CN101478823B - Code division multiple access user facility - Google Patents
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Abstract
The invention relates to code division multiple access user equipment which can use a lower error detecting mark because a field unit (55) sends marks (e.g a mark by 9dB, and another mark by 11dB) in different power levels. The different power levels of the marks make a base station (110) capable of using selectable standards to recognize a request mark in a low error probability. And the selectable standards can comprise marking the comparison with each power level threshold value, the monitoring of time slot occupation situation, the occupation situation of mutex code channels or the combination of all of the factors. For example, in a special embodiment, a request mark is usually a high priority mark and is sent in a higher power so that the detection probability is improved and the error detection probability of the request mark is reduced.
Description
The application is that the application number submitted on June 13rd, 2002 is 02814052.4, name is called the dividing an application of Chinese patent application of " carrying out the heartbeat signal transmission with the energy level that is lower than heartbeat request ".
Background technology
The use of radio telephone and personal computer is increasing, and causing constantly increases the demand of advanced communication service.And this service in the past only once was counted as to special application and provided.In the eighties in 20th century, wireless voice communication is popularized by cellular phone network.Because people estimate that customer charge can be very high, so think from the beginning, this service specially is object with the business people.Like this too aspect the visit of long-distance distribution formula computer network.Just not long ago, also have only business people and big mechanism just to afford to use needed computer and wired access means.
Along with the new technology that people afford to use is popularized, common people no longer are satisfied with networks such as wired mode access the Internet and private intranet, also wish to conduct interviews with wireless mode.Wireless technology does not want to be subjected to the user of equipment such as portable computer, laptop computer, handheld digital assistant of telephone wire constraint particularly useful for those.
Use existing wireless infrastructure, go back generally feasible, gratifying way of neither one at present, accomplish the low cost of internet, private intranet and other network, high-speed visit.This is likely what some unluckily situations caused.At first, in business environment by cable network provide the typical way of high-speed data service can not be at an easy rate with most of families or office can with the voice grade service adapt.For example, the high-speed data service of this standard differs and transmits information by standard cellular radio telephone handset surely not yet in effectly, because being design at first, wireless network is used for a transporting speech, although some system, as cdma system, really the working method that can adopt some to have asymmetric nature is carried out transfer of data, for example, telecommunications industry association (TIA) for the forward traffic channel data rate of IS-95 system regulation is: speed group 1, can carry out incremental adjustments from 1.2k bps to 9.6k bps; Speed group 2 can be carried out incremental adjustments from 1.8k bps to 14.4k bps.Yet the data rate of reverse link traffic channel is fixed on 4.8k bps.
Therefore, under best situation, existing wireless system generally only provides a radio channel, and the maximum data rate on the forward link direction can reach per second 14.4k bps.So the channel of low speed can't directly be used for coming transmission information according to the 28.8k that generally uses at present even the speed of 56.6k bps cheap wire line MODEM, has let alone according to 128k bps that can reach such as Integrated Service Digital Network(ISDN) (ISDN) equipment higher like this speed.Above-mentioned these data rates will become movable receptible minimum speed limits such as browsing page soon.
Although when cellular system is just developed, cable network is known, but people in most of the cases do not take measures, in order to make this wireless system provide more at a high speed ISDN or ADSL level data to serve by the cellular network structure.
In most of wireless systems, potential user is more much more than radio channel resource.So need certain based on the multiaccess system of demand.
No matter multiple access is by providing by traditional frequency division multiple access (FDMA) technology of one group of radio-frequency carrier signal being carried out analog-modulated, still be by utilizing time-division multiple access (TDMA) to realize in the mode of the frequency of a shared carrier signal, or realize that by the CDMA(Code Division Multiple Access) mode radio-frequency spectrum all has the characteristics that will be shared.This is very different with the traditional environment of supporting transfer of data.Wire medium relative low price under this environment, and generally do not prepare to share.
The other factors that will take in the design of wireless system is the characteristic of data itself.For example, should be taken into account that the visit to webpage generally is towards paroxysmal, need carry out the transfer of data of asymmetric speed in reverse and direction.Common way is at first to be stipulated the address of a webpage for browser program by a remote client computer user.With this address, length is generally 100 bytes or shorter to browser program by network then, sends to a server computer.This server computer uses the web page contents of asking to give to answer then.Its content can be text, image, the audio or video data from the 10k byte to the number Mbytes.After this, the user may read web page contents with the time of several seconds even a few minutes, and then downloads another webpage.
