JP2005341300A - Radio communication system, and radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain communication even if a radio communication terminal is out of the communication range. <P>SOLUTION: In the situation where radio communication terminals MN1, MN2 perform communication via a base station AP1 within a communication range 50 of the base station AP1, the radio communication terminal MN1 measures a receiving radio wave intensity RRSI from the base station AP1 to detect trial of moving outside the communication range of the base station AP1, and the radio communication terminal MN1 starts handover operation. Ordinarily, another peripheral communicable base station is found out to perform handover but if other base stations are not present at all, a relief signal requesting relay of data to the base station AP1 is transmitted to the radio communication terminal MN2 with which the own terminal MN1 communicates and which is located within the communication area 50 of the base station AP1. When the radio communication terminal MN2 receives this relief signal, the radio communication terminal MN2 serves as a repeater station between the radio communication terminal MN1 and the base station AP1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a network communication technology using radio, and more particularly to a handover technology in mobile communication used in a wireless LAN (Local Area Network) or the like.

  In recent years, wireless LAN systems using a high frequency band such as a 2.4 GHz band or a 5 GHz band have become widespread, and it has become possible to easily use a wireless network. Accordingly, information devices such as a PC (personal computer) or a PDA (personal digital assistant) have a communication terminal function for performing wireless communication. Furthermore, there are increasing opportunities to make calls and data communications to remote locations using portable wireless communication terminals such as mobile phones and PHS.

  The difference between wireless communication and wired communication is advantageous in that wireless communication eliminates the concept of wiring. However, since there is no wiring, any device capable of transmitting and receiving radio waves can transmit and receive wireless communication. Therefore, in wireless communication technology, using encryption technology, frequency setting, frequency modulation technology, time division technology, communication management number, there is no interference or crosstalk, and in a state of keeping secret You can now send and receive safely.

  The reason why general wireless communication is carried out only in a cell (a specific zone) centered on a base station called a cellular network is that the base station is responsible for the confidentiality of terminals existing in the cell. It is relatively easy to ensure reliability and reliability of communication.

  Various wireless communication terminals can perform data communication with other wireless communication terminals via the base station by accessing the base station AP. That is, a wireless communication terminal that performs data communication needs to maintain a connection with a base station directly or indirectly through some communication device. By the way, a mobile radio communication terminal often moves out of a communicable area of a certain base station because a communication place moves. Since many base stations are fixed and the communication area cannot be easily changed, the communication area of one base station is limited. Therefore, in order to widen the communication area of the mobile wireless communication terminal, a plurality of base stations each covering a plurality of different areas are arranged and accessed according to the position of the moving wireless communication terminal. The base station needs to be changed to a nearby base station.

  As a representative technique for changing a base station to be accessed as a wireless communication terminal moves, a handover technique can be cited. The handover technology is formed by a network having a plurality of communicable areas (cells) covered by a base station, and communication can be continued without interruption when a terminal that performs communication moves and moves to an adjacent cell. Such automatic switching technology. Specifically, when the radio wave from the currently communicating base station is weak, the base station can be searched by searching for another base station that will be the next base station from around the terminal itself In this case, mediation is performed to continue communication, and communication is continued without interruption.

  7 to 9 are diagrams showing the flow of processing in the conventional handover technique. In the conventional handover technique, in FIG. 7, the mobile station 108 communicates with the opposite terminal 100 from the router 101 via the base station 106 and the router 102 in the area of the cell 201. However, there is a base station 107 that covers the cell 200 adjacent to the cell 201 and has the router 103. In general, the base station and the terminal can be connected to the WAN 104 such as the Internet. From the state of FIG. 7, it is assumed that the operation of moving the base station to be accessed is performed as shown in FIG. As shown in FIG. 8, when a handover is performed at the receiving terminal 108, the router 105 connected to the handed over base station 107 functions as a new router, and the data route from the partner (opposite terminal 100) is routed. The router 103 is requested to secure and receive it. The router 103 negotiates with the WAN (Wide Area Network) 104 and forwards the data from the router 102 to the network where the new router 103 exists.

  In the method described with reference to FIG. 7 and FIG. 8, the route change work of data communication becomes large, and the time during which data generated due to the route change is interrupted tends to be long. In addition, the base stations need to form a network connected by wire, for example.

