CN1319293A - Method and device for estimating transmission quality of digital communication signal - Google Patents
Method and device for estimating transmission quality of digital communication signal Download PDFInfo
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- CN1319293A CN1319293A CN99811221A CN99811221A CN1319293A CN 1319293 A CN1319293 A CN 1319293A CN 99811221 A CN99811221 A CN 99811221A CN 99811221 A CN99811221 A CN 99811221A CN 1319293 A CN1319293 A CN 1319293A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/20—Arrangements for detecting or preventing errors in the information received using signal quality detector
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Abstract
Disclosed is a method for estimating the transmission quality of a digital communication signal. According to the inventive method, a variable is determined for each bit of information that is transmitted by a transmitter to a receiver, whereby said variable acts as a measure for the reliability of correct detection thereof and is subjected to low pass filtering. A device (1) for carrying out said method can be connected to an equalizer (3). Said device comprises a low pass filter (5) that filters the probability value and delivers a representative signal for the estimation of transmission quality.
Description
The present invention relates to a kind of method and apparatus of assessing the transmission quality of digital communication signal, wherein be transferred to bit value of Bit Allocation in Discrete of receiver, and measure the measuring of correct reliability of this distribution for transmitter.
This method or device are used for assessing transmission quality especially in the mobile radio system scope, and make used transmission working method and provide the transmission quality of use to be complementary.
After the standard of GSM enhanced full rate (EFR) voice codecs in 1996, the voice codec of realizing this coupling at present is standardized as the next generation among the ETSI SMG11 with the title of adaptive multi-rate (AMR) voice codec.The main purpose of AMR codec is the fixed network quality that obtains speech under different channel conditions, and guarantees the optimal allocation of channel capacity.Codec is carrying out work with the mode of half rate (HR) channel under the good channel condition and/or in the high load capacity sub-district.It dynamically utilizes GSM internal element handing-over and is transformed into full rate (FR) channel mode or does opposite conversion under the situation of bad channel conditions.In a kind of channelling mode (FR or HR), provide multiple coded system to same speech and channel coding rate by variations (rate adaptation).Like this, can realize all having the transmission of best possibility quality by the channel condition of considering variation.
Therefore enough mode (also be channelling mode FR and HR between and/or the conversion coded system between) decisive role of channel quality to selecting transmission to be adopted of assessing exactly, also are like this to whole AMR scheme.Desirable mode should be speech quality that user experience the is arrived standard as preference pattern.Therefore need to determine a kind of tolerance, it can measure the subjective quality of this priori objectively.The possibility of quoting this tolerance of channel quality has: the RxLev of the burst mode in the gsm system and RxQual, DTX activate, frequency hopping activates, from error concealment in residual error ratio, bad frame indicating device (BFI), channel coding-decoder or the voice codec of the channel condition information CSI of the bit of equalizer or burst mode, channel decoder or the like.
What the present invention is based on is to assess transmission quality on the basis of channel condition information (CSI), and for example the equalizer by conventional mobile radio receiver provides described channel condition information with soft bit form.This soft bit is all corresponding to the bit of the signal of communication by wireless radio transmission, and comprises given bit number, and for example 8 or 16.Soft bit can be regarded as the integer that has symbol, and it is worth-2
I-1With 2
I-1Between-1, i=for example 8 or 16, and are provided for the measuring of reliability of identification communication signal bit in equalizer.The value-2 of soft bit like this, for example
I-1The bit " 1 " of expression reliable recognition signal of communication, value 2
I-1The reliable recognition of-1 expression value "+1 ", its intermediate value-1 assignment logic 1, and+1 assignment logic 0.Therebetween value is all corresponding to different reliable recognition.The symbol of soft bit (MSB) comprises the judgement of equalizer, promptly the bit launched of signal of communication be+1 or-1.How the reliability that soft bit value has illustrated this judgement that is to say that this judgement is the measuring of correct reliability of distributing between MSB and the emission bit.
