CN102761921B - Wireless communication system - Google Patents

Abstract

The invention discloses a wireless communication system which comprises a mobile source base station, a mobile destination base station and a mobile station. The mobile station comprises a unit for receiving a first PDCP (packet data convergence protocol) PDU (protocol data unit) and a first serial number from the mobile source base station, a receiving unit for receiving a second PDCP PDU from the mobile destination base station, a storing unit for storing a PDCP SDU corresponding to the first PDCP PDU and a PDCP SDU corresponding to the second PDCP PDU, and a reordering unit for sending stored PDCP SDU in sequence of serial numbers according to the first serial number and a second serial number, wherein the second PDCP PDU is generated according to the second serial number and the PDCP SDU transmitted to the mobile destination base station from the mobile source base station.

Description

Wireless communication system

Application for a patent for invention (the international application no: PCT/JP2007/059037 of the application to be original bill application number be 200780052592.X, the applying date: on April 26th, 2007, denomination of invention: base station, mobile radio station, communication system, sending method and method for reordering) divisional application.

Technical field

The present invention relates to wireless communication system.

Background technology

At present, the mobile communication system such as mobile phone start based on the business under the third generation mode of CDMA mode, but under 3GPP (third generation partner program), launch the discussion (non-patent literature 1) about the next generation mobile communication system that can carry out more high-speed communication (LTE:Long Term Evolution: Long Term Evolution).Mention here, except the high speed of transmission rate, cutting down transmission delay is also great problem.

In order to make transmission rate high speed and cut down transmission delay and carried out such research, that is: in LTE communication system, compared with system in the past, achieve the High Level of switching (Hand Over) method.In mobile communications, when mobile radio station moves in the communications, the conversion (switching) of the base station communicated can be carried out according to accepting state.Therefore, at a high speed/low delay communication, the High Level realizing switching is must be obligato.In LTE communication system, be basic with packet switching system, therefore switch (Hand Over) and just become Hand Hand Over.In Hand Hand Over, after the connection between the base station having cut off mobile radio station and mobile advance Serial Communication, carry out the connection between mobile radio station and mobile destination base station.In Hand Hand Over, owing to obtaining the system information of mobile destination base station before being about to switch, therefore, it is possible to switch in short time, but the Transmission state of user data can be there is in the handover.

Therefore, in order to reduce transmission delay, significantly, the disappearance that Transmission state and preventing is divided into groups in Transmission process is shortened.When there occurs grouping disappearance once break in the transmission in process, need to be resend by grouping end to end to recover, therefore transmission delay becomes greatly.

In addition, in the switching of LTE communication system, by following methodological standardization, described method is: by forward from moving source base station to mobile destination base station comprise the control information of issuing mobile radio station and be grouped in interior data, not from this moving source base-station transmission to the grouping of mobile radio station, carry out thus joining (non-patent literature 2).

Handing-over during switching

Handing-over key diagram when Figure 21 is switching.In Figure 21 (A), two base stations 1a, 1b (such as MME/SAE gateway) 2 of standing with higher level is connected.Mobile radio station 4 is present in the community 3a of base station 1a, currently communicates with base station 1a.In this condition, as shown in Figure 21 (B), perform switching when mobile radio station 4 moves towards the direction of base station 1b and enters in the 3b of community, the communication base station of mobile radio station is switched to base station 1b from base station 1a.Wherein, the base station of carrying out communicating before switching is called moving source base station (source base station), the base station switching laggard Serial Communication is called mobile destination base station (target BS).

2 groupings received of standing from higher level are kept in built-in buffer by moving source base station 1a, and send the grouping be kept in this buffer successively to mobile radio station 4.Therefore, when switching, there is the grouping storing and send to mobile radio station in both the buffers and not yet.In Figure 21 (B), store reception before switching in both the buffers and not to grouping n-2 ~ n that mobile radio station sends, need after handover these groupings to be sent to mobile radio station 4 from mobile destination base station 1b.Therefore, when switching sequence performs, moving source base station 1a will divide into groups n-2 ~ n forwarding (forwarding) to mobile destination base station 1b.By using this retransmission method, mobile destination base station 1b sends this grouping to mobile radio station 4 after the handover at once, therefore grouping can not occur and interrupt.So, can not occur to divide into groups end to end to resend, switching at a high speed can be performed.In addition, said n-2 ~ n is the numbering (sequence number) representing order of packets.

Switch

Figure 22 is the switching key diagram of LTE communication system, and Figure 23 is the switch step key diagram of imagination at present in LTE communication system.

To moving source base station 1, mobile radio station 4 notifies that needs carry out switchings HO (Hand Over) (1. measuring control) by measuring report (Measurement Report) (the reception status report from base station 1 and peripheral base station).

Target BS 1b (2.HO determines destination) is determined according to the content measuring report in moving source base station 1, and sends handover request (3.HO request) to this mobile destination base station 1b.Now, moving source base station 1a also sends the information (mobile radio station ID and QoS (Quality of Service: service quality) information etc.) etc. of mobile radio station.Mobile destination base station 1b carries out Call control (4. Call control) according to these information.

When mobile destination base station 1b allows access mobile radio station, reply handoff response (5.HO response) to moving source base station.Then, moving source base station 1a sends to mobile radio station 4 and switches instruction (6.HO instruction), and starts the handing-over of (forwarding of packets: forwarding) data (grouping) before and after this.

Receive the mobile radio station 4 switching instruction to guarantee to keep synchronous (7. synchronously guaranteeing) with mobile destination base station 1b by L1/L2 signaling, ensure that synchronously, send the report (8.HO completes) switched to mobile destination base station 1b.

Thus, the report switched sends to higher level to stand 2 (9.HO completes) by mobile destination base station 1b.Higher level stands 2 when receiving the report switched, packet transmission path is switched to mobile destination base station 1b (10. path switches) from moving source destination 1a, and completes response (11.HO completes response) to mobile destination base station 1b reply HO.Mobile destination base station 1b completes response according to HO and notifies that switching HO completes (12. resource release) to moving source base station 1a.Afterwards, the path (13. resources discharge) that moving source base station 1a and higher level stand between 2 is eliminated.

The order match control of grouping

In above-mentioned switching sequence performs, when there is forwarding of packets (forwarding), in the 1b of mobile destination base station, owing to standing 2 groupings entered and the grouping that causes this forwarding is jumped from higher level, thus sequence number disorder may be caused.If mobile destination base station 1b forwards grouping to mobile radio station 4 under the state of sequence number disorder, then mobile radio station can not by being correctly received sequentially grouping, and therefore communication quality worsens, and result causes cannot realizing high-quality communication before the handover.

At this, for LTE communication system, in base station and mobile radio station, profit keeps the order matching of dividing into groups with the following method.Figure 24 is the key diagram of the order coupling of this grouping, and mobile destination base station 1b forwards from moving source base station 1a the grouping of coming compared to the packet priority transmission received from higher level station, keeps the order matching of dividing into groups thus.

In fig. 24, before the handover, store grouping n-5 ~ n in the 1a of moving source base station, the grouping n-5 ~ n-2 in these groupings has been sent to mobile radio station 4, and n-1 and n that divide into groups not yet is sent to mobile radio station 4.In addition, grouping n-5 and n-3 in the grouping that mobile radio station sends is not moved station 4 and correctly receives (NACK), n-4 and n-2 that divide into groups then is normally received at (ACK).Therefore, grouping n-4, n-2 are kept in buffer BF1 by mobile radio station 4, and do not preserve grouping n-5 and n-3.

In this condition, when a switchover occurs, moving source base station 1a to mobile destination base station 1b forward (forwarding) be not moved grouping n-5 and n-3 that station 4 normally receives and not yet to grouping n-1 ~ n that mobile radio station 4 sends, mobile destination base station 1b by this packet memory in buffer BF.In addition, higher level stands and 2 sends to mobile destination base station 1b after handover and will issue two of mobile radio station 4 grouping m ~ m+1, mobile destination base station 1b by this packet memory in buffer BF.

