Source: http://www.google.com/patents/US20090303960?ie=ISO-8859-1
Timestamp: 2014-10-21 20:03:30
Document Index: 436041817

Matched Legal Cases: ['application No. 200710073057', 'application No. 200710100449', 'application No. 200710103147', 'application No. 200710112774', 'application No. 200710123676', 'application No. 200610173364']

Patent US20090303960 - Method and apparatus for allocating and processing sequences in ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA method and apparatus for allocating and processing sequences in a communication system is disclosed. The method includes: dividing sequences in a sequence group into multiple sub-groups, each sub-group corresponding to its own mode of occupying time frequency resources; selecting sequences from a candidate...http://www.google.com/patents/US20090303960?utm_source=gb-gplus-sharePatent US20090303960 - Method and apparatus for allocating and processing sequences in communication systemAdvanced Patent SearchPublication numberUS20090303960 A1Publication typeApplicationApplication numberUS 12/493,869Publication dateDec 10, 2009Filing dateJun 29, 2009Priority dateMar 7, 2007Also published asDE602008004885D1, EP2101419A1, EP2101419A4, EP2101419B1, US8249006, US8588168, US8644239, US20120087326, US20120281671, US20140056281, WO2008106894A1Publication number12493869, 493869, US 2009/0303960 A1, US 2009/303960 A1, US 20090303960 A1, US 20090303960A1, US 2009303960 A1, US 2009303960A1, US-A1-20090303960, US-A1-2009303960, US2009/0303960A1, US2009/303960A1, US20090303960 A1, US20090303960A1, US2009303960 A1, US2009303960A1InventorsBingyu Qu, Yujuan HE, Xuan FENGOriginal AssigneeBingyu Qu, He Yujuan, Feng XuanExport CitationBiBTeX, EndNote, RefManPatent Citations (6), Non-Patent Citations (1), Referenced by (3), Classifications (23), Legal Events (1) External Links: USPTO, USPTO Assignment, EspacenetMethod and apparatus for allocating and processing sequences in communication systemUS 20090303960 A1Abstract A method and apparatus for allocating and processing sequences in a communication system is disclosed. The method includes: dividing sequences in a sequence group into multiple sub-groups, each sub-group corresponding to its own mode of occupying time frequency resources; selecting sequences from a candidate sequence collection corresponding to each sub-group to form the sequences in the sub-group by: the sequences in a sub-group i in a sequence group k being composed of n sequences in the candidate sequence collection, the n sequences making a |ri/Ni−ck/Np 1 | or |(ri/Ni−ck/Np 1 ) modu mk,i| function value the smallest, second smallest, till the nth smallest respectively; allocating the sequence group to cells, users or channels. It prevents the sequences highly correlated with the sequences of a specific length from appearing in other sequence groups, thus reducing interference, avoiding the trouble of storing the lists of massive sequence groups.
dividing sequences in a sequence group into multiple sub-groups, each sub-group corresponding to a mode of occupying time frequency resources; selecting sequences from a candidate sequence collection corresponding to each sub-group to form the sequences in the sub-group by: the sequences in a sub-group i in a sequence group k being composed of n sequences in the candidate sequence collection, wherein n is a natural number, the n sequences making a |ri/Ni−ck/Np 1 | or |(ri/Ni−ck/Np 1 ) modu mk,i| function value a smallest, a second smallest, until an nth smallest respectively, wherein i is a serial number of the sub-group, k is a serial number of the sequence group, Np 1 is the length of a reference sub-group sequence, ck is a basic sequence index of a sequence with a length of Np 1 determined by the sequence group k; wherein ri is a basic sequence index in the candidate sequence collection, and Ni is the length of a sequence in the candidate sequence collection; wherein mk,i is a variable dependent on the group number k and the sub-group number i; and allocating the sequence group to at least one of: cells, users or channels. 2. The method of claim 1, wherein: the sequences correspond to at least one of: Zadoff-Chu sequences or Gauss sequences.
3. The method of claim 2, wherein n=└Ni/Np 1 ┘, └z┘ represents a maximum integer not greater than z.
making ri an integer value of ck�Ni/Np 1 rounded up or down, which makes the function |ri/Ni−ck/Np 1 | the smallest value. 5. A method for processing sequences in a communication system, comprising:
obtaining a group number k of a sequence group allocated by the system; selecting n sequences from a candidate sequence collection to form sequences in a sub-group i in a sequence group k; the n sequences making a |ri/Ni−ck/Np 1 | or |(ri/Ni−ck/Np 1 ) modu mk,i| function value a smallest, a second smallest, until an nth smallest respectively; wherein n is a natural number, i is a serial number of the sub-group; wherein Np 1 is the length of a reference sub-group sequence, ck is a basic sequence index of a sequence with a length of Np 1 determined by the sequence group k; wherein ri is a basic sequence index in the candidate sequence collection, and Ni is the length of a sequence in the candidate sequence collection; wherein mk,i is a variable dependent on the group number k and the sub-group number i; generating corresponding sequences according to the sequences in the formed sub-group; and communicating the sequences on time frequency resources corresponding to the sub-group i. 6. The method of claim 5, wherein: the sequences correspond to at least one of: Zadoff-Chu sequences or Gauss sequences.
7. The method of claim 6, wherein n=└Ni/Np 1 ┘, └z┘ represents a maximum integer not greater than z.
8. The method of claim 5, wherein mk,i=1/B, and wherein B is a natural number.
pre-storing mk,i (1≦k≦T/2) corresponding to k and i. 10. The method of claim 8, further comprising:
pre-storing mk,i (T/2<k≦T) corresponding to k and i, wherein T is the total quantity of sequence groups. 11. The method of claim 8, wherein: if Ni≧Lr, then mk,i=1 wherein Ni is the length of a sequence in the candidate sequence collection corresponding to the sub-group i, and Lr is determined by a reference sub-group sequence length Np 1 .
12. The method of claim 8, wherein the basic sequence index ri=B−1�round(B�ck�Ni/Np 1 ) makes a function d(a,b) value the smallest, where B−1 is a natural number that meets B�B−1 mod Ni=1 and round(z) represents an integer closest to z.
13. The method of claim 5, wherein the function |ri/Ni−ck/Np 1 | or |(ri/Ni−ck/Np 1 ) modu mk,i| varies between at least one of: different sequence groups, or different sub-groups of one sequence group.
making ri an integer value of k�Ni/N1 rounded up or down, which makes the function |ri/Ni−ck/Np 1 | the smallest value. 15. A sequence processing apparatus, comprising:
a sequence selecting unit configured to: obtain a group number k of a sequence group allocated by a system, and select n sequences from a candidate sequence collection to form sequences in a sub-group i in the sequence group k, wherein the n sequences make a |ri/Ni−ck/Np 1 | or |(ri/Ni−ck/Np 1 ) modu mk,i| function value a smallest, a second smallest, until an nth smallest respectively, wherein i is a serial number of the sub-group, k is a serial number of the sequence group, Np 1 is the length of a reference sub-group sequence, ck is a basic sequence index of a sequence with a length of Np 1 determined by the sequence group k; wherein ri is a basic sequence index in the candidate sequence collection, and Ni is the length of a sequence in the candidate sequence collection; wherein mk,i is a variable dependent on the group number k and the sub-group number i; and a sequence processing unit configured to: generate corresponding sequences according to the sequences in the formed sub-group i, and process the sequences on time frequency resources corresponding to the sub-group i. 16. The sequence processing apparatus of claim 15, wherein:
the sequence processing unit is a sequence communicating unit configured to generate the corresponding sequences according to the formed sequences and communicate the sequences on the corresponding time frequency resources. Description
CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of International Application No. PCT/CN2008/070431, filed on Mar. 6, 2008, titled �sequence distributing, processing method and apparatus in communication system�, which claims the priority of CN application No. 200710073057.4, filed on Mar. 7, 2007, titled �method and apparatus for allocating and processing sequences�, CN application No. 200710100449.5, filed on Apr. 9, 2007, titled �method and apparatus for allocating and processing sequences�, CN application No. 200710103147.3, filed on Apr. 27, 2007, titled �method and apparatus for allocating and processing sequences in wireless communication system�, CN application No. 200710112774.3, filed on Jun. 17, 2007, titled �method and apparatus for allocating and processing sequences in communication system�, and CN application No. 200710123676.X, filed on Sep. 30, 2007, titled �method and apparatus for allocating and processing sequences in communication system�, the contents of all of which are incorporated herein by reference.
FIELD OF THE APPLICATION The present application relates to the communication field, and in particular, to a technology for allocating and processing sequences in a communication system.
BACKGROUND OF THE APPLICATION In the communication system, the Constant Amplitude Zero Auto-Correlation (CAZAC) sequence is a very important communication resource. The specific features are as follows:
The modulo of the amplitude is a constant value, for example, normalized to 1; and
Zero periodical-auto-correlation: except the maximum correlation with the sequence itself, the auto correlation with other cyclic shift of this sequence is zero.
The CAZAC sequence has the above features. Therefore, after Fourier transformation, the sequence in the frequency domain is also a CAZAC sequence. The sequence of this feature may be used as a reference signal for channel estimation in the communication.
