JP2006229893A - Radio communication system and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system and its method wherein handover is simply possible at high speed in movement at the time of transmission of high traffic. <P>SOLUTION: On a base station side, an intersect adapter 5 is arranged in addition to a gate way part 3. On a mobile terminal 10, an intersect client 12 which establishes communication with the intersect adapter 5 is arranged. The intersect adapter 5 informs an identification number information of a packet which has been transmitted to the intersect client 12 to other intersect adapters 5 through a communication network between intersects, so that each of the intersect adapters 5 shares identification number information of the transmitted packet. Consequently, the newest packet can be sent out without interruption from each access point at the time of handover. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication system in a multi-cell environment in which a plurality of access points are connected to a control router and a mobile terminal communicates with each other while performing handover, and more specifically, a communication method in the system. The present invention relates to a technology for speeding up and facilitating.

  Currently, a new generation (fourth generation) wireless access system is being studied in various institutions. In this system, there is a possibility that traffic of 100 Mbps or more is transmitted not only on a wired line but also on a wireless line when moving at high speed.

  However, in the conventional handover technique, since information on transmitted packets is communicated between the access points constituting the cell or is notified from the mobile terminal to the new access point, the handover takes time. is there.

In particular, in the new generation wireless access system as described above, high traffic information is transmitted, and in order to perform inter-cell handover during high-speed movement, a marked increase in speed is required.
Conventionally, there is a technique disclosed in Patent Document 1 as a technique for speeding up handover in a multi-cell environment.

JP 2003-37626 A

  The technology allocates multicast packets statically or dynamically to a mobile terminal moving between a plurality of subnets, transmits the multicast packet from the transmission source to the mobile host, and the mobile terminal performs handover In some cases, multicast packets are delivered to both of the two subnets involved in the handover.

The present technology focuses on the fact that a multicast address is commonly used among a large number of hosts and terminals. That is, the transmission source host transmits the transmission data to the mobile terminal using a multicast packet. On the other hand, when the mobile terminal moves to another cell, it requests the upstream router to deliver the received multicast packet to both the cells before and after the movement.
Then, after moving to the subsequent cell, the router is notified that the delivery of the multicast packet to the previous cell is unnecessary.

  Such a method designates a cell from the mobile terminal to the gateway router and is excellent in versatility, but requires a complicated communication request and cannot realize high-speed switching.

  The present invention was created in view of the above-mentioned problems of the prior art, and provides a radio communication system and method capable of performing handover at high speed and easily even during movement during high traffic transmission. Objective.

In order to solve the above-described problems, the present invention provides the following wireless communication system.
That is, the invention described in claim 1 includes a control router connected to an upper network that is a predetermined packet communication network, a plurality of access points are connected to the control router, and a mobile terminal is connected between the access points. Provided is a multi-cell wireless communication system that performs communication while performing a handover.
The control router includes a gateway unit for connecting to a higher-level network, and intersects corresponding to each access point connected by an inter-intersecting communication network on the route between the gateway unit and each access point. Insert an adapter. On the other hand, the mobile terminal is provided with an intersect client unit that establishes communication with the intersect adapter unit.

  In this configuration, each intersect adapter unit transmits the identification number information of a packet transmitted to the intersect client unit to other intersect adapter units via the inter-intersecting communication network. The identification number information of the completed packet is configured to be sharable.

  According to the second aspect of the present invention, it is possible to provide a configuration using a format that transmits an Ethernet frame in at least one communication between an intersecting communication network or an intersecting adapter unit and an intersecting client unit. Can do.

  According to a third aspect of the present invention, the upper network is an IP network, and GRE (Generic Routing Encapsulation) that transmits an Ethernet (registered trademark) frame is used for the format.

