CN100444684C - Method of dynamic pilot detection threshold for random access of CDMA system - Google Patents

Method of dynamic pilot detection threshold for random access of CDMA system Download PDF

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CN100444684C
CN100444684C CNB2004100701667A CN200410070166A CN100444684C CN 100444684 C CN100444684 C CN 100444684C CN B2004100701667 A CNB2004100701667 A CN B2004100701667A CN 200410070166 A CN200410070166 A CN 200410070166A CN 100444684 C CN100444684 C CN 100444684C
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signature
multipath
demodulation
message
error rate
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CN1731888A (en
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万里龙
任震
丁杰伟
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ZTE Corp
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ZTE Corp
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Abstract

The present invention discloses a method of preamble detection dynamic thresholds for random access of a CDMA system, which belongs to the field of mobile communication. The method comprises the steps that 1. input signals are processed to obtain preamble power time delay distribution with different signatures; 2. all useful multiple paths are recorded; 3. whether the current signature is an effective signature is judged; if the current signature is an ineffective signature, the signature is given up; if the current signature is an effective signature, multi-path management is further carried out for all the useful paths; 4. a message part for random access is demodulated by a demodulating unit; 5. the number of demodulation errors of messages is counted, namely the demodulation error rate of the messages is counted; 6. the preamble detection threshold is dynamically adjusted according to the error rate of the message demodulation. The present invention overcomes the defects of difficulties for selecting thresholds, poor anti-interference performance and high general error rate of a threshold fixing method existing in the prior art; the present invention has the advantages of convenience for selecting the thresholds, improved anti-interference performance, reduction of the error rate, etc.

