CN101969677B - Mobile control device, handover control method and mobile communication system - Google Patents

Abstract

The invention provides a mobile control device and a handover control method in a mobile communication system and the mobile communication system. The mobile communication system executes handover control over the switching of communication base stations of the mobile terminal along the movement of the mobile terminal. In the handover control method, the mobile control device selects candidates for more than 1 handover base station according to communication state, determines the transmission speed of multicast communication data according to the communication capability of each handover base station candidates and transmits communication data to each handover base station candidate at the transmission speed, and the handover base station candidate which is determined as the handover base station sends the multicast and the stored communication data to a mobile terminal.

Description

Mobile controller and hand over control method and mobile communication system

The application is to be on December 27th, 2005 applying date, and application number is 200580051579.3, and denomination of invention is the divisional application of the application for a patent for invention of " mobile controller and hand over control method ".

Technical field

The present invention relates to mobile controller and hand over control method and mobile communication system, particularly follow the movement of mobile terminal to switch mobile controller and hand over control method and the mobile communication system Handoff Control, in mobile communication system of the base station of this communication of mobile terminal.

Background technology

Figure 30 is the structure chart that uses the mobile communication system of IP (Internet Protocol, Internet Protocol), and mobile controller MCA has wireless base station BTS 1～BTS n and multiple mobile terminal MS (only illustrating 1).Mobile controller MCA is connected with the IP network of the cable network as upper strata, and, with multiple base station BTS 1～BTS n wired connections, they are controlled.Mobile terminal MS in base station BTS 1～BTS n and community CL 1～CL n carries out radio communication.

Never the grouping that illustrated terminal mails to mobile terminal MS, via IP network, sends to the mobile controller MCA that accommodates this mobile terminal.At mobile terminal MS, in the time that community CL 1 is interior, mobile controller MCA sends grouping to the base station BTS 1 of accommodating this community, and base station BTS 1 is to this grouping of mobile terminal MS wireless transmission.After, keeping community CL 1 when interior at mobile terminal MS, mobile controller MCA is controlled to mobile terminal MS and object terminal communicates by above-mentioned path.In the time that mobile terminal MS moves and moves to abutting subdistrict CL 2, mobile controller MCA is switched to base station BTS 2 by the base station of relaying from base station BTS 1 by Handoff Control.

In the mobile communication of above-mentioned use IP, consider that application can realize the Mobile IP (Mobile IP, RFC 2002, RFC 3775) that the mobility (mobility) in IP layer is controlled.By apply this technology in mobile network, even if such mobile terminal MS changes the base station (handover) that connects destination in communication as shown in figure 30, also can continue IP-based communication.In honeycomb type mobile communication of future generation, also study and import Mobile IP as mobility control protocol.In honeycomb type mobile communication of future generation, compared with the 3G system of the main flow as current, require more jumbo high-speed communication, so in order to realize high-speed packet transmission, make the structure of Mobile IP high speed motion essential.

The key character of Mobile IP is, although provided the framework relevant to the signaling transmitting for dividing into groups, the concrete standard relevant to grouping transfer control provides not yet.Therefore,, in the time that hope makes Mobile IP high speed motion, need (1) to reduce the technology of the delay that causes of signaling, (2) for transmitting at a high speed the load mode of grouping.

As the method relevant to above-mentioned (1) for making Mobile IP high speed motion, Hierarchical Mobile IPv6 Mobility Management (HMIPv6, multilevel hierarchical mobile IPv6 mobile management) (non-patent literature 1) has been proposed.In addition, as the method relevant to above-mentioned (2), Fast Handovers for Mobile IPv6 (FHO, the Fast Handoff of mobile IP v 6) (non-patent literature 2), method (patent documentation 1) to multicast (multicast) grouping in advance of multiple mobile candidate's destination base station of mobile terminal have been proposed.In addition, also propose HMIPv6 expansion to have the Hierarchical Mobile IPv6with Buffering (HMIPv6-B, the multilevel hierarchical mobile IPv6 of band buffering) (non-patent literature 3) of grouping transmission control method.But, the problem points below existing in these modes.

The problem points of HMIPv6: HMIP cuts down the mode that the signaling in Mobile IP is object.Although HMIP has realized by cutting down signaling the high speed that grouping transmits, and does not make any contribution for the high speed of tranmission techniques itself.

The problem points of FHO: FHO is the method for speeding up of grouping tranmission techniques.Particularly, be the method that from moving source base station, mobile destination base station is transmitted in advance residual grouping in the time of the handover of mobile terminal.But, in the method, due to using known mobile destination base station as prerequisite, so in the time cannot determining the base station of mobile destination, the existence problem transmitting of cannot dividing into groups.

The problem points of HMIPv6-B: HMIPv6-B is the method to the high speed of the pooling feature of the various function addition groupings of HMIPv6 the transmission of consideration grouping simultaneously.Pooling feature is to be undertaken by the multiple handovers of management base station candidate's mobile controller.By the method, can realize the handover that reduces signaling delay and packet loss.But, exist because the buffering of grouping causes the problem points increasing time of delay.

The problem points of multicast: multicast is as shown in figure 31 like that to multiple handovers base station candidate BTS 2～BTS 4 method of multicastapackets in advance of mobile terminal MS in the time of handover.

Figure 32 is mobile controller MCA for multicast is described and the structure example of base station apparatus BTS 1～BTS n.Mobile controller MCA has: the 101a of wired network interface portion (later by interface referred to as I/F), and it carries out the interface control between IP network; The 101b of base station I/F portion, it carries out the interface control between base station; Send data processing division 101c, it carries out the Control on Communication of user grouping and control packet; And handover/multicast control part 101d, it carries out handover and multicast control.Each base station BTS 1～BTS n has identical structure, has: the mobile controller I/F 102a of portion, and it carries out the interface control between mobile controller MCA; The 102b of radio communication I/F portion, it carries out the interface control between mobile terminal MS; Send data processing division 102c, it carries out the Control on Communication of user grouping and control packet; With the 102d of Handoff Control portion, it carries out Handoff Control.Between mobile controller MCA and each base station BTS 1～BTS n, connect by 1 cable respectively, can pass through control channel, data channel and freely send and receive control packet, user grouping between them.

Figure 33 is the detailed structure view of mobile controller MCA, focuses on down direction communication and illustrates.In transmission data processing division 101c, buffer part 112 and the multicast portion 113 of sending copied and is input to the grouping of input by packet copies portion 111.Send buffer part 112 interim savings input grouping and suitably send to the 101b of base station I/F portion, multicast portion 113, when by handover/multicast control part 101d instruction multicast, copies and via sending buffer part 114a～114c and the 101b of base station I/F portion to handover base station candidate BTS 2～BTS 4 multicasts the grouping of input.In handover/multicast control part 101d, Handoff Control portion 121 controls the entirety of handover, multicast control when multicast control part 122 is carried out handover.

Figure 34 be adopt Handoff Control sequential when multicast want portion's key diagram, Figure 35 is the handling process of handover/multicast control part 101d.

In the time that mobile terminal MS and base station BTS 1 communicate, the Handoff Control portion 121 of mobile controller MCA asks mobile terminal MS to measure and report wireless status termly.Mobile terminal MS, in the time receiving wireless status mensuration report request, is measured the incoming level from peripheral base station BTS2～BTS n, reports to mobile controller MCA via the base station BTS 1 in communication.Handoff Control portion 121 is in the time receiving this report, determine whether and need handover (step 151～152) with reference to the signal level of reporting, in the time of needs handover, the multiple base stations corresponding with the signal level that exceedes threshold value are defined as to handover base station candidate (step 153), notify this handover base station candidate to multicast control part 122.In Figure 34, base station BTS 2, BTS 3, BTS 4 are handover base station candidate.

After handover base station candidate determines, multicast control part 122 checks the interface IP address, for example MAC Address (the Media Access Control Address that whether distinguish corresponding each base station, Media Access Control Address), in the time that MAC Address is not clear, explore by sending MAC Address the interface IP address that divides into groups to obtain corresponding base station.After these steps finish, multicast control part 122 carries out multicast instruction to multicast portion 113.

Thus, multicast portion 113 copies and to handover base station candidate BTS 2, BTS 3, BTS 4 multicasts (step 154) grouping.