These soft bits are used for recovering as far as possible realistically the signal of communication launched usually in receiver.The measure of reliability that comprises within it is not suitable for the transmission quality of assessment channel.Reason is that the transmission quality of mobile radio channel is subjected to the restriction that the transmission quality that caused by different reasons changes.Like this, in other constant space environment, generally can cause for example so-called short-term decay, cause in several milliseconds promptly that also received power changes fast by reflection, refraction and interference.Move the slow bridging effect that changes of caused geographical environment by single mobile radio users and will cause long-term decay, wherein mean receiving power changed in several seconds the time interval.The short-term decay reduces by in time data block being interweaved the available a kind of simple method of the influence of transmission quality.The received signal short-term degenerates the identification certainty to equalizer is greatly unfavorable, and, as long as this degenerates and can stop by interweaving, the speech quality that just can cause transmitting descends with avoiding, can not consider it when assessment thus.
According to the present invention, the simple possibility that the purpose of transmission quality is assessed in realization simply, apace is exactly that the reliability value of bit transfer sequence is carried out low-pass filtering.
This reliability value preferably obtains from soft bit as follows, and promptly the soft bit value of Huo Deing is the integer that is provided with symbol.
In addition, preferably the reliability value to the transmitted bit of the given first number n asks average before low-pass filtering, wherein, from the bit of given second number N, select and distribute n minimum bit of reliability, and measure this mean value by the reliability value of this n bit.Take the reason of this measure to be; when transmission quality is relatively poor; equalizer also provides usually or distributes many bits with high reliability, so that ask mean time in the reliability value by whole transmitted bits, the mean value that is obtained only represents that the quite insensitive of transmission quality measures.
The relation of number n, N is preferably 5n＜N＜20n, preferred 10n ≌ N.A pulse train of transmission communication signal comprises N=114 bit according to the AMR routine.From these bits, select n=10 least reliable bit and be used to ask average.
In exceeding the blocked-off region of several Hz, preferably adopt and not exclusively suppress to implement low-pass filtering.For example etc. Systolic FIR Filter is suitable for this.Not exclusively rejection ratio adopts situation about suppressing fully to react to the interrupted and lasting variation of transmission quality quickly when filtering.
Signal through low-pass filtering is preferably compared with at least one threshold value, so that obtain comparative result, this result is used as control signal so that change between the different transmission mode of signal of communication.For preventing back and forth conversion apace between transmission mode, when transmission quality changes, introduce hysteresis in the time of can on purpose between different transmission mode, changing in a threshold range.To this, so distribute 2 threshold values can for 2 kinds of different transmission modes, when be lower than 2 threshold values than low value the time, be transformed into second kind from first kind of 2 kinds of transmission modes, when being higher than the high value of 2 threshold values, be transformed into first kind of transmission mode from second kind.If different transmission modes has different data rates, then also preferably the specified bit number N is so that therefrom select total soft bit of least reliable that is, for every kind of transmission mode, this number and its data rate are proportional.Utilize this mode to guarantee: the speed that the variation of transmission quality is reacted is identical to different transmission modes, and irrelevant with the data rate of these transmission modes.
Other features and advantages of the present invention will draw from the following explanation to embodiment in conjunction with the accompanying drawings.Among the figure:
Fig. 1 is the base station block diagram with telecommunication system of mobile terminal device, and there is a device according to assessment transmission quality of the present invention this base station;
Fig. 2 is the block diagram of mobile terminal device, and this terminal equipment is furnished with a device and communicates with base station among Fig. 1 according to the present invention;
Fig. 3 shows in communication signal procedure the measuring process to long-term decay;
When Fig. 4 shows in a pulse train 10 bits with least reliability value is averaged, to the assessment result of the quality of reception of same communication signal;
Result when Fig. 5 shows whole bits of a pulse train are averaged;
Fig. 6 shows the impulse response and the frequency characteristic of the low pass filter of apparatus of the present invention; And
Fig. 7 has illustrated that the assessed value of signal of communication transmission quality is converted into control signal, for use in changing between different transmission modes.
