WO2008020624A1

WO2008020624A1 - Code sequence allocation method

Info

Publication number: WO2008020624A1
Application number: PCT/JP2007/066019
Authority: WO
Inventors: Tomofumi Takata; Takashi Iwai; Daichi Imamura; Sadaki Futagi
Original assignee: Panasonic Corporation
Priority date: 2006-08-18
Filing date: 2007-08-17
Publication date: 2008-02-21

Abstract

Disclosed is a code sequence allocation method capable of suppressing inter-cell interference and reducing in-cell interference when allocating a ZCZ-GCL code sequence for each cell. In this method, if a code sequence of sequence numbers r2, r3, &mldr;, r7 have been allocated for cells #2 to #7, a code sequence having a sequence number r1 which is relatively prime to r2, r3, &mldr;, r7 and wherein the total of the greatest common measures between a difference from each of r2, r3, &mldr;, r7 and the sequence length N is minimum is allocated for the cell #1 adjacent to the cells #2 to #7.

Description

Specification

Code sequence allocation method

Technical field

[0001] The present invention relates to a code sequence allocation method used in a cellular radio communication system.

Background art

[0002] Currently, in 3GPP RAN LTE (Long Term Evolution), code sequences used as a random access preamble signal, downlink synchronization signal, and uplink / downlink channel estimation pilot signal in a cellular radio communication system are actively discussed. ing. In cellular radio communication systems, good self-code sequences are used to reduce interference between different mobile stations in a cell (intra-cell interference) and between mobile stations between different cells (inter-cell interference). Correlation characteristics and cross-correlation characteristics are required. ZC (Zadoff-Chu) sequences and GCL (Generalized Chirp-Like) sequences are good candidates for code systems that satisfy these requirements.

[0003] Among them, a ZCZ (Zero Correlation Zone) —GCL system IJ, which is a subset of the GCL sequence and expressed by the following equation (1), is expressed as s [Fixed m, FFT (Fast Fourier Transform; Since the correlation calculation can be performed by the block configuration and the calculation amount of the reception processing can be reduced, it is a particularly strong candidate as a code sequence used in the cellular radio communication system.

Country c _r (n) = _r (k) b _t (k mod m), ()

= 0, 1, ..., N - in 1 set (1), N denotes the sequence ^{length, N = s X m 2 (} s, m are integers), or N = t X m (t, m is (Integer) and consists of a non-prime integer. r indicates the sequence number, and consists of an integer that is relatively prime to N. a (k) represents a carrier sequence and is a ZC sequence power expressed by the following equation (2).

In the formula (2), q is an arbitrary integer. Also, in equation (1), b. (K) represents the modulation sequence and is represented by the following DFT (Discrete Fourier Transform) system lj represented by equation (3) below or equation (4) below. It consists of the Hadamard series.

[Equation 3] b. (K) = Wl „ ^k ,

k = 0, \, ..., N-I (3)

i = 0 ₇ l, ..., m-\

0,1, .. N-1 (4)

i = 0 丄…, —1

[0004] In general, for a ZC sequence whose sequence length is a prime integer, the difference between any two sequence numbers and the sequence length are always prime, and the amplitude value of the cross-correlation between the two sequences is ^ N, so intra-cell interference or inter-cell interference is suppressed to a certain level.

[0005] Since the sequence length of the ZCZ-GCL sequence shown in Equation (1) above is not a prime number,

The difference between the two sequence numbers and the sequence length are not always prime. Therefore, the maximum amplitude value of the cross-correlation between any two sequences (maximum cross-correlation value) may become larger, increasing intra-cell interference and inter-cell interference. In order to avoid such problems, ZCZ-GCL sequence allocation methods disclosed in Non-Patent Document 1 are being studied in cellular radio communication systems.

[0006] Non-Patent Document 1 discloses a method for assigning a ZCZ-GCL sequence used as a random access preamble signal.

FIG. 1 is a diagram illustrating an example of allocation of ZCZ-GCL sequences disclosed in Non-Patent Document 1. . In this figure, the case where the sequence length N is N = 448 is taken as an example. If N = 448, the system ある IJ number r that is prime with N is r = l, 3, 5, 9, 11, 13, 15, 17, ..., 447, and ZCZ for the number of r — A GCL series is generated. As shown in Fig. 1, among the ZCZ-GCL sequences for the number r, ZCZ-GCL sequences with closer sequence numbers are allocated to the same cell (Cell). In other words, ZCZ—GCL series IJs with series IJ numbers 1, 3, 5, 9,..., 31 are assigned to Senole # 1 to # 7, two at a time.

[0008] Thus, in the ZCZ-GCL sequence allocation method disclosed in Non-Patent Document 1, based on the characteristics of the ZCZ-GCL sequence that the cross-correlation of the ZCZ-GCL sequence is smaller as the sequence number is closer, Sequences with similar sequence numbers are placed in the same cell.

Non-Patent Document 1: 3GPP, R1- 0661816, Huawei, "Expanded sets of ZCZ- GCL random access preambles

Disclosure of the invention

Problems to be solved by the invention

[0009] However, since the ZCZ—GCL sequence allocation method disclosed in Non-Patent Document 1 described above considers only intra-cell interference and not inter-cell interference, it suppresses inter-cell interference. I can't. For example, in Figure 1, the maximum cross-correlation between the Z CZ—GCL sequence with sequence number 1 assigned to cell # 1 and the ZCZ—GCL sequence with sequence number 29 assigned to cell # 7 is ^ (28 XN), more than 5 times.

[0010] Further, even if two ZCZ-GCL sequences having similar sequence numbers are assigned to the same cell, the maximum cross-correlation value is not always small, and therefore ZCZ disclosed in Non-Patent Document 1 — The GCL sequence allocation method cannot minimize intra-cell interference. For example, as shown in Fig. 1, when assigning sequence # 19 to cell # 5 and sequence 系 IJ of sequence number 23, the maximum cross-correlation value of these two sequences is (4 XN). When the sequence number 19 and the sequence number 45 are assigned to # 5, the difference between the sequence numbers of the two sequences increases, but the maximum cross-correlation value becomes smaller, and f (2 XN).

