 1, wherein said wireless communication system includes a plurality of said terminal devices, and further comprising a second router through which said mobile wireless communication device makes IP communication with said terminal devices.

6. A wireless communication system comprising: (a) a plurality of base stations each having a wireless communication device; (b) at least one mobile wireless communication device which makes wireless communication with said base stations; (c) at least one terminal device transmitting IP packets to and receiving IP packets from said mobile wireless communication device; and (d) a router through which said base stations make communication with an IP network, wherein said terminal device informs said mobile wireless communication device that said terminal device has moved away, before said mobile wireless communication device makes link with one of said base stations, said mobile wireless communication device informs said one of said base stations that said terminal device has moved away, when said mobile wireless communication device makes link with said one of said base stations, said one of said base stations informs said router that said terminal device has moved away, after said mobile wireless communication device has made link with said one of said base stations.

7. The wireless communication system as set forth in claim 6, wherein said router makes wireless communication with each of said base stations through an Ethernet, and said mobile wireless communication device makes wireless communication with said terminal device through an Ethernet.

8. The wireless communication system as set forth in claim 6, wherein said base stations and said router defines a nonmobile network system, and said mobile wireless communication device and said terminal device defines a mobile network system.

9. The wireless communication system as set forth in claim 8, wherein said mobile network system is mounted in an automobile.

10. The wireless communication system as set forth in claim 6, wherein said wireless communication system includes a plurality of said terminal devices, and further comprising a second router through which said mobile wireless communication device makes IP communication with said terminal devices.

11. A wireless communication system comprising: (a) a plurality of base stations each having a wireless communication device; (b) at least one mobile wireless communication device which makes wireless communication with said base stations; (c) at least one terminal device transmitting IP packets to and receiving IP packets from said mobile wireless communication device; and (d) a router through which said base stations make communication with an IP network, wherein said terminal device transmits an address of said terminal device to said mobile wireless communication device, before said mobile wireless communication device makes link with one of said base stations, said mobile wireless communication device transmits an address of said terminal device to said one of said base stations, when said mobile wireless communication device makes link with said one of said base stations, said one of said base stations transmits an address of said terminal device to a base station or base stations to which said router makes communication with.

12. The wireless communication system as set forth in claim 11, wherein said router makes wireless communication with each of said base stations through an Ethernet, and said mobile wireless communication device makes wireless communication with said terminal device through an Ethernet.

13. The wireless communication system as set forth in claim 11, wherein said base stations and said router defines a non-mobile network system, and said mobile wireless communication device and said terminal device defines a mobile network system.

14. The wireless communication system as set forth in claim 13, wherein said mobile network system is mounted in an automobile.

15. The wireless communication system as set forth in claim 11, wherein said wireless communication system includes a plurality of said terminal devices, and further comprising a second router through which said mobile wireless communication device makes IP communication with said terminal devices.

16. A wireless communication system comprising: (a) a plurality of base stations each having a wireless communication device; (b) at least one mobile wireless communication device which makes wireless communication with said base stations; (c) at least one terminal device transmitting IP packets to and receiving IP packets from said mobile wireless communication device; and (d) a router through which said base stations make communication with an IP network, wherein each of said base stations, on receipt of a broadcast packet, judges whether an address of a transmitter of said broadcast packet is an address of said router, and transmits said broadcast packet to said mobile wireless communication device with which said each of said base stations has made link, if said address of a transmitter of said broadcast packet is an address of said router.

17. The wireless communication system as set forth in claim 16, wherein each of said base stations transmits said broadcast packet only to said router, if said address of a transmitter of said broadcast packet is not an address of said router.

18. The wireless communication system as set forth in claim 16, wherein said router makes wireless communication with each of said base stations through an Ethernet, and said mobile wireless communication device makes wireless communication with said terminal device through an Ethernet.

19. The wireless communication system as set forth in claim 16, wherein said base stations and said router defines a non-mobile network system, and said mobile wireless communication device and said terminal device defines a mobile network system.

20. The wireless communication system as set forth in claim 19, wherein said mobile network system is mounted in an automobile.

21. The wireless communication system as set forth in claim 16, wherein said wireless communication system includes a plurality of said terminal devices, and further comprising a second router through which said mobile wireless communication device makes IP communication with said terminal devices.