Fig. 1 shows the part of the base station of telecommunication system with the form of simplified block diagram, the transmission quality of this telecommunication system operative installations 1 assessment digital communication signal.The base station receives digital communication signal by antenna 2.Being connected equalizer 3 on the antenna 2, to provide a width to each bit that receives from antenna be the soft bit of 8 bits for example.
The output end signal of equalizer is fed to treatment circuit so that the signal of communication of reconstruction transmission, and this treatment circuit does not draw in the drawings.In addition, the output of equalizer links to each other with the input of the CSI generator 4 of apparatus for evaluating 1.The short-term decay of CSI generator 4 assessment transmission channels wherein, is measured the transmission quality of each pulse train of signal of communication by it.According to the communication signal transmission pattern, this signal of communication comprises the pulse train of varying number in each Speech frame.In the full rate transmission, a Speech frame comprises 4 pulse trains, and is 2 pulse trains in the half rate transmission.
For the equalizer with 8 bit resolutions, the processing of every individual pulse string is to realize according to following c program code.
The c program code:
Word16 num_to_compute=10 Word16 sort[128]; / * initialization */for (n=0; N＜128; N++) sort[n]=0/* counts */for (n=0 to the bit with certain reliability; N＜114; N++) sort[abs (burst[n])] ++; N=0; Summe=0; While (1) if (sort) [n]==bit that 0/* does not have a reliability is n*/n++; Else{ if (sort) [n]＜num_to_compute) [summe+=sort[n] * n; / * measures the bit number */n++ that also should calculate; Else{ summe+=num_to_compute*n; Break;
The symbol of each soft bit is always consistent with the guess value that receives bit, and numerical value is a count value between 0～127, and this numerical value comprises the measuring of reliability of sign determination.At this, numerical value 0 is used for the very insecure judgement of expression, and 127 are used for the very reliable judgement of expression.
For 2 of reliability information
7=128 kinds of possible different values, setting up size is 128 temporary transient data segment ＂ sort ＂, and uses 0 initialization.In first circulation, being single soft bit ＂ burst[n at first by asking numerical value] ＂ (0＜n＜114) obtains the corresponding to probabilistic quantity of corresponding bits of soft bit symbol and transmission signals, and measure the amount of bits in the pulse train with certain reliability value, and leave among the data segment ＂ sort ＂ corresponding to this value.At this, the exponential representation reliability of data segment, the content representation of data segment have the amount of bits in pulse train of this reliability.Therefore, for example (,) ＂ sort[10]=12 ＂ just mean 12 bits with 10 reliabilities.In second circulation, from index 0 with least reliability, the reliability value of at least 10 reliable bits of accumulative total.Just obtain first mean value by the summation that will obtain divided by the bit number that adds up.
In addition, CSI generator 4 is carried out the calculating of second mean value, wherein, adds the pulse train least reliability value of K pulse train at every turn on the basis of the mean value of above-mentioned 10 bits, and is divided by with K.Number K equals 2 in the half rate transmission, equal 4 in the full rate transmission.Also be the pulse train number that it is equivalent to every frame, the data rate of it and transmission mode is proportional in other words.Because the quantity of the pulse train of considering depends on transmission mode, thus the calculating by second mean value, can with fixing, provide the assessed value of transmission quality with the irrelevant repetition rate of transmission rate.