With above-mentioned multicast concurrently, Handoff Control portion 121 determines handover base station (step 155).For example, be set point when above at the received electric field strength from base station BTS 2, this base station BTS 2 is defined as to handover base station.Next, Handoff Control portion 121 these base station BTS 2 setting wireless channels (step 156) of request.Then, control as follows: set (step 157) while replying receiving wireless channel from base station BTS 2, instruction sends the grouping to these base station BTS 2 multicasts to mobile terminal MS, and, send the grouping receiving from IP network to mobile terminal MS via base station BTS 2.In addition, multicast control part 122 stops multicast, and instruction abandons to the grouping of handover base station candidate's multicast that is not selected as handover base station, and carries out handover end process (step 158).

Figure 36 be Handoff Control another sequential want portion's key diagram.In this example, also suppose that mobile terminal MS is current to communicate with base station BTS 1, be provided with base station BTS 2～BTS n at the periphery of base station BTS 1.The sequential of mobile controller MCA and Figure 34 is similarly determined handover base station candidate with reference to the received signal level of the peripheral base station from mobile terminal MS report.But, in the sequential example of Figure 34, the report of signal level is carried out via base station BTS 1, but is undertaken by each base station in the present example.In this case, MAC Address, in the time that mobile controller MCA is carried out to the report of signal level, is notified in each base station.Therefore, different from the sequential of Figure 34, mobile controller MCA can carry out multicast after handover base station candidate and without the interface IP address of inquiry base station immediately determining.

By utilizing above method of multicasting, mobile terminal MS can receive data from handover base station BTS 2 immediately after handover, therefore, can realize handover at a high speed.This technology is applicable to the mobile network who uses Mobile IP, so be the strong high-speed packet transfer approach that can improve the problem of HMIPv6, FHO and HMIPv6-B.

But in method of multicasting in the past, the transfer rate of multicast is the transfer rate of the base station that connected before handover according to mobile terminal MS and solely determining.Therefore, in the time that multiple handovers base station candidate's communication capacity there are differences, for example, in the time that buffer size or wireless access way are different, the grouping that certain base station cannot collecting post's multicast and produce abandoning of grouping.Therefore, produce time of delay owing to abandoning resending of grouping, generation cannot synthetically realize the possibility of high speed handover.Illustrate that with Figure 31 the grouping in multicast in the past abandons.In Figure 31, the example from the residing base station BTS 1 of mobile terminal MS to ensuing handover base station candidate BTS 2～BTS 3 multicasts is shown.Consider that base station BTS 1～BTS 3 is the base stations that are applicable to IEEE802.11a (maximum 54Mb/s), base station BTS 4 is the situations that are applicable to the base station of 3G (maximum 384Kb/s).In multicast control in the past, the transfer rate of multicast is solely to determine according to the transfer rate of base station BTS 1 before this, and its maximum transfer rate is 54Mb/s.

The buffer capacity of each base station is configured to the size corresponding with the transfer rate of wireless access way, so the buffer capacity of handover base station candidate BTS 4 is designed to be less than the buffer capacity of handover base station candidate BTS 1～BTS 3.Therefore, the transfer rate 54Mb/s of the grouping coming to handover base station candidate BTS 4 multicasts is significantly greater than the maximum transfer rate 384Kb/s that NodeB can be accommodated, so all groupings that multicast comes cannot be housed in the buffer of base station BTS 4, are dropped because buffer overflows.Therefore, in the time that mobile terminal MS is handed over to base station BTS 4, resend abandoned grouping, cannot realize high speed handover owing to following the time of delay resending.

This problem not only produces in the handover between different system as above-mentioned example, in the handover in same system, also produces.For example, in moving source base station and mobile destination base station, in the case of the signal level of mobile terminal is extremely different, produce this problem.

In sum, in the handover of mobile terminal, in the time that mobile controller is not considered multiple handovers base station candidate's performance and is carried out multicast with single transfer rate, produce grouping because buffer overflows the multiple handovers base station candidate who is arranged in subordinate and abandon, produce problem points as following.

First, produce grouping while abandoning overflowing due to buffer, must resend the grouping being abandoned with end-to-end level, produce the problem that the propagation delay of grouping increases.Therefore, cannot realize high speed handover.

In addition, in base station BTS 4, due to the grouping that multicast comes, the available resource of other mobile terminals will reduce, thus produce the performance deterioration of these terminals problem, cannot accommodate the problem that newly starts the mobile terminal of communicating by letter.

Summary of the invention

While the object of the present invention is to provide one to carry out multicast under Handoff Control, in the candidate of handover base station, can not produce mobile controller and the hand over control method that grouping abandons because buffer overflows.

Another object of the present invention is to provide a kind of communication capacity of considering each base station (buffer capacity, Radio Resource utilize situation and communication quality QoS (Quality of Service)), and the transfer rate of the multicastapackets that base station is sent is set for and do not produced mobile controller and the hand over control method that grouping abandons.

Non-patent literature 1:Network Working Group Request for Comments 4140 (RFC 4140) " Hierarchical Mobile IPv6 Mobility Management (HMIPv6) "

Non-patent literature 2:Network Working Group Request for Comments 4068 (RFC 4068) " Fast Handovers for Mobile IPv6 "

Non-patent literature 3:VTC-2003 Spring " Transmission Quality Evaluation forHierarchical Mobile IPv6 with Buffering Using Test Bed "

Patent documentation 1: TOHKEMY 2004-282249 communique

The present invention relates to follow the movement of mobile terminal to switch mobile controller and the hand over control method Handoff Control, in mobile communication system of the base station of this communication of mobile terminal.

Hand over control method of the present invention

Hand over control method of the present invention has: the 1st step, according to the candidate of selected 1 the above handover base station of communications status; The 2nd step, determines the transfer rate of cast communication data according to each handover base station candidate's communication capacity; The 3rd step, transmits communication data with this transfer rate to each handover base station candidate; And the 4th step, be confirmed as the communication data that the handover base station candidate of handover base station sends described multicast and preserves to mobile terminal.

In described the 2nd step, described communication capacity is the buffer capacity of the buffer that has of each handover base station candidate, determine the transfer rate of cast communication data for each described handover base station candidate according to this buffer capacity, or, the minimum transfer rate in described handover base station candidate is made as to public multicast transfer rate.

In described the 2nd step, described communication capacity is the idle condition of the Radio Resource in each handover base station candidate, determines the transfer rate of cast communication data according to the idle condition of this Radio Resource for each described handover base station candidate.

In described the 2nd step, described communication capacity is the enforceable QoS (service quality) in each handover base station candidate, determines the transfer rate of cast communication data according to this enforceable QoS for each described handover base station candidate.

In described the 3rd step, in multicast way, the variation of the communication capacity in described handover base station candidate is detected, change adaptively the transfer rate for described handover base station candidate's multicast according to this communication capacity after changing, or from the sending destination of multicast, remove described handover base station candidate and stop multicast.

Mobile controller of the present invention

Mobile controller of the present invention has: handover base station candidate's determination portion, and it is according to the candidate of selected 1 the above handover base station of communications status; Transfer rate determination portion, its communication capacity according to each handover base station candidate is determined the transfer rate of cast communication data; Multicast portion, it transmits communication data with this transfer rate to each handover base station candidate; And handover base station determination portion, one of described multiple handovers base station candidate is defined as handover base station by it.

The data that described each handover base station candidate preserves institute's multicast, and the handover base station candidate who is confirmed as handover base station sends the communication data of this preservation to mobile terminal.

The buffer capacity of the buffer that described transfer rate determination portion has each handover base station candidate is considered as described communication capacity, determine the transfer rate of cast communication data for each described handover base station candidate according to this buffer capacity, or, the minimum transfer rate in described handover base station candidate is defined as to public multicast transfer rate.

The idle condition of the Radio Resource in each handover base station candidate is considered as described communication capacity by described transfer rate determination portion, determines the transfer rate of cast communication data according to the idle condition of this Radio Resource for each described handover base station candidate.

The enforceable QoS (service quality) in each handover base station candidate is considered as described communication capacity by described transfer rate determination portion, determines the transfer rate of cast communication data according to this QoS for each described handover base station candidate.

Described multicast portion has transfer rate adjustment part, this transfer rate adjustment part with described definite transfer rate to described each handover base station candidate's multicast communication data, this transfer rate adjustment part has buffer, and this buffer is for each preservation of each handover base station candidate data corresponding with the difference of the communication data speed of inputting from network and described multicast speed.

