The application is that application number is 02814051.6, the applying date is on June 13rd, 2002, denomination of invention is divided an application for the patent application of " repeatedly surveying heartbeat signal to reduce the probability of error ".
Embodiment
Be explanation below to the preferred embodiment of the present invention.
Leak the heartbeat signal (HB/RQST) of surveying or surveying heartbeat signal (HB) by mistake and be with request to start working and to pay very big cost.If mistake has been surveyed HB,, can be created on power control command and the time control command used between base station and the field terminal then according to the incorrect code phase of connecing reception.Therefore, power control is exactly incorrect, and is not based on from the power of terminal actual reception.For request message, then when not needing resource to user resource allocation, thereby cause the capacity wasted.
Way routinely is if low-down mistake detection probability is very important, just require at base transceiver station (BTS) very high Eb/No (being every potential energy and noise density) threshold value to be set.As another kind of situation, if speed of detection is not so important, then for the HB signal, repeatedly continuous probe can be useful.The mistake detection probability is reduced greatly.
For example, if P (fd) if=0.01 and specify in definite " effectively survey " and in delegation, carry out three times before and survey then overall P (fd)=0.01^3 or 0.000001.For detection, the cost of doing like this is very little, because the probability of beginning is very high.For example,, need three detections will monitor probability and be reduced to 0.9^3 or 0.72, just slightly descend if single monitoring probability is 0.9.This technical method is very common in radar system, but in the application who is used for surveying HB and HB/RQST signal, and do not use as yet in other communication systems and the application.Should be understood as the example of the content that can use the present invention's instruction to HB and HB/RQST signal, and should not become from any angle limitation of the present invention.
The signal of surveying and counting (i) for example, can be continuous, no matter in time, still press user's distributed time slot in the tdma system, the interval perhaps (ii) can be arranged between signal, but in the given time interval, have pulse, position or other indications to determined number.For a CDMA reverse link, can be requiring a plurality of continuous monitorings or discontinuous monitoring as system-level detection.In addition, system can also be provided with different a power controlled target and a detection of a target, this means for lower through-put power, will increase the time of integration to improve the monitoring energy.For the system that uses time slot, system can comprise the intelligence of the continuous or discontinuous time slot that monitors given user.In addition, system can also handle gating and non-gating signal.
The annoyance level of heartbeat signal derives from a typical radar monitoring problem.For this reason, for Dedicated Control Channel in the CDMA technology (DCCH) and time slot control maintenance pattern (DCHM),, and various advantages are achieved based on quilt " detection " rather than by the heartbeat pulse of demodulation.
Fig. 1 is communication system 100 schematic diagrames as example.This system is the same with said system, has used one embodiment of the present of invention.As shown in the figure, the base transceiver station 25 of band antenna tower 23 keeps wireless communication link with 42a, 42b, each field unit of 42c (being combined into field unit 42).These wireless links are to set up on the basis of Resources allocation on forward link 70 between base station 25 and the field unit 42 and the reverse link 65.Every link 65 or 70 generally is made up of several logic reversal link channels 55 and several logic forward link 60 channels respectively.
As shown in the figure, communication system 100 support connect 50 and network 20 between radio communication.Network 20 generally is public switch telephone network (PSTN) or computer network, as internet or Intranet.In the preferred case, connect 50 and digital processing units, for example a portable computer 12 is also referred to as addressed location sometimes and connects, so that the accessing wirelessly to network 20 is provided.Therefore, portable computer 12 can be on the communication infrastructure that wired and wireless data link combines accesses network 20.
In a preferred embodiment, forward link 60 and reverse link 55 are defined as CDMA(Code Division Multiple Access) (CDMA) channel in communication system 100.Be that every CDMA Channel is by encoding and transfer of data on this channel with increasing letter pseudo noise (PN) code sequence by priority definition.Then, the PN coded data is modulated onto on the radio frequency carrier.As long as the specific letter PN code that increases that this just makes receiver know to distribute to particular channel just can make a distinction a CDMA Channel and another channel.According to an embodiment, under the preferable case, every channel can take the wave band of 1.25 megahertzes that meet IS-95 CDMA standard or 1xEV-DV standard, and can transmit with 38.4k bps speed.