22. A method of conducting wireless communication in a wireless communication system comprising: (a) a plurality of base stations each having a wireless communication device; (b) at least one mobile wireless communication device which makes wireless communication with said base stations; c) at least one terminal device transmitting IP packets to and receiving IP packets from said mobile wireless communication device; and (d) a router through which said base stations make communication with an IP network, said method comprising the steps of: (a) transmitting an address of said terminal device to said mobile wireless communication device from said terminal device, and transmitting an address of said router to one of said base stations from said router, before said mobile wireless communication device makes link with said one of said base stations; (b) said terminal device fabricating a frame addressed to an address of said router having been received through said mobile wireless communication device, and transmitting the thus fabricated frame to said router through both said mobile wireless communication device and said one of said base stations, after said mobile wireless communication device has made link with one of said base stations; and c) said router fabricating a frame addressed to an address of said terminal device having been received through said one of said base stations, and transmitting the thus fabricated frame to said terminal device through both said mobile wireless communication device and said one of said base stations, after said mobile wireless communication device has made link with one of said base stations.

23. A method of conducting wireless communication in a wireless communication system comprising: a) a plurality of base stations each having a wireless communication device; (b) at least one mobile wireless communication device which makes wireless communication with said base stations; (c) at least one terminal device transmitting IP packets to and receiving IP packets from said mobile wireless communication device; and (d) a router through which said base stations make communication with an IP network, said method comprising the steps of: (a) said terminal device informing said mobile wireless communication device that said terminal device has moved away, before said mobile wireless communication device makes link with one of said base stations; (b) said mobile wireless communication device informing said one of said base stations that said terminal device has moved away, when said mobile wireless communication device makes link with said one of said base stations; (c) said one of said base stations informing said router that said terminal device has moved away, after said mobile wireless communication device has made link with said one of said base stations.

24. A method of conducting wireless communication in a wireless communication system comprising: (a) a plurality of base stations each having a wireless communication device; (b) at least one mobile wireless communication device which makes wireless communication with said base stations; c) at least one terminal device transmitting IP packets to and receiving IP packets from said mobile wireless communication device; and (d) a router through which said base stations make communication with an IP network, said method comprising the steps of: (a) said terminal device transmitting an address thereof to said mobile wireless communication device, before said mobile wireless communication device makes link with one of said base stations; (b) said mobile wireless communication device transmitting an address of said terminal device to said one of said base stations, when said mobile wireless communication device makes link with said one of said base stations; and (c) said one of said base stations transmitting an address of said terminal device to a base station or base stations to which said router makes communication with.

25. A method of conducting wireless communication in a wireless communication system comprising: (a) a plurality of base stations each having a wireless communication device; (b) at least one mobile wireless communication device which makes wireless communication with said base stations; (c) at least one terminal device transmitting TB packets to and receiving TB packets from said mobile wireless communication device; and (d) a router through which said base stations make communication with an IP network, said method comprising the steps of: (a) each of said base stations, on receipt of a broadcast packet, judging whether an address of a transmitter of said broadcast packet is an address of said router; and (b) said one of said base stations transmitting said broadcast packet to said mobile wireless communication device with which said each of said base stations has made link, if said address of a transmitter of said broadcast packet is an address of said router.

26. The method as set forth in claim 25, further comprising the step of each of said base stations transmitting said broadcast packet only to said router, if said address of a transmitter of said broadcast packet is not an address of said router.

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Description

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a wireless communication system and a method of conducting wireless communication both of which allow a terminal device to make IP communication.

2. Description of the Related Art

As Internet has been widely utilized, there is a need to a communication system in which for instance, a terminal device mounted in an automobile can readily makes access to Internet.

Conventionally, in order to cause a terminal device mounted in an automobile to make access to Internet the terminal device had to be connected to a cellular phone to make access to a router or a server (an access point) through which the cellular phone can make access to Internet through a cellular phone network.

However, the above-mentioned conventional way in which a terminal device makes access to an access point through a cellular phone network is not suitable for long time use, because a communication fee is unavoidably expensive.

If a user were driving an automobile, he/she would like to receive information about road traffic and/or navigation for arriving at his/her destination.

As a system for allowing a terminal device mounted in an automobile to make wireless communication therewith, a wireless system between a road and an automobile is presently developed. An example of such a wireless system is a system for automatically charging an automobile for a toll road fee. In the wireless system between a road and an automobile, a wireless communication device is mounted in an automobile, and a base station which can make wireless communication within a relatively narrow area is located around a tollbooth for transmitting information about a fee to automobile drivers. The wireless system is expected to further provide automobile drivers with various services including traffic information, by increasing the number of base stations.

However, since the above-mentioned wireless system is originally developed for the system for automatically charging an automobile for a toll road fee, the wireless system is designed not to have a network layer. Accordingly, the above-mentioned wireless system is accompanied with a problem that it is quite difficult or almost impossible to successively transmit IP packets to a terminal device now moving, from a plurality of base stations.