When mobile destination base station 1b can communicate with mobile radio station 4, first preferentially send to mobile radio station 4 and forward next grouping n-5, n-3, n-1 ~ n from moving source base station 1b.Then, send and to stand the 2 grouping m ~ m+1 received from higher level.As shown in figure 25, mobile radio station 4 rearranges according to sequence number order grouping n-5, n-3, n-1 of receiving after grouping n-4, n-2 of receiving before switching and switching ~ n, m ~ m+1, and in order they is passed to upper layer.

The above is, by forwarding (forwarding), grouping n-5, n-3, n-1 ~ n is all forwarded (forwarding) to the situation of mobile destination base station 1b, but also exist and only forwarded grouping n-5, n-3, and there is situation about postponing in the forwarding of n-1 ~ n.Figure 26 is the key diagram of the order of packets coupling in this situation.Grouping n-5, n-3 that forwarding comes by mobile destination base station 1b and the grouping m ~ m+1 entered from higher level station are stored in buffer BF, but first preferentially send grouping n-5, n-3 of coming from moving source base station 1a forwarding to mobile radio station.Then, when postponing has appearred in the forwarding of grouping n-1, n of being undertaken by moving source base station 1a, mobile destination base station 1b monitors whether have passed through setting-up time (Waiting Time: stand-by period), when have passed through the stand-by period still not from moving source base station 1a forward divide into groups n-1, n time, be considered as forward terminate, send from higher level stand receive grouping m, m+1.In addition, after forwarding terminates, even if mobile destination base station 1b receives grouping n-1, n from moving source base station 1a, also this grouping can be abandoned.

Mobile radio station 4 performs the process (reordering) rearranged the grouping received by sequence number order.As shown in figure 27, mobile radio station 4 rearranges grouping n-5, n-3, m, m+1 of receiving after grouping n-4, n-2 of receiving before switching and switching by sequence number order, and in order they is passed to upper layer.

Protocol architecture

As mentioned above, in the switching of LTE communication system, the process of reordering of forwarding of packets (forwarding) and grouping is necessary technology.Here, the relation of these functions is described in detail.

Figure 28 is the key diagram of the protocol architecture represented between mobile radio station and network.Between the mobile stations and the base stations, PDCP (Packet Data Convergence Protocol: PDCP) layer, RLC (RadioLink Control: wireless spread-spectrum technology) layer and lower layer (MAC layer/physical layer MAC/PIIY) is at least provided with.MME/S-GW possesses packet routing function etc.

The major function of each agreement is as follows.

(1) PDCP: in PDCP layer, the header of bit protocol in transmitter side compression, and appended sequence number sends.At receiver side, sequence number is checked, carry out the waste treatment repeating to receive thus.Do not resend in PDCP layer.

(2) RLC:RLC layer has the layer resending function, new additional with from the sequence number in the different rlc layer of the sequence number added in the data of PDCP, and to send.Such as, when receive sequence number from PDCP be the data of n, this Data Segmentation is become many parts, to sequence number I (1), I (2), I (3) in each partition data respectively additional rlc layer ..., and send.Receiver side utilizes this sequence number I (), and what the normal reception/exception to transmitter side notification list registration certificate received sends to confirmation signal (Ack/Nack signal).If return Ack signal, then transmitter side abandons preserved data, and on the other hand, if return Nack, then transmitter side resends preserved corresponding data.

(3) lower layer

MAC:MAC layer is the layer data of rlc layer being carried out to multiplexing/separation.That is, at transmitter side, carrying out multiplexingly it can be used as transmission data to the data of rlc layer, at receiver side, is the data of rlc layer the reception data separating of MAC layer.

PIIY:PIIY layer is the layer wirelessly carrying out data transmit-receive between user terminal 4 and base station 1, and MAC layer data transaction is become wireless data, or converts wireless data to MAC layer data.

First the data sent to mobile radio station enter PDCP layer from upper layer (such as IP layer) and become PDCP SDU (Service Data Unit: service data unit), are then become PDCP PDU (Protocol Data Unit: protocol Data Unit) by additional header information (sequence number etc. of PDCP layer).

PDCP PDU is sent back to rlc layer and becomes RLC SDU, is then become RLC PDU by additional header information (sequence number etc. of rlc layer).RLC PDU through lower layer process and arrive the rlc layer of mobile radio station.In this rlc layer, remove header and again construct RLC SDU, in PDCP layer, then remove the header of PDCP PDU and become PDCP SDU, and being sent back to upper layer.

In this protocol architecture, for LTE communication system, in units of PDCP SDU, implement forwarding of packets, implement to reorder in units of PDCP PDU.In addition, when implementing to forward in units of PDCP SDU, not to header information such as the grouping appended sequence number in units of PDCP SDU, therefore this sequence number cannot be forwarded.Therefore, when implementing to forward in units of PDCP SDU, the header information such as the sequence number that add to also be forwarded.In addition, RLC SDU and PDCP PDU are in fact identical data, therefore in this manual as long as no being particularly limited to, just they are referred to as grouping, and when describing the numbering of this grouping, this numbering refers to the sequence number of PDCP PDU.

The action of moving source base station apparatus

The action flow chart of moving source base station apparatus when Figure 29 is switching.

Moving source base station 1a, when by measuring report and receiving received electric field strength etc. from user terminal 4 (step 101), judges whether that needs carry out switching HO (step 102), if do not need to carry out switching, turns back to initial point.

But when being defined as needs and switching, moving source base station 1a determines mobile destination base station 1b according to the content measuring report, sends handover request (step 103) to this mobile destination base station 1b.

Then, receive the handoff response (step 104) of sending from mobile destination base station 1b, carry out the forwarding (step 107) of packets remaining.

Afterwards, receive the resource release message (step 108) of sending from mobile destination base station 1b, perform resource release (step 109).

The action of mobile destination base station

The action flow chart of mobile destination base station when Figure 30 is switching.

Mobile destination base station 1b is when receiving HO request (comprising mobile radio station ID and QoS information etc.) (step 121) from moving source base station 1a, carry out Call control according to these information, judge whether to allow access mobile radio station (step 122).If do not allowed, then perform reprocessing (step 130), terminate switching controls.

On the other hand, when allowing access mobile radio station, HO response (step 123) is replied to moving source base station 1a.Then, mobile destination base station 1b will forward the packet memory come in both the buffers (step 124) from moving source base station 1a, and receives from mobile radio station 4 report (step 125) that HO completes.If receive the report that HO completes, then the report that HO completes by mobile destination base station 1b sends to higher level to stand 2 (steps 126).Higher level stands 2 when receiving the report switched, and packet transmission path is switched to mobile destination base station 1b from moving source base station 1a, replys HO complete response to mobile destination base station 1b.If mobile destination base station 1b stands from higher level and 2 receives HO and complete response (step 127), then from forwarding by mobile destination base station 1b the grouping come, it is preferentially sent to mobile radio station, after have sent this grouping, 2 groupings received (scheduling: step 128) of standing to mobile radio station transmission from higher level.In addition, with step 128 concurrently, mobile destination base station 1b to moving source base station 1a send resource release message (step 129), carry out reprocessing (step 130), terminate switching controls.In addition, the forwarding of packets undertaken by moving source base station 1a in the dispatch deal of step 128 occurs to postpone, mobile destination base station 1b monitors whether have passed through setting-up time (Waiting Time: stand-by period), when have passed through the stand-by period still do not forward divide into groups time, be considered as forwarding and terminate, send and to stand the grouping received, and after forwarding terminates from higher level, even if receive grouping from moving source base station 1a, also this grouping can be abandoned.

The action of mobile radio station

The action flow chart of mobile radio station when Figure 31 is switching.

