GB2430334A - Control of equalizer operation using signal quality thresholds in a receiver - Google Patents

Control of equalizer operation using signal quality thresholds in a receiver Download PDF

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Publication number
GB2430334A
GB2430334A GB0518882A GB0518882A GB2430334A GB 2430334 A GB2430334 A GB 2430334A GB 0518882 A GB0518882 A GB 0518882A GB 0518882 A GB0518882 A GB 0518882A GB 2430334 A GB2430334 A GB 2430334A
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Prior art keywords
receiving
threshold
error correction
quality
decoding
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GB0518882A
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GB0518882D0 (en
Inventor
Go Kaise
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Panasonic Corp
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Panasonic Corp
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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00Baseband systems
    • H04L25/02Details ; Arrangements for supplying electrical power along data transmission lines
    • H04L25/03Shaping networks in transmitter or receiver, e.g. adaptive shaping networks ; Receiver end arrangements for processing baseband signals
    • H04L25/03006Arrangements for removing intersymbol interference
    • H04L25/03012Arrangements for removing intersymbol interference operating in the time domain
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06Receivers
    • H04B1/10Means associated with receiver for limiting or suppressing noise or interference induced by transmission
    • H04B1/1027Means associated with receiver for limiting or suppressing noise or interference induced by transmission assessing signal quality or detecting noise/interference for the received signal
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00Arrangements for detecting or preventing errors in the information received
    • H04L1/004Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0045Arrangements at the receiver end
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00Arrangements for detecting or preventing errors in the information received
    • H04L1/20Arrangements for detecting or preventing errors in the information received using signal quality detector
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00Baseband systems
    • H04L25/02Details ; Arrangements for supplying electrical power along data transmission lines
    • H04L25/03Shaping networks in transmitter or receiver, e.g. adaptive shaping networks ; Receiver end arrangements for processing baseband signals
    • H04L25/03006Arrangements for removing intersymbol interference
    • H04L25/03012Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03019Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00Baseband systems
    • H04L25/02Details ; Arrangements for supplying electrical power along data transmission lines
    • H04L25/06Dc level restoring means; Bias distortion correction decision circuits providing symbol by symbol detection
    • H04L25/061Dc level restoring means; Bias distortion correction decision circuits providing symbol by symbol detection providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset
    • H04L25/062Setting decision thresholds using feedforward techniques only

Abstract

A receiving apparatus, a mobile communication terminal, and a communication system are provided that reduce power consumption and improve receiving performance even when changes occur in the receiving environment. Receiving apparatus 10, incorporated in a mobile communication terminal forming a communication system, has receiving quality threshold setter that receives as input a decoding determining signal outputted from error correction decoder 24 and outputs a threshold for use in determining receiving quality to receiving quality determiner 18. This receiving quality threshold setter 25 is able to adjust (change and correct) the threshold according to the result of error correction decoding outputted from error correction decoder 24. Based on the adjusted threshold, receiving quality determiner 18 determines receiving quality. Based on this determination result, controller 19 controls the operation of equalizer 22 or the operation of equalization and decoding processor 20. Power consumption in the receiver is therefore reduced, when a received signal is of high quality, equalizing is not necessary and is not performed. Also when a received signal is of very low quality, equalizing would not improve the result and equalizing is therefore not performed.

Description

RECEIVING APPARATUS, MOBILE COMMUNICATION TERMINAL, AND

COMMUNICATION SYSTEM

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a receiving apparatus, a mobile communication terminal, and a communication system.

More particularly, the present invention relates to a receiving apparatus that is incorporated inadigitalmobile communication terminal, this digital mobile communication terminal, and a communicationsystemincludingthisdigitalmobilecommunication terminal.

Description of Related Art

Features of mobile communication include that multipaths exist due to the Doppler effect in transmission and reception while in motion, and blocking, reflection and diffraction by buildings. Multipathscauseintersymbolinterferencebetween ) early waves and delayed waves of transmission data. To remove thisintersymbolinterferencefromareceivingsignalandextract original transmission data, the receiving apparatus of amobile communication terminal needs an equalizer.

Recent mobile communication systems demand higher transmission speeds and therefore the use of an equalizer is imperative. However, there is a technical problem that an equali zer consumes substantial power upon reception of a signal, and so the mobile communication terminal using a battery or equivalent power source cannot be used for a long time.

The following patent documents each disclose a method of reducing power consumption in a mobile terminal or in its receiving apparatus.

