KR101306716B1 - Method For Transmitting and Receiving Signals Using Prime Number Length Sequence - Google Patents

Abstract

In the following description, a method of transmitting and receiving a signal based on a decimal length sequence is provided. That is, the subcarriers in a certain number of resource blocks (RBs) are divided into a predetermined number of channels including a prime number of subcarriers, and a signal is transmitted through the predetermined number of channels. A method is provided, which may be advantageous in multi-cell design by securing the number of available sequences.

Such a method may be used for an uplink control channel using SC-FDM, and may be particularly advantageous for a channel structure for transmitting a control signal without data.

Control channel, fractional length

Description

Method for Transmitting and Receiving Signals Using Prime Number Length Sequence}

1 is a schematic diagram showing a configuration of a transmitting end of a typical SC-FDM communication system.

2 illustrates a channel structure that may be used when transmitting only a control signal without data.

3 illustrates a channel structure that may be used when data and control signals are transmitted together.

4 is a diagram for explaining a method for generating a sequence according to a truncated sequence generation method for generating a decimal length sequence;

FIG. 5 is a diagram for describing a method of generating a sequence according to a padded sequence generation method for generating a decimal length sequence; FIG.

6 is a diagram illustrating a structure in which control channels by resource block division are arranged one by one at both ends of a system bandwidth according to one embodiment of the present invention;

7 is a diagram illustrating a structure in which a control channel by resource block division is disposed at one end of a system bandwidth according to an embodiment of the present invention.

8 is a diagram illustrating a structure in which a predetermined number of resource blocks are disposed at both ends of a system bandwidth according to an embodiment of the present invention, and a control channel is formed by dividing these resource blocks.

FIG. 9 illustrates a structure in which a predetermined number of resource blocks are grouped into a plurality of groups at both ends of a system bandwidth according to an embodiment of the present invention, and a control channel is formed by division of these grouped resource blocks. .

The present invention relates to a method for transmitting and receiving a signal in a mobile communication system, and more particularly, the present invention relates to a method for transmitting and receiving a signal based on a decimal length sequence.

The present invention can be applied to both uplink and downlink channels of any communication method for transmitting a signal through a predetermined sequence, but in the following, in particular, the terminal is suitable for the SC-FDM structure in transmitting a control signal in uplink but is also suitable for multi-cell deployment. This paper focuses on proposing a channel structure for transmitting control signals without problems in multi-cell deployment. In addition, the following detailed description of the present invention is to provide a method for transmitting and receiving a signal by ensuring the maximum number of sequences applicable to the corresponding channel through the channel structure proposed in accordance with the present invention.

To this end, the general SC-FDM method will be described.

When the terminal transmits a control signal to the base station, one of the most important points is coverage. That is, the bandwidth of the signal transmitted by the terminal is not large, but the method of centralizing and transmitting power in one place is important, and it is preferable that the change width (PAPR) of the transmitted signal is also small. To this end, 3GPP LTE has been discussed to use SC-FDM (Single Carrier Frequency Divideion Mutiplexing) as the uplink signal transmission.

1 is a schematic diagram illustrating a configuration of a transmitting end of a general SC-FDM communication system.

SC-FDM is a transmission method that makes a small amount of change in a signal, and has a wider coverage effect when using the same power amplifier. As can be seen from the configuration of the transmitter of the SC-FDM scheme as shown in Figure 1, the biggest feature of the SC-FDM is that in the portion where the transmission signal is first spread (spreading) to the DFT, and then generates the transmission signal The method focuses on frequency bands and maps them. The generated signal has the same effect as that transmitted through a single carrier. Thus the generated signal is characterized by having a small PAPR.

In designing a control signal used in any communication system including the SC-FDM communication system described above, it is necessary to consider how the terminal should generate and send the control signal.

First, in a multi-cell environment, collision may occur when adjacent cells use the same sequence or uplink resource. As a way to distinguish this, it is possible to envisage the use of different resources according to predetermined rules between cells. However, this may be too difficult for cell planning in the actual system deployment stage. Can be. On the other hand, for example, a scheme for achieving randomization effect through frequency hopping, sequence hopping, etc. may be considered. It may not be appropriate.