In order to solve these problems, in the method shown in FIG. 9, the base station 106 and the base station 107 have a function of performing data transfer by wireless communication. Normally, in order to perform handover from the base station 106 to the base station 107, the mobile station 108 needs to have the router 103 connected to the base station 107 create a routing path. Therefore, by providing a transfer function that allows the base station 106 and the base station 107 to transfer data, it is possible to perform handover from the base station 106 to the base station 107 without causing the router 103 to create a routing path. . In this case, the data transmitted from the opposite terminal 100 reaches the router 102 via the router 101 and the WAN 104. Data reaching the router 102 is sent to the base station 106. Thereafter, the data is transferred to the base station 107 by wireless communication and reaches the mobile station 108 (see Patent Document 1). According to this method, handover can be easily performed.
JP 2003-333053 A

  However, the handover technique described in Patent Document 1 (FIG. 9) has the following problems. That is, since the technique shown in FIG. 9 is a mechanism centered on the base station to the last, when there are no base stations that can be handed over, a state where communication is not possible (generally called out-of-service) Communication) is interrupted. In addition, if too many base stations are provided, there is a problem that the cost is high. Such a situation in which the radio wave from the base station cannot be received occurs in communication between the same floor in the same building or in communication between different rooms in the home. It is one of the problems that should be solved when using.

  An object of the present invention is to provide a new wireless communication technology that can maintain communication even when a wireless communication terminal goes out of service area while maintaining the existing technology basically.

The wireless communication technology according to the present invention is characterized by the following configuration.
1) A wireless communication terminal performs wireless transfer (relay) with confidentiality and certainty. At this time, the base station is not particularly set to change the data path. If it is wired, it is possible to analyze the flowing data as it is and transfer the data to the data line corresponding to the physical address of the destination terminal. However, in radio, it is necessary to demodulate the received data and check whether it is the corresponding data, and when transferring, since it is necessary to modulate and transmit again, it may be simply transferred. Can not. Therefore, it is necessary to make the above situation. The relay station may be in communication or on standby.
2) Since data is relayed to the base station side even though data is relayed to the terminal side, the relay terminal obtains the terminal ID and encryption key information of the transfer destination terminal. Forward. In this case, it usually does not impersonate for security reasons.
3) When the terminal goes out of the area, it performs a new handover by issuing a special rescue protocol. This new handover target is characterized in that it is not a handover to a base station but a terminal.
4) When the relay station relays, the following two operations are possible. The first operation is an operation of impersonating the terminal as it is and continuing to receive data from the base station, which is based on the assumption that no data has been missed. The second operation assumes that there is a possibility that data from the base station transmitted during the work to be a relay station may be missed, and the relay station This is an operation of impersonating to receive data after performing a handover process of returning to the outside of the base station and returning again after impersonation. By performing the handover process as the second operation, the data dropped during the handover can be transferred again from the base station (data transferred at a high data rate can be obtained by doing this). Let me guarantee the data.)

  In the present invention, a wireless communication terminal can be a relay station between another terminal and a base station as necessary. As a mechanism for this, a “wireless hardware mechanism” is provided. That is, when it is determined that the terminal is out of the service area, it is provided with “Hardware” and “Firmware” that realizes a repair protocol necessary for becoming a relay station to a peripheral terminal different from the terminal, and data A driver having an “IP frame encapsulation function” for realizing the delivery of the network, and further, an operating system (hereinafter referred to as “OS”) in a device using a wireless communication device. Windows, Linux, etc.)) By using the “communication management application” that runs on the above and linking these hardware, firmware, drivers, and applications on the OS, the terminal falls into a situation that is out of service area or in a poor electric field condition. On the other hand, the relay station realizes data transfer.

  The relay station may be called a router. In this specification, a router refers to a device for flowing data flowing on a network to another network.

  ADVANTAGE OF THE INVENTION According to this invention, when the radio | wireless communication terminal which is communicating becomes out of service area, it becomes possible to provide the radio | wireless communications system which can maintain communication. For example, in a situation where the base station is not fully maintained, but there are terminals with mobile wireless communication functions such as mobile phones and personal computers other than the base station, the communication area can be expanded. As a result, there is an advantage that the out-of-service state can be reduced for the wireless communication terminal that performs communication.