The determination part of mobile radio station 4 is by measuring report to (steps 151) such as moving source base station notice received electric field strengths.Afterwards, wait for that the HO from moving source base station 1a indicates, when receiving HO instruction (step 152), guarantee to keep synchronous (step 153) with mobile destination base station 1b by L1/L2 signaling, ensure that synchronously, send the report (step 154) switched to mobile destination base station 1b, then, mobile radio station, when receiving grouping from mobile destination base station 1b, performs process (step 155 ~ 160) of reordering.

That is, the control part of mobile radio station is when receiving lower layer grouping from mobile destination base station 1b, constructs RLCSDU, is given by this RLC SDU (PDCP PDU) and reset prelude (step 155).Reset prelude checking sequence number and whether there is disappearance (step 156), if sequence number does not exist disappearance but continuous print, then this RLC SDU (PDCP PDU) is passed to upper layer (step 160) as PDCP SDU.On the other hand, if sequence number exists disappearance, then control part instruction is reset prelude and is preserved PDCP PDU.Thus, reset prelude and preserve PDCP PDU (step 157), and check whether and receive sequence number continuous print RLC SDU (PDCP PDU) (step 158).If receive sequence number continuous print RLC SDU (PDCP PDU), then this RLC SDU (PDCP PDU) is passed to upper layer as PDCP SDU, and kept PDCP PDU is passed to upper layer (step 160).

In addition, in step 158, if do not receive sequence number continuous print RLC SDU (PDCP PDU), then monitor and whether have passed through the scheduled time (step 159), if not yet after a predetermined time, then repeat step 157 and process afterwards, and if have passed through the scheduled time, even if then sequence number is discontinuous, also preserved PDCP PDU to be passed to upper layer (step 160).

Problem

But, when performing the forwarding of packets with switching in LTE communication system, there is following problem.That is, when a handover is performed, as mentioned above, in LTE communication system, perform the handing-over of the moving station number certificate be retained in the 1a of moving source base station, and produce the forwarding of packets (forwarding) with handing-over.But, in above-mentioned switching controls, when the value of the stand-by period (Waiting Time) of mobile destination base station 1b is less, although exist and not yet forward all groupings, mobile destination base station 1b just starts to transmit the grouping received from higher level station, thus abandons the problem of the grouping not yet forwarded.On the other hand, when the value of stand-by period is larger, mobile destination base station 1b was not transmitting the grouping received from higher level station before the stand-by period, thus there is the problem that transmission delay occurs.That is, in switching controls in the past, the problem of communication delay increase and throughput degradation can be there is, high-quality communication cannot be guaranteed afterwards before the handover.

As the 1st prior art, there is the method (with reference to non-patent literature 3) notifying the last grouping (Last Packet) forwarded from moving source base station to mobile destination base station.When forward occur postponing, the sequence number of the grouping received from higher level station can be set to the sequence number+1 of last grouping and carry out hop transmission by the mobile destination base station of notified last grouping.In addition, the sequence number of grouping that forwarding can come by mobile destination base station and the sequence number of last grouping compare, and force thus to terminate waiting timer (Waiting Timer), thus can detect the end of forwarding in the best timing.But when having abandoned last grouping in repeating process, mobile destination base station cannot reliably detect last grouping.

In addition, as the 2nd prior art, there is such mobile communication system: when this mobile communication system is used for switching between the base station of just carrying out high speed packet communication, the HRPD (high rate packet data) realizing not occurring loss of data forwards (with reference to patent documentation 1).In this mobile communication system, when a switchover occurs, the base station of handover source forwards (forwarding) grouped data to handover destination base station.But this technology is not improved to be increased and throughput degradation by the communication delay caused that reorders of mobile radio station.

In addition, as the 3rd prior art, there is such method: in mobile destination base station, do not wait for the arrival of forwarded grouping, but jumpily transmit and to stand the grouping (with reference to patent documentation 2) that transmission comes from higher level.In the method, by distinguishing the grouping received from moving source base station and the grouping received from higher level station, the hop transmission divided into groups can be realized.But, need the function that two sequential controls are set in the mobile stations, cause it to control to become complicated.

By upper, the object of the invention is to, (such as, the device that to mobile destination base station send data (grouping) different from moving source base station) is transferred to mobile destination base station by standing from higher level grouping will be transferred to mobile radio station rapidly.

Another object of the present invention is to, even if the grouping forwarded from moving source base station mixes with the grouping transmitted of standing from higher level, also can by get rid of from the object of sequential control this from higher level stand transmission come grouping, only utilize thus a sequential control function can correctly to forward come grouping reorder.

In addition, another object of the present invention can be positioned, and provides the middle not items disclosed in prior art recorded such as embodiment.Preferably, such item is the necessary item of effect that cannot obtain to obtain prior art.

Non-patent literature 1:3GPP, " Requirements for Evolved UTRA (E-UTRA) and EvolvedUTRAN (E-UTRAN), " TR25.913 V7.3.0, Release 7, March 2006.

Non-patent literature 2:3GPP, " Evolved Universal Terrestrial Radio Access (E-UTRA) andEvolved Universal Terrestrial Radio Access Network (E-UTRAN); " TS36.300, Release8, V8.0.0, April 2007.

Non-patent literature 3:Samsung, " Method to release resources at source ENB duringhandover, " R3-061032, RAN3#53, September 2006.

Patent documentation 1: Japanese Unexamined Patent Publication 2004-282652 publication

Patent documentation 2: No. 2006-086537, Japanese Patent Application

Summary of the invention

Wireless communication system of the present invention is such communication system: send the data (such as dividing into groups) that addition of the numbering of order of representation from mobile destination base station to mobile radio station, and sequentially rearrange data by number in the mobile stations.Communication system of the present invention has: this wireless communication system has: moving source base station, mobile destination base station and mobile radio station, described mobile radio station has: receiving element, it receives PDCP PDU and a First ray number from described moving source base station, the 2nd PDCP PDU is received from described mobile destination base station, wherein, the 2nd PDCP PDU the second sequence number of utilizing described moving source base station to forward to described mobile destination base station and PDCP SDU generate; Memory cell, it stores the PDCP SDU corresponding with a described PDCP PDU and the PDCP SDU corresponding with described 2nd PDCPPDU; And the unit that reorders, it, according to this First ray number and the second sequence number, sequentially sends the PDCP SDU stored by number.

Accompanying drawing explanation

Fig. 1 is the key diagram of the 1st embodiment.

Fig. 2 is the form example that PDCP PDU divides into groups.

Fig. 3 is the key diagram of packet transaction of PDCP layer before switching and rlc layer.

Fig. 4 is the key diagram of packet transaction of PDCP layer after switching and rlc layer.

Fig. 5 is the structure chart of base station.

Fig. 6 is the structure chart of mobile radio station.

Fig. 7 is the action flow chart of the mobile destination base station of the 1st embodiment.

Fig. 8 is the flow chart of the moving source base station of the 1st embodiment.

Fig. 9 is the action flow chart of the mobile radio station of the 1st embodiment.

Figure 10 is the handling process that reorders of mobile radio station.

Figure 11 is the key diagram of the 2nd embodiment.

Figure 12 is the form example that PDCP PDU divides into groups.

Figure 13 be switch after PDCP layer and rlc layer packet transaction key diagram (one of).

Figure 14 is the key diagram (two) of the packet transaction of PDCP layer after switching and rlc layer.

Figure 15 is the action flow chart of the mobile destination base station of the 2nd embodiment.

Figure 16 is the action flow chart of the mobile radio station of the 2nd embodiment.

The sequence number of PDCP PDU to be attached after corresponding PDCP SDU data and to be carried out the example that notifies by datum plane (U-Plane) by Figure 17.

The sequence number SN of PDCP PDU to be attached after corresponding PDCP SDU data and to be notified by U-Plane by Figure 18, simultaneously by the example of C-plane notification sequence number.