Therefore, the best solution is to use different orthogonal or close sequences between cells to distinguish different terminals using CDM. Such an implementation does not require cell planning and naturally allows resource sharing between systems at minimal cost. However, the proper number of spreading sequences is necessary for this purpose, but no clear description of a method for using a sufficient number of sequences without degrading the performance of the sequence is not provided.

In order to solve the above problems, the following detailed description of the present invention is to provide a channel structure that can ensure the maximum number of available sequences, thereby providing a method for transmitting and receiving signals.

According to an aspect of the present invention, there is provided a signal transmission method including a predetermined number of subcarriers in a predetermined number of resource blocks (RBs) including a prime number of subcarriers. Dividing into a; and transmitting a signal through the divided number of channels.

In this case, the signal transmitted through the predetermined number of channels is expressed using a predetermined sequence, and when the predetermined sequence has a decimal length, the predetermined sequence may be a sequence in which the number of distinguishable sequences is maximized.

Further, the predetermined number of channels divided may be distributed at both ends of the system bandwidth or disposed at either side of the system bandwidth.

A control signal transmission method according to another aspect of the present invention for achieving the above object is a communication system for allocating a predetermined number of resource blocks (RB) for the control channel at either or both ends of the system bandwidth; CLAIMS 1. A method of transmitting a control signal in a method comprising: dividing subcarriers in the predetermined number of resource blocks allocated for the control channel into a predetermined number of channels including a prime number of subcarriers; And transmitting a control signal through the divided number of channels.

In this case, the communication system may include a plurality of the predetermined number of resource blocks allocated for the control channel at both ends or either side of the system bandwidth, and specifically, the communication system is SC-FDM (Single Carrier-Frequency). A divisional multiplexing communication system, and the control signal may be expressed using a constant amplitude zero auto correlation (CAZAC) sequence.

On the other hand, the control signal transmission and reception method according to another aspect of the present invention for achieving the above object comprises the steps of preparing a control signal represented by using a predetermined sequence; And transmitting and receiving the control signal through a control channel, wherein the control channel includes subcarriers having a small number of subcarriers in a predetermined number of resource blocks (RBs). Characterized in that divided into a predetermined number of channels including a.

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, the present invention provides a channel structure capable of maximizing the number of available spreading sequences to support a multi-cell environment, and provides a method of transmitting and receiving a signal through the same. Therefore, in the following description of the present invention, in order to provide a control channel structure capable of maximally generating a distinguishable sequence without degrading performance in multiple accesses while maintaining the SC-FDM, a control channel generally used in the SC-FDM scheme The structure will be described and a sequence, in particular a CAZAC sequence, which can be used as a control signal transmitted through such a channel will be described.

There is a part to be considered when transmitting a control signal in the above-described SC-FDM scheme. First, when transmitting a control signal, different channel structures may be used as follows depending on whether or not there is data.

2 is a diagram illustrating a channel structure that may be used when only a control signal is transmitted without data.

When transmitting the control signal, when there is no data to be sent together, as shown in FIG. Specifically, the control channel region allocated for the control signal transmission without data transmission may be at both ends of the system band as shown in FIG.

The terminal transmitting only the control signal according to the control channel formed as described above may demodulate and transmit the control signal in the SC-FDM format to the allocated area. The method of transmitting a control signal in this allocated area may take the form of FDM or code division multiplexing (hereinafter, referred to as "CDM") between the control signals of the terminal in the allocated area.

3 illustrates a channel structure that may be used when data and control signals are transmitted together.

Even when data and control signals are transmitted together, some bands of the system band may be divided for FDM scheme and allocated for control channel transmission as shown in FIG. 2. In this case, the transmission scheme cannot be viewed as an SC-FDM scheme. This corresponds to a multi-carrier transmission scheme. Accordingly, even when data and control signals are simultaneously transmitted, data and control signals are transmitted together through DFT spreading in order to maintain the SC-FDM scheme and reduce the PAPR of the transmission signals. In this case, the method of combining the data and the control signal may be time division multiplexing (“TDM”), CDM, or modulation-based transmission. FIG. 3 illustrates that the control signal and the data are transmitted in the TDM method.

