CN1817052A - Method and apparatus for performing soft-handoff in a wireless communication system - Google Patents
Method and apparatus for performing soft-handoff in a wireless communication system Download PDFInfo
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Abstract
When performing a soft-handoff, a communication system (200) determines whether to engage in an analysis of a reverse link (254) associated with a base station (209) under consideration to be added to an active set of a mobile station (MS) (202). Upon determining not to analyze the reverse link, the communication system adds the base station to the active set without evaluating the associated reverse link. Upon determining to engage in a reverse link analysis, the communication system evaluates the reverse link in order to assure that a communication link (220) is not terminated, or dropped, as part of the soft-handoff until such time as the communication system may confirm that an acceptable quality reverse link is being added. The communication system then determines whether to add the base station to the active set based upon the evaluation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is the U.S. Patent Application Serial Number 10/439 of application on May 16th, 2003,743, (continuation-in-part) partly applied in the continuation of lawyer's document number CE11382R, and the interim pending application of the U.S., the sequence number that require on June 30th, 2003 to apply for are 60/483,807 priority, it is had by same applicant, and at this in conjunction with reference.
Technical field
The present invention relates generally to wireless communication system, more specifically relate to the soft handover in the wireless communication system.
Background technology
Wireless communication system is known and comprises polytype, comprises the land mobile wireless, cellular radio (comprising analog cellular, digital cellular, PCS Personal Communications System (PCS) and wide-band digital cellular systems), and other communication system types.For example in cellular radiotelephone communication systems, a plurality of communication cells are made up of one or more base station transceivers (BTS) usually, these base station transceivers are connected to one or more base station controllers (BSC) or central base station controller (CBSC), and form base station sub-system (BSS).BSC or CBSC are connected to mobile switching centre (MSC) conversely, and MSC provides BSS and such as the connection between the external network of PSTN (PSTN), and interconnecting to other BSS.Each BTS provides communication service for the travelling carriage (MS) be positioned at this BTS service coverage area by the communication resource, and these communication resources comprise the forward link that transmits a signal to MS, and from the reverse link of MS received signal.
The basis of wireless communication system be when MS within the overlay area and between can keep the ability of having set up that communicates to connect when mobile.In order to safeguard communicating to connect of having set up, developed " soft handover " technology that is used for code division multiple access (CDMA) communication system, MS can carry out the while with a plurality of BTS and effectively communicate by letter whereby.With each BTS of MS active communications all be a member among the MS " Active Set ", and transmit loaded service and receive loaded service to MS and from MS.When MS is mobile in communication system, from the MS Active Set, adds or deletion BTS, thereby guarantee that MS communicates by letter with at least one BTS all the time.
For example, Fig. 1 is the block diagram of prior art cdma wireless communication system 100.Communication system 100 comprises BSS 104, and it comprises a plurality of BTS 106-108, and wherein each all is connected to CBSC 110.BSS 104 is connected to MSC 114 and MSC 114 is connected to external network 116, and the communication between external network and BSS 104 and other BSS and the BSS 104 is provided.Communication system 100 further comprise current just with the MS 102 of BTS 106 and 107 active communications.That is, MS 102 be in BTS 106 and 107 " soft handover " in, BTS106 and 107 is the members among the MS 102 " Active Set ".As a member of MS 102 Active Sets, each among the BTS 106 and 107 is all kept the wireless communication link separately 120,130 with MS simultaneously.Every communication link 120,130 comprises forward link 122,132 separately, is used to transmit signal to MS 102, and reverse link separately 124,134, is used to receive the signal from MS.
Each BTS 106 in MS 102 Active Sets and 107 transmits identical bearer service and receives identical bearer service to MS and from MS.By providing a plurality of same signals that can transmit simultaneously to receive the BTS of same signals to MS 102 and from MS 102, communication system 100 has strengthened MS and has received from BSS 104 and can accept quality signal, and BSS receives the possibility that can accept quality signal from MS.For example, when each of BTS 106 and 107 all when MS 102 receives same number of frames, BTS determines that this received frame is acceptable or wrong, and transmit this frame and this frame is acceptable, promptly good, or wrong, promptly Shan Chu the designator of following is given CBSC 110.CBSC 110, particularly are included in selection and Dispatching Unit (SDU) 112 in the CBSC 110, a version of selective reception frame from the reception version of BTS 106 and 107, and the version that forwarding is selected is to MSC 114.
