WO2008065823A1 - Station de base et système de communication sans fil - Google Patents
Station de base et système de communication sans fil Download PDFInfo
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- WO2008065823A1 WO2008065823A1 PCT/JP2007/070184 JP2007070184W WO2008065823A1 WO 2008065823 A1 WO2008065823 A1 WO 2008065823A1 JP 2007070184 W JP2007070184 W JP 2007070184W WO 2008065823 A1 WO2008065823 A1 WO 2008065823A1
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- base station
- packet
- inter
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- transfer
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/02—Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
Definitions
- the present invention relates to a handover for switching a base station with which a mobile device is communicating in a wireless communication system.
- the present invention relates to a user data packet addressed to a mobile device that has performed a handover, and is transmitted to the mobile device.
- the present invention relates to a base station and a wireless communication system that reduce a processing delay during execution of handover in which user data packets that have not been transferred are transferred from a handover source to a handover destination.
- a handover method in a conventional wireless communication system will be described.
- a mobile device communicates with a base station while moving between communication areas called cells created by a plurality of base stations. Then, when the mobile station reaches the vicinity of the cell boundary and the radio communication quality deteriorates and it is difficult to continue communication with the base station, handover to the base station with better radio communication quality is performed.
- the data packet that remains in the handover source base station without being transmitted to the mobile station before the handover is performed can be transmitted.
- the handover destination base station transmits the last data packet (hereinafter referred to as the final base packet) transferred from the handover source base station. (Referred to as inter-station transfer packet), and after transmitting this packet to the mobile station, it starts transmitting data packets received directly from the upper node.
- the handover destination base station As a method for the handover destination base station to identify the final inter-base station transfer packet, information (for example, given to each data packet) that the handover source base station specifies the final inter-base station transfer packet in the control message. (Sequence number) is stored and notified to the handover destination base station (for example, Patent Document 1 below).
- this method handles control messages.
- the information for specifying the final inter-base station transfer packet using a notification packet instead of a control message is a problem to solve this problem. Is disclosed to the handover destination base station (for example, Patent Document 2 below).
- Patent Document 1 Japanese Patent Laid-Open No. 09-186704
- Patent Document 2 Special Table 2001-500675
- control data exchanged between the devices and user terminals such as mobile devices are transmitted and received to control the operation of the devices.
- Different user data is handled separately and handled by different processing systems.
- the base station determines whether it is control data or user data, and distributes the processing system according to the data type.
- the information for specifying the final inter-base station transfer packet can be used so that the final inter-base station transfer packet can be identified by the handover destination base station.
- a notification packet for storing and notifying is newly generated and transmitted to the handover destination base station.
- the handover destination base station in addition to determining whether the received data packet is control data or user data, the handover destination base station also determines whether it is user data or notification data (notification packet). There is a need to do
- the handover source base station needs to add a function of newly generating notification data, storing it in a notification packet, and transmitting it. Since the destination base station needs to add a function for identifying the notification data and distinguishing it from the user data, there is a problem in that the circuit scale of the base station is increased and the processing delay is increased.
- the present invention has been made in view of the above, and in handover processing in which an untransmitted data packet addressed to a mobile device that has performed handover is transferred from the handover source base station to the handover destination base station.
- handover processing in which an untransmitted data packet addressed to a mobile device that has performed handover is transferred from the handover source base station to the handover destination base station.
- the present invention provides a base station for transmitting untransmitted data packets addressed to a mobile device from a handover source base station when a mobile device that has performed a handover is accommodated.
- a base station that receives as an inter-station transfer packet, a packet holding unit for holding a data packet to which a sequence number is assigned and an inter-base station transfer packet, and the packet holding unit holds an inter-base station transfer packet.
- the packet reading means for reading all the inter-base station transfer packets in the order of the sequence numbers, and then reading the data packets in the order of reception, and the inter-base station transfer packets and data packets read by the packet reading means.
- Packet transmitting means for transmitting the packet to the destination mobile station, and the packet reading means It is characterized in that whether or not all inter-base station transfer packets have been read is determined based on the sequence number.
- the handover destination base station compares the sequence number assigned to the first data packet directly received from the base station controller with the sequence number assigned to the inter-base station transfer packet.
- the final inter-base station transfer packet is identified and the final inter-base station transfer packet is identified, it is determined that all base station transfer packets have been transmitted to the mobile station and received directly from the base station controller.
- the data packet transferred between base stations is a notification packet (a packet storing information for identifying the final inter-base station transfer packet).
- FIG. 1 is a diagram showing a configuration example of a radio access network including a base station that is effective in the present invention.
- FIG. 2 is a diagram showing a configuration example and a data transmission path of a base station control device, a base station, and a mobile device constituting the radio access network of the first embodiment.
- FIG. 3 is a diagram showing an example of an internal configuration of a data receiving unit constituting a base station.
- FIG. 4 is a sequence diagram showing an example of a handover operation.