When described transfer rate determination portion detects the variation of the communication capacity in described handover base station candidate in multicast way, change adaptively the transfer rate for described handover base station candidate's multicast according to this communication capacity after changing, or from the sending destination of multicast, remove described handover base station candidate and stop multicast.

Brief description of the drawings

Fig. 1 is for communication system architecture example of the present invention is described.

Fig. 2 is the structure chart of mobile controller.

Fig. 3 is the structure chart of base station apparatus.

Fig. 4 is Handoff Control sequential of the present invention.

Fig. 5 is that transfer rate is determined handling process.

Fig. 6 is the handling process of calculating the transfer rate of multicast for each handover base station candidate.

Fig. 7 is the example of message format.

Fig. 8 is the example that shows the message of table 1 with the form of Fig. 7.

Fig. 9 is the example that shows the message of table 2 with the form of Fig. 7.

Figure 10 is the handling process of the Handoff Control of handover/multicast control part of mobile controller.

Figure 11 is that handover stops controlling processing.

Figure 12 is another Handoff Control sequential key diagram of the present invention.

Figure 13 is the effect key diagram of the 1st embodiment.

Figure 14 is the effect key diagram of the 1st embodiment.

Figure 15 is the effect key diagram of the 1st embodiment.

Figure 16 is the effect key diagram of the 1st embodiment.

Figure 17 is the overall diagram of the 2nd embodiment.

Figure 18 is the structure chart with the base station of handover/multicast control function.

Figure 19 is the Handoff Control sequential of the 2nd embodiment.

Figure 20 is the diagrammatic illustration figure of the 3rd embodiment.

Figure 21 is the state diagram in handover way.

Figure 22 becomes inadequate resource and stops to the state of handover base station candidate's multicast control.

Figure 23 be the 3rd embodiment Handoff Control sequential want portion's key diagram.

Figure 24 is the diagrammatic illustration figure of the 2nd mode of the 3rd embodiment.

Figure 25 be Handoff Control sequential want portion's key diagram.

Figure 26 is the diagrammatic illustration figure of the 3rd mode of the 3rd embodiment.

Figure 27 is multicast key diagram in the past.

Figure 28 is the multicast key diagram of the 4th embodiment.

Figure 29 is the multicast key diagram of the 2nd mode of the 4th embodiment.

Figure 30 is the structure chart that uses the mobile communication system of IP (Internet Protocol).

Multicast key diagram when Figure 31 is handover.

Figure 32 is the structure example of mobile controller and base station apparatus.

Figure 33 is the detailed structure view of mobile controller.

Figure 34 be adopt Handoff Control sequential when multicast want portion's key diagram.

Figure 35 is the handling process of handover/multicast control part.

Figure 36 be Handoff Control another sequential want portion's key diagram.

Embodiment

(A) the 1st embodiment

(a) communication system architecture

Fig. 1 is for communication system architecture example of the present invention is described, mobile controller MCA, wireless base station BTS 1～BTS 5 and multiple mobile terminal MS (only illustrating 1) are shown.Mobile controller MCA is connected with the IP network on upper strata, and with multiple base station BTS 1～BTS n wired connections, they is controlled, and the mobile terminal MS in base station BTS 1～BTS n and community CL 1～CL n carries out radio communication.

Mobile terminal MS, in base station BTS 1, is selected BTS 2～BTS 4 as the handover base station candidate of this mobile terminal, the multicast transmission that mobile controller MCA divides into groups to these base stations by mobile.In Fig. 1, base station BTS 1 is the base station that is applicable to IEEE 802.11a (54Mb/s), base station BTS 2, BTS 3 are applicable to HSDPA (the High Speed Downlink Packet Access of 3GPP, high-speed downlink packet access) base station (maximum transfer rate 14.4Mb/s), base station BTS 4 is the base stations (maximum transfer rate 384Kb/s) that are applicable to 3GPP.

(b) mobile controller

As shown in Figure 2, mobile controller MCA has: wired I/F 1a of portion, it carries out and cable network (IP network) between interface control; The 1b of base station I/F portion, it carries out the interface control between base station; Send data processing division 1c, it carries out the Control on Communication of user grouping and control packet; And handover/multicast control part 1d, it carries out handover and multicast control.

In transmission data processing division 1c, packet copies portion 11 copies and is input to transfer rate to the grouping of input and adjusts buffer part 12 and multicast portion 13.Multicast portion 13, when by handover/multicast control part 1d instruction multicast, copies and stores into transfer rate to the grouping of input and adjust in buffer part 14a～14c.Transfer rate is adjusted buffer part 12,14a～14c for adjusting the poor of the input speed of grouping and output speed.Owing to there being the different possibility of transfer rate of multicast for each handover base station candidate, adjust buffer part 14a～14c so preferably transfer rate is set for each handover base station candidate in mobile controller MCA.

The grouping being stored in transfer rate adjustment buffer part 12,14a～14c, according to the multicast transfer rate of indicating from handover/multicast control part 1d in the time of handover, is read in transfer rate adjustment part 15, is input to and sends buffer part 16,17a～17c.Send buffer part 16 and send input grouping via the 1b of base station I/F portion to base station BTS 1 in communication, and, send buffer part 17a～17c put aside temporarily input grouping and suitably via the 1b of base station I/F portion to handover base station candidate BTS 2～BTS4 multicast.

Conventionally, adjust buffer part 12 → transfer rate adjustment part 15 → transmission buffer part 16 → base station 1b of I/F portion from the grouping of IP network via 1a → packet copies portion of cable network I/F portion 11 → transfer rate, do not carry out transfer rate adjustment and send to the base station BTS 1 communicating with mobile terminal MS.On the other hand, carry out multicast under Handoff Control time, grouping from IP network is copied by multicast portion 13, adjust buffer part 14a～14C → transfer rate adjustment part 15 → transmission buffer part 17a～17c → base station 1b of I/F portion via transfer rate, to each handover base station candidate BTS2～BTS 3 multicasts.

In handover/multicast control part 1d, Handoff Control portion 21 controls the entirety of handover, and multicast control part 22 has multicast control instruction unit 22a and controls data sending part 22b.Multicast control instruction unit 22a notifies handover base station candidate BTS 2～BTS 4 to carry out multicast to multicast portion 13, and, determine multicast transfer rate according to the communication capacity of handover base station candidate BTS 2～BTS 4, to transfer rate adjustment part 15 these transfer rates of input.Control data sending parts 22b obtained and kept each base station by the control packet data such as communication capacity from each handover base station candidate BTS 2～BTS 4.

(c) base station

Fig. 3 is the structure chart of base station BTS 1～BTS n, and each base station has identical structure.Base station has: the mobile controller I/F 2a of portion, and it carries out the interface control between mobile controller MCA; The 2b of radio communication I/F portion, it carries out the interface control between mobile terminal MS; Send data processing division 2c, it carries out the Control on Communication of user grouping and control packet; The 2d of Handoff Control portion, it carries out Handoff Control; Control information sending part 2e, it sends control packet to mobile controller MCA; With the 2f of communications status management department.The 2f of communications status management department is the part that the state of communication capacity to representing base station manages, have cache management portion 31, the managing radio resources of management buffer capacity state (behaviours in service of channel, frequency band etc.) RRM portion 32 and manage the communication quality management department 33 of executable communication quality (QoS).Between mobile controller MCA and each base station BTS 1～BTS n, connect by 1 cable respectively, can pass through control channel, data channel and freely send and receive control packet, user grouping between them.

(d) Handoff Control sequential

Fig. 4 is Handoff Control sequential of the present invention.

In the time that mobile terminal MS and base station BTS 1 communicate (with reference to Fig. 1), the Handoff Control portion 21 of mobile controller MCA asks mobile terminal MS to measure and report wireless status termly.Mobile terminal MS, in the time receiving wireless status mensuration report request, is measured the incoming level from peripheral base station BTS 2～BTS n, reports to mobile controller MCA via the base station BTS 1 in communication.

Handoff Control portion 21 is in the time receiving this report, determine whether and need handover with reference to the signal level of reporting, in the time of needs handover, 1 corresponding with the signal level that exceedes threshold value above base station is defined as to handover base station candidate, notifies this handover base station candidate to multicast control part 22.In Fig. 4, base station BTS 2, BTS 3, BTS 4 are handover base station candidate.