Under office environment, most of employees use the custom of computer operation, generally are to check several webpages earlier, do some other things then in long time period, as the local data that store of access, even stop using computer fully.Therefore, even these users are connected on internet or the private intranet all day always, the actual use of high-speed data chain generally is very incoherent.
If support wireless data transfer services and wireless voice communication coexistence that the internet connects, the use of then optimizing available resources in the radio CDMA communications system just becomes more and more important.The recycling of frequency and dynamic service channel allocation relate to some aspect that strengthens high-performance radio CDMA communications system usefulness, still, still need more effectively to utilize existing resource now.
Summary of the invention
In one application, one is marked at and transmits by a channel in the time slot, shows that a corresponding field unit has sent the request of starting working.Namely be marked in the time slot of an appointment and transmit, show that field unit sends request, require to distribute reverse link traffic channel to the user, in order to send the data payload from field unit to the base station.This explanation field unit is in holding state at present.Conversely, field unit shows then that by another channel transmission mark in a pair of reverse chain channel field unit does not have request to start working.For example, existing, a unit is not want to keep synchronously with the base station but request keeps off position, in order to change operating state at any time rapidly again over to by reverse chain channel transmission data.
In either case, use the wireless communication system of the principle of the invention, owing to send mark (for example use 9dB for, another uses 11dB) with different power levels, can improve the detection performance to mark, thereby improved the performance of system.The power level difference of mark makes the base station can use selectable standard with the unidentified request marks of the very low probability of error, herein selectable standard can comprise with mark and separately power level (power level) threshold ratio, the situation that takies of the Code Channel of the situation that takies of monitoring time slot and mutual exclusion, or both comprehensive conditions.For example, in one embodiment, a request marks, normal priority is higher, with higher power level transmission, can improve detection probability and reduction the mistake of request marks is surveyed probability.
In the application example of a specific cdma system, field unit provides the heartbeat channel (HB/RQST) of unite as one jumping (HB) channel and a strip requests.(HB) channel is first code what use in the reverse link of base station, is second code and the HB/RQST channel uses in reverse link.In this CDMA application example, according to principle of the present invention, field unit can send HB and HB/RQST channel with different power levels.Give HB/RQST higher power in the preferred case, because it is a kind of high priority signals.
The invention discloses a kind of field unit, this field unit comprises: antenna; The code division multiple access transceiver; Described field unit is configured to the basis foundation of Resources allocation on forward link and reverse link and the wireless connections of base station; Described field unit further is configured to send the existence indication by described reverse link to described base station from described field unit, and sends request to ask to keep reverse link traffic channel from described field unit distributed time slot by described reverse link.
Content disclosed by the invention is supported I-CDMA and lxEV-DV system, but is enough to support those to use the system of various other communication protocols of using in wired and the wireless communication system usually.CDMA(Code Division Multiple Access) system (CDMA), as IS-2000, and Orthodoxy Frequency Division Multiplex (OFDM) system, as IEEE 802.11a WLAN (wireless local area network), can use embodiments of the invention.
Description of drawings
Foregoing and other target of the present invention, characteristics and advantage will become more clear by the more specifically description of preferred embodiment being carried out below in conjunction with accompanying drawing.In different accompanying drawings same with identical width of cloth figure mark indication.Owing to more pay attention to explanation of the principles of the present invention, so accompanying drawing not necessarily meets ratio.
Fig. 1 is a width of cloth communication system schematic diagram, and the embodiment of the invention will be launched in this system;
Fig. 2 is a width of cloth schematic diagram, introduces base station employed subsystem in the communication system of Fig. 1, and this subsystem is used for determining whether a reverse link signal contains the request indication that with good grounds signal power level changes communications status;
Fig. 3 A is the signal graph of a width of cloth lxEV-DV system, and first mark is represented " control keeps " among the figure, and second mark is represented " request is started working ";
Fig. 3 B is CDMA(Code Division Multiple Access) (CDMA) collection of a width of cloth Code Channel, and a mark is arranged in a distributed time slot, represents that a field unit asking to change communications status;
Fig. 3 C is a selectable reverse link signal embodiment signal graph that has indication;
Fig. 4 is a width of cloth signal to noise ratio and detection probability correlation curve figure, can be used for determining the power level of the interior indication of signal among Fig. 3 A-3C.
