KR101356492B1 - Method For Generating and Allocating Sequence Based On Grouping Of Resource Block - Google Patents

Abstract

The present invention relates to a method for generating and assigning a resource block grouping based sequence. According to the present invention, after grouping a predetermined number of resource blocks, by generating and allocating a sequence of a fractional length greater than the number of subcarriers included in each group and a fractional length less than the number of subcarriers included in each group, While increasing the number of sequences, it is possible to prevent deterioration of correlation characteristics and PAPR characteristics of the sequences.

Create sequence, assign sequence

Description

Method for Generating and Allocating Sequence Based On Grouping Of Resource Block}

1 is a diagram for explaining a method of generating a sequence according to a cut-type sequence generation method;

2 is a diagram for explaining a method of generating a sequence according to a padding-type sequence generation method;

3 is a diagram for explaining a sequence generation and allocation method that can be used in an SB usage structure according to one embodiment of the present invention;

4 is a diagram for explaining a sequence generation and assignment method that can be used in an LB dedicated structure according to an embodiment of the present invention.

5 is a view for explaining an example of applying a sequence generation and assignment method that can be used in an SB usage structure according to an embodiment of the present invention to various combinations of RB groupings.

FIG. 6 is a view for explaining an example of applying a sequence generation and assignment method that can be used in an LB dedicated structure according to an embodiment of the present invention to various combinations of RB groupings. FIG.

The present invention relates to a method for generating and assigning a sequence used in a wireless communication system. In particular, the present invention relates to a method for generating and assigning a CAZAC sequence widely used in an OFDM wireless communication system based on resource block grouping.

There are various sequences used to transmit control information including ID and synchronization information for distinguishing signals in a communication system. However, in the current 3GPP LTE system, a constant amplitude zero auto-correlation (CAZAC) sequence is used. It is the basis. The CAZAC sequence can be used for various IDs and information by using this sequence. These channels include synchronization channels (e.g., primary SCH, secondary SCH, BCH) for downlink synchronization, synchronization channels (e.g., RACH) for uplink synchronization, pilot channels , Data pilot, channel quality pilot). In addition, the above-described CAZAC sequence may be used for scrambling.

Two types of CAZAC sequences are used: GCL CAZAC and Zadoff-Chu CAZAC. These are in conjugate complex numbers, and the GCL CAZAC can be obtained by taking the conjugate complex number of Zadoff-Chu. Zadoff-Chu CAZAC is given as follows.

Here k denotes a sequence index, N denotes a length of a CAZAC sequence to be generated, and M denotes a sequence ID.

When a Zadoff-Chu CAZAC sequence given by Equations (1) and (2) and a GCL CAZAC sequence having a conjugate complex number relationship with the Zadoff-Chu CAZAC sequence are expressed by c (k; N, M), they all have the following three characteristics.

Equation 3 shows that the CAZAC sequence always means 1, and Equation 4 shows that the auto-correlation function of the CAZAC sequence is represented as a delta function. Here, autocorrelation is based on circular correlation. Also, Equation 5 shows that the cross-correlation is always constant.

Meanwhile, when a length to be applied in a system to which a CAZAC sequence is conventionally applied is L, a CAZAC sequence is generated by setting N of the Equation 1 or Equation 2 to N = L regardless of the CAZAC sequence. If you do, the following problems may occur.

Specifically, referring to the characteristics of the CAZAC sequence generated with a specific length L for a while, if L is not a prime number, the generated CAZAC sequence is a sequence ID up to M = 1,2, ..., L-1 You can do this, but duplicate code is generated. In other words, the actual number of different codes is less than L-1. On the other hand, if L is a prime number, L-1 different codes are generated. Therefore, if the length of codes to be applied to the system is not a small number and the number of codes to be used is large, there may be a problem in cell planning.

In particular, the size of a resource block which is a basic transmission unit in the uplink structure of 3GPP LTE, which is currently discussed, corresponds to 12 subcarriers. This is a case where a long block (LB) is applied as a reference in the current subframe structure described in TR 25.814, while the length of a sequence that can be used for a short block (SB) is 6.

As described above, when the CAZAC sequence is applied to the LB and the SB, the length of the sequence is not a fractional length. Therefore, the number of sequences having different indexes can be generated in each case of LB and SB. Very small with four and two. This is because, as described above, when the length of the CAZAC sequence is not a prime number, the number of sequences is determined according to the number of mutually prime natural numbers less than the length. Therefore, there is a demand for a technique for increasing the number of sequences when the resource block to which the sequence is applied is not a fractional length.