Figure 19 is the transfer sequence step of Figure 18.

Figure 20 is the example of the situation that there are not the PDCP SDU data that will forward completely.

Handing-over key diagram when Figure 21 is switching.

Figure 22 is the switching key diagram of LTE communication system.

Figure 23 is switch step key diagram contemplated at present in LTE communication system.

Figure 24 is the 1st key diagram of the process of reordering of mobile radio station.

Figure 25 is the 2nd key diagram of the process of reordering of mobile radio station.

Figure 26 is the 3rd key diagram of the process of reordering of mobile radio station.

Figure 27 is the 4th key diagram of the process of reordering of mobile radio station.

Figure 28 is the key diagram of the protocol architecture represented between mobile radio station and network.

The action flow chart of moving source base station apparatus when Figure 29 is switching.

The action flow chart of mobile destination base station when Figure 30 is switching.

The flow chart of mobile radio station when Figure 31 is switching.

Embodiment

(A) principle of the present invention

In the present invention, its problem is solved by enabling base station and mobile radio station perform following two process.

Process 1: after handover, owing to there occurs delay from the data retransmission of moving source base station, therefore do not wait for the reception of these data and transmit the data that (hop transmission) receive from higher level's machine of standing, in this case, making mobile radio station can identify these data is hopped datas, and performs hop transmission.That is, be that the identifying information of hopped data is included in these data by being used for identifying, or this identifying information is attached in these data, or this identifying information is mapped with these data, and such as utilize control channel to send.

Process 2: mobile radio station when detect there occurs hop transmission, this hopped data is not considered as the object that reorders, is preserved in both the buffers, wait for the arrival of data forwarded from moving source base station.That is, use identifying information to distinguish and forward the data come and the data of sending without moving source base station from moving source base station, rearrangement sequence of going forward side by side.

In the conventional method, when the data retransmission (forwarding) from moving source base station to mobile destination base station there occurs delay, wait for mobile radio station and send the data being transferred to mobile destination base station from higher level station.Therefore, due in the arrival waiting for these data before the stipulated time (Waiting Time: stand-by period), thus the problem that communication delay increase and throughput degradation occur will be there is.But, as mentioned above, if carry out the hop transmission of data, even if then when data retransmission (forwarding) occurs to postpone, also the data received from higher level station can be transferred to mobile radio station rapidly, thus, reduce communication delay.Therefore, compared with the conventional method, the communication quality switching front and back can be guaranteed in high quality.

(B) the 1st embodiment

Fig. 1 is the key diagram of the 1st embodiment, and it carrys out the explanation of the situation row of additional sequence information to be grouped into unit, but also can be the data of prescribed level.

Be set to before the handover, store grouping n-5 ~ n in the 11a of moving source base station, the grouping n-5 ~ n-2 in these groupings has been sent to mobile radio station 14, and n-1 and n that divide into groups is not sent to mobile radio station 14.Such as, be that therefore these groupings n-1 and n is not sent to mobile radio station 14 because grouping n-1 and n just arrives after cutting off the radiolink between moving source base station 11a and mobile radio station 14.In addition, grouping n-5, the n-3 be set in the grouping sent to mobile radio station is not moved station 14 and correctly receives (NACK), and divide into groups n-4, n-2 are received normally (ACK).Therefore, mobile radio station 14 preserves grouping n-4, n-2, and does not preserve grouping n-5, n-2.

In this condition, when a switchover occurs, moving source base station 11a forwards (forwarding) to mobile destination base station 11b and is not moved grouping n-5 and n-3 that station 14 normally receives and grouping n-1, n of not sending.Below illustrate when grouping is forwarded, but be not limited to such example.

In addition, higher level stands and 2 sends to mobile destination base station 11b after handover and will issue two of mobile radio station grouping m ~ m+1.In addition, if the forwarding (forwarding) of grouping n-5 ~ n there occurs delay.

If dividing into groups stands from higher level before n-5, n-3, n-1 ~ n 2 receives grouping m, m+1 to mobile destination base station 11b forwarding from moving source base station 11a, then to grouping m, m+1 additional hops identification code F that this receives from higher level station, and first they are sent (hop transmission) to mobile radio station 14.

The grouping that addition of jump identification code F received from base station is saved in buffer BF2 by mobile radio station 14, and they is discharged outside the object of process that reorders.(A) of Fig. 1 represents that mobile radio station 14 preserves grouping m, m+1 in buffer BF2, and in buffer BF1, preserve the state of grouping n-4, n-2 of receiving before the handover.

Then, mobile destination base station 11b sends to mobile radio station and forwards next grouping n-5, n-3, n-1 ~ n from moving source base station 11a.These groupings n-5, n-3, n-1 ~ n received from mobile destination base station 11b is kept in buffer BF1 by mobile radio station 14, carry out the process of reordering (with reference to Fig. 1 (B)) of these groupings received after handover and grouping n-4, n-2 of receiving before the handover, and according to serial number order, grouping is passed to upper layer.In addition, when have passed through the stipulated time do not receive the grouping of serial number yet time, terminate to reorder process, will hereto to receive and the grouping rearranged passes to upper layer.

In addition, when forwarding, all groupings can be forwarded from moving source base station to mobile destination base station, also can only forward a part of data (user data part) comprised in grouping.Preferably, to forwarding data additional sequence information.

In addition, in FIG, sequence number (order information) m, m+1 are distributed to and has carried out the grouping of hop transmission, but mobile destination base station 11b can distribute arbitrary sequence number, the numbering repeated with the sequence number added the grouping forwarded can also be added, in addition, also unduplicated numbering can be adopted.

Jump identification code

As the example to grouping additional hops identification code F, employ " type " field of 3 bits comprised in the header of PDCP PDU.That is, be jump identification code F by new type number definition in this " type " field, and this type numbering is added to the grouping of hop transmission.Fig. 2 is the form example of PDCP PDU, and (A) is the form example without header, and (B) is the form example of the sequence number not adding PDCP PDU, and (C) and (D) is the form example of the sequence number that addition of PDCPPDU.In the form of (C) and (D), in header HD, define type field and PID field, represent the classification of PDCP PDU by type field.PID field is the field of the compression classification represented for the data comprised in Data portion.In type field, define " type=000 " and " type=001 ", and do not specify and do not use " type=010 ~ 111 ".Therefore, such as, utilize " type=010 ", as type numbering (jump identification code) for identifying the PDCP PDU having carried out hop transmission.

PDCP layer before and after switching and the process of rlc layer

Fig. 3 is the key diagram of packet transaction of PDCP layer before switching and rlc layer.Grouping n-5 ~ the n-2 of PDCP layer stores in both the buffers ((A) of Fig. 3) by moving source base station 11b, as shown in (B), in rlc layer, packet fragmentation is become multiple data, for each partition data add rlc layer sequence number I, I+1, I+2 ..., I+6, then send to mobile radio station 14.Mobile radio station 14 carries out the sequential control for PDCP layer before the handover in rlc layer.In figure 3, be set to mobile radio station 14 and normally do not receive partition data I, I+4, I+5, that is, divide into groups n-5, n-3, but normally have received grouping n-4, n-2.

Fig. 4 is the key diagram of packet transaction of PDCP layer after switching and rlc layer, and particularly illustrates the treatment state of PDCP layer and rlc layer.In addition, although mobile radio station 14 is the sequential controls carried out in rlc layer before the handover for PDCP layer, regulation carries out initialization to rlc layer after handover.Therefore, PDCP layer is transferred in the process of sequential control, and mobile radio station 14 performs switching sequence in PDCP layer.

Mobile radio station 14 starts timer to judge the end of reordering when reordering.