An object of the present invention is to provide a code sequence allocation method that can suppress inter-cell interference and reduce intra-cell interference. Means for solving the problem

[0012] The code sequence allocating method of the present invention is a code sequence in which ZCZ—GCL code sequence C ^ k) shown in the above equation (1) is allocated to! / Of a plurality of cells constituting a cellular radio communication system. In the allocation method, among the code sequences C (k) generated by the above equation (1), r of each of the code sequences already allocated to a plurality of second cells adjacent to the first cell is relatively prime. And a first code sequence having r that minimizes the sum of the greatest common divisors of N and the difference between each of the code sequences already allocated to the plurality of second cells. I made it.

The invention's effect

[0013] According to the present invention, it is possible to suppress inter-cell interference and reduce the intra-cell interference with a force S.

Brief Description of Drawings

[0014] FIG. 1 is a diagram showing an example of ZCZ-GCL sequence allocation according to the prior art.

FIG. 2 is a diagram showing the relationship between the greatest common divisor between the sequence number difference and the sequence length of the code sequence and the maximum cross-correlation value of the code sequence according to the present invention.

[Fig.3] Number of simulation results shown in Fig. 1

FIG. 4 is a diagram for explaining a code sequence allocation method for the cellular radio communication system according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a procedure of a code sequence allocation method for a cellular radio communication system according to Embodiment 1 of the present invention.

FIG. 6 is a diagram showing an example of a result of code sequence allocation using the code sequence allocation method according to Embodiment 1 of the present invention.

FIG. 7 is a diagram for explaining a code sequence allocation method for a cellular radio communication system according to a second embodiment of the present invention.

FIG. 8 is a flowchart showing a procedure of a code sequence allocation method for a cellular radio communication system according to Embodiment 2 of the present invention.

FIG. 9 is a diagram showing an example of a result of code sequence allocation using the code sequence allocation method according to Embodiment 2 of the present invention. FIG. 10 is a diagram for explaining a code sequence allocation method of a cellular radio communication system according to a third embodiment of the present invention.

FIG. 11 is a flowchart showing a procedure of a code sequence allocation method for a cellular radio communication system according to Embodiment 3 of the present invention.

FIG. 12 is a diagram for explaining a code sequence allocation method for a cellular radio communication system according to a fourth embodiment of the present invention.

FIG. 13 is a flowchart showing a procedure of a code sequence allocation method for a cellular radio communication system according to Embodiment 4 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] The code sequence allocation method according to the present invention includes a greatest common divisor between a sequence number difference and a sequence length of a ZCZ-GCL sequence whose sequence length is not a prime number, which has been solved by the computer simulation of the present inventors. ZCZ—Based on the relationship with the GCL sequence maximum cross-correlation value. First, the relationship between the greatest common divisor and the largest cross-correlation value will be explained. In the following description, the ZC Z—GCL sequence is abbreviated as a code sequence.

FIG. 2 is a diagram showing the relationship between the greatest common divisor between the sequence number difference of the code sequence and the sequence length, and the maximum cross-correlation value of the code sequence. This figure is a result obtained by the present inventors performing a computer simulation. Fig. 2A shows the greatest common divisor between sequence number differences and sequence lengths. In FIG. 2A, the horizontal axis indicates the difference between the sequence numbers of the code sequences, and the vertical axis indicates the greatest common divisor between the difference between the sequence numbers and the sequence length. FIG. 2B is a diagram showing the maximum cross-correlation value of the code sequence corresponding to the difference in the sequence number of the code sequence. In FIG. 2B, the horizontal axis indicates the difference between the sequence numbers of the code sequences, and the vertical axis indicates the maximum cross-correlation value of the code sequences corresponding to this difference. As shown in Fig. 2, the change in the greatest common divisor corresponding to the difference in the sequence numbers of the code sequences is almost the same as the change in the maximum cross-correlation value.

FIG. 3 shows the simulation results shown in FIG. 2 in numerical values. In FIG. 3, the first column and the second column indicate the sequence numbers r and r of the two code sequences, respectively. here

1 2

And r and r are relatively prime. The third column shows the difference between these two sequence numbers | r−r |

1 2 1 2 and the fourth column shows the maximum cross-correlation value of the two code sequences. The fifth column shows the greatest common divisor between the sequence number difference and the sequence length, that is, GCD (I r -r |, Ν), and the sixth column is ^ (system Greatest common divisor between column number difference and sequence length) (sequence length), ie (GCD (I r -r

1 2

I, N)) Indicates the value of X ^ N. As shown in this figure, when the sequence numbers of the code sequences are relatively prime, the greatest common divisor between the sequence number difference and the sequence length is equal to the maximum cross-correlation value. ) Is obtained.

Maximum cross-correlation value = ^ (greatest common divisor between sequence number difference and sequence length) (sequence length) · '· (5

)

Accordingly, in the present invention, the code sequence is transmitted to the cellular radio communication so that the greatest common divisor between the sequence number difference and the sequence length of the code sequence is minimized using the relationship shown in Equation (5). Assign to each cell in the system to reduce the maximum cross-correlation value between code sequences. As a result, inter-cell interference can be suppressed and intra-cell interference can also be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0020] (Embodiment 1)

FIG. 4 is a diagram for explaining a code sequence allocation method of the cellular radio communication system according to the present embodiment. Here, an example of a cellular radio communication system using cells # 1 to # 19 is shown.