Article one, forward link 70 comprises 4 logic forward link channels 60 at least.As shown in the figure, it comprises the channel 60PL that pilots, link-quality management (LQM) channel 60L, paging channel 60PG and multiplexing channel 60T.
Article one, reverse link 65 comprises 5 logic channels 55 at least.As shown in the figure, it comprises heartbeat standby channel 55HS, heartbeat request working channel 55HRA, access channel 55A and multiplexing channel 55T.In general, can support that except that every inbound transmission link channel 60T reverse chain channel 55 is identical with forward link channels 60 from 2.4 to maximum 160k bps various data transmission rates.
Data packets for transmission is drawn together encoded digital information between base station 25 and field unit 42a, for example web data.Based on the distribution of multiplexing channel in reverse link 65 or forward link 70, the particular link between base station 25 and field unit 42a can reach higher data transmission rate.Yet because a plurality of field unit 42 contention allocated bandwidth, a field unit 42a must wait for, until there being idling-resource can distribute to transmission channel to send the data payload.
Be used to distinguish in argumentation heartbeat signal and band request heartbeat signal exemplary detector system (Fig. 2) before, with reference to Fig. 3 A-3C type signal is done one earlier and briefly introduces.
In Fig. 3 A, one can have 3 kinds of different states by the 1xEV-DV signal 160 that field unit sends: " control keeps " state 165, " request is started working " state 170 and data transmission state 175.At " control keeps " state 165, signal 160 does not conform to the indication of " request is started working ".In other words, signal 160 keeps " leaving unused " or " control keeps " state, and this expression field unit 42a does not ask transmission channel." request is started working " state 170 shows that field unit asking the data transmission channel by reverse link to send data to BTS 25.At data transmission state 175, communication data sends to BTS by field unit.Communication data has carried out transmission by reverse link after, send " transfer of data is finished " state (not marking among the figure) earlier, signal 160 returns to " control keeps " state then.
Though signal 160 marks as individual signals, it should be interpreted as a plurality of signals, can its coding be entered the channel of mutual exclusion with quadrature or non-orthogonal code selectively.For example, " control keeps " state 165 can transmit by a passage that is different from " request is started working " state 170.Equally, also can be at the communication data of data transmission state 175 transmission a channel that is independent of other two states 165,170.The multichannel example is discussed with reference to Fig. 3 B and 3C.
Fig. 3 B is internet CDMA(Code Division Multiple Access) (I-CDMA) signal graph as example.This figure gives user 1,2,3......N with time slot allocation, and repeats the distribution of time slot in epoch section i177a, i+1 177b etc.Channel is made up of heartbeat channel 55H, request channel 55R and transmission channel 55T.Every channel in these three channels all has code C1, C2, C3, a C4......CN who is associated, and signal can be transmitted by the encoding channel of mutual exclusion.Transmission and receiving system are utilized code to distinguish the interior information of channel respectively, thereby the information in the channel are handled all with the typical C dma mode.
As shown in the figure, exist signal 180 to show in heartbeat channel 55H, user 1,2,4,5,6......n are asking to keep idle state.User 3 then based on a signal 185b and possible other times section in the request channel 55R among a signal 185a, the second time period 177b in the request channel 55R among the very first time section 177a, is asking by rl transmission data.In the 3rd time period 177c, BTS 25 detects the request of transmission data based on two continuous indication 185a and 185b.After receiving the confirmation, user's 3 beginnings send communication data 190 in a relevant transmission channel that uses code C5.In another embodiment, BTS can require 3 continuous indication 185a to 185c before determining to have made request and this request carried out confirming.
Fig. 3 C is the more detailed signal graph of 1xEV-DV signal among Fig. 3 A, is used to indicate " request is started working " made to the base station from field unit 42a.In the present embodiment, the 1xEV-DV signal is made up of a plurality of signals that are on the Different Logic channel, that is: heartbeat channel 55H and request channel 55R.Heartbeat channel 55H constantly provides regularly and out of Memory (for example power stage, synchronous etc.) to base station 25 from field unit 42a.Field unit 42a utilizes request channel 55R to make request (for example numerical digit " 1 ") to base station 25, transmits data with request on a channel on the reverse link 65.
