CN101018407B

CN101018407B - Method and apparatus for call recovery in a wireless communication system

Info

Publication number: CN101018407B
Application number: CN2007100044781A
Authority: CN
Inventors: 陈道; 王俊
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2000-12-05
Filing date: 2001-11-29
Publication date: 2011-11-16
Anticipated expiration: 2021-11-29
Also published as: UA73813C2; CN101018407A; UA79233C2

Abstract

A method and apparatus for call recovery in a wireless communication system (10). When the communication link between a mobile station (38) and a base station (34) is in trouble, the mobile station and the infrastructure prearrange potential rescue base stations (34). The source cell base station contacts all recovery-capable neighbors as potential rescuers. Each rescue base station is instructed to use a default channel for rescue transmissions. The rescue transmission is considered a call recovery operation. The mobile station establishes a soft hand-off with rescue base station, wherein the FL uses the default channel and an alternate channel. Once hand-off is complete the rescue base station discontinues use of the default channel. In one embodiment, the source cell base station provides the mobile station with the list of recovery-capable neighbors as overhead during transmissions and prior to development of the communication link problem.

Description

The method and apparatus of call recovery in wireless telecommunication system

The application is to be application number the dividing an application for the Chinese patent application of " method and apparatus of call recovery in wireless telecommunication system " that be No. 01820014.1 denomination of invention on November 29 calendar year 2001 the applying date.

Technical field

The present invention relates to wireless speech and data communication, especially, the present invention relates to the novelty of call recovery in wireless telecommunication system and the method and apparatus of improvement.

Background technology

Wireless telecommunication system comprises a plurality of base stations (BS) usually, and each and little service area and/or sector are got in touch, and with a plurality of mobile radio stations (MS) communication.The base station is controlled by base station controller (BSC).When mobile radio station passes whole system when moving, fluctuation appears in the signal quality that receives from the base station.When the communication link between base station and given mobile radio station degenerates, might be by setting up the communication that prevent loss of link with at least one other base station.A switching (hand-off) process provides such generation of selecting communication link else.In switch instances, fabric and each base station and mobile radio station are consulted.But signal quality usually worsens too soon so that can not hold consultation.

Therefore, the method and apparatus that needs call recovery in various situations.In addition need be in wireless telecommunication system the reliable method of call recovery.

Summary of the invention

The embodiment that is disclosed is provided at the method for the novel and improvement of the conversation that recovers deterioration in the wireless telecommunication system.By an aspect, in having the wireless telecommunication system of a plurality of base stations, each of a plurality of base stations has the neighbour station group that comprises neighbor base station, and each neighbor base station has the passage of acquiescence, a kind of method comprises transmission default channel information to mobile radio station, detects the appearance that call recovery triggers; And order all base stations in the group of neighbour station send on silent approvement passage separately.

In one aspect, wireless device comprises antenna; Be connected in the processor of antenna; Be connected in the transmitting line of antenna and processor; Be connected in the receiving lines of antenna and processor; By executable first set of computer readable instructions of processor, be used to receive the neighbour station table of base station, this table comprises specifies the default channel at each adjacent station; By executable second set of computer readable instructions of processor, be used to discern the call recovery triggering and forbid transmitting line in response; With by executable the 3rd set of computer readable instructions of processor, be used to set up and the switching at least one adjacent station.

In another aspect, wireless device comprises transmitter circuit; The call recovery regulon, its operation after the call recovery operation is to produce the predetermined electric power control command; With the power adjustments unit that is connected call recovery regulon and transmitter circuit, this power adjustments cell response power control instruction operation is to regulate transmitter circuit.

In aspect another, computer program is embedded into the computer-readable medium that comprises computer executable instructions.Wherein this program comprises that operation discerns first group of instruction of special event; Forbid second group of instruction of call recovery in the special event manipulate; Notify the three group instruction of wireless telecommunication system with operation about special event.

Description of drawings

The detailed description of listing below in conjunction with the drawings, the feature of the present method and apparatus that discloses, target and advantage become apparent, the object that similar reference character correspondence is equal in institute's drawings attached, wherein:

Fig. 1 illustrates wireless telecommunication system by an embodiment with the block diagram form;

Fig. 2 illustrates a part by the wireless telecommunication system of an embodiment such as Fig. 1 with the block diagram form;

Fig. 3 illustrates two signal of base station quality in as the wireless system of Fig. 2 by an embodiment in the mode of time diagram;

Fig. 4 illustrates by an embodiment during restoration as the part of the wireless telecommunication system of Fig. 1 in the block diagram mode;

Fig. 5 illustrates two signal of base station quality in wireless telecommunication system by an embodiment with the form of time diagram;

Fig. 6 A and 6B illustrate the method at a base station call recovery by an embodiment in a flowchart;

Fig. 7 A and 7B illustrate the method at the mobile radio station call recovery by an embodiment in a flowchart;

Fig. 8 illustrates layer of structure by the system of an embodiment such as Fig. 1 with the block diagram form;

Fig. 9 illustrates call recovery operation by the system of an embodiment such as Fig. 1 with the form of time diagram;

Figure 10 illustrates the initialization at mobile radio station transmitted power energy level after call recovery by this a embodiment with the form of time diagram;

Figure 11 is illustrated in the operation of wireless device in the system of Fig. 1 in a flowchart.

Embodiment

Provide relevant information of being close to little service area and/or sector by embodiment method of call recovery in wireless system, those zones can be used for, and can do communication to the mobile radio station that the potential hazard of losing communication link is arranged and recover.Each has the base station of call recovery ability to have the forward call recovery passage of the acquiescence of being discerned by predetermined codes.In other embodiment, specify more than an acquiescence forward call recovery passage each adjacent area, and the mobile radio station use has IMSI (international mobile station sign), TIMSI (interim international mobile station sign), ESN (Electronic Serial Number), system clock, or the hash function of its combination receive transmission so that determine to use which passage to receive from the base station of each energy call recovery fatefully.Mobile radio station can use that passage from the call recovery base station received signal then.When mobile radio station visit base station, control subchannel from a plurality of contiguous call recoveries base station by this mobile radio station combined power of extra information order.Even mobile radio station is not having the idle condition of continuous communication link, when mobile radio station moves into the footprint of base station,, or organizing when mobile radio station changed switch instances this also can take place when movable by the communication channel message that takes place in conversation.