When MS 102 when move the overlay area relevant with BTS 108 or sector, the signal strength signal intensity increase of the pilot signal that MS 102 receives from BTS 108 through the forward link 142 relevant with BTS 108 will be identified as available communication link from the pilot signal of BTS 108 up to MS 102.In addition, because MS 102 leaves overlay area or the sector relevant with BTS 106, MS 102 reduces through the intensity of the pilot signal that forward link 122 receives from BTS 106, when MS 102 determines that communication links 120 no longer are available communication link till.MS 102 request communication systems 100 are added BTS 108 in the Active Set of MS then, promptly, the communication link 140 that foundation and BTS108 are associated, comprise forward link 142 and reverse link 144, as the active communication link that sends data to MS 102 and receive data from MS 102, and from Active Set, delete BTS 106, promptly stop communication link 120.Usually, MS 102 transmits the request of deletion BTS by Pilot Strength Measurement Message (PSMM).When receiving PSMM message, BSS 104 deletes BTS 106 from the Active Set of MS 102, and the communication link 120 between termination or deletion MS102 and the BTS 106.
Measure according to forward link, promptly the measurement of the pilot signal strength that receives through corresponding forward link such as the MS of MS 102 is determined to add from Active Set or deleting communication link 120,130,140 and corresponding BTS 106,107,108.That is, when adding and/or delete decision, in fact the performance with corresponding reverse link 124,134,144 is identical for the performance of communication system 100 supposition forward links 122,132,142.Yet when such as forward link 122,132,142 performance and corresponding reverse link when promptly the performance of each reverse link 124,134,144 is uneven, just problem occurred.For example, may experience return link interferences by the sector of certain BTS service, or and certain sector in each bar forward link and the reverse link propagation path of all be correlated with and decaying owing to the band separation between forward link and the reverse link is different.As a result, in some cases,, and add because strong forward link but have the communication link of more weak reverse link because more weak forward link may be deleted the communication link with strong reverse link.Reverse link when the communication link of deleting, for example the reverse link 124 of communication link 120 is used many reverse links of MS, for example reverse link 124,134, in unique reverse link preferably, and the reverse link of the communication link that adds, for example reverse link 144 of communication link 140, when quality was unacceptable, then the deleting communication link can cause call drop.
Therefore, before communication system determines that the reverse link circuit quality that adds can be accepted,, need guarantee not stop or the deleting communication link as the part of soft handover.
Description of drawings
Fig. 1 is the block diagram of prior art wireless communication system.
Fig. 2 is the block diagram according to the wireless communication system of the embodiment of the invention.
Fig. 3 is the logical flow chart by Fig. 2 communication system execution soft handover according to the embodiment of the invention.
Fig. 4 determines whether to carry out the logical flow chart of the method for reverse link analysis according to different embodiments of the invention by Fig. 2 communication system.
Fig. 5 carries out the logical flow chart of the method for reverse link analysis according to the embodiment of the invention by Fig. 2 communication system.
Fig. 6 is a logical flow chart of being carried out soft handover in accordance with another embodiment of the present invention by Fig. 2 communication system.
Embodiment
When having guaranteed to add second communication link during the soft handover with unacceptable reverse link for solving, demand with the not deleted method and apparatus of unique first communication link of accepting reverse link, a kind of communication system is provided, when carrying out soft handover, this system determines whether the reverse link relevant with considering to add to base station in the travelling carriage Active Set analyzed.When determining not carry out reverse link analysis, communication system is added the base station in the Active Set to, does not estimate relevant reverse link.When determining to carry out reverse link analysis, communication system is estimated this reverse link, thereby guarantees not stop or delete communication link as the part of soft handover, when communication system is confirmed to have added the acceptable reverse link of quality till.Communication system determines whether to add this base station in Active Set according to this evaluation then.When determining not add this base station in Active Set the time, communication system is the monitoring forward link relevant with MS further, with the communication link that determines whether to rethink this base station of interpolation and be associated with this base station in Active Set.
Usually, embodiments of the invention comprise a kind of method of carrying out soft handover in wireless communication system.This method comprises receiving adds the request of base station to the travelling carriage Active Set, and determines whether to analyze the reverse link relevant with this base station.When determining not analyze reverse link, this method further comprises adds this base station in Active Set and do not estimate this reverse link.When determining to analyze reverse link, this method further comprises estimates this reverse link, and when estimating reverse link, determines whether this base station is added in the Active Set according to evaluation result.
An alternative embodiment of the invention comprises a kind of equipment of carrying out soft handover in wireless infrastructure.This equipment comprises processor, consideration will be added the base station of travelling carriage Active Set to, determine whether to analyze the reverse link relevant with this base station, when determining not analyze reverse link, add the base station in Active Set and do not estimate reverse link, when determining to analyze reverse link, estimate reverse link, and when estimating reverse link, determine whether to add this base station in Active Set according to evaluation result.
Describe the present invention in detail with reference to figure 2-6.Fig. 2 is the block diagram according to the cdma wireless communication system 200 of the embodiment of the invention.Similar with communication system 100, communication system 200 comprises base station sub-system (BSS) 204, it comprises a plurality of base station transceivers (BTS) 206-209 (having shown 4), and each all is connected to controller 212, and controller 212 for example is base station controller (BSC) or central base station controller (CBSC).BSS 204 is connected to mobile switching centre (MSC) 260, MSC 260 be connected to external network 262 and external network is provided or other BSS (not shown) and BSS 204 between communication.BSS 204 and MSC 260 are called as the foundation structure of communication system 200 together.