Japanese Patent PublicationNo. 3257591 discloses amethod which provides a receiving signal level measurer and determiner in a receiving circuit and operating an equalizer only when a decrease is detected in the receiving signal level.

JapanesePatentPublicationNo.26436l4disclosesamethod which stops an equalizer when the receiving signal level is less than a reference value.

Japanese Patent PublicationNo. 3168610 discloses amethod which operates an equalizer only upon receiving a transmission wave.

As shown in FIG.7, the receiving circuit of this type has: antenna 1 that receives transmission data from the transmitting end; high frequency (RF) amplifier 2 that performs amplification and frequency conversion of the receiving signal; 3I A/D converter 3 that performs analogue-to--digital conversion; demodulator 4 that performs demodulation; timing compensation circuit 5 that performs timing compensation of the receiving signal; equalizer 6 that cancels the inter-symbol interference caused by multipath fading; error correcting decoder 7 that performserrorcorrectiondecodingofthereceivingsignalafter equalization processing; and receiving level measurer and determiner 8 that measures quality of the receiving signal and determines the quality.

However, the above-described mobile terminal and its receivingapparatusdonottakeintoconsiderationthefollowing: The abovedescribed mobile terminal and its receiving apparatus cannot change the threshold for receiving quality, which refers to the receiving signal level, even when changes duetotheinfluenceofthepropagationpathoccurinthereceiving environment, including the inter-symbol interference intensity andhigh frequency channel quality (SNR: Signal toNoise Ratio).

As a result, there is a likelihood of causing errors in the data after decoding and causing voice quality deterioration andpacket loss. Furthermore, whenchangesoccurinthereceiving environment, thethresholdforreceivingqualitycannotbechanged in respect to the data that can be subjected to error correction, and, likewise, there is a likelihood of causing voice quality deterioration and packet loss. Consequently, the mobile terminal and its receiving apparatus have a likelihood of causing degradation in receiving performance.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a receiving apparatus, a mobile communication terminal and a communication system that reduce power consumption and that improve receiving performance when changes occur in the receiving environment.

In accordance with one aspect of the present invention, there isprovidedaconfigurationhaving: ameasurerthatmeasures receivingqualityofareceiving signal; anequalizerthat removes inter-symbol interference of the receiving signal; an error correction decoder that detects decoding errors in the receiving signal and performs error correction decoding according to decodingerrordetectionresults; athresholdsetterthatadjusts a threshold for use in determining the receiving quality based ona result of the error correctiondecoding; areceivingquality determinerthatdeterminesthereceivingqualityofthereceiving signal based on the threshold; and a controller that controls anoperationoftheequalizeraccordingtoadeterminationresult of the receiving quality.

Inaccordancewithanotheraspectofthepresentinvention, there is provided a configuration further having: a counter that counts the error correction decoding results; a table that stores a first thresholdanda secondthresholdthat are adjusted according to the receiving quality, and, in this configuration, the threshold setter changes the first threshold and the second thresholdwhen the countermeasures the error correction decoding result to be poor or good over a certain period of time; and 3J the threshold setter changes the first threshold and the second thresholdwhen the countermeasures the error correctiondecoding results to be poor or good over a certain period of time, stops the operation of the equalizer and the error correction decoder when said receiving quality falls below the second threshold, andstartstheoperationoftheequalizerandtheerrorcorrection decoder when the counter measures the error correction decoding results to be good over a certain period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the followingdescriptiontakeninconnectionwiththeaccompanying drawings, in which: FIG.1 is a block diagram showing a receiving apparatus incorporatedinamobilecomrnunicationterminal inacommunication system, according to an embodiment of the present invention; FIG.2(a)-(d) illustrate a method of inter-symbol interference intensity measurement in the receiving apparatus shown in FIG.l; FIG.3 illustrates thresholds for receiving signal level in the receiving apparatus shown in FIG.l; FIG.4 illustrates thresholds for inter-symbol interferenceintensityinthereceivingapparatusshowninFlG. 1; FIG.5 illustrates thresholds for receiving quality in the receiving apparatus shown in FIG.l; FIG.6 illustrates a method of threshold adjustment J according to error correction decoding results in the receiving apparatus shown in FIG.1; and FIG..7 is a block diagram showing a receiving apparatus

of prior art.

