CN1592485A - Trans-zone switchover method for phs personal station - Google Patents
Trans-zone switchover method for phs personal station Download PDFInfo
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- CN1592485A CN1592485A CN 200410078669 CN200410078669A CN1592485A CN 1592485 A CN1592485 A CN 1592485A CN 200410078669 CN200410078669 CN 200410078669 CN 200410078669 A CN200410078669 A CN 200410078669A CN 1592485 A CN1592485 A CN 1592485A
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Abstract
PHS personal station. Signal reception quality is detected intermittently during a speech. In the case a high speed hand-over processing criterion is not satisfied as a result, while keeping radio connection with respect to a speech from a radio connection destination CS (stationary station) so far, remaining transmission reception systems not used for a speech are used to detect other CS and to execute calling procedures for establishment of the radio connection with the CS thereby reducing a speech interruption time. In the case of switch-back, the similar procedure is executed and speech interruption due to switch-back operation can be prevented during high speed movement.
Description
The present invention relates to PHS (personal handyphone system) personal station, more particularly, relate to the method for handover of this personal station.
In the current mobile communication system of popularizing very much, for example in cell phone system or PHS system, a plurality of (normally a large amount of) cell site that distributed on the geography (Cell Station, CS).Each CS covers a limited geographic range (sub-district).The cell site collaborative work of this system covers whole urban district together.System user usually carries the platform of people one by one (PS) that can be placed on the palm.When need communicate, this user controls this personal station, sends to other platform and calls out or from other receipt of call.For example, in the PHS system, each CS passes through public switch telephone network (PSTN) etc. and is connected with other CS or other mobile communication system.Therefore, PHS user can with other PHS telex network, communicate by letter with the ordinary telephone subscriber that is connected to PSTN, perhaps with the telex network of other mobile communication system.In the application's explanation, " communication " this term not only comprises voice communication, also comprises other communication that image data communication is such.
Fig. 9 has provided the structure example of a PS who is used for this PHS system.PS shown in the figure comprises an antenna 10, radio unit 12, signal processor 14, memory 16, operating unit 18, display 20, a microphone 22 and a loud speaker 24.Though do not draw among the figure, also have one be the power circuit that these PS parts are powered, and be used for and personal computer or the device that is connected with personal digital assistant.Antenna 10 is used for sending or received signal.Radio unit 12 comprises radio frequency integrated circuit or the like, is used for sending signal or received signal by antenna 10.Signal processor 14 comprises ASIC (application-specific integrated circuit (ASIC)) etc., is used to carry out various Digital Signal Processing.Memory 16, RAM or F-ROM are for signal processor 14 provides memory space.Operating unit 18 is equipped with button and dial above, is used for sending instruction according to user's input to signal processor 14.Display 20, small-sized liquid-crystal apparatus etc. are used for the operating state of function menu, signal processor 14 and the state that transmits and receives of signal.Microphone 22 converts user's voice to the signal of telecommunication, input signal processor 14.Loud speaker 24 will become voice output from the electrical signal conversion of signal processor 14.
14 li of signal processors, 28, TCH-CODEC30 of 26, ADPCM-CODEC of a MPU (microprocessor unit) (encoder/decoder), a TDMA-TDD controller 32 and π/4 QPSK modulator-demodulators 34 are arranged.User's voice is sent to signal processor 14 by microphone 22.ADPCM-CODEC28 according to ADPCM (adaptive difference pulse code modulation) mode with the voice scrambling of receiving.The quantification speech coding of TCH-CODEC30 to receiving produces TCH (Traffic Channel) signal.This signal that produces through coding sends to π/4 QPSK modulator-demodulators 34 by TDMA-TDD controller 32.Modulator 36, parts of π/4 QPSK modulator-demodulators 34 are modulated this signal according to π/4 QPSK (quadriphase PSK) mode.38 pairs of these modulation signals of radiating circuit in the radio unit 12 amplify and frequency conversion, and send antenna 10 to and carry out radio transmission.
On the other hand, the receiving circuit 40 of 12 li of radio units signal that antenna 10 is received amplifies and frequency conversion.Demodulator 42, parts of π/4 QPSK modulator-demodulators 34, according to π/4 QPSK modes to this frequency variation signal demodulation.Then with the signal of this demodulation by TDMA-TDD controller 32 send to TCH-CODEC30, by the TCH-CODEC30 decoding, regenerate according to the ADPCM mode and from loud speaker 24 outputs by ADPCM-CODEC28.MPU26 is used for the entire work process of control signal processor 14.What the numeral 44 among the figure was represented is a duplexer, and it makes that radiating circuit 38 and receiving circuit 40 can shared this antennas 10.
The TDMA-TDD controller 32 here is according to the emission and the modulating/demodulating of TDMA-TDD (time division multiple access-time duplex) agreement control signal, and this agreement is the multiplexing method that uses in the PHS.Each carrier wave among the PHS all has four up (PS-〉CS)/descending (CS-〉PS) time slot.In PHS, the PS that send calling or receipt of call at first sends a request by control channel.Then by nearest CS for this PS distributes a time slot, utilize this distributed time slot, this PS sends and receives the signal that constitutes TCH.
