CN101232732B - Method for switching boundary in multi-transmission type code division multiple access system - Google Patents
Method for switching boundary in multi-transmission type code division multiple access system Download PDFInfo
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- CN101232732B CN101232732B CN2008100093551A CN200810009355A CN101232732B CN 101232732 B CN101232732 B CN 101232732B CN 2008100093551 A CN2008100093551 A CN 2008100093551A CN 200810009355 A CN200810009355 A CN 200810009355A CN 101232732 B CN101232732 B CN 101232732B
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Abstract
The invention discloses a method of the boundary switch in multi-transport-type Code Division Multiple Access (CDMA) system, which comprises the following steps: when a mobile station detects that a pilot strength from the cell neighboring the mobile station cell is up to the soft handoff threshold, the mobile station reports a Pilot Strength Measurement Message containing the information of the neighboring cell to the base station. The base station obtains the attribute information of the mobile station cell and the neighboring cell from the mobile station. If both cells are of the same transport type, the mobile station is informed of an execution of the soft handoff. If not, the mobile station is informed of an execution of the hard handoff. The invention solves the problem of the failure of the soft handoff due to the different transport delay and achieves a high-quality switch of the mobile station in a mixed network consisting of cells of different transport type through the judgment of the cell transport attribute of the base station controller and the flexible adoption of the soft handoff process and the hard handoff process, which reduces the disconnection rate and improves the network quality and the user experience.
Description
Technical field
The present invention relates to the cellular CDMA technology, specifically, relate to the method that switch on the border in a kind of many transport-types code division multiple access system.
Background technology
Soft handover is one of key technology of cellular CDMA (CDMA, Code Division Multiple Access) system.So-called soft handover is exactly when travelling carriage need be with a new base station communication, does not interrupt earlier and the getting in touch of former base station.Soft handover can only carry out between the CDMA Channel of same frequency, and it has played the diversity effect of Traffic Channel at the intersection of two base station overlay areas, can significantly reduce like this owing to switch the call drop that causes, and improve power system capacity.Direct-cut operation then is getting in touch of travelling carriage interruption earlier and former base station, gets in touch at the appointed time interior and new again base station.Direct-cut operation generally occurs in two minizones of cross base station controller (BSC, Base Station Controller), or the minizone of two different frequencies.Direct-cut operation can't provide diversity gain, and success rate is also low than soft handover.
The Soft Handover Algorithm of IS95 agreement regulation is roughly as follows:
(1) find that when travelling carriage the intensity of new pilot tone reaches soft handover and adds thresholding T_ADD, travelling carriage sends a Pilot Strength Measurement Message, and forwards this pilot tone to the candidate pilot set.
(2) base station sends a switch indicating information.
(3) travelling carriage forwards this pilot tone effective pilot set to and sends a handoff completion message.
(4) pilot frequency intensity drops to soft handover and goes below the thresholding T_DROP, and travelling carriage starts to switch and removes timer.
(5) switch and to remove timer and expire, travelling carriage sends a Pilot Strength Measurement Message.
(6) base station sends a switch indicating information.
(7) pilot tone is moved on to the adjacent pilot frequencies collection and sends the handoff completion message direct-cut operation from effective pilot tone then generally is pilot frequency intensity relative value comparison active set and the Candidate Set to travelling carriage, carries out switch decision according to the thresholding of configuration.In present system, the same frequency sector under the same BSC generally all is that judgement is soft handover.
Selector (SDU, Service Data Unit) is that the traffic frame in the CDMA2000 system is selected distribution module, is responsible for the traffic frame of each soft handover legs is carried out multiplexing distribution of forward direction and the selection of inverse demultiplexed frame, thereby realizes soft handover gain.SDU has distributed a reverse traffic frame buffer zone for each soft handover legs, selects a road best traffic frame according to frame number and error sign ratio, sends to mobile switching centre through vocoder.Realize the reverse frames selection in the soft handover, just require the time-delay of each soft handover legs in the allowed band of buffering area, in general, to consider and to handle time-delay that this buffering area can not be too big, at most about 8 frames (20 milliseconds of frames).
So just have a problem, it is too big that the time delay of two soft switching links can not differ, otherwise SDU can't carry out normal frame selection and distribution to the traffic frame of two branch roads, causes soft handover in fact can't carry out, and further causes call drop.A kind of typical scene is exactly the situation of ABIS satellite transmits.