For example, in a Single Carrier Frequency Division Multiple Access (SC-FDMA) system, within a symbol time, the elements of the CAZAC sequence are transmitted sequentially on multiple sub-carriers. If the receiver knows the sequence of the transmitted signals, the receiver may perform channel estimation by using the received signals. The transmitted signals have equal amplitudes on every sub-carrier on the frequency domain. Therefore, the receiver may estimate out the channel fading on each sub-carrier fairly. In addition, due to the constant amplitude feature of the CAZAC sequence on the time domain, the peak-to-average value of the transmitted waveform is relatively low, which facilitates transmitting.
In another example, the random access preamble signals in the SC-FDMA system may be made of CAZAC sequences. The preamble sequence of the random access signals may be modulated on the frequency domain sub-carrier, and transformed onto the time domain through Fourier transformation before being transmitted. In this way, through high auto correlation and cross correlation of the CAZAC sequence, little interference exists between the random access preamble signals of different cells and different users.
A CAZAC signal is manifested as a CAZAC signal on both the time domain and the frequency domain. Therefore, the CAZAC signals may also be modulated directly into signals on the time domain that occupies certain bandwidth before being transmitted.
The CAZAC sequence comes in many types. A common type is Zadoff-Chu sequence. Other types include: Generalized Chirplike Sequence (GCL) and Milewski sequence. Taking the Zadoff-Chu sequence as an example, the generation mode or expression of a Zadoff-Chu sequence is as follows:
a r , N  ( k ) = { exp [ - j   2   π � r N  ( q � k + k � ( k + 1 ) 2 ) ] N   is   an   odd   number , k = 0 , 1 , �  , N - 1 exp [ - j   2   π � r N  ( q � k + k 2 2 ) ] N   is   an   even   number , k = 0 , 1 , �  , N - 1 Formula   ( 1 ) wherein r is a parameter generated by the sequence and is relatively prime to N, and q is an integer. When the value of r varies, the sequence differs. r is named as a basic sequence index, and q corresponds to different cyclic shifts. That is, the r value determines the basic sequence, and the q value determines different cyclic shifts of the same basic sequence. The sequence generated by different cyclic shifts of a sequence is known as a cyclic shift sequence generated by the same basic sequence. For two different r values such as r=u,r=v, when (u−v) is relatively prime to N, the two sequences are highly cross-correlated. When N is a prime number, r=1,2, . . . , N−1, and N−1 different CAZAC sequences are generated. Such sequences are highly cross-correlated. In the above example, when N is a prime number, the absolute value of cross correlation normalized between the two sequences is √{square root over (N)}. The conjugate of the Zadoff-Chu sequence is also a CAZAC sequence.
In a general cellular communication system, when a cell selects a sequence for modulation and transmission, another cell needs to select another sequence having the feature of low cross correlation. For example, in the case of using a Zadoff-Chu sequence, if N is a prime number, each cell selects a different r value, thus ensuring low cross correlation and low interference.
The modulated signals transmitted by a cell may also adopt the fragments of the old sequence or repeat cyclically, which also maintains the auto correlation and cross correlation features of the old sequence properly. Particularly, when the number of sub-carriers that bear the sequence in the cell is not a prime number, it is necessary to select the sequence whose length is equal to the prime number around the number of sub-carriers, and the desired sequences are obtained through segmentation or cyclic extension of the sequences before being transmitted. In the following description, the operations of segmentation or cyclic extension of the sequence are omitted.
When the signals of multiple sequences transmitted by different cells occupy the same time frequency resource, the sequences transmitted by cell A and cell B have the same length, as shown in FIG. 1. For example, two different Zadoff-Chu sequences whose length is a prime number N may be selected. When the basic sequence index of one sequence is different from that of the other, the two sequences are little correlated, and the transmitted signals of different cells are little mutual-interfering.
As shown in FIG. 2, when the signals of the modulated sequence occupy different time frequency resources, some users of cell A transmit sequence-modulated signals on the radio resource with bandwidth B1; meanwhile, some users of cell B transmit sequence-modulated signals on the radio resource with bandwidth B2, and the time frequency resources of the two parts overlap. In the system shown in FIG. 2, all cells have the same sub-carrier width. Within bandwidth B1, 36 sub-carriers exist. Within bandwidth B2, 144 sub-carriers exist. Because the sequence is mapped onto a sub-carrier, the length of the sub-carrier corresponds to the length of the sequence. Evidently, the two cells need to select sequences of different lengths respectively. In this case, the cross interference may be strong between the long sequence and the short sequence, and the sequence planning becomes relatively complex. In the example shown in FIG. 2, only sequences of two lengths exist. In practice, depending on the size of different radio resources occupied by a user's transmission, more sequences of different lengths may exist, and the complexity is higher.
The foregoing modulated signals of the sequences that occupy different time frequency resources occur frequently in the SC-FDMA system. Because the sequence serves as a reference signal and provides the channel estimation required by data demodulation, the sequence is transmitted along with the bandwidth resources of the data. The data bandwidth of the user may have different bandwidth values and locations at different times according to specific scheduling rules. Therefore, the sequence of the reference signal of each different cell occupies the time frequency resources in a way that is frequently changing, and the interference between cells is affected by the correlation of sequences of different lengths. To make matters worse, the system generally uses the shift correlation feature of sequences, obtains multiple code division quadrature sequences through different cyclic time shifts, and allocates them to different users. Therefore, once strong interference occurs between the sequences of two lengths, the users who use the sequences of the two lengths may interfere with each other strongly.
Nevertheless, the modes of the sequence occupying the time frequency resources are not limited to the foregoing examples. For example, sequences of different lengths may be modulated on the time domain at the same sampling frequency, which also brings the issue of correlation between the long sequence and the short sequence. Alternatively, the sequence may occupy the frequency domain sub-carriers at different sub-carrier intervals, or occupy the time sampling points at different time sampling intervals. In other words, the sequence is not modulated on all sub-carriers/sampling points, but modulated at regular intervals equivalent to a specific number of sub-carriers/sampling points.
To sum up, when the sequence occupies the time frequency resource in different modes, the interference among cells is relatively complex. Particularly, when sequences of different lengths exist, the sequences of each length need to be planned separately, and the interference among sequences with different length needs to be considered in a system with multiple cells.
SUMMARY OF THE APPLICATION An embodiment of the present application provides a method for allocating sequences in a communication system. The method includes:
dividing sequences in a sequence group into multiple sub-groups, where each sub-group corresponds to its own mode of occupying time frequency resources;
selecting sequences from a candidate sequence collection corresponding to each sub-group to form sequences in the sub-group in this way: the sequences in a sub-group i (i is a serial number of the sub-group) in a sequence group k (k is a serial number of the sequence group) are composed of n (n is a natural number) sequences in the candidate sequence collection, where the n sequences make the |ri/Ni−ck/Np 1 | or |(ri/Ni−ck/Np 1 ) modu mk,i| function value the smallest, second smallest, till the nth smallest respectively; Np 1 is the length of a reference sub-group sequence, ck is a basic sequence index of a sequence with a length of Np 1 determined by the sequence group k; ri is a basic sequence index in the candidate sequence collection, and Ni is the length of a sequence in the candidate sequence collection; mk,i is a variable dependent on the group number k and the sub-group number i; and
allocating the sequence groups to the cells, users or channels.
A method for processing sequences provided in an embodiment of the present application includes:
obtaining a group number k of a sequence group allocated by the system;
selecting n (n is a natural number) sequences from a candidate sequence collection to form sequences in a sub-group i (i is a serial number of the sub-group) in a sequence group k, where the n sequences make the |ri/Ni−ck/Np 1 | or |(ri/Ni−ck/Np 1 ) modu mk,i| function value the smallest, second smallest, till the nth smallest respectively, Np 1 is the length of a reference sub-group sequence, ck is a basic sequence index of a sequence with a length of Np 1 determined by the sequence group k; ri is a basic sequence index in the candidate sequence collection, and Ni is the length of a sequence in the candidate sequence collection; mk,i is a variable dependent on the group number k and the sub-group number i; and
generating a corresponding sequence according to the sequences in the formed sub-group, and transmitting or receiving the sequences on the time frequency resources corresponding to the sub-group i.
An apparatus for processing sequences provided in an embodiment of the present application includes:
a sequence selecting unit, adapted to: obtain a group number k of a sequence group allocated by the system, and select n (n is a natural number) sequences from a candidate sequence collection to form sequences in a sub-group i (i is a serial number of the sub-group) in the sequence group k (k is a serial number of the sequence group), where the n sequences make the |ri/Ni−ck/Np 1 | or |(ri/Ni−ck/Np 1 ) modu mk,i| function value the smallest, second smallest, and the nth smallest respectively, Np 1 is the length of a reference sub-group sequence, ck is a basic sequence index of a sequence with a length of Np 1 determined by the sequence group k; ri is a basic sequence index in the candidate sequence collection, and Ni is the length of a sequence in the candidate sequence collection; mk,i is a variable dependent on the group number k and the sub-group number i; and
a sequence processing unit, adapted to: generate a corresponding sequence according to the sequences in the formed sub-group i, and process the sequences on the time frequency resources corresponding to the sub-group I, where the processing includes transmitting and receiving.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows the conventional art where the sequences transmitted by different cells occupy the same time frequency resources and have the same length;
FIG. 2 shows the conventional art where the sequences transmitted by different cells occupy partially overlapped time frequency resources and have different lengths;
FIG. 3 shows a calculation process for determining u and v in an embodiment of the present application;
FIG. 4 is a flowchart of a sequence processing method in an embodiment of the present application;
FIG. 5 shows a structure of a sequence processing apparatus in an embodiment of the present application;
FIG. 6 shows a structure of a sequence processing apparatus in an embodiment of the present application; and
FIG. 7 shows a structure of a sequence processing apparatus in another embodiment of the present application.