For instance, Japanese Unexamined Patent Publication No. 2000-4468 has suggested a wireless communication system in which a road and an automobile make interactive wireless communication with each other. The automobile has a wireless communication device for making wireless communication with the road. The road includes first means for detecting an automobile entering a service area covered with a plurality of micro-cells, and transmitting a detection signal, second means for receiving the detection signal and transmitting a first signal indicative of where the automobile is, a plurality of base stations each of which makes wireless communication with the wireless communication device and is associated with each of the micro-cells, and a controller which produces registration data of the automobile, based on the detection signal, transmits the registration data to the wireless communication device through the first means, and controls the base stations by switching the micro-cells, based on the first signal and the registration data.

The above-mentioned problem remains unsolved even in the above-mentioned Publication.

SUMMARY OF THE INVENTION

In view of the above-mentioned problem in the conventional wireless communication system, it is an object of the present invention to provide a wireless communication system which is capable of providing various services including Internet service, with a user such as an automobile driver.

In one aspect of the present invention, there is provided a wireless communication system including (a) a plurality of base stations each having a wireless communication device, (b) at least one mobile wireless communication device which makes wireless communication with the base stations, (c) at least one terminal device transmitting IP packets to and receiving IP packets from the mobile wireless communication device, and (d) a router through which the base stations make communication with an IP network, wherein the terminal device transmits an address thereof to the mobile wireless communication device, before the mobile wireless communication device makes link with one of the base stations, the terminal device fabricates a frame addressed to an address of the router having been received through the mobile wireless communication device, and transmits the thus fabricated frame to the router through both the mobile wireless communication device and the one of the base stations, after the mobile wireless communication device has made link with one of the base stations, the router transmits an address thereof to the base stations, before the mobile wireless communication device makes link with one of the base stations, the router fabricates a frame addressed to an address of the terminal device having been received through the one of the base stations, and transmits the thus fabricated frame to the terminal device through both the mobile wireless communication device and the one of the base stations, after the mobile wireless communication device has made link with one of the base stations.

It is preferable that the router makes wireless communication with each of the base stations through an Ethernet, and the mobile wireless communication device makes wireless communication with the terminal device through an Ethernet.

For instance, the base stations and the router defines a non-mobile network system, and the mobile wireless communication device and the terminal device defines a mobile network system.

For instance the mobile network system is mounted in an automobile.

For instance, the wireless communication system may include a plurality of the terminal devices, and further include a second router through which the mobile wireless communication device makes IP communication with the terminal devices.

There is further provided a wireless communication system including (a) a plurality of base stations each having a wireless communication device, (b) at least one mobile wireless communication device which makes wireless communication with the base stations, (c) at least one terminal device transmitting IP packets to and receiving IP packets from the mobile wireless communication device, and (d) a router through which the base stations make communication with an IP network, wherein the terminal device informs the mobile wireless communication device that the terminal device has moved away, before the mobile wireless communication device makes link with one of the base stations, the mobile wireless communication device informs the one of the base stations that the terminal device has moved away, when the mobile wireless communication device makes link with the one of the base stations, the one of the base stations informs the router that the terminal device has moved away, after the mobile wireless communication device has made link with the one of the base stations.

There is still further provided a wireless communication system including (a) a plurality of base stations each having a wireless communication device, (b) at least one mobile wireless communication device which makes wireless communication with the base stations, (c) at least one terminal device transmitting IP packets to and receiving IP packets from the mobile wireless communication device, and (d) a router through which the base stations make communication with an IP network, wherein the terminal device transmits an address of the terminal device to the mobile wireless communication device, before the mobile wireless communication device makes link with one of the base stations, the mobile wireless communication device transmits an address of the terminal device to the one of the base stations, when the mobile wireless communication device makes link with the one of the base stations, the one of the base stations transmits an address of the terminal device to a base station or base stations to which the router makes communication with.

There is yet further provided a wireless communication system including (a) a plurality of base stations each having a wireless communication device, (b) at least one mobile wireless communication device which makes wireless communication with the base stations, (c) at least one terminal device transmitting IP packets to and receiving IP packets from the mobile wireless communication device, and (d) a router through which the base stations make communication with an IP network, wherein each of the base stations, on receipt of a broadcast packet, judges whether an address of a transmitter of the broadcast packet is an address of the router, and transmits the broadcast packet to the mobile wireless communication device with which the each of the base stations has made link, if the address of a transmitter of the broadcast packet is an address of the router.

It is preferable each of the base stations transmits the broadcast packet only to the router, if the address of a transmitter of the broadcast packet is not an address of the router.