After handover base station candidate determines, the multicast control instruction unit 22a of multicast control part 22 checks the MAC Address of whether having distinguished corresponding each base station, in the time that MAC Address is not clear, obtains the interface IP address of corresponding base station by sending MAC Address exploration grouping.After these steps finish, multicast control instruction unit 22a paired domination number is controlled according to sending part 22b, carries out sending by message the control of the information that obtains the communication capacity that represents each handover base station candidate BTS 2～BTS 4.In addition, the information of obtained expression communication capacity is for determining multicast transfer rate.

The state that represents the communication capacity of base station comprises:

(1) buffer capacity that can guarantee;

(2) idle condition of Radio Resource;

(3) could guarantee QoS that mobile terminal is wished etc.

At this, control data sending part 22b and send to each handover base station candidate BTS 2～BTS 4 control packet of investigating above-mentioned each state.By the report from base station of the control packet with reference to for this communication capacity investigation use, multicast control instruction unit 22a holds the communication capacity of each handover base station candidate BTS 2～BTS 4, determines multicast transfer rate according to this communication capacity.

The communication capacity investigation message that control data sending part 22b sends and the communication capacity report message of base station report can show respectively as shown in table 1, table 2.In addition, table 1 illustrates the example that could not guarantee QoS to base station investigation.

(table 1)

The control message (investigation request is not carried out in × expression) that mobile controller sends

	BTS 2	BTS 3	BTS 4	BTS 5
					(1) buffer capacity	○	○	○	×
(2) resource idle condition	○	○	○	×
					(3) could guarantee QoS	×	×	×	×

(table 2)

The communication capacity report message that base station sends

	BTS 2	BTS 3	BTS 4	BTS 5
					(1) buffer capacity	7Mb	7Mb	192Kb	×
(2) resource idle condition	1	1	1	×
					(3) could guarantee QoS	×	×	×	×

Could not guarantee that to base station investigation the reason of QoS is, suppose TCP (Transmission Control Protocol, transmission control protocol) as data transfer protocol end to end.In addition, because base station BTS 5 is not handover base station candidate, so do not send investigation control packet.In addition, in table 2, (1) represents the buffer capacity that can actually guarantee.Be that 500ms and each base station are can guarantee the buffer capacity suitable with maximum transfer rate time at hypothesis handoff time, in BTS2～BTS 4, can guarantee buffer capacity 7 (=14.4 × 0.5) Mb shown in table 2,7Mb, 192 (=384 × 0.5) kb.In the row (2) of table 2, in the situation that the value of being illustrated in is 0, cannot guarantee Radio Resource, in the situation that being 1, value can guarantee Radio Resource.In addition, in the row (3) of table 2, similarly, in the situation that the value of being illustrated in is 0, cannot provide the QoS of mobile terminal request, the QoS of mobile terminal request can be provided for 1 in the situation that in value.

As mentioned above, multicast control instruction unit 22a, in the time obtaining the information of communication capacity that represents each handover base station candidate BTS2～BTS 4, determines multicast transfer rate by this information.

Fig. 5 is that transfer rate is determined handling process.I is initialized as 0 (step 201) by multicast control instruction unit 22a, then, make i stepping and send the control message (step 202～204) of communication capacity investigation use to each handover base station candidate BTS i, receive the report message (step 205) of report communication capacity from each handover base station candidate BTS i.By the control of this step 202～204, multicast control instruction unit 22a, in the time receiving buffer capacity Bi (b) for i handover base station candidate BTS i, passes through following formula

Fi(b/s)＝Bi/HO#TIME

Transfer rate (transfer rate can the be provided) Fi (b/s) (step 206) that calculating can provide mobile terminal BTS i.Wherein, HO#TIME is handoff time.Next, obtain all handovers base station candidate BTS i (i=1,2 ..., provided transfer rate Fi (b/s) m) (i=1,2 ..., m), wherein minimum provided transfer rate Mi is provided, the provided transfer rate Mi of this minimum is made as to the public multicast transfer rate for each handover base station candidate BTS i.

In Fig. 5, in step 207, obtain the public multicast transfer rate for each handover base station candidate BTS i, but also can calculate for each handover base station candidate BTS i the transfer rate of multicast.Fig. 6 is the handling process of calculating the transfer rate of multicast for each handover base station candidate BTS i, and Ri (b/s) is the maximum transfer rate sending in the candidate BTS i of handover base station.Step 201～206 are identical with the flow process of Fig. 5.

Obtain by step 206 all handovers base station candidate BTS i (i=1,2 ..., provided transfer rate Fi (b/s) in m) (i=1,2 ..., m) after, i is initialized as 0 (step 301) by multicast control instruction unit 22a, then, make i stepping (step 302).Afterwards, less transfer rate in the provided transfer rate Fi (b/s) of handover base station candidate BTS i and the maximum transfer rate Ri (b/s) sending of handover base station candidate BTS i is provided and is made as Mi (step 303), for all handovers base station candidate BTS i (i=1,2 ..., m) repeat above-mentioned processing (step 304), Mi is made as to the multicast transfer rate (step 305) for handover base station candidate BTS i.

After the transfer rate of multicast is determined, multicast control instruction unit 22a carries out multicast instruction to multicast portion 13, and, input multicast transfer rate to transfer rate adjustment part 15.Thus, multicast portion 13 copies and is input to transfer rate to grouping and adjusts buffer part 14a～14c.In addition, multicast portion 13 is in order to distinguish grouping and the common grouping of multicast, to multicastapackets attach identifier.

Transfer rate adjustment part 15 is according to the multicast transfer rate for each handover base station candidate BTS 2, BTS 3, BTS 4, adjust buffer part 14a～14c from transfer rate and read grouping, via sending buffer part 17a～17c, the 1b of base station I/F portion to each handover base station candidate BTS 2, BTS 3, BTS 4 multicasts.

With above-mentioned multicast concurrently, Handoff Control portion 21 determines handover base stations.For example, be set point when above at the received electric field strength from base station BTS 2, this base station BTS 2 is defined as to handover base station.Next, Handoff Control portion 21 carries out radio bearer setting request (RB Setup request) to this base station BTS 2.Then, set while replying (RB Setup replys) receiving radio bearer from base station BTS 2, send hand-off request (HO instruction) via base station BTS 1 to mobile terminal MS.Thus, mobile terminal MS is carried out the handover from base station BTS 1 to base station MTS 2, sends handover reply (HO replys) after execution handover to base station BTS 2.

Base station BTS 2 is replied the grouping that sends institute's multicast and keep to mobile terminal MS by handover, and, send data transmission requests to mobile controller MCA.Mobile controller MCA stops multicast by data transmission requests, and, send the grouping receiving from IP network later to mobile terminal MS via base station BTS 2.Thus, base station BTS 2 sends handover to mobile controller MCA and completes notice, and the multicast control instruction unit 22a instruction of mobile controller MCA abandons to the handover base station candidate BTS 3 that is not selected as handover base station, the grouping of BTS4 multicast.

By carry out to the control message shown in handover base station candidate BTS 3, BTS 4 transmission tables 3 institute's multicast grouping abandon instruction.

(table 3)

The control message (investigation request is not carried out in × expression) that mobile controller sends

	BTS 3	BTS 4
			(1) buffer capacity	×	×
(2) resource idle condition	×	×
			(3) could guarantee QoS	×	×
(4) carry out abandoning of grouping	1	1

Fig. 7 is the example of message format, is (a) the form example of the message from base station BTS i to mobile controller MCA, is (b) the form example of the message from mobile controller MCA to base station BTS i.

In message format, (1)～(4) are message sequence number, (1) buffer capacity for guaranteeing, (2) be the idle condition of Radio Resource, (3), for could guarantee the QoS that mobile terminal is wished, (4) are for carrying out abandoning of grouping.The buffer capacity of message sequence number (1) shows with 8, and message sequence number (2)～(4) show with 1.In addition, base station IDs shows with 8, from base station BTS 1 be made as successively 00000001,00000010,00000011 ...The ID of mobile controller MCA is 00001000.Identification shows with 1, with reference to this territory in the situation that, is " 1 ", is " 0 " in the situation that of not reference.In addition, unit shows with 3, and 100 is Gb/s, and 010 is Mb/s, and 001 is Kb/s.

Fig. 8 is the example that shows the message of table 1 with the form of Fig. 7, (a) be the communication capacity investigation message from mobile controller MCA to base station BTS 2, (b) being the communication capacity investigation message from mobile controller MCA to base station BTS 3, is (c) the communication capacity investigation message from mobile controller MCA to base station BTS 4.