Fig. 1 illustrates the wireless telecommunication system 10 with a plurality of

little service areas

12,14,16,18,20,22,24.

Little service area

12,14,16,18,20,22,24 is by radio broadcasting interface and BSC26 communication.Each

little service area

12,14,16,18,20,22,24 has corresponding adjacent area group, is made up of the little service area in the territory on the geography and/or in the proximity in the transmission.For example little service area 18 has and comprises

little service area

12,14,16,20, in 22,24 the adjacent area.At spread spectrum transmission system, as being called " the TIA/EIA/IS-95Mobile Station-Base Station CompatibitityStandard for Dual-MODE Wideband Spread Spectrum Cellular System " of " IS-95 standard " after thus, or be called the TIA/EIA/IS-2000Standard for cdma2000SpreadSpectrum System of " cdma2000 standard " thus " in code division multiplexing (CDMA) system of regulation; spread spectrum signal occupies same bandwidth chahnel, and wherein each signal has its own independent pseudo noise (PN) sequence.Operating in the following United States Patent (USP) of cdma system described: sequence number 4,901,397, be entitled as " SPREADSPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USINGSATELLITE OR TERRESTRIAL REPEATERS, " and sequence number 5,103,459, be entitled as " SYSTEM AND METHOD FOR GENERATING WAVEFORMS IN A CDMACELLULAR TELEPHONE SYSTEM ", both give the agent of present patent application, and directly add as a reference.In this way, a plurality of users send message simultaneously on same bandwidth chahnel.

Fig. 2 illustrates the part of the system 10 of Fig. 1, comprises being labeled as BS1, with the base station 32 of MS38 communication.BS132 is in the little service area 18 of Fig. 1.

Other base station

34,36 that is labeled as BS2 and BS3 respectively is respectively in little service area 16,24.The radio broadcasting interface be used for from the forward link (FL) of BS1 32 to MS38 and from MS38 to BS1 32 reverse link (RL) media is provided.Notice that MS38 can move in system 10, feasible from the reciprocal signal quality deteriorates of BS1 32.In order to begin conversation, MS38 sends transmission information on access path.BS1 32, and BS2 34 and BS3 36 send the passage specify message on the call passage.Passage is specified each identification of base stations Walsh sign indicating number index.

Signal quality is measured with signal to noise ratio (snr) usually, and can be expressed as the ratio (Ec/Io) of every chip pilot energy and the overall power density of reception.Fig. 3 is illustrated in the figure of MS38 to the signal quality of BS1 32 and BS2 34 measurements.The signal quality of BS2 34 is begun to increase and surpass in the continuation increase of t1 place the threshold value of following T_ADD mark at the time t0 place.Threshold value T_ADD provides the signal quality of reference, surpasses it, and order MS38 informing base station increases a base station in its activity group (AS).AS is made up of those base stations.They send and receive communication versatilely with MS38.AS chooses from the base station of candidate set (CS) usually.CS comprises that reserve becomes the base station with MS38 activity communication.CS is base station selected from neighbour station group (NS) usually.

Continuation is with reference to figure 3, and when the signal quality of BS2 34 improved, the signal quality of BS1 32 had degenerated.Because to given signal of base station be the signal energy of coming from that base station other the comparison of the energy of signal occurs to all, the energy level increase of the signal that receives from BS2 34 is added to from the signal degradation of BS1 32.At time t1, the signal energy that MS38 records BS2 34 surpasses T_ADD.This points out to MS38, needs suitable action, promptly triggers and switches.At time t2, MS38 sends the Pilot Strength Measurement Message (PSMM) that comprises the metrical information of BS1 32 and BS2 34 to BS1 32 and BSC26.At time t3, BSC26 is to the link of MS38 foundation from BSC26 to BS234.BSC26 comprises a selector.BSC26 sets up a communication link, forms about MS38 at BS132 " oppositely " communication network between BS2 34 and the BSC26.At time t4, BS1 32 send comprise identification BS132 and BS2 34 and to come from BS1 32 and BS2 34 the hand off direction message (HDM) of the relevant sign indicating number index of forward link (TL) passage.This information MS38 can be received and demodulation from BS1 32 and BS2 34 come signal.Receive HDM at time 5MS38, and the beginning demodulation is added to from the signal of BS1 32 from the signal of BS2 34 from BS1 32.Note, in this example, have only a new base station to relate to switching.But, can there be the base station of any number to be involved in such switch instances, wherein those base stations with the MS38 communication form an AS.When MS38 receives from a plurality of base stations among AS when comprising the signal of symbol, MS38 can make up these signals and form stronger signal.This anabolic process be referred to as FL's " soft combination ", and use according to the weighting of signal quality and finish with the best proportion compound mode.At time t6, MS38 sends the affirmation to the HDM that receives from BS1 32, or points out to complete successfully the handoff completion message (HCM) of switching.

Refer again to Fig. 3, may cause the too fast situation of signal quality increase of BS2 34.In this situation, with respect to BS1 32, the signal strength signal intensity of BS2 34 is encouraged the deterioration of BS1 34 signal qualitys.Receive to switch necessary information (as the necessary pseudo noise of passage (PN) biasing of using for

identification BS2

34 or 34 couples of MS38 of BS2) before MS38 can not with the fabric communication.