In the present embodiment, as shown in FIG. 4, code sequences of sequence numbers r to r are already assigned to the codes # 2 to # 7 adjacent to the code # 1 (hereinafter referred to as code sequences r to r). Is assigned

2 7 2 7

Based on the code sequences assigned to the cells # 2 to # 7, a method for assigning the code sequence r to the cell # 1 will be described.

FIG. 5 is a flowchart showing the procedure of the code sequence assignment method for the cellular radio communication system according to the present embodiment.

First, in step (hereinafter referred to as “ST”) 101, variables Sum, r, and r are initialized to “0”, and variable Min is initialized to N X K = N X 6. Here, N indicates the sequence length, and K indicates the number of cells adjacent to Senole # 1. In the present embodiment, the variable Min is the difference between the sequence number of the code sequence assigned to cell # 1 and each of the sequence numbers r 1, r 2,.

2 3 7

This variable stores the minimum sum of common divisors. Since the greatest common divisor between the difference between any two sequence numbers and the sequence length N is always smaller than N, for example, when the sequence length N is 448, the variable Min is initialized to 448 X 6 = 2688. [0024] Next, in ST102, code systems 歹 IJr to r already assigned to cells # 2 to # 7

A set of code sequences having a sequence number that is relatively prime to 2 7 is set as a candidate set of code sequences to be assigned to cell # 1, and any one of the candidate sets that has not yet been selected is selected. . In this step, a variable is set using the sequence number of the selected candidate code sequence.

[0025] Next, in ST103, the difference between the variable r and the sequence number r (i = 2, 3, ···, 7) and the sequence length

Calculate the sum of the greatest common divisor with N and assign the result to the variable Sum. That is, the calculation shown in the following formula (6) is performed.

[Number 5

Sum = GCD (\ r _x - _ri \, N)… ( ₆ )

Next, in ST104, the value of variable Sum is compared with the value of variable Min. In this step, if it is determined that the value of the variable Sum is greater than or equal to the value of the variable Min (ST104: NO), the allocation procedure proceeds to ST106. On the other hand, when it is determined in ST104 that the value of variable Sum is smaller than the value of variable Min (ST104: YES), the allocation procedure proceeds to ST105.

[0027] Next, in ST105, the variable Min is updated using the value of the variable Sum, and the variable r is updated using the value of the variable r.

[0028] Next, in ST106, it is determined whether all candidate code sequences to be assigned to cell # 1 have been selected. If it is determined in this step that all candidate code sequences have not been selected (ST106: NO), the allocation procedure returns to ST102. On the other hand, if it is determined that all candidate code sequences have been selected (ST106: YES), a code sequence having the value of variable r as the sequence number is assigned to cell # 1.

[0029] As described above, in the assignment procedure shown in FIG. 5, the sequence numbers r 1, r 2,..., R of code sequences already assigned to cells # 2 to # 7 are relatively prime. , Series number r, r,

2 3 7 2 3

, r By assigning to cell # 1 a code sequence having sequence number r that minimizes the sum of the greatest common divisors of the differences between each and sequence length N, inter-cell interference is suppressed.

FIG. 6 shows the result of code sequence allocation performed using the code sequence allocation method according to the present embodiment. It is a figure which shows an example of a fruit.

[0031] Fig. 6 As shown, ί and senore # 2 to # 7 are each assigned a code sequence with sequence numbers 443, 179, 163, 295, 215 and 67, respectively. If r is calculated according to the procedure shown in the flowchart of Fig. 5, the result of r = 69 is obtained. That is, if the code sequence with sequence number 69 is assigned to cell # 1, inter-cell interference is minimized.

[0032] Thus, according to the present embodiment, the sequence numbers of code sequences already assigned to a plurality of cells are relatively prime to each other, and each of the code sequences already assigned to the plurality of cells. A code sequence having a sequence number that minimizes the sum of the greatest common divisors of the difference from the sequence number and the sequence length is assigned to one cell adjacent to all of the cells. For this reason, according to the present embodiment, it is possible to suppress inter-cell interference.

In the present embodiment, the method of calculating the greatest common divisor between the sequence number difference of the code sequences and the sequence length and allocating the code sequence based on the calculated greatest common divisor has been described. The maximum cross-correlation value between code sequences shown in Equation (5) may be calculated, and the code sequence may be assigned based on the calculated maximum cross-correlation value. As shown in Equation (5), the lower the greatest common divisor between the sequence number difference and the sequence length, the lower the maximum cross-correlation value. The greatest common divisor between the difference and the sequence length is equivalent to the largest cross-correlation value. Therefore, the sum of the maximum cross-correlation values with the sequence numbers that are relatively prime to the sequence numbers of the code sequences already assigned to the plurality of cells and the code sequences already assigned to the plurality of cells. By assigning the code sequence that minimizes to one cell adjacent to all of the plurality of cells, inter-cell interference can be suppressed as in the present embodiment.

[0034] Further, in the present embodiment, the code sequence assigned to the cellular radio communication system is not limited to the force S, ZCZ- GCL system IJ described as an example of the ZC Z-GCL sequence, and the sequence length is not a prime number. Even when the ZC sequence is assigned to the cellular radio communication system, the code sequence assignment method according to the present embodiment may be applied. In such a case, the same effect as in the present embodiment can be obtained.

In this embodiment, the force variable Min is initialized to a value larger than NXK = NX 6 described in ST101 as an example when the variable Min is initialized to NXK = NX 6 in ST101. May be.

[0036] (Embodiment 2)

FIG. 7 is a diagram for explaining a code sequence allocation method of the cellular radio communication system according to Embodiment 2 of the present invention. Here, an example of a cellular wireless communication system using cells # 1 to 19 is shown.

In the present embodiment, as shown in FIG. 7, two code sequences r to r are already assigned in order to each cell of senor # 2 to # 7 adjacent to senor # 1. These cells

3 14

Based on the code sequences assigned to # 2 to # 7, two code sequences r and r are assigned to cell # 1.

1 2

Explain how to do this.