  According to the fourth aspect of the present invention, the high-order network is an IP network, and one of the intersect adapter units includes at least the identification header information of the packet for the transmission data from the gateway unit. A bit is added and the copy is distributed to other intersect adapter units, while each received intersect adapter unit obtains at least the identification number information of the packet from the intersect header bits, and the intersect client unit Toward this, a configuration is provided in which data including the identification number information is transmitted using GRE (Generic Routing Encapsulation) that transmits an Ethernet (registered trademark) frame.

The present invention can also provide a communication method in the above wireless communication system.
That is, according to the fifth aspect of the present invention, a control router connected to an upper network that is a predetermined packet communication network is provided, a plurality of access points are connected to the control router, and a mobile terminal is connected between the access points. And a wireless communication method in a multi-cell environment in which communication is performed while performing handover.

  The control router includes a gateway unit for connecting to a host network, and an intersect adapter unit corresponding to each access point connected by an inter-intersecting communication network on the route between the gateway unit and each access point Is installed. On the other hand, an intersect client unit is provided in the mobile terminal.

  In such a configuration, the method of the present invention includes a step in which the inter client unit periodically makes a connection request to the intersect adapter unit, and a response notification from the received intersect adapter unit. A process of establishing communication between the intersecting adapter unit, a step of transmitting transmission data including packet identification number information to the intersecting client unit, and an intersecting client unit transmitting the identification number information to the intersecting client unit. A step of notifying the adapter unit, and the intersecting adapter unit includes a step of notifying the other intersecting adapter unit of the identification number information via the inter-intersecting communication network.

  The invention described in claim 6 provides a configuration that uses a format that transmits an Ethernet frame in at least one of the communication between the intersecting communication networks or between the intersecting adapter unit and the intersecting client unit. It is.

  The seventh aspect of the invention is characterized in that the upper network is an IP network and GRE (Generic Routing Encapsulation) that transmits an Ethernet (registered trademark) frame is used for the format.

  According to an eighth aspect of the present invention, an upper header network is an IP network, and one of the intersect adapter units includes an intersect header bit including at least identification number information of the packet with respect to transmission data from the gateway unit. And the copy is distributed to other intersect adapter units, while each received intersect adapter unit obtains at least the identification number information of the packet from the intersect header bits and sends it to the intersect client unit. For this, a configuration is provided in which data including the identification number information is transmitted using GRE (Generic Routing Encapsulation) that transmits an Ethernet (registered trademark) frame.

By providing the above configuration, the present invention can perform inter-cell handover during high-speed movement even when high-traffic information is transmitted, and can be applied to existing networks.
In particular, by using a GRE packet between the mobile terminal and the intersect adapter unit, it is possible to perform communication while confirming data delivery even in a commercial IP network.

Hereinafter, embodiments of the present invention will be described based on examples shown in the drawings. The embodiment is not limited to the following.
Figure 1 shows the system configuration. In the present embodiment, the IP network (1) is used as an upper network for performing data communication. An arbitrary network using a packet communication method can be used as the upper network.

The control router (2) connected to the IP network (1) is one of the main parts constituting the present invention.
The control router (2) includes a known gateway unit (3) connected to the IP network (1) and a plurality of intersect adapter units (5) connected thereto by a transmission path (4).

  Between the plurality of intersect adapter units (5), a transmission path called a roadside network (4a) capable of communication between mutual intersect adapters is provided, and a gateway (3) between the intersect adapter units as will be described later. It is possible to send and receive signals independently of the.

Furthermore, the access point (6) which comprises the cell in a radio | wireless communications system is each connected with the said intersect adapter (5), and forms the radio | wireless communications system of a multicell environment.
The configuration of the access point (6) is well known, and includes a modulation / demodulation processing means for performing wireless communication, a frequency conversion processing means, an antenna, and the like.

  In the present invention, in addition to the configuration on the base station side configured by the conventional gateway unit (3) and the access point (6) as described above, an interface is provided between the gateway unit (3) and the access point (6). One feature is that the sect adapter (5) is provided. Details of the intersect adapter section (5) will be described later.

