CN104717722A - PSS interference elimination-based small cell discovery method in ultra dense wireless network - Google Patents
PSS interference elimination-based small cell discovery method in ultra dense wireless network Download PDFInfo
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- CN104717722A CN104717722A CN201510153400.0A CN201510153400A CN104717722A CN 104717722 A CN104717722 A CN 104717722A CN 201510153400 A CN201510153400 A CN 201510153400A CN 104717722 A CN104717722 A CN 104717722A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/16—Discovering, processing access restriction or access information
Abstract
The invention discloses a PSS interference elimination-based small cell discovery method in an ultra dense wireless network. The method comprises the following steps: pre-preparing self-correlation and cross-correlation results of three kinds of PSS time domain signals as templates; carrying out low pass filtration and downsampling on a received signal, and then carrying out cross-correlation operation on the treated received signal with a local PSS copy to find out a peak value to obtain a coarse timing synchronous position of the strongest cell and a formula (shown in the specification); carrying out the cross-correlation operation on the received signal without downsampling and the local PSS copy; finding the highest correlation peak in the cross-correlation result and determining the position and a corresponding formula (shown in the specification); eliminating the corresponding templates from the cross-correlation results of the three PSS time domain signals; and repeatedly finding the highest correlation peak and eliminating. According to the method disclosed by the invention, an existing LT technical manual does not need to be modified. Evaluation signals and reconstruction signals are not required and the complexity and power consumption of UE are not remarkably increased; interference of the synchronizing signals of relatively strong cells on those of relatively weak cells can be further reduced, so that the probability that the UE discovers the relatively weak cells is increased, and the quantity of the small cells which can be discovered by the UE is increased.
Description
Technical field
The invention belongs to the small station discover method in super-intensive wireless network, particularly relate in super-intensive wireless network based on the small station discover method that PSS interference is eliminated.
Background technology
Along with intelligent terminal is popularized, increasing fast appears in mobile data services.When spectrum efficiency be difficult to further raising, increase bandwidth cost high, increase cell density become reply this trend important method.
LTE-A (Long Term Evolution-Advanced) is by the deploy small-cell, macrocell basis in Cellular Networks topology, as Femto cell (Femtocell), picocell (Picocell) and relaying (Relay) etc., realize the optimization to indoor, hot zones and cell boarder.These small-cells are realized covering by low power nodes (LPN, Low Power Node, also known as small station).Because small station is under the covering of macrocell (Macrocell), on existing cellular topology, form the topology of another layer, constitute the isomerism network (HetNet, Heterogeneous Network) of layering.
Since LTE Release 10, to the support in small station with to strengthen be 3GPP (3 always
rdgenerationPartnership Project) tissue reply data service increase an important evolution tendency.On the basis of HetNet, introduce small station at the LTE Release 12 formulated and strengthen (Small Cell Enhancement, SCE) scene.Compared with HetNet, the small station of SCE is deployed in the hot spot region of macrocell, more crypto set, and cluster distribution.And in the super-intensive wireless network in future, small station is disposed and incited somebody to action more crypto set, hundreds of of each macrocell can be reached.
It is exactly that UE (User Equipment) detects small station and the process measuring its RSRP (ReferenceSignal Received Power)/RSRQ (Reference Signal Received Quality) that small station finds.
In super-intensive wireless network, due to the dense deployment in small station, between small station, the interference of synchronizing signal and reference signal is strong, finds that difficulty is caused in small station to UE.And the characteristics such as small station switch (small cell on/off), load balancing, e-ICIC (enhanced-Inter-Cell Interference Coordination), CoMP (Coordinated Multi-point Transmission) all require efficiently, small station discovery fast, find to propose higher performance requirement to small station.Research shows, existing cell search scheme can not meet the requirement that super-intensive network middle and small stations finds.
For solving foregoing problems, small station is found a research direction as LTE Release 12 small station enhanced scene by 3GPP RAN1.Industry has many companies and mechanism conducts a research at this point, and proposes a large amount of relevant motion to 3GPP.Wherein, the solution of UE (User Equipment) side reduces stronger small station to the interference at more small and weak station by PSS IC (InterferenceCancellation), improves the detection probability at more small and weak station.But existing PSS/SSS IC technology needs to estimate channel and reconstruct interference signal, and complexity is higher, can significantly improve cost and the power consumption of UE.Be necessary small station, the UE side discover method that design complexities is lower.