  Hereinafter, a wireless communication system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 3 is a diagram illustrating a configuration example of a wireless communication system according to an embodiment of the present invention. Each terminal that performs wireless communication has an interface unit for network communication. In this embodiment, it is assumed that a network card is provided as the interface unit. The network card has, for example, the configuration shown in the system function division diagram of FIG. The protocol hierarchy diagram of FIG. 3 is a diagram showing a protocol hierarchy corresponding to each function of the system function division diagram.

  As shown in FIG. 3, when comparing the system function division diagram and the protocol layer structure diagram, on the Card side, the radio communication device RF8 and the modem PHY9 correspond to the physical layer 14. MAC 7 corresponds to the MAC layer 13. Firmware 6 and Card I / F 5 correspond to the LLC layer 12. On the HOST side, the driver 4 and the OS 3 correspond to the TCP / IP layer 11, and the allocation 1 and the connection application 2 correspond to the application layer 10.

  When the HOST of the network card is a PC, the card and the HOST are physically connected by the card I / F 5 of the network card, and the start data is transferred to the HOST side via the connection unit. In the Card, the embedded software Firmware 6 controls the device MAC 7 that performs the function of the MAC layer, the device RF 8 that performs wireless transmission and reception, and the device PHY 9 that realizes the function of the modem, and the Card I / F 5 Data transmission / reception is realized.

  The driver (driver) 4 on the HOST side sucks data from the Card side, analyzes the data, omits data such as header information, and sends this data to the host OS 3. The OS 3 analyzes the source address and destination address of the data passed as the IP frame and allocates the data to the application 1 side. Unlike the normal application 1, the connection application 2 has a function of transmitting the start and end of communication of the network interface to the Card through the Driver 4 and controlling the Card, and processes the IP frame data in the Driver 4 itself. It has a function that can issue an instruction to do. A terminal that can serve as a relay station that can exchange data includes two or more interfaces of the network in FIG. That is, it is assumed that the relay station relays data in such a manner that the data goes up to the TCP / IP layer 11 in the protocol hierarchy diagram of FIG. 3, loops back at the TCP / IP layer 11, and flows to the driver 4 of another interface.

  FIG. 10 is a functional block diagram showing a more specific configuration example of the base station AP1 or the mobile stations MN1 and MN2 constituting the wireless communication system according to the present embodiment. As shown in FIG. 10, the base station or terminal station includes an antenna 21, an antenna duplexer 22, an RF / IF receiver 23, an A / D converter 24, a demodulator 25, and a bus control unit 27 ( For example, a modulator 28, a D / A converter 29, an RF / IF transmitter 30, and a system control unit 31 are included. The system control unit 31 includes a database unit (storage unit) 31a and a notification unit 31b. Note that the block configurations of the base station AP1 and the terminal stations MN1 and MN2 have substantially the same configuration. However, some functions of the system control unit 31 are different due to a difference in functions regarding transmission and reception between the base station AP1 and the terminal stations MN1 and MN2. Moreover, you may have the function to preserve | save data in the alerting | reporting part 31b and the database part (memory | storage part) 31a.

  Next, the operation of the wireless communication system according to the present embodiment will be described with reference to FIG. 3 as appropriate. FIG. 1A is a diagram illustrating a situation in which the wireless communication terminal MN1 and the wireless communication terminal MN2 perform communication within the communication range 50 of the base station AP1 via the base station AP1. In a normal communication state, it is assumed that the base station AP1 and the wireless communication terminal MN1 are communicating with each other with a good radio field strength (RSSI). FIG. 1B is a diagram illustrating a state where the wireless communication terminal MN1 is out of the communication range 50 of the base station AP1. In the state shown in FIG. 1B, the RF circuit provided in the wireless communication terminal MN1 communicates from the base station AP1 because the value of the received radio wave intensity RSSI from the base station AP1 being measured becomes weaker. It is possible to know that the user is about to move out of the service area (for example, determination is made based on a signal received by the receiver 23 in FIG. 10). The wireless communication terminal MN1 enters the handover operation by notifying the host MAC 7 and the Firmware 6 of information indicating that the value of the received radio wave intensity RSSI becomes weak. In this situation, another base station capable of communication in the surrounding area is found and handed over, but if there is no other base station at all, the communication must be disconnected, but the wireless communication according to the present embodiment In the system, as shown in FIG. 1 (c), the wireless terminal MN2 with which the terminal MN1 has been communicating so far, the wireless communication terminal MN2 within the communication area 50 of the base station AP1 A rescue signal is transmitted to request that the terminal MN1 be rescued by transferring (relaying) data to the AP1. At this time, it may be sent in accordance with its own conditions. The relief signal may be, for example, a notification message transmitted in all directions. When the wireless communication terminal MN2 receives this relief signal, the wireless communication terminal MN2 uses a one-to-one communication mechanism to If the terminal MN2 can become a so-called relay station between the wireless communication terminal MN1 and the base station AP1, a response message to that effect is returned to the wireless communication terminal MN1.