  Here, in this embodiment, the intersect adapter unit (5) is included in the control router (2). However, the device may be provided externally, and any device on the route to the access point (6) may be provided. What is necessary is just to arrange | position. This path can be connected by Ethernet (registered trademark) or an optical fiber.

Further, even when the connection at the IP layer that sandwiches the IP router in the middle route such as the regional IP network is replaced, the Ethernet (registered trademark) transparent communication between the intersect adapter unit (5) and the access point is performed using the tunneling technology. Can be realized.
Any wireless communication system can be connected by appropriately changing the interface with the intersect adapter unit (5).

Next, the configuration of the mobile terminal (10) will be described.
The mobile terminal is provided with a wireless client unit (11) that performs wireless communication with the access point (6) and an intersect client unit (12) connected thereto.
A single or a plurality of computers (13) can be connected to the intersect client unit (12) so that data to be transmitted / received can be used.

  The wireless client unit (11) includes a known wireless LAN card, mobile phone communication card, PHS communication card, and the like, and includes modulation / demodulation processing means, frequency conversion means, antennas and the like.

The intersect client unit (12) establishes communication with the intersect adapter unit (5) to communicate information related to control of data transmission.
As an example of this communication, in the present invention, the unique adapter number information given to the transmitted / received packet is exchanged, whereby the intersect adapter unit (5) that first transmitted the transmitted packet on the intersect adapter unit (5) side. Can be recognized. By sharing this information between intersecting adapter units (5), the present invention realizes a fast handover.

Hereinafter, the communication direction in the downlink direction (the direction from the base station side to the mobile terminal side) according to the present invention will be described in detail.
FIG. 2 is an explanatory diagram showing the configuration of IP data in the gateway unit (3) and the intersect adapter unit (5).
As a basic communication method, first, downlink IP data is converted into a packet (referred to as an IS packet) with a sequence number (identification number of each packet) that can communicate between intersecting adapter units (5).

As shown in the figure, IP data (20) longer than a predetermined length is divided into a plurality of blocks (21), (22) and (23) within a predetermined length.
Furthermore, an IS packet is constructed by adding an IS header (24) (25) (26) including a sequence number to the head of each block. In this embodiment, the IS packet has an upper limit of 1500 bytes.

Each IS packet is copied and transmitted to other intersect adapter units (27) and (28) via the roadside network (4a) of the transmission path.
In each of the intersect adapter units (27) and (28), the IS header is extracted, and information such as a sequence number is extracted. Then, the blocks are combined and transmitted to the corresponding access points (29) and (30).

The configuration of the IS header is shown in FIG. The IS header has a total length of 60 bytes, and includes a sequence number (31) after 4 bytes, a data length after 16 bytes, a sequence number of data after 24 bytes, and the like. The following table shows the contents of the symbols in FIG.

The specific process of the intersect adapter unit (5) is as shown in FIG.
That is, in step 1 (S1), the received downlink IP data addressed to each mobile terminal is buffered.
In step 2 (S2), the intersect client unit (12) in each mobile terminal makes a connection request to each intersect adapter unit (5) via the access point (6) corresponding to the position of the mobile terminal. The intersect adapter unit (5) is connected to the intersect client unit (12).

Further, it transmits downlink IP data to the connected intersect client unit (12) (S3) and confirms its delivery (S4). For the delivery confirmation, transmission of the ACK signal is sufficient.
In step 5 (S5), the sequence number of which delivery has been confirmed is notified to the other intersect adapter unit (5).
As a result, communication can be continued even if the access point and hence the intersect adapter unit (5) are changed by the handover.

Here, at the time of the handover in the present invention, when the communication connection from the access point (6) currently communicating and the intersect adapter unit (5) is confirmed, the intersect client unit (12 in each mobile terminal). ) Makes a periodic connection request (transmission of a periodic confirmation message) to the intersect adapter unit (5).
This is a procedure for receiving a response notification from the intersect adapter unit (5), setting an IP address, etc., establishing a link, and performing a handover.