In the structure shown in FIG. 3, a method of increasing coverage in the absence of a control signal may be similarly implemented. When it is necessary to send a control signal robustly, a method of repeatedly inserting a specific control signal in each OFDM symbol is required. to be. This can increase the power of the control signal approximately 10 * log ₁₀ (12) = 10.8 dB.

In the above-described control channel structure, an embodiment of the present invention will be described based on the case where only a control signal is transmitted without data. That is, the control channel is specifically designed to efficiently secure the number of available sequences in the basic control channel structure as shown in FIG. 2, and a method of transmitting and receiving a signal will be described.

In addition, the method according to the following specific embodiments is described under the premise of maintaining the SC-FDM scheme that can bring about a PAPR reduction effect in the uplink as a transmission scheme, but the transmission scheme need not be limited to this, and the situation of the system In this case, a more advantageous transmission method can be used.

On the other hand, the CAZAC sequence, particularly the Zadoff-Chu (ZC) sequence is a prominent sequence used for the control signal transmitted through the control channel as shown in FIG. Hereinafter, the above-described CAZAC sequence will be described.

As the CAZAC sequence, two kinds of the aforementioned Zadoff-Chu CAZAC and GCL CAZAC are used. 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.

On the other hand, when the length to be applied in the system applying the CAZAC sequence is L, when the CAZAC sequence to generate a CAZAC sequence by setting N in the equation 1 or 2 to N = L regardless of the L value 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.

In summary, a CAZAC sequence including a ZC sequence can use the most sequence when the sequence length L is a prime number, and when it is not a prime number, it is possible to generate a sequence that can be distinguished only by the L and M values that are prime. Therefore, in order to secure the number of sequences, it is better to make the sequence small so as to be the length.

Currently, in 3GPP LTE, when only the control signal is transmitted without data, the control channel as shown in FIG. 2 is set and used. In this case, the basic allocation unit allocated to the signal is called a resource block (hereinafter, referred to as a "RB"), and the number of subcarriers included in one RB is 12, not a decimal number.

In general, when a spreading sequence is applied in the frequency domain, the number of available sequences may be determined according to the number of subcarriers used, and it may be determined whether the multi-cell environment can be supported. In order to apply a sequence in units of resource blocks including subcarriers other than the following, the following scheme may be used.

First, the method by the truncated sequence generating method which produces | generates a sequence by the fractional length larger than a required length, and cut | disconnects length more than a required length is demonstrated.

3 is a diagram for describing a method of generating a sequence according to a truncated 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 greater than L to N in Equation 1 or Equation 2 above. 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 portion of the sequence, the correlation property of the CAZAC sequence may be degraded. 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 in the characteristics of the CAZAC sequence having a low PAPR.

Secondly, in order to solve the above problems, a CAZAC sequence is generated 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 part having the length of LX. The technique to say is proposed. Hereinafter, such a method will be referred to as a padded sequence generation method for convenience of description.

4 is a diagram for describing a method of generating a sequence according to a padded 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, the generated sequence C1 is padded with a length C2 corresponding to L-X to generate a sequence having an L length.

In the case of the padding-type sequence generation method as described above, a portion of the generated sequence is cut out as shown in FIG. There is an advantage that the degradation of the correlation characteristics may 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.

Finally, even if the length L required by the system is not a fractional length, the sequence may be generated as it is as N value of Equation 1 as it is. In this case, as described above, the number of sequences generated to be distinguishable may be very small. However, when directly generating the sequence length to be used, the correlation characteristics between the sequences and the uniformity of the signal in the time / frequency domain (for example, PAPR, cubic metric, etc.) have good characteristics.

Therefore, in one embodiment of the present invention, in order to properly transmit and receive a control signal transmitted when there is no data in a multi-cell environment, a control channel structure is adjusted rather than adjusting a sequence generation itself according to a non-fractional length channel. It is proposed to set to favor the number of sequences.