Fig. 9 is the example that shows the message of table 2 with the form of Fig. 7, (a) be the communication capacity report message from base station BTS 2 to mobile controller MCA, (b) being the communication capacity report message from base station BTS 3 to mobile controller MCA, is (c) the communication capacity report message from base station BTS 4 to mobile controller MCA.

(e) handling process of Handoff Control

Figure 10 is the handling process of the Handoff Control of handover/multicast control part 1d of mobile controller MCA.

The signal level that Handoff Control portion 21 measures with reference to mobile terminal MS judges whether to need handover, in the time of needs handover, the base station corresponding with the signal level that exceedes threshold value is defined as to handover base station candidate (step 401).

After handover base station candidate determines, multicast control part 22 carries out obtaining by message transmission the control (step 402) of the information of the communication capacity that represents each handover base station candidate BTS 2～BTS 4.Afterwards, judge whether to need the speed adjustment (step 403) of multicast transfer rate, determine transfer rate (step 404) according to the flow process of Fig. 5 or Fig. 6 when needed, carry out multicast (step 405) with this transfer rate.

With above-mentioned multicast concurrently, Handoff Control portion 21 determines handover base stations, and, carry out radio bearer to this handover base station (being made as base station BTS 2) and set request (step 406).Then, set (step 407) while replying receiving radio bearer from base station BTS 2, multicast control part 22 stops multicast, and instruction sends the grouping (step 408) to base station BTS 2 multicasts to mobile terminal MS.Next, Handoff Control portion 21 carries out handover end process (step 409).After, mobile controller MCA is controlled to and sends the grouping receiving from IP network via base station BTS 2 to mobile terminal BS.

In the handover of step 409 stops controlling, Handoff Control portion 21 as shown in step 409a～409d of Figure 11, instruction abandon to be selected as handover base station candidate BTS i beyond the base station BTS k of handover base station (i=1,2 ..., k-1, k+1 ..., the m) grouping of multicast.Be instructed to abandon grouping handover base station candidate BTS i (i=1,2 ..., k-1, k+1 ..., m) abandon the grouping that is attached with multicastapackets identifier.

Figure 12 is another Handoff Control sequential key diagram of the present invention.In this sequential, send address in the sequential of Fig. 4 simultaneously and explore the control message (with reference to table 1) of message and communication capacity investigation use, receiver address notification message and communication capacity report message (with reference to table 2) simultaneously.Like this, receive 2 message by send simultaneously, can reduce message and send receive delay.

(f) effect of the 1st embodiment

Figure 13～Figure 16 is the effect key diagram of the 1st embodiment.Wherein, suppose that mobile terminal MS is from base station BTS 1 to base station BTS 4 handovers.

As shown in figure 13, suppose after base station BTS 1 transmission of moving source is accomplished to dataA and produce handover, and after supposition, the data B sending to mobile controller MCA from IP network is carried out to multicast transmission.

Now, in the time that mobile terminal MS averages TCP (Transmission Control Protocol, the transmission control protocol) communication of throughput 1Mb/s, during the 500ms as handoff time, transmit the data of 500Kb.Therefore, in the time of handover, abandon for fear of grouping, base station BTS 4 need at least be guaranteed the buffer capacity of 500Kb.Figure 14 illustrates in method of multicasting in the past the situation after handover just.In previous methods, because the 1Mb/s of the transfer rate of the TCP communication using as base station BTS 1 carries out multicast, so during the 500ms as handoff time, to the data of base station BTS 4 multicast 500Kb.But the buffer BF4 maximum of base station BTS 4 also only can be guaranteed the buffer capacity of 192Kb, so divide into groups to abandon because buffer overflows to produce.Because the controlling organization that resends end to end by TCP resends abandoned grouping, so produce time of delay owing to resending.

On the other hand, according to the 1st embodiment, the buffer capacity (=192Kb) of the buffer BF 4 of mobile controller MCA consideration base station BTS 4 is determined multicast transfer rate according to the handling process of Fig. 5.For example, as shown in figure 15, the transfer rate of multicast is solely defined as to 380Kb/s.Like this, after multicast transfer rate is determined, during the 500ms as handoff time, to the data of base station BTS 1 and base station BTS 4 multicast 190Kb, remaining data savings is adjusted in buffer part 12,14c in the transfer rate of mobile controller MCA.By this control, can avoid the grouping producing in previous methods to abandon, mobile terminal MS can start the TCP communication of grouping from handover just.Therefore, can avoid the communication of the time of delay that resends control of following TCP.

In addition, as shown in figure 16, mobile controller MCA is according to the handling process of Fig. 6, can be according to the communication capacity (buffer capacity) of each base station BTS 1, BTS 4 transfer rate during for each base station sets multicast.For example, carry out the transmission of data with 1Mb/s to base station BTS 1, transmit data to BTS4 with the transfer rate of 380Kb/s.Thus, during the 500ms as handoff time, transmit the data of 500Kb to base station BTS 1, transmit the data of 190Kb to base station BTS 4, divide into groups to abandon because buffer overflows to produce.Now, adjust the data of buffer part 14c savings 310Kb to the transfer rate that is arranged on the base station BTS 4 on mobile controller MCA.

(B) the 2nd embodiment

(a) summary

In the 1st embodiment, suppose that mobile controller MCA is positioned at the upper strata of base station.But, in the 2nd embodiment, make the base station having communicated before this there is handover/multicast control function.

Figure 17 is the overall diagram of the 2nd embodiment, the base station BTS 1 having communicated with mobile terminal MS before handover carries out Handoff Control and judges whether handover, the in the situation that of handover, determine handover base station candidate BTS 2～BTS 4, determine multicast transfer rate according to the communication capacity of each handover base station candidate BTS 2～BTS 4, with this multicast transfer rate to each handover base station candidate BTS 2～BTS 4 multicastapackets.In addition, base station BTS 1 is determined handover base station concurrently with multicast, and, make this handover base station (being made as base station BTS 2) setting wireless channel, then stop multicast, and instruction sends the grouping to base station BTS 2 multicasts to mobile terminal MS.Next, base station BTS 1 carries out handover end process, and instruction abandons to being selected as the handover base station candidate BTS 3 beyond the base station BTS 2 of handover base station, the grouping of BTS 4 multicasts.

(b) structure of base station

Figure 18 is the structure chart with the base station BTS 1 of above-mentioned handover/multicast control function, has the mobile controller shown in Fig. 2, Fig. 3 of the 1st embodiment and this two side's of base station structure.That is, in base station BTS 1, have: the mobile controller I/F 3a of portion, it carries out the interface control between mobile controller MCA; The 3b of wireless communication interface portion, it carries out the interface control between mobile terminal MS; Send data processing division 3c, it carries out the Control on Communication of user grouping and control packet and the multicast of grouping; The 3d of Handoff Control portion, it carries out Handoff Control as base station; The 3e of communications status management department, it represents the state of communication capacity as BTS management; And handover/multicast control part 3f, it carries out handover and the multicast control of entire system.

In transmission data processing division 3c, packet copies portion 41 copies and is input to transfer rate to the grouping of input and adjusts buffer part 42 and multicast portion 43.Multicast portion 43, when by handover/multicast control part 3f instruction multicast, copies and stores into transfer rate to the grouping of input and adjust in buffer part 44a～44c.Transfer rate is adjusted buffer part 42,44a～44c for adjusting the poor of the input speed of grouping and output speed.

The grouping being stored in transfer rate adjustment buffer part 42,44a～44c, according to the multicast transfer rate of indicating from handover/multicast control part 3f in the time of handover, is read in transfer rate adjustment part 45, is input to and sends buffer part 46,47a～47c.Send the interim savings input of buffer part 46 and divide into groups and suitably send to mobile terminal MS via the 3b of base station I/F portion, in addition, send buffer part 47a～47c and put aside input grouping also suitably to handover base station candidate BTS 2～BTS 4 multicasts temporarily.

The 3e of communications status management department is the part that the state of communication capacity to representing base station manages, have cache management portion 51, the managing radio resources of management buffer capacity state (behaviours in service of channel, frequency band etc.) RRM portion 52 and manage the communication quality management department 53 of executable communication quality (QoS).