DESCRIPTION OF PREFERRED EMBODIMENTS

ma receiving apparatus, amobile communication terminal anda communication system, it is a gist of the present invention toadjust (changeorcompensate) athresholdforuseindetermining receivingqualityaccordingtoerrorcorrectiondecodingresults, measure the receiving quality of a receiving signal based on the adjusted threshold, reflect the measurement result of the receivingqualityuponreceivingprocessingandoperatjon, and control the operation of an equalizer that executes equalization processing.

Now, embodimentsofthepresentinventionwillbedescribed below in detail with reference to the accompanying drawings.

[Configuration of receiving apparatus, mobile communication terminal and communication system) Receiving apparatus 10 of the present embodiment of the present invention shown in FIG.l is incorporated in a mobile communicationterminal, andthis communicationterminal ispart ofacommunicationsystem. ReceivingapparatuslOhas:ameasurer thatmeasures receivingqualityofareceiv ng signal; equalizer 22 that cancels inter-symbol interferenceduetomultipath fading from the receiving signal; error correction decoder 24 that 3 detects decoding errors in the receiving signal and performs error correction decoding according to decoding error detection results; a threshold setter that sets thresholds for use in receiving quality determination according to error correction decodingresults; areceivingqualitydeterminerthatdetermines the receiving quality of the receiving signal measured based on the threshold; and a controller that controls the operation of equalizer 22 according to receiving quality determination results.

In addition, receiving apparatus 10 has: antenna 11 that receives transmission data; a high frequency amplifier 12 that performs amplification an frequency conversion of the receiving signal; A/D converter 13 that performs analogue-to-digital conversion; demodulatorl4thatperformsdemodulationprocessing of the receiving signal; and timing compensation circuit 15 that performs timing compensation of the receiving signal.

In this embodiment, the measurer in receiving apparatus lOhas: receivingleveldetectorl6thatdetects, ma simplified manner, the receiving level of a receiving signal outputted from high frequency amplifier 12 in a simplified manner; and inter-symbol interference intensity measurer 17 that measures, inasimplifiedmanner, the inter-symbol interference intensity of the receiving signal outputted from demodulator 14. The receiving quality determiner has receiving quality determiner 18. This receiving quality determiner 18 receives as input the detection result in receiving level detector 16 and the measurement result in inter- symbol interference intensity measurer 17, receives as input the adjusted threshold from the threshold setter, and determines, based on this threshold, the receiving quality of the receiving signal level and the signal quality of the inter-symbol interference intensity.

In this embodiment, the threshold setter has receiving quality threshold setter 25. This receiving quality threshold setter is connected with error correction decoder 24, and error correction decoder 24 is configured to output a decoding determining signal that represents an error correctiondecoding result, to receiving quality threshold setter 25. In this embodiment, receivingqualitythresholdsetter25 has additional components that are not illustrated: a counter that counts the number of error correction decoding results (i.e. the number ofdecodingdeterminingsignals) andatablethatstoresaplurality of thresholds that are adjusted in accordance with receiving quality.

Now, the multiple thresholds stored in the table include first threshold al and second threshold a2 for determining the receiving qualitylevel, ; firstthresholdt3landsecondthreshold 2 for determining inter-symbol interference intensity (these thresholdswillbedescribedlater) ; and, inaddition, thresholds that adjust (change or correct) determination levels according to changes in the receiving environment. Basically, receiving qualitythresholdmeasurer25adjuststhethresholdinaccordance with the decoding determining signal and outputs the adjusted threshold to receiving quality determiner 18.

The above-described counter incorporated in receiving J qualitythresholdsetter25isdesignedtocounterrorcorrection decoding results and change the threshold, when the error correction decoding results are measured to be poor or good over a certain period of time. The counter has by no means to be provided in receiving quality threshold setter 25. For example, the counter may be incorporated in error correction decoder 24 or may be externally attached to error correction decoder24 (incorporatedinequalizationanddecodingprocessor 20), and output count results to receiving quality threshold setter 25. The operation of receiving quality threshold setter and the threshold will be later described in detail.

Equalizer 22 and error correction decoder 24 form equalizationanddecodingprocessor2o. Thisequalizationand decodingprocessor20hasselector2landcomparator23. Selector 21 selects between outputting the receiving signal outputted from timing compensation circuit 15 to equalize 22 and directly outputting it to comparator 23. Comparator 23 compares the receiving signal which is outputted from equalizer 22 and from which inter-symbol interference is removed, and the receiving signaloutputtedfromtimingcompensationcircuitl5, andoutputs the comparison result to error correction decoder 24.