The short-term decay of the mobile radio channel that passes through this average output signal that obtains and transmit communications signals of CSI generator 4 is proportional approx.The caused thus great changes of the output signal of CSI generator 4 can utilize low pass filter 5 to suppress.The reason of using low pass filter 5 to replace averaging in the bigger time interval is, simply average and to cause unsafty result what a plurality of frames carried out, because the powerful interference of short-term also can cause reducing significantly the transmission quality of assessment, even this reduction is the short time, so that can compensate it by interweaving, but described reduction may think that also the conversion of transmission mode is necessary.So the mean value calculation of no weighting shows that low pass filter is very poor.Therefore, on apparatus for evaluating 1, the low pass filter 5 that will have following specification is connected to the output of CSI generator 4:
-filter type: FIR etc. the low pass filter (constant blocked-off region) of pulsing
-filter order: 28
-sampling rate: 50Hz
-passband: 0.2Hz
-blocked-off region: be 1.8Hz when 20db decays
Fig. 6 partly shows the transfer function h (t) of this filter at A, and it is the frequency characteristic 201og (| H2 (π f) |) of unit that the B part shows with the decibel with the functional form of frequency f (Hz).Also can consider other possibility of low-pass filtering in principle, such as Butterworth filter, Tschebyscheff filter, iir filter or the like, or be weighted and average that wherein the weighting of soft bit increases and reduces along with timeliness.
It is the measurement curve of the long-term decay of practical communication signal on 2000 frames of 40 seconds that Fig. 3 showed corresponding to the time interval (transmission rate is per second 50 frames).Having marked and drawed on abscissa is the signal to noise ratio C/ (I+N) of unit with the decibel.
Fig. 4 shows the assessment situation to the quality of reception of the signal of communication with attenuation characteristic shown in Figure 3, and this assessment situation is provided by low pass filter 5.Marked and drawed the digital value of the output signal of low pass filter 5 on abscissa, this value is (for the soft bit of 8 bit widths) between 0～127.As can be seen, among Fig. 3 the extreme value of signal quality go out now and Fig. 4 be about 700,1070 with 1490 frames on assessment be very consistent.The amplitude of assessment deviation is also just in time consistent with the process shown in Fig. 3 among Fig. 4.
Fig. 5 shows the comparison of assessment result, considered whole 114 soft bits of pulse train in this assessment, rather than situation as shown in Figure 4 like that only has 10 bits of least reliability value.Though the position of extreme value is just in time consistent with the extreme value place among Fig. 3, the amplitude of deviation has reduced makes an appointment with half.When 760 frames, assessment shows minimum value, and the minimum value neither one of measured attenuation curve is consistent with this minimum value among Fig. 3.Therefore, total assessment reliability is littler than situation shown in Figure 4.
As can be seen, by from the pulse train of N=114, selecting n=10 bit, and it is asked on average, can reproduce measurement curve process shown in Figure 3 well with least reliability value.Clearly, according to service condition, quality or the other factors of equalizer 3, other value of the number n of selected bits also can make to assess with tested Quality Process and realize consistency preferably.Suppose the relation that in the important situation of reality, need satisfy 5n＜N＜20n.
The output signal of low pass filter 5 is connected in the input of so-called metric generator 6.This metric generator 6 relates to a kind of improved comparator, and it compares the output signal of filter and a plurality of threshold value, and produces the control signal of 2 bit widths according to comparative result.In Fig. 7, show and the corresponding horizontal line A of threshold value, B, C by the curve that conforms to curve shown in Figure 3.If the output signal L of low pass filter 5
FilteringBigger than threshold value B, then transmission quality is fine, and control signal just has binary value 10.When having B＞L
FilteringDuring the good channel quality of＞A, control signal just has binary value 11, has A＞L
FilteringDuring the poor channel quality of＞C binary value 01 is arranged, and at L
FilteringDuring＞10 very poor channel quality, then value is 00.As can be seen, as filter output signal L
FilteringWhen surpassing value of threshold value, then all have only a control signal bit changing; Also be that control signal is to adopt Gray code.
Threshold value A, B, C can freely select, and the boundary of all given conversion transmission mode.It has following meaning:
-threshold value A: when being lower than this threshold value, the transport mode translations that will have the highest speech speed is to the transmission mode with medium speech speed,
-threshold value B: when surpassing this threshold value, the transport mode translations that will have medium speech speed is to the transmission mode with the highest speech speed, and
-threshold value C: the transport mode translations that will have medium speech speed is to the transmission mode with minimum speech speed and do opposite conversion.