FIG. 8 is a flowchart showing the procedure of the code sequence assignment method for the cellular radio communication system according to the present embodiment.

[0039] First, ST20: This time, variables r, r, Gcdl, Gcd2, Suml, Sum2, r, r are set to "0".

xl x2 1 2 and the variable Min is initialized to NX (KXL) XL + NX (LX (L— 1) / 2!) = NX6X2X 2 + N. Here, N indicates the sequence length, K indicates the number of cells adjacent to cell # 1, and L indicates the number of code sequences assigned to each cell. K XL indicates the number of all code sequences assigned to the cell adjacent to cell # 1, LX (L— 1) / 2! Indicates two combinations of code sequences assigned to each cell. In the present embodiment, the variable Min is a sequence number of each of the two code sequences assigned to cell # 1, and each of the sequence numbers r 1, r 2,.

3 4 Save the minimum value of the sum of the greatest common divisor between the difference of 14 and the sequence length N and the difference between the sequence numbers of the two code sequences assigned to cell 1 and the greatest common divisor of the sequence length N It is a variable to do.

[0040] Next, in ST202, code sequences r to r already assigned to cells # 2 to # 7

3 Assign a set of code sequences with sequence numbers that are relatively prime to 1 to cell # 1

Four

Select any two of the candidate sets that have not yet been selected. In this step, variables r and r are set using the sequence numbers of the two selected candidate code sequences.

xl x2

[0041] Next, in ST203, according to the following equation (7), the difference between the variables r and r and the sequence length N

xl x2

The greatest common divisor Gcdl is calculated, and according to the following equation (8), each of the variables r and r and r 1, r 2,. Calculate the minimum value Gcd2 of the greatest common divisor between the difference between each and the sequence length N.

Gcdl = GCD (| r -r |, Ν)… (7)

xl x2

Gcd2 = min (GCD (| r -r |, N), GCD (| r -r |, N))

xl i x2 i

Where i = 3, 4, ··· 14 '· (8)

Further, in this step, the calculated Gcdl and Gcd2 are compared to determine whether or not it is GcdKGc d2. If Gcdl≥Gcd2 is determined (ST203: NO), the allocation procedure returns to ST202. On the other hand, if it is determined that Gcdl <Gcd2 (ST203: YES), the allocation procedure proceeds to ST204.

[0042] Next, in ST204, according to the following equation (9), variables r and r and sequence numbers r to r

xl x2 3 14 Calculate the sum Suml of the greatest common divisors of the difference between each and the sequence length N.

[Equation 6]

Suml = ¾ (GCD (\ r _xl -η |, Ν) + GCD {\ r _x2 -η |), Ν)… ( ₉ )

[0043] Next, in ST205, according to the following equation (10), the difference between the variables r and r and the sequence length N

xl x2

And calculate the greatest common divisor Sum2. Here, Sum2 is equal to Gc dl calculated in ST203.

Sum2 = GCD (| r -r |, N) --- (10)

xl x2

[0044] Next, in ST206, it is determined whether or not the sum of the variable Suml and the variable Sum2 is smaller than the value of the variable Min. If it is determined that the sum of the variable Suml and the variable Sum2, that is, (Suml + Sum2) is greater than or equal to the value of the variable Min (ST206: NO), the allocation procedure proceeds to ST208. On the other hand, if the variable Suml and the variable Sum2 are determined from the value of the local variable Min, / J ヽ and half IJ (ST206: YES), the allocation procedure proceeds to ST207.

Next, in ST207, the variable Min is updated using (Suml + Sum2), and the variable r

xl

Update the variables r and r with the values of r and r.

x2 1 2

[0046] Next, in ST208, it is determined whether all candidate code sequences to be assigned to cell # 1 have been selected. If it is determined in this step that all candidate code sequences have not been selected (ST208: NO), the allocation procedure returns to ST202. On the other hand If it is determined that all candidate code sequences have been selected (ST208: YES), the values of variables r and r

1 2 Assign two code sequences, each with a sequence number, to cell # 1.

[0047] As described above, in the assignment procedure shown in FIG. 8, when two code sequences r 1, r 2,. Sequence number r, r,…

3 4 14 3 4

, r are relatively prime, and the greatest common between the difference between each of the sequence numbers r 1, r 2,.

14 3 4 14

R, r, where the greatest common divisor of the difference between each other and the sequence length N is smaller than the divisor, and

1 2

, Sequence number r, r, · ·, r The sequence number is the sum of the greatest common divisors of the difference between each and the sequence length N

3 4 14

R and r are the sequence numbers that minimize the result of adding the greatest common divisor of the difference between them and the sequence length N.

1 2

Assign two code sequences to cell # 1. As a result, both intra-cell interference and inter-cell interference can be suppressed.

[0048] FIG. 9 is a diagram showing an example of a result of code sequence allocation using the code sequence allocation method according to the present embodiment.

[0049] As shown in FIG. 9, the cell numbers # 2 to # 7 adjacent to cell # 1 are already assigned to the series number S, respectively 439, 309, 359, 197, 127, 121, 85, 303, When two code sequences of 247, 313, 19, 53 are assigned in order, r and r are calculated according to the procedure shown in the flow chart of Fig. 8, and r = 349 and r = 283 are obtained. Is obtained. Series number is it

1 2 1 2

If two code sequences of 349 and 283 are assigned to cell # 1, intra-cell interference and inter-cell interference are minimized.

[0050] In the present embodiment, the case where two code sequences are assigned to each cell has been described as an example. However, based on this, a code sequence assignment method in the case where three or more code sequences are assigned to each cell is described. An analogy can be made.

