CN101534285B - A sending method for reference signals - Google Patents

Abstract

The invention discloses a sending method for reference signals, which comprises the steps of determining different time frequency resources for target cells in the resource block pair of a subframe and sending the reference signal of the target cell corresponding to the time frequency resource in the time frequency resource of the subframe. The sending method of the invention is a method for sending reference signals in the target cells, which ensures that the time frequency positions for sending the positioning reference signals are different in the target cells, thereby reducing the interference among cells, ensuring the accurate positioning of the terminal, and improving the integral performance of the system.

Description

Reference signal sending method

Technical Field

The present invention relates to the field of mobile communication, and in particular, to a method for transmitting a reference signal.

Background

Orthogonal Frequency Division Multiplexing (OFDM) technology is essentially a multi-carrier modulation communication technology, which is one of the core technologies in fourth generation mobile communication. In order to overcome the fading, the channel is divided into a plurality of sub-channels in the frequency domain, the frequency spectrum characteristic of each sub-channel is approximately flat, and the sub-channels in the OFDM system are orthogonal to each other, thereby allowing the frequency spectrums of the sub-channels to overlap with each other, and thus, the frequency spectrum resources can be utilized to a large extent.

The Long Term Evolution (LTE) system is an important project for the third generation partnership. One subframe in an LTE system comprises two time slots, when the system adopts a conventional cyclic prefix, one time slot comprises uplink/downlink OFDM symbols with the length of 7, and when the system adopts an extended cyclic prefix, one time slot comprises uplink/downlink OFDM symbols with the length of 6. In the LTE system, one Resource Element (RE) is one subcarrier in one OFDM symbol, and one downlink Resource Block (RB) is composed of OFDM symbols (7 for a normal cyclic prefix and 6 for an extended cyclic prefix) which are formed by 12 consecutive subcarriers and a plurality of consecutive OFDM symbols, and has a frequency domain of 180kHz and a time domain of a time length of a general slot. The LTE system performs resource allocation with a resource block as a basic unit. As shown in fig. 1, in the frame structure diagram of the LTE system with a system bandwidth of 5MHz, a rectangle filled with a ruled line indicates one resource unit, rectangles with the same size in other blank spaces as the rectangle filled with the ruled line also indicate the resource unit, an area surrounded by a black thick solid line indicates one resource block, and each resource block includes 12 × 7 resource units.

The LTE system supports Multiple-Input Multiple-Output (MIMO) application of 4 antennas, and the corresponding antenna port #1, antenna port #2, antenna port #3, and antenna port #4 use a full-bandwidth Cell-specific reference signal (CRS) mode, and the Cell-specific reference signal function includes downlink channel quality measurement and downlink channel estimation (demodulation). The transmission positions of the common reference signals in the physical resource block are shown in fig. 2-a when the cyclic prefix is a normal cyclic prefix in the system, and are shown in fig. 2-b when the cyclic prefix is an extended cyclic prefix. Wherein T1, T2, T3 and T4 respectively correspond to the transmission positions of the common reference signals of the antenna ports 1 to 4. In addition, there is also a user-specific reference signal (UE-specific reference signals) that is transmitted only at the time-frequency domain position where the Physical Downlink Shared Channel (PDSCH) specific to the user is located. (the physical downlink control channel occupies the first n OFDM symbols in the subframe, and the physical shared channel occupies the remaining OFDM symbols in the subframe).

The base station needs to measure the position of a terminal (UE) in a cell, so that the terminal can be effectively configured and scheduled, at present, the terminal is measured by adopting a cell public reference signal (CRS signal), and due to the limitation of the sending mode of the existing CRS signal, the terminal is inaccurately positioned, the transmission performance of the whole system is influenced, and the overall performance of the system is reduced. The existing CRS signal transmission mode has the following defects:

(1) the transmission position of the CRS signal is fixed, the transmission positions in each frame (including each subframe) are the same, and the cross correlation is poor;

(2) the interference between adjacent cells is large; for example, for two-antenna transmission, the maximum multiplexing factor is 3;

(3) the emission power of the CRS signal is fixed, the emission power can not be flexibly changed, and the positioning performance is limited.

Due to the problems, the existing scheme causes inaccurate positioning of the terminal, affects the transmission performance of the whole system and causes the overall performance of the system to be reduced;

disclosure of Invention

The technical problem to be solved by the present invention is to provide a method for sending a reference signal, which reduces the interference between cells when positioning a terminal.

In order to solve the above problem, the present invention provides a method for transmitting a reference signal, including: determining different time-frequency resources for a target cell in a resource block pair of a subframe; and transmitting the reference signal of the target cell corresponding to the time-frequency resource on the time-frequency resource of the subframe.