In another aspect of the present invention, there is provided a method of conducting wireless communication in a wireless communication system including (a) a plurality of base stations each having a wireless communication device, (b) at least one mobile wireless communication device which makes wireless communication with the base stations, (c) at least one terminal device transmitting IP packets to and receiving IP packets from the mobile wireless communication device, and (d) a router through which the base stations make communication with an IP network, the method including the steps of (a) transmitting an address of the terminal device to the mobile wireless communication device from the terminal device, and transmitting an address of the router to one of the base stations from the router, before the mobile wireless communication device makes link with the one of the base stations, (b) the terminal device fabricating a frame addressed to an address of the router having been received through the mobile wireless communication device, and transmitting the thus fabricated frame to the router through both the mobile wireless communication device and the one of the base stations, after the mobile wireless communication device has made link with one of the base stations, and (c) the router fabricating a frame addressed to an address of the terminal device having been received through the one of the base stations, and transmitting the thus fabricated frame to the terminal device through both the mobile wireless communication device and the one of the base stations, after the mobile wireless communication device has made link with one of the base stations.

There is further provided a method of conducting wireless communication in a wireless communication system including (a) a plurality of base stations each having a wireless communication device, (b) at least one mobile wireless communication device which makes wireless communication with the base stations, (c) at least one terminal device transmitting IP packets to and receiving IP packets from the mobile wireless communication device, and (d) a router through which the base stations make communication with an IP network, the method including the steps of (a) the terminal device informing the mobile wireless communication device that the terminal device has moved away, before the mobile wireless communication device makes link with one of the base stations, (b) the mobile wireless communication device informing the one of the base stations that the terminal device has moved away, when the mobile wireless communication device makes link with the one of the base stations, (c) the one of the base stations informing the router that the terminal device has moved away, after the mobile wireless communication device has made link with the one of the base stations.

There is still further provided a method of conducting wireless communication in a wireless communication system including (a) a plurality of base stations each having a wireless communication device, (b) at least one mobile wireless communication device which makes wireless communication with the base stations, (c) at least one terminal device transmitting IP packets to and receiving IP packets from the mobile wireless communication device, and (d) a router through which the base stations make communication with an IP network, the method including the steps of (a) the terminal device transmitting an address thereof to the mobile wireless communication device, before the mobile wireless communication device makes link with one of the base stations, (b) the mobile wireless communication device transmitting an address of the terminal device to the one of the base stations, when the mobile wireless communication device makes link with the one of the base stations, and (c) the one of the base stations transmitting an address of the terminal device to a base station or base stations to which the router makes communication with.

There is yet further provided a method of conducting wireless communication in a wireless communication system including (a) a plurality of base stations each having a wireless communication device, (b) at least one mobile wireless communication device which makes wireless communication with the base stations, (c) at least one terminal device transmitting IP packets to and receiving IP packets from the mobile wireless communication device, and (d) a router through which the base stations make communication with an IP network, the method including the steps of (a) each of the base stations, on receipt of a broadcast packet, judging whether an address of a transmitter of the broadcast packet is an address of the router, and (b) the one of the base stations transmitting the broadcast packet to the mobile wireless communication device with which the each of the base stations has made link, if the address of a transmitter of the broadcast packet is an address of the router.

The method may further include the step of each of the base stations transmitting the broadcast packet only to the router, if the address of a transmitter of the broadcast packet is not an address of the router.

In still another aspect of the present invention, there is provided a router through which each of base stations each having a mobile wireless communication device makes wireless communication with an IP network, including (a) a first controller which transmits data including an address of the router, to the base stations, (b) a second controller which includes a routing table in which data about routes in which IP packets are transmitted to a mobile terminal device is stored, and determines destination to which IP packets are to be transmitted, and (c) a third controller which updates the routing table in accordance with data indicating that the mobile terminal device has moved away, transmitted from the mobile terminal device.

In yet another aspect of the present invention, there is provided a wireless base station which makes wireless communication with a mobile wireless communication device, including (a) an interface through which the wireless base station makes wireless communication with the mobile wireless communication device, (b) a message transceiver which transmits messages to and receives messages from a router and base stations making communication with the router, and (c) a memory which stores an address of the router, an address of a terminal device making communication with the mobile wireless communication device, and a message indicating that the terminal device has moved away.

It is preferable that the message transceiver transmits the message to the router on behalf of the terminal device, when a link between the wireless base station and the mobile wireless communication device has been established.

It is preferable that the message transceiver, on receipt of an address of the terminal device, transmits an address of the terminal device to a base station or base stations with which the router makes communication.

It is preferable that the message transceiver, on receipt of a broadcast packet, judges whether an address of a transmitter of the broadcast packet is an address of the router, and transmits the broadcast packet to the mobile wireless communication device with which the wireless base station has made link, if the address of a transmitter of the broadcast packet is an address of the router.

It is preferable that the message transceiver transmits the broadcast packet only to the router, if the address of a transmitter of the broadcast packet is not an address of the router.