Comprising in the mobile communication system of PHS that the PS that will be connected with CS selects the CS of top-quality signal will be provided to PS.For example, PS selects that the strongest CS of received electric field strength at that time from PS can receive all CS of signal.But when user or this PS move in the process of communication,, may descend from the received signal quality of the signal of the CS of this connection along with the difference of the direction of motion.And when on the moving direction at this PS another CS being arranged, the quality of signals that receives from the CS that is just connecting can descend, and the signal of another CS on the direction of motion then is to improve.In this case, this PS this CS that dedicated radio link was being connected just now from PS switches to the CS that is positioned on this PS direction of advance.This is called handover (handover).In PHS, the geographic range that each CS can cover (sub-district) little than in other conventional system, to compare handover also just more frequent with other system.
Figure 10 has provided the flow process that handover begins algorithm, and Figure 11 then provided the flow process of handover processing.This processing, for example, the processing in the PS shown in Figure 9 is to be undertaken by the signal processor 14 of collaborative work and the circuit in the radio unit 12 under the control of MPU26.The basis of this processing is the information from radio unit 12 and TDMA-TDD controller 32, and the fiducial value that is stored in 16 li of memories.
At first, as shown in figure 10, suppose that this PS is just in communication process.That is to say that TCH has set up the connection of a CS so that communicate (100).In the process of communication, signal processor 14 was checked the quality (102) of a received signal every 1.2 seconds.Signal processor 14 receives RSSI (received signal volume indicator) signals from the receiving circuit 40 of radio unit 12, this signal instruction be the electric field strength of received signal, and calculate the rolling average of up-to-date 240 frame level, obtain incoming level L.Also have, it checks the last 240 frames output of TDMA-TDD controller 32 and TCH-CODEC30, obtains FER (FER (Floating Error Rate)) (104).In a word, incoming level L is high more, and received signal quality is just good more, and FER (Floating Error Rate) FER is low more, and received signal quality is just good more.
Cross after the received signal quality through calculating inspection, signal processor 14 with FER (Floating Error Rate) FER and received signal level L and corresponding handover processing level ratio than (106,108).The handover processing level THF1 of FER (Floating Error Rate) FER is for example 24.The handover processing level THL1 of incoming level L is 22dB μ V for example.If satisfy FER 〉=THF1 and L≤THL1 simultaneously, signal processor 14 just adds 1 (110) on variable N; Otherwise signal processor 14 composes zero (112) just for variable N.When N equals 2, that is to say as above-mentioned two condition FER 〉=THF1 and L≤THL1 and when being met again (114), just finished above-mentioned sequence, i.e. 200 li quality examination sequence among Figure 11 with interior time period of 1.2 seconds.Control program is got back among Figure 10 the CS checking sequences with 116 signs, perhaps among Figure 11 with the 202 CS search sequences that identify.
The CS search sequence with 300 milliseconds of times from contiguous CS received signal, and assessment is found out a candidate CS as new dedicated radio link target by the signal quality that control channel receives.As a result of, if found a CS, its received signal quality is fine, satisfy predetermined handoff target zone and (for example select level, the incoming level of 24dB μ V), signal processor 14 is just carried out calling sequence, sets up dedicated radio link (118 among Figure 10) with this CS that finds out.Partly omitted this sequence in Figure 11, this sequence is carried out in the following manner.Send a link channel request by one of control channel SCCH, request distributes time slot, is used to carry out radio communication and connects, and responds this request and receives the link channel distributing signal, utilizes distributed time slot exchange lock-out pulse string signal.After as the FACCH of one of control channel UA being sent to CS, the end call sequence is received this CC response by one of control channel SACCH from CS then.
As mentioned above, from detecting whether degenerate handover processing in the conventional P HS of beginning of received signal, comprise CS search sequence and following calling sequence.A problem of this processing mode is to communicate to connect to be disconnected in the handover processing process, shown in Figure 11 right side.
The reason that radio communication must disconnect temporarily is that PHS has adopted so-called autonomous distributed dynamic channel to distribute.That is to say that with always synchronous different of CS in the cellular system, these CS are always not synchronous in PHS.Sometimes it is overlapping that this can cause the TCH time slot of the control channel time slot of a CS and another CS.Owing to this reason, must disconnect earlier with the dedicated radio link of old dedicated radio link target CS (handover source CS), could begin the CS search sequence then, thereby this CS search sequence can be carried out, as shown in figure 11.On the other hand, after this calling sequence is finished, set up dedicated radio link with a new dedicated radio link target CS (handoff target CS).So, to disconnect in the period at this section and to communicate to connect, this section period had 2 seconds long.
The present invention attempts to solve the problem in the above-mentioned prior art.An object of the present invention is in the process of handover, to shorten the time that communication disconnects, reduce PS user's discomfort.Even another object of the present invention is to make PHS user just in fast moving, for example also can continue to communicate by letter comfily ON TRAINS the time.
Using a system of the present invention is PHS.In PHS, a plurality of PS have been adopted, each is all carried by a user, and each PS all according to the TDMA-TDD agreement with a kind of autonomous distributed way and a plurality of interconnecting (for example passing through PSTN), keep dedicated radio link by one among the CS of geographical distribution.Method of handover of the present invention is carried out by having set up the PS that is connected with the radio communication of a CS.That is to say, this PS set up carrying TCH with being connected of CS.
The invention provides two handover sequences: common handover sequence and seamless handoff sequence.Common handover sequence disconnects has the radio communication of the CS (the source CS of handover just) of dedicated radio link to be connected with current, search for the current CS that can carry out dedicated radio link, and, if a current CS that can set up dedicated radio link is arranged, just set up dedicated radio link to communicate by letter with this CS (handoff target CS just).This sequence belongs to prior art.On the other hand, the seamless handoff sequence belongs to improvement of the present invention.