DETAILED DESCRIPTION OF THE APPLICATION A detailed description of the present application is provided hereunder with reference to accompanying drawings and preferred embodiments.
In the Chinese application No. 200610173364.5, which was filed with the State Intellectual Property Office of the People's Republic of China by Huawei Technologies Co., Ltd. on Dec. 30, 2006, a method is provided to overcome the sequence interference caused by different modes of occupying time frequency resources by grouping sequences. The method shows: the sequences in a group are multiple sequences corresponding to different modes of occupying time frequency resources; the strongly correlated sequences are included into a group, and the correlation between different groups is relatively low; and then the sequence groups are allocated among the cells. The strongly correlated sequences are in the same group, and the sequences in the same group are used only in this group. The sequence groups used by different cells are little correlated with each other, thus avoiding strong correlation in the case of using sequences of different lengths in different cells.
The strongly correlated sequences are included into a group. Generally, the composition of all sequences of each group may be stored. When a cell user or channel wants to use a sequence corresponding to a mode of occupying time frequency resources in the allocated sequence group, the desired sequence may be found in the stored sequence group. However, the formation of the sequence group needs a pre-stored table. If the size of the sequence group becomes greater, the storage occupies a huge space, and the searching is time-consuming. The extra storage increases the complexity and wastes hardware resources.
Embodiment 1 In this embodiment, the system allocates sequence groups to the cell, user or channel. The sequences in each sequence group are divided into multiple sequence sub-groups. Each sequence sub-group corresponds to a mode of occupying time frequency resources. In the communication system, each mode of occupying time frequency resources corresponds to a sequence sub-group uniquely. The sequences in each sub-group are selected from the candidate sequence collection corresponding to the sub-group in a specific selection mode. According to the allocated sequence group and the mode of occupying time frequency resources used for the specific transmit signals, the user or channel selects the sequences in the sequence sub-group corresponding to the mode of occupying the time frequency resources of the transmit signals in the allocated sequence group for transmitting or receiving.
A certain selection mode can be: for a random sub-group i, determining a function �i(�) corresponding to the sub-group, where the domain of the function is the candidate sequence collection corresponding to the sub-group; determining n sequences from the candidate sequence collection to form sequences, n is a natural number, in the sub-group i, i is a serial number of the sub-group, in the sequence group k, k is the serial number of the sequence group, where the n sequences make the �i(�) function value the smallest, second smallest, and third smallest respectively, d(a,b) is a two variables function, and Gk is a variable determined by the group number k. This selection mode is equivalent to: selecting n sequences from the candidate sequence collection to make the d(�i(�), Gk) of all other sequences greater than d(�i(�), Gk)) of these n sequences.
The foregoing sequence selection mode is described below, taking a Zadoff-Chu sequence, namely, ar,N(z), in the CAZAC sequence as an example:
Each sequence group is composed of M sub-groups. The candidate sequence collection of sub-groups 1,2, . . . , M includes the Zadoff-Chu sequences whose lengths are N1, N2, . . . , NM. The Zadoff-Chu sequence whose length is Ni, namely, the ar i ,N i (z), z=0,1, . . . , Ni−1 sequence, has Ni−1 different basic sequences, depending on ri=1,2, . . . , Ni−1. Specifically, the function corresponding to the sub-group i (namely, the sub-group i corresponding to the Zadoff-Chu sequence whose length is Ni) is �i: {ar i ,N i (z)}z=0,1,2, . . . , N i −1→ri/Ni. The domain of this function is a candidate sequence collection corresponding to the sub-group i. ri is an index of the Zadoff-Chu sequence in the candidate sequence collection, and Ni is the length of the Zadoff-Chu sequence in the candidate sequence collection.
For the sequence group k=1,2, . . . , the sub-group numbered p1 is selected as a reference sub-group. The foregoing Gk is defined as Gk=�p 1 ({ac k ,N p1 (z)}z=0,1, . . . , N 1 −1)=ck/Np 1 , Np 1 is the length of the reference sub-group sequence, and ck is a basic sequence index of the sequence with a length of Np 1 determined by the sequence group k. Particularly, if ck=k is selected, then Gk=�p 1 ({ak,N p1 })=k/Np 1 .
If the foregoing function d(a,b) is defined as |a−b|, the sequence that makes the d(�p 1 (�), Gk))=d(�p 1 (�), �p 1 ({ak,N p1 })) value the smallest in the sub-group numbered p1 in the sequence group k is the {ak,N p1 } sequence with the index of rp 1 =k and length of Np 1 . In this case, d(�p 1 (�), Gk)=0.
The sequences in the sub-group i=m in the sequence group k are n sequences that have the length of Nm and make the |rm/Nm−k/Np 1 | value the smallest, second smallest, and third smallest respectively, namely, n sequences that make the d(�m(�), �p 1 ({ak,N p1 }) value smaller, where n is a natural number dependent on k and m.
The foregoing embodiment reveals that: the sequences (for example, i=m, j=p1) in at least two sub-groups i and j in at least one sequence group k are n (n is a natural number dependent on k, i, and j) sequences selected from the candidate sequence collection and make the value of the function d(�i(�), �j(�)) such as the foregoing d(�m(�), �p 1 ({ak,N p1 }) smallest, second smallest, and third smallest respectively.
This embodiment is introduced below, taking a non-CAZAC sequence such as a Gauss sequence which has high auto correlation and cross correlation features as an example. A formula for generating a Gauss sequence is:
b α 1 ,α l−1 , . . . , α 0 (n)=exp(−2πj(αl n l+αl−1 n l−1+ . . . +α0)), n=0,1,2, . . . , N Formula (2)
In formula (2), nl is the highest-order item of the Gauss sequence, l is the highest order, and the value range of l is a positive integer. If l=2, α2=r/N, where N is a positive integer. If N=2N1 and α1=r(N1 mod 2)/N+2r/N�p, the Gauss sequence is equivalent to a Zadoff-Chu sequence αr,N 1 (n) w hose indexes are r,N1. if l>2, different αl=r/(Nl), r=1,2, . . . , N−1 values correspond to different Gauss sequence groups, and each group has multiple sequences which depend on the lower-order coefficients αl−1, αl−2, . . . . In this case, the Gauss sequence is not a CAZAC sequence, but has high auto correlation and cross correlation features. In this embodiment, ar,N(n) is used to represent multiple sequences bα 1 ,α l−1 , . . . , α 0 (n) of αl=r/(lN). One of such sequences is defined as a basic sequence.
For a Gauss sequence αr,N(z), the function corresponding to the sub-group i may be defined as �i:{ar i ,N i (z)}z=0,1,2, . . . , N i −1→ri/Ni. The domain of this function is a candidate sequence collection corresponding to the sub-group i. In the function, ri is an index of the Gauss sequence in the candidate sequence collection, and Ni is the length of the Gauss sequence in the candidate sequence collection.
The function d(a,b) corresponding to the Gauss sequence may be d(a,b)=|(a−b) modu 1|, where the modu 1 operation is defined as making the modulo value included in (−�, �]
Particularly, for the Zadoff-Chu sequence which can be construed as a special example of the Gauss sequence, if the basic sequence index is r=−(N−1)/2, . . . , −1,0,1, . . . , (N−1)/2 because |a−b|<� the modu 1 operation is not required.
However, for general Gauss sequences such as r=1,3,5, . . . , N1−2, N1+2, . . . , 2N1−1, N=2N1, l=2, α2=r/(2N1), α1=0, and ar,N(z)z=−(N 1 −1)/2, . . . , −1,0,1,2, . . . , (N 1 −1)/2, d(a,b)=|(a−b) modu 1| is required. In other words, d(�i, �j) of the sequences corresponding to α2=ri/(2Ni) and the sequences corresponding to α2=rj/(2Nj) is
d  ( f i , f j ) =  r i / N i - r j / N j   modu   1  =  ( r i  N j - r j  N i )   modu   N i  N j N i  N j  , where the modu NiNj operation is defined as making the modulo value included in (−NiNj/2, NiNj/2] If l=3 and d(�i, �j) of the sequences corresponding to α3=ri/(3Ni) and the sequences corresponding to α3=rj/(3Nj) is d(�i,�j)=|(ri/Ni−rj/Nj)modu 1| and l=4,5, . . . , the processing is similar.
The Gauss sequence may be defined in another way. If αl=ri/N, and αr i ,N is used to represent the corresponding Gauss sequence, then the foregoing �i of the function is defined as �i: ar i ,N i (Z)→ri/Ni, and the function d(a,b) is defined as d(a,b)=|(a−b) modu 1/l|, where the modu 1/l operation makes −1(2l)<(a−b) modu 1/l≦1(2l). Therefore, the definition of the two types of Gauss sequences generates the same sequence group. The definition of such a measurement function is also applicable to the Zadoff-Chu sequence.
In another embodiment, if the mode of occupying time frequency resources is that the sequence is modulated on the radio resource whose sub-carrier interval (or time domain sampling interval) is s, then the function corresponding to the sub-group with the interval s is: �N i : {as 2 r i ,N i (z)}z=0,1,2, . . . , N i −1→ri/Ni, where s is the sub-carrier (or time domain sampling) interval of the radio resource. For a Gauss sequence, the function is �N i :{as l r i ,N i (z)}z=0,1,2, . . . , N i −1→ri/Ni, where l is the highest order of the Gauss sequence.