In still yet another aspect of the present invention, there is provided a mobile wireless communication device capable of making wireless communication with a base station, including (a) an interface through which the mobile wireless communication device makes wireless communication with the base station, (b) a message transceiver which transmits messages to and receives messages from a terminal device which can make wireless communication with the mobile wireless communication device, and (c) a memory which stores an address of the terminal device, an address of a router, and data indicating where each of base stations is.

In still further another aspect of the present invention, there is provided a terminal device transmitting IP packets to and receiving IP packets from a mobile wireless communication device, including (a) a controller which transmits an address of the terminal device to the mobile wireless communication device, and (b) a message transceiver which transmits a message indicating that the terminal device has moved away, to the mobile wireless communication device.

The advantages obtained by the aforementioned present invention will be described hereinbelow.

In the wireless communication system, the terminal device transmits its address to the mobile wireless communication device, and the router transmits its address to the base stations, before the mobile wireless communication device makes link with one of the base stations. Once the link has been established, the terminal device fabricates a frame addressed to an address of the router having been received through the mobile wireless communication device, and transmits the thus fabricated frame to the router through both the mobile wireless communication device and the base station. Thus, the terminal device can make IP communication with others through a wireless communication system such as the above-mentioned wireless communication system between a road and an automobile. Even if the terminal device moves away and switches a base station through which the terminal device makes wireless communication, the terminal device can continue making wireless communication.

In the wireless communication system, the terminal device informs the mobile wireless communication device that the terminal device has moved away, before the mobile wireless communication device makes link with one of the base stations. The mobile wireless communication device informs the one of the base stations that the terminal device has moved away, when the mobile wireless communication device makes link with the one of the base stations. The one of the base stations informs the router on behalf of the terminal device that the terminal device has moved away, after the mobile wireless communication device has made link with the one of the base stations. The router can shorten time required to deal with the information that the terminal device has moved away. In addition, it is no longer necessary for the terminal device to inform the router that the terminal device has moved away, ensuring that it is no longer necessary for the mobile wireless communication device and the base stations to transmit such information therethrough.

In the wireless communication system, the terminal device transmits its address to the mobile wireless communication device, before the mobile wireless communication device makes link with one of the base stations, and the mobile wireless communication device transmits an address of the terminal device to the one of the base stations, when the mobile wireless communication device makes link with the one of the base stations. The one of the base stations which has received an address of the terminal device transmits an address of the terminal device to a base station or base stations to which the router makes communication with. Accordingly, the base station which has first made link with the mobile wireless communication device can be aware of that the terminal device has moved away, and consequently, is no longer necessary to transmit frames to the terminal device, even if the base station receives a framed addressed to the terminal device. Hence, it is possible to avoid wasteful IP packets from being transmitted through the wireless communication system.

In the wireless communication system, each of the base stations, on receipt of a broadcast packet, judges whether an address of a transmitter of the broadcast packet is an address of the router. The each of the base stations transmits the broadcast packet to the mobile wireless communication device with which the each of the base stations has made link, if the address of a transmitter of the broadcast packet is an address of the router, whereas the each of the base stations transmits the broadcast packet only to the router, if the address of a transmitter of the broadcast packet is not an address of the router. Hence, since the broadcast packets having been transmitted from the terminal device are not transmitted to other terminal devices, it would be possible to avoid wasteful wireless communication.

The above and other objects and advantageous features of the present invention will be made apparent from the following description made with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the wireless communication system in accordance with a preferred embodiment of the present invention.

FIG. 2 is a block diagram of the router, the base station, the wireless communication device, and the terminal device all constituting the wireless communication system illustrated in FIG. 1.

FIG. 3 shows an example of a format of a frame used in the wireless communication system.

FIG. 4 shows an example of a format of the Message Payload field illustrated in FIG. 3.

FIG. 5 shows an example of a format of a frame indicating that the terminal device has moved away which frame is to be transmitted to the router from the base station on behalf of the terminal device.

FIG. 6 is a sequence chart showing an operation of the wireless communication system.

FIG. 7 is a sequence chart showing an operation of transmitting a frame indicating that the terminal device has moved away, to the router from the base station.

FIG. 8 is a sequence chart showing an operation to be carried out when the terminal device makes wireless communication with the router through a plurality of base stations.

FIG. 9 is a sequence chart showing an operation to be carried out when a plurality of the automobile networks makes wireless communication with the router through the base station.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a block diagram of the wireless communication system in accordance with an embodiment of the present invention, and FIG. 2 is a block diagram of the router, the base station, the wireless communication device, and the terminal device all constituting the wireless communication system illustrated in FIG. 1.