That is, in order to make use of good CAZAC sequence characteristics, specifically ZC sequences, as described above, the following matters should be considered when generating a control signal channel. First, since the number of subcarriers tends to be equal to the length of the sequence, it is preferable to make the number of subcarriers of the channel to be a small number when generating one control signal channel.

In summary, in one embodiment of the present invention, when a control signal is transmitted using a sequence that is advantageous for securing the number of sequences when the decimal length has a minority length, such as a CAZAC sequence, a corresponding number of subcarriers in a predetermined number of RBs are assigned to the corresponding control channel. It is proposed that the formed by dividing into a predetermined number of channels including the sub-carrier of. Accordingly, the signal transmission method according to an embodiment of the present invention proposes to transmit and receive a signal using the above-described sequence through a channel divided to include a small number of subcarriers.

Hereinafter, based on the control channel structure shown in FIG. 2 when transmitting a control signal without data in uplink of a communication system using SC-FDM, which is assumed in the above-described embodiment of the present invention in 3GPP LTE, It demonstrates concretely as follows. However, the specific structure of the control channel and the method for transmitting and receiving signals according to the present invention are not necessarily limited to the illustrated structure, and those skilled in the art will appreciate that the present invention can be applied to any structure as long as it includes only the claims of the present invention.

6 is a diagram illustrating a structure in which control channels by resource block division are arranged one by one at both ends of a system bandwidth according to an embodiment of the present invention.

Hereinafter, FIG. 6 will be described assuming that one physical resource block (hereinafter, referred to as "PRB") or two PRBs are allocated for a control channel. However, three or more PRBs are allocated for the control channel. The same may be applied to the case. Specifically, assuming that 1 PRB or 2 PRBs are allocated for the control channel, and 1 PRB includes 12 subcarriers, the number of prime numbers of various combinations of these PRBs according to one embodiment of the present invention are shown in Table 1 below. The control channel may be formed by dividing into two control channels including the subcarriers, and may be divided and disposed at both ends of the system bandwidth as shown in FIG. 6. The number of subcarriers included in each control channel is represented by N _A and N _B.

Meanwhile, FIG. 6 illustrates a form in which two divided control channels are distributed at both ends of the system band as shown in Table 1, but it is not necessary to distribute the two control channels at both ends of the system.

7 is a diagram illustrating a structure in which a control channel by resource block partitioning is disposed at one end of a system bandwidth according to an embodiment of the present invention.

That is, the control channel divided to include the number of subcarriers in the combination as shown in Table 1 may be distributed at both ends of the system band as shown in FIG. 6, or may be disposed at one end of the system band as shown in FIG. 7. It may be.

6 and 7 illustrate a case in which the bandwidth BW allocated for the control channel is divided into two control channels, but the number of control channels to be divided is determined by the system. Various settings can be made according to requirements.

On the other hand, as shown in FIG. 6, non-integer PRBs (for example, a part of 1 PRB in the case of dividing 1 PRB) are used as control channels at both ends of the system band and as shown in FIG. 7. Similarly, if a divided control channel is disposed at one end of the system band, a symmetry problem may be raised. That is, a problem may occur in which power is concentrated only in a specific band within a system band.

To this end, in configuring the control channel, it may be more preferable to use the whole number of PRBs in the area where the control signal is transmitted as follows.

8 is a diagram illustrating a structure in which a predetermined number of resource blocks are arranged at both ends of a system bandwidth according to an embodiment of the present invention, and a control channel is formed by dividing these resource blocks.

That is, FIG. 8 shows a predetermined number (integer number) of PRBs arranged at both ends of the system band and divided into control channels including a small number of subcarriers in the PRB. Specifically, FIG. 8 shows N _s1 and N _s2 PRBs disposed at both ends of the system band, respectively, and control includes (N _A1 , N _B1 ) and (N _A2 , N _B2 ) subcarriers, respectively, in these PRBs. The form of dividing into channels is shown.

In FIG. 8, the number of PRBs allocated for control channels at both ends of a system band may have a combination as follows.