  Regarding uplink data, in order to continue communication after the above-described link is established, the mobile terminal side knows how far it has been delivered, and may send it out from the next IP data.

  Broadcast and unicast ether frames are used for communication between the intersect adapter section (5) and the intersect client section (12). For this reason, the communication path of the wireless communication system used in the present invention needs to transmit the Ethernet frame.

FIG. 5 shows the protocol stack used in the handover of the present invention, and FIG. 6 shows the transmission range of the Ethernet frame.
Further, in order to support various wired networks, the sequence number is also used for IP data delivery confirmation from the intersect client unit (5) to the intersect client unit (12).

  As a sequence numbering method, GRE (Generic Routing Encapsulation), which is an encapsulation / tunneling format used in routers, Mobile IP, and 3GPP2, is used.

In FIG. 5, the IP control part is GRE. Ethernet (registered trademark) is normally transmitted and received as an IP packet, and an IP packet and various protocols are encapsulated and transmitted after the IP header 20 bytes + GRE header 8 bytes.
As a basic method of using the GRE header, the MAC address (DA (40), SA (41) in FIG. 6) in the Ethernet header is used as the identifier of the IS adapter / client.

  In addition, the IP packet on the downlink (from the adapter side to the client side) includes a sequence number, and the uplink packet includes the last received downlink sequence number as an Ack number, so that the adapter side can receive data up to the received Ack number. Are considered delivery confirmed.

  FIG. 7 shows a packet configuration based on GRE transmitted between the access point (6) and the mobile terminal (10). Table 1 shows a message format used for handover.

Next, each function according to the present invention will be described in detail.
First, the connection / disconnection function between the mobile terminal and the access point / intersecting client unit will be described.
The intersect client unit (12) detects whether or not the connection is possible under any of the following conditions, and transmits a terminal connection request message to the intersect adapter unit (5).
(Condition 1) Independent of L2 (layer 2) connection, a message is repeatedly transmitted from a terminal at a constant period. A connection is detected when a response is received.
(Condition 2) The communication media client detects the L2 connection and notifies this to the intersect client unit (12).

The intersect adapter unit (5) / intersect client unit (12) uses the connection and disconnection functions using the message format shown in Table 1 based on the packet configuration of FIG.
Here, the Ack / sequence number is used for IP data delivery confirmation described later. Both the transmission source and destination MAC addresses / IP addresses are set as broadcast addresses and transmitted, and the intersect client unit (12) receives them.

Next, the IP address assignment function will be described. In the case of initial connection, the terminal connection message described above is used for IP address assignment from the control station to the mobile terminal.
If the client terminal already has an IP address (in the case of handover connection), the assigned IP address is used. However, the intersect adapter unit (5) basically uses the MAC address regardless of whether or not the IP address is used. The mobile terminal is identified by This specific assignment method will also be described later.

The disconnection detection and terminal disconnection functions when going out of the cell are as follows.
The intersect adapter unit (5) / client detects the disconnection of the terminal under the following conditions.
(Condition 1) When the periodic check from the intersect client section (12) is interrupted (in this embodiment, it is set to three consecutive times), the intersect adapter section (5 ) Detects terminal disconnection. Similarly, the intersect client unit (12) of the mobile terminal detects terminal disconnection when the response from the intersect adapter unit (5) is interrupted.
(Condition 2) The access point / mobile terminal detects L2 (Layer 2) disconnection and notifies the intersect adapter unit (5) / intersect adapter unit (5).

The data transmission / reception / delivery confirmation function on the base station side and mobile terminal side of the present invention will be described below.
In the following description, it is assumed that all downlink messages (from the control router to the mobile terminal) including IP data packets include a sequence number for delivery confirmation using the GRE mechanism.
Also, all uplink messages (from the mobile terminal to the control router) include the downlink packet sequence number that has been received by the mobile terminal as an Ack number.

