JP2009206815A - Packet communication system, radio base station, radio terminal and packet communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packet communication system which reduces an overhead and a process load with respect to a real-time communicating packet in a system configuration which transfers a packet between radio base stations upon handover of a radio terminal. <P>SOLUTION: In the packet communication system, when a packet received from a first radio base station 1A is the real-time communicating packet, an IRTP part 12B, an RLP part 13B, and an SP part 14B of a second radio base station 1B overleap an insertion of an IRTP header, an RLP header, and an SP header. Further, when a packet received from a second radio base station 1B is the real-time communicating packet, a second receiving part 20B of a radio terminal 2 overleaps a receiving process based on the IRTP header, the RLP header, and the SP header. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a packet communication system, a wireless base station, a wireless terminal, and a packet communication method that can transfer packets between wireless base stations.

  Conventionally, a wireless terminal performs a so-called handover in which a connection destination is switched to a wireless base station with better conditions during movement or the like. In such a handover, a packet communication system has been proposed in which a packet to be transmitted to a radio terminal is transferred from a handover source radio base station to a handover destination radio base station. An example of a packet communication system that employs such a scheme is UMB (Ultra Mobile Broadband) whose standard is being developed in 3GPP2 (Third Generation Partnership Project 2) (see Non-Patent Document 1).

  In such a packet communication system, a radio terminal receives a packet transferred from a handover source radio base station to a handover destination radio base station from the handover destination radio base station. As a result, a packet that has not been transmitted to the wireless terminal in the handover source wireless base station can be transmitted from the handover destination wireless base station to the wireless terminal, and packet loss of the packet to be transmitted to the wireless terminal is reduced.

  In such a packet communication system, each of a handover source radio base station and a handover destination radio base station inserts control data used for controlling downlink communication with a radio terminal as a packet header.

Then, the radio terminal executes a reception process based on each control data inserted in the packet received from the handover destination radio base station. Specifically, the radio terminal executes a reception process based on the control data inserted by the handover source radio base station after the reception process based on the control data inserted by the handover destination radio base station. Such a method is advantageous in terms of uniformizing and unifying reception processing.
"Overview for Ultra Mobile Broadband (UMB) Air Interface Specification (3GPP2 C.S0084-000-0)", [online], [Search February 20, 2008], <URL: http: //www.3gpp2. org / Public_html / specs / C.S0084-000-0_v2.0_070904.pdf>

  However, when each of the handover source radio base station and the handover destination radio base station inserts control data into the packet, the ratio of the control data (header) in the packet received by the radio terminal from the handover destination radio base station Some overhead increases. In particular, since the packet of a specific type used for real-time communication has a smaller packet size than other types of packets, the increase in overhead is a serious problem.

  Further, the radio terminal performs a reception process based on the control data inserted into the packet by the handover source radio base station and a reception process based on the control data inserted into the packet by the handover destination radio base station. Processing load increases. In particular, a packet of a specific type as described above requires a small processing delay as compared with other types of packets, and thus an increase in processing delay due to an increase in processing load becomes a serious problem.

  Accordingly, the present invention has been made to solve the above-described problems, and can reduce overhead and processing load for a specific type of packet in a system configuration in which packet transfer is performed between radio base stations at the time of handover of a radio terminal. An object of the present invention is to provide a packet communication system, a radio base station, a radio terminal, and a packet communication method.

  In order to solve the above-described problems, the present invention has the following aspects. First, a first aspect of the present invention includes a first radio base station (first radio base station 1A) and a second radio base station (second radio base station 1B) capable of communicating with the first radio base station. A packet communication system (packet communication system 10) including a wireless terminal (wireless terminal 2) that switches a connection destination from the first wireless base station to the second wireless base station, wherein the first wireless base station First control data (RLP header (A), SP header (A), RP header used for downlink communication control between the wireless terminal and the first wireless base station for a packet to be transmitted to the wireless terminal (A)) inserts the first control data insertion unit (RLP unit 13A, SP unit 14A, RP unit 15A) and the packet in which the first control data is inserted at the time of switching the connection destination. 2 Transfer to radio base station A packet transfer unit (RP unit 15A), wherein the second radio base station performs downlink communication between the radio terminal and the second radio base station for the packet received from the first radio base station. Second control data insertion unit (IRTP unit 12B, RLP unit) for inserting second control data (IRTP header (A), RLP header (B), SP header (B), RP header (B)) used for control of 13B, SP unit 14B, RP unit 15B), and a packet transmission unit (PCP / MAC / PHY unit 16B) that transmits the packet in which the first control data and the second control data are inserted to the wireless terminal; The wireless terminal includes a first reception processing unit (first reception processing) that performs reception processing based on the first control data inserted in the packet received from the second wireless base station. 20A) and a second reception processing unit (second reception processing unit 20B) that executes a reception process based on the second control data inserted in the packet received from the second radio base station, The second control data insertion unit omits the insertion of the second control data when the packet received from the first radio base station is a packet of a specific type, and the second reception processing unit When the packet received from the radio base station is the packet of the specific type, the gist is to omit the reception process based on the second control data.

  According to such an aspect, it is possible to provide a packet communication system that can reduce overhead and processing load on a specific type of packet in a system configuration that performs packet transfer between radio base stations at the time of handover of a radio terminal.

  A second aspect of the present invention relates to the first aspect of the present invention, wherein the first radio base station encrypts the packet to be transmitted to the radio terminal (first encryption unit (RLP unit 13A)). The second radio base station further includes a second encryption unit (RLP unit 13B) that encrypts the packet received from the first radio base station, and the radio terminal includes the second radio base station A first decryption unit (RLP unit 23A) that performs decryption corresponding to the encryption performed by the first encryption unit on the packet received from the base station, and the packet received from the second radio base station A second decryption unit (RLP unit 23B) that performs decryption corresponding to the encryption performed by the second encryption unit on the packet, wherein the second encryption unit includes the first wireless unit The packet received from the base station is the specific type of packet. The packet received from the first radio base station is omitted, and the second decryption unit is configured such that the packet received from the second radio base station is the packet of the specific type. In this case, the gist is to omit the decryption corresponding to the encryption executed by the second encryption unit.

  A third aspect of the present invention relates to the first aspect of the present invention, wherein the second radio base station retransmits the packet that the radio terminal has failed to receive to the radio terminal (RLP unit). 13B), and when the packet received from the first radio base station is the packet of the specific type, the packet retransmission unit omits retransmission of the packet that the radio terminal has failed to receive. The gist.

  A fourth aspect of the present invention relates to the first aspect of the present invention, wherein the first radio base station determines whether the packet transferred to the second radio base station is the packet of the specific type. A packet type determination unit (RLP unit 13A) for determining the packet, and the packet transfer unit determines that the specific packet is determined when the packet transferred to the second radio base station is a packet of the specific type The gist is to preferentially transfer the packet of the specific type over the packet of a type different from the type to the second radio base station.

  A fifth aspect of the present invention relates to the fourth aspect of the present invention, and is summarized in that the specific type of packet is a packet for real-time communication that transmits voice data.

  A sixth aspect of the present invention relates to the fifth aspect of the present invention, wherein the packet to be transmitted to the wireless terminal includes a payload area into which the audio data is inserted, and the packet type determination unit includes: The gist is to determine whether the packet is of the specific type according to the data size of the payload area.