Each of a plurality of BTS 206-209 and controller 212, preferably in controller 212, comprise and selecting and Dispatching Unit (SDU) 214, comprise processor 210 separately, 215, for example one or more microprocessors, microcontroller, digital signal processor (DSP), and the combination of other device of this kind known to a person of ordinary skill in the art.Each of a plurality of BTS 206-209 and controller 212 further comprise one or more storage devices 211,216, storage device 211 and 216 respectively with processor 210,215 link to each other, for example be random access storage device (RAM), dynamic RAM (DRAM), and/or read-only memory (ROM) or its equivalent are used to store the program that data and processor are carried out.Controller 212 further comprises the timer 218 that is connected to SDU 214.
Communication system 200 comprises that further while and a plurality of BTS 206-208 carry out the travelling carriage (MS) 202 of active communications.That is, MS 202 is in " soft handover " pattern with a plurality of BTS 206-208, and each of a plurality of BTS 206-208 all is a member of MS 202 " Active Set ".As a member of MS 202 Active Sets, each among a plurality of BTS 206-209 is kept the wireless communication link separately 220,230,240 with MS simultaneously.Every communication link 220,230,240 comprises and is used to transmit separately the forward link 222,232,242 of signal to MS 202, and is used to receive the reverse link separately 224,234,244 from the signal of MS.
Preferably, communication system 200 is code division multiple access (CDMA) communication systems, and wherein forward link 222,232,242,252 and reverse link 224,234,244,254 comprise many communication channels, such as access channel, control channel, paging channel and Traffic Channel.Reverse link 224,234,244,254 or every communication channel of forward link 222,232,242,252 comprise an orthogonal code, Walsh sign indicating number for example, this orthogonal code transmits with the frequency bandwidth identical with other link channels.Yet, those of ordinary skills recognize, communication system 200 can be according to radio telecommunications system operation arbitrarily, such as but not limited to, global mobile communication (GSM) communication system, time division multiple access (TDMA) communication system, frequency division multiple access (FDMA) communication system, or OFDM (OFDM) communication system.
When communication system 200 operated in the soft handoff mode, more than first frame that MS 202 sends received by reverse link 224,234,244 separately by among a plurality of BTS 206-208 in the MS Active Set each.Among a plurality of BTS 206-208 each is transmitted a plurality of frames of BTS reception then and is given controller 212, and further transmits one or more designators of a plurality of frame quality of indication reception.
One or more quality indicators that each BTS 206-208 transmits are to go up the reverse link quality metric of determining or determine about these a plurality of frames in the basis frame by frame according to BTS.For example, reverse link quality metric can be the frame error rate of determining about these a plurality of frames (FER), or based on about one or more frames of these a plurality of frames and definite bit error rate (BER), signal to noise ratio (snr), signal strength signal intensity, carrier-to-noise ratio (CIR) or Eb/Io than (energy per bit/interference power density (every hertz)).Those of ordinary skills recognize that many quality metrics are arranged, and can not deviate from the spirit and scope of the present invention in this use.
Quality indicator can comprise that reverse link quality metric maybe can be a designator of representing reverse link quality metric.For example, BTS can determine that the frame of this reception is acceptable or wrong according to each frame and frame quality metric.BTS embeds quality indicator in this frame header, it is acceptable promptly good that this quality indicator is indicated this frame, and still wrong is promptly deleted.BTS transmits the quality indicator of this frame and embedding then to controller 212.
When controller 212 when each of a plurality of BTS 206-208 receives a plurality of frames and relevant one or more quality indicator, controller will these one or more quality indicators in one or more storage arrangements 216 and being stored together of initiating that the BTS of these a plurality of frames and/or reverse link or communication link is associated, and have wherein received this a plurality of frames by these links.When each of a plurality of BTS 206-208 receives same number of frames, controller 212 is selected a frame then and the frame of selecting is forwarded to MSC 260 from the same number of frames that each BTS receives.Unless specialize at this, controller 212 is all preferably carried out by SDU 214 in all functions of this execution, is carried out by processor 215 specifically.
When MS is mobile in communication system 200, MS can towards with overlay area or sector that the BTS in the MS Active Set is not relevant, for example BTS 209, and leave and relevant overlay area or the sector of BTS in Active Set, for example BTS 206.As MS 202 during to BTS 209 motion, the signal strength signal intensity increase of the pilot signal that MS 202 receives through the forward link 252 relevant with BTS 209 will be identified as available communication link from the pilot signal of BTS 209 up to MS 202.In addition because MS 202 leaves BTS 206, MS 202 by and the signal strength signal intensity reduction that receives of BTS 206 relevant forward links 222 from the pilot signal of BTS 206, till MS 202 definite communication links 220 no longer are available communication link.At this moment, communication system 200 determines whether to carry out soft handover by deletion BTS 206 in the Active Set that adds BTS 209 and relevant communication link 250 to MS 202 and from the Active Set of MS 202 and relevant communication link 220 thereof.