As illustrated in FIG. 1, the wireless communication system is comprised of a plurality of road networks 1 each including a wireless communication equipment equipped around a road or in a tollbooth, and a plurality of automobile networks 2 each mounted in an automobile cruising on the road.

Each of the road networks 1 is comprised of a plurality of base stations (illustrated as "RSU" in FIG. 1) 12 each including a wireless communication device, and a router 11 through which the base stations 12 make IP communication with an IP network 3.

Each of the automobile networks 2 is comprised of a wireless communication device 21 (illustrated as "OBE" in FIG. 1) mounted in an automobile for making wireless communication with the base stations 12, and a terminal device 22 or an IP node mounted in an automobile for transmitting IP packets to and receiving IP packets from the wireless communication device 21.

Each of the automobile networks 2 may be designed to include a plurality of the terminal devices 22, in which case, each of the automobile networks 2 may be designed to include a router through which the wireless communication device 21 makes IP communication with the terminal devices 22.

In the wireless communication system, the router 11 and the base stations 12 make communication with each other through Ethernet, and the wireless communication device 21 and the terminal device 22 makes communication with each other through Ethernet. In addition, the base station 12 and the wireless communication device 21 transmit frames to each other through Ethernet.

The above-mentioned wireless communication system between a road and an automobile is comprised of the wireless communication device 21 and the base station 12, in which equipments necessary for charging automobile drivers for a toll road fee are connected to the base station 12. Accordingly, the wireless communication system illustrated in FIG. 1 has a structure where the terminal device 22 is designed to make communication with the wireless communication device 21 used for the above-mentioned wireless communication system between a road and an automobile, and the base stations 12 and the router 11 are designed to make communication with each other through Ethernet to thereby allow the base stations 12 to make access to the IP network 3.

As illustrated in FIG. 2, the router 11 is comprised of a first controller 111 determining an addressee to which IP packets are to be transmitted, and including a routing table storing therein data about routes through which IP packets are transmitted, a second controller 112 which updates the routing table in accordance with a message transmitted from the terminal device 22 indicating that the terminal device 22 has moved away, and a third controller 113 transmitted certain data to the associated base stations 12.

Each of the base stations 12 is comprised of an interface 121 which includes a wireless communication equipment through which the base station 12 makes wireless communication with the wireless communication device 21, a message transceiver 122 which transmits messages to and receives messages from each of nodes which are connected to the road network 1, and a memory 123 which stores Ethernet MAC address of the router 11 and data indicative of locations of the base stations 12, as base station data (RSU data), and further stores Ethernet MAC address of the terminal device 22 and a message transmitted from the wireless communication device 21 that the terminal device 22 has moved away, as a wireless communication device list (OBE list).

The wireless communication device 21 is comprised of an interface 211 which includes a wireless communication equipment through which the wireless communication device 21 makes wireless communication with the base stations 12, a memory 212 which stores Ethernet MAC address of the terminal device 22 and a message transmitted from the wireless communication device 21 that the terminal device 22 has moved away, as terminal device data, and further stores Ethernet MAC address of the router 11 and data indicative of locations of the base stations 12, as base station data (RSU data), and a message transceiver 213 which transmits messages to and receives messages from each of nodes of the automobile network 2.

The terminal device 22 or IP node mounted in an automobile is comprised of a TCP/IP processor 221 which produces and takes IP packets into each packets, a controller 222 which produces an Ethernet frame and a particular message, and transmits them to the wireless communication device 21, and a message producer 223 which produces a message that the terminal device 22 has moved away which message is to be transmitted to the router 11.

Hereinbelow is explained a format of the particular frame which is to be transmitted among the router 11, the base stations 12, the wireless communication device 21, and the terminal device 22, with reference to FIG. 3. Herein, the particular frame means a frame including a message for controlling an operation of the router 11, the base stations 12, the wireless communication device 21, and the terminal device 22. Other frames for transmitting other information are produced in accordance with Ethernet specification, and hence, will not be explained below.

Each of the fields shown in FIG. 3 has a content as follows.

"Destination Ethernet Address": This field indicates Ethernet MAC address of an addressee.

"Source Ethernet Address": This field indicates Ethernet MAC address of an addresser.

"Frame Payload Protocol": Numbers of upper-grade protocols and predetermined numbers are inserted into this field.

"Message Type": This field indicates the number indicative of a type of the particular frame. A message to, be inserted into the field "Message Payload" is determined in accordance with the number.

"Reserved": An addresser inserts "0" into this field, and an addressee disregards this field.

"Message Payload": This field stores a message to be transmitted from or received to of the present frame. This field has a length value (TVL) type format as illustrated in FIG. 4.

Each of the fields shown in FIG. 4 has a content as follows.

"Type": Any one of figure among 0 to 255 is inserted into this field.