Thus, according to the present embodiment, when a plurality of code sequences are already assigned to each of a plurality of cells, each of the sequence numbers of all the code sequences assigned to the plurality of cells A plurality of prime numbers that are relatively prime and have the greatest common divisor of the difference between them and the sequence length smaller than the greatest common divisor of the difference between each of the sequence numbers of all the code sequences and the sequence length. The greatest common divisor of the difference between the sequence numbers and the sequence length is added to the sum of the greatest common divisors of the sequence numbers and the difference between each of the sequence numbers of all the code sequences and the sequence length. A plurality of code sequences each having a plurality of sequence numbers with the smallest result, To one cell adjacent to multiple cells. For this reason, according to this embodiment,

Both in-cell interference and inter-cell interference can be suppressed.

In the present embodiment, the method of calculating the greatest common divisor between the sequence number difference of the code sequences and the sequence length and allocating the code sequence based on the calculated greatest common divisor has been described. The maximum cross-correlation value between code sequences shown in Equation (5) may be calculated, and the code sequence may be assigned based on the calculated maximum cross-correlation value. That is, each of the sequence numbers of code sequences assigned to a plurality of cells has a sequence number that is relatively prime, and the mutual value is greater than the maximum cross-correlation value between all of the code sequences assigned to the cells. The maximum cross-correlation value is smaller than the sum of the maximum cross-correlation values of each of the above-described code sequences, and the maximum cross-correlation value is the smallest. By assigning a plurality of code sequences to one cell adjacent to the plurality of cells, both intra-cell interference and inter-cell interference can be suppressed as in the present embodiment.

[0053] Also, in this embodiment, there is a method for simultaneously determining r and r to be assigned to cell # 1.

1 2

However, using the code sequence allocation method shown in 1 in the embodiment, first, one code system 歹 IJr is allocated to cell # 1, and then r 1, r 2, r assigned to harmful IJ , ..., based on r

1 1 3 4 14, another code sequence r may be assigned to cell # 1. R, r, r, r, r

2 3 4 14 are relatively prime to each other, and are larger than the greatest common divisor of the difference between r 1, r 2,.

3 4 14

R is the greatest common divisor of the difference between each other and the sequence length N, and the sequence number r

twenty three

, R,…, r The sum of the greatest common divisors of the difference from each and the sequence length N is the difference between r and the sequence length N

4 14 1

The result of adding the greatest common divisor is the smallest.

2

assign.

[0054] In the present embodiment, a method of assigning two code sequences to one cell has been described. However, in a simple example, code sequences r and r are assigned to cells # 1 and # 2, respectively.

1 2, r and r are relatively prime to each other, and the difference between r and r is

1 2 1 2

A code sequence with the sequence number r as the sum of the greatest common divisor with the sequence length N

Three

# 1 or # 2 is assigned to the smaller of the difference between r and r and the greatest common divisor of sequence length N

1 2

It would be nice. Further, in the present embodiment, the case where the variable Min is initialized to ST NX (KXL) XL + NX (LX (LD / 2!) = NX6X2X2 + N in ST201 is described as an example. NX (KXL) XL + NX (LX (L— 1) / 2!) = NX 6 X 2 X 2 + You may initialize it to a value larger than N.

[Embodiment 3]

FIG. 10 is a diagram for explaining a code sequence allocation method of the cellular radio communication system according to Embodiment 3 of the present invention. Here, an example of a cellular wireless communication system using cells # 1 to 19 is shown. Each cell according to the present embodiment is divided into a central area and a peripheral area. The central area refers to the area near the base station in the cell, and the peripheral area refers to the area near the boundary line with the adjacent cell in the cell.

In the present embodiment, as shown in FIG. 10, code sequences r to r are already assigned in order to the central area and the peripheral area of each cell of senoele # 2 to # 7 adjacent to senore # 1. This

3 14

Based on the code sequences assigned to cells # 2 to # 7, a method for assigning two code sequences r and r to the center area and peripheral area of cell # 1 is explained.

1 2

Light up.

[0058] FIG. 11 is a flowchart showing a procedure of the code sequence assignment method of the cellular radio communication system according to the present embodiment.

[0059] First, in ST301, variables r, r, Suml, Sum2, r2, r are initialized to "0" and changed.

xl x2 1 2

The number Mini is initialized to NXK = NX6, and Min2 is initialized to N. Here, N indicates the sequence length, and K indicates the number of cells adjacent to cell # 1. In the present embodiment, the Mini uses the sequence number of the code sequence assigned to the peripheral area of cell # 1 and the sequence number r 1, _{r 2} , _{r 2} _,.

4 6 8 14 A variable that stores the difference between each and the minimum value of the sum of the greatest common divisors with the sequence length N. Min2 is the sequence number of the code sequence assigned to the area surrounding cell # 1 and cell # This variable stores the difference between the sequence number of the code sequence assigned to the central area of 1 and the minimum value of the greatest common divisor with the sequence length N.

[0060] Next, in ST302, code sequences r to r already assigned to cells # 2 to # 7

3 A code that assigns a set of code sequences that are relatively prime to 1 to the surrounding area of cell # 1

Four

A candidate set of series, and any one of the candidate sets that has not yet been selected select. In this step, a variable is set using the sequence number of the selected candidate code sequence.

x2

[0061] Next, in ST303, according to the following equation (1 1), variable r and cells # 2 to # 7

x2

The sequence numbers r, r, r, r, r, r for each code sequence assigned to the peripheral area of the cell

4 6 8 14 Calculate the sum of the greatest common divisor with the difference between this and the sequence length N, and substitute the calculation result into the variable Suml.

[Equation 7]

Suml = V GCD r _x2 -r _2i \, N)… (1 1)

[0062] Next, in ST304, the value of variable Suml is compared with the value of variable Mini. If it is determined in this step that Suml is greater than or equal to Mini (ST304: NO), the allocation procedure proceeds to ST306. On the other hand, when it is determined that Suml is smaller than Mini (ST304: YES), the allocation procedure proceeds to ST305.