In this embodiment, controller 19 forms the controller.

Controller 19 outputs an equalization and decoding processing control signal that controls the operation of equalization and decoding processor 20 based on the determination result of the receivingqualityofthereceivingsignaloutputtedfromreceiving quality determiner 18 and outputs an equalizer control signal 33 thatcontrolstheoperationofequalizer22thatformsequalization and decoding processor 20.

[Operation of receiving apparatus] Receiving apparatus 10 first distributes the receiving signal that is subjected to amplification and then frequency conversion in high frequency amplifier 12 to A/D converter 13 and receiving level detector 16 of the measurement means.

Receiving level detector 16 performs receiving signal level measurement.

Meanwhile, A/D converter 13 performs analogue-to-digital conversion, and the receiving signal subjected to demodulation processing in demodulator 14 is inputted in inter-symbol interference intensity measurer 17, and, in this inter-symbol interference intensity measurer 17, the inter-symbol interference intensity is calculated by the following method.

(1) A receiving signal (burst) that is received at receiving apparatus 10 includes a known sequence (i.e. training portion) for estimating the propagation path and channel upon reception, as shown in FIG.2(a) . The known sequence can be extracted from thereceivingsignalafterdemodulationprocessingindemodulator 14 (or after timing compensation in timing compensation circuit 15) (hereinafterthisextractedknownsequencewillbereferred to simply as "extracted known sequence") . Inter-symbol interference intensity measurer 17 has a table (e.g. a memory such as a RAM) that is not illustrated and that stores a preset known sequence for receiving apparatus 10 (hereinafter this 3J stored known signal will be referred to simply as "stored known sequence") . The values are converted so as to establish correlation between the extracted known sequence and the stored known sequence. Here the extracted known sequence "1" is converted to "+1" and "0" is converted to "-1" (hereinafter thisconvertedknownsignalwillbereferredtosimplyas"converted known sequence") (2) As shown in FIG.2(b), the converted known sequence establishes correlation with the stored known sequence on a per symbol basis (hereinafter this correlated known sequence will be referred to simply as "correlated known sequence") The correlation method employed herein is one that determines the product for every symbol.

(3) As shown in FIG.2(c), in this correlated known signal sequence, a sum of the correlation values is calculated on a per symbol basis.

(4) AsshowninFlG.2(d),theinverseofthesumofthecorrelation valuesisdeterminedandthisinverserepresentstheinter-syrnbol interference intensity. For example, when the difference betweenthe extracted known sequence andthe stored known sequence is great, the inter-symbol interference intensity nears "1" (that is, the inter-symbol interference intensity increases) On the other hand, when the difference between the extracted known sequence and the stored known sequence is small, the inter-symbol interference intensity nears "0" (that is, the inter-symbol interference intensity decreases) Next, the receiving signal level detected in receiving 31 level detector 16 is outputted to receiving signal level or receiving quality determiner 18, and the inter-symbol interference intensity measured in inter-symbol interference intensitymeasurerl7 isoutputtedtoreceivingqualitydeterminer 18. Receiving quality determiner 18 determines the receiving signal level and the inter-symbol interference intensity. The thresholds used to determine the receiving signal level and the inter-symbol interference intensity correspond to the equalization processing limit in equalizer 22 and are kept in receiving quality threshold setter 25.

The thresholds set in receiving quality threshold setter include two types, namely the first threshold for determining whether the receiving signal has high enough receiving quality and does not require equalization processing, and the second threshold for determining whether the receiving signal has poor receiving quality and is unlikely to be successfully decoded even if equalization processing is applied.

To be more specific, as shown in FIG.3, the receiving signal level determination involves first threshold al for determining whether the receiving signal level has good enough receiving quality and does not require equalization processing and the second thresholda2 for determining whether the receiving signalhaspoorreceivingqualityandisunlikelytobesuccessfully decoded even if equalization processing is applied. Let us now assume that the receiving signal level is x, and if this receiving signal level x is greater than first threshold al not taking into account the impact of inter-symbol interference J intensity, equalizationprocessingneedsnotbeperformed. On the other hand, when the receiving signal level x is less than threshold a2, there is a likelihood that correct decoding is still not possible even if equalization is performed.