In order to solve the above problems, an object of the present invention is to generate and allocate a sequence having a small length based on resource block grouping to secure the number of sequences in a limited resource block environment, while maintaining the correlation characteristics and low PAPR of the CAZAC sequence. To provide a way to maintain the characteristics.

According to an aspect of the present invention, there is provided a method for generating a sequence, the method including: grouping a predetermined number of adjacent resource blocks (RBs); Generating a sequence having a fractional length greater than or equal to the number of subcarriers included in each of the resource blocks as a first type sequence to be applied to a first resource block among the grouped resource blocks; And generating a sequence having a fractional length less than the number of subcarriers included in each of the resource blocks as a second type sequence to be applied to a second resource block of the grouped resource blocks.

In addition, the sequence allocation method according to another embodiment of the present invention, generating a sequence having a fractional length of the number of subcarriers included in the resource block as a first type sequence; Generating a sequence having a fractional length less than the number of subcarriers included in the resource block as a second type sequence; And allocating the first type sequence and the second type sequence to adjacent resource blocks.

In this case, the sum of the lengths of the first type sequence and the second type sequence may be generated to be equal to the number of subcarriers included in the predetermined number of adjacent resource blocks, and the first type sequence is included in the resource block. The second type sequence may be generated to have a maximum fractional length less than the number of subcarriers included in the resource block.

In addition, the first resource block and the second resource block may be allocated to different users.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form around the core functions of each structure and device in order to avoid obscuring the concepts of the present invention. In the following description, the same components are denoted by the same reference numerals throughout the specification.

As described above, in the case of the CAZAC sequence, a total of L-1 sequences can be generated when the length (L) of the required sequence is a prime number. However, if the length of the sequence is not a prime number, . As such, when the sequence length L required by the communication system due to the length of the resource block is not a fractional length, the following scheme may be proposed as a solution to solve this problem.

First, there is a truncated sequence generating method.

1 is a diagram for explaining a method of generating a sequence according to a cut type sequence generation method.

In this method, when the length L required by the system is not the fractional length, the sequence is generated by setting the decimal number X larger than L to N in the above Equation 1 or Equation 2. Thereafter, a sequence longer than L in the generated sequence is truncated to L length.

According to the truncation sequence generation method as described above, the number of sequences can be extended. However, since the sequence generated by the aforementioned method truncates a part of the sequence, the delay is zero in autocorrelation and cross-correlation characteristics as shown in Equation 4 above. If only the value of 1, in other cases the property of having a value of 0, and the characteristic that the cross-correlation value always has a constant as shown in Equation 5 deteriorates. In addition, when the sequence having a poor correlation property is actually removed, the number of the sequence cannot be guaranteed to be L-1. In addition, by cutting off a part of the generated CAZAC sequence, degradation of the CAZAC sequence having a low PAPR characteristic may also occur.

Meanwhile, in order to solve the above problems, a technique of generating a CAZAC sequence by selecting a maximum fraction length X less than or equal to the length L required in the communication system, and inserting a padding part in a portion having the length of LX Is being proposed. Hereinafter, such a method will be referred to as a padded sequence generation method for convenience of description.

2 is a diagram for explaining a method of generating a sequence according to a padding-type sequence generation method.

According to the padding-type sequence generation scheme as described above, when the length L required by the system is not a fractional length, the largest fraction X among the fractions smaller than L is set as N in Equation 1 or Equation 2. Create Thereafter, 0 is padded by the generated sequence C1 by a length C2 corresponding to L-X to generate a sequence having an L length.

In the padding-type sequence generation method, a part of the generated sequence is divided as shown in FIG. 1 by dividing the sequence by setting the correlation calculation portion of the sequence as the C1 portion in FIG. 2 There is an advantage that the deterioration of the autocorrelation and the cross-correlation property does not occur. However, when the overall length of the sequence to be applied is also deteriorated in the correlation characteristic and the PAPR characteristic due to the padding portion C2 that is also zero.

Therefore, in one embodiment of the present invention, when the number of subcarriers included in the resource block (RB) is not a small number, a predetermined number of adjacent RBs are grouped in the frequency domain in resource allocation, and based on such grouping, each RB We propose a method for generating and allocating a fraction length sequence larger than the number of subcarriers included in a sequence and a fraction length sequence smaller than the number of subcarriers. As such, when each sequence is generated based on the decimal length, a sufficient number of sequences can be generated, and deterioration in correlation and PAPR characteristics of the CAZAC sequence can be prevented by using the generated sequence itself without using cutting or padding. can do.