In common CDMA handoff procedure, when mobile radio station when the footprint of a base station moves on to the footprint of another base station, switch and avoided losing of communication link.In the class as soft handover was switched, mobile radio station kept and being connected of two or more base stations simultaneously.The current location of mobile radio station can be thought the little service area in source, and the next little service area that mobile radio station is shifted to can be called the little service area of target.A plurality of signals that mobile radio station uses the receiver of search-type to come demodulation to receive on the FL of a plurality of base stations.Two signals are combined, and form to have the composite signal that improves quality.Though be involved in the signal that each demodulation of a plurality of base stations of soft handover receives respectively, each sends the information of demodulation sign indicating number and gives BSC.BSC comprises the selector of selecting best frame from a plurality of received frames.The switching of type can be used for the demand of various situations and system in addition.

In the auxiliary switching (Mobite-Assisted Hand-Off-MAHO) of mobile radio station, mobile radio station is made signal quality measured to the FL pilot signal of coming from a plurality of mobile radio stations.This report information is to source base station.Signal quality and a plurality of threshold ratio increase the base station to the AS decision to make.If the signal quality of given pilot tone is greater than pilot detection threshold value T_ADD, then this pilot tone is added to AS.In other embodiment, pilot tone at first is added to CS, is added to AS then.In fact, the threshold value state of being convenient to the base station is delivered to another group from one group.

In the impossible situation of handover negotiation optimization, call recovery provides information to mobile radio station in advance.Call recovery starts in all cases.When normal operation, mobile radio station and base station are used to trigger and are determined the operation that they are suitable.For example, the mobile radio station of running uses a plurality of threshold values to make about repay the decision of what information to the base station in system 10.A threshold value T_ADD points out the signal quality grade as discussed above, is used for the base station is added to AS.When mobile radio station receives the signal that measured value is higher than T_ADD, mobile radio station moves into CS with this base station, searches for that base station more continually, and by existing AS to this state of System Reports.Other threshold value T_DROP provides a signal quality level, will give up from AS if be lower than this grade base station.When move receiving a signal, its measured value be longer than T_TDROP during be lower than T_DROP, mobile radio station by existing AS to this situation of System Reports.Every kind of situation, this information of base station relaying in AS is to base station controller.

For call recovery, various any that may trigger are sought in the base station in AS.When the FL signal quality was lower than threshold value and is longer than another threshold time, the call recovery that the first kind takes place triggered.This type of triggering comprise when the base station when mobile radio station receives continuous power control (PC) request, be increased in the transmission energy level of this base station.Usually, the base station always sends to mobile radio station with the maximum energy level that binds.For example, the FL traffic is transmitted in predetermined time period and remains on high level.Mobile radio station can send the request of many increase power, i.e. UP order.In addition, mobile radio station can be reported many erasures (erasure) situation.Erasure when not having the confidence level of desired value more than the threshold level of one position, takes place in reception.In other situation, mobile radio station sends message, points out to the base station, and its outer ring set point is high or in the highest permissions grade, or in the oversize time of that grade process.

When certain response is arranged from mobile radio station expectation, but do not receive or receive different responses, second class then takes place trigger.This type of triggering comprises and lacks affirmation from mobile radio station to sent message that needs confirm by the base station.This message can be retransmitted pre-determined number before satisfying trigger condition.This predetermined number can be fix or variable, and can change by broadcasting.Equally, the base station may receive the repetition RL message that needs affirmation from mobile radio station, wherein receives this message after the base station sends affirmation.

The 3rd class triggers and relates to the low quality reverse link, when surpassing threshold level as the frame error ratio (FER) as RL.In addition, RL can keep high level in the given time.There is a situation can have high RL set point.The base station that is added to AS also has the call recovery that starts the recovery action and triggers.Most important triggering is from the BSC notice, has potential problem at given mobile radio station.In such situation, the base station begins from the mobile radio station search signal.

Mobile radio station also can use various call recoveries to trigger and enter call recovery.When improper number wrong arranged in the signal that receives the first kind taking place triggers.For example, may surpass predetermined threshold value at the FL of moving window erasure.In one embodiment, the threshold value limit is that 12 successive frames stand erasure.In this situation, mobile radio station will be turned off the transmitter part of mobile radio station, and open transmitter again when at least two FL successive frames do not have erasure.

When mobile radio station receives the PC order from the base station, when increasing power, order takes place the second class call recovery of mobile radio station is triggered.Because come big path loss from mobile radio station, the base station may have difficulty and receive the RL signal.

Need not be identified from the RL message of the affirmation of base station when one or more, the 3rd class takes place recover to trigger.This is called the repeating transmission retry trigger.Unsuitable response or not response may be arranged from the base station the message from mobile radio station similarly.After in fact mobile radio station sends affirmation if receive the FL message of the repetition that needs affirmation, the triggering of similar type takes place.

The 4th class call recovery takes place when mobile radio station sends predetermined time interval under high level to be triggered.In this situation, think that RL be not with enough energy to pass through to the base station.

In one embodiment, one or more utilizations that various call recoveries are triggered threshold value flexibly.Call recovery triggers and can attempt according to each transmission in system 10.Usually make these trials in the link layer between signalling and physical link.Link layer is called layer 2.Below with reference to Fig. 8 discussion.In the system of energy call recovery as the system 10 of Fig. 1, when the communication link as FL degenerated, MS38 finished the call recovery process to keep conversation.One is triggered normal starting recovery operation, wherein triggers and when represents parameter or measured value passing threshold.These threshold values can be dynamic, the conditions and environment of adaptive system 10.Similarly, threshold value can be regulated according to the history or the statistic record of the operation of system 10.