The seamless handoff sequence allows new CS of second circuit search, and personal station might be set up dedicated radio link with this new CS, keeps radio communication by first circuit with the current CS that dedicated radio link arranged simultaneously and is connected.If so new CS is arranged, personal station may connect with it very soon, and this sequence is just set up a new dedicated radio link, to communicate by letter with this new CS (handoff target CS just) by second circuit.On the other hand, set up before good this new dedicated radio link, this sequence is kept this dedicated radio link by first circuit, up to a predetermined instant.If there is not so new CS, this seamless handoff sequence is just kept current dedicated radio link state.
The feature of method of handover of the present invention also is its definite method, perhaps determines to adopt the level of common or seamless handover method.Particularly, this method of handover of the present invention is intermittently checked the received signal quality of the CS that current wireless is electrically connected.Be lower than the limiting level that can keep dedicated radio link with the current CS that dedicated radio link arranged if detect received signal quality, this method is just carried out common handover sequence.If when detecting received signal quality and being lower than seamless handoff and handling level, this level is configured to than the limiting level height of keeping connection, this method is just carried out the seamless handoff sequence.
The present invention is also relevant with PS.PS in the present invention is the PHS PS that a user carries, it according to the TDMA-TDD agreement with autonomous distributed way with set up dedicated radio link by one among interconnected a plurality of CS of geographical distribution.PS in the present invention comprises a plurality of circuit, is used for modulation signal and transmitting to CS, meanwhile, receives to conciliate and transfers from the radio signal of this CS.This PS also has a controller, first circuit that is used to communicate by letter according to received signal quality control be not used in second circuit of communicating by letter, to realize method of handover of the present invention.This first circuit and second circuit are included in described a plurality of circuit.
In method of the present invention, when intermittent received signal quality check result explanation received signal quality has descended or descended, just carry out in two handover sequences.Begin or select this two handover sequences according to two criterions: one is the threshold value of keeping with the radio communication of the current CS that is connected, (common) handover processing level just, another is that seamless handoff is handled level, and it is higher than above-mentioned threshold value.That is to say, be lower than this threshold value, just carry out this common handover sequence if detect received signal quality; Handle level if received signal quality is lower than seamless handoff, just carry out the seamless handoff sequence.
Common handover sequence at first disconnects with the radio communication of the current CS that is connected and connecting.Then, the current CS that can carry out dedicated radio link of this sequence search.For example, as what introduced, by received signal in the time of a predetermined length, search for such CS in prior art, this CS can make received signal quality be higher than (being better than) predetermined handoff target and select level.If such CS is arranged, this sequence is just set up a new radio communication with this CS and is connected (just a TCH connects).It is by sending the link channel request for allocation, receiving the channel that distributes and exchange the lock-out pulse string signal by TCH by control channel and set up that this radio communication connects.
In order to carry out the emission/reception of radio signal when setting up new the connection, the seamless handoff sequence adopts first circuit and second circuit in a plurality of circuit in the PS.That is to say that the seamless handoff sequence adopts second circuit search PS will soon set up a new CS of dedicated radio link with it, and meanwhile, keep radio communication with the CS of first circuit and current wireless electrical connection and be connected.If the new CS that has such PS to connect with it very soon, this sequence is just set up a new radio communication with this new CS and is connected.With communicating by letter of new CS, for example the transmitting chain channel assignment request is finished by second circuit.Be connected and when communicating, keep by first circuit as much as possible in order to set up radio communication at second circuit, thereby guarantee communication seamlessly just substantially continuously with this new CS with the communication of the current CS that is connected.
The difference of common handover sequence and seamless handoff sequence is to disconnect the length of call duration time.Common handover sequence requires to disconnect with the dedicated radio link of handover source CS, just begins to search for handoff target CS then.On the other hand, the seamless handoff sequence allows first circuit to keep dedicated radio link, thereby connects continuation communication by this, will set up up to the dedicated radio link by second circuit at once.This opening time that just means seamless handoff sequence needs is shorter.
Another difference of these two sequences is the beginning level of sequence.The beginning level of common handover sequence is a limiting level keeping communication with the current CS that is connected, and the beginning level of seamless handoff sequence is a seamless handoff processing level, and it is configured to be higher than above-mentioned limiting level.Owing to this reason, when the received signal quality of the CS of current connection does not also drop to the degree that communication will be interrupted, but just begin the seamless handoff sequence when can significantly descend along with the mobile expection signal quality of PS.An advantage of the invention is that the seamless handoff sequence carries out just beginning before the handover at actual needs, this seamless handoff sequence is a modified version of handover sequence.Communication can be continued, even the user who carries this PS is just in fast moving.
In addition, method of the present invention combines the execution function of common handover sequence and the execution function of seamless handoff sequence.Owing to be the position of intermittently checking received signal quality or depending on this CS, the beginning level of common handover sequence may just be satisfied before the seamless handoff sequence begins.Even the execution function that combines is used for carrying out in this case handover.In addition, in the process of carrying out the seamless handoff sequence, the beginning level of common handover sequence may be met.Clash for fear of these two sequences, do not start common handover sequence, the seamless handoff sequence then continues.That is to say, when the seamless handoff sequence is being carried out,, also do not begin common handover sequence even the received signal quality of the CS of current connection is lower than limiting level.So just can guarantee level and smooth and correct handover.