  A seventh aspect of the present invention relates to the fourth aspect of the present invention, wherein the first radio base station determines that the packet transferred to the second radio base station is the packet of the specific type. A first specific type information insertion unit (RP unit 15A) for inserting first specific type information indicating that the packet is of the specific type into the packet transferred to the second radio base station, When the first specific type information is inserted in the packet received from the first radio base station, the second control data insertion unit converts the packet received from the first radio base station into the packet of the specific type The gist is to omit the insertion of the second control data.

  An eighth aspect of the present invention relates to the seventh aspect of the present invention, wherein the second radio base station has the first specific type information inserted in the packet received from the first radio base station. A second specific type information insertion unit (RP unit 15B) that inserts second specific type information indicating that the packet is of the specific type into the packet transmitted to the wireless terminal, the second receiving process When the second specific type information is inserted in the packet received from the second radio base station, the unit regards the packet received from the second radio base station as the packet of the specific type The gist is to omit the reception process based on the second control data.

  A ninth aspect of the present invention relates to the first aspect of the present invention, wherein the first control data and the second control data are transmitted between the first reception processing unit and the second reception processing unit. The gist of the data is the data (IRTP header) used for the transfer of.

  A tenth aspect of the present invention relates to the first aspect of the present invention, wherein the first control data and the second control data are used for dividing the packet and reconstructing the divided packet. The gist is that it is data (RLP header).

  An eleventh aspect of the present invention relates to the first aspect of the present invention, wherein the first control data and the second control data are data (RLP header) used for retransmission control of the packet. And

  A twelfth aspect of the present invention relates to the first aspect of the present invention, wherein the first control data and the second control data are data (SP header) used for distribution to a stream according to the use of the packet. ).

  A thirteenth aspect of the present invention relates to the first aspect of the present invention, and is summarized in that the specific type of packet is a packet for real-time communication that transmits at least one of audio data and video data.

  A fourteenth aspect of the present invention provides a first wireless communication device (first wireless base station 1A), a second wireless communication device (second wireless base station 1B) capable of communicating with the first wireless communication device, A packet communication system (packet communication system 10) including a third wireless communication device (wireless terminal 2) that switches a connection destination from the first wireless communication device to the second wireless communication device, wherein the first wireless communication device A first control data insertion unit for inserting first control data used for controlling communication between the third wireless communication device and the first wireless communication device for a packet to be transmitted to the third wireless communication device; A packet transfer unit that transfers the packet in which the first control data is inserted to the second wireless communication device at the time of switching the connection destination, and the second wireless communication device includes the first wireless communication From the device A second control data insertion unit that inserts second control data used for controlling communication between the third wireless communication device and the second wireless communication device, the first control data, A packet transmission unit that transmits the packet in which the second control data is inserted to the third wireless communication device, wherein the third wireless communication device is inserted into the packet received from the second wireless communication device. A first reception processing unit that executes reception processing based on the first control data, and a reception processing that executes reception processing based on the second control data inserted in the packet received from the second wireless communication device. A second reception processing unit, and the second control data insertion unit inserts the second control data when the packet received from the first wireless communication device is a packet of a specific type. Omitted, the second reception processing unit, when the packet received from the second wireless communication device is the particular type of packet is summarized as omitting the reception processing based on the second control data.

  According to a fifteenth aspect of the present invention, at the time of switching the connection destination of a wireless terminal (wireless terminal 2), the wireless terminal And a radio base station (second radio base station 1B) that receives the packet in which the first control data used for controlling downlink communication with the other radio base station is inserted, and that is the switching destination of the connection destination A control data insertion unit (IRTP unit) that inserts second control data used for controlling downlink communication between the radio base station and the radio terminal to the packet received from the other radio base station. 12B, RLP unit 13B, SP unit 14B, RP unit 15B) and a packet transmission unit (PCP) for transmitting the packet in which the first control data and the second control data are inserted to the wireless terminal MAC / PHY unit 16B), and the control data insertion unit omits the insertion of the second control data when the packet received from the other radio base station is a packet of a specific type. And

  According to a sixteenth aspect of the present invention, when the connection destination is switched from the first radio base station (first radio base station 1A) to the second radio base station (second radio base station 1B), the first radio base station A wireless terminal (wireless terminal 2) that receives a packet transferred from a station to the second wireless base station from the second wireless base station, and is inserted into the packet received from the second wireless base station, A first reception processing unit (first reception processing unit 20A) that performs reception processing based on first control data used for controlling downlink communication between a wireless terminal and the first wireless base station; and the second wireless base A second reception processing unit (second reception) that performs reception processing based on second control data that is inserted into the packet received from the station and is used to control downlink communication between the wireless terminal and the second wireless base station Processing unit 20B), Serial second reception processing unit, the packet received from the second wireless base station when a packet of a particular type, and summarized in that omitting a reception processing based on the second control data.

  According to a seventeenth aspect of the present invention, there is provided a first radio base station, a second radio base station capable of communicating with the first radio base station, and a connection destination from the first radio base station to the second radio base station. A packet communication method using a radio terminal to be switched, wherein the first radio base station controls downlink communication between the radio terminal and the first radio base station for a packet to be transmitted to the radio terminal Inserting the first control data used in the transmission, and the first radio base station transfers the packet in which the first control data is inserted to the second radio base station when switching the connection destination And second control data used for controlling downlink communication between the radio terminal and the second radio base station for the packet received from the first radio base station by the second radio base station. Step to insert The second radio base station transmitting the packet in which the first control data and the second control data are inserted to the radio terminal; and the radio terminal receives from the second radio base station. Performing a reception process based on the second control data inserted into the packet, and the wireless terminal to the first control data inserted into the packet received from the second radio base station. Performing the receiving process based on the step, and inserting the second control data, the packet received by the second radio base station from the first radio base station is a packet of a specific type, The insertion of the second control data is omitted, and in the step of executing the reception process based on the second control data, the wireless terminal receives from the second wireless base station If serial packet is the particular type of packet, it is summarized in that the reception processing based on the second control data is omitted.

  According to the present invention, a packet communication system, a radio base station, a radio terminal, and packet communication that can reduce overhead and processing load for a specific type of packet in a system configuration that performs packet transfer between radio base stations at the time of handover of a radio terminal. Can provide a method.

  Next, an embodiment of the present invention will be described with reference to the drawings. Specifically, (1) schematic configuration of packet communication system, (2) detailed configuration of packet communication system, (3) configuration of packet, (4) schematic operation of packet communication system, (5) handover source radio base station (6) Operation of handover destination radio base station, (7) Operation of radio terminal, (8) Action and effect, (9) Other embodiments will be described.

  In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

(1) Schematic configuration of packet communication system First, a schematic configuration of a packet communication system, specifically (1.1) overall schematic configuration, (1.2) schematic configuration of a radio base station, (1.3) radio A schematic configuration of the terminal will be described.

(1.1) Overall Schematic Configuration FIG. 1 is an overall schematic configuration diagram of a packet communication system 10 according to the present embodiment.