In addition, referring to FIG.4, in determining inter-symbol interference intensity, there are provided first threshold l for determining whether the receiving signal has low enough symbol interference intensity (i.e. good receiving quality) anddoesnot requireequalizationprocessing, andsecond threshold 132 for determining whether the receiving signal has high inter-symbol interference intensity (i.e. poor receiving quality) and is unlikely to be successfully decoded even if equalization processing is applied. Let us now assume that the inter-symbol interference intensity is y, and if this inter-symbol interference intensity y is greater than first threshold 131 not taking into account the impact of the receiving signal level, equalization processing needs not be performed.

On the other hand, when the inter-symbol interference intensity is less than second threshold 132, there is a likelihood that correct decoding is still not possible even if equalization processing is performed.

These fist thresholds al and 131 and second thresholds a2and132canbeadjusted (i.e. changedorcorrected) inreceiving signal threshold setter 25 based on the decoding determining signal outputted from error correction decoder 24.

There is no correlation between the receiving signal level and the intersymbol interference intensity, and receiving J qualitydeterminer l8determinesreceivingqualityofareceiving signal in accordance with the mode configurations in FIG. 5 shown below as (a) - (c) (a) Case where: receiving signal level x > first threshold al and inter- symbol interference intensity > first threshold 131 (b) Case where: receiving signal level x < first threshold al and inter- symbol interference intensity < first threshold 131 (c) Other cases where: above (a) and (b) do not apply.

Incidentally, inFIG.5, regionzlrepresentsthethreshold bandwidth of the difference between first thresholds al and 31. Likewise, region z2 represents the threshold bandwidth of the difference between second thresholds a2 and 2.

Mode (a) refers to case where receiving qualitydeterminer 18 determines that the receiving signal level is high and the inter- symbol interference intensity is low, that is, casewhere receiving quality determiner 18 determines that the receiving quality is high. In this case, equalization processing needs not be performed, and controller 19, shown in FIG.l, outputs an equalizer control signal to selector 21. Selector 21 stops equalization processing by equalizer 22 in accordance with the equalizationcontrolsignalanddirectlytransmitsthereceiving signal after timing compensation to comparator 23.

Mode (b) refers tocasewhere receivingqualitydeterminer 18 determines that the receiving signal level is low and the inter-symbol interference intensityis high, that is, casewhere receiving quality determiner 18 determines that the receiving qualityis low. Inthis case, likelihoodishighthat the correct 3J decodingresultcannotbeobtainedevenifequali zationprocessing is performed, and controller 19 outputs an equalization and decodingprocessingsignaltoequalizationanddecodingprocessor 20. Equalizationanddecodingprocessor2O stops the operation of equalization and decoding processor 20 in response to the equalization and decoding control signal.

That is, equalization and decoding processor 20 stops allequalizationanddecodingprocessing. Whenallequalization and decoding processing stops, receiving apparatus 10 performs processing up to timing compensation circuit 15 and starts (or resumes) the equalization and decoding processing when the receiving signal level and the inter-symbol interference intensity exceed second threshold a2 and second threshold I2.

The equalization and decoding processing are started by the equalization and decoding control signal outputted from controllerl9basedonthereceivingqualitydeterminationresult outputted from receiving quality determiner 18.

Mode (C) refers to case where the receiving signal level and the intersymbol interference intensity are at their normal level, that is, case where the receiving quality id determined to be at normal level. In this case, controller 19 outputs an equalizer control signal to selector 21 and outputs an equalization and decoding signal to equalization and decoding processor2o. Equalizationanddecodingprocessor20performs equalization and decoding processing in response to the equalizationanddecodingcontrolsignal. Selector2ltransmits the receiving signal after timing compensation to equalizer J 22 in response to the equalizer control signal and equalizer 22 performs equalization processing.

In the above-described equalization and decoding processing in receiving apparatus 10, error correction decoder 24 shown in FIG.1 constantly monitors the decoding result of certainsymbolsorthedecodingresultoftheburst. Thedecoding result isoutputtedfromerrorcorrectiondecoder24 andreceiving quality threshold setter 25 as the decoding determining signal.

Here the error correction decoding result can in practice use the result of Viterbi decoding or the result of cyclic redundancy check.

The counter provided in receiving quality threshold setter 25 counts the number of times a decoding determining signal is received and, when correct decoding is not possible and this condition continues over certain symbols and burst, outputs a signal representing the count. In response to the output of the counter, receiving quality threshold setter 25 outputs thresholds that are storedseparatelyinthetableandareadequate for use in receiving quality determination, instead of first thresholds al and 131 and second thresholds a2 and 132 that are then in use in receiving quality determiner 18, to receiving quality determiner 18. That is, the thresholds can be adjusted in receiving quality determiner 18.