As long as the threshold value B that selects then can cause hysteresis to transfer process than threshold value A height, also promptly when being transformed into flank speed, moderate rate must be better than the channel quality when flank speed is transformed into moderate rate.Therefore, when channel quality changes, can prevent conversion constantly between these two kinds of transmission modes in threshold value A, B scope.
Control signal is connected in the first input end of control unit 7.Analyze described control signal by this control unit 7, and be the transmission realization rate-matched of mobile terminal device to base station (up link).To this, it with desired uplink rate (UL_REQ speed) jointly, also promptly be transferred to mobile terminal device with the speech bit.In contrast, mobile terminal device transmits the uplink rate of launching with " UL speed ", and this control signal is transferred to the base station.
Fig. 2 shows the simplified block diagram of mobile terminal device, and this mobile terminal device can be worked with the base station of Fig. 1.It resembles and comprises equalizer 3 base station, and this equalizer offers apparatus for evaluating 1 by the signal of communication that receives by antenna 2 with soft bit, and apparatus for evaluating 1 resembles fully and includes CSI generator 4, low pass filter 5 and metric generator 6 base station of Fig. 1.The control signal that is produced by metric generator 6 is transferred to the control unit 7 of base station by antenna 8, and these control unit 7 the same control signals that provide according to mobile terminal device as indicated above are mated the transmission mode of down link.
Analyze the control signal that receives by mobile terminal device by antenna 2 by control unit 7, the signal that its mode is provided as the metric generator 6 of analyzing the base station.
With signal L
FilteringThe control signal that converts 2 bit widths to is necessary, because in order to control the coupling of the downlink rate from the base station to the mobile terminal device, control unit 7 need be offered its information about downlink quality all the time by mobile terminal device., only provide several bits seldom to be used to transmit this information.Therefore, the most significant bit of a transmission filter output signal L filtering will cause rough quantification.On the contrary, transmission just must be divided into a plurality of frames through filter output signal fine quantization or complete, and this can cause changing the obvious increase of delaying.On the contrary, the control signal of 2 bit widths of metric generator 6 can be transferred to the base station in each Speech frame, makes this base station to redefine transmission mode according to each Speech frame.
This control signal analysis in the control unit 7 can be achieved as follows for the transmission of uplink and downlink link in a like fashion: will distribute to two control signal value 10,11,01 and 00 respectively with the numerical value 3,2,1 or 0 of transmission quality monotone variation.Current numerical value and last 7 numerical value (also promptly to the assessment result of the transmission quality of last 8 frames) addition, and select to determine the transmission mode of speech transmissions speed according to this summation.This value is used to launch in down link, and is sent to mobile terminal device as the instruction of regulating uplink rate in up link.
Numerical value in succession all can only change a level, and in other words, for example following can only be numerical value 3 or 2 in numerical value 3 back once more.In view of the above, determined thus transmission rate also can only change one-level between 2 frames.This can be used as prior information and uses, so that reduce transmission error and reduce the very big speech modulus error of interference thus.
Described herein in order to replace, by base station control unit the used transmission mode of uplink and downlink link is carried out centralized judgement, also can imagine a kind of modified model, wherein, decide transmission mode up and/or that down link adopted by mobile terminal device self, and corresponding therewith regulating command is sent to the base station.
Claims (24)
1. assess the method for the transmission quality of digital communication signal, wherein be transferred to bit value of Bit Allocation in Discrete of receiver for transmitter, and measure measuring of this distribution reliability, it is characterized in that measuring by the reliability value of bit sequence of transmission is carried out low-pass filtering of transmission quality obtains.
2. method according to claim 1 is characterized in that, measures the value of described reliability by bit and measures, and comprehensively becomes a unified data word (soft bit), and utilizes the Numerical Implementation low-pass filtering of this soft bit.