The intersect adapter unit (5) that has received this Ack number regards data up to the number as having been transmitted, and notifies other intersect adapter units (5) through the roadside network (4a).
When transmitting a downlink IP data packet, a sequence number obtained by incrementing the last transmitted sequence number by 1 is included in the sequence number portion of the GRE header and transmitted.

The sequence number is also included when other control data such as a terminal connection response message is transmitted, but here, the sequence number sent last is included without being incremented.
In the case of uplink packet transmission, the last received sequence number is included as an Ack number in all transmission packets regardless of the packet type.

When the intersect adapter unit (5) does not receive the Ack within a certain time from the time point when the latest downlink IP data packet is transmitted, the intersect adapter unit (5) retransmits the subsequent packets from the downlink IP data packet of the next sequence number that has already received the Ack.
At this time, the mobile terminal side needs to set the waiting time for Ack batch transmission shorter than the retransmission waiting time for the control station.

A handover function in the wireless communication system of the present invention will be described.
In the method of the present invention, all uplink messages such as period confirmation and terminal connection include the sequence number of the downlink IP data packet last received by the mobile terminal as an Ack number.
The intersect adapter unit (5) that has received the Ack number shares the sequence number that has been confirmed for delivery to the mobile terminal with the other intersect adapter unit (5) by the broadcast mechanism in the roadside network (4a). To do.

Thus, if the access point and the intersect adapter unit (5) to which the mobile terminal is connected are changed in the middle of communication, the IP data packet is received from the continuation of the received sequence number in the change destination intersect adapter unit (5). be able to.
According to this configuration, seamless and high-speed handover can be realized without causing a delay at the time of handover, which is a conventional problem.

In the present invention, as a function to apply the handover function as described above, a function of performing control to switch communication media used by the mobile terminal can be implemented.
The mobile terminal can use each communication medium in turn or at the same time, and can perform handover between the intersect client units (12) in charge of the media used at that time.
Further, as shown in FIG. 1, when connecting a plurality of client terminal computers, it can be easily realized by using an IP masquerade function or the like on a client terminal connected as a standard.

In the present invention, the following IP tunnel processing is performed to enable use of the Internet or a wide area private network service between the intersect adapter unit (5) and the access point.
First, the Ethernet frame received from the intersect adapter unit (5) or the access point is transmitted to the router side by a normal IP / Ethernet packet transmission means as an encapsulated packet (GRE, TCP, etc.) on the IP protocol.
The encapsulated packet received from the router is extracted from the Ethernet frame and sent to the intersect adapter unit / access point as it is.

The function of the control router (2) will be described in detail below.
FIG. 8 shows the structure of the intersect adapter (5) which is a feature of the present invention. Basically, it consists of an IP data control unit (50), a wireless communication device control unit (51), and an IS network communication control unit (52), and has a maintenance operation management control unit (53) for performing other management control. ing.

First, the functions of the IP data control unit (50) will be described in order.
(1) IP address cache function This function pools IP addresses for mobile terminal terminal allocation received in response to an IP address cache request from the gateway unit (3), and manages whether to allocate to mobile terminals. At the same time, the DNS server address is also received from the gateway unit (3) and managed for mobile terminal notification.

(2) IP address assignment function The sequence at the time of IP address assignment is as follows.
(A) Upon receipt of a periodic confirmation message from the mobile terminal, it detects that it has entered the wireless service area and transmits a periodic response message to the mobile terminal.
(A) When a terminal connection request (IP allocation) is received, after confirming that the IP address has not been set, it is obtained in advance from the gateway unit (3) and given an address in the cache table. Then, the acquired IP address is set in the terminal connection response (IP assignment) message and notified to the mobile terminal.
(C) At the same time, an IP assignment notification is transmitted to the other intersect adapter unit (5) in the same control router through the IS network, and the IP management table in the adapter is updated.