Summary of the invention
Goal of the invention: the object of this invention is to provide and a kind ofly significantly can reduce the interference of stronger small station to more small and weak station, improve the detection probability at more small and weak station, thus improve the small station discover method that UE finds to disturb based on PSS in the super-intensive wireless network of the number in small station elimination.
Technical scheme: for reaching this object, the present invention by the following technical solutions:
Based on the small station discover method that PSS interference is eliminated in super-intensive wireless network of the present invention, comprise the following steps:
S1: prepare root index in advance and be respectively the auto-correlation of three kinds of PSS time-domain signals of 25,29 and 34 and cross correlation results as template;
S2: to received signal low-pass filtering and down-sampled after with local PSS copy do computing cross-correlation, find peak value, obtain the strongest small station coarse timing synchronization position and
S3: do cross-correlation by without down-sampled Received signal strength and local PSS copy;
S4: find relevant peaks the highest in cross correlation results described in step S3, determines the position of relevant peaks and corresponding
S5: by described in step S4 from cross correlation results described in step S1
corresponding template is eliminated;
S6: repeat step S4 and step S5.
Further, the auto-correlation described in step S1 and cross correlation results be described three kinds of PSS time-domain signals when noiseless, interference and decline obtain.
Further, described step S2 comprises the following steps:
S2.1: carry out low-pass filtering to received signal, takes out the 0.93MHz signal at center;
S2.2: carry out to received signal 16 times down-sampled;
S2.3: do computing cross-correlation by through low-pass filtering and down-sampled Received signal strength and local PSS copy, find the peak value in cross correlation results;
S2.4: according to peak value determine the strongest small station coarse timing synchronization position and
Further, described step S3 comprises the following steps:
S3.1: take out (N near coarse timing synchronization position described in step S2
oFDM-N
cP, N
oFDM+ N
cP) in without down-sampled Received signal strength, wherein N
oFDMbe the length of an OFDM symbol, N
cPfor the length of Cyclic Prefix;
S3.2: do cross-correlation without down-sampled Received signal strength and local PSS copy by what obtain in described step S3.1.
Further, described step S5 comprises the following steps:
S5.1: find described in step S4
corresponding template;
S5.2: the template obtained by step S5.1, at time domain superior displacement, makes the peak value of template overlap with the position of the highest relevant peaks described in step S4;
S5.3: the template obtained by step S5.2 carries out the convergent-divergent of amplitude, makes the amplitude of template identical with the amplitude of the highest relevant peaks;
S5.4: from cross correlation results described in step S1, this template is deducted.
Beneficial effect: the present invention has following beneficial effect:
1, this method is deployed in UE end, compared with the small station discover method of network terminal, need not make amendment to existing LTE technical specification.
2, this method is without the need to estimated signal and reconstruction signal, compared with other PSS/SSS interference elimination methods, significantly can not increase complexity and the power consumption of UE.
3, this method can reduce the synchronizing signal in stronger small station to the interference of more small and weak station synchronizing signal, thus improves the probability that UE finds more small and weak station, increases UE institute detectable small station number.
Embodiment
Below the execution mode of the present invention in LTE super-intensive wireless network is described further:
The present invention includes following step:
S1: prepare root index in advance and be respectively the auto-correlation of three kinds of PSS time-domain signals of 25,29 and 34 and cross correlation results as template; Detailed process is as follows:
The undesirable main cause being more small and weak station and being difficult to be detected of the their cross correlation of PSS sequence.
PSS sequence is the zadoff-chu sequence of length N=63.And two zadoff-chu sequences only the difference of root sequence number and sequence length N relatively prime time just there is desirable their cross correlation, namely the amplitude perseverance of cross correlation results is 1/ √ N.
be the difference of the PSS sequence root sequence number of 0 and 2 correspondences be 9, do not meet the requirement relatively prime with sequence length 63.
So can be prepared in advance, root index is respectively the auto-correlation of three kinds of PSS time-domain signals of 25,29 and 34 and cross correlation results as template, after a PSS stronger small station being detected, the template of correspondence is eliminated from cross correlation results.
The detailed process preparing template is: generate the PSS time domain sequences that root index is respectively 25,29 and 34, the cross-correlation between three kinds of PSS time domain sequences and auto-correlation result are kept in UE.