Sampling time 195a, 195b......195f (being combined as 195) the indication BTS25 that represents with arrow carries out time of request signal 55R time slot sampling or at interval, and alternatively, and heartbeat channel 55H determines the request of transmission channel well afoot whether.Be noted that sampling can carry out in the subclass of whole time slot or time slot.And at the code of this specific embodiment center hop channel 55H and request channel 55R use mutual exclusion, therefore, sampling is on the Code Channel 55H and 55R of mutual exclusion, carries out in the subclass of all time slots or time slot.In a certain embodiments, for example in 195b, 195d and the time slot in 195f sampling time, sample to Code Channel 55H, the 55R of mutual exclusion in branch is used in the time slot of request indication in base station 25.In these time slots, heartbeat channel 55H " does not work ", and request channel 55R is " in running order " then.
As mentioned above, the signal in the request time slot of " in running order " can be a modulation intelligence, also can just not have the pilot signal of the coding of " numerical digit ".Like this, only just survey heartbeat signal with heartbeat signal and band request a particular time interval or in a plurality of time interval, corresponding energy level be basic in the corresponding time slot.
In a particular embodiment, " control keeps " state 165 index signals have first energy level, and " request is started working " state 170 then has second energy level.Base station 25 can also utilize the difference in the power levels except the pulse that is recycled and reused for indication request and starts working.For example, in this specific embodiment, distinguish this two states as long as measuring-signal (s), and accomplish that (i) makes comparisons energy level and at least one threshold value, perhaps (ii) alternatively, in the Code Channel of mutual exclusion, in heartbeat signal is in the time slot of logical zero, defines a request and exist.The different energy levels of index signal are provided by the occupation efficiency of signal, frequency, power and signal transmission structure etc.
For the energy level of understanding signal is how to be used for improving systematic function, we can consult Fig. 4, this figure is a width of cloth curve chart, explanation is selected request signal transmission according to following parameter or factor: (i) detection probability P (d) (x-axle), (ii) the signal to noise ratio of representing with decibel (y-axle) is (iii) surveyed probability P (fd) (curve among the figure) by mistake.This chart understands that the needed signal to noise ratio of line rectification detector input terminal as the function of individual pulse detection probability, is surveyed probability P (fd) then as a parameter by mistake in order to calculate a non-fluctuating signal.Should point out, can select for use different parameters or factor to set up or the transmission power level of definite index signal.
At delineation point 200, signal to noise ratio is 3dB, P (d)=20%, P (fd)=1%.Improve detection probability in order to survey under the constant situation of probability in mistake, as long as will draw a circle to approve a little 200 surveys probability curve along same mistake and upwards slides, this means that the raising of signal to noise ratio is used to improve the performance of system, thereby also strengthened the possibility that request signal is detected very soon.
Before a prominent example being provided and the energy level of typical heartbeat standby 55HS used as the communication system 100 (Fig. 1) of example and heartbeat request work 55HRA discussed, processor and the detection system that may use this system are earlier now carried out concise and to the point discussion.
Fig. 2 A is the schematic diagram of a width of cloth request detection processor 110, and this processor is used for determining whether field unit 42a asks to send data to BTS 25.Receiver Rx 35 received signals 55, these signals comprise maintenance channel 55M, transmission channel 55T, access channel 55A, heartbeat standby channel 55HS and heartbeat request working channel 55HRA.Signal 55 is handled, made heartbeat channel processor 112 receive heartbeat standby channel 55HS, request channel processor 114 then receives heartbeat request working channel 55HRA.
Heartbeat channel processor 112 contains identical processing unit with request channel processor 114, so in this specific embodiment, only heartbeat channel processor 112 is made a brief description.
Heartbeat channel processor 112 receives heartbeat standby channel 55HS.Correlator 115 uses a despreader 120 to carry out the despreading of heartbeat standby channel 55HS.Integrator 125 is used for coherent manner combination heartbeat signal.By the coherent combination of signal, the integration of I, Q and phase place thereof causes the output of moving of signal phase and signal power.