For example, common handover sequence is sought a CS, expects that received signal quality that it can provide is better than the selection level in predetermined handoff target zone, selects it as new dedicated radio link CS then.Be higher than handoff target zone selection level by allowing seamless handoff handle level, prevented that execution seamless handoff sequence from causing received signal quality to descend, common handover sequence can be searched for the relatively poor relatively target CS of received signal quality simultaneously.Therefore, seamless handoff sequence of the present invention not only refers to the handover sequence with regard to carrying out before needs carry out handover.On the contrary, seamless handoff sequence of the present invention also refers to carry out the sequence of handover with the received signal quality that obtains to be better than common handover sequence and can obtain.In this way, even near cell boarder, the seamless handoff sequence also can be kept the received signal quality that can't obtain with common handover sequence.
In addition, the seamless switching sequence is utilized second circuit received signal in the time period of a predetermined length, thereby search expection received signal quality will good CS than the signal quality of the CS of current connection.If such CS is arranged, this sequence just with this CS as setting up the candidate CS that radio communication is connected by second circuit and its.Then, this sequence is set up a new dedicated radio link, does the CS communication of candidate CS (among perhaps several CS one is if having two or more such CS) with choosing.In this case, only select those its received signal qualities all to be higher than the CS of predetermined value, guarantee that received signal quality can improve before and after handover.That is to say, search for another CS, expect that received signal quality that it provides will be better than the signal quality of the CS of current connection, and set up one and be connected, the signal quality of the CS of the current connection received signal quality that is beyond one's reach can be provided on the border of sub-district with the radio communication of this CS.When the number of the CS that the received signal quality that provides when expection is better than the signal quality of current connection CS surpasses a predetermined number, only select the best CS of a predetermined received signal quality as candidate CS.The relatively poor relatively CS of received signal quality has not only been cast out in this selection, and has saved the space of depositing or store candidate CS information in the PS.
If a plurality of candidate targets are arranged, this seamless handoff sequence just repeats to select candidate target, selects one at every turn, is used for attempting setting up dedicated radio link by second circuit, up to all selected pre-determined number of crossing of all candidate targets.If this time slot has obtained successful distribution, this sequence is just set up radio communication with this CS and is connected.This has been avoided using the time of seamless handoff sequence oversize.As a result, along with the fast moving of PS, even second electric circuit inspection to received signal quality variation has taken place at short notice, current state also can correctly be reflected in the quality that detects, therefore, the seamless handoff sequence has obtained correct execution.
This seamless handoff sequence can also be used for preventing that communication disruption from appearring in the process switching back.Usually, when the received signal quality of the CS of current connection descended, handover just began to disconnect the dedicated radio link with this CS, searches for another new CS then.If this sequence is not found out the new CS that can set up dedicated radio link in this search procedure, this sequence is just carried out the operation (operation that just switches back) of setting up dedicated radio link again with this CS that dedicated radio link was arranged just now.Yet, if this sequence fails to find the CS that can set up dedicated radio link, and meanwhile, this PS is promptly leaving the old CS of dedicated radio link, received signal quality can further descend, thereby can't carry out the operation that switches back to rebulid this connection.In order to address this problem, the preferred embodiments of the invention allow in first circuit and second circuit one, and for example first circuit is carried out the operation that switches back, and another, for example second circuit then carried out the seamless handoff sequence.In normal CS position, when PS was leaving a CS, this PS was near another CS.Like this, utilize first circuit and second operation and seamless handoff that circuit is carried out to switch back simultaneously, also can prevent communication disruption even when PS moves rapidly, carry out the operation that switches back.
In one embodiment of the invention, PS is configured to carry out the seamless handoff sequence.That is to say, a plurality of circuit corresponding to these functional parts (from antenna or radio unit to signal processor) are provided.When first circuit, in promptly a plurality of circuit one is when having a radio communication to be connected with a CS, controller is (corresponding to the parts of signal processor, MPU particularly) can use second circuit, promptly a circuit in other circuit is carried out this seamless handoff sequence.This a plurality of circuit are provided in this way, make the seamless handoff sequence to carry out at an easy rate, this is one of advantage of the present invention.
Can construct these a plurality of transmitting/receiving systems in several ways.A kind of mode provides at least two circuit, and each circuit all has modulation/radiating circuit and reception/demodulator circuit (two emissions/double reception pattern).This modulation/radiating circuit is a series of circuit, be used for modulation signal and emission modulation signal, and receive/demodulator circuit is a series of circuit that receive radio signals and the signal of receiving is carried out demodulation from CS.In this pattern, controller can utilize the modulation/radiating circuit of first circuit and reception/demodulator circuit keep with the old CS that dedicated radio link is arranged between radio communication be connected, up to utilize second circuit set up new communicating to connect before a scheduled time.In fact this mode makes the time of communication disruption drop to 0.
Provide the another kind of method of at least two transmitting/receiving systems to be, each system all has a reception/demodulator circuit to be used for receiving the radio signal of CS, and the signal of receiving carried out demodulation, but a modulation/radiating circuit is shared by these two systems, is used for modulation signal and launch modulated radio signal and give CS (single transmit/double reception pattern).When communicating by one of first circuit and second circuit, shared modulation/radiating circuit is used to transmit to communicate with the CS that dedicated radio link is arranged.When carrying out the seamless handoff sequence, sharing modulation/radiating circuit is used to keep and the dedicated radio link that the old CS of dedicated radio link is arranged, transmit up to needs and to communicate by letter, thereby transmit, be used for and have the new CS of dedicated radio link to communicate with a new CS.This switching is to finish under the control of controller.In this mode, begin to transmit to attempt to set up the moment of dedicated radio link at modulation/radiating circuit of sharing with new dedicated radio link target, and and the new target CS that dedicated radio link is arranged set up between the moment of dedicated radio link, communication is disconnected.So, to grow though disconnect the opening time of the two emission/double reception patterns of time ratio of communication, it is shorter than the opening time in the prior art.In addition, the circuit of this mode is littler than the circuit of two emission/double reception patterns.