In handover/multicast control part 3f, Handoff Control portion 61 controls the entirety of handover, and multicast control part 62 has multicast control instruction unit 62a and controls data sending part 62b.Multicast control instruction unit 62a notifies handover base station candidate BTS 2～BTS 4 to carry out multicast to multicast portion 43, and, determine multicast transfer rate according to the communication capacity of handover base station candidate BTS 2～BTS 4, to transfer rate adjustment part 45 these transfer rates of input.Control data sending parts 62b by obtain and keep the data such as communication capacity of each base station from the control packet of each handover base station candidate BTS 2～BTS 4.

(c) Handoff Control sequential

Figure 19 is the Handoff Control sequential of the 2nd embodiment, from the base station BTS 1 in communication of mobile terminal carry out the control of handover/multicast aspect different with the sequential of Fig. 4.

Ask termly mobile terminal MS to measure and report wireless status with the Handoff Control portion 61 of the base station BTS 1 in communication of mobile terminal.Mobile terminal MS, in the time receiving wireless status mensuration report request, is measured the incoming level from peripheral base station BTS 2～BTS n, reports to the base station BTS 1 in communication.

Handoff Control portion 61 is in the time receiving this report, determine whether and need handover with reference to the signal level of reporting, in the time of needs handover, the multiple base stations corresponding with the signal level that exceedes threshold value are defined as to handover base station candidate, notify this handover base station candidate to multicast control part 62.

After handover base station candidate determines, the multicast control instruction unit 62a of multicast control part 62 checks the MAC Address of whether having distinguished corresponding each base station, in the time that MAC Address is not clear, obtains the interface IP address of corresponding base station by sending MAC Address exploration grouping.After these steps finish, multicast control instruction unit 62a paired domination number is controlled according to sending part 62b, send by message the information of communication capacity that represents each handover base station candidate BTS 2～BTS 4 that obtains, with representing that the information of this communication capacity determines multicast transfer rate.

After the transfer rate of multicast is determined, multicast control instruction unit 62a carries out multicast instruction to multicast portion 43, and, input multicast transfer rate to transfer rate adjustment part 45.Thus, multicast portion 43 copies and is input to transfer rate to grouping and adjusts buffer part 44a～44c.In addition, multicast portion 43 is in order to distinguish grouping and the common grouping of multicast, to multicastapackets attach identifier.

Transfer rate adjustment part 45 is according to the multicast transfer rate for each handover base station candidate BTS 2, BTS 3, BTS 4, adjust buffer part 44a～44c from transfer rate and read grouping, via sending buffer part 47a～47c to each handover base station candidate BTS 2, BTS 3, BTS 4 multicasts.

With above-mentioned multicast concurrently, Handoff Control portion 61 determines handover base stations (supposition base station BTS 2 is handover base stations).Next, Handoff Control portion 61 carries out radio bearer setting request (RB Setup request) to this base station BTS 2.Then, set while replying (RB Setup replys) receiving radio bearer from base station BTS 2, mobile terminal MS is carried out to hand-off request (HO instruction).Thus, mobile terminal MS is carried out the handover from base station BTS 1 to base station MTS 2, sends handover reply after execution handover to base station BTS 2.

Base station BTS 2 is replied the grouping that sends institute's multicast and keep to mobile terminal MS by handover, and, send data transmission requests to mobile controller MCA.Mobile controller MCA stops multicast by data transmission requests, and, send the grouping receiving from IP network to mobile terminal MS via base station BTS 2.Thus, base station BTS 2 sends handover to base station BTS 1 and completes notice, and the multicast control instruction unit 62a instruction of base station BTS 1 abandons to not being selected as the handover base station candidate BTS 3 of handover base station, the grouping of BTS 4 multicasts.

According to the 2nd embodiment, can enumerate constructing of mobile communication system compared with the 1st embodiment and become simple feature.That is, in the 1st embodiment, need mobile controller and base station to carry out linkedly multicast transfer control, but can carry out separately multicast transfer control by base station in the 2nd embodiment.

(C) the 3rd embodiment

(a) the 1st mode of the 3rd embodiment

In the 1st, the 2nd embodiment, to suppose and start from handover till finish, transfer rate when multicast does not change.But, because the communication conditions moment of base station changes, so the communication capacity variation of base station in handover way sometimes.The 3rd embodiment is the embodiment that considers the situation of the communication capacity variation of base station in handover way, and mobile controller and base station have the structure shown in Fig. 2, Fig. 3.

Figure 20 is the diagrammatic illustration figure of the 3rd embodiment, and mobile controller MCA is positioned at the upper strata of base station BTS i.Mobile controller MCA is because moving of mobile terminal MS carried out Handoff Control, current to handover base station candidate BTS 2, BTS 3, BTS 4 multicastapackets.Under above-mentioned state, the communication capacity of handover base station candidate BTS 4 reduces, when become due to buffer overflow produce grouping abandon state time, or when Radio Resource is not enough, or cannot meet the QoS of mobile terminal request time, mobile controller MCA stops to the multicast of handover base station candidate BTS 4.

Figure 21 is the state in handover way, and 2 handover base station candidate BTS 2, BTS 4 are shown.BF is buffer, represents the buffer size of each base station with BF 2, BF 4, represents idle component by white.RM is Resource Manager, represents the stock number (for example frequency band) of each base station with RM 2, RM 4, represents the stock number (can service band) of unused portion by white.

Suppose that handover base station candidate BTS 4 can guarantee buffer capacity in the time that the multicast of data A starts, but cannot utilize Radio Resource in the multicast way of this data A.In the time that request level is newly connected to handover base station candidate BTS 4 higher than the mobile terminal of the QoS of the mobile terminal MS in communication, produce above-mentioned condition.This is because will cause inadequate resource (frequency band deficiency) to the mobile terminal priority allocation Radio Resource of the higher QoS of request.In the time of inadequate resource, the mobile terminal MS that handover base station candidate BTS 4 cannot accommodate in communication.

Figure 22 illustrates and stops to the state of the multicast control of handover base station candidate BTS 4 because of inadequate resource.

In order to carry out the control that stops of multicast because of inadequate resource, send the communication capacity report message shown in table 4 to mobile controller.

(table 4)

The communication capacity report message that base station sends adaptively

	BTS 4
		(1) buffer capacity	192Kb
(2) resource idle condition	0
		(3) could guarantee QoS	×

In addition, according to the form of Fig. 7, this communication capacity report message is as shown in table 5.

(table 5)

Communication capacity report message

00000100

00001000

111000000001

10

00

00

The mobile controller MCA identification that receives above-mentioned communication capacity report message cannot be guaranteed the situation of Radio Resource, removes base station BTS 4, and stop multicast transmission from the candidate of handover base station, notifies stopping of this multicast to base station BTS 4.In addition, together with multicast expiry notification, mobile controller MCA instruction base station BTS 4 abandons the grouping that multicast completes.Abandon instruction by implement grouping to the control message of base station BTS 4 transmission tables 6.

(table 6)

The control message (investigation request is not carried out in × expression) that grouping abandons

	BTS 4
		(1) buffer capacity	×
(2) resource idle condition	×
		(3) could guarantee QoS	×
(4) carry out abandoning of grouping	1

In addition, according to the form of Fig. 7, the control message that grouping abandons is as shown in table 7.

(table 7)

The control message that grouping abandons

00001000

00000100

00

00

00

11

By above control, even stop to the multicast transmission of base station BTS 4, mobile controller MCA also continues to base station BTS 4 handover base station candidate BTS 2 in addition, the data A that BTS 3 multicasts arrive from upper strata.

Figure 23 be the 3rd embodiment Handoff Control sequential want portion's key diagram, illustrate from the transmission of the message (table 1) of communication capacity investigation use and be timed to the sequential that multicast continues.

After handover base station candidate determines, mobile controller MCA sends reception by message and obtains the information of communication capacity that represents each handover base station candidate BTS 2～BTS 4, and use represents that the information of this communication capacity determines multicast transfer rate.

After the transfer rate of multicast is determined, mobile controller MCA starts multicast.In this multicast, handover base station candidate BTS 4, in the time of the variation that communication capacity detected, sends the communication capacity report message shown in table 4 to mobile controller MCA.In the time receiving this communication capacity report message, mobile controller MCA stops the multicast transmission to base station BTS 4, indicates grouping to abandon to the control message of base station BTS 4 transmission tables 6.After, mobile controller MCA continues to transmit to handover base station candidate BTS 2, BTS 3 multicasts the grouping arriving from upper strata.Later sequential is identical with Fig. 4.