- Figure 5-1 is a diagram for explaining the data packet transmission operation during handover.
- Figure 5-2 is a diagram for explaining the data packet transmission operation during handover.
- Fig. 5-3 is a diagram for explaining the data packet transmission operation during handover.
- Fig. 5-4 is a diagram for explaining the data packet transmission operation during handover.
- Fig. 5-5 is a diagram for explaining the data packet transmission operation during handover.
- Fig. 5-6 is a diagram for explaining the data packet transmission operation during handover.
- FIG. 6 is a diagram showing a configuration example and a data transmission path of each device constituting the radio access network of the second embodiment.
- FIG. 7-1 is a diagram for explaining a data packet transmission operation at the time of handover in the radio access network of the second embodiment.
- FIG. 7-2 is a diagram for explaining a data packet transmission operation at the time of handover in the radio access network according to the second embodiment.
- FIG. 8 is a diagram showing a configuration example and a data transmission path of each device constituting the radio access network of the third embodiment.
- FIG. 9-1 is a diagram for explaining a data packet transmission operation at the time of handover in the radio access network of the third embodiment.
- FIG. 9-2 is a diagram for explaining a data packet transmission operation at the time of handover in the radio access network according to the third embodiment.
- FIG. 10 is a diagram showing a configuration example and a data transmission path of each device constituting the radio access network of the fourth embodiment.
- FIG. 11 is a diagram showing an internal configuration example of a data receiving unit constituting the base station of the fourth embodiment.
- FIG. 1 is a diagram showing an example of the configuration of a radio access network (radio communication system) equipped with a base station according to the present invention.
- 1 is the connected upper network (shown Base station controller that distributes data received from each base station in the radio access network, 2;! To 2-n are data received from the base station controller 1 via the fountain transmission path Is transmitted to the wireless transmission path, and the base station 3 determines whether or not handover is necessary based on the wireless quality information received from the mobile station, 3 is wirelessly transmitted between the base stations 2— ;! to 2-n Mobile stations that communicate via a route, 4 1 to 4 n are cells formed as communication areas for the base station 2—;! To 2— n to communicate with the mobile device 3 via a wireless transmission path.
- Reference numeral 5 denotes a wired transmission path that connects the base station control device 1 and each base station 2- ;! to 2-n controlled by the base station control device 1.
- FIG. 2 is a diagram showing a configuration example and a data transmission path of the base station controller, base station, and mobile device configuring the radio access network shown in FIG. 1, and the dotted line in the figure is the one after the handover It shows a data transmission path.
- the base station controller 1 accommodates a user data packet (hereinafter referred to as a data packet) received from the network in its destination mobile station! /
- the data transmission unit 11 and the data transmission unit 11 for distribution to the network and the path switching control unit 12 for switching the transmission path (delivery destination) of the data packet are provided.
- Each base station receives and holds the data packet transmitted from base station controller 1 or the data packet transferred from another base station.
- the data receiving unit corresponds to the packet holding unit
- the reading control unit corresponds to the packet reading unit.
- the wireless transmission unit corresponds to a packet transmission unit.
- the mobile device 3 includes a radio reception unit 31 that receives a data packet transmitted from a base station, and a handover control unit 32 that controls a handover operation.
- the reading control unit of the base station holds data packets (hereinafter referred to as inter-base station transfer packets) transferred from other base stations by the data receiving unit! /, N! /
- the data receiver reads the data packets in the same order as the data packets were received.
- the inter-base station transfer packet transferred from another base station is held, the inter-base station transfer packet is read first, and after all the inter-base station transfer packets are read, the base station controller Read the data packet received directly from 1.
- FIG. 3 is a diagram showing an example of the internal configuration of the data receiving units (data receiving units 21-1 and 21-2) constituting the base station.
- reference numeral 211 denotes a buffer for temporarily storing received data packets (data packets directly received from the base station controller 1 and inter-base station transfer packets transferred from other base stations).
- Reference numeral 212 denotes a sequence number management unit that stores and manages the sequence number assigned to the user data together with the storage position in the notifier 211 of the received data packet.
- the base station control device 1 communicates data packets addressed to the mobile device 3 received from the higher level network among the base stations 2—;! To 2-n connected via the wired transmission path 5. Data is transmitted from the data transmission unit 11 to the base station 2-1 that is in use. At this time, if there is another mobile device connected to the base station 2 1 other than the mobile device 3, data packets addressed to other mobile devices are also transmitted from the base station controller 1 to the base station 2. Send to —1 in the same way.
- a sequence number is given to the data packet transmitted to the base station 21 according to the transmission order. In the following description, it is assumed that the sequence number is assigned as 0 to 63.
- the mobile station 3 communicates before executing the handover! /! To the base station 2-1! /, And thus the data receiving unit 21-1 receives from the base station controller 1
- the data packet addressed to mobile station 3 is temporarily stored in the internal buffer 211 and attached to the data packet.