Embodiment
Be the explanation to the preferred embodiment of the present invention below.
In radio communication, the power that the preferred embodiments of the present invention are applied to send from mobile phone (or terminal base station (BTS) target received power), contrast with the heartbeat signal that carries out heartbeat signal (HB) and band request (HBR, HB/RQST, or directly be called " request " signal).HB and HB/RQST signal can disclose according to U.S. serial 09/775,305 by a maintenance channel transmission, and this channel is the solid size channel (rather than multiple code channel) on the cdma communication system reverse link.Maintenance channel is the channel that is divided into time slot, and different user is dispensed on the different time slots.
Field unit in the wireless communication system sends a heartbeat signal and controls to keep timing and/or power, and has indication to the BTS transmission.When a terminal needs the reverse chain channel of a distribution, this terminal will send 1 request signal at least.This or these signal can be the information through ovennodulation, perhaps is exactly the pilot signal that does not have " numerical digit ".
The requirement that detection probability and the mistake of these channels are surveyed probability is very different.For example, relatively low to the detection probability of HB.Its detectivity only need be enough to follow the tracks of the timing conversion of the Code Channel that the physical motion of the multipath structural change that causes because of the Doppler effect in the channel causes.In this case, power control continues to be independent of detection or works under the situation that does not have detection.
For example, if surpass predetermined threshold value at the power that receives, and under the situation that correlation is mated, signal is not detected, and then power instruction is namely indicated, and power is too low, terminal necessary " increase power ".A requirement in this specific embodiment is that the generation frequency of detection should be enough to make detector can aim at received signals in time.
On the other hand, because request is a kind of emergency, request signal is regarded as the high priority signal, so, very high possibly to the detection probability of request signal.Therefore, request signal can send with higher power, and also can establish in a different manner directly in the threshold value of BTS.This will cause higher detection probability and lower mistake to survey probability.
Therefore, according to principle of the present invention, can use different detection probabilities and mistake to survey probability to heartbeat signal, request signal or any other signal message.
According to different signal types, an access terminal can send signal with different power.The request that BTS can use different standards to survey and send at signal is indicated.For example, in the Code Channel of the channel that is divided into time slot or mutual exclusion, some time slots are occupied when carrying out a request, rather than occupied when not asking.In this case, no matter higher power still exists, or both can be used as detection criterion simultaneously.
Fig. 1 be one as communication system 100 schematic diagrames of example.This system is the same with said system, has used one embodiment of the present of invention.As shown in the figure, the terminal base 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 that the basis of Resources allocation on the forward link 70 between base station 25 and the field unit 42 and reverse link 65 is set up.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, the radio communication between communication system 100 supporting interfaces 50 and the network 20.Network 20 generally is public switch telephone network (PSTN) or computer network, as internet, the Internet or Intranet.In the preferred case, interface 50 and a digital processing unit coupling, for example a portable computer 12 is also referred to as access means sometimes, in order to 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 every CDMA Channel by encoding and transmit and by priority definition at channel with pseudo noise (PN) code sequence of expansion.Then, the PN coded data is modulated to a radio frequency carrier.As long as the special expansion PN code 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, every channel can take the frequency band of 1.25 megahertzes that meet IS-95 CDMA standard and 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 60 PG and multichannel Traffic Channel 60T.
Article one, reverse link 65 comprises 5 logic reversal link channels 55 at least.As shown in the figure, it comprises heartbeat standby channel 55HS, heartbeat request working channel 55HRA, access channel 55A and multichannel Traffic Channel 55T.In general, except every reverse traffic link channel 60T can support that reverse chain channel 55 is identical with forward link channels 60 from 2.4 to maximum 160k bps variable-data-rate,
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 multichannel Traffic Channel in reverse link 65 and forward link 70, the special link between base station 25 and field unit 42a can reach higher data speed.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 Traffic Channel to send the data payload.