In addition, single transmit/double reception pattern can realize (an extra modulation/radiating circuit is arranged) in the PS that has disposed two emissions/double reception pattern.Under given conditions, fill order's emission/double reception pattern is more better sometimes in the PS with two emission/double reception patterns.That is to say that if to be used for the time slot of the dedicated radio link of the current target CS that is connected be to be distributed in the process of carrying out the seamless handoff sequence by new dedicated radio link target CS, controller just allows first circuit disconnection of wireless be electrically connected.This function has prevented that PS from receiving the signal that it produces itself, and solves because up/downlink transfer has been used 4 time slots the time slot collision problem that the probability with 1/8 takes place.
In the method for the invention, carry out communication weak point opening time of the common handover sequence of communication ratio opening time execution of seamless handoff sequence.In addition, method of the present invention was just carried out the seamless handoff sequence before the actual needs handover, made communication to continue, and can not occur interrupting, even the user who carries PS is just in fast moving.Further, common handover sequence is carried out function to method of the present invention and seamless handoff sequence execution function combines, make it possible to carry out handover, begin condition even before carrying out the seamless handoff sequence, satisfied common handover sequence.In the preferred embodiments of the invention, also have other effect, introduce as front or back.
Fig. 1 is a block diagram of PS configuration in one embodiment of the invention.
Fig. 2 is the flow chart that handover begins sequence in this embodiment.
Fig. 3 is the sequential chart of seamless handoff in two emission/double reception patterns.
Fig. 4 is a schematic diagram of explanation time slot coincidence status.
Fig. 5 is the flow chart that switches between two emission/double reception patterns and the single transmit/double reception pattern.
Fig. 6 is the sequential chart of seamless handoff stream in single transmit/double reception pattern.
Fig. 7 is the flow chart of the operation that switches back.
Fig. 8 is the sequential chart that the operation that switches back is described.
Fig. 9 is a block diagram of common PS profile instance.
Figure 10 is the flow chart that the common handover of explanation begins sequence.
Figure 11 is a sequential chart of explanation handover stream.
Introduce a preferred embodiment of the present invention below with reference to the accompanying drawings.Numbering corresponding to the parts of those parts in Fig. 9 ~ 11 is identical, therefore no longer repeats to introduce these identical parts.
Fig. 1 is the configuration of the PS that uses in the PHS system in one embodiment of the invention.PS among this figure has similar hardware configuration to traditional PS shown in Figure 9 except signal emission/receiving-member is doubled.That is to say that the modulator and demodulator among reception/radiating circuit among antenna, duplexer, the radio unit 12A and π/4 QPSK modulator-demodulator 34A all has two.In addition, TDMA-TDD controller 32A in signal processor 14A and among the TCH-CODEC30A each all comprise control and the processing capacity that is used for two transmitting/receiving systems.In the figure, the numbering of the parts relevant with first transmitting/receiving system in first circuit has been added " 1 ", and the numbering of those parts relevant with second transmitting/receiving system in second circuit has then been added " 2 ".
Different in this embodiment among the circuit arrangement of PS and circuit function and the common PS.But this is not unique difference.PS in this embodiment not only utilizes the handover processing level of common PS and handoff target zone to select level, and utilized a new seamless handoff to handle level and a seamless handoff target area selection level difference, in them each all is stored in the memory 16A, for example be stored in the EEPROM, be used to carry out handover processing.
Fig. 2 has provided the beginning sequence of handover processing, and Fig. 3 has provided the signal sequence in the seamless handoff processing procedure.Suppose to utilize in two transmitting/receiving systems one to set up dedicated radio link (100), as shown in Figure 2 with a CS.In the following description, suppose that this communication carries out with first transmitting/receiving system.A MPU26A among the signal processor 14A checked the quality of signals (102) that once is electrically connected target CS from current wireless every 1.2 seconds.That is to say that MPU26A calculates the moving average of last 240 frame RSSI signals, therefrom find out incoming level L (104).It also writes down the mistake number of times in last 240 frames, thereby calculates FER (Floating Error Rate) FER.
Then, MPU26A carries out the beginning sequence of common handover sequence and the beginning sequence of seamless handoff sequence simultaneously.The beginning sequence of the common handover sequence almost conventional sequence with shown in Figure 10 is identical.Exception be, when carrying out the seamless handoff sequence, stop common handover sequence, step 112 (120) is given in control.This processing has prevented that common handover sequence from conflicting with the seamless handoff sequence.That is to say, even the beginning sequence of common handover sequence is met (106,108,114), if but carrying out the seamless handoff sequence, just can continue the seamless handoff sequence.Like this, MPU26A can select to have the CS of better received signal quality, and earlier finishes handover.First transmitting/receiving system that common handover sequence is used by current communication is carried out.