  The wireless communication terminal MN1 saves this response message returned from all directions in a storage unit (31a in FIG. 10) such as its own database, and in the terminal (FIG. 1 (c) in FIG. A communication connection is established with the communication terminal MN2). Thereafter, as shown in FIG. 1 (d), the wireless communication terminal MN1 can continue data communication with another terminal or the like via the base station AP1 via the wireless communication terminal MN2 functioning as a relay station. .

  Hereinafter, the movement of each terminal in the wireless communication system will be described for each terminal. The terminals include a wireless communication terminal MN1 that is a “receiving terminal” and a wireless communication terminal MN2 that can function as a “relay station”. In addition, the configuration of a data packet for flowing user data will be described below.

  First, the operation of the mobile station will be described. The handover operation of the wireless communication terminal MN1 will be described with reference to FIG. Reference is made to FIGS. 1, 10 and 2 as appropriate. FIG. 5 is a flowchart showing a process flow of a handover operation mainly using the radio communication terminal MN1 in the radio communication system according to the present embodiment.

  As shown in FIG. 5, the wireless communication terminal MN1 is initially in a normal communication state as shown in step S1. From this state, detecting that the value of the radio field intensity RSSI with the base station AP1 has decreased due to the movement of the wireless communication terminal MN1 (based on the receiver 23 in FIG. 10) (step S2), In order to perform more reliable communication, first, an attempt is made to receive a notification message (step S3) issued by base stations around the wireless communication terminal MN1 (notification unit 31b in FIG. 10). If this notification message can be received, it is determined that there are base stations that can be handed over in the vicinity, and normal handover processing is started (step S4).

  In step S3, when the notification message cannot be received, a notification message (invocation request message) that prompts the activation of the relay station function possessed by the terminal is transmitted to surrounding terminals (S5). FIG. 1C illustrates a state where a notification message that prompts the activation of the relay station function is transmitted.

  After transmitting the notification message, the wireless communication terminal MN1 waits for a response message for a specific time (step S7). Thereafter, by returning to step S7, all the messages returned within this waiting time can be stored in the database (storage unit) 31a (FIG. 10) in the wireless communication terminal MN1 (step S6). The data includes information indicating the radio field strength with the base station, the base station ID, the transmission capability, the reception capability, and the MAC address in the responding terminal. By using the information of the MAC address, it is possible to determine whether or not the terminal serving as the relay station is a terminal that is illegally tapping.

  Next, when a time-out occurs, the process proceeds to step S8, and it is determined whether or not any data exists in the database 31a (FIG. 10). If there is no data, it is determined that there is no relay station, so the process proceeds to step S9 and a communication disconnection process is performed. If the data exists in step S8, the process proceeds to step S10, and the wireless communication terminal MN1 selects a terminal that functions as its own relay station from the data stored in the database 31a (FIG. 10) ( S10). At this time, as a selection criterion, for example, a terminal suitable as a relay station is selected from the “radio wave intensity RSSI” and the “free band” value. For example, the top three relay station candidate terminals are selected. After selecting an actual relay station from relay station candidates, the wireless communication terminal MN1 transmits a relay station determination notification to a terminal that functions as its own relay station (step S11). As parameters of this message, it is preferable that information on the base station identifier, the service identifier that has made the connection, the terminal identifier ID, the IP address, and the netmask information is attached and passed. In step S12, a response to the decision message is waited for, and if a time-out occurs without a response (such as when the selected terminal refuses association), the process proceeds to step S13, and whether there are other terminals in the relay station candidate. If it exists, the process returns to step S12. If it does not exist, the process proceeds to step S15 to perform communication disconnection processing. If there is a response to the determination message, the process proceeds to step S14, and the frequency band to be used is determined. At this time, the selection is made so as not to match the frequency band (or channel) used so far.