  As shown in FIG. 1, the packet communication system 10 includes a first radio base station 1A, a second radio base station 1B, a radio terminal 2, an access gateway 3, and the Internet 4. In this embodiment, the packet communication system 10 has a configuration based on 3GPP2 UMB Air Interface (hereinafter simply referred to as “UMB system”), which is one of wide-area IP broadband systems capable of high-speed communication.

  The first radio base station 1A, the second radio base station 1B, and the access gateway 3 are connected to each other via a router (not shown). The first radio base station 1 </ b> A and the second radio base station 1 </ b> B can communicate with the Internet 4 via the access gateway 3. Further, the first radio base station 1A and the second radio base station 1B can communicate with each other (that is, communication between base stations).

  The first radio base station 1A and the second radio base station 1B perform radio communication with the radio terminal 2 located in the communicable area. The radio terminal 2 compares the reception quality of radio signals (for example, pilot signals) transmitted by the first radio base station 1A and the second radio base station 1B and connects to the higher reception quality.

  In the example of FIG. 1, the wireless terminal 2 moves from the communicable area of the first radio base station 1A toward the communicable area of the second radio base station 1B, and the second radio base station 1A A handover for switching the connection destination to the base station 1B is executed.

  Here, downlink packets to be transmitted to the radio terminal 2 remain in the first radio base station 1A and the communication path between the first radio base station 1A and the access gateway 3. Therefore, the first radio base station 1A serves as a relay station (anchor) between the access gateway 3 and the second radio base station 1B, and performs communication between base stations for packets not transmitted to the radio terminal 2 to the second radio base station 1B. Use and transfer. Thereby, a handover with less packet loss is realized.

  In the UMB system, a radio base station that functions as a relay station between the access gateway 3 and the second radio base station 1B, like the first radio base station 1A, is referred to as a DAP (Data Attachment Point), and the second radio base station 1B A wireless base station that actually transmits downlink packets to the wireless terminal 2 is referred to as FLSE (Forward Link Serving eBS), and a wireless base that actually receives upstream packets from the wireless terminal 2 such as the second wireless base station 1B. The station is called RLSE (Reverse Link Serving eBS). In some cases, FLSE and RLSE are different radio base stations.

  In particular, in the UMB system, the second radio base station 1B gives information indicating the first radio base station 1A that is the handover source to the packet scheduled to be transmitted by the first radio base station 1A, and the second radio base station It is treated as a normal packet transmitted from 1B, and is transmitted to the wireless terminal 2 after performing predetermined processing.

  Specifically, each of the first radio base station 1A as the handover source and the second radio base station 1B as the handover destination inserts control data used for controlling downlink communication with the radio terminal 2 as a packet header. . In the following, the control data (header) inserted into the packet by the first radio base station 1A as the handover source is referred to as “first control data” as appropriate, and the control data inserted into the packet at the second radio base station 1B as the handover destination (Header) is appropriately referred to as “second control data”. The radio terminal 2 executes reception processing based on the first control data and the second control data inserted in the packet received from the second radio base station 1B that is the handover destination.

  In the UMB system, the following (a) to (c) are assumed as a method of switching the DAP from the first radio base station 1A as the handover source to the second radio base station 1B as the handover destination.

(A) Method for switching DAP from first radio base station 1A to second radio base station 1B after a certain period of time has passed since handover (b) When there is no user data traffic for transmission / reception, DAP is switched to first radio base station (C) When transmission of unprocessed / untransmitted data to the second radio base station 1B is completed in the first radio base station 1B, the DAP is switched to the first radio base station 1B. Switching from station 1A to second radio base station 1B

  Thus, by switching the DAP from the first radio base station 1A to the second radio base station 1B, DAP and FLSE become the same radio base station.

  In the following embodiment, a case will be described in which the first radio base station 1A is DAP and the second radio base station 1B is FLSE in downlink communication (forward link). A case where the wireless terminal 2 performs real-time communication such as voice communication (VoIP) or media communication will be described.

(1.2) Schematic Configuration of Radio Base Station FIG. 2 is a schematic configuration diagram showing a schematic configuration of the first radio base station 1A. Since the schematic configuration of the second radio base station 1B is the same as that of the first radio base station 1A, description of the schematic configuration of the second radio base station 1B is omitted.

  As illustrated in FIG. 2, the first radio base station 1A includes an RF unit 101, a control unit 102, an I / F unit 103, and a storage unit 104.

  The RF unit 101 includes an LNA, a power amplifier, an up converter, a down converter, and the like, and transmits and receives radio signals. The I / F unit 103 is wired to the second radio base station 1B and the access gateway 3 via a router or the like.

  The control unit 102 is configured by a CPU, for example, and controls various functions provided in the first radio base station 1A. Further, the control unit 102 executes processing according to various protocols described later.

  The storage unit 104 is configured by a memory, for example, and stores various information used for control and the like in the first radio base station 1A. In addition, the storage unit 104 includes a buffer unit 104 a that temporarily stores data to be transmitted to and received from the wireless terminal 2. The buffer unit 104a has a plurality of transmission queues according to priority.

(1.3) Schematic Configuration of Radio Terminal FIG. 3 is a schematic configuration diagram showing a schematic configuration of the radio terminal 2.

  As illustrated in FIG. 3, the wireless terminal 2 includes an RF unit 201, an operation unit 202, a control unit 203, an audio codec unit 204, a microphone 205, a speaker 206, a display unit 207, and a storage unit 208.

  The RF unit 201 includes an LNA, a power amplifier, an up converter, a down converter, and the like, and transmits and receives radio signals. The control unit 203 is configured by a CPU, for example, and controls various functions provided in the wireless terminal 2. The control unit 203 executes processing according to various protocols described later. The storage unit 208 is configured by a memory, for example, and stores various types of information used for control in the wireless terminal 2 and the like.

  The display unit 207 displays an image received via the control unit 203 and displays operation details (such as an input telephone number and an address). The operation unit 202 is configured by a numeric keypad, function keys, and the like, and is an interface used for inputting user operation details.

  The microphone 205 collects sound and inputs sound data based on the collected sound to the control unit 203 via the sound codec unit 204. The speaker 206 outputs audio based on the audio data acquired from the control unit 203 via the audio codec unit 204.

  The audio codec unit 204 is, for example, an audio codec method G.264. 729. G. 729 is a method of sampling (sampling) an analog telephone band (3.4 kHz≈4 kHz) signal at 8 kHz and realizing a transmission rate of 8 kbps, and has an adaptability in communication using a narrow band transmission path. .

(2) Detailed Configuration of Packet Communication System Next, a detailed configuration of the packet communication system 10, specifically, (2.1) Outline of UMB system, (2.2) Detailed configuration of handover source radio base station, (2 .3) A detailed configuration of the handover destination radio base station, (2.4) a detailed configuration of the radio terminal will be described.

(2.1) UMB System Overview FIG. 4 is a diagram for explaining the first reception processing unit 20A and the second reception processing unit 20B of the wireless terminal 2.

  In the UMB system, a plurality of receiving modules exist in the wireless terminal 2 in accordance with the number of wireless base stations with which communication is performed. In the present embodiment, the first reception processing unit 20A is a reception module corresponding to the first radio base station 1A. The second reception processing unit 20B is a reception module corresponding to the second radio base station 1B.