[0063] Next, in ST305, the variable Mini is updated using the value of the variable Suml, and the variable r

Update the variable r with the value of x2.

2

[0064] Next, in ST306, it is determined whether or not all candidate code sequences to be allocated to the peripheral area of cell # 1 have been selected. If it is determined in this step that all candidate code sequences have not been selected (ST306: NO), the allocation procedure returns to ST302. On the other hand, if it is determined that all candidate code sequences have been selected (ST306: YES), the code sequence with sequence number r is assigned to the peripheral area of cell # 1, and the process proceeds to ST307.

2

Next, in ST307, code sequences r to r already assigned to cells # 2 to # 7

3 Set a set of code sequences with sequence numbers that are relatively prime to 1 and r to the center of cell # 1.

4 2

A candidate set of code sequences r to be assigned to the rear is selected, and any one of the candidate sets that has not yet been selected in this step is selected. In this step, a variable is set using the sequence number of the selected candidate code sequence.

xl

[0066] Next, in ST308, the greatest common divisor Sum2 = the difference between the variables r and r and the sequence length N

xl 2

GCD (I r -r |, N) is calculated.

2 xl

[0067] Next, in ST309, Sum2 and Min2 are compared. In this step, Su If it is determined that m2 is greater than or equal to Min2 (ST309: NO), the allocation procedure proceeds to ST311. On the other hand, when it is determined that Sum2 is smaller than Min2 (ST309: YES), the allocation procedure proceeds to ST310.

[0068] Next, in ST310, variable Min2 is updated using the value of variable Sum2, and variable r is updated using the value of variable rxl.

[0069] Next, in ST311, it is determined whether or not all candidate code sequences to be allocated to the center area of cell # 1 have been selected. If it is determined in this step that all candidate code sequences have not been selected (ST311: NO), the allocation procedure returns to ST307. On the other hand, if it is determined that all candidate code sequences have been selected (ST311: YES), the code sequence with sequence number r is assigned to the central area of cell # 1.

[0070] As described above, in the allocation procedure shown in FIG. 11, the sequence numbers r 1, r 2,. Maximum difference and sequence length

4 6 14

Assign a code sequence with r as the sequence number that has the smallest common divisor to the area surrounding cell # 1

2

In addition, a code sequence having a sequence number r that minimizes the greatest common divisor between the difference from r and the sequence length is assigned to the central area of cell # 1. As a result, both inter-cell interference and intra-cell interference can be suppressed.

As described above, according to the present embodiment, the sequence numbers of the code sequences already assigned to the peripheral areas of the plurality of cells are relatively prime to each other and are already in the peripheral areas of the plurality of cells. A code sequence having a sequence number that minimizes the sum of the greatest common divisors of the difference between the sequence number of the assigned code sequence and the sequence length is assigned to the peripheral area of one cell adjacent to the plurality of cells, Further, a code sequence having a sequence number that minimizes the greatest common divisor between the sequence number of the code sequence assigned to the peripheral area of the one cell and the sequence length is assigned to the central area of the one cell. For this reason, according to the present embodiment, it is possible to suppress both inter-cell interference and intra-cell interference.

[0072] Also, according to the present embodiment, code sequences have already been assigned to the peripheral area and the central area of a plurality of cells, and the peripheral area and the central area of one cell adjacent to the plurality of cells. When a code sequence is assigned to each cell, only the code sequence assigned to the peripheral area of those cells is considered, and the code system is assigned to the peripheral area of that one cell. After assigning a column, a code sequence is assigned to the central area of that cell, considering only the code sequence assigned to the surrounding area of that cell. For this reason, according to the present embodiment, it is possible to reduce the amount of calculation in the allocation procedure.

In the present embodiment, the method of calculating the greatest common divisor between the sequence number difference of the code sequences and the sequence length and allocating the code sequence based on the calculated greatest common divisor has been described. The maximum cross-correlation value between code sequences shown in Equation (5) may be calculated, and the code sequence may be assigned based on the calculated maximum cross-correlation value. In other words, the maximum cross-correlation value with the code sequence that has a sequence number that is relatively prime to the sequence number of the code sequence already assigned to the peripheral area of the plurality of cells. A code sequence that minimizes the sum of is assigned to the peripheral area of one cell adjacent to these cells, and the sequence number that is relatively prime to the sequence number of the code series assigned to the peripheral area of that one cell This code can also be implemented by assigning a code sequence that has a number and has the smallest maximum cross-correlation value with the code sequence assigned to the surrounding area of that cell to the center area of that cell. As in the above configuration, both inter-cell interference and intra-cell interference can be suppressed.

[0074] Also, in the present embodiment, the power explaining the method of allocating code sequences to the center area and the peripheral area of each cell will be described. To give a simpler example, code sequences have already been allocated to the cell peripheral area. Code sequence having a sequence number that is relatively prime to the sequence number of the code sequence assigned to the peripheral area of the cell and has the smallest common divisor between the difference from this sequence number and the sequence length. Is assigned to the central area of this cell.

In addition, the code sequence assignment method according to the present embodiment may be applied as a method of assigning a code sequence based on a parameter indicating propagation loss (eg, CQI (Channel Quality Information)). In this case, the code sequence allocation method for the surrounding area is applied as the code sequence allocation method when the propagation loss is large, and the code sequence allocation method for the center area is used as the code sequence allocation method when the propagation loss is small. Apply

In the present embodiment, the force variable Min is initialized to a value larger than NXK = NX 6 described in the example in ST301 where the variable Min is initialized to NXK = NX 6. May be.

[0077] (Embodiment 4)

FIG. 12 is a diagram for explaining a code sequence assignment method of the cellular radio communication system according to the fourth embodiment of the present invention. Here, an example of a cellular wireless communication system using cells # 1 to 19 is shown.

In the present embodiment, if a code sequence is still assigned to any of cells # 1 to # 7 shown in FIG. 12! /, N! /, Each cell of cells # 1 to # 7 A method for assigning a code sequence to is described.