Fig. 3 is communication system 200 determines whether to carry out the performed step of soft handover according to the embodiment of the invention a logical flow chart 300.When transmitting communication system, MS 202 adds a BTS, be in the Active Set of BTS 209 to MS, and the first relevant communication link 250 of foundation and BTS 209, comprise forward link 252 and reverse link 254, arrive communication system infrastructure as transferring data to MS 202 and reception from the request of the active communication link of the data of MS 202, specifically be BSS 204, and foundation structure is when this MS receive (302) this request, logical flow chart 300 beginnings.The 2nd BTS among the MS 202 further a plurality of BTS 206-208 that transmit in communication system deletion MS 202 Active Sets, be BTS 206, and termination or the deletion second communication link relevant with this BTS, be the foundation structure of the request of communication link 220 to communication system 200, specifically be BSS 204, and foundation structure receive (304) this request from this MS.Preferably, each adds the request of BTS 209 and/or communication link 250 and the request of deletion BTS 206 and/or communication link 220 uses Pilot Strength Measurement Message (PSMM) to transmit by MS 202, embeds the request of adding or deleting each BTS and/or communication link therein.
In order to ensure not stopping or delete second communication link 220, part as the soft handover execution, up to communication system 200 can confirm relevant with BTS 209, in the time of it may being added to new reverse link 254 in the Active Set and has acceptable quality till, all substitute by first communication link 250.Controller 212 determines whether (306) carried out reverse link analysis before the Active Set that adds BTS 209 to MS 202, promptly at this BTS of interpolation before the Active Set of MS 202, whether estimate the reverse link 254 relevant with BTS 209.
Controller 212 determines whether to carry out reverse link analysis or evaluation according to the quality of not considering at least one in the forward link 232,242 that Active Set member's its deletion, that be MS 202 BTS is relevant.When controller 212 was determined not carry out reverse link analysis, controller was carried out (308) soft handover, can at first not carry out reverse link analysis.That is, controller 212 BTS 209 and related communication link 250 thereof are added in the Active Set of MS 202 and from the Active Set of MS202 deletion BTS 206 and related communication link 220 thereof, and do not carry out reverse link analysis.By not carrying out reverse link analysis, minimized any delay relevant with adding required forward link 252.
When carrying out reverse link analysis when determine to carry out soft handover at step 306 controller 212 before, controller proceeds to execution (310) reverse link analysis.Reverse link analysis comprises estimates at least one relevant reverse link of considering it to be added in MS 202 Active Sets of BTS, be reverse link 254 and BTS 209, and after the soft handover execution, will be retained in the reverse link that the BTS in MS 202 Active Sets is correlated with, be reverse link 234,244 and BTS 207 and 208.According to reverse link analysis, controller 212 determines then whether (312) add in the Active Set of BTS 209 and related communication link 250 to MS 202 thereof.Logic flow 300 finishes.
With reference now to Fig. 4,, logical flow chart 400 has shown that according to various embodiments of the invention controller 212 determines whether to carry out the method for reverse link analysis in step 306.In one embodiment of the invention, when controller 212 is determined the forward link 232 that (402) are current and MS 202 is in soft handoff mode and can keeps when MS is in soft handoff mode in the incident of deletion BTS 206 and related communication link 220 from Active Set, in 242 during at least one forward link quality metric, logic flow 400 beginnings.Controller 212 compares forward link quality metric of (404) determining and the forward link quality metric threshold that is stored in controller 212 one or more storage arrangements 216 then.
In one embodiment of the invention, forward link quality metric is based on MS 202 and is in the soft handoff mode, an and definite comprehensive measurement of quality of all forward links 232,242 that after deletion possibility link 220 and interpolation link 250, keep in the soft handoff mode at MS.For example, controller 212 is determined the integrated signal intensity of all this kind forward links 232,242.Forward link quality metric and aggregate forward link quality metric threshold that controller 212 is relatively determined then.
In another embodiment of the present invention, controller 212 can by determine and MS 202 is co-located in the soft handoff mode and after deletion may link 220 and is added link 250 with the soft handover of MS in each bar forward link 232 of reservation still, 242 quality is determined forward link quality metric, and further determines best forward link quality from a plurality of definite forward link quality.Controller 212 is then with this forward link quality metric, and promptly best forward link quality and forward link quality metric threshold are relatively.