  First, the second reception processing unit 20B receives the packet via the radio section, and after receiving the packet according to the control data inserted by the second radio base station 1B, internally transfers the packet to the first reception processing unit 20A. . The first reception processing unit 20A performs the same reception process as when receiving a packet directly from the first radio base station 1A.

  In this way, at the time of handover, the radio terminal 2 passes through the second reception processing unit 20B corresponding to the second radio base station 1B that is the handover destination, and the first radio base station 1A that corresponds to the first radio base station 1A that is the handover source. Protocol processing of the reception processing unit 20A is performed. Such a method has an advantage in terms of uniformization and unification of reception processing (reception module).

  In the present embodiment, for the real-time communication packet such as a voice packet, a part of the processing of the second reception processing unit 20B is omitted, and the process proceeds to the processing of the first reception processing unit 20A. Specifically, protocols such as IETF RFC1889 Real Time Transport Protocol (RTP) are applied in voice communication (VoIP) and media communication.

  In the UMB system, IP tunneling technology represented by IETF RFC3931 Layer Two Tunneling Protocol-Version 3 (L2TPv3) and IETF RFC2784 Generic Routing Encapsulation (GRE) is adopted. Specifically, GRE is adopted for the user data bearer between the first radio base station 1A and the access gateway 3, and L2TPv3 is adopted for the user data bearer between the first radio base station 1A and the second radio base station 1B. Is done.

  FIG. 5 is a functional block configuration diagram showing detailed configurations of the first radio base station 1A, the second radio base station 1B, and the radio terminal 2. FIG. 5 also serves as a protocol stack diagram according to the UMB system.

  As shown in FIG. 5, the first radio base station 1A includes an APP unit 11A, an IRTP unit 12A, an RLP unit 13A, an SP unit 14A, an RP unit 15A, and a PCP / MAC / PHY unit 16A. The second radio base station 1B includes an APP unit 11B, an IRTP unit 12B, an RLP unit 13B, an SP unit 14B, an RP unit 15B, and a PCP / MAC / PHY unit 16B.

  The first reception processing unit 20A of the wireless terminal 2 includes an APP unit 21A, an IRTP unit 22A, an RLP unit 23A, an SP unit 24A, an RP unit 25A, and a PCP / MAC / PHY unit 26A. The second reception processing unit 20B of the wireless terminal 2 includes an APP unit 21B, an IRTP unit 22B, an RLP unit 23B, an SP unit 24B, an RP unit 25B, and a PCP / MAC / PHY unit 26B.

  The APP unit 11A, the APP unit 11B, the APP unit 21A, and the APP unit 21B execute processing based on APP (Application Protocol) in the UMB system. APP is a protocol having a plurality of standard protocols such as IP (Internet Protocol), ROHC (RObust Header Compression), and EAP (Extensible Authentication Protocol).

  The IRTP unit 12A, the IRTP unit 12B, the IRTP unit 22A, and the IRTP unit 22B execute processing based on IRTP (Inter-Route Tunneling Protocol) in the UMB system. IRTP is a protocol having a transfer function between modules in a wireless terminal.

  The RLP unit 13A, the RLP unit 13B, the RLP unit 23A, and the RLP unit 23B execute processing based on RLP (Radio Link Protocol) in the UMB system. RLP is a protocol having packet division, reconstruction, and downlink retransmission control functions. Specifically, RLP defines a SAR (Segmentation And Reassembly) sub-protocol that performs packet division and reassembly, and a QN (Quick Nak) sub-protocol that performs retransmission control. In the present embodiment, it is assumed that the RLP unit 13A, the RLP unit 13B, the RLP unit 23A, and the RLP unit 23B also have a function of executing packet encryption / decryption.

  The SP unit 14A, the SP unit 14B, the SP unit 24A, and the SP unit 24B execute processing based on SP (Stream Protocol) in the UMB system. SP is a protocol that distributes the divided upper packets to respective streams (packet streams). Here, in the UMB system, for example, the following uses are defined as a stream. Stream 0: Broadcast Signaling on forward link and Reserved on reverse link, Stream 1: Best Effort Delivery Signaling, Stream 2: Reliable Delivery Signaling, Stream 3: Broadcast Inter Route Tunneling on forward link and Reserved on reverse link, Stream 4: Best Effort Delivery Inter Route Tunneling etc.

  The RP unit 15A, RP unit 15B, RP unit 25A, and RP unit 25B execute processing based on RP (Route Protocol) in the UMB system. RP is a protocol for selecting a communication path (service route) between a wireless terminal and a wireless base station.

  The RLP, SP, and RP protocols described above are protocols in the radio link layer defined by the UMB system.

  PCP / MAC / PHY unit 16A, PCP / MAC / PHY unit 16B. The PCP / MAC / PHY unit 26A and the PCP / MAC / PHY unit 26B execute processing based on PCP / MAC / PHY (Packet Consolidation Protocol / MAC / PHY) in the UMB system. PCP / MAC / PHY is a protocol having a function of encapsulating upper packets and wirelessly transmitting them.

(2.2) Detailed Configuration of Handover Source Radio Base Station The detailed configuration of the handover source first radio base station 1A will be described with reference to FIG.

  As the data flow immediately after the handover, the first radio base station 1A divides the APP data from the APP unit 11A in the RLP unit 13A, and passes it through the SP unit 14A and the RP unit 15A to the second radio base station 1B. Forward. At that time, the RLP unit 13A adds an RLP header (A), the SP unit 14A adds an SP header (A), and the RP unit 15A adds an RP header (A).

  In the present embodiment, the RLP unit 13A, the SP unit 14A, and the RP unit 15A have first control data (RLP header (A), SP) used for controlling downlink communication between the radio terminal 2 and the first radio base station 1A. A first control data insertion unit for inserting the header (A) and the RP header (A) is configured. Further, the RP unit 15A configures a packet transfer unit that transfers a packet in which the first control data is inserted to the second radio base station 1B at the time of handover of the radio terminal 2.

  The RLP unit 13A functions as a first encryption unit that encrypts a packet, and also has a function of retransmitting a packet that the wireless terminal 2 has failed to receive to the wireless terminal 2.

(2.3) Detailed Configuration of Handover Destination Radio Base Station Next, with reference to FIG. 5, a detailed configuration of the second radio base station 1B that is the handover destination will be described.

  The second radio base station 1B sends the packet received from the first radio base station 1A to the radio terminal 2 via the IRTP unit 12B, the RLP unit 13B, the SP unit 14B, the RP unit 15B, and the PCP / MAC / PHY unit 16B. Send. In the IRTP unit 12B, an IRTP header (A) indicating that the first radio base station 1A is the transmission source is inserted. The RLP unit 13B adds an RLP header (B), the SP unit 14B adds an SP header (B), and the RP unit 15B adds an RP header (B).

  In this embodiment, the IRTP unit 12B, the RLP unit 13B, the SP unit 14B, and the RP unit 15B perform downlink communication between the radio terminal 2 and the second radio base station 1B for the packet received from the first radio base station 1A. 2nd control data insertion part which inserts the 2nd control data (IRTP header (A), RLP header (B), SP header (B), RP header (B)) used for control of this is constituted. The PCP / MAC / PHY unit 16B constitutes a packet transmission unit that transmits to the wireless terminal 2 a packet in which the first control data and the second control data are inserted.