FIG. 13 is a flowchart showing the procedure of the code sequence assignment method for the cellular radio communication system according to the present embodiment.

[0080] First, in ST401, the variables Sum, r, r, ..., r, r, r, ..., r are initialized to "0".

xl x2 x7 1 2 7

And set the variable Min to NX (K + l) XK / 2! = ΝΧ 7X6 / 2! Initialize to. Where Ν indicates the sequence length, Κ indicates the number of cells adjacent to cell # 1, and (K + l) ΧΚ / 2! Indicates two combinations of Κ + 1 code sequence. In the present embodiment, the variable Min is a variable that stores the minimum value of the sum of the greatest common divisors of the difference between the sequence numbers of the code sequences assigned to the cells # 1 to # 7 and the sequence length N.

[0081] Next, in ST402, among all combinations of seven code sequences, a set of combinations consisting of combinations whose sequence numbers are relatively prime is set as a candidate set, and the candidate set is selected from the candidate set. Choose any one combination that never happens. In this step, variables, r,..., R are set using the sequence numbers of the seven code sequences included in the selected combination.

xl x2 x7

[0082] Next, in ST403, according to the following equation (12), the variables r, r, ..., r

xl x2 x7

Then, the sum of the greatest common divisor with the sequence length is calculated, and the calculation result is substituted into the variable Sum.

[Equation 8]

Sum = J GCD {\ η1 |, N) (i ₂ ) Next, in ST404, the value of the variable Sum is compared with the value of the variable Min. If Sum is greater than or equal to Min (ST404: NO), the allocation procedure proceeds to ST406, while Sum force SMi If it is smaller than n (ST404: YES), the allocation procedure proceeds to ST405.

Next, in ST405, the value of variable Min is updated using the value of variable Sum, and variable r

, r,..., r is used to update r, r,.

1 x2 x7 1 2 7

Next, in ST406, it is determined whether or not all combinations included in the candidate set have been selected. If it is determined that all combinations included in the candidate set are not selected (ST406: NO), the assignment procedure returns to ST402, and all combinations included in the candidate set are selected. When judged (ST406: YES), variables, r, ...,

1 2 r A code sequence having a sequence number as each value is assigned to each of cells # 1 to # 7.

[0086] Thus, according to the present embodiment, each of a plurality of code sequences in which the sequence numbers are relatively prime and the sum of the greatest common divisors of the difference between the sequence numbers and the sequence length is minimized. Is assigned to each of a plurality of cells adjacent to each other. For this reason, according to the present embodiment, inter-cell interference can be suppressed.

In the present embodiment, the method of calculating the greatest common divisor between the sequence number difference of the code sequences and the sequence length and allocating the code sequence based on the calculated greatest common divisor has been described. The maximum cross-correlation value between code sequences shown in Equation (5) may be calculated, and the code sequence may be assigned based on the calculated maximum cross-correlation value. That is, by assigning each of a plurality of code sequences whose sequence numbers are relatively prime and the sum of mutual maximum cross-correlation values is minimized to each of a plurality of cells adjacent to each other, Similarly, inter-cell interference can be suppressed.

[0088] Also, in the present embodiment, a method of allocating each of a plurality of code sequences to each of a plurality of cells has been described. However, in a simple example, two sequence numbers are relatively prime, Each of the two code sequences having the sequence number that minimizes the greatest common divisor between the difference between the two sequence numbers and the sequence length is assigned to each of two adjacent cells.

[0089] Further, the greatest common divisor between the code sequences assigned to these two cells and the difference between each of the code sequences assigned to these two cells and the sequence length N is relatively prime. A code sequence having a sequence number that minimizes the sum of is assigned to one cell adjacent to these two cells.

In this embodiment, variable Min is set to NX (K + 1) XK / 2! In ST401! = Ν X 7 X 6/2! The force variable Min described as an example of initializing to NX (K + l) Χ Κ / 2! = Ν Χ 7 Χ 6/2! It may be initialized to a larger value.

[0091] The embodiments of the present invention have been described above.

[0092] In the above embodiment, a method of assigning code sequences to a plurality of cells adjacent to each other has been described. However, a cellular radio that configures a plurality of sectors in one cell using a directional antenna of a base station. In a communication system, interference between sectors in the same cell is relatively small and need not be considered.Therefore, when a code sequence is assigned to each sector in the same cell, intra-cell interference is not considered. Only the interference with each sector of the neighboring cell needs to be considered. According to this, since the number of code sequences involved in the allocation procedure calculation can be reduced, the calculation amount in the allocation procedure can be reduced.

[0093] August 2006 Patent application 2006-182234 of this application The disclosure of the specification, drawings and abstract contained in this application is incorporated herein by reference.

Industrial applicability

The code sequence allocation method according to the present invention can be applied to a cellular radio communication system or the like.

Claims

The scope of the claims

[1] A code sequence allocating method for allocating ZCZ—GCL code sequence ^ (k) shown in Equation (1) to! / Of a plurality of cells constituting a cellular radio communication system,

Land _{_{c r (k) = a r}} (κ) b t {k mod m),

a _r (k) = _± ^ (νπΗκΐ _{2) / 2 +} , bk)

W _N ^r = exp (^ jlnr / N) where r is a sequence number and is an integer that is relatively prime to N.

N: Indicates the code sequence length and is a non-prime integer.

m:

Any integer that satisfies

s: Any integer.

t: Any integer.

N = 0, 1, ..., N-1

= 0, l ".., w_l

a _r (k): Carrier sequence consisting of ZC sequences.

q: Any integer.

, (A): Modulation sequence. Among the code sequences C (k) generated by the equation (1), each of the code sequences already assigned to a plurality of second cells adjacent to the first cell is relatively prime to r, and Assigning to the first cell a first code sequence having r that minimizes the sum of the greatest common divisors of N and the difference between each of the code sequences already assigned to the second cell of

Code sequence allocation method.