In one embodiment, on RL, repeat the number of times that sends, the time between continuous erasure, or the MS38 transmitter forbid it can being the response of order that the fabric from the system as BS1 32 and/or BSC26 10 is sent.In yet another embodiment, the state of mobile radio station and/or position provide triggering.The current transmission energy level of MS38 can trigger call recovery near predetermined maximum value.Triggering in addition comprises the quality of the FL that is measured by the erasure that transmits in current AS, not enough in the control of home loop power, and wherein the desirable SNR of MS38 is different from by home loop provides, etc.Embodiment can make up special parameter and mobile radio station situation as triggering in addition.

The fabric of system 10 can be MS38 and provides the class of operation information that helps determine the call recovery threshold value, and is selecting to use such information when MS38 provides preset parameter as activation threshold value.In one embodiment, be to running into the common number of times of trouble or cut conversation retry.Embodiment uses the input of RL to be provided with and to regulate threshold value in addition.Another embodiment can use the position of MS38 in system 10, as the area of given little service area.Another embodiment cooperates the date considered weekly and/or the time of every day with known mobile radio station traffic distribution apperance.In the place that can use and need, the combination of any of these mechanism also is attainable.

In the system 10 of Fig. 1 and 2, the additional information of each

base station

32,34,36 comprises the neighbour station table of its correspondence.Pseudo noise (PN) the sign indicating number skew of the correspondence at the adjacent station of table identification, adjacent station.

With reference to Fig. 4, by setting up the reverse link of BS1 32 and BS2 34, BSC26 responds any of various triggerings.By an embodiment, call recovery method 100 is started as shown in Figure 6.The specific signal quality figure of an example shown in Figure 5.Sometimes think that in this example MS38 has potential problems.

In the call recovery method 100 of an embodiment shown in Fig. 6 A and the 6B, in step 102, BS132 specifies the passage that the neighbor base station group of MS38 is sent acquiescence.Base station in the group of neighbour station be can call recovery the unit, have necessary software and/or hardware and realize call recovery, and have the footprint in the zone of the topped base station of sending adjacent station group.Default channel is specified the channel code index of identification by the acquiescence of the use of the base station in the group of neighbour station, comprises the sign indicating number to BS2 34.Each base station in the neighbour station group of energy call recovery has the acquiescence extended code that is used for identification mobile radio station when needing call recovery.The extended code of an embodiment is specific Walsh sign indicating number.In step 104, BS2 34 sends to retransmit and send retry trigger to give MS38.Repeating transmission send retry trigger to be limited to the number of retries of the MS38 that allows before the operation of starting call recovery.Judging diamond step 106 then, BS1 32 judges whether to occur call recovery and triggers.If do not occur recovering to trigger, processing procedure is waited until the appearance of triggering.When triggering occurred, process proceeded to step 108, ordered all base stations in the NS of BS1 32 to send on the corresponding default channel of corresponding MS38.Notice that communication link may can not be set up owing to the weakness of FL or RL in some base station in NS, but each base station in NS begins to send to MS38.The multiple MS38 of being sent in provides stronger FL signal and arrives the more reliable RL of BSC26.

Note, press present embodiment, the number of retries of RL message, or the time quantum that allows between the continuous erasure determined by BSC26, and offer MS38 through the message of special use and the radio link of broadcasting.Embodiment uses the preset parameter that is different from other parameter in addition.An embodiment adds the function of mobile radio station situation.The mobile radio station situation can be thought and how approaching the maximum actual transmission energy level that sends energy level comparison MS38 is.Similarly, other mobile radio station situation is considered the quality of FL, as the erasure on current AS.Another mobile radio station situation is considered the shortcoming of home loop.The shortcoming of home loop is poor between target ANR and the SNR that transmitted by home loop PC.Another embodiment is with the type combination of mobile radio station state and transmission.

The number of retries that allows can be cut off the statistics adjusting of conversation or problematic conversation according to relevant fault.For example, the average of retry can be arranged, surpass this number, most of problematic conversations can not recover.Consideration in addition comprises RL input, the position of MS38, and/or the time of every day, or date.Situation after, the amount of information distribution situation influence of some mobile radio station needs the number of the mobile radio station of quick conversation recovery.

Continue Fig. 6 A, in step 110, BSC26 determines the current AS of MS.In step 112, BSC 26 starts the HDM timers and sends HDM in step 114 then.In this point, system 10 wishes to love and respect you and removes default channel with communication link and can be used by any mobile radio station in the system 10, thereby uses and can optimize.Utilize given default channel simultaneously at MS38, this passage can not be used by other mobile radio station.The transmission that walks abreast with transmission in default channel start in order each base station among the NS on other or new passage.This is the starting of switch instances.

If judging that diamond 118 BSC26 of place receive message from MS38, point out to switch and finish, process proceeds to step 120, stops the communication link of member on default channel of MS38 and NS.Process proceeds to step 124 subsequently.On the contrary, if do not receive handoff completion message, judging diamond 122BSC26 verification, whether the HDM timer is covered.If the HDM timer is covered, suitable default channel is terminated to the transmission of MS38, at step 124 cancellation call recovery, and in step 125 termination use default channel and new tunnel.In step 126 enabling.If do not cover at judgement diamond 122 place's timers, process turns back at decision block diamond 118 and waits for the next handoff completion message from MS38.

Fig. 6 B refinement the part of method 100, wherein step 110 is illustrated as at step 130 initialization timing device.At the PSMM that judges that diamond 132BSC26 verification comes from MS38.If PSMM receives that process proceeds to step 134, AS is set makes the neighbour station that is included among the PSMM.Do not proceed to judgement diamond 138 if receive PSMM, process, judge whether timer (in step 130 initialization) is covered.If timer is covered, process proceeds to judges diamond 144.If timer is not covered, process proceeds to judges diamond 144.If timer is not covered, process turns back to judges diamond 132.

Set after the AS in step 134, be enhanced if judge diamond judgement RL, judging diamond 140, BSC26 judges whether the signal of any adjacent station acquisition MS38 among any PSMM of being not included in is arranged.These adjacent stations are called audible adjacent station (Hearing Neigbor-HN), and are added among the AS in step 142.Process turns back to the step 112 of Fig. 6 A then.