Description

Method of dynamic pilot detection threshold for random access of CDMA system
Technical field
The present invention relates to mobile communication system, relate in particular to code division multiple access system and insert (RandomAccess) lead detecting method at random.
Background technology
Along with the fast development of mobile communication, people require also more and more higher to the quality of mobile communication and the type of service that provides thereof, and the proposition of 3G (Third Generation) Moblie and development have met people's this demand just, therefore get most of the attention.Wideband Code Division Multiple Access (WCDMA) (WCDMA, Wide CDMA) is a 3-G (Generation Three mobile communication system) standardization body (3 RdGeneration Partnership Project, 3GPP) the Radio Transmission Technology of Ti Chuing (Radio Transmission Technology, RTT) scheme, it not only can provide high-quality voice service, and can provide and the similar multimedia service of fixed network.
In Wideband Code Division Multiple Access (WCDMA) (WCDMA) system, inserting at random is a very important part in the system, be subscriber equipment (User Equipment, UE, set up the prerequisite and the basis of dedicated channel when the terminal equipment in the WCDMA system) calling out after sub-district registration and registration, the performance that therefore inserts part at random seems extremely important.Random access guiding detection method comparatively commonly used at present mainly is to detect leading (as shown in Figure 1) by setting a changeless thresholding, every energy all will be noted greater than the multipath of thresholding T, if certain signature has the energy of a multipath at least greater than thresholding T, then this is signed and is effective signature, otherwise be invalid signature, this method implements comparatively simple, but this method has its weak point.In actual environment; the noise of varying environment is different; and noise often is not the Gaussian noise of standard; the pulsed noise that occurs the short time through regular meeting; for these noises; AGC can not adjust gain immediately and guarantee output steadily, and the noise in the system is stronger than non-pulse formula noise at this moment, and received Signal-to-Noise is littler relatively.In random access procedure, causing reporting message to separate mistake has two kinds of possible reasons, a kind of be detected leading be that noise produces, it is wrong causing the resulting corresponding message of demodulation; Put forward though another kind is the detected leading UE of being, message demodulation is incorrect.The former is after thresholding improves, and along with the attenuating of false alarm probability can reduce, the latter is because pilot power is soaring, and the multipath that surpasses thresholding all is stronger multipath, message is separated wrong quantity and also can to a certain degree be reduced, and promptly overall mistake reduces, on the contrary and thresholding overall wrong can increase when reducing.When wrong number is higher, be necessary to improve thresholding, what guarantee that UE puts forward leadingly has a message demodulation resource, be unlikely to leadingly to be taken all message demodulation resources by what a large amount of noise produced, leadingly be rejected because of temporary transient no demodulation resource on the contrary and UE puts forward, cause turn-on time long, even access fall flat; When wrong number is fewer, illustrate that noise energy is lower, UE puts forward leadingly should all have the message demodulation resource to use, should reduce thresholding, make the preamble retransmission number of times of UE reduce, shorten turn-on time, the power that consumes also reduces, and also reduces the interference to other UE.The dynamic threshold that therefore a self adaptation adjustment preferably can be arranged.Certainly the thresholding adjustment should have a high-low limit, prevents that this feedback control loop from dispersing, and all is disadvantageous because thresholding is too high and cross low to systematic function.
Summary of the invention
The objective of the invention is to select difficulty, poor, the overall higher shortcoming of error rate of interference free performance, in the hope of proposing a kind of method of dynamic pilot detection threshold for random access of CDMA system that can conveniently select thresholding, improve antijamming capability and reduction error rate for thresholding in the fixed threshold method that overcomes the prior art existence.
For achieving the above object, the present invention proposes a kind of method of dynamic pilot detection threshold for random access of CDMA system, it is characterized in that, may further comprise the steps:
The first step: to input signal carry out descrambling, separate frequency deviation, separate signature, correlation product is graded processing, the power time delay that obtains leading difference signature distribute (Power Delay Profile, PDP);
Second step: the energy of each multipath of each signature and detection of preamble thresholding T relatively think useful multipath greater than the multipath of T, write down all useful multipaths;
Whether the 3rd step: differentiating current signature according to second result who goes on foot is effective signature; If have a multipath energy at least greater than T, think that then this signature is effective, entered for the 5th step, promptly give the multipath management all useful multipaths that obtain in second step, the multipath that the multipath management obtains is used for message (message part of Jie Ruing at random) demodulation; If greater than T, think that then this signature is invalid without any the energy of multipath, not demodulation of message (message part of Jie Ruing at random) that this signature is corresponding;
The 4th step: according to the differentiation result in the 3rd step, if invalid signature then enters this step, promptly give up this signature, this signature is not sent AI (Access Indication inserts indication), promptly not corresponding to this signature message (message part of Jie Ruing at random) demodulation;
The 5th step, all useful multipaths of the 3rd step input are done further multipath management, mainly handle as follows: when the phasetophase of two adjacent multipaths apart from less than 1chip (chip, the multipath phase unit of code division multiple access system), reject the less footpath of energy; Multipath phasetophase distance after the multipath management all will be not less than 1chip (chip, the multipath phase unit of code division multiple access system), and the distribution of the multipath after the multipath management processing is flowed to message (message part of Jie Ruing at random) demodulating unit;
In the 6th step, demodulating unit will be according to the multipath distribution demodulation message (message part of Jie Ruing at random) of the 5th step generation;
The 7th step is according to the 6th step demodulation result, statistical message demodulation number of errors within a certain period of time, statistical message demodulation error rate;
In the 8th step, dynamically adjust the detection of preamble thresholding according to the message demodulation error rate; If error rate raises then suitably increases the detection of preamble thresholding; If error rate reduces, then suitably reduce the detection of preamble thresholding.Certainly the thresholding adjustment should have a high-low limit, prevents that this feedback control loop from dispersing, and all is disadvantageous because thresholding is too high and cross low to systematic function.
Method of dynamic pilot detection threshold for random access of the present invention by by loop self adaptation dynamic adjusted threshold, is added up interior message demodulation error rate of a period of time and is dynamically adjusted the detection of preamble thresholding, thereby improve the performance that inserts at random.Compared with prior art, can adjust the detection of preamble thresholding dynamically, the message demodulation error rate is controlled near the desired value, ambient noise and interference are had adaptivity.Big and disturb and be highly resistant to interference in strong at noise, guarantee to insert at random success rate; When noise and interference are little, reduce the transmitting power of UE automatically, energy savings reduces the interference to other UE.The performance of Jie Ruing has improvement preferably than the access performance at random of prior art at random.