  The parameters of the message passed in step S11 are information on the identifier of the base station, the service identifier that has connected, and the terminal identifier ID, and the terminal serving as the relay station replaces the wireless communication terminal MN1 in communication with the base station AP1. These parameters are necessary for the wireless communication terminal MN2 to associate. The IP address and netmask information are necessary for correctly receiving unicast and broadcast information, which is an IP layer connection. By obtaining such information, a terminal serving as a relay station can perform data transmission on behalf of the wireless communication terminal MN1 without following the association procedure with the base station. In step S16, the IP address and netmask are temporarily changed. After determining the parameters, the communication is performed with the terminal that has selected the association in order to perform the one-to-one communication between terminals (step S17). In the state in which the association is performed, the wireless communication terminal MN1 can continuously perform wireless communication by receiving data from the wireless communication terminal MN2 that has become the relay station (step S18). FIG. 1D shows a state in which the wireless communication terminal MN1 functions as the relay station and receives data from the base station AP1. At this time, communication is performed at a frequency of A Hz between the base station AP1 and the relay station MN2, and between the relay station MN2 and the terminal station MN1 at a frequency of B Hz different from A. Through the processing as described above, communication between the terminal station and the base station can be continued via the relay station.

  Next, an operation mainly performed by a terminal functioning as a relay station will be described. The wireless communication terminal MN2 that functions as a relay station for the wireless communication terminal MN1 operates as follows.

  FIG. 6 is a flowchart showing a flow of processing for the wireless communication terminal MN2 to function as a relay station of the wireless communication terminal MN1. As shown in FIG. 6, the wireless communication terminal MN2 is in a steady standby state (step T1). The steady standby state is a state in which communication is not performed, but a state in which radio waves are received from the base station AP1. In this state, the wireless communication terminal MN2 may be in communication with the base station AP1. However, it is necessary to have sufficient communication capability to function as a relay station in parallel.

  When the wireless communication terminal MN2 receives the relay station function activation request message (issued from the notification unit 31b in FIG. 10) from the wireless communication terminal MN1 in the above-described steady standby state (step T2), the wireless communication terminal MN2 currently captures itself with the terminal MN2. The value of the radio field intensity RSSI with the base station AP1 and the available communication band (free band) between the transmitting side and the receiving side are calculated (step T3).

  At this time, the radio communication terminal MN2 determines whether or not a device functioning as a relay station has two or more network interfaces (step T4). When two or more are not provided, the process returns to step T1. When two or more are provided, a determination is made as to which of the two interfaces is used as a base station and which is used as a relay station (step T5).

  Thereafter, the wireless communication terminal MN2 returns a response message of the relay station function activation request message (step T6). However, the parameter of this message is transmitted with the above-mentioned radio wave intensity RSSI, the communication band indicating the transmission / reception capability, and the ID of the base station captured by the terminal itself. After transmitting the response message, the wireless communication terminal MN2 waits for reception of a message notifying the determination of the relay station for a certain time (step T7). If a message reception timeout occurs, the process returns to the steady standby state (step T1). If a notification of relay station decision is received before the time-out, the relay station function is activated in the IP layer (step T9), so that it can function as a relay station. In Mobile IPv6, the Home Agent function is activated. In the portion close to the physical layer, the interfaces of the two networks are set to the standby state at different frequencies (step T8).