Grouping m, m+1 due to 2 receptions of standing from higher level take the lead in arriving, and therefore mobile destination base station 11b is to this grouping m, m+1 additional hops identification code F, and is first transmitted (hop transmission) to mobile radio station 14.The grouping that addition of jump identification code F received from base station is kept in buffer BF2 by mobile radio station 14, and they is got rid of outside the object of process that reorders.Afterwards, mobile radio station 14 to reorder process to grouping n-5, n-3, n-1 of receiving from mobile destination base station 11b ~ n and grouping n-4, n-2 of receiving before handover, and passes to upper layer.

In addition, when timer have passed through stipulated time T _mtime, mobile radio station 14 terminates to reorder process, even if grouping exists disappearance, also still the grouping received is sent back to upper layer.

Window control

Guard against the situation of the data of more than the data volume that can allow in having arrived, mobile radio station 14 generates the window of buffer size in inside, and carries out following window control when reordering process.In the example in fig. 4, the left end of window for time initial expect the numbering n-5 that arrives, the numbering n-2 of right-hand member for being determined by the data volume that can allow (window buffer size) of window.Mobile radio station is not to the grouping application window process that addition of jump identification code F.

Under initial condition (Window state (0)), when mobile radio station 14 receive expected grouping (n-5) go forward side by side the process of rearrangement sequence time, Window state is as shown in (1), therefore, mobile radio station forwards to upper layer the grouping (n-5) expected and divides into groups (n-4) with its continuous print.Then, the state shown in (2) that Window state becomes, when mobile radio station 14 receives expected grouping (n-3) in this condition and carries out reordering process, the state shown in (3) that Window state becomes.Therefore, mobile radio station forwards to upper layer the grouping (n-3) expected and divides into groups (n-2) with its continuous print.Then, the state shown in (4) that Window state becomes, mobile radio station 14 waits for the reception of grouping (n-1), n in this condition, if at setting-up time T _mreceive grouping (n-1), n, then they are transmitted to upper layer.But, if at setting-up time T _mduring in do not receive grouping (n-1), n, then mobile radio station 14 is by being kept at the grouping m in buffer BF2 and forwarding of packets afterwards to upper layer, transfers to the usual control before switching.As mentioned above, by jump grouping is performed above-mentioned window control with foreclosing, the process of reordering for grouping n-5 ~ grouping n can be performed.

In addition, in window control, mobile radio station 14, when receiving the grouping of the sequence number less than the sequence number of window left end, abandons this grouping.In addition, mobile radio station 14 is when receiving the grouping of the sequence number larger than the sequence number of window right-hand member, the sequence number of this window right-hand member is set to the sequence number of this grouping, the sequence number of window left end is changed to the numbering determined by window buffer size, the reception of ejecting in this window ranges grouping is passed to upper layer simultaneously.

If also apply window treatments to jump grouping, then, when receiving grouping m, it is n-2 that Window state such as becomes window left end, and window right-hand member is m.In this case, mobile radio station abandons the reception of grouping n-5, the n-3 not yet received, and is transmitted to upper layer by receiving grouping n-4, n-2.Then, the sequence number of window right-hand member is set as m, the sequence number of window left end is set as the numbering n-1 determined by window size, afterwards wait for grouping n-1, grouping n, grouping n+1 ..., grouping m-1 arrival.But among this, grouping n+1 ~ grouping m-1 is in fact non-existent grouping, therefore, has vainly waited for these receptions of dividing into groups, has caused packet transaction generation problem.

The structure of base station

Fig. 5 is the structure chart of base station, shows buffer unit, scheduling unit, receiving and transmitting part and control part.

Buffer unit 21 is for storing the grouping entered from higher level station and the memory forwarding the grouping come from adjacent base station (moving source base station).In the figure, be physically provided with two buffers 21a, 21b, but also can adopting a memory is physically only being set, carrying out splitting the apparatus structure utilized from software.

Scheduling unit 22 selects the mobile radio station carrying out wireless transmission from the multiple mobile radio stations communicated, and takes out the grouping of this base station stored in both the buffers, sends back to receiving and transmitting part.Receiving and transmitting part 23 is encoded to the grouping come from scheduling unit transmission, modulation treatment, and utilizes wireless mode to carry out actual transfer of data.In addition, receive the control signal of sending from mobile radio station and various data and demodulation is carried out to it.

Control part 24 has buffer management portion 24a, HO control part 24b and measures control part 24c.Buffer management portion 24a manages the various groupings be stored in buffer 21.If perform data handing-over when switching, then at least will by the forwarding of packets not obtaining normal confirmation of receipt (ACK) that is stored in buffer 21b to mobile destination base station 11b.On the other hand, the arrival forwarding the grouping come from moving source base station 11a is being caused to there occurs delay due to data handing-over, thus hop transmission from higher level stand 2 receive grouping, charge to " type=010 " in the type field of the header divided into groups in this jump.

HO control part 24b performs the switching controls utilizing Figure 23 to illustrate, measures control part 24c and collects the various mensuration information of sending from mobile radio station, the wireless quality CQI (Channel Quality Information) etc. of such as mobile radio station.

The structure of mobile radio station

Fig. 6 is the structure chart of mobile radio station, shows receiving and transmitting part 31, buffer unit 32, resets prelude 33 and control part 34.Receiving and transmitting part 31 and the receiving and transmitting part of base station carry out dividing into groups and the transmitting-receiving of control information.Buffer unit 32 is not when constructing RLC PDU according to the lower layer grouping received, be saved in till can constructing this RLC PDU, when RLC PDU constructs successfully, remove header, pass to as RLC SDU (PDCP PDU) and reset prelude 33.Reset prelude 33 to have for rearrange PDCP PDU according to sequence number order and passed to the function of upper layer.Resetting prelude 33 when detecting that disappearance occurs the sequence number of PDCP PDU, PDCP PDU being afterwards kept in internal memory, until receive sequence number continuous print PDCP PDU.But, when have passed through that the stipulated time, this PDCP PDU did not still arrive, resetting prelude and stopping reordering process, stored all PDCP PDU are passed to upper layer.In addition, resetting prelude 33 when reordering, carrying out window control, making handled data volume be no more than allowance.

Control part 34 has determination part 34a, reorder management department 34b and resend management department 34c.Determination part 34a measures the various mensuration information sending to base station.Such as, the wireless quality CQI (ChannelQuality Information) of mobile radio station is measured.The 34b reorder portion of management department 33 that reorders controls, and when resetting PDCP PDU that prelude 33 preserves and there occurs numbering disappearance, the arrival of numbering continuous print PDCP PDU is waited in instruction.In addition, when the arrival stand-by period of this grouping have passed through the stipulated time, instruction is reset prelude 33 and is stopped reordering, and the header of all PDCP PDU preserved is removed in instruction, pass to upper layer as PDCP SDU, thus be in the state that can receive new PDCP PDU.Then, the maximum sequence number received so far is set as the sequence number of window right-hand member by the management department 34b that reorders, and by considering that window size decides and sets the sequence number of window left end.Here, if exist sequence number less than the sequence number of window left end reception grouping, then direct by this forwarding of packets to upper layer.Resending management department 34c when resending control, resending request signal by receiving and transmitting part to base station transmission according to the path represented by dotted line.

The action of mobile destination base station

Fig. 7 is the action flow chart of the mobile destination base station of the 1st embodiment.

The switch control portion 24b of mobile destination base station 11b is when receiving HO request (comprising mobile radio station ID and QoS information etc.) (step 201) from moving source base station 11a, carry out Call control according to these information, judge whether to allow access mobile radio station (step 202).If do not allowed, carry out reprocessing (step 213), and terminate switching controls.

On the other hand, switch control portion 24b, when allowing access mobile radio station, replys HO request response (step 203) to moving source base station 11a.Then, mobile destination base station 11b waits for from moving source base station 11a and forwards the grouping of coming, and afterwards, buffer unit 21 is stored (step 204) when receiving and forwarding from moving source base station 11a the grouping come.