After correlator 115, rectifier 130 (be signal square absolute value) is adjusted signal power, carries out integration by second integrator 135 then, is received the energy of heartbeat signal with calculating.Second integrator 135 provides the incoherent combination of signal, and finishes calculating in the very short time interval.If moving velocity of terminal is too fast, non-coherent integration only provides amplitude, thereby causes the overlapping of 180 degree phase points, and this can cause in the ambiguity that does not have to determine under the situation of incoherent combination signal energy.
What heartbeat channel processor 112 was exported is a heartbeat energy level, and 114 outputs of request channel processor is a request energy level.In the present embodiment, each energy level all feeds back to hypothesis detector 140, determines by this detector whether heartbeat signal, request signal are in the reverse chain channel 55 that is received by base station 25, and perhaps both are not all not within it.
The output of supposing detector 140 is provided for state machine.This state machine is used for determining whether field unit makes " request is started working " according to given standard, and in a certain embodiments, this standard is the measurement result to the hypothesis detector.For instance, measurement result comprises to be counted the quantity of continuous request signal, measures the start working ratio of channel signal of heartbeat standby channel signal and heartbeat request, counts or the like for the signal of starting working of the heartbeat request in the preset time scope.And, suppose that the difference of energy level in detector 140 and the indication information has been improved systematic function, though this not required for the present invention wanting.In other words, can be directly handle heartbeat standby channel 55HS and the heartbeat request channel 55HRA that starts working, to determine whether field unit 42a is asking to start working by state machine 145.After describing, an embodiment to state machine 145 will be described in more detail.
In a certain embodiments, boolean's true or false signal of state machine 145 outputs.Example by the process of state machine execution has been described in Fig. 2 B.
Fig. 2 B for example understands the flow chart of a state machine 145.When detection processor 110 " guiding ", this example state machine 145 begins in step 205.In step 210, state machine 145 starts the counter that has been used to determine whether to take place detection.In step 215, state machine 145 receives the output of hypothesis detector 140.After guiding, in a single day state machine 145 receives any output from hypothesis detector 140, just can be in step 215 beginning, as one " Interrupt Service Routine ".As mentioned below, when having determined detection or non-detection, counter is cleared (promptly being set to zero), the replacement measuring process so that need not to guide again detection processor 110.
Received the output from hypothesis detector 140 in step 215 after, state machine 145 determines whether the output of hypothesis detector 145 is a request (i.e. " request is started working ").If then state machine continues in step 240, probation counter increases in this step.In step 245, explorer count device and a threshold value are compared.If the explorer count device surpasses this threshold value, then in step 250, state machine 145 reports detect from field unit 42a has made " request is started working " request.If probation counter does not surpass this threshold value, then state machine 145 turns back to step 215, and waits for another output that receives from hypothesis detector 140.
Then with reference to Fig. 2 B, if in step 220, determine that the output from hypothesis detector 140 is not one " request ", then this state machine 145 proceeds to step 225.In step 225, state machine 145 increases non-probation counter.In step 230, determine whether non-probation counter surpasses a threshold value.If then state machine 145 proceeds to step 235, do not detect " request is started working " that field unit 42a makes in these step state machine 145 reports.Do not surpass threshold value if detect counter, then state machine 145 proceeds to step 215.
After step 235 and 250, state machine 145 is removed counter in step 255, and enable state machine 145 is surveyed " request is started working " in the future of being made by field unit 42a.In step 260, state machine 145 finishes.
State machine 145 uses probation counter to determine that according to a given standard probation counter 110 has received the indication of what " request is started working ".This standard can be any form, comprises given continuous probe number of times, the interior given detection times of section preset time, or the ratio of surveying and not detecting.As alternative, can use based on the non-counting of measuring to determine whether to make the request of starting working, such as the phase place of measuring request signal.
Should be appreciated that state machine 145 can use the alternative of utilizing counter or other standards.For example, state machine 145 can use other handling processes, and non-counter variable or other are determined the standard or the non-standard technology of detection.And, except receiving the output, can be from heartbeat channel processor 112 or ask the initial data of channel processor 114 to the input of state machine 145 from hypothesis detector 140.And in a further embodiment, state machine 145 can be combined with hypothesis detector 140 and be included in wherein.