Tobemore specific, intheoperationof receivingapparatus 10, cases occurwhere the receivingsignalfulfills the reference value of receiving quality and yet cannot be decoded correctly due to changes in high frequency characteristics and changes 2J in signal power to interference power ratio (i.e. CIR) . For example, as shown in FIG.6, when the receiving quality is in region (thresholdbandwidth) zlandcannotbecorrectlydecoded, errorcorrectiondecoder24outputsadecodingdeterminingsignal, and, in response to this decoding determining signal, receiving qualitythresholdsetter25 outputsathresholdthat is adjusted toliftpartzl, asshownbyarrowA, toreceivingqualitydeterminer 18. As a result, equalizer 22 is able to execute equalization processing.

Also, when the receiving quality is in region z2 and the likelihood is high that correct decoding is still not possible evenifequalizationprocessingisperformed, receivingquality threshold setter 25 outputs a threshold that is adjusted to liftpart z2, as shownbyarrowB, to receiving qualitydeterminer 18. As a result, it is possible not to execute equalization and decoding processing.

On the other hand, there are times when the signal power to interference power ratio improves and a receiving signal doesnotrequireequalizationprocessing. Inthiscase, selector 2 sortsreceivingsignalsaftertimingcompensationandcomparatOr 23 compares a receiving signal that is subjected to equalization processing in equalizer 22 and a receiving signal that skips equalizer 22. As a result, if correct decoding is determined tobe possible without equalizationprocessing, error correction decoder 24 outputs a decoding determining signal to receiving quality threshold setter 25, and, in response to this decoding determiningsignal, receivingqualitythresholdsetter25outputs a threshold shown by arrow C that is adjusted to lower region zi, to receiving quality determiner 18. As a result, it is possible not to perform equalization processing by equalizer 22.

Likewise, when the receiving quality is low and the equalizationanddecodingprocessor2Ohasstoppeditsoperation, the equalization and decoding processing resumes, temporarily, on a regular basis. If, during this regular equalization and decoding processing, a result is obtained over a certain number of times thatareceivingsignal is correctlydecoded, athreshold shownbyarrowDthat is adjustedto lower region z2, is outputted toreceivingqualitydeterminerl8. Asaresult, theequalization anddecodingprocessingbyequalizationanddecodingprocessor is made possible.

Thus, accordingtothepresent embodiment, errorcorrection decoder 24 performs decoding processing of a receiving signal after equalization processing in equalizer 22 and outputs the errorcorrectiondecodingresulttoreceivingqualitythreshold setter 25, and this receiving quality threshold setter 25 is able to adjust (change or compensate) the threshold for use in determining the receiving quality according to the error correctiondecodingresult. Whenareceivingsignalfulfilling certain standard produces error after decoding due to change in the receiving environment, it is still possible to determine thereceivingqualitybasedonthethresholdadjustedinreceiving quality determiner 18, so that the receiving performance of receiving apparatus lOcanbe improved. Improvingthe receiving 3 performanceofreceivingapparatusl0leadstoimprovedreceiving performance of the mobile communication terminal incorporating receiving apparatus 10, consequently improving the overall receiving performance of the communication system.

In addition, the operation of equalizer 22 is controlled according to the adjusted threshold. Tobemore specific, when a receiving signal has high receiving quality and does not require equalization processing or when a receiving signal cannot be correctlydecodedevenwhenequalizationprocessingisperformed, control is executed to stop equalizer 22, and, when a receiving signal has low receiving quality and requires equalization processing, control is executed to start equalizer 22. Power consumption can be reduced thus. In addition, the thresholds foruse indeterminingreceivingqualitycanbeadjusted, making it possible to further improve receiving performance and further decrease power consumption.

As described above, the present invention provides a receiving apparatus, a mobile communication terminal, and a communication system that can reduce power consumption and that can improve receiving performance when there are changes in the receiving environment.