The beginning sequence of seamless handoff is carried out in the following manner.At first, MPU26A checks whether step 104 a li incoming level L who calculates is equal to or less than seamless handoff and handles level THL2 (122).THL1 compares with the handover processing level, and seamless handoff is handled level THL2 and is configured to a value, and this value is enough big, is enough to keep this radio communication and connects.Also be necessary to make seamless handoff handle level THL2 or seamless handoff handle level THL2 and seamless handoff target area select level difference X's and greater than handoff target zone selection level, thereby make seamless handoff can improve received signal quality as much as possible.If according to noted earlier handover processing level THL1 is arranged to 22dB μ V, and select level to be arranged to 34dB μ V the handoff target zone, seamless handoff is handled level THL2 and just should be arranged to for example 35dB μ V so.If do not satisfy L≤THL2, just be electrically connected target CS and communicate by current wireless.
If a li L≤THL2 is met in step 122, so MPU26A just utilize second transmitting/receiving system with 300 milliseconds time received signal to select candidate cell or candidate CS (124), this second transmitting/receiving system is different with that system that current communication relates to.That is to say that when utilizing first transmitting/receiving system shown in Figure 3 to communicate, the step 124 of MPU26A in Fig. 2 li utilized second transmitting/receiving system search CS (202A).If this CS search procedure has been found one or more CS (126), the signal incoming level of each all exceeds at least one predetermined seamless handoff target area than step 104 a li signal incoming level L who calculates and selects level difference X (dB), MPU26 just under the control of TDMA-TDD controller 32A, is handoff target candidate CS with the CS choosing of all acquisitions so.Perhaps, MPU26 is according to this CS of level L selection predetermined number, to save storage space.The seamless handoff target area selects level difference X to be configured to, for example, and a value in 6dB ~ 10dB scope.In a word, the received signal level of a plurality of CS being arranged is L+X (dB) or higher.Meanwhile, the storage space that stores candidate CS should be controlled at Min..For this reason, in step 126 li, MPU 26A equals or is higher than the CS of the predetermined number (for example 8) of selecting to have the highest signal incoming level a plurality of CS of L+X (dB) from the signal incoming level.The information of all the other CS is eliminated.
Next step, MPU26A is from selecting one (128) among the step 126 li candidate CS that elects.For example, MPU26A does not finish the candidate CS that selects to have best received signal quality the candidate CS that link channel distributes as yet from those.MPU26A sends a link channel request for allocation (130) by second transmitting/receiving system to the candidate CS that chooses.This is to utilize the SCCH as one of control channel to finish.Distribute if MPU26A has successfully received a link channel by SCCH from candidate CS there, that is to say, be assigned to time slot and be used for TCH (132), it just continues communication, utilizes second transmitting/receiving system to set up a dedicated radio link (134).For example, it utilizes these time gas exchange lock-out pulse string signals.On the contrary, do not distribute if receive link channel, MPU26A just gives step 128 with control, and the link channel request for allocation is sent to next candidate CS.Note, when the number of times of attempting to send the link channel request for allocation has reached maximum (for example twice (136)), during perhaps next never again candidate CS (138), MPU26A just abandons the handover that utilizes the seamless handoff sequence to carry out, and gives step 100 with control.
As mentioned above, the calling sequence of setting up dedicated radio link before communication is a sequence of following communication steps: send a link channel request for allocation, receive a link channel assignment response, exchange lock-out pulse string signal, and launching/receiving unshowned signal and receive the CC response later on.Send UA or receive CC when response, be connected with a radio communication of a new dedicated radio link target CS (handoff target CS just) and be established.Therefore, when adopting the seamless handoff sequence, still continue with old communicating by letter of CS (handover source CS), up to sending UA or receiving that CC responds with first transmitting/receiving system.In this embodiment, it is very short to this means that the process of carrying out the seamless handoff sequence breaks time of communication.Under the longest situation of this time, it equal from send UA the time be carved into a period of time between the moment of receiving the CC response.Compare with conventional handoff sequence shown in Figure 11, wherein from find CS (202) the time be carved in time between the moment of receiving CC response, communication is disconnected, and the seamless handoff sequence in this embodiment obviously makes PS user obtain a level and smooth handover.
For important being of implementing to bring above-mentioned advantage of seamless handoff sequence, under the control of seamless handoff processing level THL2 and seamless handoff target area selection level difference X, carry out handover.But the improvement that this embodiment is brought is not limited to introduce and increases new handover sequence (seamless handoff sequence).
At first, when the condition of seamless handoff processing level THL2 and seamless handoff target area selection level difference X definition is met, just carry out the seamless handoff sequence in this embodiment.That is to say, have only the received signal quality in first transmitting/receiving system to begin to descend, and near another CS having found, expect when it can guarantee that received signal quality is higher than the received signal quality of current wireless electrical connection target CS, just carry out the seamless handoff sequence.In other words, in this embodiment, there is no need to carry out common handover sequence, if but carried out handover and will obtain just carrying out the seamless handoff sequence under the situation of better received signal quality.Therefore, PS in this embodiment can improve received signal quality, particularly the boundary vicinity in the sub-district can improve received signal quality, meanwhile, make the user can continue communication, even the user who carries this PS is just in fast moving, for example, (this is a measured value with 80 kilometers speed fast moving hourly.Theoretically, move with 200 kilometers speed hourly, also can improve received signal quality) even carry the user of this PS.
In this embodiment, according to circumstances begin to carry out common handover sequence, rather than the seamless handoff sequence.For example, when PS has moved quickly near position the cell boarder in the time (this time is the time interval of calculating incoming level L and FER (Floating Error Rate) FER) at 1.2 seconds, do not judge whether the condition of carrying out the seamless handoff sequence satisfies (perhaps double satisfy before this condition), the dedicated radio link with old linking objective CS can be difficult to keep sometimes.In this case, carry out common handover sequence in this embodiment.In this way, carry out seamless handoff sequence and common handover sequence selectively, intermittently check received signal quality simultaneously.