2A with the aid of pictures again is except user mode machine 145 guarantees that whether survey field unit 42a with very high probability makes " request is started working ", has also used hypothesis detector 140.
For determining to have occurred which or which signal, suppose that detector 140 contains logic function.For example, in this specific embodiment, suppose that detector 140 compares the first energy level threshold value with first energy level (being the heartbeat energy level), and the second energy level threshold value is compared with second energy level (promptly asking energy level).
Heartbeat energy level and request energy level energy level threshold value by comparison are respectively 9dB and 11dB.The energy level threshold value can be selected, pre-determine in dynamic ground, also can otherwise use, and for example, based on the power stage of a transmission, this power stage can be reported to the base station by heartbeat channel 55H by field unit.When carrying out energy level calculating and comparing, first and second energy levels may be decided according to the occupied situation of time slot in the used signal transmission passage of signal 55, for this reason, the bit number of energy level threshold value numeral " 1 " can an expectation or regulation be the basis, and this bit number is used for expression " request is started working " or expression request maintenance idle condition.The invention people who submits simultaneously with the application is Proctor, J, in the relevant U. S. application of denomination of invention for " Transmittal of Heartbeat Signal at a Lower Than HeartbeatRequest (transmitting heartbeat signal) " than heartbeat request with lacking, the use of energy level threshold value has been discussed, and wherein disclosed content is quoted in this article to do reference.
As mentioned above, the output of measuring hypothesis detectors 140 by state machine 145 is to determine whether to change the state of communication system, and this state is the state of the reverse link communications channels between field unit 42a and the base station 25.For example, determine that field unit 42a makes " request is started working " (promptly sending transfer of data on reverse link) if suppose detector 140, then the processor (not shown) of state machine 145 in BTS 25 exported a signal, and this BTS 25 is responsible for pocket computer 12 a communication channel 55T is provided.In a particular embodiment, if determine that continuously the quantity of continuous request signal is 2 or a plurality of, BTS 25 allocation of communication channels 55T then.Selectable standard is above discussed.
As the elaboration that reference Fig. 3 C is done, the configuration of heartbeat channel processor 112, request channel processor 114 and hypothesis detector 140 and design can make the monitoring of time slot and take the request that changes communications status that is used to represent.In one embodiment, shown in Fig. 3 B and 3C, detection comprises that the Code Channel to mutual exclusion takies the monitoring of situation.
A feedback loop (not marking) is used to cause heartbeat channel processor 112 and request channel processor 114 to have " self adaptation " ability.For example, can adjust the time of integration of integrator 125,135 according to the received energy level of heartbeat channel 55H, and be used for also can being fed the loop adjustment with heartbeat and the energy level threshold value that the request energy level compares by hypothesis detector 140.The quantity that other feedback can cause (i) to survey needed continuous impulse increases or reduces, or the quantity of the request signal that (ii) transmits increases or reduces.This feedback loop can use an instruction or information, and transmission information between BTS and field unit, these information comprise pulse repetition or the power stage about the heartbeat signal of heartbeat that is sent by field unit 42a and band request.
As mentioned above, first communications status may be the standby communication state, and the second communication state may be the payload communications status.In other system or even same system, communications status can also refer to other communications status, and for example, request changes base station, power control signal transmission state etc.The method of different energy levels of using in signal transmits described herein is applicable to wired, wireless or optical communication system.In either case, communications status can use in speech or data communication system.
And for example with reference to the elaboration that Fig. 4 did, second energy level can one acquisition probability, mistake survey the basis that is combined into of probability or two kinds of probability.In other words, field unit can be with specific power stage, or the mode that sends the pulse of specific quantity in certain period of time sends request signal, recently guarantee a specific acquisition probability, false failure rate to reach corresponding noise, perhaps both, as the front with reference to elaboration that Fig. 4 did.
Can use a kind of analytical method to set the index signal quantity of through-put power or transmission, perhaps in communication system, use the feedback mechanism of above discussing to cause field apparatus to change its behavior, thereby make the index signal energy level that receives reach a predetermined signal to noise ratio, therefore can provide needed detection probability and false failure rate parameter.