[2] A plurality of code sequences are already assigned to each of the plurality of second cells,

Of the code sequence C (k) generated by the equation (1),

Each of the code sequences already assigned to the plurality of second cells and each r The difference between r of each of the code sequences already assigned to the plurality of second cells and the greatest common divisor of N is less than the difference between r of the first code sequence and N. R is the greatest common divisor,

In addition, the sum of the greatest common divisor between the difference between r and N of all the code sequences and the greatest common divisor of N is the result of adding the greatest common divisor between r and N of the first code sequence to the minimum. Further assigning to the first cell a second code sequence having r

The code sequence allocation method according to claim 1.

[3] Each of the first cell and the plurality of second cells is divided into a central area and a peripheral area,

A code sequence is already assigned to each peripheral area of the plurality of second cells, and the first code sequence is assigned to the peripheral area of the first cell;

The second code sequence having r which is relatively prime to r of the first code sequence and has the smallest common divisor between N and the difference between r of the first code sequence and the center of the first cell Assigned to the area,

The code sequence allocation method according to claim 1.

[4] A code sequence allocating method for allocating the ZCZ—GCL code sequence C (k) shown in Equation (1) to any one of a plurality of cells constituting the cellular radio communication system,

[Equation 2]

c _r (k) = a _r (k) b ^ k mod m),

_Q (n) = + Hk + N mod 2) / 2 + qk

t L ... (1) b ^ k) = w k or I) = (- 1),

W _N ^r = exp (j2 ^ IN) where / ·: indicates the sequence number and is an integer that is relatively prime to.

N: Indicates the code sequence length and is a non-prime integer.

m:

Any integer that satisfies

s: Any integer.

t: Any integer.

0, 1, ..., N-1

/ = 0, l ".., w— l

a _r (k): A carrier sequence consisting of ZC sequences.

q: Any integer.

b _t (k) Modulation sequence. Calculate the maximum cross-correlation value between code sequences according to equation (2),

Maximum cross-correlation value = (the greatest common divisor between r and N) Χ Χ · '· (2)

Among the code sequences C (k) generated by the equation (1), each of the code sequences already assigned to a plurality of second cells adjacent to the first cell has a sequence number that is relatively prime to r. In addition, a first code sequence having a minimum sum of maximum cross-correlation values with each of the code sequences already assigned to the plurality of second cells is assigned to the first cell.

Code sequence allocation method.

[5] A plurality of code sequences are already assigned to each of the plurality of second cells,

Of the code sequence C (k) generated by the equation (1),

A sequence number that is relatively prime to r of each of all the code sequences already assigned to the plurality of second cells;

Maximum mutual interaction with each of all code sequences already assigned to the plurality of second cells The maximum cross-correlation value with the first code sequence is smaller than the correlation value

In addition, the second code sequence having the minimum result obtained by adding the maximum cross-correlation value with the first code system IJ to the sum of the maximum cross-correlation values with each of all the code sequences is the first code sequence. Assign further to the cell,

The code sequence allocation method according to claim 4.

[6] Each of the first cell and the plurality of second cells is divided into a central area and a peripheral area,

A second code sequence having a sequence number that is relatively prime to r of the first code sequence and having a maximum maximum cross-correlation value with the first code sequence is assigned to the central area of the first cell. ,

The code sequence allocation method according to claim 4.

[7] A code sequence allocating method for allocating the ZCZ—GCL code sequence C (k) shown in Equation (1) to any one of a plurality of cells constituting the cellular radio communication system,

[Equation 3]

c _r (k) = _r (k) b _t (k mod m),

a _r (k) = ^ ^{(t + iVmod 2) 2+} ^, b _t (k)

_{^{W N r = exp {jl r}} IN) However, indicates sequence numbers, and integers relatively prime.

N: Indicates the code sequence length and is a non-prime integer.

m: Any integer that satisfies N = sXm2 and N = tXm.

5: Any integer.

t: Any integer.

k =, \, ..., N- \

/ = 0, l, ..., w-l

a _r {k): career series consisting of ZC sequence.

q: Any integer.

b k): modulation sequence. In the code sequence C (k) generated by the equation (1), two r are relatively prime, and the first common divisor between the difference between the two r and N is the smallest. Assign each of the two code sequences of the code sequence and the second code sequence to each of the two cells of the first cell and the second cell adjacent to each other.

Code sequence allocation method.

[8] Of the code sequences C (k) generated by the equation (1), each of the two code sequences is relatively prime, and the difference between each of the two code sequences and r is N Assigning a third code sequence having r with the smallest sum of the greatest common divisors to the third cell further adjacent to the two cells,

The code sequence allocation method according to claim 7.

[9] Of the code sequences C (k) generated by the equation (1), each of the two code sequences is relatively prime and the difference between each of the two code sequences and r is N And the greatest common divisor The third code sequence having r with the smallest sum is

Of the two cells, the difference between the r of each of the two code sequences and the r of the third code sequence is further assigned to the smaller of the greatest common divisors of N,

The code sequence allocation method according to claim 7.

Each of the two cells is divided into a central area and a peripheral area,

Assigning each of the two code sequences of the first code sequence and the second code sequence to a peripheral area of each of the first cell and the second cell;

Of the code sequence C (k) generated by the equation (1),

R which is relatively prime to r of the first code sequence assigned to the surrounding area of the first cell and which minimizes the greatest common divisor between N and the difference between r of the first code sequence and Having a third code sequence assigned to the central area of the first cell,

R which is relatively prime to r of the second code sequence assigned to the peripheral area of the second cell, and which minimizes the greatest common divisor between N and the difference of r of the second code sequence. A fourth code sequence is assigned to the central area of the second cell,

The code sequence allocation method according to claim 7.