  Next, the wireless communication terminal MN2 establishes a connection using the network interface side on the base station AP1 side. There are two ways to establish a connection. One is a state where the wireless communication terminal MN2 completely replaces the wireless communication terminal MN1, that is, the case shown in FIG. As shown in FIGS. 2 (a) and 2 (b), the physical address of the terminal MN1, the terminal identification ID, various ARQ setting values, the encryption key (DES used in the IP layer and below) are transmitted to the terminal serving as the relay station MN2. Provide information necessary for continued communication. That is, reflecting the information present in the relay station determination message, the terminal identifier ID of the wireless communication terminal MN1, the identifier of the base station, the base station service information, the physical address, and various setting values for ARQ, Data is picked up (step T11). Note that, regarding data omission, since data can be picked up by setting ARQ, the base station AP1 operates as if communication is being continuously performed.

  It is determined whether data reception can be confirmed (step T13). If data reception is possible, the wireless communication terminal MN2 determines that the connection with the base station AP1 has been established, and the wireless communication terminal MN1 determines the relay station. A message response message is transmitted (step T15). The wireless communication terminal MN1 that has received this response message performs an association operation (step T17) for performing one-to-one communication with the wireless communication terminal MN2, and enters a handover procedure when data cannot be received. (Step T12). When the association is completed, actual data is transferred (step T18).

  Another method will be described with reference to FIG. The configuration shown in FIG. 2 is a case where a terminal serving as a relay station once performs a handover operation. First, even when a terminal serving as a relay station uses a handover, Information necessary for continuing communication, such as a physical address, terminal identification ID, various ARQ setting values, and an encryption key (DES used below the IP layer). When performing a handover, providing information such as an old terminal identifier necessary for the handover eliminates the need to set the ARQ by the handover protocol operation. Although the wireless communication terminal MN2 replaces the wireless communication terminal MN1, when the handover process is performed (step T12), the above ARQ setting value is not required and the handover process is performed, so that the base station side and the terminal side Since the ARQ process is reset once, duplicate data transmission / reception occurs, leading to real-time processing and useless data transmission / reception processing, but a connection with the base station can be established reliably. The wireless communication terminal MN2 sets a normal handover procedure, that is, a terminal ID, a physical address, an ARQ setting value, an IP address, and a netmask (step T12). In step T13, a connection with the base station is established. It is determined whether or not it has been done. If the connection is not established, the handover procedure at step T12 is performed, and then it is determined whether or not the connection with the base station is established (step T14). When the connection with the base station AP1 can be established by the handover process, the radio communication terminal MN2 transmits a response message of the relay station determination message to the radio communication terminal MN1 (step T15).

  Thereafter, the operation is the same as the processing in the case of impersonating the wireless communication terminal MN1. If connection establishment fails, the process proceeds to step T16, a connection establishment failure message is notified to the wireless communication terminal MN1, and the operation is terminated. With the above processing, the connection can be established in any form.

  Next, the data packet will be described. Although the mechanism for transferring data to terminals outside the service area has been prepared by the above processing, in order for the wireless communication terminal MN1 to receive data by the application via the wireless communication terminal MN2 which is a relay station, the other side of the network It is necessary to receive the data without forcing the “opposite terminal” and the “base station” that is the transmission source of the wireless communication to perform processing for changing the address and route by transferring the data. The obstacle here is the IP address. When the address assigned to the IP layer is different from the address of the IP data frame of the flowing data, the OS discards the packet. To solve this problem, the IP data frame is encapsulated to conceal the data path change.

  The flow of data flows as shown in FIG. The upper diagram of FIG. 4 is a diagram illustrating the layers of the counter terminal CN1, the base station AP1, the relay station MN2, and the receiving terminal MN1, and how data actually flows through these layers. As shown in the figure, in the opposite terminal CN1, data flows through the application layer, the TCP / IP layer, the LLC layer, the MAC layer, and the physical layer. In the process of flowing from the application layer to the TCP / IP layer, the “data” is attached with a “TCP / IP layer header” as shown in FIG. In addition, a “MAC header layer” is added when the TCP / IP layer passes through the LLC layer to the MAC layer, and the state shown in FIG. Furthermore, when the MAC layer passes to the physical layer, the state shown in FIG. 4B is reached, and data flows in the state shown in FIG. 4B between the opposite terminal CN1 assumed to be a priority network and the base station AP1. When flowing through the base station AP1, the header is removed in reverse to the above, and the IP address and MAC address are analyzed, and then the base station AP reattaches the header and transmits the data to the wireless section.