As mentioned above, according to the 1st mode of the 3rd embodiment, by removing handover base station candidate the sending destination transmitting from multicast at once, and abandon the grouping to the base station multicast of removing before this, thereby can more effectively utilize Internet resources.

(b) the 2nd mode of the 3rd embodiment

In above-mentioned the 1st mode, mobile controller MCA removes this base station from multicast sending destination because handover base station candidate's communication capacity reduces, and, stop the multicast transmission to this base station.But, exist Radio Resource again to produce the free time, handover base station candidate BTS4 becomes the possibility that can accommodate mobile terminal MS.Therefore, in the 2nd mode of the 3rd embodiment, in the time causing utilizing the Radio Resource of base station BTS 4 due to communication capacity reduction, not from multicast sending destination, remove at once and stop multicast transmission, but the transfer rate of multicast is set as to 0, can in the time that recovering, communication capacity carry out thus multicast.

Figure 24 is the diagrammatic illustration figure of the 2nd mode of the 3rd embodiment, illustrates when Radio Resource as handover base station candidate BTS 4 in the multicast way at data A is not enough, the transfer rate of the multicast to base station BTS 4 is made as to 0 state.

Because the data A arriving from IP network is sent successively, so be not detained data in the transfer rate of mobile controller MCA is adjusted buffer part 14a.On the other hand, owing to being made as 0 to the multicast transfer rate of handover base station candidate BTS 4, be trapped in transfer rate so the data A arriving from IP network is not sent out and adjust buffer part 14c.But, in the time that the communication capacity of handover base station candidate BTS 4 is recovered, send the data that are trapped in transfer rate adjustment buffer part 14c to this base station BTS 4.

Figure 25 be the 2nd mode Handoff Control sequential want portion's key diagram, illustrate from the transmission of the message (table 1) of communication capacity investigation use and be timed to the sequential that multicast continues.

After handover base station candidate determines, mobile controller MCA sends reception by message and obtains the information of communication capacity that represents each handover base station candidate BTS 2～BTS 4, and use represents that the information of this communication capacity determines multicast transfer rate.After the transfer rate of multicast is determined, mobile controller MCA starts multicast.In this multicast, handover base station candidate BTS 4, in the time of the variation that communication capacity detected, sends the communication capacity report message shown in table 8 to mobile controller MCA.

(table 8)

Communication capacity report message

	BTS 4
		(1) buffer capacity	0Kb
(2) resource idle condition	1
		(3) could guarantee QoS	×

In addition, according to the form of Fig. 7, the grouping of communication capacity report message is as shown in table 9.

(table 9)

Communication capacity report message

00000100

00001000

100000000000

11

00

00

In the time receiving this communication capacity report message, because resource idle condition is that " 1 " (being " 0 " in table 4) and buffer capacity are 0Kb, so mobile controller MCA is made as 0 by the multicast transfer rate to base station BTS 4.

After, mobile controller MCA continues the grouping arriving from upper strata to handover base station candidate BTS 2, BTS 3 multicasts.Later sequential is identical with Fig. 4.

According to the 2nd mode of the 3rd embodiment, in the situation that communication capacity reduces, multicast transfer rate is made as to 0, in the time that communication capacity is recovered, restore transfer rate, thereby can continue multicast.

(c) the 3rd mode of the 3rd embodiment

In the 2nd mode, illustrate because communication capacity reduces and cause handover base station candidate BTS 4 cannot accommodate the situation of mobile terminal MS.But handover base station candidate BTS 4 by reducing the transfer rate that mobile terminal MS is provided, guarantees the bandwidth for this mobile terminal MS sometimes, can accommodate thus mobile terminal MS.Figure 26 is the summary description figure of the 3rd mode of the 3rd embodiment, illustrate that mobile controller MCA is made as the transfer rate of the multicast to base station BTS 4 state of the transfer rate corresponding with the Radio Resource of this base station in the time that the Radio Resource of handover base station candidate BTS 4 in the multicast way at data A reduces.

In the 2nd mode, the transfer rate of multicast is made as to 0Kb/s and on surface, stops multicast.But in the 3rd mode, the transfer rate (for example changing to 64Kb/s from 384Kb/s) mobile terminal BS being provided by reducing base station BTS 4, continues multicast.

The sequential of the 3rd mode is identical with Figure 25, but the report message difference that base station BTS 4 sends to mobile controller MCA.; in the 2nd mode; as shown in table 8; the value of buffer capacity is 0Kb; but in the 3rd mode; as shown in table 10, for during being received in the 500ms as handoff time for example, the data of sending with the transfer rate of 64Kb/s, buffer capacity is made as to the current of base station BTS 4 can service band 32Kb.

(table 10)

Communication capacity report message

	BTS 4
		(1) buffer capacity	32Kb
(2) resource idle condition	1
		(3) could guarantee QoS	×

In addition, according to the form of Fig. 7, above-mentioned communication capacity report message is as shown in table 11.

(table 11)

Communication capacity report message

00000100

00001000

100100000000

11

00

00

Because the data A arriving from IP network is sent successively, so be not detained data in the transfer rate of mobile controller MCA is adjusted buffer part 14a.On the other hand, owing to being below the input speed of data A to the multicast transfer rate of handover base station candidate BTS 4, being trapped in transfer rate so the data A corresponding with its difference is not sent out and adjusting in buffer part 14c.

According to the 3rd mode of the 3rd embodiment, in the case of handover base station candidate's communication capacity reduces, multicast transfer rate is made as to value corresponding to the communication capacity remaining with this base station candidate, can continue thus multicast, even in the situation that this handover base station candidate is selected as handover base station, also can communicate with mobile terminal.

(D) the 4th embodiment

(a) the 1st mode

In the 1st embodiment, suppose TCP as communication protocol end to end.In the 4th embodiment, conduct communication protocol is end to end described, suppose the situation for the UDP (User Datagram Protocol, User Datagram Protoco (UDP)) of real time communication.Suppose that mobile terminal MS carries out the stream communication of 1Mb/s, and mobile terminal MS request meets the QoS of the transfer rate of 1Mb/s.

Figure 27 is multicast key diagram in the past, and Figure 28 is the multicast key diagram of the 4th embodiment, and 2 handover base station candidate BTS 2, BTS 4 are shown.At Figure 27, Tu28Zhong, BF is buffer, represents the buffer size of each base station with BF 2, BF 4, represents idle component by white.QM is QoS management manager, represents the enforceable QoS level in each base station with QM 2, QM 4.

In the past case of Figure 27, mobile controller MCA does not investigate handover base station candidate BTS 4 could provide the QoS of mobile terminal request.Therefore, in the case of cannot meeting the QoS of mobile terminal request, divide into groups to abandon to cause carrying out futile multicast because buffer overflows to produce as shown in Figure, vainly utilize Internet resources.

But according to the 4th embodiment, mobile controller MCA can obtain each handover base station candidate's communication capacity before multicast starts, identification handover base station candidate BTS 4 could provide the QoS of mobile body terminal request.Then, mobile controller MCA, in the time being judged as the QoS that mobile terminal request cannot be provided, removes handover base station candidate BTS4 from multicast destination, does not carry out the multicast of the data that transmit from the streaming server of communication object.Thus, can prevent from producing grouping and abandon in the situation that cannot meeting QoS, and can effectively utilize Internet resources.

(b) the 2nd mode

Cannot carry out, the stream communication of this mobile terminal as the 1Mb/s of QoS request, as long as reduce the quality of image or voice, just can maintaining stream communication in the case of the handover base station candidate of mobile terminal MS.In the 2nd mode, even if cannot meet the QoS of mobile terminal request, in the time being moved terminal request and maintaining stream communication, also carry out multicast with the transfer rate corresponding with the handover base station available QoS of candidate.

Figure 29 is the multicast key diagram of the 2nd mode of the 4th embodiment, to the additional same numeral of the part identical with Figure 28.The mobile controller MCA reference buffer capacity that handover base station candidate BTS 4 reports before handover starts, in the time of the stream of 64Kb/s, be judged to be to accommodate, transmit the data B with the transfer rate coding of 1Mb/s with the transfer rate of 64Kb/s to handover base station candidate BTS 1.Thus, mobile terminal MS receives data B with the transfer rate of 64Kb/s, the deterioration of the transfer rate of stream detected, and the two is reduced to 64Kb/s from 1Mb/s to make the speed of coding and transfer rate to streaming server notice.The data that send taking backward mobile controller MCA are the data C shown in Figure 29.