If the number of PRBs allocated for control channels at both ends of the system band is set as shown in Table 2 above, even in the embodiment as shown in FIG. 8, both system bands may have asymmetrical shapes. For example, the size of the control channel region on one side may be x PRB, but the size of the control channel region on the other side may be y PRB (where x? Y). Accordingly, the number of subcarriers allocated to the control channel can be arbitrarily adjusted according to the number of PRBs allocated for the control channel.

The generation of the control channel according to the number of PRBs allocated for the control channel in the system band may be divided in the manner shown in Table 1 according to the number of subcarriers given to each. Of course, if the number of PRBs allocated for the control channel is large, it is also possible to divide into a larger number of control channels instead of two control channels, wherein each control channel PRB is a sum of two fractional length control channels. Rather, it is the sum of a plurality of minority length control channels.

Table 3 below shows an example of dividing a predetermined number of PRBs into three control channels.

The sizes of the channels generated by Table 3 described above may be interchanged. The predetermined number of PRBs allocated for the control channel may also be divided into any number of control channels of four or more.

Meanwhile, when the actual system is implemented, as shown in FIGS. 6 to 8, there may not be only one control channel PRB configured with a predetermined number of PRBs in one region of the system band.

FIG. 9 illustrates a structure in which a predetermined number of resource blocks are grouped into a plurality of groups at both ends of a system bandwidth, and a control channel is formed by division of these grouped resource blocks according to an embodiment of the present invention. to be.

That is, the PRBs for control channels composed of a predetermined number of PRBs at both ends of the system band may be grouped into a predetermined number of groups in each region instead of only one control channel group. In this case, the control channel having the structure as shown in FIG. 8 repeatedly appears, or when the system band is large, the control signal may be transmitted through an arbitrary band of the system band.

As described above, a plurality of PRB groups may be divided into a plurality of control channels including a small number of subcarriers as shown in Tables 1 and 3, and FIG. 9 is divided into two control channels in each group. It is showing.

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.

For example, a signal transmitted through a channel designed in the manner proposed in the above-described embodiments of the present invention may be applied not only to a control signal but also to transmit an arbitrary signal represented by a sequence that is advantageous for securing a sequence number when having a decimal length. Can be.

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 method according to an embodiment of the present invention as described above, in the uplink SC-FDM communication system, when transmitting a control signal without data, while ensuring the maximum number of available sequences, deterioration of sequence specific characteristics You can send and receive signals without

That is, in order to enable multi-cell operation, it is necessary to provide as many sequences as possible. For this purpose, a channel having a small length, particularly a control channel, is generated and a signal is transmitted and received using the sequence itself generated with a small length. present.

Claims (7)

In the terminal transmits a control signal in the uplink in the communication system, Subcarriers in a certain number of resource blocks (RBs) allocated at either or both ends of the system band to a predetermined number of control channels, each control channel comprising a prime number of subcarriers. Division; And Transmitting a signal through one control channel of the predetermined number of control channels, Each of the predetermined number of resource blocks includes 12 subcarriers, The control signal is represented by a Zadoff-Chu (ZC) sequence having a length corresponding to the number of subcarriers in the one control channel through which the control signal is transmitted. The predetermined number of resource blocks are divided into two control channels (hereinafter referred to as control channel A and control channel B), and the control channel when the predetermined number of resource blocks is one resource block allocated to one end of the system band. The number N _A of subcarriers of _A and the number N _B of subcarriers of the control channel B are (N _A , N _B ) = (1, 11), (5, 7), (7, 5) or (11, 1), and if the predetermined number of resource blocks are two resource blocks allocated one at each end of the system band or two resource blocks allocated at one end of the system band, the sub-channel of the control channel A The number N _A of carriers and the number N _B of subcarriers of the control channel B are (N _A , N _B ) = (1, 23), (5, 19), (7, 17), (11, 13), Corresponds to one of (13, 11), (17, 7), (19, 5), (23, 1), / RTI > The method of claim 1, The predetermined number of resource blocks are two resource blocks allocated at one end of the system band, and the control channel A and the control channel B are distributed at both ends of the system bandwidth, / RTI > 3. The method according to claim 1 or 2, The communication system is a SC-FDM (Single Carrier-Frequency Divisional Multiplexing) communication system, / RTI > delete delete delete delete

Images