  In addition, the RLP unit 13B functions as a second encryption unit that encrypts a packet, and also functions as a packet retransmission unit that retransmits a packet that the wireless terminal 2 has failed to receive to the wireless terminal 2.

(2.4) Detailed Configuration of Wireless Terminal The detailed configuration of the wireless terminal 2 will be described with reference to FIG.

  The second reception processing unit 20B executes a reception process based on the second control data inserted in the packet received from the second radio base station 1B. Specifically, the RP unit 25B, the SP unit 24B, and the RLP unit 23B, with respect to a packet received by the PCP / MAC / PHY unit 26B of the second reception processing unit 20B, B) Remove the SP header (B) and RLP header (B) to form an IRTP packet. The IRTP unit 22B transfers the packet to the RP unit 25A of the first reception processing unit 20A according to the IRTP header constituting the second control data. Then, the first reception processing unit 20A executes reception processing based on the first control data (RLP header (A), SP header (A), RP header (A)) inserted in the packet.

  The RLP unit 23A functions as a first decryption unit that performs decryption corresponding to the encryption performed by the RLP unit 13A. The RLP unit 23B functions as a second decryption unit that performs decryption corresponding to the encryption performed by the RLP unit 13B.

  FIG. 6 is a diagram showing a data flow when processing a packet for real-time communication. As shown in FIG. 6, the RP unit 25B transfers the packet for the real-time communication packet to the RP unit 25A of the first reception processing unit 20A, not the SP unit 24B, which is an upper protocol of the RP unit 25B.

(3) Packet Configuration FIG. 7 is a diagram showing a packet configuration used in the packet communication system 10.

  The RLP unit 13A and the RLP unit 13B divide (fragment) APP data as shown in FIG. 7A, add an RLP header to the divided data, and generate an RLP packet shown in FIG. 7B. In the RLP header, data indicating the start point and end point of fragmented data, a sequence number used for retransmission processing, and the like are inserted.

  The SP unit 14A and the SP unit 14B add an SP header to the RLP packet shown in FIG. 7B to generate the SP packet shown in FIG. In the SP header, data used for distribution to a stream according to the use of the RLP packet is inserted.

  The RP unit 15A and the RP unit 15B add an RP header to the SP packet illustrated in FIG. 7C to generate the RP packet illustrated in FIG. Data for identifying the service route is inserted into the RP header.

  Furthermore, the IRTP unit 12B adds an IRTP header indicating the handover source first radio base station 1A. As a result, the total of RLP header, SP header, RP header, and IRTP header is 3 bytes to 33 bytes.

(4) Schematic operation of packet communication system Next, a schematic operation of the packet communication system, specifically, (4.1) Operation pattern 1 of the packet communication system, and (4.2) Operation pattern 2 of the packet communication system. explain. Here, the operation pattern 1 is an operation pattern applied to a packet other than the real-time communication packet. The operation pattern 2 is an operation pattern applied to the real-time communication packet.

(4.1) Operation pattern 1 of packet communication system
FIG. 8 is a conceptual diagram for explaining an operation pattern 1 of the packet communication system.

  As shown in FIG. 8A, the first radio base station 1A encrypts the IP payload received from the access gateway 3, and adds various headers (RLP header (ALP header) for the first radio base station 1A to the data. ), SP header (A), RP header (A)) are added and transferred to the second radio base station 1B.

  The second radio base station 1B that has received this packet sends the encrypted IP payload and various headers (RLP header (A), SP header (A), RP header (A)) for the first radio base station 1A. Further encryption is performed by regarding it as one payload. Then, the second radio base station 1B gives various headers for the second radio base station 1B (RLP header (B), SP header (B), RP header (B), IRTP header (A)), and wireless Transmit to terminal 2.

  As shown in FIG. 8 (b), the wireless terminal 2 performs decoding with reference to the header (RLP header (B), SP header (B), RP header (B)) for the second wireless base station 1B. Apply. The wireless terminal 2 encrypts various headers (RLP header (A), SP header (A), RP header (A), IRTP header (A)) for the first wireless base station 1A and the first wireless base station 1A. To obtain a converted IP payload. Next, the wireless terminal 2 performs decoding with reference to various headers (RLP header (A), SP header (A), RP header (A)) for the first wireless base station 1A, and obtains an IP payload. .

  As described above, for the packets other than the real-time communication packet, each of the first radio base station 1A and the second radio base station 1B performs encryption, and the radio terminal 2 performs decryption twice.

(4.2) Operation pattern 2 of packet communication system
FIG. 9 is a conceptual diagram for explaining an operation pattern 2 of the packet communication system.

  As shown in FIG. 9, the first radio base station 1A encrypts the IP payload received from the access gateway 3, and adds various headers (RLP header (A), SP for the first radio base station 1A to the data. A header (A) and an RP header (A)) are added and transferred to the second radio base station 1B. At this time, the RLP unit 13A of the first radio base station 1A determines that the packet is for real-time communication, and the RP unit 15A inserts first identification information indicating the packet for real-time communication into the packet for real-time communication.

  The second radio base station 1B that has received this packet determines that the packet is for real-time communication based on the first identification information, omits encryption, and uses various headers (RLP headers) for the second radio base station 1B. (B), addition of SP header (B), IRTP header (A)) is also omitted, and transmitted to wireless terminal 2. At that time, the RP unit 15B of the second radio base station 1B inserts the second identification information indicating the real-time communication packet into the real-time communication packet.

  The wireless terminal 2 that has received this packet determines that the packet is for real-time communication based on the second identification information, omits the first decoding, and uses various headers (RLP headers) for the second wireless base station 1B. (B), reception processing based on SP header (B), IRTP header (A)) is omitted. Then, the wireless terminal 2 performs decoding with reference to various headers for the first wireless base station 1A (RLP header (A), SP header (A), RP header (A)) to obtain an IP payload. .

(5) Operation of Handover Source Radio Base Station Next, the operation of the handover source radio base station (that is, the first radio base station 1A), specifically, (5.1) Real-time communication packet discrimination operation; 5.2) An operation flow of the handover source radio base station will be described.

(5.1) Real-Time Communication Packet Discrimination Operation FIG. 10 is a diagram for explaining the real-time communication packet discrimination operation. As described above, the RLP unit 13A of the first radio base station 1A determines whether the packet is for real-time communication. Here, the operation of discriminating voice packets (VoIP packets) as real-time communication packets will be described.

  For example, the voice packet discrimination method is UDP (User Datagram Protocol) and is a technique for discriminating whether or not the voice packet is a continuous packet having an appropriate IP payload size. Although various settings can be considered as criteria for determining an IP payload size appropriate for a voice packet depending on the intended use and QoS policy, the following method is adopted in the present embodiment.

  As a voice encoding method for VoIP applications, G. 729 or the like is employed, it has a characteristic that packets with a small data size are continuously transmitted at short intervals. As shown in FIG. 10, the audio payload size per packet changes depending on the packet transmission interval. For this reason, when the jitter buffer allowed as a system allows up to a 40 ms interval, the upper limit of this data size is 80 bytes including the header portion and the audio data (payload).