Forward link quality metric is known in this area.For example, forward link quality metric can be the frame error rate of determining according to a plurality of frames (FER), or based on the bit error rate (BER), signal to noise ratio (snr), signal strength signal intensity, carrier-to-noise ratio (CIR) or the Eb/Io that determine according to one or more frames than (energy per bit/interference power density (every hertz)).Those of ordinary skills will be appreciated that, known multiple quality metric can use and can not deviate from the spirit and scope of the present invention at this.
In one embodiment of the invention, MS 202 can be according to passing through forward link 232,242 signals that receive are determined forward link quality metric, and transmit this forward link quality metric to BSS 204 by the one or more BTS in the MS Active Set, specifically are controllers 212.Controller 212 is determined forward link quality metric according to the forward link quality metric that receives from MS 202 then.In another embodiment, MS measures the signal that MS receives by forward link 232,242, and measures BSS 204 by the one or more BTS transmission in the MS Active Set, specifically is controller 212.Controller 212 can be determined forward link quality metric according to the measurement that receives from MS 202 then.
When forward direction link quality metric and forward link quality metric threshold are more unfavorable, for example when the forward direction link quality metric is lower than this threshold value, think the forward link 232 that current and MS 202 is in soft handoff mode and keeps in the MS soft handoff mode, 242 is more weak, needs new forward link to be used for Active Set.As a result, when controller 212 determined that (406) forward link quality metric and threshold ratio are more unfavorable, controller 212 determined that further (408) do not carry out reverse link analysis and just carry out soft handover.That is, controller 212 adds in the Active Set of BTS 209 and related communication link 250 to MS 202 thereof and does not carry out reverse link analysis.By not carrying out reverse link analysis, and add required forward link 252 relevant delays and be minimized.Flow process 400 finishes.
When forward direction link quality metric and forward link quality metric threshold were more favourable, then current and MS 202 was in the soft handoff mode and one of forward link 232,242 of being retained in the MS soft handover is considered to acceptable.As a result, think to need not to add new forward link that promptly forward link 252, MS 202 just can keep communicating by letter of acceptable level with communication system 200 foundation structures.Therefore, not to be badly in need of new forward link, communication system 200 can be stood and added new forward link, and promptly forward link 252, relevant with reverse link analysis before delay.The result, when controller 212 is determined (406) when forward link quality metric is better than forward link quality metric threshold, controller 212 is further determined to carry out reverse link analysis before (410) are in determining whether to add the Active Set of BTS209 and related communication link 250 to MS 202 thereof.Controller 212 determines according to reverse link analysis whether (412) add in the Active Set of BTS 209 and related communication link 250 to MS 202 thereof then.Logic flow 400 finishes.
In another embodiment of the present invention, controller 212 determines whether that in step 306 method of carrying out reverse link analysis can further may further comprise the steps.Before step 402 was determined forward link quality metric, controller 212 determined that (414) current and MS 202 is in the communication link or the forward link quantity of soft handoff mode, the communication link of the active communications of promptly current participation and MS 202 or forward link quantity.Controller 212 compares (416) communication link or forward link quantity and movable link threshold value then.Corresponding at least being desirably between MS202 and communication system 200 foundation structures of this active link threshold kept the minimal communication number of links that can accept the operating in soft handover pattern.
When controller 212 determined that (418) communication link quantity or forward link quantity are lower than active link threshold, logical flow chart 400 proceeded to step 408.That is, when communication link or forward link quantity were lower than active link threshold, expectation was added new communication link 250 or forward link 252 to MS active communication link, and no matter reverse link circuit quality.Controller 212 determines that then (408) add in the Active Set of new BTS 209 and related communication link 250 to MS 202 thereof and do not carry out reverse link analysis.
When controller 212 determined that (418) communication link or forward link quantity are equal to or greater than active link threshold, logical flow chart 400 proceeded to step 402.That is, when communication link or forward link quantity were equal to or greater than active link threshold, expectation was added new communication link 250 or forward link 252 in the link with MS 202 active communications to, but is not very important.Controller 212 is carried out forward link analysis then, i.e. step 402, and 404,406, thus whether carry out reverse link analysis before determining in the Active Set that adds new BTS 209 and related communication link 250 to MS 202 thereof.
With reference now to Fig. 5,, shown the logical flow chart 500 of explanation controller 212 according to the method for embodiment of the invention execution reverse link analysis.When communication system 200, specifically to be controller 212 receive (502) communication systems from MS 202 adds BTS 209 to Active Set and/or when adding the request of communication link 250, logical flow chart 500 beginnings.Controller 212 is ordered the reverse link between (504) BTS 209 these BTS of decoding and the MS 202 then, and promptly reverse link 254.Respond this order, BTS 209, and processor 210 decodings (506) that specifically are BTS 209 are by the signal of reverse link 254 from MS 202 receptions.According to the signal of decoding, BTS 209, specifically are that processor 210 is determined (508) reverse link quality metric about decoded signal.BTS 209, specifically are that processor 210 compares the reverse link quality metric and the reverse link quality metric threshold value that is stored in the one or more storage arrangements 211 of BTS about reverse link 254 that (510) are determined then.Based on this relatively, BTS 209, specifically are processors 210, determine the signal whether (512) this BTS decodes acceptably and receive from MS 202 then, and with result notification controller 212.Based on the signal whether BTS 209 decodes acceptably and receive from MS 202, controller 212 determines then whether (514) add BTS 209 in the Active Set of MS 202 to.Logic flow 500 finishes.