- the storage location of the user packet in the buffer 211 and the sequence number are combined and registered in the sequence number management unit 212.
- Read control unit 2
- Receiver 21 Reads out from buffer 211 and transmits wirelessly 2
- the wireless transmission unit 23-1 converts the user data received from the read control unit 22-1, into a signal for wireless transmission, and transmits the signal to the mobile device 3 under control (in the cell 41) via the wireless transmission path.
- wireless reception unit 31 when wireless reception unit 31 receives wireless transmission data from base station 2-1, it transmits reception quality information (for example, reception power level information) of the received signal to handover control unit 32. To do.
- the handover controller 32 measures information necessary for determining whether or not handover is necessary from the reception quality information received from the wireless receiver 31. Here, for example, reception quality information received within a predetermined period is averaged. Then, the wireless quality information including the measurement result is stored in a control message and notified to the base station 21.
- the control message is notified to the handover control unit 24 1 of the base station 2-1 via a radio transmission unit (not shown) of the mobile device 3 and a radio reception unit (not shown) of the base station 2-1. .
- control messages notified from the base stations 2 1 and 2-2 to the base station controller 1 are also notified via a data transmitter in the base station and a data receiver in the base station controller not shown.
- the handover control unit 32 also includes information on the quality (for example, received power level) of the control signal received from the base station other than the base station 2-1 that is transmitting data, if necessary. It is included in the information and notified to the base station 21. As a result, the base station 2-1 can specify the handover destination base station at the time of executing the handover.
- the quality for example, received power level
- the handover controller 24-1 determines whether or not handover is necessary based on the radio quality information stored in the control message received from the mobile device 3, and reads the determination result. Notify the controller 22 1.
- a handover request indicating the start of the handover process is sent to the base station 2-2 as the handover destination base station.
- the handover control unit 24-1 For example, the handover destination base station is determined using information on the received signal quality from base stations other than the base station 21 included in the wireless quality information.
- the handover controller 24-1 sends a handover instruction for instructing the mobile device 3 to start the handover process.
- the read control unit 22-1 sends the data packet read from the data reception unit 21-1 to the radio transmission unit 2 3 1 Continue operation.
- the handover target data packet packet addressed to mobile station 3 that performs handover
- the packet transfer unit 25-1 sends the data packet received from the read control unit 22-1 via the inter-base station transfer path 6 to the base station 2-2 as the handover destination base station as an inter-base station transfer packet.
- the inter-base station transfer path 6 may be realized by connecting the base stations directly with a wired transmission path, or via the base station control apparatus 1 using the fountain transmission path 5 shown in FIG. It may be realized.
- the data transmission unit 11 Continues data transmission to base station 21.
- the route switching control unit 12 sends the data packet of the user targeted for handover (in this example, the data packet addressed to the mobile station 3) to the base station 2-2.
- the data transmission destination packet transmission path.
- the base station 2-2 which is the handover destination base station
- the data receiver 21-2 receives the inter-base station transfer packet received from the handover source base station 2-1 and the base station controller.
- Data packet received directly from 1 Is received and stored by storing the received packet in the internal buffer 211.
- each packet (a data packet received directly from the base station controller 1 and a data packet received as an inter-base station transfer packet) depends on the processing time when transferring the packet between the base stations.
- the order stored in the buffer 211 is not necessarily the same as the order transmitted by the base station controller 1. Therefore, the read control unit 222 operates so as to read the inter-base station transfer packet first in order to prevent the data packet order from being reversed. Specifically, based on the sequence number assigned to the inter-base station transfer packet and the data packet, it is determined whether or not all the inter-base station transfer packets have been read. Then, reading of the data packet received directly from the base station controller 1 is started.
- the reading control unit determines whether or not the reading of all inter-base station transfer packets has been completed.
- Read control unit 22-2 refers to the information managed by sequence number management unit 212, and the sequence number assigned to the first data packet directly received from base station control device 1 and the inter-base station transfer packet Compare the sequence number assigned to. As a result of the comparison, when the sequence number immediately before the sequence number assigned to the first data packet directly received from the base station controller 1 is detected, this inter-base station transfer packet is transmitted between the last base stations. Judged as a forwarded packet. When the reading control unit 22-2 passes the inter-base station transfer packet determined to be the final inter-base station transfer packet to the wireless transmission unit 23-2, it recognizes that reading of all the inter-base station transfer packets has been completed. Then, the data packet read operation directly received from the base station controller 1 is started.
- base station 2 2 (handover destination base station) is given a sequence number one prior to the sequence number given to the first data packet received directly from base station controller 1
- the inter-base-station transfer packet is transmitted as the final inter-base-station transfer packet to the destination mobile station 3, and thereafter, the received data packet is directly received from the base station controller 1 and the stored data packet is transmitted to the base station controller 1 Transmit to mobile unit 3 in the same order as sent from (according to the order received).