In the exemplary detector system (Fig. 2) of discussing the heartbeat signal that is used for differentiation heartbeat signal and band request before, briefly introduce with reference to the type signal work one of Fig. 3 A-3C earlier.
In Fig. 3 A, one can have 3 kinds of different states by the lxEV-DV signal 160 that field unit sends." control keeps " state 165, " request is started working " state 170 and data transmission state 165.At " control keeps " state 165, signal 160 does not contain 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 have the requested service channel." request is started working " state 170 shows that field unit asking the data traffic channels by reverse link to send data to BTS 25.At data transmission state 175, business datum sends to BTS by field unit.Transmit by reverse link in business datum, and after having sent " transfer of data is finished " state (not marking among the figure), signal 160 namely recovers " control keeps " state.
Though signal 160 marks as individual signals, it should be interpreted as a plurality of signals, can enter the channel of mutual exclusion with quadrature or non-orthogonal code coding selectively.For example, " control keeps " state 165 can transmit by different passages from " request is started working " state 170.
Equally, also can be independent of other two states 165,170 channel at one in the business datum of data transmission state 175 transmission.The multichannel example is not discussed with reference to Fig. 3 B and 3C.
Fig. 3 B be one as internet CDMA(Code Division Multiple Access) (I-CDMA) signal graph of example.This jail is given user 1,2,3 with time slot allocation ... N, and in epoch section i 177a, i+1 177b etc., repeat the distribution of time slot.Channel is made up of heartbeat channel 55H, request channel 55R and Traffic Channel 55T.Every channel in these three channels has code C1, C2, C3, a C4 who is associated ... CN can transmit signal 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 in typical CDMA mode.
As shown in the figure, in heartbeat channel 55H, exist signal 180 to show, user 1,2,4,5,6 ... n is asking to keep idle state.User 3 then based on a signal 185 in the request channel 55R among the very first time section i 177a, is asking by rl transmission data.In the second time period i 177b, user 3 begins to send business datum 190 with code 5 by a corresponding Traffic Channel.
Fig. 3 C is the more detailed signal graph of lxEV-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 25 provides regularly and out of Memory (for example power stage, synchronous etc.) to the base station from field unit 42a.Field unit 42a utilizes request channel 55R 25 to make request (for example numerical digit " 1 ") to the base station, transmits data to ask a channel on reverse link 65.
Cycle in sampling time 195a, 195b with the arrow indication ... 195f (being combined as 195) expression be that BTS25 carries out time of request signal 55R time slot sampling or at interval, heartbeat channel 55H also can determine during this period to the request of Traffic 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 " work " request time slot can be modulation intelligence, also can just not have the pilot signal 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, separately power level be basic in the time slot separately.In a particular embodiment, " control keeps " state 165 index signals have first power level, and " request is started working " state 170 then has second power level.
In this specific embodiment, distinguish this two states as long as measuring-signal (s), and accomplish that (i) makes comparisons power level and at least one threshold value, (ii) or determine in the Code Channel of mutual exclusion, in heartbeat signal is in the time slot of logical zero, there is a request to exist.The different capacity level of index signal is provided by the occupation efficiency of signal, frequency, power and signal transmission structure etc.
For the power 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%, and 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.
A prominent example is provided and to the communication system 100(Fig. 1 as example) before used typical heartbeat standby 55HS and the power level of heartbeat request work 55HRA discussed, processor and the detector that may use this system earlier now carried out concise and to the point discussion.
Fig. 2 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 receives signal 55, and these signals comprise maintenance channel 55N, Traffic Channel 55T, access channel 55A, heartbeat standby channel 55HS and heartbeat request working channel 55HRA.To the processing of reverse chain channel 55, make 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 information, the integration of I, Q and phase place thereof causes the movement of signal phase and the output of signal power.
After correlator 115, rectifier 130(is the absolute value of signal square) signal power is adjusted, carry out integration by second integral device 135 then, be received the power of heartbeat signal with calculating.Second integral device 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 power.
What heartbeat channel processor 112 was exported is a heartbeat power level, and 114 outputs of request channel processor is a request power level.In the present embodiment, each power level 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.