In this condition, switch control portion 24b is when receiving the report that HO completes (step 205) from mobile radio station 14, superior station 12 sends the report (step 206) that HO completes.When higher level stands in and receives the report switched, the transmission path of grouping is switched to mobile destination base station 11b from moving source base station 11a, and completes response to mobile destination base station 11b reply HO.The switch control portion 24b of mobile destination base station 11b 12 receives (step 207) when HO completes response standing from higher level, starts to send grouping (step 208) to scheduling unit 22 instruction.

Thus, scheduling unit 22 checks whether that needs carry out grouping hop transmission (step 209), if do not needed, then preferentially sends to mobile radio station 14 and forwards from moving source base station 11a the grouping (step 210) of coming.But if occur postponing from the forwarding of the grouping of moving source base station 11a thus need to carry out grouping hop transmission, then scheduling unit 22 performs the hop transmission of 12 groupings received of standing from higher level.

When performing hop transmission, the classification number that will carry out the type field of the grouping of hop transmission is set as 010 (type=010), making mobile radio station 14 can identify this grouping is hop transmission grouping (step 211), then transmits this grouping (step 210) to mobile radio station 14.

With process concurrently above, switch control portion 24b to moving source base station 11a send resource release message (step 212), perform reprocessing (step 213), terminate switching controls.

The action of moving source base station

Fig. 8 is the device action flow chart of the moving source base station of the 1st embodiment.

In fig. 8, the mensuration control part 24a of moving source base station 11a is when receiving receiving status information by measuring report from mobile radio station 14 (step 251), judge whether that needs carry out switching (HandOver:OH) (step 252) according to this receiving status information, if do not need to switch, then turn back to initial point.

But when being defined as needs and carrying out switching HO, switch control portion 24b determines mobile destination base station 11b according to the content measuring report, sends handover request (step 253) to this mobile destination base station 11b.

Then, when receiving the HO response message sent from mobile destination base station 11b (step 254), HO control part 24b sends HO Indication message (step 255) to mobile radio station 14, and instruction cache management portion 24a remains in the grouping in buffer 21 to mobile destination base station 11b forwarding (forwarding of packets).Thus, 24a path by a dotted line in cache management portion forwards the grouping not being sent to mobile radio station 14 or the grouping (NACK grouping) (step 256) be not received normally that exist in (forwarding) buffer 21b to mobile destination base station 11b.Afterwards, receive the resource release message (step 257) of sending from mobile destination base station 11b, perform resource release (step 258).

The action of mobile radio station

Fig. 9 is the action flow chart of mobile radio station.

The determination part 34a of mobile radio station 14 notifies (steps 271) such as accepting states to moving source base station 11a by measuring report.Afterwards, control part 34 waits for the HO Indication message sent from moving source base station 11a, when receiving HO Indication message (step 272), guarantee to keep synchronous (step 273) with mobile destination base station 11b by L1/L2 signaling, after ensure that synchronously, send the report (step 274) switched to mobile destination base station 11b.Then, control part 34 checks that whether received grouping is for jumping over grouping, in other words, check whether the grouping (step 275) for type=010, if jump grouping, then to be got rid of outside the object that reorders and to be kept in buffer 32, after setting-up time, remove header and be set to that PDCP SDU grouping passes to upper layer (step 276).On the other hand, if not jump grouping, then perform and reorder, rearrange in order, then pass to upper layer (step 277) as PDCP SDU.

Figure 10 is the handling process that reorders of mobile radio station.

When the receiving and transmitting part 31 of mobile radio station receives lower layer grouping from mobile destination base station 11b (step 301), can the management department 34b that reorder checks construct RLC PDU (step 302), when not constructing, check whether and have passed through setting-up time (step 303), not yet through setting-up time, the grouping of this lower layer is kept in buffer 32 (step 304), carries out step 301 and process afterwards thereof.When have passed through setting-up time and still can not construct RLC PDU after receiving lower layer grouping, from buffer, delete lower layer grouping (step 305).

On the other hand, when the lower layer grouping received can be used in step 302 to construct RLC PDU, this RLC PDU is passed to as RLC SDU (PDCP PDU) and resets prelude 33 (step 306).Reset prelude 33 when receiving RLC SDU (PDCP PDU), check whether to there is sequence number disappearance (step 307), if sequence number does not exist disappearance but continuous print, then the header deleting this RLC SDU (PDCP PDU) is set into PDCP SDU and passes to upper layer (step 311).But if sequence number exists disappearance, then the management department 34b that reorders indicates rearrangement prelude 33 to make it preserve PDCP PDU (step 308).Thus, reset prelude 33 and preserve PDCP PDU, and check whether and receive sequence number continuous print RLC SDU (PDCP PDU) (step 309).If receive sequence number continuous print RLC SDU (PDCP PDU), then this RLC SDU (PDCP PDU) is passed to upper layer as PDCP SDU, and preserved PDCP PDU is passed to upper layer (step 311).

In addition, if do not receive sequence number continuous print RLC SDU (PDCP PDU) in a step 309, then monitor and whether have passed through scheduled time T _m(step 310), if T not yet after a predetermined time _mthen repeat step 308 and process afterwards thereof, and when have passed through setting-up time T _mtime, even if sequence number is discontinuous, also preserved PDCPPDU is passed to upper layer (step 311).

As mentioned above, according to the 1st execution mode, the grouping that 12 to mobile destination base station 11b transmission of standing from higher level come can be divided into groups as jump, is transferred to mobile radio station 14 when not waiting for, thus the time of delay of data can be eliminated, the throughput of entire system can be improved.In addition, mobile radio station 14 gets rid of grouping of jumping from the object of control (sequential control) of reordering, and carries out sequential control, according to sequence number order, grouping is passed to upper stage arrangement to the grouping outside grouping of jumping.Its result, even if mobile radio station only has a sequential control function, also can carry out the sequential control of dividing into groups.

(C) the 2nd embodiment

In the 1st embodiment, mobile radio station 14 is at setting-up time T _mperiod carries out process of reordering, when have passed through setting-up time T _mtime, terminate to reorder process (step 310 in Figure 10).Therefore, mobile radio station 14 after receiving all groupings forwarded from moving source base station 11a to mobile destination base station 11b, if still without setting-up time T _m, then continue execution and to reorder process.At this, in the 2nd embodiment, the last grouping of reordering in handling object can be identified in order to make mobile radio station 14, mobile destination base station 11b is to specifying grouping (last grouping) additional discriminators and being transferred to mobile radio station, mobile radio station 14 when receiving this last grouping, even if not yet through setting-up time T _malso process of reordering can be terminated immediately.

Figure 11 is the key diagram of the 2nd embodiment, is set to before the handover, stores grouping n-5 ~ n in the 11a of moving source base station, and the grouping n-5 ~ n-2 in these groupings has been sent to mobile radio station 14, but grouping n-1 and n is not sent to mobile radio station 14.Such as, because grouping n-1 and n just arrives after cutting off the radiolink between moving source base station 11a and mobile radio station 14, therefore these groupings n-1 and n is not sent to mobile radio station 14.In addition, grouping n-5, the n-3 be set in the grouping sent to mobile radio station is not moved station 14 and correctly receives (NACK), and divide into groups n-4, n-2 are received normally (ACK).Therefore, mobile radio station 14 preserves grouping n-4, n-2, and does not preserve grouping n-5, n-3.

In this condition, when a switchover occurs, moving source base station 11a forwards (forwarding) to mobile destination base station 11b and is not moved grouping n-5 and n-3 that station 14 normally receives and grouping n-1, n of not being sent to.In addition, higher level stand 12 after handover to mobile destination base station 11b send two grouping m ~ m+1.Wherein, if the forwarding (forwarding) of grouping n-5 ~ n there occurs delay.