Simulation
Now carry out once supposing wherein that about the simulation of backward chaining this backward chaining has the various exemplary types as shown in Fig. 3 A-3C, or the power control and the heartbeat channel of the transmission of the communications link signals of other type.
Two kinds of hypothesis are set up in simulation at first, for this reason.The first, power is controlled at the path of being surveyed or uses in the combination in single path.Just survey even without acquisition, also carry out power control.The second, detection probability is set so that realize surveying, thereby guarantees on correct signal, to carry out power control with sufficiently high detectivity.Clearer and more definite, need survey the signal that receives to follow the tracks of.
Table 1 is depicted as the vehicle that sails out of the base station for the speed of 60 miles per hours, the needed detectivity of single path channel.Because motion, this table need whenever have the conversion of a section just at least once to survey.
The transformed distances of 1 section |
814 |
Foot |
Mobile phone speed |
60 |
Miles per hour |
Mobile phone speed |
88 |
Feet per second |
The section transformation rate |
9.2 |
Section/second |
HR Heart Rate |
50 |
Heartbeat/second |
Heartbeat/Td |
462 |
|
Table 1
In table 1, time period Td is defined as such time period, must survey to guarantee the motion owing to vehicle, along with this signal is followed the tracks of in the conversion of time of arrival (toa) single heartbeat pulse on this time period.Table 1 expression must receive in per 462 pulses with very high probability, otherwise the danger that loses the tracking of signal is just arranged.
Based on this calculating, detection threshold is set according to detection/mistake detection probability table (as Fig. 4).Though table 1 is additive white Gaussian noise (AWGN) definition, estimate that these detection probabilities can not be subjected to big influence on the short relatively time.This is because the statistics independence of the decay from the heartbeat pulse to the heartbeat pulse.
Though difference is very big between the detection of single pulse probability, from overall result, this difference can not surpass about 50% at the coefficient of surveying on the stand-by period.Particularly, the average detection delay time of request message is compared with 30 kilometers/hour about 15 milliseconds among the AWGN, is 11 milliseconds.Repeat, what the reason that produces this result need to be is a detection process rather than the demodulating process that difficulty is high.
Based on this analysis, 20% detection probability and 1% mistake detection probability have been selected.This requires average Eb/No is 3 decibels.In Fig. 4, this is illustrated and discusses.
Table 2 is depicted as at the detection probability that time T d calculated of afore mentioned rules and mistake detection probability.
Target E/Io (gross energy/interference density) |
3dB |
Detection probability |
0.2 |
The mistake detection probability |
0.01 |
Detection probability for 3 successive heartbeats |
8.00E-03 |
Test number (TN) among the Td |
462 |
No detection probability among the Td |
2.44E-02 |
3 continuous mistake detection probabilities |
1.00E-06 |
The errorless detection test that needs |
462 |
Mistake detection probability for Td |
4.62E-04 |
Table 2
In order to reduce the mistake detection probability, need 3 continuous detections to verify a single detection.Because detection probability obtains by multiplication in this case by mistake, single mistake detection probability becomes cube.
Following table 3 has calculated the needed average Ec/Io of the statistics that obtains table 2 (energy/interference density of each section, this is the signal to noise ratio in whole section upper integral).
Target E/Io | 3 | Decibel |
Processing gain | 256 | |
Burst Ec/Io | -21.08 | Decibel |
Average Ec/Io | -40.9 | Decibel |
Table 3
Because the heartbeat channel has time division multiplexing (TDM) structure, the interference to every other user that is caused by heartbeat user increase is as follows:
Effectively average Ec/Io (all HB users)=10*log10 (N)-40.9, wherein N is a number of users.
Therefore, for 96 users of a given base station, average total interference will equal the Ec/Io that happens suddenly, just-21.08.
Though the utilization of the present invention reference relevant with preferred embodiment carried out special displaying and description, but, those skilled in the art understands, under the prerequisite that does not depart from invention scope included in the appended claims, may do various modifications in the form and details.