In accordance with one aspect of the present invention, the receiving apparatus of the present invention employs a configurationhaving: ameasurerthatmeasuresreceivingquality of a receiving signal; an equalizer that removes inter-symbol interferenceofthereceivingsignal; anerrorcorrectiondecoder that detects decoding errors in the receiving signal and performs 3J errorcorrectiondecodingaccordingtodecodingerrordetection results; athreshold setter that adjusts a threshold for use in determining the receiving quality based on a result of the error correction decoding; a receiving quality determiner that determines the receiving quality of the receiving signal based on the threshold; and a controller that controls an operation of the equalizer according to a determination result of the receiving quality.

According to this configuration, the error correcting decoder, whichperformsdecodingprocessingofareceivingsignal after equalization processing in the equalizer, outputs the error correction decoding result to the threshold setter, and this threshold setter adjusts (changes or compensates) the threshold for use in determining receiving quality based on the error correction decoding result. Even when the receiving signal fulfilling certain standard produces an error after decodingduetochangesinthereceivingenvironment, thereceiving quality determiner is able to determine the receiving quality of the receiving signal based on the adj usted threshold, thereby improving receiving performance. In addition, the operation oftheequalizeriscontrolledaccordingtotheadjustedthreshold.

To be more specific, when a receiving signal has high receiving quality and does not require equalization processing or when a receiving signal cannot be correctly decoded even when equalization processing is performed, control is executed to stoptheequalizer, and, whenareceivingsignalhaslowreceiving qualityandrequiresequalizationprocessing, controlisexecuted 31 to start the equalizer. Power consumption can be reduced thus.

In accordance with one aspect of the present invention, the receiving apparatus of the present invention employs a configuration further having: a counter that counts error correction decoding results; anda table that stores aplurality of thresholds that are subject to adjustment according to the receiving quality, and, in this configuration, the threshold setter changes the threshold when the error correction decoding results are measured by the counter to be poor or good over a certain time.

In accordance with one aspect of the present invention, the receiving apparatus of the present invention employs a configuration in which a result of error correction decoding in the error correction decoder comprises a Viterbi decoding result and a cyclical redundancy check (CRC) result.

In accordance with one aspect of the present invention, the receiving apparatus of the present invention employs a configuration further having: a comparator that compares the receiving signal after the equalization processing in the equalizer and the receiving signal prior to the equalization processing, and, in this configuration, the threshold setter adj usts the threshold for use in determining the receiving signal based on a result of comparison in the comparator.

In accordance with one aspect of the present invention, the receiving apparatus of the present invention employs a configuration in which the threshold setter adjusts a first threshold and a second threshold; and the controller executes J controlthatstopsanoperationoftheequalizerWhenthereceiving quality in the receiving quality determiner is greater than the first threshold value and stops the operation of the operation oftheequali zerandtheerrorcorrectiondecoderwhenthereceiving quality falls below the second threshold.

In accordance with one aspect of the present invention, the receiving apparatus of the present invention employs a configuration further having: a counter that counts the error correction decoding results; and a table that stores a first threshold and a second threshold that are adjusted according tothereceivingquality, and, inthisconfiguration, thethreshold setter changes the first threshold and the second threshold when the counter measures the error correction decoding result tobepoororgoodoveracertainperiodof time; andthethreshold setter changes the first threshold and the second threshold when the counter measures the error correction decoding results to be poor or good over a certain period of time, stops the operation of the equalizer and the error correction decoder when the receiving quality falls below the second threshold, and starts the operation of the equalizer and the error correction decoder when the counter measures the error correction decoding results to be good over a certain period of time.

In accordance with an aspect of the present invention, themobilecornmunicationterminalofthepresentinventiOnemplOyS aconfigurationhavingtheabove-describedreceivingapparatuS.

In accordance with an aspect of the present invention, the communication system of the present invention employs a 33 configuration having the above-described receiving apparatus.

Thus, the receiving apparatus, mobile communication terminal, and communication system of the present invention eachhavetheadvantageofreducingpowercOnsUmptiOnandimprOving receiving performance even when changes occur in the receiving environment, and are applicable to apparatus and systems having equivalent processing circuits.

The present invention is by no means limited to the above described embodiments, andvarious variations andmodifications may be possible without departing from the scope of the present invention.

This application is based on Japanese Patent Application No.2004-132990, filed April 28, 2004, entire content of which is expressly incorporated by reference herein.