The foregoing reference sub-group is set according to multiple factors. A sub-group of a specific sequence length may be selected as a reference sub-group. Preferably, the sub-group with the minimum sequence length in the system is selected as a reference sub-group. The quantity of available sequence groups in the system is the same as the quantity of sequences of this length. Therefore, shorter sequences do not appear repeatedly in different sequence groups. For example, supposing the shortest sequence length according to the resource occupation mode is 11 in the system, then in the foregoing method, Np 1 =N1=11. In this case, 10 sequence groups are available in the system.
Alternatively, the sub-group with the maximum sequence length in the sequence group may be selected as a reference sub-group. For example, the maximum sequence length in the sequence group is 37, and a sub-group with the sequence length 37 is selected as a reference sub-group. In this case, Np 1 =N2=37, and 36 sequence groups are available. When r2 meets −1/(2N1)<r2/N2<1/(2N1), if the value of r1 is not limited to r1=1,2, . . . , N1−1, then r1 that makes the |r2/N2−r1/N1| value the smallest is 0. In practice, the value 0 of r1 does not correspond to the Zadoff-Chu sequence. Therefore, r2 that makes −1/(2N1)<r2/N2<1/(2N1), namely, r2=+1,−1, may be removed. In this way, there are 34 groups of sequences in total. In a sequence group, the quantity of the shortest sequences is less than 36. Therefore, the shortest sequences are used repeatedly.
Moreover, the reference sub-group may be a default sub-group of the system, and may be set by the system as required and notified to the user. After a sequence in the reference sub-group j is selected, the sequences in the sub-group i are n sequences that make the d(�i(�), �j(�)) value smaller, and are in the sequence group that contain the sequences selected for the reference sub-group j. Different sequence groups are generated by selecting different sequences of the reference sub-group j.
The sequence group formed in the above method is described below through examples.
There are 3 sub-groups in total in this embodiment. The sequence candidate collection includes Zadoff-Chu sequences whose lengths are 11, 23 and 37 respectively, corresponding to three resource occupation modes. If Np 1 =N1=11 is selected, then there are 10 sequence groups in total. By selecting the sequences that make the absolute value of (rm/Nm−r1/N1) the smallest and including them into each sequence group, where each sub-group contains only one sequence and the sequence is represented by a basic sequence index, the following table is generated:
N3 = 37
Index r2 Index r3 1
The foregoing grouping method makes the absolute value of rm/Nm−r1/N1=(N1rm−Nmr1)/(N1Nm) the smallest, namely, makes the absolute value of N1rm−Nmr1 the smallest. That is, the method ensures high correlation between sequences. As verified, the correlation between the sequences in each sequence group in Table 1 is very high.
In the foregoing embodiment, selection of the n sequences comes in two circumstances:
Preferably, n is 1, namely, in the foregoing example, a sequence that makes (rm/Nm−k/N1) the smallest is selected and included into a sub-group m.
Preferably, n is a natural number greater than 1, and the value of n depends on the length difference between sub-group Nm and reference sub-group N1. The sequences corresponding to several basic sequence indexes near rm that makes (rm/Nm−k/N1) the smallest are included into a sub-group. Generally, such sequences are n sequences closest to the minimum rm, where n depends on the length difference between N1 and Nm.
For example, if Nm is about 4�N1, two rm's may be included into the group. Generally, n=┌Nm/(2N1)┐ may be selected. In an example, n=└Nm/N1┘ may be selected, where └z┘ is the maximum integer not greater than z. In the sequence sub-group in this case, there may be more than one sequence of a certain length. After such allocation in the system, when using the sequence, the user may select any of the allocated n sequences for transmitting, for example, select the sequence that makes (rm/Nm−k/N1) the smallest, second smallest, and so on.
When two Zadoff-Chu sequences of different lengths are highly correlated, it is sure that |rm/Nm−r1/N1| is relatively small. In the foregoing allocation method, it is ensured that the value of |ri/Ni−rj/Nj| between two sub-groups i, j of different groups is great. Therefore, the sequences are little correlated between different groups, and the interference is low. Further, among the sequences of certain lengths, some may be selected for allocation, and the remaining are not used in the system. This prevents the sequences the second most correlated with the sequences in the reference sub-group from appearing in other sequence groups, and reduces strong interference.
If the foregoing function d(a,b) is defined as |(a−b) modu mk,i|, where modu mk,i causes the value of the function d(a,b) after this operation to be included in (−mk,i/2, mk,i/2], and mk,i is a variable determined by the group number k and sub-group number i, then mk,i=1/B, where B is a natural number, namely, mk,iε{1, �, ⅓, �, . . . }.
The foregoing sequence allocation mode is described below, taking a Zadoff-Chu sequence, namely, ar,N(z), in the CAZAC sequence as an example:
For the sequence group k=1,2, . . . , the sub-group numbered p1 is selected as a reference sub-group. The foregoing Gk is defined as Gk=�p 1 ({aw k ,N p1 (z)}z=0,1, . . . , N 1 −1)=wk/Np1, Np 1 is the length of the reference sub-group sequence, and wk is a basic sequence index of the sequence with a length of Np 1 determined by the sequence group k. Particularly, if wk=k is selected, then Gk=�p 1 ({ak,N p1 })=k/Np 1 . Therefore, the sequence that makes the d(�p 1 (�), Gk)=d(�p 1 (�), �p 1 (ak,N p1 })) value the smallest in the sub-group numbered p1 in the sequence group k is the {ak,N p1 } sequence with the index of rp 1 =k and length of Np 1 . In this case, d(�p 1 (�), Gk)=0.
The sequences in the sub-group i=q in the sequence group k are n sequences that have the length of Nq and make the |(rq/Nq−k/Np 1 ) modu mk,q| value the smallest, second smallest, and third smallest respectively, namely, n sequences that make the d(�p 1 (�), �p 1 ({ak,N p1 })) value the smallest.
It should be noted that the foregoing function d(a,b)=|(a−b) modu mk,i| may vary between different sequence groups, or different sub-groups of the same sequence group. For example, all sub-groups of one sequence group adopt a d(a,b) function, and all sub-groups of another sequence group adopt another d(a,b) function. Alternatively, one sub-group adopts a d(a,b) function, and another sub-group may adopt another d(a,b) function. Specifically, mk,i in the function has different values, which give rise to different measurement functions.
The sequence group formed in the foregoing method is described below through examples.
There are 3 sub-groups in total in this embodiment. The sequence candidate collection includes Zadoff-Chu sequences whose lengths are 31, 47 and 59 respectively, corresponding to three resource occupation modes. If Np 1 =N1=31 is selected, then there are 30 sequence groups in total. By using mk,q in Table 2 and selecting the sequences that make |(rq/Nq−k/N1) modu mk,q| the smallest and including them into each sequence group, where each sub-group contains only one sequence and the sequence is represented by a basic sequence index, Table 3 is generated:
N2 = 47
N3 = 59
mk,2 mk,3 1
The following grouping method makes |(rq/Nq−k/N1) modu mk,q| smallest. As verified, all the sequences in Table 3 are the sequences the most correlated with the sequences in the reference sub-group of the same sequence group. Therefore, the correlation of the sequences between different groups is further reduced, and the inter-group interference is weaker.
When the number of sub-carriers that bear the sequence in the cell is not a prime number, it is necessary to select the sequence whose length is equal to the prime number around the number of sub-carriers, and the desired sequence is obtained through sequence segmentation or cyclic extension of the sequence before being transmitted.
The following description takes cyclic extension as an example. In this embodiment, there are quantities of sub-carriers that bear the sequences: 36, 48, and 60. The sequences with a length of the maximum prime number less than the quantity of sub-carriers, namely, the Zadoff-Chu sequences corresponding to the lengths 31, 47 and 59, are selected, and the desired sequences are obtained through cyclic extension of such sequences. If Np 1 =N1=31 is selected, then there are 30 sequence groups in total. By using mk,q in Table 4 and selecting the sequences that make |(rq/Nq−k/N1) modu mk,q| the smallest and including them into each sequence group, where each sub-group contains only one sequence and the sequence is represented by a basic sequence index, Table 5 is generated:
mk,2 Number K
mk,2 mk,3 Number K
mk,3 1
The following grouping method makes |(rq/Nq−k/N1) modu mk,q| the smallest. As verified, all the sequences in Table 5 are the sequences the most correlated with the sequences in the reference length of the same sequence group. Therefore, the correlation of sequences between different groups is further reduced, and the inter-group interference is weaker.
The specific value of mk,q may be: if Nq≧Lr, then mk,q=1, where Nq is the sequence length of the sub-group q, and Lr is determined by the reference sub-group sequence length Np 1 . Specifically, for Np 1 =N1=−31, Lr=139. If Nq=139 or above, then mk,q=1. After cyclic extension of the sequence, Lr=191. Therefore, when Nq=191 or above, mk,q=1.
Preferably, n is 1, namely, in the foregoing example, a sequence that makes |(rq/Nq−k/N1) modu mk,q| the smallest is selected and included into the sub-group q.