(3) IP address inspection function (a) In determining a mobile terminal to which an IP address has been assigned, it is determined by whether or not the IP address field of the terminal connection request message has been set.
(A) In the IP address inspection, if it is registered in the IP address / MAC address correspondence table, matches the registered information, or is unregistered or does not match the registered information, the IP address inspection result of the gateway unit (3) Check if is OK.
(C) In transmitting the IP address inspection result, the inspected IP address is set in the terminal connection response message and transmitted to the mobile terminal. The DNS server address is also transmitted at the same time in the same message. An IP address setting completion notification is received from the mobile terminal.
(D) In the correspondence management between the inspected IP address and the mobile terminal terminal MAC address, the IP address / MAC address correspondence table is updated, and the correspondence information of the inspected IP address is notified to the IS network by the IP address confirmation notification. . Each received control station updates its own IP address / MAC address correspondence table.

(4) Mobile terminal connection disconnection management function (a) In mobile terminal information registration in the mobile terminal connection management table, when a new IP address is assigned to a terminal connection request from the mobile terminal, and an IP address check When it is assigned again because of NG, the information of the mobile terminal is registered when the IP address setting completion notification is received. In response to a terminal connection request from a mobile terminal, if the IP address has been assigned and the IP address check is OK, the mobile terminal terminal information is registered after the terminal connection response is transmitted.
(A) In deleting the mobile terminal terminal information from the mobile terminal connection management table, the mobile terminal information is deleted from the management table when a disconnection notification is received from the mobile terminal.

(5) IP data transfer function This function receives an IP data request from a mobile terminal and transmits it to the IP network via the gateway unit (3). The IP data is stored in the network, and the IP data is transferred to the connected mobile terminal. Confirmation of IP data delivery and retransmission are also performed.
(A) In receiving an IP data request from a mobile terminal, IP data is transmitted to the IP network in response to the IP data request from the mobile terminal.
(A) In accumulating the IP data response, the control station that has received the IP data response from the IP network registers the IP data response as accumulated IP data information in the IP data control table.
(C) In the IP data response transfer to the mobile terminal, when the IP data response is received from the IP network, the destination IP address of the IP data response is registered in the mobile terminal connection management table. The stored IP data information is transferred to the mobile terminal.
(D) In IP data delivery confirmation and retransmission, an IP data delivery confirmation is received from the mobile terminal, and all stored IP data information before the received sequence number is deleted from the IP data control table. Time-out monitoring of IP data delivery confirmation is performed, and when the IP data delivery confirmation cannot be received within the time limit, the stored IP data information is retransmitted.

(6) Handover function A function for receiving an IP data delivery confirmation from a mobile terminal and transmitting the IP address, MAC address, and received sequence number of the source mobile terminal to the roadside network as takeover information and the takeover information from the roadside network. There is a function of deleting all stored IP data information before the received sequence number from the IP data control table corresponding to the received and notified IP address and MAC address.

Next, functions of the wireless communication device control unit (51) will be described.
(1) IP address assignment / inspection function (a) Upon receipt of a periodic confirmation message, the mobile terminal detects that the mobile terminal has entered the wireless service area and transmits a periodic response message to the mobile terminal.
(A) When a terminal connection request (IP allocation) is received, an IP address acquisition request is made to IP data control, and a MAC address and a global IP address (client IP) that can be allocated to a client computer are acquired.
(C) Set the acquired IP address in the terminal connection response (IP assignment) message and notify the mobile terminal.
(D) When the IP address setting completion notification is received, the result is notified to the IP data control unit (50).

(2) IP data request reception function (a) When a data IP packet is received, the received packet is notified to IP data control.
(B) IP data control creates an IS packet from the received data and transmits it to the roadside network.