In another embodiment, one or more steps 508 of logical flow chart 500,510,512 can be distributed in BTS 209 and the controller 212.For example, BTS 209 can measure the quality about reverse link 254, i.e. quality of signals about receiving by this reverse link, and transmit this and measure controller 212.This measurement can comprise reverse link quality metric, or controller 212 can be according to the definite reverse link quality metric about reverse link 254 of the measurement that receives.Then controller 212 relatively determine about the reverse link quality metric of reverse link 254 and be stored in reverse link quality metric threshold value in controller 212 one or more storage arrangements 216, to produce comparative result.According to this result, controller 212 determine BTS 209 whether can decode acceptably the signal that receives from MS 202 and, the signal according to whether this BTS can decode acceptably and receive from MS 202 determines whether to add in the Active Set of BTS 209 to MS 202.
For example, BTS 209 or controller 212 can be according to the predetermined number of frames about receiving by reverse link 254 of storage, 120 frames for example, or the one or more quality indicators about by the frame that receives in this reverse link predetermined time cycle of storage are determined reverse link quality metric.The frame of predetermined number or preset time cycle be so long as suitable, can be kept in one or more storage arrangements 211 of BTS or in one or more storage arrangements 216 of controller 212.When one or more quality indicators of storage comprise that this frame has been the indication of frame or delete frame, step 508 can comprise the quantity of being passed through to determine frame by BTS 209 or controller 212 based on the quality indicator of storage, for example the quantity of the delete frame that receives by reverse link 224 or the quantity of good frame are determined reverse link quality metric.Step 510 can comprise that the quantity of the frame of relatively being determined by BTS 209 or controller 212 and the threshold value that is stored in one or more storage arrangements 216 produce first comparative result then.
For example, determine the quantity of the delete frame that receives by reverse link 254 in step 508 when BTS 209 or controller 212, and when step 510 determined that further the quantity of determined delete frame has surpassed erased frame threshold, BTS 209 or controller 212 determined that reverse link 254 is not good link.Yet when if the quantity of the delete frame of determining surpasses erased frame threshold, BTS 209 or controller 212 determine that reverse links 254 are good links.By another example, determine the quantity of the good frame that receives by reverse link 254 in step 508 when BTS 209 or controller 212, and when step 510 further determined that determined good number of frames has surpassed good frame threshold value, BTS 209 or controller 212 determined that reverse links 254 are good links.Yet when if determined good number of frames has been no more than the frame threshold value, BTS 209 or controller 212 determine that reverse links 254 are not good links.
When communication system 200 determines not add new BTS in step 514, be BTS 209, and related communication link, be in the Active Set of communication link 250 to MS 202 time, BTS 209 and/or controller 212 can continue to consider BTS 209 and related communication link 250 thereof, and with it as adding the candidate, and initialization is added definite again.Fig. 6 be communication system 200 according to different embodiments of the invention after this BTS and communication link are not added in initial decision, determine whether to add the logical flow chart 600 of step of the activation concentrative implementation of BTS 209 and related communication link 250 to MS 202 thereof.When controller 212 is determined (602) not with BTS 209 and/or its related communication link, when promptly communication link 250 adds in the Active Set of MS 202, logical flow chart 600 beginnings.Determine not add after this BTS and/or the communication link, controller 212 is determined (604) and the current forward link quality metric that just is being in the soft handover with MS 202 and is retained in one of forward link 232,242 in the soft handover with MS in the incident that deletion BTS 206 and related communication link 220 thereof from Active Set, consideration are added the forward link 252 relevant with BTS 209 and related communication link 250 to this Active Set.Determine the cycle very first time when controller 212 reference timers 218 and arrive constantly that controller 212 is (606) forward link quality metric of determining and forward link quality metric threshold that is stored in controller 212 one or more storage arrangements 216 relatively.
When controller 212 determined that (608) these forward link quality metric and threshold ratio are more unfavorable, controller 212 determined that further (610) carry out soft handover and do not carry out reverse link analysis.That is, controller 212 adds in the Active Set of BTS 209 and related communication link 250 to MS 202 thereof and does not carry out reverse link analysis.When controller 212 determined that (608) forward link quality metric and forward link quality metric threshold are more favourable, controller 212 was further determined to carry out reverse link analysis before (612) are in determining whether to add the Active Set of BTS 209 and related communication link 250 to MS 202 thereof.Controller 212 determines according to reverse link analysis whether (614) add in the Active Set of BTS 209 and related communication link 250 to MS 202 thereof then.Logical flow chart 600 finishes.