Preferably, n is a natural number greater than 1, and the value of n depends on the length difference between sub-group Nq and reference sub-group N1. The sequences corresponding to several basic sequence indexes near rq that makes |(rq/Nq−k/N1) modu mk,q| the smallest are included into a sub-group. Generally, such sequences are n sequences closest to the minimum rq, where n depends on the length difference between N1, Nq. For example, if Nq is about 4�N1, two rq's may be included into the group. Generally, n=|Nq/(2N1)| may be selected, where ┌z┐ is the minimum integer greater than z. In another example, n=└Nq/N1┘ may be selected, where └z┘ is the maximum integer not greater than z. In the sequence sub-group in this case, there may be more than one sequence of a certain length. After such allocation in the system, when using the sequence, the user may select any of the allocated n sequences for transmitting, for example, select rq=� that makes |(rq/Nq−k/N1) modu mk,q| the smallest, then the fewer n sequences are ��1, ��2, . . . . The transmitter and the receiver may obtain the data through calculation in this way rather than store the data.
When two Zadoff-Chu sequences of different lengths are highly correlated, it is sure that |(rq/Nq−r1/N1) modu mr 1 ,q| is relatively small. In the foregoing allocation method, it is ensured that the value of i,j between two sub-groups |(ri/Ni−rj/Nj) modu mr j ,i| of different groups is great. Therefore, the sequences are little correlated between different groups, and the interference is low. Further, among the sequences of certain lengths, some may be selected for allocation, and the remaining are not used in the system. This prevents the sequences the second most correlated with the sequences in the reference sub-group from appearing in other sequence groups, and reduces strong interference between groups.
In other embodiments, the definition of the foregoing function d(a,b) may also
be   d  ( a , b ) = {  a - b  , when   u ≤ ( a - b ) ≤ v infinity , others , or   d  ( a , b ) = {  ( a - b )  modu   m k , i  , when   u ≤ ( a - b )  modu   m k , i ≤ v infinity , others . The infinity in the definition of the d(a,b) function filters out certain sequences, and ensures low correlation between different groups.
It should be noted that the foregoing function
d  ( a , b ) = {  a - b  , when   u ≤ ( a - b ) ≤ v infinity , others   d  ( a , b ) = {  ( a - b )  modu   m k , i  , when   u ≤ ( a - b )  modu   m k , i ≤ v infinity , others or may vary between different sequence groups, or different sub-groups of the same sequence group. For example, all sub-groups of one sequence group adopt a d(a,b) function, and all sub-groups of another sequence group adopt another d(a,b) function. Alternatively, one sub-group adopts a d(a,b) function, and another sub-group may adopt another d(a,b) function.
Specifically, u,v in the function has different values, which give rise to different measurement functions. For example, u=0, v=+∞, or u=−∞, v=0, or u=−1/(2�11)+1/(23�4), v=1/(2�11)−1/(23�4) or u=a, v=b, where a,b depend on the sequence group k and sub-group i, and so on.
Specifically, in the foregoing embodiment of �i: {ar i ,N i (z)}z=0,1,2, . . . , N i −1→ri/Ni, if
d  ( a , b ) = {  a - b  , when   u ≤ ( a - b ) ≤ v infinity , others , this embodiment is: selecting the sequences that meet u≦(ri/Ni−k/Np 1 )≦v and including them into each sequence group; |ri/Ni−rj/Nj|>1/Ci is met between any two sequences of different sequence groups, where Ni<Nj, as detailed below:
First, u=0, v=+∞ or, u=−∞, v=0, namely, the sequences that make the value the smallest in a single direction. For the positive direction, it is equivalent to selecting the sequences that meet (rm/Nm−k/Np 1 )≧0; for the negative direction, it is equivalent to selecting the sequences that meet (k/Np 1 −rm/Nm)≧0. For example, if the sub-group length is Nm, the positive result closest to k/Np 1 is rm with the difference of 0.036, and the negative result closest to k/Np 1 is r′m with the difference of −0.025. The one the most correlated with the rp 1 =k sequence of a length of Np 1 is r′m. If the system specifies that the sequence in the positive direction of (rm/Nm−k/Np 1 ) needs to be selected, rm is selected. The benefit is: after the sequences of various lengths are compared with k/Np 1 , the difference between the function values, namely, |ri/Ni−rj/Nj|, is smaller.
Secondly, u=−1/(2Np 1 )+1/(4Np 2 ) and v=1/(2Np 1 )−1/(4Np 2 ) may be selected. The length (Np 1 ) of the reference sequence is the shortest sequence length and Np 2 is the sequence length only greater than Np 1 . Here is an example:
In this embodiment, there are 4 sub-groups in total. The candidate sequence collections contain Zadoff-Chu sequences with N1=11, N2=23, N3=37,and N4=47 respectively. By selecting the sequences that meet |ri/Ni−k/N1|<1/(2N1)−1/(4N2), namely, |ri/Ni−k/N1|<1/(2�11)−1/(4�23) and including them into the sub-groups of each sequence group, the following table is generated, where the sequence is represented by a basic sequence index:
N4 = 47
Group Number K
In table 6, |ri/Ni−rj/Nj|>1/(2Ni) is met between any two sequences of different sequence groups, where Ni<Nj. In this way, the correlation between the two sequences is relatively lower.
Thirdly, for different sequence groups k and different sub-groups i in the same sequence group, u, v may differ.
The shortest sequence is selected as a reference sequence. Therefore, Np 1 represents the length of the shortest sequence, and Np L represents the length of the longest sequence; the sequence group that includes the basic sequence with a length of Np 1 and an index of 1 is numbered �q1�; the sequence group that includes the basic sequence with a length of Np 1 and an index of Np 1 −1 is numbered �qN p1 −1�; the sequence group that includes the basic sequence with a length of Np 1 and an index of k is numbered �qk�; the sequence group that includes the basic sequence with a length of Np 1 and an index of k+1 is numbered �qk+1�; the sub-group that includes the basic sequence with a length of Np 1 is numbered �p1�; the sub-group that includes the basic sequence with a length of Np m is numbered �pm�; the sub-group that includes the basic sequence with a length of Np i−1 is numbered �pi−1�; and the sub-group that includes the basic sequence with a length of Np i is numbered �pi�, where Np i−1 <Np i .
Step 1001: For the sub-group p1 of the sequence group q1, uq 1 ,p 1 −1/(2Np 1 )+δu, where 1/NpL−1/Np 1 +1/(2Np1)≦δu<�(Np 1 ).
vq k ,p 1 of the sub-group p1 of the sequence group qk and uq k+1 ,p 1 of the sub-group p1 of the sequence group qk+1 (k=1, . . . , Np 1 −2) are:
v q k ,p 1 =1/D, u q k+1 ,p 1 =−1/D, where 1/D≦1/(2N p 1 ).
Step 1002: As shown in FIG. 3, vq k ,p i of the sub-group pi of the sequence group qk and uq k+1 ,p i of the sub-group pi of the sequence group qk+1 (k=1, . . . , Np 1 −2, iεS) are:
rightq k ,p i−1 =v q k ,p i−1 +k/N p 1 , leftq k+1 ,p i−1 =u q k+1 ,p i−1 +(k+1)/N p 1 For the basic sequence with a length of Np i−1 , depending on the value of rp i−1 , rq k+1 ,p i−1 that meets rp i−1 /Np i−1 −leftq k+1 ,p i−1 ≧0 and minimum |rp i−1 /Np i−1 −leftq k+1 ,p i−1 | is obtained, namely, the obtained basic sequence rq k+1 ,p i−1 is included in the sequence group qk+1, has a length of Np i−1 and is closest to the left border (leftq k+1 , p i−1 ) of the sequence group qk+1.
If rq k+1 ,p i−1 /Np i−1 −1/Cp i−1 −rightq k ,p i−1 ≧0, namely, rq k+1 ,p i−1 /Np i−1 −1/Cp i−1 is less than the right border (rightq k ,p i−1 ) of the sequence group qk, then vq k ,p i =vq k ,p i−1 +rq k+1 ,p i−1 /Np i−1 −1/Cp i−1 −rightq k ,p i−1 , to ensure low cross correlation between the sequence group qk and its adjacent sequence group qk+1; if rq k+1 ,p i−1 /Np i−1 −1/Cp i−1 −rightq k ,p i−1 >0, namely, rq k+1 ,p i−1 /Np i−1 −1/Cp i−1 is greater than the right border (rightq k ,p i−1 ) of the sequence group qk, then vq k ,p i =vq k ,p i−1 .
For the basic sequence with a length of Np i−1 , depending on the value of rp i−1 , rq k ,p i−1 that meets rp i−1 /Np i−1 −rightq k ,p i−1 ≧0 and minimum |rp i−1 /Np i−1 −rightq k ,p i−1 | is obtained, namely, the obtained basic sequence qk is included in the sequence group Np i−1 , has a length of qk and is closest to the right border (rightq k ,p i−1 ) of the sequence group rq k ,p i−1 .