Moreover the PS in this embodiment has two transmitting/receiving systems, is used to support the execution of seamless handoff sequence.Adopt a reason of this circuit structure to be, in the PHS as autonomous distribute type dynamic channel allocation system, CS is always not synchronous according to the mode in the cellular system.In the always synchronous cellular system of CS, the PLL in the receiving circuit can be synchronous with some other frequency short time, to check the received signal quality of another CS.Yet in PHS, the time slot that is used for the CS control signal in the sub-district in time with neighbor cell in the time slot that uses of the TCH of another CS may overlap or overlapping.For the PS in the overlapping region, sub-district, this requires step 116 or 124 li times of utilizing 300 milliseconds in Fig. 2 to carry out the CS search, in the period, stops the synchronous of TCH at this section.This requirement makes the disconnection of will communicating by letter during the CS search (202) in the conventional sequence shown in Figure 11.PS in this embodiment adopts second transmitting/receiving system that is not used in communication to search for CS, thereby makes the opening time of communication shorter than the time of common PS.
PS in this embodiment is with a communication in two transmitting/receiving systems, and searches for CS and carry out calling sequence with another transmitting/receiving system.The problem that this method causes solves with the following methods.
This problem illustrates with Fig. 4.That is to say, when the time slot that is used to communicate by letter in first transmitting/receiving system almost when handoff target CS distributed time slot in second transmitting/receiving system overlaps, as shown in Figure 4, PS can receive the radio wave of it oneself emission.Take place for fear of this situation, the PS in this embodiment has adopted following method.When handoff target CS (that CS that just utilizes second transmitting/receiving system that the link channel request for allocation is mail to) distributes the time slot that distributed by handover source CS (just first transmitting/receiving system be used to communicate by letter time slot) (300), under the control of MPU26A shown in Figure 5, adopt single transmit/double reception pattern rather than above-mentioned two emission/double reception pattern.
In two emission systems in this embodiment and two receiving systems, PS in single transmit/double reception pattern is used for emission with a system, two systems are used for receiving, be connected to keep radio communication with handover source CS, search for a CS as handoff target CS, CS sets up dedicated radio link with this handoff target.During step 134 in PS carries out this pattern, temporarily disconnect communication, as shown in Figure 6.This be because, obtain link channel at this PS from handoff target CS and divide timing, just force PS to adopt this emission system to distribute in link channel the time slot of gained and send synchronization pulse.In other words, this emission system that is used to till now to communicate by letter is exclusively used in and has exchanged pulse train and send a signal to handoff target CS later on.Therefore, compare with two emission/double reception patterns shown in Figure 3, the time that disconnects communication is longer; Yet, to compare with conventional handoff sequence shown in Figure 11, the time that disconnects communication is shorter.This method of utilizing PS in this embodiment realizes two emission/double reception patterns.
In this embodiment, when received signal quality in the communication process descends (204 in Fig. 8), and sequence shown in Figure 2 has started the operation (206) that switches back, so, MPU26A just allows the transmitting/receiving system (in this example, being first transmitting/receiving system) that has been used to communicate by letter carry out the operation that switches back.If the incoming level of the lock-out pulse string signal that the target CS that switches back sends is enough high, just can set up dedicated radio link with this CS; Otherwise, just can't rebulid dedicated radio link.Therefore, MPU26A allows first transmitting/receiving system receive the lock-out pulse string signal from the target CS that switches back.Simultaneously, according to the RSSI signal of receiving from first transmitting/receiving system in the receiving course of lock-out pulse string signal etc., MPU26A checks that whether the incoming level of lock-out pulse string signal is more than or equal to the level carried out that switches back (140 in Fig. 7).If do not receive lock-out pulse string signal more than or equal to this level carried out that switches back, MPU26A just allows other sound or vibrating mass of loud speaker 24 or some sound or vibrate, and provides the alarm signal (142) of having left service area.The incoming level of the time supervision lock-out pulse string signal in 10 seconds of the longest usefulness of MPU26A.If received that level more than or equal to switching back the lock-out pulse string signal that can carry out level, perhaps surpassed for 10 seconds before the time in this 10 second finishes, MPU26A just stops to sound or vibrating (144).
In traditional PS, if do not detect the lock-out pulse string signal of level more than or equal to this level carried out that switches back in 10 times in second, PS just can't set up dedicated radio link with any CS, and communication is disconnected.In this embodiment, because it is to carry out the operation that switches back with first transmitting/receiving system to carry out simultaneously that second transmitting/receiving system carried out the seamless handoff sequence, see Fig. 7 and Fig. 8, if the seamless handoff sequence has successfully been finished handover, communication does not just disconnect.In Fig. 7, the seamless handoff sequence is corresponding to step 124A ~ 138A and 102A.Treatment step in step 124A ~ 138A is almost identical with the step of step 124 ~ 138 li execution among Fig. 2.Be necessary that " the type of call handoff target is handled level again " in the step 126A is arranged to be higher than the handoff target zone selects level.In step 102A, measure with 1.2 seconds cycle as step 102.Step 202C in Fig. 8 is corresponding to step 124A, or the like.