In another embodiment of the present invention as shown in Figure 6, its middle controller 212 continues after determining not add BTS 209 and communication link 250 as interpolation candidate consideration, rather than when the drop/add request that does not receive subsequently, just determine whether to add BTS209 and communication link 250 subsequently, arrive constantly when second time cycle, controller 212 can transmit drop/add request by prompting (616) MS 202.Second time cycle is definite by controller 212 reference timers 218, can be identical or different with the cycle very first time.The expectation of drop/add request instruct MS is added or is not added in BTS 209 and communication link 250 to MS 202 Active Sets.Preferably, controller 212 is pointed out MS 202 drop/add request by transmitting pilot measurement request command (PMRO) to MS.
In response to receiving prompting, MS 202 transmission indicative of desired are added or are not added the drop/add request of the Active Set of BTS 209 and communication link 250 to MS 202 and give controller 212, and controller 212 receives (618) this request from MS.Preferably, this drop/add request is drawn together PSMM message, and MS embeds the indication of whether adding or not adding BTS and communication link therein.When the drop/add request indicative of desired is added BTS 209 and communication link 250, forward link quality metric threshold in forward link quality metric that controller 212 comparisons (620) are determined and the one or more storage arrangements 216 that are stored in controller 212, logical flow chart 600 proceeds to step 608.
In a word, for guaranteeing during soft handover, before deleting communication link 220, add in the Active Set of MS 202 having the BTS 209 that can accept quality reverse link 254, communication system 200 can be carried out the reverse link analysis of the reverse link 254 that will add.Yet, before carrying out reverse link analysis, communication system 200 determines that at first this communication system can stand any delay relevant with carrying out reverse link analysis, maybe when the expectation reverse link analysis, can stand and passes through the relevant delay of execution forward link analysis.When communication system 200 determined that communication system is impatient at the delay relevant with carrying out reverse link analysis and/or is not carried out reverse link analysis, communication system was added BTS 209 and related communication link 250 and 254, and does not carry out reverse link analysis.When communication system 200 determines that communication systems can be stood the delay relevant with carrying out reverse link analysis and/or when expecting reverse link analysis, communication system is carried out the analysis of reverse link 254, and, determine whether to add BTS 209 and the communication link relevant in the Active Set of MS 202 with this BTS according to reverse link analysis.When determining not add BTS209 in Active Set the time, communication system 200 is the relevant forward link of monitoring and MS 202 further, and determining whether rethinking interpolation BTS 209, and the communication link relevant with this BTS is in Active Set.
Though show and illustrated that the present invention, those skilled in the art are to be understood that and to make different changes and equivalence is replaced to its assembly with reference to specific embodiment, and do not deviate from the scope of being stated in below the claim.Therefore, specification and accompanying drawing should be considered to illustrate, but not limited significance, change that all are such and replacement all are included within the scope of the invention.
Benefit, other advantages have been described and to the solution of problem with reference to specific embodiment.Yet, can cause that any other benefit, advantage or scheme occur or clearer and more definite benefit, advantage or solution is not considered to arbitrarily or all authority requires key, necessary or necessary feature or key element.As used herein, the expectation term " comprises ", " comprising " or its any variation cover a kind of non-monopoly and comprise, the processing, method, parts or the equipment that for example comprise the element tabulation not only comprise these elements, also comprise other elements or the intrinsic element of these processing, method, parts or equipment clearly do not listed.Can further understand, if any, the use of any relational terms, for example first and second, top and bottom etc. only are used to distinguish an entity or action and another entity or action, rather than necessarily require or hint the relation or the order of any this reality between these entities or action.
Claims (10)
1. method of carrying out soft handover in wireless communication system comprises:
Receive to add the request of base station in the travelling carriage Active Set;
Determine whether to analyze the reverse link relevant with this base station;
When determining not analyze reverse link, add this base station in Active Set, and do not estimate reverse link;
When determining to analyze reverse link, estimate reverse link; And
When estimating reverse link,, determine whether to add this base station in Active Set according to this evaluation.
2. the method for claim 1 determines whether that wherein analyzing reverse link further comprises:
Determine the forward link quality metric of the forward link of corresponding at least one base station, this at least one base station is the Active Set member, and does not consider it is deleted from Active Set;
Compare forward link quality metric and forward link quality metric threshold, to produce comparative result; And
According to comparative result, determine whether to analyze with above-mentioned first base station and second base station in relevant reverse link one of at least, wherein this second base station is the member in the travelling carriage Active Set.
3. the method for claim 1 determines whether that wherein analyzing reverse link comprises:
Determine that current and travelling carriage carries out the quantity of the communication link of active communications;
Relatively this communication link quantity and active link threshold; And
When communication link quantity is lower than active link threshold, determine not analyze reverse link.