(3) IP data response transmission function (a) The IP data control notifies the wireless communication device control of the IS packet for the client terminal received from the IS network.
(A) Create a data IP packet from the received data and notify the mobile terminal.
(C) When the delivery confirmation is received, the delivery confirmation is notified to the IP data control.

(4) Terminal connection notification function (A) The mobile terminal transmits a cycle confirmation message to the control station at a preset cycle.
(A) Upon receiving the period confirmation message, the control station detects that the mobile station has entered the wireless service area, and performs IP address assignment / inspection processing. However, it is also possible to detect the immediate terminal connection by the layer 2 function without using the period confirmation message.

(5) Terminal disconnection detection function (A) The mobile terminal notifies the control router side of the periodic confirmation at a predetermined cycle, and the control router that has received the notification repeats the process of transmitting a periodic response to the mobile terminal. .
(B) If the periodic confirmation cannot be received within the specified time, it is detected that the mobile terminal has moved out of the wireless service area, and terminal disconnection processing is performed. However, it is also possible to detect the immediate terminal disconnection by the layer 2 function without using the period confirmation message.

The functions of the IS network communication control unit (52) are as follows.
(1) Broadcast communication function In the broadcast communication method, the transmission source transmits a packet to all intersect adapter units (5) connected to the IS network. In this method, only necessary packets are fetched and processed.
(2) Fragment function When the data size requested by the access point on the sending node exceeds IS header + AP data = 1500 bytes, the packet size is divided into 1500 bytes or less by roadside network communication control. (1) Data A serial number and (2) a fragment serial number are assigned and transmitted. On the receiving node side, data assembly is performed by roadside network communication control based on each serial number.

The data sequence number and fragment sequence number are as follows.
(A) Data sequence number The data sequence number is used to associate fragmented packets.
(B) Fragment serial number Fragment serial numbers are assigned at the time of fragmentation and divided and assembled.
(C) Flow of packet division / assembly On the transmission side, the AP data is divided so as to be less than the maximum length (1500 bytes-IS header length), the IS header is edited, and the data is sequentially transmitted. The receiving side assembles AP data according to the contents of the IS header, and notifies the access point when the assembling is completed.

(3) Packet sequence number assigning function This function is a function for assigning serial numbers to all packets transmitted on the transmission node side. When one packet is taken out from the transmission queue and transmitted, a packet serial number is assigned and the packet is transmitted. After transmission is complete, add +1 to the packet sequence number. However, checking for missing packets by serial number is not supported.

The configuration of the present invention is as described above.
Finally, in order to verify the handover function, the handover time shown in FIG. 9 was measured by the system shown in FIG. As the handover time, the time for switching to one intersect adapter section (5) and the other intersect adapter section (5) in the control router (2) was measured.

Then, the time T1 until the link to one intersect adapter unit (5) is broken and the disconnection is detected in the intersect client unit (12), and then the IS adapter from the intersect client unit (12). After the other intersect adapter unit (5) is found by the period confirmation message and the IP is set, the time T2 until the link is established is measured.
The sum of T1 and T2 is the switching time. Here, the periodic confirmation message is transmitted every 100 ms in the test apparatus.

Particularly in this experiment, T2 depends on the intersect adapter unit (5) and the wireless access system connected to the IS client. In this experimental example, measurement was performed using a wireless LAN access point and a mobile terminal wireless device.
As a result of the experiment, when the period confirmation message cannot be taken about three times, T1 is regarded as a disconnection, and the time is from 300 ms to 400 ms. T2 has a long wireless LAN association time, which averaged 3808 ms.
Therefore, it takes about 4108ms to 4208ms switching time. However, this mostly depends on the type of wireless LAN association and its basic configuration time, and it has been shown that the time of the handover process itself in the present invention is sufficiently short like T1.