"Reserved": An addresser inserts "0" into this field, and an addressee disregards this field.

"Length": This field indicates a length in the range of 0 to 65635.

"Value": This field indicates a byte sequence having a length of octet, and is defined for each of "Type".

Messages is selected from the following messages A, B and C.

A. Target MAC Address:

"Type"=a predetermined number (for instance, "0x01")

"Length"=a predetermined number (for instance, "0x0006")

"Value": Ethernet MAC address is stored in this field. This field is used for transmitting Ethernet MAC addresses of the terminal device 22 and the router 11.

B. TSIP Update Message:

"Type"=a predetermined number (for instance, "0x02")

"Length"=variable

"Value": This field store a TSIP (Transport System Internet Protocol) message which the terminal device 22 requests the wireless communication device 21 to transmit on behalf thereof.

C. Base Station Information:

"Type"=a predetermined number (for instance, "0x03")

"Length"=variable

"Value": This field stores data about locations in a network in which the router 11 makes wireless communication with the base stations 12.

Hereinbelow are explained types of the particular frame and the content of the particular frames.

1. First Frame

The terminal device 22 uses this frame to inform the associated wireless communication device 21 of data necessary for the associated wireless communication device 21 to carry out certain steps, when the wireless communication device 21 and the associated base station 12 make wireless communication with each other.

"Destination Ethernet Address": This field indicates Ethernet MAC address of the wireless communication device 21

"Source Ethernet Address": This field indicates Ethernet MAC address of the terminal device 22.

"Frame Payload Protocol": This field indicates a predetermined number (for instance, "0x7137").

"Message Type": This field indicates a predetermined number. For instance, "Message Type" is defined such that the frame does not contain "TSIP Update Message" when "Message Type" is 0x00, and the frame contains "TSIP Update Message" when "Message Type" is 0x01.

"Message Field": This field includes the following messages: Target MAC Address, and TSIP Update Message.

2. Second Frame

The wireless communication device 21 uses this frame to inform the associated terminal device 22 of network information and the like, when the wireless communication device 21 makes communication with one of the base stations 12.

"Destination Ethernet Address": This field indicates Ethernet MAC address of the terminal device 22.

"Source Ethernet Address": This field indicates Ethernet MAC address of the wireless communication device 21.

"Payload Protocol": This field indicates a predetermined number (for instance, "0x7137").

"Message Type": This field indicates a predetermined number For instance, "Message Type" is defined such that the frame did not transmit "TSIP Update Message" when "Message Type" is 0x80, and the frame transmitted "TSIP Update Message" when "Message Type" is 0x81.

"Message Field": This field includes the following messages: Target MAC Address, and Base Station Information.

3. Third Frame

When the wireless communication device 21 makes communication with one of the base stations 12, the wireless communication device 21 uses this frame to inform other base stations 12 of Ethernet MAC address of the terminal device 22 associated with the wireless communication device 21.

"Destination Ethernet Address": This field indicates Broadcast Ethernet Address (ff: ff: ff: ff: ff: ff).

"Source Ethernet Address": This field indicates Ethernet MAC address of the base station 12.

"Payload Protocol": This field indicates a predetermined number (for instance, "0x7137").

"Message Type": This field indicates a predetermined number (for instance, "0x83").

"Message Field": This field includes the following message: Target MAC Address.

4. Fourth Frame

When the wireless communication device 21 makes communication with the base station 12, the router 1 uses this frame to inform the base station 12 of information to be transmitted to the terminal device 22 from the base station 12.

"Destination Ethernet Address": This field indicates Ethernet MAC address of the base station 12.

"Source Ethernet Address": This field indicates Ethernet MAC address of the router 11.

"Payload Protocol": This field indicates a predetermined number (for instance, "0x7137").

"Message Type": This field indicates a predetermined number (for instance, "0x02").

"Message Field": This field includes the following messages: Target MAC Address, and Base Station Information.

5. Fifth Frame

This frame is a broadcast frame used by the router 11 for inquiring which base station 12 the terminal device 22 makes communication to, using Ethernet MAC address of the terminal device 22 as a retrieval key.

"Destination Ethernet Address": This field indicates Broadcast Ethernet Address (ff: ff: ff: ff: ff: ff).

"Source Ethernet Address": This field indicates Ethernet MAC address of the router 11.

"Payload Protocol": This field indicates a predetermined number (for instance, "0x7137").

"Message Type": This field indicates a predetermined number (for instance, "0x04").

"Message Field": This field includes the following message: Target MAC Address.

6. Sixth Frame

The base station 12 transmits this frame in response to the inquiry transmitted from the router 11 using the fifth frame.

"Destination Ethernet Address": This field indicates Ethernet MAC address of the router 11.