Physical connection between base station controller (BSC) and base station transceiver (BTS, Base Transceiver System) often is called the ABIS link.Because BTS generally is distributed in each corner of the area of coverage, BSC is positioned at central machine room, is separated by often tens kilometers, even the hundreds of kilometer, and the ABIS link generally needs transmission system to support.Regional easily in transfer ratio than prosperity, adopt optical transport network often, because characteristics such as the time delay of optical transmission and shake are all fine, be fit to very much the synchronous requirement of cdma system.But in some backward areas and specific environment, such as Africa and desert area, because the deficiency of transfer resource, the ABIS link has adopted the mode of satellite transmits in networking, to realize the quick networking of cdma system.
The characteristics of satellite transmits are that time delay is big, about 270 milliseconds of One Way Delay, and up-downgoing is above 500 milliseconds.That is to say that the ABIS time delay of cdma system will be above 500 milliseconds.In actual applications, there are the situation about using of mixing in satellite transmits and Optical Fiber Transmission.A kind of networking embodiment for example shown in Figure 1, BTS1 and BTS2 are base station transceiver 101 among the figure, BTS1 is connected with base station controller 104 with satellite 103 by optical fiber switching system 102 respectively with BTS2.Like this, in satellite transmits sub-district and ordinary optic fibre transmission adjacent forntier region, sub-district, just there is the switching problem of satellite transmits sub-district and Optical Fiber Transmission sub-district.Because both ABIS time delays differ greatly, selector can't carry out the selection of buffer memory and best service frame to the reverse frames that comes on two soft handover legs, and this just causes in the frontier district can't realize normal soft handover, causes call drop.For example, in the embodiment shown in fig. 1, when travelling carriage will switch, the problems referred to above will appear in the sub-district of BTS1 and BTS2 covering.
At present, for this situation, general way is the isolated island base station with the satellite transmits plot planning exactly as far as possible, do not have handoff relation each other, but this has just reduced network quality.Also may exist other many transport-types code division multiple access system that same problem is arranged in the application.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of minizone at different chain-circuit time delays and realizes the method that switch on the border, to avoid the call drop of travelling carriage at handoff procedure, improves network service quality and user impression.
In order to address the above problem, the invention provides the method that switch on the border in a kind of many transport-types code division multiple access system, may further comprise the steps:
The pilot frequency intensity that travelling carriage detects the place adjacent cells of cells reaches the soft handover thresholding, reports pilot strength measurement report message to the base station, comprises the information of this neighbour sub-district in this message;
The base station obtains the attribute information that sub-district, travelling carriage place and pilot frequency intensity reach this neighbour sub-district of handoff threshold;
If sub-district, travelling carriage place is similar transmission sub-district with this neighbour sub-district, the notice travelling carriage is carried out soft handover; If sub-district, travelling carriage place is not similar transmission sub-district with this neighbour sub-district, the notice travelling carriage is carried out direct-cut operation.
Further, described many transport-types comprise satellite transmits and Optical Fiber Transmission at least.
Further, described travelling carriage forwards the pilot tone of this neighbour sub-district to the candidate pilot set after the base station reports pilot strength measurement report message.
Further, described base station obtains the attribute information of the sub-district adjacent with it, sub-district at travelling carriage place by database configuration.
Further, described base station obtains the attribute information of the sub-district adjacent with it, sub-district at travelling carriage place by the automatic detection of system.
Further, if sub-district, travelling carriage place is not similar transmission sub-district with this neighbour sub-district, the step that the notice travelling carriage is carried out direct-cut operation specifically comprises: base station controller judges whether to carry out direct-cut operation according to relative handoff threshold algorithm, if desired, the notice travelling carriage is carried out direct-cut operation; If do not need, proceed to detect and judge.
Further, described travelling carriage is after the base station reports pilot strength measurement report message, and the time delay of ABIS link is regularly detected in described base station, if the chain-circuit time delay difference of two soft switching subzones surpasses a predefined thresholding, the notice travelling carriage is carried out direct-cut operation.
Further, soft handover or direct-cut operation are carried out by issue general switch indicating information notice travelling carriage to travelling carriage in described base station.
It is the isolated island base station that the present invention need not the satellite transmits plot planning, by the judgement of base station controller (BSC) to the cell transmission attribute, adopt soft handoff procedure and direct-cut operation flow process flexibly, solved because the soft handover failure problem that the propagation delay time difference causes, realized that travelling carriage carries out high-quality switching in the hybrid network that the sub-district of different transport-types is formed, can reduce system's cutting off rate, improve network quality and user's impression.
Description of drawings
Fig. 1 is the embodiment schematic diagram of a kind of Optical Fiber Transmission and satellite transmits mixed networking;
Fig. 2 moves forward into the scene schematic diagram that row bound switches for travelling carriage in the network of mixed networking;
Fig. 3 is the schematic flow sheet of border changing method in the satellite transmits code division multiple access system of the present invention.