For determining to have occurred which or which signal, suppose that detector 140 contains logic function.For example, in the present embodiment, suppose that detector 140 compares the first power level threshold value with first power level (being the heartbeat power level), and the second power level threshold value is compared with second power level (namely asking power level).
" heartbeat " power level and request power level power level threshold value by comparison are respectively 9dB and 11dB.The power 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 power level calculating and comparing, first and second power 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 power 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.
Suppose that the output of detector 140 can be used to change the state of communication system.For example, if 140 determine, a field unit sends the signal (namely sending data at reverse link) of " request is started working ", suppose detector namely to signal of processor (not marking among the BTS 25) output, this processor then is responsible for providing a Traffic Channel 55T to portable computer 12.In one embodiment, be higher than the second power level threshold value if determine the signal power level that is detected, then by BTS 25 distribution service channel 55T.In addition, if hypothesis detector 140 determines that the power level that is detected is lower than the second power level threshold value, also distribution service channel 55T of BTS then.
As the elaboration that reference Fig. 3 C does, 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, integrator 125, time of integration of 135 can be adjusted according to the received power level of heartbeat channel 55H, and the power level threshold value that is used for comparing with heartbeat and request power level by hypothesis detector 140 also can be fed the loop adjustment.
This feedback loop can use an instruction or information, and transmission information between BTS and field unit, these information relate to the heartbeat that is sent by field unit or the power level of being with the heartbeat signal of 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 be called other communications status, and for example, request changes base station, power control signal transmission state etc.The method of different capacity level 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.
The elaboration of doing with reference to Fig. 4 and for example, second power level can a detection destination probability, the basis that is combined into that mistake is surveyed probability or two kinds of probability.In other words, field unit can be used specific power level, or the mode that sends the pulse of specific quantity in certain period of time sends request signal, recently guarantee specific destination probability, a false failure rate of surveying to reach corresponding noise, perhaps both, the elaboration of doing with reference to Fig. 4 as the front.
Can use a kind of analytical method to set the index signal quantity of through-put power or transmission, perhaps in communication system, use a kind of feedback mechanism to cause field apparatus to change its behavior, thereby make the index signal power level that receives reach a predetermined signal to noise ratio, therefore can provide needed detection probability and false failure rate parameter.
Simulation
What now introduce is simulation.What inquire into is to the detection probability of heartbeat (HB/RQST) channel of heartbeat (HB) or band request and the factor that false failure rate exerts an influence.Provided the signal to noise ratio (snr) target of heartbeat (HB/RQST) channel that is proposed to be used in heartbeat (HB) or band request.Also carried out analytical Calculation, to determine the target E/lo of suggestion, to guarantee acceptable detection probability and false failure rate.
In order to make reader understanding's simulation relevant with the control of IS-2000 power, should illustrate that following parameter has been used in current simulation to the reader:
800 hertz of closed power controls;
The computational methods of i user's SNR are SNR=P(i)-P_ interference+processing gain+Er, wherein P_ disturbs (i)=20*log 10(10) ^ ∑ j i(l0 ^P(j)/20)+10 ^(P
TH/ 20)), P(i wherein) be the power that receives from i user, P
THBe the minimum of thermal noise, and rigid 120 dBm that are set in;
Processing gain is 10 log64;
What attenuation model adopted is the Jakes model;
Er=with normally distributed random variable=0.67 dB of 1 sigma, be the SNR estimation error of BTS;
Power control bit (PCB) error=3%.
In this specific simulation, the selection of at first doing is to be HB channel select target SNR.On the basis of a 9dB E/lo, wherein E is the whole power in heartbeat message, has reached in additive white Gaussian noise (AWG) 95% detection probability and 0.1% false failure rate and (has seen Viterbi, A., CDMA: spread spectrum communication principle, Addison Wesley, 1995, P113).
Detection probability is brought up to 99% will be created in and be much higher than 1% false failure rate among the AWGN.This false failure rate is noticeable, because it can reach quite low level, to such an extent as to when terminal loses communication linkage with the base station, occur not having the phenomenon of detection in can be when relatively long.