S2: to received signal low-pass filtering and down-sampled after with local PSS copy do computing cross-correlation, find peak value, obtain the strongest small station coarse timing synchronization position and
detailed process is as follows:
In order to reduce computational complexity, near coarse timing synchronization position, only do the fine timing synchronization of PSS, so need first to determine coarse timing synchronization position; First, low-pass filtering to received signal, takes out the 0.93MHz signal at center; The optimum configurations of filter is: band connection frequency 465kHz, stop-band frequency 540kHz, passband ripple 1dB, stopband attenuation 20dB, sample frequency 30.72MHz; Secondly, then do down-sampled to received signal, down-sampled multiple is 16; Finally, do computing cross-correlation by through low-pass filtering and down-sampled Received signal strength and local PSS copy, find peak value, obtain the strongest small station coarse timing synchronization position and
S3: do cross-correlation by without down-sampled Received signal strength and local PSS copy; Detailed process is as follows:
First, (N near coarse timing synchronization position is taken out
oFDM-N
cP, N
oFDM+ N
cP) in without down-sampled Received signal strength, wherein N
oFDMbe the length of an OFDM symbol, N
cPfor the length of Cyclic Prefix, here N
oFDM=1024, N
cP=144; Then, cross-correlation is done by without down-sampled Received signal strength and local PSS copy;
S4: find relevant peaks the highest in cross correlation results described in step S3, determines the position of relevant peaks and corresponding
S5: by described in step S4 from cross correlation results described in step S1
corresponding template is eliminated; Detailed process is as follows:
Find the highest relevant peaks that corresponds to
template, by this template at time domain superior displacement, its peak value is overlapped with the position of the highest relevant peaks, the amplitude of this template is carried out convergent-divergent, make it identical with the amplitude of the highest relevant peaks, finally from cross correlation results, the template of correspondence is eliminated;
S6: repeat step S4 and step S5, obtain many groups
with corresponding timing synchronization position.
Claims (5)
1. disturb based on PSS the small station discover method eliminated in super-intensive wireless network, it is characterized in that: comprise the following steps:
S1: prepare root index in advance and be respectively the auto-correlation of three kinds of PSS time-domain signals of 25,29 and 34 and cross correlation results as template;
S2: to received signal low-pass filtering and down-sampled after with local PSS copy do computing cross-correlation, find peak value, obtain the strongest small station coarse timing synchronization position and
S3: do cross-correlation by without down-sampled Received signal strength and local PSS copy;
S4: find relevant peaks the highest in cross correlation results described in step S3, determines the position of relevant peaks and corresponding
S5: by described in step S4 from cross correlation results described in step S1
corresponding template is eliminated;
S6: repeat step S4 and step S5.
2. in super-intensive wireless network according to claim 1 based on the small station discover method that PSS interference is eliminated, it is characterized in that: the auto-correlation described in step S1 and cross correlation results be described three kinds of PSS time-domain signals when noiseless, interference and decline obtain.
3. disturb based on PSS the small station discover method eliminated in super-intensive wireless network according to claim 1, it is characterized in that: described step S2 comprises the following steps:
S2.1: carry out low-pass filtering to received signal, takes out the 0.93MHz signal at center;
S2.2: carry out to received signal 16 times down-sampled;
S2.3: do computing cross-correlation by through low-pass filtering and down-sampled Received signal strength and local PSS copy, find the peak value in cross correlation results;
S2.4: according to peak value determine the strongest small station coarse timing synchronization position and
4. disturb based on PSS the small station discover method eliminated in super-intensive wireless network according to claim 1, it is characterized in that: described step S3 comprises the following steps:
S3.1: take out (N near coarse timing synchronization position described in step S2
oFDM-N
cP, N
oFDM+ N
cP) in without down-sampled Received signal strength, wherein N
oFDMbe the length of an OFDM symbol, N
cPfor the length of Cyclic Prefix;
S3.2: do cross-correlation without down-sampled Received signal strength and local PSS copy by what obtain in described step S3.1.
5. disturb based on PSS the small station discover method eliminated in super-intensive wireless network according to claim 1, it is characterized in that: described step S5 comprises the following steps:
S5.1: find described in step S4
corresponding template;
S5.2: the template obtained by step S5.1, at time domain superior displacement, makes the peak value of template overlap with the position of the highest relevant peaks described in step S4;
S5.3: the template obtained by step S5.2 carries out the convergent-divergent of amplitude, makes the amplitude of template identical with the amplitude of the highest relevant peaks;
S5.4: from cross correlation results described in step S1, this template is deducted.
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| CN113162878A (en) * | 2021-04-10 | 2021-07-23 | 天津德力仪器设备有限公司 | PSS symbol synchronization method applied to negative signal-to-noise ratio 5GNR system |
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