As described above, the embodiment of the present invention can be applied to not only a subframe structure in which LB and SB exist (LB & SB use structure) but also a subframe structure in which only LB exists (LB only structure) in 3GPP LTE system. . Therefore, hereinafter, the method for generating and assigning the sequence according to the embodiment of the present invention will be specifically described in the case of applying to the LB & SB using structure and the case to be applied to the LB dedicated structure.

3 is a view for explaining a sequence generation and allocation method that can be used in the SB usage structure according to an embodiment of the present invention.

That is, one embodiment of the present invention shown in FIG. 3 includes 12 subcarriers in the LB for transmitting data within 1 RB, and 6 subcarriers in the SB for transmitting pilot. A method of generating and assigning a fractional length sequence to each by grouping adjacent RBs is shown.

Specifically, when the SB constituting the 1RB in FIG. 3 is composed of N subcarriers, in principle, a sequence having a length N may be allocated, but when the number N of subcarriers included in the SB is 6, N-1 And a method of assigning a sequence having a length of N-1 to one RB and allocating a sequence having a length of N + 1 to another RB at a point where N + 1 is 5 and 7 as a fractional length. Suggest.

According to this method, since it is possible to generate a CAZAC sequence having a decimal length, it is possible to increase the number of generated sequences, and to maintain the correlation characteristics of the CAZAC sequence by using the generated sequence itself without cutting or padding This has the advantage of maintaining good PAPR characteristics.

4 is a view for explaining a sequence generation and allocation method that can be used in the LB dedicated structure according to an embodiment of the present invention.

That is, one embodiment of the present invention shown in FIG. 4 includes two adjacent RBs according to one embodiment of the present invention when 12 subcarriers are included in the LB for data transmission and pilot transmission in one RB. Grouping shows how to generate and assign a fractional length sequence to each. In the case of a dedicated LB structure, the LB may correspond to a general OFDM symbol.

In detail, when an OFDM symbol constituting 1RB of FIG. 4 is configured with N subcarriers, a sequence having a length N may be allocated in principle, but when the number N of subcarriers included in each OFDM symbol is 12, Since N-1 and N + 1 are decimal lengths as 11 and 13, two adjacent RBs are grouped to allocate a sequence having an length of N-1 to one RB and a sequence having a length of N + 1 to another RB. Suggest a way to assign.

According to this method, as in the case of FIG. 3, it is possible to generate a CAZAC sequence having a fractional length, thereby increasing the number of generated sequences, and using the generated sequence itself without cutting or padding. It has the advantage of maintaining the correlation characteristics of, and can maintain good PAPR characteristics.

3 and 4 described above, neighboring RBs may also be allocated to two different UEs. Thus, when a sequence is allocated to two UEs to which the neighboring RBs are allocated, N-for a length N of RBs is assigned to one UE. A fractional length sequence of 1 may be allocated to another UE in a fractional length sequence of N + 1. However, such a rule is that when the number of RBs allocated to each UE increases or the combination of the number of RBs allocated to each UE varies, a sequence having a length of exactly N-1 and N + 1 cannot be allocated. May be present. In this case, the sequence length allocated to 2 UEs under the same condition that the total length of the entire sequence is equal to the total length of the entire grouped region has the effect as described above by allocating the maximum fractional length less than N and the minimum fractional length greater than N. Can be. This case will be described in more detail below. In addition, this is further described by allocating a sequence length allocated to two or more UEs under the same condition as the total length of the entire grouped region even in cases other than 2 UEs by a combination of a maximum fraction length of less than N and a minimum fraction length of N or more. It can have the same effect as one.

5 is a view for explaining an example of applying a sequence generation and assignment method that can be used in an SB usage structure according to an embodiment of the present invention to various combinations of RB groupings.

Specifically, in FIG. 5, in the SB usage structure, when 1RB is allocated to one UE and 2RBs adjacent to another UE are grouped, the groups are grouped to generate and allocate a sequence based on the decimal length according to the above-described embodiment of the present invention. It shows how to do it.

In the SB utilization structure, the number of subcarriers included in one RB in the SB corresponds to six, and the number of subcarriers included in the two RBs corresponds to twelve. Therefore, in this case, if a CAZAC sequence having a length of 5 corresponding to the length N-1 is generated for a UE using 1 RB and a CAZAC sequence having a length 13 corresponding to the length N + 1 is allocated to a UE using 2 RB, Length based CAZAC sequences may be used.