Do not receive PSMM if timer is covered, judging that diamond 144BSC26 judges whether that any adjacent area obtains RLMS38 signal, i.e. HN.In this situation, in step 146, AS is configured to comprise these HN.If, then recover, and termination of a call in step 148 finished call judging that diamond 144 does not find HN.

Judging diamond 110, method judges whether the transmitter of MS 38 closes.If transmitter cuts out, then in step 110, BSC26 order MS38 opens transmitter.

The mobile radio station call recovery method 200 of an embodiment shown in Figure 7.In step 202, the base station communication among MS38 and the AS (0).This just discerns current AS.If judging that diamond 204 call recovery occurs and triggers, process proceeds to judges diamond 208.It may be triggering discussed above that call recovery triggers, or other indication, points out that MS38 need save operation, and promptly MS38 may lose the FL communication link.If do not occur triggering, in step 206 beginning normal running.Judge that diamond 208 judges whether the transmitter of MS38 enables.If transmitter enables, process proceeds to step 214, and if not enable, MS38 judging diamond 210 verification trigger conditions.If trigger condition exists, point out that MS38 has forbidden transmitter, then take suitably action and process proceeds to step 214 in step 212.If triggerless points out that transmitter is under an embargo, then process proceeds to step 214.In step 214 waiting timer is set.Judging diamond 216 verification waiting timers, when covering, recovering timer in step 218 starting.If waiting timer do not cover, then process continues, and is judging that diamond 222 judges whether MS 38 gets back to normal mode of operation.Normal running continues from step 206, and else process turns back to wait state, and waiting timer is covered.

Continue Fig. 7, from step 218, if the transmitter of MS38 is under an embargo, at this sender-initiate of step 220.MS38 sends predetermined preamble duration cycle Y.The information that preamble provides relevant MS38 to send, rather than real data or symbol.In step 228, MS38 sends PSMM information.Judging diamond 228, if receive HDM or if receive the confirmation certain confirmation signal of PSMM, MS38 waits for predetermined period of time Y, upgrades AS after this.Whether if do not receive HDM or PSMM confirmation signal at judgement diamond 230, process proceeds to judges diamond 232, ought not send than maximum with verification PSMM to allow more times number of number of times.If PSMM can resend, promptly maximum ought not reach, and process turns back to step 228 and retransmits PSMM.But, if the maximum of receiving, then process proceeds to step 236, and call recovery stops.

Press the other method of call recovery, BSC26 notice have the BS1 32 of potential problems all can call recovery the neighbour station.BSC order MS38 opens the transmitter part of MS38 and orders the base station in the group of adjacent station to listen to MS38.In detection or behind the MS38 picked up signal, each base station in the group of neighbour station sends a report.This report receives that from the subclass of base station wherein this subclass can comprise all base stations or part base station in this neighbour station group.The default channel of BSC26 notice MS38 each base station in this subclass.Suitable default channel starting and the communication of MS38 are used in the base station of this subclass then.

In yet another embodiment, the subclass of adjacent station group is according to the PSMM decision that sends recently.Have a problem, recently the PSMM that sends may correctly not received, and in this situation, the PSMM that is used to discern this subclass is incorrect.For example, when PSMM identification BS1 32 that receives recently and BS3 36, MS38 sends the PSMM of an identification BS1 32 and BS2 34, and it is not received, and call recovery is hindered.The connect reverse network of BS3 36 of BSC26, and BS3 36 beginnings begin the transmission to MS38 on the silent approvement passage.Unfortunately, it is to set up communication with BS2 34 that MS38 thinks to call recovery, and prepares to receive on different default channel.From being wasted of BS3 36, and more noises in fact in system 10, have been caused more than transmission.

When call recovery is started by MS38, can use timer to postpone such starting after all call recoveries occurring.The time cycle of timer can be provided with by BSC26.After timer was covered, MS38 sent preamble on the RL pilot channel.This preamble comprises call recovery message.In one embodiment, preamble is can be by the constant of BSC26 setting.In other embodiment, preamble is the variable-length signal of being determined by the Systems Operator.After sending preamble, MS38 sends the message that relevant FL changes.This message can be PSMM.This message can send for several times and be received by BS2 34 with assurance.

The combination of above-mentioned all methods provides the various advantages of call recovery.In one embodiment, the call recovery method is the radio transmitting environment according to little service area base station, source.Number when neighbour station that can call recovery is little (as 2), and BSC26 will order all neighbours to stand on separately the default channel and send.AS is updated and the transmitter of MS38 is enabled and not delay.To the neighbour station group of big energy call recovery, the signal that BSC26 will order all adjacent stations to be listened to from MS38.After the delay that causes waiting for their signals of whether receiving of adjacent station report, order those to hear that adjacent station uses the passage of acquiescence from MS38.Similarly, if receive PSMM from MS38 in the cycle, order those base stations to use the passage of acquiescence by PSMM identification at preset time.Notice that when FL is correct running, (this can be determined by the continuous good frame of fixed number) thought effectively through the PC order that the PC subchannel sends.

Fig. 8 illustrates the structure of the wireless telecommunication system 10 of Fig. 1 with the hierarchical structure form.Structure 700 comprises three layers: signals layer 702; Link layer 704; With physical layer 706.Signals layer 702 provides the signalling 708 on upper strata, data, services 710; With voice service 712.Signals layer 702 provides voice, bag data, simple track data and synchronous voice and bag data, services.This layer on corresponding to beneath two-layer provide agreement and service.Link layer 704 is divided into link access control (LAC) sublayer 714 and medium access control (MAC) sublayer 716 again.The agreement of the application and the layer 712 that signals is provided by the service that is provided by LAC sublayer 714.Link layer 704 as the upper-layer protocol of the layer 702 that signals and and application and physical layer 706 between interface.Media access control sublayer 716 also comprises multiplexed and service quality (QOS) is submitted piece 722 to.Link layer 704 connects signals layer 702 to physical layer 706.Physical layer 706 is formed the physical channel 724 that sends.