In general, determined by a timer during this period of time that the no detection time in 500 milliseconds ~ 2 seconds is arranged, namely 25 ~ 100 continuous nothings are surveyed.As benchmark, in the single path of the 9dB E/lo decay environment, pre-determined 90% detection probability and 1% mistake in theory and surveyed probability.At this situation, the concrete condition relevant with detection probability in this decay environment considered in following argumentation.
Consider that now surveying next speed with field apparatus with the heartbeat signal of 50 hertz of power controls makes comparisons.Simulate at full speed the rate model for the basis, made some modifications in this model, for example, power control speed (PC) is 50 hertz, and standby terminal is divided time slot, zero lap etc.
Though it is unimportant that the speed of terminal surpasses about 2 miles per hours, it is useful that closed power control is considered to for allowing decay to change around average path loss.It should be noted that the result is not subjected to maximum to be about the influence of 40% power control bit (PCB) error rate basically.Surpass this limit, the system works situation is variation, the closed power control that needs certain form is described, to keep average path loss.So, carry out the closed power control of certain form, the control of the power of field unit conveyer (Tx) is being suitable for the mean value of field unit, to guarantee the average path loss for the base station, be of great use.
Use the simulation of above-mentioned parameter to show, if the base station to the detection of " request is started working " index signal than the low 2dB of target SNR (determined as the front), then on average detection time is about 16 milliseconds, standard deviation is about 14 milliseconds.Survey the stand-by period in order to reach lower HB/RQST, adopt according to the simulation knot, determined following equation:
Target _ SNR(RQST)=target _ SNR(HB)+2dB (1)
According to the detection/mistake that in QWGN, will the reach rate that tests the speed, for heartbeat message has been selected target _ SNR of 9dB, and be the band request heartbeat (HB/RQST) Information Selection target _ SNR of 11dB.The application of these parameters causes at speed 20 miles per hours, hangs down 15 milliseconds the average detection stand-by period under the condition of by mistake surveying probability.
Aspect wrong allocation probability, though in simulation, very clearly do not calculate false failure rate, the most pessimistic boundary below having provided:
Pfd（RQST）=（1 - Pd（HB））* Pfd（HB） （2）
= 5% * 0.1% = 5E - 5，
Wherein Pfd is false failure rate, and Pd is detection probability.
Above equation is from following two results that condition draws: (i) do not detect its existence when a HB occurs, (ii) detect HB mistakenly when a HB does not occur.This is a most pessimistic boundary, because the 2dB through-put power of extra HB/RQST not being Duoed than HB in analysis is included.
When the speed of HB was 50 hertz, this mistake that will average whenever produce a standby subscriber 400 seconds was distributed.For N heartbeat message user, this probability is linear, because event is mutually independently.Therefore for a specific base stations, the number of users in the time of at full capacity is 96, and estimated average mistake apportionment ratio is about 1 of per 4 second.
Because wrong distribution can be detected very soon, so wrong situation of distributing can obtain correcting faster.When mistake distributes now, generally can there be 3 kinds of situations.At first, the information transmission does not appear on the backward channel that distributes.Secondly, the heartbeat signal of band request does not occur.If the channel allocation of missing, then HB/RQST continues to occur.The 3rd, heartbeat message may occur.The probability of surveying less than this situation in a frame is Pdf(RQST)=5E-3%.This will be detected in one or two frames before channel can be redistributed to a validated user.If supposition is surveyed need carry out in 2 frames, then reverse capacity will only reduce 1% even still less, because the false failure rate target of HB/RQST is 11dB E/lo.
For a signal that between target _ SNR and detection threshold, does not have skew, be that the average detection delay time that the distant place user of 1 miles per hour and user that translational speed is 20 mph.s simulate is 35 milliseconds with translational speed.For the heartbeat signal of band request, the average detection delay time is less than 20 milliseconds, and detection threshold lacks 2dB than the 11dB of target SNR.This is possible, because the HB/RQST signal is than transmission (Tx) the power raising 2dB of HB signal.
Analog result shows, supposing in power control (PC) has 96 users in the cycle, and then minimum average B configuration time of delay is near 10 milliseconds.In 99% time, the predicted delay situation is better than 77 milliseconds.