- the reading control unit 22-2 is used to store the data stored in the data receiving unit 21-2.
- the address area of the buffer 211 to be stored is divided or a physically separate memory is provided.
- the storage area in the data receiving unit 21-2 may be separated in advance, or the data packet may be identified by adding a flag indicating the transmission source device to the stored data. good.
- FIG. 4 is a sequence diagram showing an example of the handover operation.
- Fig. 5—;! To 5-6 are diagrams for explaining the data packet transmission operation at the time of handover.
- solid arrows indicate transmission / reception of control messages for controlling the operation of each device, and white arrows indicate transmission / reception of user data.
- the solid line arrow indicates the data transmission path that is valid at that time
- the dotted line arrow indicates the data transmission path that is invalid at that time.
- the switching of the dotted line represents the switching of the data transmission path before and after the handover.
- the base station controller 1 and the mobile device 3 transmit and receive user data via the base station 2-1, and then the mobile device 3 moves toward the cell 42 managed by the base station 2-2. Move.
- the mobile device 3 transmits wireless quality information indicating that to the base station 2-1 (step S11).
- the handover control unit 24-1 decides to execute the handover (step S12), stops the user data transmission to the mobile station 3, and — Send a handover request message to 2 (step S 13).
- Figure 5 shows an example of the state of data packets sent from the base station controller 1 to the mobile station 3 up to this point.
- the base station 2— 1 indicates that transmission to mobile station 3 has been completed.
- the base station 2-2 When the handover control unit 24-2 recognizes that the handover request message has been received, the base station 2-2 returns a handover request response message to the base station 2-1 as a response (step S14).
- the handover control unit 24-1 of the base station 2-1 includes the handover request response message When it is determined that handover has been performed, it instructs the readout control unit 22-1 to start the transfer between base stations of data packets that have not been transmitted to mobile station 3, and transfer between base stations. Is started (step S15). Furthermore, in parallel with this, the handover control unit 24-1 sends a handover instruction message to the mobile device 3 (step S16).
- the read control unit 22-1 that has started the transfer between base stations reads the data packet addressed to the mobile device 3 remaining in the data reception unit 21-1 and sends it to the packet transfer unit 25-1.
- the knot transfer unit 25-1 sends the data packet received from the read control unit 22-1 to the base station 2-2 as an inter-base station transfer packet.
- the handover control unit 32 of the mobile device 3 that has received the handover instruction message instructs the wireless reception unit 31 to switch the path for wireless transmission from the base station 2-1 to the base station 2-2.
- the handover control unit 32 sends a handover instruction response to the base station 2-2 to notify that (Step S18).
- Figure 5-2 shows that data packets with sequence numbers # 57 to # 59 that have not been transmitted to mobile station 3 when base station 2-1 determines that a handover has been performed are transferred between base stations.
- the base station controller 1 continues to transmit data packets addressed to the mobile station 3 to the base station 2-1.
- the handover control unit 24-2 can transmit wireless data to the mobile device 3 in response to the handover instruction response received from the mobile device 3.
- the inter-base station transfer packet held in the buffer 211 in the data receiving unit 21-2 is transmitted to the mobile device 3 in the order of the sequence number.
- the data packet transfer between the base station 2-1 and the base station 2-2 is performed by the handover control unit 24-2 of the base station 2-2 in step S18.
- a route switching request message is transmitted to the base station controller 1 (step S19), and further, from the route switching controller 12 of the base station controller 1 that has received this route switching request message.
- the data transmission unit 11 that has been instructed to switch the data transmission path from the base station 2-1 to the base station 2-2 switches the transmission path (step S20).
- Figure 5-3 shows that the base station 2-2 starts transmission to the mobile station 3 in order from the first inter-base station transfer packet (data packet with sequence number # 57), and the final inter-base station transfer packet
- the processing of step S20 above is completed and the transmission path is switched, and the base station controller 1 starts from the data packet with the sequence number # 2 to the base station 2— It shows how direct transmission to 2 starts.
- step S20 For a while after step S20 is executed and the transmission path is switched, the data reception unit 21-2 of the base station 2-2 receives the inter-base station transfer packet and the base station controller 1 directly. Both data packets are stored in the order received.
- the order stored at this time is the same as the order transmitted by the base station control device 1 (that is, the sequence number assigned to the data packet) due to the influence of the processing time when transferring packets between base stations. It does not always become.
- Figure 5-4 shows that the received data packets at base stations 2-2 arrived in the order of sequence numbers # 2, # 63, # 0, # 3, # 4, # 1.
- the state stored in the data receiving unit 21-2 is shown.
- the sequence number assigned to the first data packet directly received by the handover destination base station directly from the base station controller and the sequence assigned to the inter-base station transfer packet The base station controller determines that all the base station transfer packets have been transmitted to the mobile station when the final inter base station transfer packet is identified by comparing the numbers and the final inter base station transfer packet is identified.