Embodiment
The present invention selects the switching mode that adapts by the transport-type of the sub-district of judge to participate in switching, thereby solves when travelling carriage during in the switching of the minizone of different transport-types, causes the problem of call drop easily.
The invention will be further described below in conjunction with the drawings and specific embodiments, can be implemented so that those skilled in the art can better understand the present invention also, but illustrated embodiment is not as a limitation of the invention.
As shown in Figure 2, in the network of mixed networking, move forward into the scene schematic diagram that row bound switches for travelling carriage 200.Wherein, the sub-district that sub-district A covers for the satellite transmits base station, sub-district B is the sub-district that the Optical Fiber Transmission base station is covered.Travelling carriage 200 initially is arranged in sub-district A, and in communication process, travelling carriage 200 is moved to sub-district B by sub-district A, switches so the border will take place.
As shown in Figure 3, be the schematic flow sheet of border changing method in the satellite transmits code division multiple access system of the present invention.
Referring to Fig. 2 and Fig. 3, when travelling carriage was moved by sub-district A and sub-district B, the flow process of carrying out switching on the border was:
Step 301: after the pilot frequency intensity that travelling carriage detects sub-district B reached soft handover and adds thresholding T_ADD, travelling carriage reported pilot strength measurement report message (PSMM) to the base station, wherein with the information of sub-district B; Simultaneously, travelling carriage is put into Candidate Set with sub-district B;
Step 302: after PSMM message is received in the base station, take out the information of sub-district B, in configuration database, search, obtain the sub-district A that participates in switching and the attribute information of sub-district B; The base station also can obtain the attribute information of sub-district A and sub-district B by the automatic detection of system;
Step 303: the base station judges whether the sub-district A that participates in switching is the sub-district of similar transmission with sub-district B, and promptly whether sub-district A and sub-district B all are the Optical Fiber Transmission sub-districts, perhaps all are the satellite transmits sub-districts, if, execution in step 307; If sub-district A is different with the transmission property of sub-district B, for example in the present embodiment, sub-district A is the satellite transmits sub-district, and sub-district B is the Optical Fiber Transmission sub-district, and then execution in step 304;
Step 304: the switch decision of direct-cut operation is carried out in the base station, classifies the satellite transmits sub-district and the Optical Fiber Transmission sub-district that participate in switching as a set respectively;
Step 305: the base station judges whether to carry out direct-cut operation according to relative handoff threshold algorithm, if desired, and execution in step 306; If do not need, do not deal with; In the selection of handoff threshold, preferably suitably deflection is used the Optical Fiber Transmission sub-district, to improve network performance and user impression;
Step 306: the base station is judged need carry out direct-cut operation, issues general switch indicating information (UHDM) to travelling carriage, and the indication travelling carriage is finished the direct-cut operation from sub-district A to sub-district B, and travelling carriage is finished direct-cut operation after receiving UHDM message.
Step 307: switch decision is carried out according to common soft handoff in the base station, eligiblely then sub-district A and sub-district B are put into active set, send general switch indicating information (UHDM) to travelling carriage, the guiding travelling carriage carries out soft handover, and travelling carriage is finished soft handover after receiving UHDM message.
In the step 302 in the present embodiment, after the PSMM message that travelling carriage sends is received in the base station, can regularly detect the ABIS chain-circuit time delay of two sub-districts that participate in switching, and execution in step 307: whether the ABIS chain-circuit time delay difference of judging two sub-districts that participate in switching reaches a thresholding that preset, configurable, if reach, execution in step 307, travelling carriage is implemented direct-cut operation; If do not reach, execution in step 307, travelling carriage is implemented soft handover.
In the step 305, the base station is according to relative handoff threshold algorithm, judge whether that a kind of method that need carry out direct-cut operation is: judge in the soft handover set pilot energy and with the direct-cut operation set in pilot energy and magnitude relationship, when " pilot energy in the direct-cut operation set and＞pilot energy in the soft handover set and * relative threshold " time, be judged as direct-cut operation.When setting relative threshold, the direct-cut operation relative threshold that can switch to the Optical Fiber Transmission base station from the satellite transmits base station is set to a smaller value, making can be than being easier to carry out direct-cut operation, and when switching to the satellite transmits base station from the Optical Fiber Transmission base station, can be set to a bigger value by the direct-cut operation relative threshold, make communication be retained in the Optical Fiber Transmission base station as far as possible, thereby realize described suitable deflection use Optical Fiber Transmission sub-district, to improve the purpose of network performance and user impression.