If dividing into groups stands from higher level before n-5, n-3, n-1 ~ n 12 receives grouping m, m+1 to mobile destination base station 11b forwarding from moving source base station 11a, then to grouping m, m+1 additional hops identification code F received from this higher level station, and first they are sent (hop transmission) to mobile radio station 14.The grouping that addition of jump identification code F received from base station is saved in buffer BF2 by mobile radio station 14, and they is got rid of from the object of process of reordering.(A) of Figure 11 represents that mobile radio station 14 preserves grouping m, m+1 in buffer BF2, and in buffer BF1, preserve the state of grouping n-4, n-2 of receiving before the handover.

Mobile destination base station 11b have passed through scheduled time T _wmobile radio station is sent to by forwarding the grouping come, and if have passed through the stand-by period, even if the grouping then receiving forwarding next also can be abandoned till (being called Waiting Time (stand-by period)).Therefore, mobile base station 11b forwards from moving source base station 11a grouping n-5, n-3, the n-1 of coming receiving before the stand-by period, and to be kept in buffer BF and it is transferred to mobile radio station one by one.Further, be located at and receive grouping n and the stand-by period is then during stage being not yet transferred to mobile radio station from moving source base station 11a.In this case, mobile destination base station 11b is the identifier (L) forwarding the last grouping come to grouping n additional representation, and is transferred to mobile radio station 14.

Grouping n-5, n-3, n-1, n of receiving from mobile destination base station 11b are kept in buffer BF1 by mobile radio station 14, as shown in Figure 11 (B), process of reordering is performed to grouping n-4, n-2 of receiving before these groupings and switching, rearranges.In addition, when identifier (L) being added to grouping n being detected, being judged as forwarding and terminating, even if the setting-up time T reordered _mnot yet then, also the grouping of having reordered is passed to upper layer, terminate to reorder process.

The above is stand-by period situation then before transmission grouping n, but also there is stand-by period situation then in the stage after grouping n is transferred to mobile radio station.In this case, mobile destination base station 11b is identifiers (L) of last grouping to the 12 grouping m+2 additional representation received of standing from higher level, and is transferred to mobile radio station 14.The mobile radio station 14 receiving the last grouping that addition of this identifier is judged as forwarding and terminates, even if the setting-up time T reordered _mnot yet then also can terminate process of reordering immediately.

In addition, although have received grouping n-3 by forwarding, but also exist in stand-by period in the stage situation then not receiving grouping n-1, n.In this case, mobile destination base station 11b is the identifier (L) of last grouping to grouping n-3 additional representation, and is transferred to mobile radio station 14.Mobile radio station 14 detects the last grouping that addition of this identifier (L) and terminates process of reordering.

Last packet identification code L

When being last identifier (last packet identification code) to grouping additional representation, use " type " field of 3 bits comprised in the header of PDCP PDU.That is, in this " type " field, by new type number definition be last packet identification code L, and this type numbering is distributed to the grouping sent at first after the stand-by period.Figure 12 is the form example of PDCP PDU, and (A) is the form example without header, and (B) is the form example of the sequence number not adding PDCP PDU, and (C) and (D) is the form example of the sequence number that addition of PDCP PDU.In the form of (C) and (D), in header HD, define type field and PID field, represent the classification of PDCP PDU by type field.In type field, define " type=000 " and " type=001 ", and do not specify and do not use " type=010 ~ 111 ".Therefore, such as, utilize " type=011 ", as No. type for being identified in PDCP PDU grouping (last grouping) sent at first after the stand-by period.

The process of PDCP layer and rlc layer

Figure 13, Figure 14 are the key diagrams of packet transaction of PDCP layer after switching and rlc layer.

Figure 13 represents that grouping n that subtend mobile radio station transmits addition of the situation of last packet identification code L.Mobile radio station 14 starts timer to judge the end of reordering when reordering.Here, by setting-up time T _mwhen being set to larger value, with grouping n be whether forwarded last grouping independently, proceed process of reordering, at setting-up time T _mupper layer can not will be packeted back to then.But, in the 2nd embodiment, mobile radio station 14 addition of grouping n (the last grouping) of last packet identification code L during receiving, terminating immediately to reorder, all PDCP PDU packeted back to upper layer.

In addition, guard against the situation of the data of more than the data volume that can allow in having arrived, mobile radio station 14 carries out window control when reordering.The left end of window by the numbering n-5 that arrives of expectation, the right-hand member of window is the value of the upper limit as the data volume that can allow (is n) in figure.But, as described in Example 1, the grouping application window process not to " type=010 ".By this process, reordering for grouping n-5 ~ grouping n can be performed.

Figure 14 represents the situation that grouping m+2 be addition of to last packet identification code L.Mobile radio station 14 when receive grouping m+2 (last grouping) when, even if setting-up time T _mnot yet then, also can terminate immediately to reorder, all PDCP PDU received are packeted back to higher level's layer.In addition, window control is performed in the same manner as Figure 13.

The action of mobile destination base station

Figure 15 is the action flow chart of the mobile destination base station of the 2nd embodiment, gives identical label to the step identical with the step in Fig. 7 of the 1st embodiment.Base station in 2nd embodiment, mobile radio station have the structure shown in Fig. 5, Fig. 6.

The switch control portion 24b of mobile destination base station 11b, when receiving HO request (comprising mobile radio station ID and QoS information etc.) from moving source base station 11a, carries out Call control according to these information, judges whether to allow access mobile radio station.If do not allowed, then perform reprocessing, then terminate switching controls (step 201 ~ 202,213).

On the other hand, when switch control portion 24b allows access mobile radio station 14, reply HO request response to moving source base station 11a, and start to carry out timing to the elapsed time.Then, mobile destination base station 11b waits for from moving source base station 11a and forwards the grouping of coming, and by this packet memory (step 203 ~ 204) in buffer unit 21.

In this condition, switch control portion 24b is when receiving the report that HO completes from mobile radio station 14, the report completed by HO sends to higher level to stand 12 (step 205 ~ 206).Higher level stands 12 when receiving the report switched, and packet transmission path is switched to mobile destination base station 11b from moving source base station 11a, replys HO complete response to mobile destination base station.The switch control portion 24b of mobile destination base station 11b is when receiving HO and completing response from higher level station, instruction scheduling unit 22 starts to send grouping (step 207 ~ 208).

Then, scheduling unit 22 monitors whether the elapsed time has exceeded setting-up time T _wnamely, (step 501) then whether the stand-by period, if the stand-by period not yet then, then check whether the hop transmission (step 209) needing to carry out dividing into groups, if do not needed, then from mobile destination base station 11a forward come grouping it is preferentially sent to mobile radio station 14 (step 210).But, when forward occur postponing thus need to carry out the hop transmission divided into groups time, scheduling unit 22 performs the hop transmission of 22 groupings received of standing from higher level.In order to perform hop transmission, the classification number of type field of packet header of hop transmission will be set as 010 (type=010), make mobile radio station 14 can identify this grouping be jump grouping, then by this transmitted in packets to mobile radio station (step 210).

With process concurrently above, switch control portion 24b to moving source base station 11a send resource release message (step 212), return step 501, check the stand-by period whether then, if not yet then, then repeated execution of steps 209 and process afterwards.

On the other hand, if the grouping of transmission No. type then, is then set to " 011 " at once by the stand-by period after the stand-by period then in step 501.Namely, after then, at once last packet identification code L is added to the grouping that will transmit, and this grouping (last grouping) is transferred to mobile radio station (step 502 ~ 503), then carry out reprocessing, terminate switching controls (212 ~ 213).

In addition, in step 502, in order to can identify the last grouping that addition of last packet identification code L be from moving source base station 11a forward come grouping, or to stand 12 groupings received from higher level, when for No. type being set as " 011 " the former, when for No. type being set as " 100 " when the latter.The process of reordering of mobile radio station 14 described later is so just made to become easy.