- the system is configured to start transmission of data packets received directly from the mobile station.
- the data packet transferred between base stations, which is a process executed in the handover destination base station, which is necessary in the conventional handover method is transmitted as a notification packet (information for specifying the final inter-base station transfer packet). Therefore, it is possible to reduce processing delay during handover execution while suppressing an increase in circuit scale.
- FIG. 6 is a diagram showing a configuration example and a data transmission path of each device constituting the radio access network according to the second embodiment of the present invention, and a dotted line in the figure shows a data transmission path after the handover. . 6 that perform the same operation as each device or component (see FIG. 2) constituting the radio access network of the first embodiment described above in FIG. .
- FIGS. 7-1 and 7-2 are diagrams for explaining the data packet transmission operation during handover execution in the radio access network of the second embodiment.
- the base station control device la of the second embodiment is obtained by replacing the data transmission unit 11 of the base station control device 11 of the first embodiment with a data transmission unit 11a.
- Base stations 2a-1 and 2a-2 are obtained by replacing the read control units of base stations 2-1 and 2-2 of Embodiment 1 with read control units 22a-1 and 22a-2.
- the configuration of the mobile device 3 is the same as that shown in the first embodiment. [0047] The operation of each unit when the mobile station executes handover in the radio access network of the second embodiment will be described with reference to Figs. 6, 7-1, and 7-2. As in the case of the first embodiment, the mobile station 3 accommodated in the base station 2-1 (cell 4 1) in the radio access network shown in FIG. The handover operation when moving to cell 4 2) is explained.
- the data transmission unit 11a of the base station controller la is the base station 2a-1 until the path switching control unit 12 receives a path switching request message from the base station 2a-2 that is the handover destination base station.
- the path switching control unit 12 receives a path switching request message from the base station 2a-2 that is the handover destination base station.
- base station 2a 1 which is a handover source base station decides to perform a handover to base station 2a-2 based on the radio quality information received from mobile station 3
- base stations 2a-1 and 2a-2 and mobile stations 3 performs the handover process according to the procedure shown in the first embodiment (see Fig. 4).
- the path switching control unit 12 switches the transmission path accordingly, the data transmission unit 11a at that time Finally, the same data packet that was transmitted to the base station 2a 1 is first transmitted to the base station 2a-2 that is the handover destination base station.
- FIGS. 7-1 and 7-2 show the state of data packet transfer at this time.
- Figure 7-1 shows that when the base station 2a-1 decides to perform handover, the data packets whose sequence number is # 57 or later that has not been transmitted to the mobile station 3 are transferred between base stations.
- the control device la continues to transmit data packets addressed to the mobile device 3 to the base station 2a1.
- Figure 7-2 also shows that base station 2a-2 starts transmission to mobile station 3 in order starting with the first inter-base station transfer packet (data packet with sequence number # 57).
- the base station 2a-1 determines that the handover is performed and the transmission path switching is executed by the base station controller la
- the base station 2a-2 as the handover destination base station
- the inter-base station transfer packet from the base station 2a-1 and the data packet received directly from the base station controller la are stored in the data receiving unit 21-2.
- the order stored at this time is the same as the order transmitted by the base station controller la (that is, the order of the sequence numbers given to the data packets) due to the influence of the processing time when transferring packets between base stations. Not necessarily.
- the read control unit 22a-2 operates to read the inter-base station transfer packet first in order to prevent the data packet from being reversed in order, and based on the sequence number assigned to the data packet, When recognizing that reading of the transfer packet is complete, reading of the data packet received directly from the base station controller la starts.
- the read control unit 22a-2 is managed by the sequence number management unit 212 of the data reception unit 211-2.
- the sequence number given to the first data packet received directly from the base station controller la that is, the same data packet that was last transmitted to the handover source base station 2a-1
- the sequence number assigned to the inter-base station transfer packet is determined to be the final inter-base station transfer packet.
- the read control unit 22a-2 recognizes that all the inter-base station transfer packets have been read. Then, the data packet read operation directly received from the base station controller la starts. At this time, the data packet first received from the base station controller la with the sequence number # 1 is discarded when read from the buffer 211, and the data packet with the sequence number # 2 or later is received from the base station controller la. The data are read out in the order in which they are sent, and passed to the wireless transmitter 23-2.
- the wireless transmission unit 23-2 transmits the data packet received from the read control unit 22a-2 to the mobile device 3.
- the sequence number assigned to the first data packet directly received by the handover destination base station directly from the base station controller and the sequence assigned to the inter-base station transfer packet is identified as the final inter-base station transfer packet.
- the final inter-base station transfer packet it is determined that all base station transfer packets have been transmitted to the mobile station, and transmission of data packets received directly from the base station controller to the mobile station is started. It was configured to work.