FIG. 6 is a view for explaining an example of applying a sequence generation and assignment method that can be used in an LB dedicated structure according to an embodiment of the present invention to various combinations of RB groupings.

Specifically, in FIG. 6, in the case of allocating 1RB to one UE and 2RBs adjacent to another UE in the LB-only structure, the groups are grouped to generate and allocate a sequence based on the decimal length according to the above-described embodiment of the present invention. It shows how to do it.

In the LB-only structure, the number of subcarriers included in one RB corresponds to 12, and the number of subcarriers included in 2 RB corresponds to 24. Accordingly, in this case, when a CAZAC sequence having a length of 13 corresponding to a length N + 1 is generated for a UE using 1 RB, and a CAZAC sequence having a length of 23 corresponding to a length N-1 is generated and assigned to a UE using 2 RB, Length based CAZAC sequences may be used.

That is, in one embodiment of the present invention with the example shown in Figs. You can find the maximum prime number or the minimum prime number above the length of each region, and create and assign sequences based on it. The length of the sequence allocated in this manner may not necessarily be N-1, N + 1, and the sequence lengths allocated in the SB using structure and the LB dedicated structure according to various forms of grouping may be represented by the following table. .

That is, in the case of grouping adjacent 1RB and 2RB in Table 1, a sequence of lengths 5 and 13 may be generated and allocated in the SB-using structure as shown in FIG. 5, and in the LB-only structure, as shown in FIG. A sequence of 13 and 23 can be created and assigned. Similarly, in the case of grouping 1RB and 3RB, a sequence of lengths 5 and 19 can be generated and allocated in the SB-using structure, and a sequence of lengths 11 and 37 can be generated and assigned in the LB-only structure.

Table 1 described above shows a combination of sequence lengths generated and allocated according to an embodiment of the present invention when two regions to be grouped are two regions and the number of RBs included in each region is different. In a similar manner, when two adjacent regions are grouped and the number of RBs included in each region is the same, a sequence may be generated by the following combination.

That is, in the case of grouping adjacent 1RBs in Table 1 and assigning them to each UE, a sequence of lengths 5 and 7 can be generated and allocated as shown in FIG. 3 in the SB usage structure. As shown in the drawing, sequences 11 and 13 may be generated and allocated. Similarly, in the case of grouping adjacent 2RB regions, a sequence of lengths 11 and 13 can be generated and allocated in the SB-using structure, and a sequence of lengths 19 and 29 can be generated and assigned in the LB-only structure. In this case, for the length N of each region, the length of the sequence may not satisfy the lengths of N-1 and N + 1. Sequences can be generated according to the above-described embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the present invention has been presented for those skilled in the art to make and use the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

According to the RB grouping-based sequence generation and allocation method according to an embodiment of the present invention as described above, by generating a group of a predetermined number of RBs to generate and / or assign a sequence having a fractional length greater than or less than each region length A large number of sequences can be created and used.

In addition, according to the above-described method, by using the generated sequence itself to have a decimal length without cutting or padding the generated sequence, it is possible to prevent degradation of the correlation characteristics and PAPR characteristics of the sequence in the case of the CAZAC sequence have.

Claims (5)

Grouping a predetermined number of adjacent resource blocks (RBs); Generating a sequence having a fractional length greater than or equal to the number of subcarriers included in each of the resource blocks as a first type sequence to be applied to a first resource block among the grouped resource blocks; And Generating a sequence having a fractional length less than the number of subcarriers included in each of the resource blocks as a second type sequence to be applied to a second resource block of the grouped resource blocks. The method of claim 1, And the sum of the lengths of the first type sequence and the second type sequence is generated to be equal to the number of subcarriers included in the predetermined number of adjacent resource blocks. The method of claim 2, The first type sequence is generated to have a minimum fraction length greater than or equal to the number of subcarriers included in the resource block. And the second type sequence is generated to have a maximum fraction length less than the number of subcarriers included in the resource block. 4. The method according to any one of claims 1 to 3, And the first resource block and the second resource block are assigned to different users from each other. Generating a sequence having a fractional length of at least the number of subcarriers included in the resource block as a first type sequence; Generating a sequence having a fractional length less than the number of subcarriers included in the resource block as a second type sequence; And Allocating the first type sequence and the second type sequence to adjacent resource blocks.

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