The action of mobile radio station

Figure 16 is the action flow chart of mobile radio station, marks identical label to the step identical with the motion flow in Fig. 8.The determination part 34a of mobile radio station notifies accepting state etc. by measuring report to moving source base station 11a.Afterwards, control part 34 waits for the HO Indication message sent from moving source base station, when receiving HO Indication message, guarantee to keep synchronous with mobile destination base station 11b by L1/L2 signaling, after ensure that synchronously, send the report (step 271 ~ 274) switched to mobile destination base station.

Then, control part 34 checks that whether received grouping is for jumping over grouping, in other words, check whether the grouping (step 600) for type=010, if jump grouping, then this grouping is got rid of and to be kept in buffer 32 (step 601) outside the object that reorders.

On the other hand, if not jump grouping, then whether the grouping received by checking is last grouping, in other words, checks whether the grouping (step 602) into type=011.If not last grouping, then start to reorder, and in order PDCP PDU grouping is rearranged, generate PDCP SDU and pass to upper layer (step 603).

Then, scheduled time T is checked _mwhether then (step 604), if setting-up time T _mnot yet then, then step 600 and process is afterwards repeated, and if setting-up time T _mthen, then terminate process of reordering, then from the PDCP PDU not yet passing to upper layer divides into groups, delete header and generate PDCP SDU, and being passed to upper layer (step 605).Then, the grouping outside the object that reorders is passed to upper layer and end process (step 606).

On the other hand, in step 602, if received grouping is last grouping, then stop reordering process (step 607) at once.Now, if last grouping forwards the grouping of coming, then generate PDCP SDU by this last grouping and divide into groups and pass to upper layer, stop reordering.In addition, if last grouping to be stood 12 groupings received from higher level, then stop at once reordering, this last grouping is connected on the last of the grouping outside the object that reorders.Then, the grouping outside the object that reorders is passed to upper layer and end process (step 606).

As mentioned above, according to the 2nd embodiment, mobile radio station detects with reference to last packet identification code the situation forwarding and terminate, and can stop immediately reordering thus.Therefore, it is possible to eliminate the time of delay of data, improve the throughput of entire system.

(D) the 3rd embodiment

So far shown order information (sequence number n, m) be the simple numbering utilized for convenience of explanation, and in fact order information is added by base station.

As previously shown, in LTE communication system, forwarding implements according to the data unit of PDCP SDU.Therefore, when occurring to forward, Sequence Number field cannot be sent from moving source base station 11a to mobile destination base station 11b, thus needing to carry out notification sequence number (Sequence Number) someway.

In the present embodiment, sequence number is informed to mobile destination base station by moving source base station 11a together with PDCP SDU data, and this sequence number is added to the next PDCP SDU data (grouping) of forwarding based on this sequence number by mobile destination base station.

The sequence number of PDCP PDU to be attached in corresponding PDCP SDU data (grouping) (in band) by Figure 17, and passes through the example that datum plane (U-Plane) carries out notifying.Although illustrate only PDCPSDU data in fig. 17 and accompany the sequence number SN of these data, in order to using these PDCP SDU data as a component group, also need additional control information (header information).Moving source base station 11a is when each forwarding PDCP SDU data, capital notifies the sequence number SN attached in these PDCP SDU data according to the form of Figure 17, this sequence number is added to the next PDCP SDU data (grouping) of forwarding based on this sequence number by mobile destination base station 11b.

That is, under the situation of Figure 17, first moving source base station 11a forwards sequence number n-5 and initial PDCP SDU data by datum plane U-plane.Then, sequence number n-3 and next PDCP SDU data are forwarded by U-plane.Afterwards, forward from higher level stand 12 receive PDCP SDU data n-1, n time, similarly forward sequence number PDCP SDU data and sequence number thereof by U-plane to mobile destination base station 11b.In the 11b of mobile destination base station, owing to receiving sequence number n-5, n-3, n-1, n of being notified by U-plane, can identify thus forward the sequence number of data come.

The sequence number SN of PDCP PDU to be attached in corresponding PDCP SDU data (in band) and is notified by U-Plane by Figure 18, while moving source base station 11a the sequence number of failing to confirm the PDCP SDU data normally received by mobile radio station is carried out as next SN the example that notifies by control plane (C-plane).In the transfer sequence figure of Figure 19, the sequence number undertaken by this C-plane (next SN) notice is expressed as " SN handing-over ".SN handing-over can carry out HO with moving source base station 11a to mobile destination base station 11b asks side by side to carry out.

In the situation of Figure 18, first moving source base station 11a forwards sequence number n-5 and initial PDCP SDU data by U-plane.Then, sequence number n-3 and next PDCP SDU data are forwarded by U-plane.In addition, the sequence number n-5 failing to confirm the PDCP SDU normally received by mobile radio station is only informed to mobile destination base station 11b (SN handing-over) as next SN by C-plane by moving source base station 11a simultaneously.Afterwards, moving source base station 11a forward from higher level stand 12 receive PDCP SDU data n-1, n time, similarly forward PDCP SDU data and sequence number thereof via U-plane to mobile destination 11b.Mobile destination base station 11b receives the sequence number n-5 notified by C-plane and sequence number n-5, n-3, n-1, n of being notified by U-plane, but because the sequence number notified by U-plane is larger than the sequence number notified by C-plane, therefore based on this sequence number notified by U-plane to PDCP SDU data appended sequence number after this, and be transferred to mobile radio station.That is, mobile destination base station 11b ignores the sequence number n-5 notified by C-plane.

Figure 20 is the example of the situation that there are not the PDCP SDU data that will forward completely.

As next SN, moving source base station 11a fails to confirm the sequence number n+1 normally received by mobile radio station to mobile destination base station 11b notice via C-plane.If the stand-by period then when moving source base station 11a does not receive PDCP SDU data, then mobile destination base station 11b is based on the sequence number notified by C-plane to PDCP SDU data appended sequence number after this, and is transferred to mobile radio station.That is, the sequence number of the 12 grouping m received that stand from higher level is set to n+1 and is transferred to mobile radio station by mobile destination base station 11b.

Above, according to the present invention, the grouping come promptly can be transferred to mobile radio station as jump grouping, the time of delay of data can be eliminated, improve the throughput of entire system from higher level station to mobile destination base-station transmission.In addition, mobile radio station gets rid of grouping of jumping from the object of control (sequential control) of reordering, and carries out sequential control, according to sequence number order, grouping is passed to epigyny device to the grouping outside grouping of jumping.Its result, even if mobile radio station only has a sequential control function, the sequential control of the Object group that also can correctly carry out reordering.

In addition, according to the present invention, mobile radio station detects with reference to last packet identification code the situation forwarding and terminate, and can stop immediately reordering thus.Therefore, it is possible to eliminate the time of delay of data, improve the throughput of entire system.

Claims (3)

1. a wireless communication system, is characterized in that,

This wireless communication system has: moving source base station, mobile destination base station and mobile radio station,

Described mobile radio station has:

Receiving element, it receives PDCP PDU and a First ray number from described moving source base station, the 2nd PDCP PDU is received from described mobile destination base station, wherein, the 2nd PDCP PDU the second sequence number of utilizing described moving source base station to forward to described mobile destination base station and PDCP SDU generate;

Memory cell, it stores the PDCP SDU corresponding with a described PDCP PDU and the PDCP SDU corresponding with described 2nd PDCPPDU; And

Reorder unit, and it, according to this First ray number and the second sequence number, sequentially sends the PDCPSDU stored by number.

2. wireless communication system according to claim 1, is characterized in that,

Described second sequence number is forwarded to described mobile destination base station by control plane from described moving source base station.

3. wireless communication system according to claim 1, is characterized in that,

Described PDCP SDU and described second sequence number are forwarded to described mobile destination base station by user plane from described moving source base station.