Claims (11)

  1. What is claimed is: 1. A receiving apparatus comprising: a measurer that
    measures receiving quality of a receiving signal; an equalizer that removes inter-symbol interference of the receiving signal; an error correction decoder that detects decoding errors in the receiving signal and performs error correction decoding according to decoding error detection results; a threshold setter that adjusts a threshold for use in determining the receiving quality based on a result of the error correction decoding; a receiving quality determiner that determines the receiving quality of the receiving signal based on the threshold; and a controller that controls an operation of the equalizer according to a determination result of the receiving quality.
    31
  2. 2. The apparatus of claim 1, further comprising: a counter that counts error correction decoding results; and a table that stores a plurality of thresholds that are subject to adjustment according to the receiving quality, wherein the threshold setter changes the threshold when the error correction decoding results are measuredby the counter to be poor or good over a certain time.
  3. 3. Theapparatusofclaiml,whereiflareSUltOferrOrcOrreCtiOfl decoding in the error correction decoder comprises a Viterbi decoding result and a cyclical redundancy check result.
  4. 4. The apparatus of claim 1, further comprising a comparator that compares the receiving signal after the equalization processing in the equalizer and said receiving signal prior to said equalization processing, wherein the threshold setter adjusts the threshold for use in determining the receiving signal based on a result of comparison in the comparator.
  5. 5. The apparatus of claim 1, wherein: the threshold setter adj usts a first threshold and a second threshold; and the controller executes control that stops an operation of the equalizer when the receiving quality in the receiving quality determiner is greater than the first threshold value 3J and stops the operation of the operation of the equalizer and the error correction decoder when the said receiving quality falls below the second threshold.
  6. 6. The apparatus of claim 1, wherein the threshold setter comprises: acounterthatcountstheerrorcorrectiOndecOdingresUlts.
    a table that stores a first threshold anda second threshold that are adjusted according to the receiving quality, wherein: the threshold setter changes the first threshold and the second threshold when the counter measures the error correction decoding result to be poor or good over a certain period of time; and the threshold setter changes the first threshold and the second threshold when the counter measures the error correction decoding results to be poor or good over a certain period of time, stops theoperationoftheequalizerandtheerrOrcOrrectiOfl decoder when said receiving quality falls below the second threshold, and starts the operation of the equalizer and the error correction decoder when the counter measures the error correction decoding results to be good over a certain period of time.
  7. 7. A mobile communication terminal comprising the receiving apparatus of claim 1.
  8. 8. A communication system of comprising the receiving J apparatus of claim 1.
  9. 9. A receiving apparatus substantially as hereinbefore escribedwithreferencetoandasillustratedifltheaccOmpaflyiflg drawings.
  10. 10. A mobile communication terminal substantially as hereinbeforedescribedwithwithreferencetOafldasillUstrated in the accompanying drawings.
  11. 11. A communication system substantially as hereinbefore drawings.
GB0518882A 2005-09-15 2005-09-15 Control of equalizer operation using signal quality thresholds in a receiver Withdrawn GB2430334A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2478004A (en) * 2010-02-23 2011-08-24 Canon Kk Activation or deactivation of decoding at a relay node in response to signal quality
GB2478760A (en) * 2010-03-17 2011-09-21 Phyworks Ltd Adaptive equalizing repeater with output muting control
CN101729189B (en) 2008-10-13 2012-12-26 九旸电子股份有限公司 Transmitting-receiving device and receiver

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5363411A (en) * 1991-06-27 1994-11-08 Nec Corporation Low power consumption receiver with adaptive equalizer
WO2004109947A1 (en) * 2003-06-02 2004-12-16 Qualcomm Incorporated Receiving apparatus with hybrid equalizer and rake receiver and corresponding method of receiving

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5363411A (en) * 1991-06-27 1994-11-08 Nec Corporation Low power consumption receiver with adaptive equalizer
WO2004109947A1 (en) * 2003-06-02 2004-12-16 Qualcomm Incorporated Receiving apparatus with hybrid equalizer and rake receiver and corresponding method of receiving

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101729189B (en) 2008-10-13 2012-12-26 九旸电子股份有限公司 Transmitting-receiving device and receiver
GB2478004A (en) * 2010-02-23 2011-08-24 Canon Kk Activation or deactivation of decoding at a relay node in response to signal quality
GB2478004B (en) * 2010-02-23 2012-05-30 Canon Kk Transmitting data from a relay device to a destination device
GB2478760A (en) * 2010-03-17 2011-09-21 Phyworks Ltd Adaptive equalizing repeater with output muting control
GB2478760B (en) * 2010-03-17 2016-03-23 Phyworks Ltd Adaptive equalizing repeater with output control

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