3. method according to claim 1 and 2 is characterized in that, the probable value to the transmitted bit of the given first number n before low-pass filtering is asked on average, and utilizes the mean value that is obtained to carry out low-pass filtering.
4. method according to claim 3 is characterized in that, selects n the bit that distributes correctness to have minimum probability from the bit of given second number N, and passes through the described mean value of probability calculation of this n bit.
5. method according to claim 4 is characterized in that, for each probable value of described probability is measured the number that is arranged in those bits this N bit, that have this value.
6. according to claim 4 or 5 described methods, it is characterized in that, 5n＜N＜20n, and be preferably 10n ≌ N.
7. according to claim 4,5 or 6 described methods, it is characterized in that a described N bit always is formed in the OU of transmission communication signal between the transmitter and receiver.
8. according to one of aforesaid right requirement described method, it is characterized in that having the low-pass filtering of imperfect inhibition at blocked-off region.
9. according to one of aforesaid right requirement described method, it is characterized in that, compare through measuring of low-pass filtering, so that the comparative result that acquisition is changed the different transmission mode of signal of communication with the control signal form with at least one threshold value (A, B, C).
10. method according to claim 9, it is characterized in that, 2 kinds of different transmission modes are so distributed 2 threshold values (A, B), when being lower than the low threshold value (A) of 2 threshold values with box lunch, first kind from 2 kinds of transmission modes is transformed into second kind, and when the higher thresholds that is higher than 2 threshold values (B), be transformed into first kind from second kind of transmission mode.
11., with regard to relating to claim 4, it is characterized in that described different transmission mode has different data rates according to claim 9 or 10 described methods, and regulation, for every kind of transmission mode, second number N is all proportional with data rate.
12. the device of the transmission quality of assessment digital communication signal, be used to be connected the output of the equalizer (3) of communication signal receiver, wherein, described device (1) receives the bit value of being distributed to these bits by equalizer (3) for the bit that transmitter transmitted from equalizer (3), and receive the measuring of distribution reliability of institute's transmitted bit, it is characterized in that, described device (1) comprises low pass (5), and this low pass (5) smoothly provides the signal of expression transmission quality assessment by the quick variation of measure of reliability to the bit sequence of transmission.
13. device according to claim 12 is characterized in that, it includes counting circuit (4) so that the mean value of the measure of reliability of the transmitted bit of calculating given number n.
14. device according to claim 13 is characterized in that, described counting circuit (4) has a kind of device, and being used for from quantity is that (bit of N＞n) is selected the described n bit that least reliability is measured that has to N.
15. device according to claim 14 is characterized in that, described measure of reliability is the digital value of i bit width, and the described device that is used to select (4) comprises 2
iIndividual memory location is so that the frequency numerical value that probable value occurred that storage presents.
16. device according to claim 15 is characterized in that, a described N bit has constituted the OU of transmission communication signal between transmitter and receiver.
17., it is characterized in that described low pass filter (5) has incomplete inhibition at blocked-off region according to the described device of one of claim 12 to 16.
18., it is characterized in that described low pass filter (5) such as is at the Systolic FIR low pass filter according to the described device of one of claim 12 to 17.
19. according to the described device of one of claim 12 to 18, it is characterized in that metric generator (6), this metric generator (6) receives the output signal of low pass filter (5), this output signal and at least one threshold value (A, B, C) are compared, but also an output signal is provided, this output signal is determined an available transmission mode according to comparative result.
20. device according to claim 19, it is characterized in that, described metric generator (6) compares output signal and 2 threshold values (A, B) of low pass filter (5), and when being lower than the low threshold value (A) of 2 threshold values, control signal is become second kind of state from first kind of state exchange, when the higher thresholds that is higher than 2 threshold values (B), from second kind of state exchange to the first kind of state.
21. the mobile terminal device of mobile radio system is characterized in that, it comprises the described device of claim 12 to 20 (1), and this terminal equipment is provided for and will be transferred to the base station by the control signal that the expression transmission quality that device (1) provides is assessed.