Description of drawings
Fig. 1 is an existing method flow diagram in the WCDMA system.
Fig. 2 is a method of dynamic pilot detection threshold for random access of CDMA system flow chart of the present invention.
Embodiment
Be described in further detail below in conjunction with the enforcement of accompanying drawing to technical scheme, according to these accompanying drawings, the technical staff in same field can be easy to realize the present invention.
The present invention has proposed a kind of code division multiple access system that is used for, especially the method for dynamic pilot detection threshold for random access of Wideband Code Division Multiple Access (WCDMA) (WCDMA) system, can adjust the detection of preamble thresholding dynamically, the message demodulation error rate is controlled near the desired value, ambient noise and interference are had adaptivity.Big and disturb and be highly resistant to interference in strong at noise, guarantee to insert at random success rate; When noise and interference are little, reduce the transmitting power of UE automatically, energy savings improves communication system access performance at random.
Fig. 1 is the method flow diagram of the random access guiding detection fixed threshold that prior art adopts in Wideband Code Division Multiple Access (WCDMA) (WCDMA) system.
This logical flow chart starts from step 101, ends at step 106.
Step 101, PDE (Preamble Dection Engine, the detection of preamble engine), to input signal finish descrambling (multiplying each other), separate frequency deviation (multiplying each other) with frequency offseting value with scrambler, separate signature (multiplying each other), coherent integration (by given length coherent integration) with different signatures, obtain power time delay distribution (the Power Delay Profile of 16 signatures like this, PDP), promptly obtain the energy of all multipaths of each signature.
Step 102, for each signature, with the energy and the fixed threshold T comparison of its each multipath, energy is greater than the useful multipath of being recorded as of T, and the multipath that is not more than T is given up.
Step 103, whether the energy in whether at least one multipath footpath that can know this signature from the result of step 102 is greater than T (promptly the energy of strong multipath greater than T), if all multipath energies all are not more than T, illustrate that then this signature is invalid signature, this signature is not sent AI (Access Indication, insert indication), promptly not corresponding to this signature message (message part of Jie Ruing at random) demodulation just enters step 104.If whether at least one multipath energy greater than T (promptly the energy of strong multipath greater than T), illustrate that then this signature is for effectively signing, this signature is sent AI (Access Indication, insert indication), promptly corresponding to this signature message (message part of Jie Ruing at random) demodulation just enters step 105 and step 106.
Step 104 is according to the differentiation result of step 103, if invalid signature, then enter this step, promptly give up this signature, this signature is not sent AI (Access Indication, insert indication), promptly not corresponding message (message part of Jie Ruing at random) demodulation to this signature.
Step 105, differentiation result according to step 103, if effectively sign, enter this step, all useful multipaths of step 102 record are done further multipath management, and main the processing be, when the phasetophase of two adjacent multipaths apart from less than 1chip (chip, the multipath phase unit of code division multiple access system), reject the less footpath of energy.Multipath phasetophase after the multipath management is apart from all being not less than 1chip (chip, the multipath phase unit of code division multiple access system), and the multipath after the multipath management processing distributes and to flow to message (message part of Jie Ruing at random) demodulating unit, and demodulating unit will be according to the multipath distribution demodulation message (message part of Jie Ruing at random) of this step generation.
Step 106, the multipath distribution demodulation message part that management obtains according to step 105 multipath.
Fig. 2 is the method flow diagram that multipath is selected that inserts at random set forth in the present invention.
This logical flow chart starts from step 201, ends at step 206.
Step 201, PDE (Preamble Dection Engine, the detection of preamble engine), to input signal finish descrambling (multiplying each other), separate frequency deviation (multiplying each other), separate signature (multiplying each other) in different signatures with frequency offseting value with scrambler, coherent integration (by given length coherent integration), obtain power time delay distribution (the Power Delay Profile of 16 signatures like this, PDP), promptly obtain the energy of all multipaths of each signature.
Step 202, for each signature, with the energy and the fixed threshold T comparison of its each multipath, energy is greater than the useful multipath of being recorded as of T, and the multipath that is not more than T is given up.
Step 203, whether the energy in whether at least one multipath footpath that can know this signature from the result of step 202 is greater than T (promptly the energy of strong multipath greater than T), if all multipath energies all are not more than T, illustrate that then this signature is invalid signature, this signature is not sent AI (Access Indication, insert indication), promptly not corresponding to this signature message (message part of Jie Ruing at random) demodulation just enters step 204.If whether at least one multipath energy greater than T (promptly the energy of strong multipath greater than T), illustrate that then this signature is for effectively signing, this signature is sent AI (Access Indication, insert indication), promptly corresponding to this signature message (message part of Jie Ruing at random) demodulation just enters step 205 and step 206.
Step 204 is according to the differentiation result of step 203, if invalid signature, then enter this step, promptly give up this signature, this signature is not sent AI (Access Indication, insert indication), promptly not corresponding message (message part of Jie Ruing at random) demodulation to this signature.
Step 205, differentiation result according to step 203, if effectively sign, enter this step, all useful multipaths of step 202 record are done further multipath management, and main the processing be, when the phasetophase of two adjacent multipaths apart from less than 1chip (chip, the multipath phase unit of code division multiple access system), reject the less footpath of energy.Multipath phasetophase after the multipath management is apart from all being not less than 1chip (chip, the multipath phase unit of code division multiple access system), and the multipath after the multipath management processing distributes and to flow to message (message part of Jie Ruing at random) demodulating unit, and demodulating unit will be according to the multipath distribution demodulation message (message part of Jie Ruing at random) of this step generation.
Step 206, the multipath distribution demodulation message part that management obtains according to step 205 multipath.
Step 207, according to step 206 demodulation result, statistical message demodulation error rate (the wrong sum in the certain hour).
Step 208 is dynamically adjusted the detection of preamble thresholding according to the message demodulation error rate.If error rate raises then suitably increases the detection of preamble thresholding; If error rate reduces, then suitably reduce the detection of preamble thresholding.Certainly the thresholding adjustment should have a high-low limit, prevents that this feedback control loop from dispersing, and all is disadvantageous because thresholding is too high and cross low to systematic function.