- the data packet transferred between base stations, which is a process executed in the handover destination base station, which is necessary in the conventional handover method becomes a notification packet (information for identifying the final inter-base station transfer packet). Therefore, it is possible to reduce the processing delay at the time of executing the handover while suppressing an increase in circuit scale.
- FIG. 8 is a diagram showing a configuration example and a data transmission path of each device constituting the radio access network according to the third embodiment of the present invention, and a dotted line in the figure shows a data transmission path after the handover. .
- FIGS. 9A and 9B are diagrams for explaining the data packet transmission operation during handover execution in the radio access network of the third embodiment.
- the base station controller lb of the third embodiment is obtained by replacing the data transmitter 11 of the base station controller 11 of the first embodiment with a data transmitter l ib. .
- the base stations 2b 1 and 2b-2 are obtained by replacing the read control units 22 1 and 22-2 of the base stations 2 1 and 2-2 of the first embodiment with read control units 22b-1 and 22b-2. It is.
- the configuration of the mobile device 3 is the same as that shown in the first embodiment.
- the data transmission unit l ib of the base station controller lb receives a route switching request message from the base station 2b 1 which is the handover destination base station of the route switching control unit 12 Data transmission to base station 2b-1 until When base station 2b-l, which is the handover source base station, decides to perform a handover to base station 2b-2 based on the radio quality information received from mobile station 3, it moves with base stations 2b-1 and 2b-2.
- Unit 3 executes the handover process according to the procedure shown in the first embodiment (see FIG. 4).
- the data transmission unit l ib first transmits the data packet that was last transmitted to the base station 2b-1 at that time. Are retransmitted a predetermined number of times.
- the path switching control unit 12 switches the transmission path. Then, the data transmission unit l ib starts data packet transmission to the base station 2b-2 that is the handover destination base station.
- FIGS. 9-1 and 9-2 show the state of data packet transfer at this time.
- Figure 9-1 shows that when the base station 2b-1 decides to execute the handover, the data packets whose sequence number is # 57 or later that has not been transmitted to the mobile station 3 are transferred between base stations.
- the control device lb continues to transmit the data packet addressed to the mobile station 3 to the base station 2b 1 and receives the path switching request message, the data packet (sequence number # 1) that was last transmitted to the base station 2b 1 is received.
- the figure shows how a predetermined number of data packets are duplicated and transmitted (retransmitted) to base station 2b-1.
- Figure 9 2 shows the sequence in which base station 2b 2 starts transmission to mobile station 3 in order from the first inter-base station transfer packet (data packet with sequence number # 57), and then becomes the final inter-base station transfer packet. After the data packet with the number # 1 is transferred from the base station 2b 1, the transmission path is switched, and the base station controller lb starts direct transmission from the data packet with the sequence number # 2 to the base station 2b-2. I'll show you how.
- the base station 2b-2 that is the handover destination base station is the base station 2b 1
- the inter-base station transfer packet from the base station and the data packet received directly from the base station controller lb are stored in the data receiver 21-2.
- the order stored at this time is the same as the order transmitted by the base station controller lb (that is, the sequence number assigned to the data packet) due to the effect of the processing time when transferring packets between base stations. Not necessarily. For this reason, the read controller 22b-2 prevents the data packets from being reversed in order.
- the base station controller lb recognizes that reading of all inter-base station transfer packets has been completed based on the sequence number assigned to the data packet, it reads from the base station controller lb. Start reading data packets received directly.
- the read control unit 22b-2 only needs to read one of the final inter-base station transfer packets.
- the read control unit 22b-2 is managed by the sequence number management unit 212 of the data reception unit 211-2. Check the sequence number assigned to the inter-base station transfer packet by referring to the information. If there are a plurality of inter-base station transfer packets with the same sequence number as a result of the confirmation, it is determined that the packet with the same sequence number is the final inter-base station transfer packet.
- the reading control unit 22b-2 passes the inter-base station transfer packet determined to be the final inter-base station transfer packet to the wireless transmission unit 23-2, reading of all the inter-base station transfer packets that need to be read is completed. Recognize.
- the base station controller retransmits the last data packet transmitted to the handover source base station a predetermined number of times, and the read control unit in the handover destination base station performs the data reception unit. If the same sequence number is detected in multiple inter-base station transfer packets with reference to the sequence number assigned to the inter-base station transfer packet managed in (5), this inter-base station transfer packet is designated as the final inter-base station transfer packet. When the final inter-base station transfer packet is identified, it is determined that all the base station transfer packets that need to be transmitted have been transmitted to the mobile station and received directly from the base station controller. The data packet is configured to operate so as to start transmission to the mobile device.
- the handover destination base station which is necessary in the conventional handover method, Since it is not necessary to identify whether or not the data packet transferred between base stations is a notification packet (a packet storing information for specifying the final inter-base station transfer packet), which is a process to be executed.