Mobile controller MCA, in the time that the transfer rate that data C detected is reduced to 64Kb/s, carries out multicast transmission in the timing of this detection to handover base station candidate BTS 2 and BTS 4.As mentioned above, before carrying out handover to handover base station candidate BTS 4, make the transfer rate reduction for the stream of mobile terminal MS, so even if be handed over to handover base station candidate BTS 4, mobile terminal MS also can receive the stream of 64Kb/s.

As mentioned above, before handover, can realize in the base station of large capacity/high-speed communication, can change adaptively in advance QoS, can after handover, carry out reliably thus stream communication, and can not cause that grouping abandons.

(E) effect of invention

According to the present invention, the multicast transfer rate while determining Handoff Control according to each handover base station candidate's communication capacity, so can realize the high speed handover that effectively utilizes Internet resources.

According to the present invention, can alleviate the deterioration of the throughput after handover.In addition, can provide at once the second best in quality communication.In addition, can increase the message capacity of entire system.

Claims (21)

1. a hand over control method for the base station in mobile communication system or mobile control station, this mobile communication system follows the movement of mobile terminal to change the Handoff Control of the base station of this communication of mobile terminal, it is characterized in that,

Described mobile control station is controlled multiple base stations,

Carry out described Handoff Control by the base station having communicated with described mobile terminal before described mobile control station or handover,

This hand over control method has following steps:

According to the candidate of selected 1 the above handover base station of communications status;

According to communication capacity, from the transmission condition of each handover base station candidate notice, control the transmission of identical communication data for each base station candidate, and transmit to each handover base station candidate; And

The communication data transmitting described in handover base station candidate from being confirmed as handover base station is sent to mobile terminal.

2. hand over control method according to claim 1, it is characterized in that, transmit in the step of identical communication data to each handover base station candidate described, described communication capacity is the buffer capacity of the buffer that has separately of described 1 above handover base station candidate, the transfer rate of determining separately communication data described in multicast for described 1 above handover base station candidate according to this buffer capacity, carries out multicast by described communication data to each handover base station candidate with this transfer rate.

3. hand over control method according to claim 1, it is characterized in that, transmit in the step of identical communication data to each handover base station candidate described, described communication capacity is the idle condition of described 1 above handover base station candidate Radio Resource separately, the transfer rate of determining separately communication data described in multicast for described 1 above handover base station candidate according to the idle condition of this Radio Resource, carries out multicast by described communication data to each handover base station candidate with this transfer rate.

4. hand over control method according to claim 1, it is characterized in that, transmit in the step of identical communication data to each handover base station candidate described, described communication capacity is described 1 above handover base station candidate enforceable service quality QoS separately, the transfer rate of determining separately communication data described in multicast for described 1 above handover base station candidate according to this enforceable QoS, carries out multicast by described communication data to each handover base station candidate with this transfer rate.

5. hand over control method according to claim 1, it is characterized in that, transmit in the step of identical communication data to each handover base station candidate described, obtain each handover base station candidate's communication capacity by described each handover base station candidate is inquired about to described communication capacity.

6. hand over control method according to claim 1, it is characterized in that, transmit in the step of identical communication data to each handover base station candidate described, for each preservation of each handover base station candidate data corresponding with the difference of the communication data speed of inputting from network and multicast speed.

7. hand over control method according to claim 1, is characterized in that, transmits in the step of identical communication data, in order to distinguish grouping and the common grouping of multicast, to multicastapackets attach identifier described to each handover base station candidate.

8. hand over control method according to claim 1, it is characterized in that, transmit in the step of identical communication data to each handover base station candidate described, in the multicast way of transmitting described identical communication data, the variation of described more than 1 handover base station candidate communication capacity is separately detected, change adaptively the transfer rate of the handover base station candidate's who changes for communication capacity multicast according to this communication capacity after changing, with this transfer rate, described communication data is carried out to multicast to this handover base station candidate, or from the sending destination of multicast, remove the handover base station candidate of communication capacity variation and stop multicast.

9. hand over control method according to claim 8, is characterized in that, remove described handover base station candidate from the sending destination of multicast time, notice abandons the grouping that is attached with the identifier that multicastapackets uses.

10. hand over control method according to claim 9, is characterized in that, described handover base station candidate abandons the grouping that is attached with described identifier after discard notification receiving grouping.

Mobile controller in 11. 1 kinds of mobile communication system, this mobile communication system follows the movement of mobile terminal to change the Handoff Control of the base station of this communication of mobile terminal, it is characterized in that,

Described mobile controller is controlled multiple base stations, and this mobile controller has:

Handover base station candidate's determination portion, it is according to the candidate of selected 1 the above handover base station of communications status;

Transport unit, it, is controlled the transmission of identical communication data, and transmits to each handover base station candidate from the transmission condition of each handover base station candidate notice according to communication capacity for each base station candidate; And

Handover base station determination portion, it is defined as handover base station by 1 in described 1 above handover base station candidate.

12. mobile controllers according to claim 11, it is characterized in that, the data that described each handover base station candidate preserves institute's multicast, and the handover base station candidate who is confirmed as handover base station sends the communication data of preserving to mobile terminal.

13. mobile controllers according to claim 11, it is characterized in that, the buffer capacity of the buffer that described transport unit has described 1 above handover base station candidate is separately considered as described communication capacity, the transfer rate of determining separately communication data described in multicast for described 1 above handover base station candidate according to this buffer capacity, carries out multicast by described communication data to each handover base station candidate with this transfer rate.

14. mobile controllers according to claim 11, it is characterized in that, the idle condition of described 1 above handover base station candidate Radio Resource is separately considered as described communication capacity by described transport unit, the transfer rate of determining separately communication data described in multicast for described 1 above handover base station candidate according to the idle condition of this Radio Resource, carries out multicast by described communication data to each handover base station candidate with this transfer rate.

15. mobile controllers according to claim 11, it is characterized in that, described 1 above handover base station candidate enforceable service quality QoS is separately considered as described communication capacity by described transport unit, the transfer rate of determining separately communication data described in multicast for described 1 above handover base station candidate according to this QoS, carries out multicast by described communication data to each handover base station candidate with this transfer rate.

16. mobile controllers according to claim 11, is characterized in that, described transport unit obtains each handover base station candidate's communication capacity by described each handover base station candidate is inquired about to described communication capacity.

17. mobile controllers according to claim 11, is characterized in that,

Described transport unit has:

Transfer rate determination portion, it is according to each handover base station candidate's communication capacity, determines the transfer rate of communication data described in multicast; And

Transfer rate adjustment part, its with described definite transfer rate to described more than 1 handover base station candidate communication data described in multicast separately,

This transfer rate adjustment part has buffer, and this buffer is for each preservation of described 1 above handover base station candidate data corresponding with the difference of the transfer rate of the communication data speed of inputting from network and described multicast.

18. mobile controllers according to claim 11, is characterized in that, described transport unit is in order to distinguish grouping and the common grouping of multicast, to multicastapackets attach identifier.

19. mobile controllers according to claim 11, it is characterized in that, when described transport unit detects the variation of the communication capacity in described handover base station candidate in multicast way, change adaptively the transfer rate for described handover base station candidate's multicast according to this communication capacity after changing, or from the sending destination of multicast, remove described handover base station candidate and stop multicast.

20. mobile controllers according to claim 19, is characterized in that, described transport unit in the time removing described handover base station candidate from the sending destination of multicast, and notice abandons the grouping that is attached with the identifier that multicastapackets uses.

21. 1 kinds of mobile communication system, it has mobile terminal and follows the movement of this mobile terminal to change the mobile controller of the Handoff Control of the base station of this communication of mobile terminal, it is characterized in that,

Described mobile controller is controlled multiple base stations, and described mobile controller has:

Handover base station candidate's determination portion, it is according to the candidate of selected 1 the above handover base station of communications status;

Transport unit, it, is controlled the transmission of identical communication data, and transmits to each handover base station candidate from the transmission condition of each handover base station candidate notice according to communication capacity for each base station candidate; And

Handover base station determination portion, it is defined as handover base station by 1 in described 1 above handover base station candidate,

Described mobile terminal has receiver, and this receiver receives the described communication data sending from the described handover base station candidate who is defined as handover base station.