Fig. 9 provides the sequential situation by the operation of the system 10 of an embodiment Fig. 1.To Fig. 6 A, 6B and 7 method are made reference.The trunnion axis express time, and vertical axis is represented each passage of being used to transmit.Provide the source little service area base station BS 1 32 in the centre, wherein signal sends to MS38 through communication channel.MS38 is illustrated two passages: sendaisle Tx; With receive path Rx.To finishing passage: Rx1 and Rx2 two situations are shown.Base station, one adjacent station also is shown, and it is target BS BS234.Default channel and new tunnel are shown.New tunnel is the passage that is used for after switching with the MS38 communication.Process receives from the transmission of an AS who is identified as AS (0) from MS38.MS38 sends on the communication channel of the little service area BS1 32 to the source simultaneously.At time t1, call recovery takes place trigger.MS38 and BS1 32 all distinguish this triggering.Noticing that triggering can be a common event, as for 32 the PC that the continues request from MS38 to BS1 of the transmitted power that increases FL, perhaps can be to MS38 and 32 fens other incidents of BS1.And MS38 and BS132 can not distinguish this triggering at the same time.Before BS1 32, distinguish triggering at MS38 between the FL age at failure.

When triggering in time t1 identification, the BSC26 starting sends from the stand default channel of BS2 34 of neighbour.At time t2, BS2 34 beginnings send to MS38 in default channel.This transmission is parallel with the same transmission from BS1 32.When occurring triggering, MS38 forbids transmitter at the scheduled wait time durations.At time t3, the stand-by period stops, and MS38 sends preamble duration cycle Y.Simultaneously, the AS of MS38 changes to AS (1) from AS (0).In AS (1) identification the base station be nearest PSMM list all base stations.In other embodiment, AS (1) can be all adjacent station and BS132 itself of BS1 32.

At time t4, preamble finishes, and MS28 begins to send current PSMM.Response sends HDM in the reception of time t5PSMM at time t6BS1 32 and BS2 34.At time t8, HDM signalisation AS changes to AS (2).Notice that next PSMM sends at time t7, wherein PSMM is sent periodically or continuously, to be identified in the signal that MS38 receives.

At time t8, BS2 34 beginnings send MS38 on new passage.MS38 sends HCM, and it triggers end transmission to MS38 on default channel at time t9.In one embodiment, HCM is sent periodically or continuously, is confirmed by the base station up to its correct reception.In the situation shown in Fig. 9, call recovery begins and stops at time t9 at time t2.At time t9, switching is finished, and BS2 34 is the little service area base stations, current source to MS38.

Receive path Rx2 is illustrated other situation.Here AS (0) maintenance activity before time t5.After the time t5, MS38 continues after this to change to AS (1) from AS (0) reception information in the predetermined time cycle X.This has just considered extra time to base station side, so as BS132 can call recovery the subclass at neighbour station on determine for the transmission of call recovery to MS38.At time t8, response HDM has the change subsequently from AS (1) to AS (2).This situation wherein has only and can be ordered the default channel through separately to send from those adjacent stations of MS38 picked up signal corresponding to such method.

In case finishing that and switch, call recovery realizes that MS38 must determine the initial transmission power energy level.By an embodiment.The system 10 of Fig. 1 uses closed power to control and regulates the transmitted power energy level.The embodiment of alternative can use other open-loop power control method.Open loop relates to the operation of transmitter (no matter being mobile radio station or base station)-control, does not wherein directly comprise receiver.For example, specific reverse link open Loop Power control requires mobile radio station to regulate reverse link transmit power according to the power levels of the signal that receives from the base station through forward link.The operation of closed power control expanding open loop, thus receiver participates in making the decision of power adjustments on one's own initiative.For example, to RL closed power control, the power levels of the signal that the base station will receive from given mobile radio station and threshold ratio are.The base station according to this relatively orders mobile radio station to increase or the minimizing reverse link transmit power then.On the contrary, the power levels of the signal that mobile station monitors receives on FL, and the base station that feeds back to about the quality of FL is provided.Close loop maneuver is used to compensate the power fluctuation relevant with the decay of given link as Raleigh decays.

Before just covering the stand-by period and setting up power control, MS38 begins to send with the initial power energy level.RL transmitted power energy level can recover before the transmitter of just forbidding MS38.Power levels can remain on this initial level, recovers up to closed power control.

In the embodiment of alternative, power levels is initialised to the final energy level of forbidding that transmitter is preceding, and increases gradually with predetermined speed subsequently, recovers up to function control.The speed that increases is provided with by BS1 32 and/or BS2 34 usually, and but fixed value or variable.This increase lasts till that the control of RL closed power recovers.

Embodiment begins call recovery according to received power total in the frequency band with open loop control in addition.This process is similar to the access procedure that defines in IS-95 and IS-2000.This can proofread and correct the visible forward link of MS38 base station a plurality of.Open loop control lasts till that always closed-loop control recovers.Figure 10 illustrates the power adjustments by this embodiment.Trunnion axis express time and vertical axis is represented the transmitted power energy level.At very first time t1, transmitted power is the initial power energy level.Time t2 after the cycle very first time, transmitted power increases predetermined increment size.Increment size can be a fixed value, can be variable, increases in time or reduces.In one embodiment, increment size is adaptive and the situation of responding system 10, and wherein increment size can increase or reduce from a time cycle to the next time cycle.At last, after the time cycle of predetermined number, can reach predetermined maximum transmit power energy level.Transmitted power reaches and binds then, the control of Wait-to-Restore closed power.