22. terminal equipment according to claim 21 with regard to relating to claim 19 or 20, is characterized in that, the control signal that is transferred to the base station is the output signal of metric generator (6).
23. the base station of mobile radio system, it is characterized in that, it comprises the described device of claim 12 to 20 (1), and contain control unit (7), this control unit is determined the transmission mode that adopted during in transmission between base station and the mobile terminal device that distributed according to the control signal of expression transmission quality assessment.
24. base station according to claim 23 is characterized in that, described control unit (7) is provided for by the transmission mode of being determined by mobile terminal device institute control signals transmitted to be adopted.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19843468.5 | 1998-09-22 | ||
| DE19843468 | 1998-09-22 |
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| Publication Number | Publication Date |
|---|---|
| CN1319293A true CN1319293A (en) | 2001-10-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN99811221A Pending CN1319293A (en) | 1998-09-22 | 1999-09-01 | Method and device for estimating transmission quality of digital communication signal |
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| Country | Link |
|---|---|
| EP (1) | EP1116355A1 (en) |
| JP (1) | JP2002525970A (en) |
| KR (1) | KR20010088811A (en) |
| CN (1) | CN1319293A (en) |
| AU (1) | AU1029900A (en) |
| BR (1) | BR9913984A (en) |
| WO (1) | WO2000018058A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006034654A1 (en) * | 2004-09-30 | 2006-04-06 | Zte Corporation | An adaptive multi rate transmission method in the wireless local area network |
| CN100448206C (en) * | 2003-09-18 | 2008-12-31 | 西安电子科技大学 | Multi-rate transmission method of radio local network |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4145032B2 (en) * | 2001-08-07 | 2008-09-03 | 富士通株式会社 | Wireless LAN system |
| DE10164796B4 (en) * | 2001-09-06 | 2004-12-09 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Device and method for characterizing a transmission channel |
| ES2509292T3 (en) | 2004-02-12 | 2014-10-17 | Core Wireless Licensing S.à.r.l. | Classified media quality of an experience |
| JP2019062289A (en) * | 2017-09-25 | 2019-04-18 | 日本電気株式会社 | Communication control device, terminal, and mobile communication system |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE470372B (en) * | 1992-06-23 | 1994-01-31 | Ericsson Telefon Ab L M | Method and device for estimating the quality of frame error detection in the receiver of a radio communication system |
| FI103850B1 (en) * | 1996-07-12 | 1999-09-30 | Nokia Mobile Phones Ltd | Automatic control of communication mode |
-
1999
- 1999-09-01 EP EP99953652A patent/EP1116355A1/en not_active Withdrawn
- 1999-09-01 JP JP2000571604A patent/JP2002525970A/en not_active Withdrawn
- 1999-09-01 WO PCT/DE1999/002737 patent/WO2000018058A1/en not_active Application Discontinuation
- 1999-09-01 AU AU10299/00A patent/AU1029900A/en not_active Abandoned
- 1999-09-01 CN CN99811221A patent/CN1319293A/en active Pending
- 1999-09-01 BR BR9913984-7A patent/BR9913984A/en not_active IP Right Cessation
- 1999-09-01 KR KR1020017003700A patent/KR20010088811A/en not_active Application Discontinuation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100448206C (en) * | 2003-09-18 | 2008-12-31 | 西安电子科技大学 | Multi-rate transmission method of radio local network |
| WO2006034654A1 (en) * | 2004-09-30 | 2006-04-06 | Zte Corporation | An adaptive multi rate transmission method in the wireless local area network |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20010088811A (en) | 2001-09-28 |
| JP2002525970A (en) | 2002-08-13 |
| BR9913984A (en) | 2001-06-19 |
| WO2000018058A1 (en) | 2000-03-30 |
| AU1029900A (en) | 2000-04-10 |
| EP1116355A1 (en) | 2001-07-18 |
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