4. the method for claim 1 determines whether that wherein analyzing reverse link comprises:
Determine that current and travelling carriage carries out the quantity of the communication link of active communications;
Relatively this communication link quantity and active link threshold;
When communication link quantity is equal to or greater than active link threshold:
Determine the forward link quality metric of the forward link of corresponding at least one base station, this at least one base station is the Active Set member, and does not consider it is deleted from Active Set;
Relatively this forward link quality metric and forward link quality metric threshold are to produce comparative result; And
According to comparative result, determine whether to analyze with above-mentioned first base station and second base station in relevant reverse link one of at least, wherein this second base station is the member in the travelling carriage Active Set.
5. the method for claim 1, wherein this method further comprises, when determining not add first base station in Active Set the time:
Determine the new forward link quality metric of the forward link of corresponding at least one base station, this at least one base station is the Active Set member, and does not consider it is deleted from Active Set;
In response to the time cycle then, more above-mentioned new forward link quality metric and forward link quality metric threshold are to produce new comparative result; And
According to new comparative result, determine whether to analyze with above-mentioned first base station and second base station in relevant reverse link one of at least, wherein this second base station is the member in the travelling carriage Active Set.
6. in wireless infrastructure, a kind of equipment that is used to carry out soft handover, comprise processor, this processor determines whether to analyze the reverse link relevant with the base station, wherein considers this base station is joined in the Active Set of travelling carriage, when determining not analyze reverse link, this base station is added in the Active Set and do not estimate reverse link, when determining to analyze reverse link, estimate this reverse link, and when estimating this reverse link, determine whether this base station is added in the Active Set according to this evaluation.
7. equipment as claimed in claim 6, wherein said equipment further comprises at least one storage device, this storage device is connected to processor, be used to preserve forward link quality metric threshold, wherein said processor is following to determine whether to analyze reverse link: the forward link quality metric of determining the forward link of corresponding at least one base station, this at least one base station is the Active Set member and does not consider it is deleted from Active Set, relatively this forward link quality metric and forward link quality metric threshold to be producing comparative result, and the relevant reverse link in base station that determines whether to analyze and consider it is added Active Set according to comparative result.
8. equipment as claimed in claim 6, wherein said equipment further comprises at least one storage device, this storage device is connected to processor, be used to preserve active link threshold, and wherein said processor is following to determine whether to analyze reverse link: determine that current and travelling carriage carries out the quantity of the communication link of active communications, relatively this communication link quantity and active link threshold, and when described communication link quantity is lower than active link threshold, determine not analyze reverse link.
9. equipment as claimed in claim 6, wherein said equipment further comprises at least one storage device, this storage device is connected to processor, be used to preserve active link threshold, and, wherein said processor is following to determine whether to analyze reverse link: determine that current and travelling carriage carries out the quantity of the communication link of active communications, relatively this communication link quantity and active link threshold, when described communication link quantity is equal to or greater than active link threshold, determine the forward link quality metric of the forward link of corresponding at least one base station, this at least one base station is the Active Set member and does not consider it is deleted from Active Set, relatively this forward link quality metric and forward link quality metric threshold are to produce comparative result, and according to comparative result, determine whether to analyze with above-mentioned first base station and second base station in relevant reverse link one of at least, wherein this second base station is the member in the travelling carriage Active Set.
10. equipment as claimed in claim 6, when determining not add first base station in Active Set the time, wherein said processor is determined the new forward link quality metric of the forward link of corresponding at least one base station, this at least one base station is the Active Set member and does not consider it is deleted from Active Set, in response to the time cycle then, newer forward link quality metric and forward link quality metric threshold are to produce new comparative result, and according to new comparative result, determine whether to analyze with above-mentioned first base station and second base station in relevant reverse link one of at least, wherein this second base station is the member in the travelling carriage Active Set.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US48380703P | 2003-06-30 | 2003-06-30 | |
| US60/483,807 | 2003-06-30 | ||
| US10/864,831 | 2004-06-09 |
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| Publication Number | Publication Date |
|---|---|
| CN1817052A true CN1817052A (en) | 2006-08-09 |
| CN100508630C CN100508630C (en) | 2009-07-01 |
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| CNB2004800188301A Expired - Lifetime CN100508630C (en) | 2003-06-30 | 2004-06-24 | Method and apparatus for performing soft-handoff in a wireless communication system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101141686B (en) * | 2006-09-07 | 2010-08-18 | 株式会社Ntt都科摩 | Radio control method and radio control apparatus |
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2004
- 2004-06-24 CN CNB2004800188301A patent/CN100508630C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101141686B (en) * | 2006-09-07 | 2010-08-18 | 株式会社Ntt都科摩 | Radio control method and radio control apparatus |
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| CN100508630C (en) | 2009-07-01 |
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