In the above description, incoming level L and FER (Floating Error Rate) FER are used for checking and the assessment received signal quality.Implement to adopt when of the present invention other index.No matter where be, as long as need carry out handover, just can use the present invention, and no matter the type of agreement (commercial Application or public's application).When carrying out the seamless handoff sequence, this sequence can be switched to single transmit shown in Figure 5/double reception pattern according to the step among Fig. 7.
Claims (1)
1. method of handover that is used for PHS (personal handyphone system),
Wherein said method of handover has a seamless handoff sequence, this sequence allow second circuit search one by one people's platform can set up the new central station of dedicated radio link with it very soon, the radio communication of keeping the central station that is electrically connected with current wireless by first circuit simultaneously is connected, if a guy's platform can be set up the new central station of dedicated radio link with it very soon, just set up a new dedicated radio link to pass through second circuit communication with this new central station, to be maintained to by the dedicated radio link of article one circuit simultaneously and set up good new dedicated radio link predetermined instant in the past, and, if there is not new central station, just keep current dedicated radio link state.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12945499 | 1999-05-11 | ||
| JP129454/1999 | 1999-05-11 | ||
| JP20537/2000 | 2000-01-28 | ||
| JP2000020537A JP3533353B2 (en) | 1999-05-11 | 2000-01-28 | Handover method in a mobile station for PHS |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB001074504A Division CN1175688C (en) | 1999-05-11 | 2000-05-11 | Trans-zone switchover method for pHS personal station |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1592485A true CN1592485A (en) | 2005-03-09 |
| CN100456877C CN100456877C (en) | 2009-01-28 |
Family
ID=26464829
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB001074504A Expired - Lifetime CN1175688C (en) | 1999-05-11 | 2000-05-11 | Trans-zone switchover method for pHS personal station |
| CNB2004100786699A Expired - Lifetime CN100456877C (en) | 1999-05-11 | 2000-05-11 | Trans-zone switchover method for phs personal station |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB001074504A Expired - Lifetime CN1175688C (en) | 1999-05-11 | 2000-05-11 | Trans-zone switchover method for pHS personal station |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP3533353B2 (en) |
| CN (2) | CN1175688C (en) |
| HK (1) | HK1076000A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101523949B (en) * | 2006-10-03 | 2012-08-29 | 株式会社Ntt都科摩 | Cell/carrier switching and switching back upon rrc connection |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE60209090T2 (en) * | 2001-10-11 | 2006-08-03 | Matsushita Electric Industrial Co., Ltd., Kadoma | Passing on with fallback to the output communication channel in case of unsuccessful handover |
| KR101472197B1 (en) * | 2002-09-03 | 2014-12-11 | 인터디지탈 테크날러지 코포레이션 | A method and system for user initiated inter-device, inter-system, and inter-internet protocol address handoff |
| CN100426824C (en) * | 2004-03-26 | 2008-10-15 | 中兴通讯股份有限公司 | Method of carrying out intelligent service of personal portable telephone system |
| US8406222B2 (en) * | 2004-07-30 | 2013-03-26 | Sharp Kabushiki Kaisha | Control system of communication network |
| KR100946878B1 (en) | 2005-01-10 | 2010-03-09 | 삼성전자주식회사 | System and method for allocating a channel quality information channel in a communication system |
| CN100463562C (en) * | 2005-01-19 | 2009-02-18 | 中兴通讯股份有限公司 | Method of switching between base stations in personal handheld telephone system |
| CN100393172C (en) * | 2005-01-19 | 2008-06-04 | 中兴通讯股份有限公司 | Method of seamless switching for mobile telephones in personal handheld telephone system |
| CN101217815B (en) * | 2008-01-04 | 2010-09-01 | 北京北方烽火科技有限公司 | A cross-regional shifting method of traveling carriage initiative mobile communication system |
| CN101217814B (en) * | 2008-01-11 | 2011-03-23 | 展讯通信（上海）有限公司 | An improvement method for mission success rate of mobile terminal |
| JP2009267878A (en) * | 2008-04-25 | 2009-11-12 | Kyocera Corp | Radio communication system, radio terminal, and radio communication method |
| JP4730452B2 (en) * | 2009-03-31 | 2011-07-20 | ブラザー工業株式会社 | Image transmission system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6108322A (en) * | 1996-06-28 | 2000-08-22 | Motorola, Inc. | Method of enabling handoff |
| WO1998009454A1 (en) * | 1996-08-26 | 1998-03-05 | Motorola Inc. | Communication system with zero handover mute |
| JPH10271553A (en) * | 1997-03-25 | 1998-10-09 | Pioneer Electron Corp | Radio telephone system |
-
2000
- 2000-01-28 JP JP2000020537A patent/JP3533353B2/en not_active Expired - Fee Related
- 2000-05-11 CN CNB001074504A patent/CN1175688C/en not_active Expired - Lifetime
- 2000-05-11 CN CNB2004100786699A patent/CN100456877C/en not_active Expired - Lifetime
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2005
- 2005-09-07 HK HK05107857.2A patent/HK1076000A1/en not_active IP Right Cessation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101523949B (en) * | 2006-10-03 | 2012-08-29 | 株式会社Ntt都科摩 | Cell/carrier switching and switching back upon rrc connection |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3533353B2 (en) | 2004-05-31 |
| JP2001028776A (en) | 2001-01-30 |
| CN1175688C (en) | 2004-11-10 |
| CN100456877C (en) | 2009-01-28 |
| HK1076000A1 (en) | 2005-12-30 |
| CN1273497A (en) | 2000-11-15 |
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