- a notification packet a packet storing information for specifying the final inter-base station transfer packet
- the handover source base station transmits a plurality of final inter-base station transfer packets
- the final inter-base station transfer packet is lost during the transfer, and the data packet received directly from the base station controller Can be prevented from being unable to determine the transmission start timing.
- FIG. 10 is a diagram showing a configuration example and data transmission path of each device constituting the radio access network according to the fourth embodiment of the present invention, and the dotted line in the figure shows the data transmission path after the handover. . 10 that perform the same operation as each device or component (see FIG. 2) constituting the radio access network of the first embodiment described above in FIG. .
- the base stations of Embodiment 4 are the data receiving units of base stations 2-1 and 2-2 of Embodiment 1.
- 21—1, 21—2 and read controller 22—1, 22—2 are replaced with data receivers 21c—1, 21 c—2 and read controller 22c—1, 22c—2, respectively.
- the configurations of base station controller 1 and mobile device 3 are the same as those shown in the first embodiment.
- FIG. 11 is a diagram showing an internal configuration example of the data receiving units (data receiving units 21c-1 and 21c-2) constituting the base station of the fourth embodiment.
- This data receiving unit has a configuration in which a timer management unit 213 is added to the data receiving unit of the first embodiment shown in FIG. Since other configurations are the same as those of the data receiving unit of the first embodiment, the same reference numerals are given and description thereof is omitted.
- the timer management unit 253 starts timing from the arrival time of the first data packet received directly from the base station controller 1, and continues timing until the inter-base station transfer packet is received. Manage the timer so that it expires when it expires. The timer is reset every time a transfer packet between base stations is received.
- Timings may be of different lengths as long as they need not be the same.
- the operation of each part when the mobile station executes handover in the radio access network of the fourth embodiment will be described using FIG. 10 and FIG.
- the mobile station 3 accommodated in the base station 2-1 (cell 4 1) in the radio access network shown in FIG. 1 is subordinate to the base station 2-2 ( The handover operation when moving to cell 4 2) is explained.
- the data transmission unit 1 1 c of the base station controller lc continues to transmit data to the base station 2 c 1 until the path switching control unit 12 receives a path switching request message from the base station 2 c 1.
- the base station 2c1 which is the handover source base station, decides to execute the handover to the base station 2a-2
- the base stations 2c-1 and 2c-2 and the mobile station 3 executes the handover process according to the procedure shown in the first embodiment (see FIG. 4).
- the base station 2c-2 that is the handover destination base station receives the inter-base station transfer packet transferred from the base station 2c 1 by the receiving unit 21c-2.
- the data packet directly transmitted from the base station controller lb is received, and the received packet is stored in the internal buffer 211.
- the data reception unit 21c-2 stores the sequence number of the data packet received by the sequence number management unit 212 together with the storage position in the buffer 211, and the timer management unit 253 further stores the base station controller 1
- timer timing starts. This timing continues until the next inter-base station transfer packet is received or until a predetermined time has elapsed, and when the predetermined time has elapsed (when the timer has expired), the timing ends. If the next inter-base station transfer packet is received before the predetermined time has elapsed, the timer is initialized.
- the time is measured until the next inter-base station transfer packet is received or until a predetermined time elapses, and then the same operation is continued until the timer expires.
- the order in which the data packets are stored in the data receiving unit 21c-2 is the order (sequence) transmitted by the base station control device 1 due to the influence of the processing time when the packets are transferred between the base stations. It is not always the same as (in numerical order).
- the read control unit 22c-2 operates to read the inter-base station transfer packet first in order to prevent the data packets from being reversed in order, and based on the sequence numbers assigned to the data packets, When recognizing that reading of the transfer packet is completed, reading of the data packet received directly from the base station controller 1 is started.
- the read control unit 22c-2 refers to the information managed by the sequence number management unit 212, and receives the sequence attached to the first data packet directly received from the base station control device 1. The number is compared with the sequence number assigned to the inter-base station transfer packet. As a result of the comparison, when a sequence number immediately before the sequence number assigned to the first data packet directly received from the base station controller 1 is detected, this inter-base station transfer packet is transmitted between the last base stations. Judged as a transfer packet. When the inter-base station transfer packet determined to be the final inter-base station transfer packet is passed to the wireless transmission unit 232, the read control unit 22c-2 recognizes that all the inter-base station transfer packets have been read. Then, the read operation of the data packet directly received from the base station control device 1 is started.
- the read control unit 22c-2 periodically monitors the state of the timer managed by the timer management unit 253. As a result of monitoring, if it is detected that the predetermined time has passed without receiving the inter-base station transfer packet (timer has expired), it is determined that the reading of all inter-base station transfer packets has been completed. Operates to start transmitting data packets received directly from station controller 1. By operating in this way, for example, the final inter-base station transfer packet is lost, and the transmission start timing of the data packet received directly from the base station controller 1 cannot be determined by the reception of the final inter-base station transfer packet. Even in this case, it is possible to start transmission of the data packet received directly from the base station controller 1.