In yet another embodiment, initial transmission power is according to the pilot signal quality that receives.AS signal quality to expectation is measured with pilot tone Ec/Io or pilot tone Ec.In open loop control, transmitted power has following relation usually:

T _x＝(-R _x)+k(1)

Wherein k is a constant, and Tx is that RL sends energy, and Rx is the energy that FL receives.To close-loop power controlling method, transmitted power has following relation usually:

T _x＝(-R _x)+k+y(t)(2)

And y (t) is the correcting variable according to all effective power control command accumulative totals of receiving till time t.Item (k+y (t)) is called β.In another way, following relation is arranged:

T _x+R _x＝k+y(t)(3)

The β that will send in the past when determining initial transmission power is applied to new transmission.The new then following calculating of transmitted power energy level:

T _x(t)＝(-R _x(t)+T _x(0)+R _x(0)，(4)

T wherein _x(0) is the preceding transmission energy of call recovery, R _x(0) is received energy before call recovery.With the method, transmitted power is pressed the transmitted power energy level to receiving power levels rate regulation in the past.

At the wireless device MS38 that as mobile phone or PDA(Personal Digital Assistant), operates in the system 10 at Fig. 1 Figure 11 illustrating.This MS38 comprises and is used to the antenna 300 that sends and receive.Antenna 300 is connected to antenna multicoupler 302, is used for receiver path and transmitter path are isolated.Antenna multicoupler is connected to receiver circuit 308, forms receiver path, and is connected to amplifier 304 and transmitting line 306, forms transmit path.Amplifier 304 is also connected to the power adjustments unit 310 of the control that amplifier 304 is provided.Amplifier 304 receives from transmitting line 306 and sends signal.

Supply with the power control unit 314 of realizing the closed power controlling schemes through the signal that antenna 300 receives.Power control unit 314 is connected to communication bus 318.Communication bus 318 is provided at the public connection between each module among the MS38.Communication bus 318 is also connected to memory 322 and call recovery regulon 316.Memory 322 storages can be used for the various operations of MS38 and the computer-readable instruction of function.Processor 320 is carried out the instruction that is stored in memory 322.To normal mode of operation, power control unit produces the PC signal, delivers to power adjustments 310 through multiplexer 312.Power adjustments 310 is sent to amplifier 304 with the PC signal as amplifying stage then.

When call recovery took place, MS38 can forbid transmitter.When transmitter enabled again, handoff completion signal offered call recovery regulon 316.Handoff completion signal order call recovery regulon 316 produces predetermined PC signal.The PC signal that produces like that can be realized any scheme that above-mentioned Initial R L transmitted power produces.Maybe can realize the method selected else.Handoff completion signal also provides controls multiplexer 312.After call recovery, enter the power adjustments unit by the PC signal that recovers regulon 316 generations.Begin closed power control simultaneously.In case recovery is finished in closed power control, the switching signal cancellation, the PC signal that multiplexer 312 is selected by power control unit 314 generations is to provide power adjustments 310.The operation of call recovery regulon 316 can be by finishing by software instruction microprocessor operating 320, or realize with hardware for running effectively reliably.

In one embodiment, the specific operation of MS38 or BS1 32 is thought special incident.Special incident comprises various conditions and the process that makes a mistake and trigger that cause.In other words, special incident can produce the situation that call recovery triggers that takes place, but conversation does not degenerate.A special incident is the search of mobile radio station locator.Order MS38 searches on the other frequency that is used for global positioning system (GPS) signal.GPS provides the partial information of the position of the position of MS38 or MS38.Carry out to shift position locator search cycle ground or aperiodic.Usually, MS38 has the prior information of searching for sequential about such.Incident can be included in the candidate frequency search (CFS) of preparing in the inter-frequency hard handoffs in addition, wherein mobile radio station be tuned to frequency in addition, the signal that comes with search base station on different frequency.

Incident can be included in and trigger the action of being taked by MS38 during being left in the basket in addition.In these types of events, MS38 is to the BS1 of the little service area in source 32 notice special events.In one embodiment, special incident is a candidate frequency search (CFS), wherein MS38 be tuned to different frequency to seek on that frequency the signal that the base station comes of standing from the neighbour.This allows the transfer between the different frequency footprint, as at person communication system PCS) switching between frequency and honeycomb (cellular) frequency.When the special incident of this type of mobile radio station starting takes place, MS38 the special time cycle or next time before the notice the little service area BS1 32 of notification source ignore triggering about MS38.

By an embodiment, in order during special incident, to avoid such erroneous trigger, allow this incident as little service area base station, the source of BS1 32, and the sequential of this incident of notice MS38, comprise that at least when incident begins, and distributes to the time span of this time.MS38 and the base station in its AS forbid that during special incident call recovery triggers the starting call recovery.

In the embodiment of alternative, the group of MS38 notice BS1 32 special incidents on the horizon or these special incidents.Respond this notice, BS1 32 can approve this special incident, forbids this incident, or reschedules this incident.And this just provides enough information to MS38 and the base station in its AS, is forbidding that during special incident call recovery triggers.

What therefore, propose here is the novelty of keeping in communication in wireless telecommunication system and the method for improvement.When the link between the little service area base station, source of mobile radio station and correspondence got into trouble, mobile radio station and fabric had been rearranged potential redemption base station.The neighbour station of all energy call recoveries is got in touch as potential reetriever in little service area base station, source.The neighbour station of energy call recovery has the predetermined default channel that is adapted in the mobile radio station soft handover.During the beginning part of switching, default channel is just temporary transient to be used.Each saves the base station is ordered use silent approvement passage in saving transmission.Save transmission and think the call recovery operation.Mobile radio station is set up soft handover with saving the base station, and wherein FL uses default channel.Save the base station then in other passage starting transmission.Finish in case switch, save the base station and aspect this mobile radio station transmission, stopping using the silent approvement passage.In one embodiment, the little service area in source base station during the transmission and occur before the communication link problem providing the table at neighbour station that can call recovery as additional information to mobile radio station.In this way, for the situation of the failure of FL before receiving handover information, mobile radio station has enough information to switch.