  Further, as the characteristics of real-time communication, packets having the same destination IP address, transmission source IP address, UDP destination port number, and UDP transmission source port number are transmitted continuously. For this reason, in addition to the above size determination, communication connections having the same size and the same IP address / UDP port number for a certain number of times (n times) can be regarded as real-time communication.

  When the RLP unit 13A determines that the packet is for real-time communication, the RP unit 15A inserts first identification information indicating the real-time communication packet into the real-time communication packet. Specifically, as shown in FIG. 11, the RP unit 15A sets first identification information indicating that the packet is a VoIP packet in the RP header, and transfers the first identification information to the second radio base station 1B that is FLSE. In FIG. 11, a 7-bit route ID field is added, and the first identification information is inserted into the field.

(5.2) Operation Flow of Handover Source Radio Base Station FIG. 12 is a flowchart showing the operation of the handover source radio base station (that is, the first radio base station 1A).

  In step S <b> 101, the first radio base station 1 </ b> A receives a packet to be transmitted from the access gateway 3 to the radio terminal 2.

  In step S102, the first radio base station 1A determines whether or not it is operating as a DAP. If it is operating as a DAP, the process proceeds to step S103, and if it is not operating as a DAP, the process proceeds to step S108.

  In step S103, the first radio base station 1A determines whether or not it is operating as FLSE. If it is operating as FLSE, the process proceeds to step S108, and if it is not operating as FLSE, the process proceeds to step S104. Here, when the RLP unit 13A of the first radio base station 1A determines that the own station is not FLSE, the RLP unit 13A enables the packet detection function for real-time communication.

  In step S104, the RLP unit 13A of the first radio base station 1A determines whether or not the packet received in step S101 is a voice packet (here, a VoIP packet). If the received packet is a VoIP packet, the process proceeds to step S105. If the received packet is not a VoIP packet, the process proceeds to step S108.

  In step S105, the RLP unit 13A of the first radio base station 1A stores a packet to be transferred to the second radio base station 1B in a high priority queue in the buffer unit 104a. That is, when the packet transferred to the second radio base station 1B is a VoIP packet, the RP unit 15A gives priority to transfer the VoIP packet to the second radio base station 1B over a packet of a different type from the VoIP packet. To work.

  In step S106, the RP unit 15A of the first radio base station 1A inserts first identification information for identifying a VoIP packet into the VoIP packet. In step S107, the RP unit 15A transfers the VoIP packet stored in the buffer unit 104a to the second radio base station 1B.

  On the other hand, in step S108, the RP unit 15A of the first radio base station 1A stores the packet received in step S101 in the normal priority queue in the buffer unit 104a. In step S109, the RP unit 15A determines whether a packet is stored in the high priority queue in the buffer unit 104a. When a packet is stored in the high priority queue, the packet is transferred with priority.

  In step S110, the RP unit 15A of the first radio base station 1A adds a normal RP header to the packet transferred to the second radio base station 1B. In step S111, the RP unit 15A transfers the packet stored in the buffer unit 104a to the second radio base station 1B.

  Thus, when packets other than real-time communication and real-time communication are mixed in the user traffic, the first radio base station 1A temporarily queues packets other than real-time communication in a low-priority buffer. The real-time communication packet is transferred to the second radio base station 1B with the highest priority.

(6) Operation of Handover Destination Radio Base Station FIG. 13 is a flowchart showing the operation of the handover destination radio base station (that is, the second radio base station 1B).

  In step S201, the second radio base station 1B receives a packet to be transmitted to the radio terminal 2 from the first radio base station 1A.

  In step S202, whether or not the packet received from the first radio base station 1A is a VoIP packet is determined based on the first identification information inserted into the RP header by the first radio base station 1A. If the packet received from the first radio base station 1A is a VoIP packet, the process proceeds to step S203. If the packet is other than a VoIP packet, the process proceeds to step S206.

  In step S203, the IRTP unit 12B, the RLP unit 13B, and the SP unit 14B of the second radio base station 1B omit the insertion of the IRTP header (A), the RLP header (B), and the SP header (B).

  In step S204, the RLP unit 13B of the second radio base station 1B also omits the encryption process and the retransmission process.

  In step S205, the RP unit 15B of the second radio base station 1B adds the RP header and inserts the above-described second identification information into the RP header.

  On the other hand, in step S206 after determining that the packet is not a VoIP packet, the IRTP unit 12B, the RLP unit 13B, and the SP unit 14B of the second radio base station 1B set the IRTP header (A), the RLP header (B), and the SP header (B ) Is inserted.

  In step S207, the RLP unit 13B of the second radio base station 1B performs encryption processing and retransmission processing. In step S208, the RP unit 15B of the second radio base station 1B adds a normal RP header.

  In step S209, the PCP / MAC / PHY unit 16B of the second radio base station 1B transmits a packet to the radio terminal 2.

(7) Operation of Wireless Terminal FIG. 14 is a flowchart showing the operation of the wireless terminal 2.

  In step S301, the wireless terminal 2 receives a packet (RP packet) from the second wireless base station 1B.

  In step S302, the radio terminal 2 determines whether the packet received from the second radio base station 1B is a VoIP packet based on the second identification information inserted into the RP header by the second radio base station 1B. . If the packet received from the second radio base station 1B is a VoIP packet, the process proceeds to step S303. When the packet received from the second radio base station 1B is not a VoIP packet, normal reception processing in the UMB system is executed.

  In step S303, the RP unit 25B of the radio terminal 2 removes the RP header of the packet received from the second radio base station 1B. Then, the RP unit 25B internally transfers the packet received from the second radio base station 1B to the RP unit 25A (step S304).

  As a result, the processing of the IRTP unit 22B, RLP unit 23B, and SP unit 24B of the wireless terminal 2 is omitted. Since the processing of the RLP unit 23B is omitted, the decoding and retransmission processing executed by the RLP unit 23B is also omitted.

  In step S305, the APP unit 21A, IRTP unit 22A, RLP unit 23A, SP unit 24A, and RP unit 25A of the wireless terminal 2 execute normal reception processing.

(8) Operation and Effect As described above, when the IRTP unit 12B, RLP unit 13B, and SP unit 14B of the second radio base station 1B are packets received from the first radio base station 1A, they are real-time communication packets. , IRTP header (A), RLP header (B), and SP header (B) are omitted. In addition, the second reception processing unit 20B of the wireless terminal 2 receives the IRTP header (A), the RLP header (B), and the SP header (B) when the packet received from the second wireless base station 1B is a real-time communication packet. The reception process based on is omitted.

  Therefore, according to the packet communication system 10, it is possible to reduce the overhead and processing load on the real-time communication packet while complying with the UMB system. In particular, the wireless terminal 2 is generally driven by a finite battery, and by reducing the processing load on the wireless terminal 2, the operable time of the wireless terminal 2 can be extended.

  In the present embodiment, the RLP unit 13B of the second radio base station 1B encrypts the packet received from the first radio base station 1A when the packet received from the first radio base station 1A is a real-time communication packet. Omitted. When the packet received from the second radio base station 1B is a real-time communication packet, the RLP unit 23B of the radio terminal 2 omits the decryption corresponding to the encryption executed by the RLP unit 13B of the second radio base station 1B. To do. Therefore, by omitting redundant encryption / decryption for the real-time communication packet, the overhead and processing load for the real-time communication packet can be further reduced while conforming to the UMB system.