If rq k ,p i−1 /Np i−1 +1/Cp i−1 −leftq k+1 ,p i−1 ≧0 namely, rq k ,p i−1 /Np i−1 +1/Cp i−1 is greater than the left border (qk+1) of the sequence group leftq k+1 ,p i−1 , then uq k+1 ,p i =uq k+1 ,p i−1 +rq k ,p i−1 /Np i−1 +1/Cp i−1 −leftq k+1 ,p i−1 , to ensure low cross correlation between the sequence group qk and its adjacent sequence group qk+1; if rq k ,p i−1 /Np i−1 +1/Cp i−1 −leftq k+1 ,p i−1 <0, namely, rq k ,p i−1 /Np i−1 +1/Cp i−1 is less than the left border (qk+1) of the sequence group leftq k+1 ,p i−1 , then uq k+1 ,p i =uq k+1 ,p i−1 .
qN p1 −1 of the sub-group pi of the sequence group vqN p1 −1,p i and q1 of the sub-group pi of the sequence group uq 1 ,p i (iεS) are:
rightqN p1 −1,p i−1 =v qN p1 −1,p i−1 +(N p 1 −1)/N p 1 , leftq 1 ,p i−1 =u q 1 ,p i−1 +1/N p 1 rightqN p1 −1,p i−1 ′=v qN p1 −1,p i−1 −1/N p 1 , leftq 1 ,p i−1 ′=u q 1 ,p i−1 +(N p 1 +1)/N p 1 For the basic sequence with a length of Np i−1 , depending on the value of rp i−1 , rq 1 ,p i−1 that meets rp −1 /Np i−1 −leftq 1 ,p i−1 ≧0 and minimum |rp i−1 /Np i−1 −leftq 1 ,p i−1 | is obtained;
If rq 1 ,p i−1 /Np i−1 −1/Cp i−1 −rightq Np1 −1,p i−1 ′≦0, then vqN p1 −1,p i =vqN p1 −1,p i−1 +rq 1 ,p i−1 /Np i−1 −1/Cp i−1 −rightqN p1 −1,p i−1 ′; if rq 1 ,p i−1 /Np i−1 −1/Cp i−1 −rightqN p1 −1,p i−1 ′>0, then vqN p1 −1,p i =vqN p1 −1,p i−1 ;
For the basic sequence with a length of Np i−1 , depending on the value of rp i−1 , rqN p1 −1,p i−1 that meets rp i−1 /Np i−1 −rightqN p1 −1,p i−1 ≦0 and minimum |rp i−1 /Np i−1 −rightqN p1 −1,p i−1 | is obtained;
If rqN p1 −1,p i−1 /Np i−1 +1/Cp i−1 −leftq 1 ,p i−1 ′≧0, then uq 1 ,p i =uq 1 ,p i−1 +rqN p1 −1,p i−1 /Np i−1 +1/Cp i−1 −leftq 1 ,p i−1 ′; if rqN p1 −1,p i−1 /Np i−1 +1/Cp i−1 −leftq 1 ,p i−1 ′<0, then uq 1 ,p i =uq 1 ,p i−1 ;
Particularly, Cp i−1 =2Np i−1 .
Step 1003: uq k ,p i and vq k ,p i of the sub-group pi in the sequence group qk (k=1, . . . , Np 1 −1, iεI−S) are:
uq k ,p i =uq k ,p m and vq k ,p i =vq k ,p m , respectively
where I and S are two index collections; in the collection I={2,3 . . . , L}, L is the quantity of sequence lengths in a candidate sequence collection, and the collection S is the collection I or a sub-collection of the collection I, and m is an element with the maximum value in the collection S.
In the following example, δu=0, δv=0, D=2Np 1 , Cp i−1 =2Np i−1 , qk=k and pi=i.
Example 1 In this example, there are 4 sub-groups in total. The candidate sequence collection contains the Zadoff-Chu are sequences with N11=11, N2=23, N3=37, and N4=47 respectively. Taking the fourth sequence group as an example (namely, k=4), v4,i and u5,i iε{1,2,3,4} are obtained through step 1101, specifically:
For the sub-group 1, v4,1=1/(2�11), u5,1=−1/(2�11).
For the sub-group 2, right4,1=v4,1+4/11=1/(2�11)+4/11, left5,1=u5,1+5/11=−1/(2�11)+5/11; because no r5,1 or r4,1 compliant with the conditions exists, v4,2=v4,1, namely, v4,2=1/(2�11); u5,2=u5,1, namely, u5,2=−1/(2�11).
For the sub-group 3, right4,2=v4,2+4/11=1/(2�11)+4/11, left5,2=u5,2+5/11=−1/(2�11)+5/11.
For N2=23, when r2 varies, if r5,2=10, then r5,2/N2−left5,2>0 and |r5,2/N2−left5,2| is the minimum value; because r5,2/N2−�(N2)−right4,2>0, v4,3=v4,2, namely, v4,3=1(2�11).
For N2=23, when r2 varies, if r4,2=9 then r4,2/N2−right4,2<0 and |r4,2/N2−right4,2| is the minimum value; because r4,2/N2+1/(2N2)−left5,2>0,
u 5 , 3 =  u 5 , 2 + r 4 , 2 / N 2 + 1 / ( 2   N 2 ) - left 5 , 2 =  - 1 / ( 2 � 11 ) + 9 / 23 + 1 / ( 2 � 23 ) - ( - 1 / ( 2 � 11 ) + 5 / 11 ) =  - 21 / ( 2 � 11 � 23 ) . For the sub-group 4, right4,3=v4,3+4/11=1/(2�11)+4/11, left5,3=u5,3+5/11=−21/(2�11�23)+5/11.
For N3=37, when r3 varies, if r5,3=16, then r5,3/N3−left5,3>0 and |r5,3/N3−left5,3| is the minimum value; because r5,3/N3−1/(2N3)−right4,3>0, v4,4=v4,3, namely, v4,4=1/(2�11).
For N3=37, when r3 varies, if r4,3=15, then r4,3/N3−right4,3<0 and |r4,3/N3−right4,3| is the minimum value; because r4,3/N3+1/(2N3)−left5,3>0,
u 5 , 4 =  u 5 , 3 + r 4 , 3 / N 3 + 1 / ( 2   N 3 ) - left 5 , 3 =  - 21 / ( 2 � 11 � 23 ) + 15 / 37 + 1 / ( 2 � 37 ) -  ( - 21 / ( 2 � 11 � 23 ) + 5 / 11 ) =  - 29 / ( 2 � 11 � 37 ) . By analogy, u and v of all sub-groups of all sequence groups are obtained, and the following table is generated:
u1,1 = −1/(2 � 11)
u1,2 = −1/(2 � 11)
u1,3 = −1/(2 � 11)
u1,4 = −1/(2 � 11)
v1,1 = 1/(2 � 11)
v1,2 = 1/(2 � 11)
v1,3 = 1/(2 � 11)
v1,4 = 1/(2 � 11)
u2,1 = −1/(2 � 11)
u2,2 = −1/(2 � 11)
u2,3 = −15/(2 � 11 � 23)
u2,4 = −15/(2 � 11 � 23)
v2,1 = 1/(2 � 11)
v2,2 = 1/(2 � 11)
v2,3 = 1/(2 � 11)
v2,4 = 1/(2 � 11)
u3,1 = −1/(2 � 11)
u3,2 = −1/(2 � 11)
u3,3 = −17/(2 � 11 � 23)
u3,4 = −17/(2 � 11 � 23)
v3,1 = 1/(2 � 11)
v3,2 = 1/(2 � 11)
v3,3 = 1/(2 � 11)
v3,4 = 1/(2 � 11)
u4,1 = −1/(2 � 11)
u4,2 = −1/(2 � 11)
u4,3 = −19/(2 � 11 � 23)
u4,4 = −19/(2 � 11 � 23)
v4,1 = 1/(2 � 11)
v4,2 = 1/(2 � 11)
v4,3 = 1/(2 � 11)
v4,4 = 1/(2 � 11)
u5,1 = −1/(2 � 11)
u5,2 = −1/(2 � 11)
u5,3 = −21/(2 � 11 � 23)
u5,4 = −29/(2 � 11 � 37)
v5,1 = 1/(2 � 11)
v5,2 = 1/(2 � 11)
v5,3 = 1/(2 � 11)
v5,4 = 1/(2 � 11)
u6,1 = −1/(2 � 11)
u6,2 = −1/(2 � 11)
u6,3 = −1/(2 � 11)
u6,4 = −1/(2 � 11)
v6,1 = 1/(2 � 11)
v6,2 = 1/(2 � 11)
v6,3 = 21/(2 � 11 � 23)
v6,4 = 29/(2 � 11 � 37)
u7,1 = −1/(2 � 11)
u7,2 = −1/(2 � 11)
u7,3 = −1/(2 � 11)
u7,4 = −1/(2 � 11)
v7,1 = 1/(2 � 11)
v7,2 = 1/(2 � 11)
v7,3 = 19/(2 � 11 � 23)
v7,4 = 19/(2 � 11 � 23)
u8,1 = −1/(2 � 11)
u8,2 = −1/(2 � 11)
u8,3 = −1/(2 � 11)
u8,4 = −1/(2 � 11)
v8,1 = 1/(2 � 11)
v8,2 = 1/(2 � 11)
v8,3 = 17/(2 � 11 � 23)
v8,4 = 17/(2 � 11 � 23)
u9,1 = −1/(2 � 11)
u9,2 = −1/(2 � 11)
u9,3 = −1/(2 � 11)
u9,4 = −1/(2 � 11)
v9,1 = 1/(2 � 11)
v9,2 = 1/(2 � 11)
v9,3 = 15/(2 � 11 � 23)
v9,4 = 15/(2 � 11 � 23)
u10,1 = −1/(2 � 11)
u10,2 = −1/(2 � 11)
u10,3 = −1/(2 � 11)
u10,4 = −1/(2 � 11)
v10,1 = 1/(2 � 11)
v10,2 = 1/(2 � 11)
v10,3 = 1/(2 � 11)
v10,4 = 1/(2 � 11)
Step 1102: The sequences that meet uk,i≦(ri/Ni−k/N1)≦vk,i are selected and included into the sub-group i of the sequence group k, where the sequence is represented by a basic sequence index. Thus the following table is generated:
Example 2 If the sequence group contains more sub-groups, after u and v are calculated to a certain sub-group, u and v of the sub-groups of longer sequences do not change any more. For example, if the system bandwidth is 5 Mbps, the sequence lengths include: N1=11, N2=23, N3=37, N4=47, N5=59, N6=71, N7=97, N8=107, N9=113, N10=139, N11=179, N12=191, N13=211, N14=239, N15=283, and N16=293. Taking the fourth sequence group as an example, namely, k=4, v4,i and u5,i iε{1,2,3, . . . , 16} are obtained in the following way:
For the sub-group 1, v4,1=1/(2�11), and u5,1=−1/(2�11).