The above embodiment is the preferred embodiment that proves absolutely that the present invention lifts, and protection scope of the present invention is not limited thereto.Being equal to that those skilled in the art are done on basis of the present invention substitutes or conversion, all within protection scope of the present invention.Protection scope of the present invention is as the criterion with claims.
Claims (8)
1. the method that switch on the border in the transport-type code division multiple access system more than a kind is characterized in that, may further comprise the steps:
The pilot frequency intensity that travelling carriage detects the place adjacent cells of cells reaches the soft handover thresholding, reports pilot strength measurement report message to the base station, comprises the information of this neighbour sub-district in this message;
The base station obtains the attribute information that sub-district, travelling carriage place and pilot frequency intensity reach this neighbour sub-district of handoff threshold;
If sub-district, travelling carriage place is similar transmission sub-district with this neighbour sub-district, the notice travelling carriage is carried out soft handover; If sub-district, travelling carriage place is not similar transmission sub-district with this neighbour sub-district, the notice travelling carriage is carried out direct-cut operation.
2. the method for claim 1 is characterized in that,
Described many transport-types comprise satellite transmits and Optical Fiber Transmission at least.
3. the method for claim 1 is characterized in that,
Described travelling carriage forwards the pilot tone of this neighbour sub-district to the candidate pilot set after the base station reports pilot strength measurement report message.
4. as claim 1,2 or 3 described methods, it is characterized in that,
Described base station obtains the attribute information of the sub-district adjacent with it, sub-district at travelling carriage place by database configuration.
5. as claim 1,2 or 3 described methods, it is characterized in that,
Described base station obtains the attribute information of the sub-district adjacent with it, sub-district at travelling carriage place by the automatic detection of system.
6. the method for claim 1 is characterized in that,
If sub-district, travelling carriage place is not similar transmission sub-district with this neighbour sub-district, the step that the notice travelling carriage is carried out direct-cut operation specifically comprises: base station controller is according to relative handoff threshold algorithm, judge whether to carry out direct-cut operation, if desired, the notice travelling carriage is carried out direct-cut operation; If do not need, proceed to detect and judge.
7. the method for claim 1 is characterized in that,
Described travelling carriage is after the base station reports pilot strength measurement report message, and the time delay of ABIS link is regularly detected in described base station, if the chain-circuit time delay difference of two soft switching subzones surpasses a predefined thresholding, the notice travelling carriage is carried out direct-cut operation.
8. as claim 1,6 or 7 described methods, it is characterized in that,
Soft handover or direct-cut operation are carried out by issue general switch indicating information notice travelling carriage to travelling carriage in described base station.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2008100093551A CN101232732B (en) | 2008-02-25 | 2008-02-25 | Method for switching boundary in multi-transmission type code division multiple access system |
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| CN2008100093551A CN101232732B (en) | 2008-02-25 | 2008-02-25 | Method for switching boundary in multi-transmission type code division multiple access system |
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| CN101232732B true CN101232732B (en) | 2011-03-16 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101873568B (en) * | 2009-04-21 | 2014-08-20 | 电信科学技术研究院 | Method and equipment for acquiring cell attribute |
| CN103124441B (en) * | 2011-11-21 | 2015-12-16 | 中兴通讯股份有限公司 | A kind of processing method of too long link delay of satellite site and device |
| CN104349407B (en) * | 2013-07-24 | 2018-03-09 | 北京信威通信技术股份有限公司 | A kind of method switched to strong signal base station |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1175179A (en) * | 1996-06-24 | 1998-03-04 | Ntt移动通信网株式会社 | Switching type judging method for code devision multiple access mobile communication system |
| CN1265253A (en) * | 1997-05-19 | 2000-08-30 | 北方电讯网络有限公司 | Boundary sector hard handoff trigger |
| CN1589583A (en) * | 2001-09-27 | 2005-03-02 | 高通股份有限公司 | Handoff method and apparatus with dual pilots in a communication system |
| WO2005122622A1 (en) * | 2004-06-07 | 2005-12-22 | Nortel Networks Limited | Handoffs and handoff selection in a wireless access network |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1175179A (en) * | 1996-06-24 | 1998-03-04 | Ntt移动通信网株式会社 | Switching type judging method for code devision multiple access mobile communication system |
| CN1265253A (en) * | 1997-05-19 | 2000-08-30 | 北方电讯网络有限公司 | Boundary sector hard handoff trigger |
| CN1589583A (en) * | 2001-09-27 | 2005-03-02 | 高通股份有限公司 | Handoff method and apparatus with dual pilots in a communication system |
| WO2005122622A1 (en) * | 2004-06-07 | 2005-12-22 | Nortel Networks Limited | Handoffs and handoff selection in a wireless access network |
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