  In the present embodiment, when the packet received from the first radio base station 1A is a real-time communication packet, the RLP unit 13B of the second radio base station 1B omits retransmission of the packet that the radio terminal 2 has failed to receive. . Here, since the retransmission process is executed between the RLP unit 13A of the first radio base station 1A and the RLP unit 23A of the radio terminal 2, the retransmission process by the RLP unit 13B becomes redundant. By omitting such redundant retransmission processing for real-time communication packets, the overhead and processing load on the real-time communication packets can be further reduced while conforming to the UMB system.

  In the present embodiment, when the RP unit 15A of the first radio base station 1A determines that the packet transferred to the second radio base station 1B is a real-time communication packet, a packet of a different type from the real-time communication packet The packet of the specific type for real-time communication is prioritized and transferred to the second radio base station 1B. In this way, by storing packets other than real-time communication packets in a separate queue and postponing them, the real-time communication packets are preferentially transported, and the transmission delay of the real-time communication packets is reduced, It becomes possible to reduce traffic.

  In the present embodiment, the RLP unit 13A of the first radio base station 1A determines whether or not it is a real-time communication packet according to the data size of the payload area in the packet to be transmitted to the radio terminal 2. As a result, the real-time communication packet can be reliably detected.

  In the present embodiment, the RP unit 15A of the first radio base station 1A indicates that it is a real-time communication packet when it is determined that the packet transferred to the second radio base station 1B is a real-time communication packet. The identification information is inserted into a packet transferred to the second radio base station 1B. The IRTP unit 12B, RLP unit 13B, and SP unit 14B of the second radio base station 1B received from the first radio base station 1A when the identification information is inserted in the packet received from the first radio base station 1A. Considering that the packet is a real-time communication packet, insertion of the IRTP header (A), RLP header (B), and SP header (B) is omitted. Therefore, the second radio base station 1B can easily determine whether or not it is a real-time communication packet, and the time required for the determination is reduced, so that the transmission delay of the real-time communication packet is reduced.

  In the present embodiment, the RP unit 15B of the second radio base station 1B, when the identification information is inserted in the packet received from the first radio base station 1A, displays identification information indicating that it is a real-time communication packet. It is inserted into a packet transmitted to the wireless terminal 2. When the identification information is inserted in the packet received from the second radio base station 1B, the second reception processing unit 20B of the radio terminal 2 receives the packet received from the second radio base station 1B as a real-time communication packet. Therefore, the reception process based on the IRTP header (A), RLP header (B), and SP header (B) is omitted. Therefore, the wireless terminal 2 can easily determine whether or not it is a packet for real-time communication, and the time required for the determination is shortened, so that the transmission delay (processing delay) of the packet for real-time communication is reduced. .

  As described above, according to the present embodiment, the overhead determined by the header is reduced and a redundant process such as encryption / retransmission is omitted for a packet determined to be a real-time communication packet (real-time packet) while conforming to the UMB system. In addition, the transmission quality can be stabilized by transmitting with the highest priority over other packets. In addition, packet loss and delay can be reduced in real-time communication. In particular, it is possible to more reliably avoid sound interruptions, one-way calls, and the like in voice communication.

(9) Other Embodiments As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above-described embodiment, the retransmission processing in the RLP unit 13B and the RLP unit 23B is omitted for the real-time communication packet. However, in addition to the retransmission process in the radio link layer, the retransmission process executed in a layer lower than the radio link layer may be omitted. Specifically, automatic retransmission control (ARQ) executed by the PCP / MAC / PHY unit 16B and the PCP / MAC / PHY unit 26B can be omitted for real-time communication packets.

  In the above-described embodiment, the audio packet is mainly described as an example of the real-time communication packet. However, since the video packet for transmitting the video data may be required to be real-time, the video packet is also a real-time communication packet. include. Alternatively, the present invention is not limited to such a packet for real-time communication, but can be applied to any packet that requires special QoS.

  In the above-described embodiment, the configuration based on the UMB system has been described. However, the present invention is not limited to the UMB system and can be applied to any system that transfers packets between radio base stations at the time of handover.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

1 is an overall schematic configuration diagram of a packet communication system according to an embodiment of the present invention. It is a schematic block diagram which shows schematic structure of the 1st radio base station which concerns on embodiment of this invention. It is a schematic block diagram which shows schematic structure of the radio | wireless terminal which concerns on embodiment of this invention. It is a figure for demonstrating the 1st reception process part of the radio | wireless terminal which concerns on embodiment of this invention, and a 2nd reception process part. It is a functional block block diagram which shows the detailed structure of the 1st radio base station which concerns on embodiment of this invention, a 2nd radio base station, and a radio | wireless terminal. It is a figure which shows the flow of data in the case of processing the packet for real-time communication which concerns on embodiment of this invention. It is a figure which shows the structure of the packet used in the packet communication system which concerns on embodiment of this invention. It is a conceptual diagram for demonstrating the operation pattern 1 of the packet communication system which concerns on embodiment of this invention. It is a conceptual diagram for demonstrating the operation pattern 2 of the packet communication system which concerns on embodiment of this invention. It is a figure for demonstrating the discrimination | determination operation | movement of the packet for real-time communication which concerns on embodiment of this invention. It is a figure which shows the 1st identification information to the effect of being a VoIP packet in the RP header which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the 1st radio base station which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the 2nd wireless base station which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the radio | wireless terminal which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1A ... 1st wireless base station, 1B ... 2nd wireless base station, 2 ... Wireless terminal, 3 ... Access gateway, 4 ... Internet, 10 ... Packet communication system, 11A, 11B, 21A, 21B ... APP part, 12A, 12B , 22A, 22B ... IRTP unit, 13A, 13B, 23A, 23B ... RLP unit, 14A, 14B, 24A, 24B ... SP unit, 15A, 15B, 25A, 25B ... RP unit, 16A, 16B, 26A, 26B ... PCP / MAC / PHY unit, 20A ... first reception processing unit, 20B ... second reception processing unit, 101 ... RF unit, 102 ... control unit, 103 ... I / F unit, 104 ... storage unit, 104a ... buffer unit, 201 ... RF unit, 202 ... operation unit, 203 ... control unit, 204 ... voice codec unit, 205 ... microphone, 206 ... speaker, 207 ... display unit, 208 ...憶部

Claims (17)