For the sub-group 3, right4,2=v4,2+4/11=1/(2�11)+4/11, and left5,2=u5,2+5/11=−1/(2�11)+5/11.
For N2=23, when r2 varies, if r5,2=10, then r5,2/N2−left5,2<0 and |r5,2/N2−left5,2| is the minimum value; because r5,2/N2−�(N2)−right4,2>0, v4,3=v4,2, namely, v4,3=1/(2�11).
For N2=23, when r2 varies, if r4,2=9, then r4,2/N2−right4,2<0 and |r4,2/N2−right4,2| is the minimum value; because r4,2/N2+1(2N2)−left5,2>0,
u 5 , 3 =  u 5 , 2 + r 4 , 2 / N 2 + 1 / ( 2   N 2 ) - left 5 , 2 =  - 1 / ( 2 � 11 ) + 9 / 23 + 1 / ( 2 � 23 ) - ( - 1 / ( 2 � 11 ) + 5 / 11 ) =  - 21 / ( 2 � 11 � 23 ) . For the sub-group 4, right4,3=v4,3+4/11=1/(2�11)+4/11, and left5,3=u5,3+5/11=−21/(2�11�23)+5/11.
u 5 , 4 =  u 5 , 3 + r 4 , 3 / N 3 + 1 / ( 2   N 3 ) - left 5 , 3 =  - 21 / ( 2 � 11 � 23 ) + 15 / 37 + 1 / ( 2 � 37 ) -  ( - 21 / ( 2 � 11 � 23 ) + 5 / 11 ) =  - 29 / ( 2 � 11 � 37 ) For the sub-group 5, v4,5=v4,4, namely, v4,5=1/(2�11); u5,5=u5,4, namely, u5,5=−29/(2�11�37).
For the sub-group 6, v4,6=v4,5, namely, v4,6=1/(2�11); u5,6=u5,5, namely, u5,6=−29/(2�11�37).
For the sub-group 7, 6v4,7=v4, namely, v4,7=1/(2�11); u5,7=u5,6, namely, u5,7=−29/(2�11�37).
Further calculation reveals that: for sub-groups 8, 9, 10, . . . , 16, the values of u and v do not change any more.
By analogy, u and v of all sub-groups of other sequence groups may be obtained. Calculation reveals that: for any sub-group i of the sequence group 5, v5,i=1/(2�11). Based on the foregoing calculation, the sequences that meet u5,i≦(ri/Ni−5/N1)≦v5,i are selected and included into the sub-group i of the sequence group 5, where the sequence is represented by a basic sequence index. Thus the following table is generated:
N1 = 11 group number k
N2 = 23 basic sequence index r2 10, 11
N3 = 37 basic sequence index r3 16, 17, 18
N4 = 47 basic sequence index r4 20, 21, 22, 23
N5 = 59 basic sequence index r5 25, 26, 27, 28, 29
N6 = 71 basic sequence index r6 30, 31, 32, 33, 34, 35
N7 = 97 basic sequence index r7 41, 42, 43, 44, 45, 46, 47, 48
N8 = 107 basic sequence index r8 45, 46, 47, 48, 49, 50, 51, 52, 53
N9 = 113 basic sequence index r9 48, 49, 50, 51, 52, 53, 54, 55, 56
N10 = 139 basic sequence index r10 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69
N11 = 179 basic sequence index r11 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86,
N12 = 191 basic sequence index r12 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92,
N13 = 211 basic sequence index r13 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100,
N14 = 239 basic sequence index r14 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
112, 113, 114, 115, 116, 117, 118, 119
N15 = 283 basic sequence index r15 119, 120, 121, 123, 124, 125, 126, 127, 128,
N16 = 293 basic sequence index r16 123, 124, 125, 126, 127, 128, 129, 130, 131,
132, 133, 134, 135, 136, 137, 138, 139, 140,
The foregoing calculation of uk,i, vk,i reveals that: the same uk,i, vk,i may be determined when calculated to N4=47 (namely, S={2,3,4}) and N16=293 (namely, S=I={2,3, . . . , 16}). Therefore, the calculation may continue only to the fourth sub-group, namely, S={2,3,4} to obtain u and v of all sub-groups of all sequence groups and reduce the calculation load.
In practice, u and v in use may be quantized according to the foregoing calculation results to achieve the required precision.
Preferably, n is 1, namely, in the foregoing example, a sequence that makes (rm/Nm−k/N1) the smallest is selected and included into the sub-group m.
Preferably, n is a natural number greater than 1, and the value of n depends on the length difference between sub-group Nm and reference sub-group N1. The sequences corresponding to several basic sequence indexes near rm th at makes (rm/Nm−k/N1) the smallest are included into a sub-group. Generally, such sequences are n sequences closest to the minimum rm, where n depends on the length difference between N1,Nm. For example, if Nm is about 4�N1, two rm's may be included into the group. Generally, n=┌Nm/(2N1)┐ may be selected. In another example, n=└Nm/N1┘ may be selected, where └z┘ is the maximum integer not greater than z. In the sequence sub-group in this case, there may be more than one sequence of a certain length. After such allocation in the system, when using the sequence, the user may select any of the allocated n sequences for transmitting, for example, select the sequence that makes (rm/Nm−k/N1) the smallest, second smallest, and so on.
In the foregoing embodiment, n sequences are selected, where n is preferably determined by the sequence group k and sub-group i. For example, n≦Q, where Q is the quantity of sequences that meet uk,i≦(ri/Ni−ck/Np1)≦vk,i, Np1 is the length of the reference sub-group sequence, and ck is the basic sequence index of the sequence with a length of NP 1 determined by the sequence group k. uk,i=−1/(2N1), vk,i=1/(2N1), or uk,i=−1/(2N1)+1/(4N2), vk,i=1/(2N1)−1/(4N2), or uk,i=−�θ, vk,i=�θ, and so on, where θ is an integer. If uk,i and vk,i are relatively small, for example, uk,i=−1/(2N1)+1/(4N2) and vk,i=1/(2N1)−1/(4N2) the correlation between any two sequences of different sequence groups is ensured to be low.
In the foregoing embodiments, the sequence groups may be generated for the sequences corresponding to partial instead of all modes of occupying time frequency resources in the system. For example, the modes of occupying time frequency resources may be divided into multiple levels according to the length of the sequence. Each level includes sequences in a certain length range. For the sequences at each level, the sequence groups are generated and allocated, as described above.
Specifically, the sequence groups may be allocated dynamically, namely, the sequence in use varies with time or other variables; or the sequence groups are allocated statically, namely, the sequence in use is constant. More specifically, the static allocation mode may be used alone, or the dynamic allocation mode is used alone, or both the dynamic allocation mode and the static allocation mode are used, as detailed below:
Preferably, if few radio resources are occupied by the sequence, the sequence groups are allocated dynamically. That is because the sequent length is small in this circumstance, and there are fewer sequence groups. For example, as regards the method of �hopping� a sequence group: in the foregoing embodiment taking the Zadoff-Chu sequence as an example, a serial number (r1) of a reference sequence group is selected randomly in the pseudo random mode at the time of transmitting the pilot frequency, and then the sequence with the index rk in the sub-group of the same sequence group is calculated out according to the foregoing selection mode.
Preferably, if many radio resources are occupied by the sequence, the sequence groups are allocated statically. For example, in the foregoing embodiment taking the Zadoff-Chu sequence as an example, if the quantity (N) of sequence groups meets the need, the N sequence groups are allocated to each cell, which meets the requirements of averaged interference between cells without changing with time. Preferably, the radio resources occupied in the system may be divided into two levels. One level is about the sequences that occupy many radio resources, where different sequence groups are allocated statically; the other level is about the sequences that occupy few radio resources, where the sequence groups allocated in the dynamic pseudo random mode. For example, if a sequence occupies more than 144 sub-carriers, the sequence length is generally greater than or equal to 144, and different sequence groups are allocated statically; if the sequences in each sequence group correspond to radio resources of less than 144 sub-carriers, the sequence length is generally less than 144, and the sequence groups are allocated in the dynamic pseudo random mode.
If a sub-group contains multiple sequences, including basic sequences and the sequences of different time cyclic shifts, the sequences may be allocated not only to different users, but also to different cells, for example, different sectors under a base station. Particularly, if a cell needs more sequences, for example, if multi-antenna transmitting is supported, each antenna needs to have a different sequence. In this case, the minimum length of the sequence in use may be limited to increase the quantity of basic sequences in the sub-group. Therefore, more basic sequences in the sub-group or more cyclic shifts of the basic sequences may be allocated to the cell. Further, if the sub-group in the sequence group has multiple sequences, the sequence groups may be further grouped and allocated to different cells, users or channels.