"Source Ethernet Address": This field indicates Ethernet MAC address of the base station 12 making a response.

"Payload Protocol": This field indicates a predetermined number (for instance, "0x7137").

"Message Type": This field indicates a predetermined number (for instance, "0x84").

"Message Field": This field includes the following messages: Target MAC Address.

7. Seventh Frame

The terminal device 22 uses this frame to ask the wireless communication device 21 as to whether a link between the base station 12 and the wireless communication device 21 has been established.

"Destination Ethernet Address": This field indicates Ethernet MAC address of the base station 12.

"Source Ethernet Address": This field indicates Ethernet MAC address of the terminal device 22.

"Payload Protocol": This field indicates a predetermined number (for instance, "0x7137").

"Message Type": This field indicates a predetermined number (for instance, "0x05").

"Message Field": This field does not include any messages.

8. Eighth Frame

The wireless communication device 21 uses this frame to response to an inquiry made by the terminal device 22 using the seventh frame.

"Destination Ethernet Address": This field indicates Ethernet MAC address of the terminal device 22.

"Source Ethernet Address": This field indicates Ethernet MAC address of the wireless communication device 21.

"Payload Protocol": This field indicates a predetermined number (for instance, "0x7137").

"Message Type": This field indicates a predetermined number (for instance, "0x85").

"Message Field": This field includes the following message: Target MAC Address, if a link has been established, but does not include any messages, if a link is interrupted.

9. Ninth Frame

When the base station 12 transmits "TSIP Update Message" to the router 11, the base station 12 produces the ninth frame. An example of the ninth frame is illustrated in FIG. 5.

"Destination Ethernet Address"; This field indicates Ethernet MAC address of the router 11.

"Source Ethernet Address": This field indicates Ethernet MAC address of the terminal device 22 which has transmitted "TSIP Update Message"

"Frame Payload Protocol": This field indicates Internet Protocol.

"Frame Payload": This field copies the "Value" field of "TSIP Update Message" which was transmitted from the wireless communication device 21 to the terminal device 22 when a link has been established, and then, transmitted from the terminal device 22.

Hereinbelow is explained factions of the wireless communication system in accordance with the embodiment.

1. Notification of Network Information

In the road network 1, the router 11 transmits the above-mentioned fourth frame to the base stations 12, just after the router 11 and the base stations 12 have been started up. Before transmitting the fourth frame, the router 11 inserts Ethernet MAC address of the router's node into Target MAC address in the fourth frame, and further inserts information about a location of the router 11 within the road network 1, into Base Station Information in the fourth frame.

On receipt of the fourth frame from the router 11, each of the base stations 12 stores the frame in the memory 123 as RSU data, and uses the thus stored RSU data to carry out later mentioned steps when the base station 12 has established a link with the wireless communication device 21. When the base station 12 receives a plurality of the fourth frames from the router 11, the base station 12 rewrites the previous fourth frame with the newly received fourth frame.

2. Reservation of Movement Notification

In the automobile network 2, the terminal device 22 transmits the above-mentioned first frame to the wireless communication device 21, just after the terminal device 22 and the wireless communication device 21 have been started up. Before transmitting the first frame, the terminal device 22 inserts Ethernet MAC address of a node of the terminal device 22 into Target MAC address of the first frame, and further inserts TSIP Update Message into the first frame, if necessary.

On receipt of the first frame from the terminal device 22, the wireless communication device 21 stores the frame in the memory 212 as terminal device data, and uses the thus stored terminal device data to carry out later mentioned steps when the wireless communication device 21 has established a link with the base station 12. When the wireless communication device 21 receives a plurality of the first frames from the terminal device 22, the base station 12 rewrites the previous first frame with the newly received first frame.

3. Establishment of Link

When the base station 12 has established a link with the wireless communication device 21, the base station 12 transmits both Ethernet MAC address of the router 11 and Base Station Information stored as RSU data, to the wireless communication device 21. The wireless communication device 21 transmits Ethernet MAC address of the terminal device stored in the memory 212 as the terminal device data, to the base station 12. If the wireless communication device 21 stores TSIP Update Message in the memory 212, the wireless communication device 21 also transmits TSIP Update Message to the base station 12.

The base station 12 stores Ethernet MAC address of the terminal device 22 having been received from the wireless communication device 21, in OBE list. If Target MAC Address included in the above-mentioned third frame received from other base station 12 includes Ethernet MAC address identical with Ethernet MAC address stored in the memory 212, Ethernet MAC address stored in the memory 212 is deleted. The base station 12 stores Ethernet MAC address of the router 11 and Base Station Information both having been received from the wireless communication device 21, in the memory 212 as RSU data.

4. Movement Notif