Analog result also shows, the extra 2dB power that increases of HB/RQST signal transmission has improved detectivity and will survey the stand-by period and shortens to average 15 milliseconds.Estimate within few 6 dB of IS-2000 primary channel of the total interference ratio of cochannel (9600 bps reverse traffic channels (R-TCH), 9600 bps Reverse Dedicated Control Channels (R-DCCH)) of a full load maintenance channel.
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 model state included in the appended claims, may do various modifications in the form and details.
Claims (6)
1. field unit, this field unit comprises:
Antenna;
The code division multiple access transceiver;
Described field unit is configured to the basis foundation of Resources allocation on forward link and reverse link and the wireless connections of base station;
Described field unit further is configured to have indication from described field unit to the transmission of described base station by described reverse link, and sends request with request base station reservation reverse link traffic channel from described field unit in the time slot of appointment by described reverse link.
2. field unit according to claim 1, wherein said code division multiple access transceiver are configured to send described indication and the described request of existing with different power levels.
3. field unit according to claim 1, the wherein frequency band of each channel occupancy 1.25 megahertz.
4. field unit according to claim 1 wherein asks the power level of signal of at least one second type of at least one reverse link traffic channel to be compared with predetermined power threshold.
5. field unit according to claim 4, wherein each reverse link traffic channel is supported the variable-data-rate from 2.4 kbps to 160 kbps.
6. field unit according to claim 1, wherein said code division multiple access transceiver is configured to work in a plurality of assignable radio frequency channel.
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29792501P | 2001-06-13 | 2001-06-13 | |
| US60/297,925 | 2001-06-13 | ||
| US09/997,621 US6678260B2 (en) | 1997-12-17 | 2001-11-29 | System and method for maintaining wireless channels over a reverse link of a CDMA wireless communication system |
| US09/997,621 | 2001-11-29 | ||
| US37869702P | 2002-05-07 | 2002-05-07 | |
| US60/378,697 | 2002-05-07 | ||
| US10/171,080 | 2002-06-12 | ||
| US10/171,080 US7221664B2 (en) | 1998-06-01 | 2002-06-12 | Transmittal of heartbeat signal at a lower level than heartbeat request |
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| CNB028140524A Division CN100534236C (en) | 2001-06-13 | 2002-06-13 | Transmission of heart beat signal at a lower level than heart beat request |
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| CN200910152013.XA Expired - Lifetime CN101626616B (en) | 2001-06-13 | 2002-06-13 | Transmittal of heartbeat signal at a lower level than heartbeat request |
| CN200610091261A Expired - Fee Related CN100581289C (en) | 2001-06-13 | 2002-06-13 | Transmittal of heartbeat signal to reduce error probability |
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| CN1126929A (en) * | 1994-05-12 | 1996-07-17 | Ntt移动通信网株式会社 | A transmission power control method and a transmission power control apparatus |
| CN1165460A (en) * | 1996-03-15 | 1997-11-19 | 松下电器产业株式会社 | CDMA cellular radio transmission system |
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| US5276911A (en) * | 1990-11-02 | 1994-01-04 | Motorola, Inc. | Contention reducing technique for a radio frequency communication system |
| JPH0677963A (en) * | 1992-07-07 | 1994-03-18 | Hitachi Ltd | Communication system and terminal equipment |
| KR100330245B1 (en) * | 1998-06-13 | 2002-08-17 | 삼성전자 주식회사 | Forward link power control device and method in mobile communication system with transmit diversity |
| US7272361B2 (en) * | 1999-12-24 | 2007-09-18 | Ntt Docomo, Inc. | Method and device for transmitting burst signal in mobile communication system, information distribution method, and information distribution controller |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1126929A (en) * | 1994-05-12 | 1996-07-17 | Ntt移动通信网株式会社 | A transmission power control method and a transmission power control apparatus |
| CN1165460A (en) * | 1996-03-15 | 1997-11-19 | 松下电器产业株式会社 | CDMA cellular radio transmission system |
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| CN100581289C (en) | 2010-01-13 |
| CN1897751A (en) | 2007-01-17 |
| CN101626616A (en) | 2010-01-13 |
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| CN101478823A (en) | 2009-07-08 |
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