The aforementioned sequences are not limited to Zadoff-Chu sequences, and may be Gauss sequences, other CAZAC sequences, basic sequences, and/or deferred sequences of CAZAC sequences.
Embodiment 2 Corresponding to the aforementioned method for allocating sequence groups to cells in a specific selection mode in a network, a method for processing communication sequences is described. As shown in FIG. 4, the process of the method includes:
Step 201: The group number k of the sequence group allocated by the system is obtained.
Step 202: N (n is a natural number) sequences are selected from the candidate sequence collection to form sequences in the sub-group i (i is a serial number of the sub-group) in the sequence group k, where the n sequences make the d(�i(�), Gk) function value the smallest, second smallest, and third smallest respectively, d(a,b) is a two variables function, Gk is a variable determined by the group number k, �i(�) is a function corresponding to the sub-group i determined by the system, and the domain of the function is the candidate sequence collection corresponding to the sub-group i.
Step 203: The corresponding transmitting sequences are generated according to the formed sub-group i, and the sequences on the corresponding time frequency resources are processed.
Processing of communication sequences includes transmitting and receiving of communication sequences. Receiving of communication sequences includes calculation related to the generated sequences and received signals. Generally, the specific receiving operations include the calculation for obtaining channel estimation or time synchronization.
The aforementioned sequences are not limited to Zadoff-Chu sequences, and may be Gauss sequences, other CAZAC sequences, basic sequences, and/or shifted sequences of CAZAC sequences. The processing of sequences may be frequency domain processing or time domain processing. The functions in the foregoing method may be consistent with the functions in the foregoing allocation method, and are not repeated further.
Taking the Zadoff-Chu sequence as an example, if the function d(a,b) is d(a,b)=|(a−b)|, for the sub-group m, the sequence that makes the |rm/Nm−k/N1| value the smallest is selected and included into the sequence group k, thus ensuring higher correlation between sequences and reducing correlation between groups.
In practice, working out the rm indexes that make |rm/Nm−k/N1| the smallest, second smallest, . . . , may induce a general method. That is, with an known integer N1,N2, e, the integer � needs to make the |e/N1−�/N2| value the smallest. Evidently, � is the integer w closest to e�N2/N1, namely, the └e�N2/N1┘ value rounded down or the ┌e�N2/N1┐ value rounded up. The fewer n sequences are w�1, w�2, . . . .
The transmitter and the receiver may obtain the data through calculation in this way rather than store the data.
Still taking the Zadoff-Chu sequence as an example, if the function d(a,b) is |(a−b) modu mk,i|, the sub-group numbered p1 serves as a reference sub-group, Np 1 is the length of the reference sub-group sequence, ck is the basic sequence index of the sequence with a length of Np 1 determined by the sequence group k, Ni is the length of the sequence of the sub-group i, and ri is the basic sequence index of the sequence with a length of Ni determined by the sequence group k, then, |(a−b) modu mk,i|=|(ri/Ni−ck/Np 1 ) modu mk,i|. Particularly, Np 1 =N1 and ck=k may be selected. For the sub-group i=q in the sequence group k, the sequence that makes |(rq/Nq−k/N1) modu mk,q| the smallest is selected and included into the sequence group k. Therefore, the selected sequence is the most correlated with the sequence of the reference length in the same sequence group, the correlation of the sequences between different groups is further reduced, and the inter-group interference is weaker.
In practice, working out the index rq that makes |(rq/Nq−k/N1) modu mk,q| the smallest may induce a general method, namely, rq=B−1�round (B�k�Nq/N1), where B=1/mk,q, B−1 is a natural number that meets B�B−1 mod Nq=1, and round(z) is an integer closest to z.
A detailed description is given below through examples. With a known integer N1, N2, e, if mk,q=1, then the integer � needs to make the |(e/N1−�/N2) modu 1| value the smallest. Evidently, � is the integer w closest to e�N2/N1, namely, the └e�N2/N1┘ value rounded down or the ┌e�N2/N1┐ value rounded up. If mk,q=�, then the integer � needs to make the |(e/N1−�/N2) modu �| value the smallest. � is
w � 1 + N 2 2   modu   1   o   N 2 , namely,
w � 1 + N 2 2   mod   N 2 , where w is an integer closest to 2e�N2/N1, namely, the └2e�N2/N1┘ value rounded down or the └2e�N2/N1┘ value rounded up. If mk,q=⅓, then the integer � needs to make the |(e/N1−�/N2) modu ⅓| value the smallest. When N2 mod 3=0, � is w/3; when N2 mod 3=1, � is
w � 1 - N 2 3   mod   N 2 ; when N2 mod 3=2, � is
w � 1 + N 2 3   mod   N 2 , where w is an integer closest to 3e�N2/N1, namely, the └3e�N2/N1┘ value rounded down or the └3e�N2/N1┘ value rounded up. If mk,q=�, then the integer � needs to make the |(e/N1−�/N2) modu �| value the smallest. When N2 mod 2=0, � is w/4; when N2 mod 4=1, � is
w � 1 + N 2 4   mod   N 2 , when N2 mod 4=3, � is
w � 1 - N 2 4   mod   N 2 ; where w is an integer closest to 4e�N2/N1, namely, the └4e�N2/N1┘ value rounded down or the ┌4e�N2/N1┐ value rounded up.
To sum up, through mk,q storage and simple calculation, the sequences in the sub-group q in the sequence group k are obtained. According to the inherent features of mk,q, the mk,q storage may be simplified, as detailed below:
mk,q of the sub-group q is symmetric between different sequence groups k, namely, mk,q=mT−k,q, where T is the total number of sequence groups. Therefore, if mk,q in the case of 1≦k≦T/2 is pre-stored, mk,q in the case of 1≦k≦T can be obtained; or, if mk,q in the case of T/2<k≦T is pre-stored, mk,q in the case of 1≦k≦T can also be obtained.
If Nq≧Lr, it is appropriate that mk,q=1, where Nq is the sequence length of the sub-group q, and Lr is determined by the reference sub-group sequence length Np 1 . Specifically, for Np 1 =N1=31, Lr=139. If Nq=139 or above, then mk,q=1. After cyclic extension of the sequence, Lr=191. Therefore, when Nq=191 or above, mk,q=1.
The specific values of mk,q corresponding to the sub-group q in the sequence group k may be stored. Specifically, x bits may be used to represent W different values of mk,q, where 2x−1<W≦2x; for each mk,q, the x bits that represent the specific values of mk,q are stored. Alternatively, the value selection mode of mk,q may also be stored. For example, when Nq≧Lr, mk,q=1.
In the foregoing embodiment, after the resource occupied by the sequence is determined, the sequence of the sub-group corresponding to the resource of the current group may be generated in real time according to the selection mode, without the need of storing. The implementation is simple.
It is understandable to those skilled in the art that all or part of the steps in the foregoing embodiments may be implemented by hardware instructed by a program. The program may be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk and compact disk, and the steps covered in executing the program are consistent with the foregoing steps 201-203.
Embodiment 3 As shown in FIG. 5, an apparatus for processing communication sequences by using the foregoing communication sequence processing method includes:
a sequence selecting unit, adapted to: obtain a group number k of a sequence group allocated by the system, and select n (n is a natural number) sequences from a candidate sequence collection to form sequences in a sub-group i (i is a serial number of the sub-group) in the sequence group k (k is the serial number of the sequence group), where the n sequences make the d(�i(�), Gk) function value the smallest, second smallest, and third smallest respectively, d(a,b) is a two variables function, Gk is a variable determined by the group number k, �i(�) is a function corresponding to the sub-group i determined by the system, and the domain of the function is the candidate sequence collection corresponding to the sub-group i; and
a sequence processing unit, adapted to: select or generate the corresponding sequences according to the sequences in the formed sub-group i, and process the sequences on the time frequency resources corresponding to the sub-group i.
Specifically, as shown in FIG. 6, the sequence processing unit is a sequence transmitting unit adapted to generate the corresponding sequences according to the formed sequences and transmit the sequences on the corresponding time frequency resources. In this case, the communication sequence processing apparatus is a communication sequence transmitting apparatus.
Specifically, as shown in FIG. 7, the sequence processing unit may be a sequence receiving unit adapted to generate the corresponding sequences according to the formed sequences and receive the sequences on the corresponding time frequency resources. In this case, the communication sequence processing apparatus is a communication sequence receiving apparatus. The receiving processing generally includes calculation related to the generated sequences and received signals. Generally, the specific receiving operations include the calculation for obtaining channel estimation or time synchronization.
The relevant functions and specific processing in the communication sequence processing apparatus are consistent with those in the forgoing allocation method and processing method, and are not repeated further. The aforementioned sequences are not limited to Zadoff-Chu sequences, and may be Gauss sequences, other CAZAC sequences, basic sequences, and/or deferred sequences of CAZAC sequences. The processing of sequences may be frequency domain processing or time domain processing.
In the foregoing communication sequence processing apparatus, the sequence selecting unit selects a sequence compliant with the interference requirement directly in a specific selection mode, without the need of storing the lists about the correspondence of sequences, thus saving communication resources as against the conventional art.
Although exemplary embodiments have been described through the application and accompanying drawings, the claims are not limited to such embodiments. It is apparent that those skilled in the art can make various modifications and variations to the embodiments without departing from the spirit and scope of the claims.
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