A packet communication system including a first radio base station, a second radio base station that can communicate with the first radio base station, and a radio terminal that switches a connection destination from the first radio base station to the second radio base station Because
The first radio base station is
A first control data insertion unit that inserts first control data used for controlling downlink communication between the wireless terminal and the first wireless base station for a packet to be transmitted to the wireless terminal;
A packet transfer unit for transferring the packet in which the first control data is inserted to the second radio base station at the time of switching the connection destination;
The second radio base station is
A second control data insertion unit that inserts second control data used for controlling downlink communication between the radio terminal and the second radio base station for the packet received from the first radio base station;
A packet transmission unit that transmits the packet in which the first control data and the second control data are inserted to the wireless terminal;
The wireless terminal is
A first reception processing unit that performs a reception process based on the first control data inserted in the packet received from the second radio base station;
A second reception processing unit that executes a reception process based on the second control data inserted in the packet received from the second radio base station;
The second control data insertion unit omits the insertion of the second control data when the packet received from the first radio base station is a packet of a specific type;
The packet communication system, wherein the second reception processing unit omits reception processing based on the second control data when the packet received from the second radio base station is the packet of the specific type. The first radio base station further includes a first encryption unit that encrypts the packet to be transmitted to the radio terminal,
The second radio base station further includes a second encryption unit that encrypts the packet received from the first radio base station,
The wireless terminal is
A first decryption unit that performs decryption corresponding to encryption performed by the first encryption unit on the packet received from the second radio base station;
A second decryption unit that performs decryption corresponding to the encryption performed by the second encryption unit on the packet received from the second radio base station;
The second encryption unit omits encryption of the packet received from the first radio base station when the packet received from the first radio base station is the packet of the specific type;
The second decryption unit omits decryption corresponding to encryption performed by the second encryption unit when the packet received from the second radio base station is the packet of the specific type. The packet communication system according to 1. The second radio base station further includes a packet retransmission unit that retransmits the packet that the radio terminal has failed to receive to the radio terminal,
2. The packet communication according to claim 1, wherein the packet retransmission unit omits retransmission of the packet that the wireless terminal has failed to receive when the packet received from the first wireless base station is the packet of the specific type. system. The first radio base station further includes a packet type determination unit that determines whether the packet transferred to the second radio base station is the packet of the specific type,
The packet transfer unit prioritizes the packet of the specific type over a packet of a type different from the specific type when it is determined that the packet transferred to the second radio base station is the packet of the specific type. 2. The packet communication system according to claim 1, wherein the packet communication system transfers the packet to the second radio base station.   The packet communication system according to claim 4, wherein the specific type of packet is a packet for real-time communication that transmits voice data. The packet to be transmitted to the wireless terminal includes a payload area into which the audio data is inserted,
The packet communication system according to claim 5, wherein the packet type determination unit determines whether the packet is the specific type according to the data size of the payload area. When it is determined that the packet transferred to the second radio base station is the packet of the specific type, the first radio base station includes first specific type information indicating that the packet is of the specific type A first specific type information insertion unit that inserts into the packet transferred to the second radio base station;
When the first specific type information is inserted in the packet received from the first radio base station, the second control data insertion unit determines that the packet received from the first radio base station is the specific type. The packet communication system according to claim 4, wherein the packet communication system is considered to be a packet and insertion of the second control data is omitted. When the first specific type information is inserted in the packet received from the first radio base station, the second radio base station receives second specific type information indicating that the packet is of the specific type. A second specific type information insertion unit that inserts into the packet transmitted to the wireless terminal;
When the second specific type information is inserted in the packet received from the second radio base station, the second reception processing unit converts the packet received from the second radio base station into the packet of the specific type The packet communication system according to claim 7, wherein the reception process based on the second control data is omitted.   2. The packet communication system according to claim 1, wherein the first control data and the second control data are data used for transferring the packet between the first reception processing unit and the second reception processing unit.   2. The packet communication system according to claim 1, wherein the first control data and the second control data are data used for dividing the packet and reconstructing the divided packet.   2. The packet communication system according to claim 1, wherein the first control data and the second control data are data used for retransmission control of the packet.   2. The packet communication system according to claim 1, wherein the first control data and the second control data are data used for distribution to a stream according to a use of the packet.   2. The packet communication system according to claim 1, wherein the specific type of packet is a packet for real-time communication that transmits at least one of audio data and video data. A first wireless communication device; a second wireless communication device capable of communicating with the first wireless communication device; and a third wireless communication device that switches a connection destination from the first wireless communication device to the second wireless communication device. A packet communication system,
The first wireless communication device is:
A first control data insertion unit that inserts first control data used for controlling communication between the third wireless communication device and the first wireless communication device for a packet to be transmitted to the third wireless communication device;
A packet transfer unit that transfers the packet in which the first control data is inserted to the second wireless communication device at the time of switching the connection destination;
The second wireless communication device is
A second control data insertion unit that inserts second control data used for controlling communication between the third wireless communication device and the second wireless communication device with respect to the packet received from the first wireless communication device;
A packet transmission unit that transmits the packet in which the first control data and the second control data are inserted to the third wireless communication device;
The third wireless communication device is
A first reception processing unit that executes a reception process based on the first control data inserted in the packet received from the second wireless communication device;
A second reception processing unit that executes a reception process based on the second control data inserted in the packet received from the second wireless communication device;
The second control data insertion unit omits the insertion of the second control data when the packet received from the first wireless communication device is a packet of a specific type;
The packet communication system, wherein the second reception processing unit omits reception processing based on the second control data when the packet received from the second wireless communication device is the packet of the specific type. When switching the connection destination of the wireless terminal, the first control data used for controlling the downlink communication between the wireless terminal and the other wireless base station is transmitted from another wireless base station that is the connection source switching source. A radio base station that receives the inserted packet and is a switching destination of the connection destination,
A control data insertion unit that inserts second control data used for controlling downlink communication between the radio base station and the radio terminal for the packet received from the other radio base station;
A packet transmission unit that transmits the packet in which the first control data and the second control data are inserted to the wireless terminal;
The control data insertion unit is a radio base station that omits insertion of the second control data when the packet received from the other radio base station is a packet of a specific type. A radio terminal that receives, from the second radio base station, a packet transferred from the first radio base station to the second radio base station when switching a connection destination from the first radio base station to the second radio base station Because
A first reception process that is inserted into the packet received from the second radio base station and executes a reception process based on first control data used for controlling downlink communication between the radio terminal and the first radio base station And
A second reception process that is inserted into the packet received from the second radio base station and performs a reception process based on second control data used for controlling downlink communication between the radio terminal and the second radio base station; With
The second reception processing unit is a wireless terminal that omits reception processing based on the second control data when the packet received from the second radio base station is a packet of a specific type. Packet communication using a first radio base station, a second radio base station that can communicate with the first radio base station, and a radio terminal that switches a connection destination from the first radio base station to the second radio base station A method,
The first radio base station inserting first control data used for controlling downlink communication between the radio terminal and the first radio base station into a packet to be transmitted to the radio terminal;
The first radio base station transferring the packet with the first control data inserted to the second radio base station at the time of switching the connection destination;
The second radio base station inserts second control data used for controlling downlink communication between the radio terminal and the second radio base station into the packet received from the first radio base station. When,
The second radio base station transmitting the packet into which the first control data and the second control data are inserted to the radio terminal;
The wireless terminal performing a receiving process based on the second control data inserted in the packet received from the second wireless base station;
The wireless terminal includes a step of performing reception processing based on the first control data inserted in the packet received from the second wireless base station,
In the step of inserting the second control data, when the packet received by the second radio base station from the first radio base station is a packet of a specific type, the insertion of the second control data is omitted,
In the step of executing the reception process based on the second control data, when the packet received by the wireless terminal from the second wireless base station is the packet of the specific type, the reception process based on the second control data is performed Packet communication method to be omitted.

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