In yet another embodiment, specify a plurality of default channel for stand BS2 34 of neighbour.Use a plurality of acquiescences or save the call recovery energy that passage has increased system 10.Then, each adjacent station, can participate in a plurality of as MS38 the call recovery of mobile radio station.In operation, before call recovery, the little service area BS1 32 in source provides identifier corresponding to a plurality of passages relevant with BS2 34 to MS38.MS38 and BS2 34 store the certainty function as hash function, and identifier is mapped to special modality.Use especially pseudo-random process of hash function.In addition, specify electronic serial number to MS38.Electronic serial number can deposit MS38 in or offer MS38 when call recovery.When call recovery, the little service area BS1 32 in source offers BS2 34 with the electronic serial number of MS38.BS2 34 and MS38 all use the suitable default channel of predetermined function calculation.

The hash function of data structure is enabled only to use of database to be soundd out message pick out keyword in one group of speech.Hash function is mapped to its independent variable the result of predefined type.Hash function be determine with stateless.That is, return value only depends on independent variable, and the independent variable that equates produces the result who equates.Importantly hash function is wanted minimum collisions, and wherein collision is defined as and hashes to two of sample value different independents variable.The distribution that it is also important that hashed value is uniform; That is, hash function returns the probability of any particular value of predefined type to return the probability of any other value identical with it roughly.In the embodiment of alternative, a plurality of default channel in the time of utilizing the cipher function of other form to be used to be identified in call recovery.

For example, the logical block of various examples is described in conjunction with the embodiment that discloses here, module, circuit, can use digital signal processor (DSP) with algorithm steps, application-specific integrated circuit (ASIC) (ASIC), field-programmable gate array (FPGA) or other programmable logic device, the door or the transistor logic that separate, the nextport hardware component NextPort that separates as register and FIFO, carry out the processor of one group of firmware instructions, any combination that function described herein is finished in any traditional programmable software modules and processor and design realizes.Processor is microprocessor preferably, but alternatively processor can be any traditional processor, controller, microcontroller, or state machine.Software module can reside in the RAM memory, the ROM memory, and eprom memory, eeprom memory, register, hard disk can be taken dish away, in the storage medium of any other form that CD-ROM or this specialty are known.Processor can be included in the ASIC (not shown).ASIC can be placed in the phone (not shown).Alternatively, processor can be included in the phone.Processor can be as the combination of a DSP and a microprocessor, or as the combination realization of two microprocessors that are connected with the DSP core.

Provide the front of preferred embodiment to describe, made any professional skilled person make or use the present invention.Various modifications to these embodiment are conspicuous to this professional skilled person, and the General Principle of Que Dinging can be applied to other embodiment and need not use creativity here.Therefore, the present invention does not attempt to be limited to the embodiment that illustrates here, but according to the principle and the corresponding to scope the most widely of novel feature that disclose here.

Claims

1. equipment in having the wireless telecommunication system of a plurality of base stations, each of wherein said a plurality of base stations has the neighbour station group that comprises adjacent base station, and each adjacent base station has default channel, and described equipment comprises:

Be used to send the device of default channel information to mobile radio station;

Be used to detect the device of the appearance that call recovery triggers; With

Be used for when detecting the appearance of call recovery triggering the device of ordering all base stations in the group of neighbour station in default channel separately, to send.

2. equipment as claimed in claim 1 is characterized in that, call recovery takes place when forward direction link signal quality is lower than predetermined threshold trigger.

3. equipment as claimed in claim 1 is characterized in that, triggers at following situation generation call recovery: confirm from the first next message of mobile radio station; With

After confirming first message, receive first message and reach pre-determined number from mobile radio station.

4. equipment as claimed in claim 1 is characterized in that, also comprises:

Be used to set up the device with the soft handover of adjacent station group, wherein each adjacent station group is sending on the passage in addition.

5. equipment as claimed in claim 4 is characterized in that, also comprises:

Be used for receiving the device of handoff completion message from mobile radio station.

6. equipment as claimed in claim 1 is characterized in that, also comprises:

The device that is used for the activity group of definite mobile radio station.

7. equipment as claimed in claim 6 is characterized in that, also comprises:

Be used for receiving from mobile radio station the device of pilot signal measurement message, pilot signal measurement message comprises one group of signal of base station ionization meter; With

Be used for to organize the device that the base station is assigned to movable group.

8. equipment as claimed in claim 6 is characterized in that, at least one base station obtains from the next signal of mobile radio station in the group of neighbour station, and this equipment also comprises:

Be used to specify at least one base station and give the device of movable group.

9. equipment as claimed in claim 1 is characterized in that, the first adjacent station in the group of neighbour station has a plurality of default channel.

10. equipment as claimed in claim 9 is characterized in that, mobile radio station uses the certainty function to determine that one of a plurality of default channel are used for call recovery.

11. the equipment as claim 10 is characterized in that, this determines that function is a hash function.

12. the equipment as claim 10 is characterized in that, first identifier is relevant with this mobile radio station, and this equipment also comprises:

Be used to send the device of first identifier to the first adjacent station; With

Being used for the order first adjacent station uses the definite function and first identifier to determine that one of a plurality of default channel are used for the device of call recovery.

13. method that is used for wireless device, wherein said wireless device comprises antenna, is connected in the processor that is used to carry out described method of antenna, is connected in the transmitting line of antenna and processor and is connected in antenna and the receiving lines of processor, and described method comprises:

The neighbour who receives the base station table of standing, this table comprises the default channel appointment for each adjacent station;

The identification call recovery triggers also forbids transmitting line in response; And

Set up switching with at least one adjacent station.