- the handover destination base station receives the first data directly received by the handover destination base station from the base station control apparatus in the same manner as the handover destination base station of the first embodiment described above. Sequence number given to packet and transfer between base stations Based on the result of comparing the sequence numbers assigned to the transmitted packet! /, It is determined whether or not to start transmitting the data packet received directly from the base station controller to the mobile station. However, whether or not the inter-base station transfer packet was received within a predetermined time since the first data packet was directly received from the base station controller, and the next time within the predetermined time after receiving the inter-base station transfer packet.
- the handover destination base station does not have a data packet to be transferred from the handover source base station! /, Even when there is a data packet transmission start timing directly received from the base station controller Can be determined.
- the power S, the second embodiment, or the operation when the timer management unit is added to the data receiving unit included in the base station of the first embodiment is described.
- the timer management unit is added to the data reception unit provided in the base station of 3, and when the timer expiration is detected, it is also received directly from the base station control device. You may make it start transmission of a data packet.
- Embodiments 1 to 4 described above the operation example in which the base station determines whether or not the handover execution is necessary based on the radio quality information received from the mobile device has been described.
- the present invention can be applied even to a configuration in which a determination function is provided not in a base station but in a base station controller that is an upper node thereof, and when the handover execution is determined, the base station controller instructs the base station to execute a handover. is there.
- the base station according to the present invention is useful for radio communication for transmitting data packets, and in particular, when a handover occurs, the handover source base station performs handover. It is suitable for a base station of a wireless communication system that transfers user data packets addressed to a mobile device to a node base station.
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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EP07829918A EP2088793A4 (en) | 2006-12-01 | 2007-10-16 | BASIC STATION AND WIRELESS COMMUNICATION SYSTEM |
US12/516,990 US20100098024A1 (en) | 2006-12-01 | 2007-10-16 | Base station and wireless communication system |
JP2008546910A JP4726960B2 (ja) | 2006-12-01 | 2007-10-16 | 基地局および無線通信システム |
Applications Claiming Priority (2)
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JP2006-325819 | 2006-12-01 | ||
JP2006325819 | 2006-12-01 |
Publications (1)
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WO2008065823A1 true WO2008065823A1 (fr) | 2008-06-05 |
Family
ID=39467622
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/JP2007/070184 WO2008065823A1 (fr) | 2006-12-01 | 2007-10-16 | Station de base et système de communication sans fil |
Country Status (5)
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US (1) | US20100098024A1 (ja) |
EP (1) | EP2088793A4 (ja) |
JP (1) | JP4726960B2 (ja) |
CN (1) | CN101548563A (ja) |
WO (1) | WO2008065823A1 (ja) |
Cited By (2)
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JP2011229025A (ja) * | 2010-04-21 | 2011-11-10 | Ntt Docomo Inc | 移動通信システム、ネットワーク装置及び移動通信方法 |
JP2015119281A (ja) * | 2013-12-17 | 2015-06-25 | 富士通株式会社 | 無線通信装置および基地局装置内のハンドオーバ制御方法 |
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US8842631B2 (en) * | 2005-11-30 | 2014-09-23 | Qualcomm Incorporated | Data state transition during handoff |
US8830950B2 (en) | 2007-06-18 | 2014-09-09 | Qualcomm Incorporated | Method and apparatus for PDCP reordering at handoff |
CN102437887A (zh) * | 2011-10-18 | 2012-05-02 | 大唐移动通信设备有限公司 | 一种监听监测设备及其应用方法 |
DE112013007287T5 (de) * | 2013-07-30 | 2016-04-28 | Mitsubishi Electric Corporation | Datenverarbeitungsvorrichtung, Datenkommunikationsvorrichtung, Kommunikationssystem, Datenverarbeitungsverfahren, Datenkommunikationsverfahren und Programm |
KR102460350B1 (ko) * | 2015-11-06 | 2022-10-28 | 삼성전자주식회사 | 통신 시스템에서 데이터 송수신 방법 및 장치 |
US10178512B2 (en) * | 2015-12-18 | 2019-01-08 | At&T Intellectual Property I, L.P. | Information broadcast |
CN110635998B (zh) * | 2018-06-22 | 2021-10-26 | 华为技术有限公司 | 一种数据传输方法、相关设备及计算机存储介质 |
CN114501563B (zh) * | 2019-09-30 | 2024-05-03 | Oppo广东移动通信有限公司 | 无线通信方法、装置和网络设备 |
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Also Published As
Publication number | Publication date |
---|---|
US20100098024A1 (en) | 2010-04-22 |
JPWO2008065823A1 (ja) | 2010-03-04 |
EP2088793A4 (en) | 2011-09-14 |
CN101548563A (zh) | 2009-09-30 |
EP2088793A1 (en) | 2009-08-12 |
JP4726960B2 (ja) | 2011-07-20 |
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