Next, an operation of receiving data flowing from the opposite terminal CN1 through the base station AP1 to the relay station MN2 will be described.
1) Opposite terminal CN1
(D) → (c) → (b) → send to wired network 2) Base station AP1
Reception → (b) → (c) → (d) → (c) → (b) → (a) → Transmission to wireless section 3) Relay station MN2
Reception → (a) → (b) → (c) → (d) → (e) → (f) → (a) ′
Note that (a) ′ (not shown) is different from (a) and includes an encapsulation header.
3) Receiving terminal MN1
Reception → (a) '→ (f) → (e) → (d) → Data reception Note that the operation of the opposite receiving terminal MN1 is the reverse of transmission. Usually, an encapsulation header is not attached, but in this embodiment, an encapsulation header is attached.
4) Receiving terminal MN1
Transmission → (d) → (e) → (f) → (a) ′ → Transmission to wireless section 5) Relay station MN2
Reception → (a) ′ → (f) → (e) → (d) → (c) → (b) → (a) → Transmission 6) Base station AP1
Reception → (a) → (b) → (c) → (d) → (c) → (b) → Send to wired network 7) Opposite terminal CN1
Receive → (b) → (c) → (d) → Receive data

  Thereafter, in the base station AP1, the physical layer, MAC layer, LLC layer, TCP / IP layer, LLC layer, MAC layer, and physical layer flow. Thereafter, data flows in the relay station MN2 in the same manner as in the base station AP1. Further, in the receiving terminal MN1, data flows through the physical layer, the MAC layer, the LLC layer, the TCP / IP layer, and the application layer.

  Each of FIGS. 4A to 4F, which is the lower diagram of FIG. 4, is a diagram showing how the shape of data changes with the actual flow of data, and shows an example of a data frame configuration in the flow of data. ing. This will be described based on the data flow from the opposite terminal CN1 to the mobile station MN1. The data transmitted from the opposite terminal CN1 reaches the mobile station MN1 via the base station AP1 and the relay station MN2. At that time, data flowing through the Network cable flows in a frame configuration as shown in FIG. As shown in FIG. 4, it is assumed that the address of the opposite terminal CN1 is called a transmission source address and its value is A. On the other hand, the address on the mobile station MN1 side is B. The data flows through the network to the base station through the same route and the same data frame configuration as before the mobile station MN1 had the relay station MN2 relay the data. The base station AP1 also transmits wireless communication with the data frame configuration as it is. Here, the terminal that receives the data replaces the mobile station MN1 with the relay station MN2. The relay station MN2 has a network interface called address B in the procedure for becoming a relay station, and uses this network interface to receive up to the TCP / IP layer, loop back, and send data to the network interface at address D. Forward. At the time of this return, a header is added and encapsulated so that data is transmitted from address D to address C. Encapsulation corresponds to adding a new header and termination information to the frame shown in FIG. 4D, which is the original frame structure, as shown in FIG. 4E. Refers to creating a data frame with new parameters. The data frame (e) which becomes a new frame is attached to each header by the MAC layer and the physical layer and transmitted to the radio section.

  The mobile station MN1 that has received the data removes the header and receives it in the frame state of FIG. 4 (e) at the TCP / IP layer. If data is passed to the OS with this configuration, the OS is discarded in an attempt to pass data to the application using the network interface at address C. Therefore, the TCP / IP layer removes the encapsulation header and termination information part and passes the data to the OS.

  By performing the series of operations described above, communication can be continued even in a situation where the mobile station MN1 goes out of the communication area of the base station AP1. As for transmission, the transmission / reception function can be operated by performing encapsulation in the opposite direction.

  As described above, in the radio communication system according to the present embodiment, for a terminal moved out of service area from the communication area of the base station, it is possible to maintain communication with the base station using another terminal as a relay station by the above procedure. There is an advantage that the handover can be performed easily and reliably.

  The present invention can be applied to a communication network such as a mobile phone as well as a wireless LAN.