Claims (4)

1, a kind of method of dynamic pilot detection threshold for random access of CDMA system is characterized in that, may further comprise the steps:
The first step: input signal is handled, and the power time delay that obtains leading difference signature distributes;
Second step: the energy of each multipath of each signature and detection of preamble thresholding T relatively think useful multipath greater than the multipath of T, write down all useful multipaths;
Whether the 3rd step: differentiating current signature according to second result who goes on foot is effective signature; If have a multipath energy at least greater than T, think that then this signature is effective, entered for the 5th step; If greater than T, think that then this signature is invalid without any the energy of multipath, not demodulation of message part that inserts at random that this signature is corresponding;
The 4th step:, if invalid signature is then given up this signature, this signature is not sent and insert indication, the promptly not corresponding message part demodulation that inserts at random to this signature according to the differentiation result in the 3rd step;
In the 5th step, all useful multipaths of second step input are done further multipath management;
The 6th step, the message part that demodulating unit will insert at random according to the multipath distribution demodulation that the 5th step produced;
The 7th step is according to the 6th step demodulation result, statistical message demodulation number of errors within a certain period of time, statistical message demodulation error rate;
In the 8th step, dynamically adjust the detection of preamble thresholding according to the message demodulation error rate.
2, method of dynamic pilot detection threshold for random access of CDMA system as claimed in claim 1 is characterized in that, the described contents processing of the first step comprises descrambling, separates frequency deviation, separates signature, the correlation intergal process.
3, method of dynamic pilot detection threshold for random access of CDMA system as claimed in claim 1 is characterized in that, described the 5th step may further comprise the steps:
When the phasetophase of two adjacent multipaths apart from less than 1 chip the time, reject the less footpath of energy; Multipath phasetophase after the multipath management is apart from all being not less than 1 chip; The distribution of multipath after the multipath management processing is flowed to the message part demodulating unit that inserts at random.
4, method of dynamic pilot detection threshold for random access of CDMA system as claimed in claim 1 is characterized in that, the method for adjusting in the 8th step is: if error rate raises then suitably increases the detection of preamble thresholding; If error rate reduces, then suitably reduce the detection of preamble thresholding.
CNB2004100701667A 2004-08-04 2004-08-04 Method of dynamic pilot detection threshold for random access of CDMA system Expired - Fee Related CN100444684C (en)

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CN101098186B (en) * 2006-06-27 2012-05-09 中兴通讯股份有限公司 Method for determining random access preamble detection dynamic threshold
CN100396143C (en) * 2006-08-09 2008-06-18 华为技术有限公司 Method and device for processing transmission time delay in wide shrouding
CN101442361B (en) * 2007-11-22 2013-12-18 华为技术有限公司 Method for regulating demodulation threshold, terminal and network entity
US8149773B2 (en) * 2008-01-04 2012-04-03 Qualcomm Incorporated Resource allocation for enhanced uplink using an acquisition indicator channel
CN101295999B (en) * 2008-06-27 2014-02-19 中兴通讯股份有限公司 Detection method for accidental precursor access
US8805362B2 (en) 2008-09-11 2014-08-12 Telefonaktiebolaget Lm Ericsson (Publ) Method and arrangement for satisfying performance requirements by tuning parameters for accessing a network with random access channels
CN102256280B (en) * 2011-08-24 2015-04-29 华为技术有限公司 Random access method and equipment thereof

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