1 is an overall configuration diagram of a wireless communication system of the present invention. It is explanatory drawing which shows the relationship between an IP packet and IS packet. It is explanatory drawing which shows the structure of IS header. It is a flowchart of the data transmission of a downlink direction. It is explanatory drawing of the protocol stack at the time of the handover by this invention. It is explanatory drawing explaining the transmission range of the ether frame in a present Example. It is a block diagram of the packet transmitted between an access point and a mobile terminal. It is a block diagram of a control router. It is a sequence diagram which shows the procedure of the hand-over in an experiment example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 IP network 2 Control router 3 Gateway part 4 Transmission path 4a Road side network (IS network)
5 Intersect Adapter 6 Access Point 10 Mobile Terminal 11 Wireless Client 12 Intersect Client 13 Client Computer

Claims (8)

A wireless communication system in a multi-cell environment comprising a control router connected to a higher-level network that is a predetermined packet communication network, connecting a plurality of access points to the control router, and a mobile terminal communicating with each other while performing handover Because
The control router includes a gateway unit for connecting to a host network, and an intersect adapter corresponding to each access point connected by an inter-intersecting communication network on the route between the gateway unit and each access point Intervening,
The mobile terminal is provided with an intersect client unit that establishes communication with the intersect adapter unit,
The intersect adapter unit notifies the other intersect adapter unit of the identification number information of the transmitted packet to the intersect client unit to the other intersect adapter unit via the inter-intersecting communication network. A wireless communication system characterized in that identification number information can be shared. The wireless communication system according to claim 1, wherein a format for transmitting an Ethernet frame is used in at least one of the communication between the intersecting communication networks or the intersecting adapter unit and the intersecting client unit. The wireless communication system according to claim 2, wherein the upper network is an IP network, and GRE (Generic Routing Encapsulation) that transmits an Ethernet frame is used for the format. The upper network is an IP network, and one of the intersect adapter units is:
While the transmission data from the gateway part adds an intersect header bit including at least the identification number information of the packet and distributes the copy to other intersect adapter parts,
Each received intercept adapter unit obtains at least the identification number information of the packet from the intersect header bit, and performs GRE (Generic Routing Encapsulation) that transmits an Ethernet (registered trademark) frame toward the intersect client unit. The wireless communication system according to claim 2, wherein data including the identification number information is transmitted. A wireless communication method in a multi-cell environment, comprising a control router connected to a higher-level network that is a predetermined packet communication network, connecting a plurality of access points to the control router, and allowing a mobile terminal to communicate while handing over each access point Because
The control router includes a gateway unit for connecting to a host network, and an intersect adapter corresponding to each access point connected by an inter-intersecting communication network on the route between the gateway unit and each access point Intervening,
The mobile terminal has an intersect client part,
The inter-client unit periodically makes a connection request to the intersect adapter unit;
A step of establishing communication with the intersect adapter unit by a response notification from the received intersect adapter unit;
The intersect adapter unit transmits transmission data including packet identification number information to the intersect client unit,
A process in which the intersect client unit notifies the intersection adapter unit of the identification number information;
The wireless communication method comprising: a step of notifying the identification number information to another intersect adapter unit through the inter-intercept communication network. The wireless communication method according to claim 5, wherein a format that transmits an Ethernet frame is used in at least one of the communication between the intersecting communication networks or the intersecting adapter unit and the intersecting client unit. The wireless communication method according to claim 6, wherein the upper network is an IP network and uses GRE (Generic Routing Encapsulation) that transmits an Ethernet (registered trademark) frame in the format. The upper network is an IP network, and one of the intersect adapter units is:
While the transmission data from the gateway part adds an intersect header bit including at least the identification number information of the packet and distributes the copy to other intersect adapter parts,
Each received intercept adapter unit obtains at least the identification number information of the packet from the intersect header bit, and performs GRE (Generic Routing Encapsulation) that transmits an Ethernet (registered trademark) frame toward the intersect client unit. The wireless communication method according to claim 6, wherein data including the identification number information is transmitted.

Images