1 (a) to 1 (d) are schematic diagrams illustrating an operation relating to securing a communication connection in a wireless communication system according to an embodiment of the present invention. The figure which is a 1st example of operation | movement of the relay station by this Embodiment, Comprising: Operation | movement when the terminal used as a relay station is simply comprised, or operation | movement when the terminal used as a relay station once performs a handover operation | work It is. It is a figure which shows the system configuration example of the terminal by this Embodiment. It is a figure which shows the state of the data which flow through a network regarding various terminals, a base station, and a relay station. It is a flowchart figure which shows operation | movement of the terminal which is going to go out of service area by this Embodiment. It is an operation | movement flowchart of the terminal used as the relay station in the base station area by this Embodiment. It is a figure which shows the 1st prior art example of a hand-over. It is a figure which shows the 2nd prior art example of a handover. It is a figure which shows the 3rd prior art example of a hand-over, and is a figure which shows an example in case a base station has a function to perform data transfer by radio | wireless communication. It is a functional block diagram which shows the structural example of the mobile station by this Embodiment.

Explanation of symbols

A ... Wireless communication system, AP1 ... Base station, MN1, MN2 ... Terminal station, 1 ... Application, 2 ... Application requiring connection, 3 ... OS, 4 ... Driver, 5 ... Card I / F, 6 ... Firmware, 7 ... MAC 8 ... RF, 9 ... PHY, 10 ... application layer, 11 ... TCP / IP layer, 12 ... LLC layer, 13 ... MAC layer, 14 ... physical layer, 50 ... communication area.

Claims (15)

A base station,
A first mobile station in communication with the base station;
A wireless communication system having a second mobile station in a state capable of communicating with the base station via the first mobile station. A base station,
A first mobile station capable of communicating with the base station in the communication area of the base station;
A wireless communication system having a second mobile station in a state in which communication with the base station is possible via the first mobile station outside the communication area of the base station.   When moving out of the communication area of the base station, a handover process including a process for having surrounding terminals become relay stations with the base station is performed. Bureau.   The first mobile station according to claim 3, wherein the handover process includes a process of issuing a relief protocol to the surrounding terminals.   4. The first mobile station according to claim 3, wherein the surrounding terminal performs a process of impersonating the first mobile station by the handover process. 5.   The impersonating process includes a process of transmitting information necessary for the first mobile station to transmit / receive data to / from the base station instead of the second mobile station. 5. The first mobile station according to 5.   The impersonation process is that the first mobile station transmits / receives data to / from the base station instead of the second mobile station after returning to the base station after returning to the base station area. The 1st mobile station of Claim 5 including the process which transmits the information required for this. A mobile station capable of communicating with a base station,
A received signal detector for detecting the received signal;
And a notification unit that transmits and receives a notification signal for allowing a surrounding terminal to become a relay station to the base station in response to a decrease in signal strength by the reception signal detection unit. Bureau.   The mobile station according to claim 8, further comprising a database that stores first data related to relay station candidates that respond to a notification signal from the notification unit.   The notification unit transmits a relay station determination notification to the relay station candidate, and the relay station determination notification is associated with information related to communication, whereby the terminal serving as the relay station associates with the base station. The mobile station according to claim 8 or 9, wherein data transmission / reception with a base station can be performed on behalf of the mobile station without performing the step.   The communication according to any one of claims 1 to 10, wherein communication is performed between the first mobile station and the relay station and between the base station and the relay station using different frequencies or channels. The wireless communication system described. A handover method in a wireless communication system including a base station, a first mobile station in a state where it can communicate with the base station, and a second mobile station,
When the signal strength between the second mobile station and the base station becomes weak, the second mobile station mediates to the first mobile station so as to communicate with the base station. A handover method characterized by requesting A handover method in a wireless communication system including a base station, a first mobile station in a state where it can communicate with the base station, and a second mobile station,
A first step of detecting a signal strength between the second mobile station and the base station;
A second step of requesting the second mobile station to become a relay station toward the surroundings when the signal strength is weakened in the first step;
A third step of determining a relay station according to a response from a surrounding second mobile station;
And a fourth step of adjusting a frequency band or channel used with the determined first mobile station as the relay station.   The method according to claim 13, further comprising a fifth step of transmitting information necessary for the first mobile station to transmit / receive data to / from the base station instead of the second mobile station.   14. The fifth step according to claim 13, further comprising a fifth step in which the second mobile station transmits old terminal information at the time of connection with the base station necessary for handover to the first mobile station. the method of.

Images