Further, the method also has the following characteristics:

when n orthogonal frequency division multiplexing symbols used for sending the reference signal in a resource block pair of the subframe are n, wherein n is an integer greater than 0, and only one subcarrier on each orthogonal frequency division multiplexing symbol used for sending the reference signal is used for sending the reference signal, determining the positions of the subcarriers used for sending the reference signal on the n orthogonal frequency division multiplexing symbols by adopting the following method: a represents an N array, A being composed of N elements, i.e. a₀To a_N-1Wherein N elements contained in A are different from each other, a_iThe value of an element of a j row in an ith column in the NxN array is 1, and the value of elements at the rest positions of the ith column is 0; wherein i is 0,1,2, …, N-1, j is 1,2, …, N is a positive integer, preferably any value between 1 and 12, and the number of non-0 values overlapped by the array a obtained by cyclically shifting the array a on the rows or columns and the original array a is not more than 2; n elements of the array A are selected to be in one-to-one correspondence with the N orthogonal frequency division multiplexing symbols, and the value of each element in the N elements represents the position of a subcarrier on the orthogonal frequency division multiplexing symbol corresponding to the element.

Further, the method also has the following characteristics:

when n orthogonal frequency division multiplexing symbols used for sending the reference signal in a resource block pair of the subframe, n is an integer greater than 0, and d subcarriers on each orthogonal frequency division multiplexing symbol used for sending the reference signal are used for sending the reference signal, d is 2, 3, 4, 6 or 12, and the positions of the subcarriers used for sending the reference signal on the n orthogonal frequency division multiplexing symbols are determined by adopting the following method: a represents an N array, A being composed of N elements, i.e. a₀To a_N-1Wherein N elements contained in A are different from each other, a_iThe value of an element of a j row in an ith column in the NxN array is 1, and the value of elements at the rest positions of the ith column is 0;wherein i is 0,1,2, …, N-1, j is 1,2, …, N is a positive integer, preferably any value between 1 and 12, and the number of non-0 values overlapped by the array a obtained by cyclically shifting the array a on the rows or columns and the original array a is not more than 2; n elements are selected from the N elements of the array A and correspond to the N orthogonal frequency division multiplexing symbols one by one, the value of any element in the N elements represents the position of a subcarrier on the orthogonal frequency division multiplexing symbol corresponding to the element, and the number of subcarriers at intervals between the positions of d subcarriers on the same orthogonal frequency division multiplexing symbol is the same.

Further, the method also has the following characteristics:

when n orthogonal frequency division multiplexing symbols used for sending the reference signal in a resource block pair of the subframe are n, wherein n is an integer greater than 0, and d subcarriers on each orthogonal frequency division multiplexing symbol used for sending the reference signal are used for sending the reference signal, and d is an integer greater than 1, the positions of the subcarriers used for sending the reference signal on the n orthogonal frequency division multiplexing symbols are determined by adopting the following method: a represents an N array, A being composed of N elements, i.e. a₀To a_N-1Wherein N elements contained in A are different from each other, a_iThe value of an element of a j row in an ith column in the NxN array is 1, and the value of elements at the rest positions of the ith column is 0; wherein i is 0,1,2, …, N-1, j is 1,2, …, N is a positive integer, preferably any value between 1 and 12, and the number of non-0 values overlapped by the array a obtained by cyclically shifting the array a on the rows or columns and the original array a is not more than 2; and d groups are selected from the N elements of the array A, each group comprises N elements, the element composition of each group is different, the N elements in each group correspond to the N orthogonal frequency division multiplexing symbols one by one, and the value of each element in the N elements in each group represents the position of the subcarrier on the orthogonal frequency division multiplexing symbol corresponding to the element.

Further, the method also has the following characteristics:

n orthogonal frequency division multiplexing symbols for transmitting the reference signal in the resource block pair of the subframe, wherein n is a whole number larger than 0When there are d sub-carriers on each OFDM symbol for transmitting the reference signal, the position of the jth sub-carrier on the kth OFDM symbol is the kth sub-carrierA subcarrier; wherein,or, $N_{\mathrm{ID}}^{\mathrm{cell}}$ for a cell identity, M is the number of orthogonal frequency division multiplexing symbols available in a resource block pair of a subframe for transmitting the reference signal; mod is a modulo operation, P is an integer, j is a positive integer greater than 0 and less than or equal to d, and k is a positive integer greater than 0 and less than or equal to n.

Further, the method also has the following characteristics:

the number of orthogonal frequency division multiplexing symbols which can be used for sending the reference signal in the resource block pair of the subframe is M, n orthogonal frequency division multiplexing symbols which can be used for sending the reference signal are determined in the resource block pair of the subframe, n is an integer which is greater than 0, and n orthogonal frequency division multiplexing symbols which are actually used for sending the reference signal are selected from the M orthogonal frequency division multiplexing symbols which can be used for sending the reference signal by adopting the following method:or,wherein, $X=N_{\mathrm{ID}}^{\mathrm{cell}},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{PRBIndex},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{SubframeIndex},$ or, $X=$ $N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{SubframeIndex}+\mathrm{PRBIndex};$ PRBIndex is the index of the physical resource block for transmitting the reference signal, and subframe index is the index of the subframe for transmitting the reference signal;identifying the cell; the n OFDM symbols are the second of the M OFDM symbols available for transmitting the reference signalTo 1 byOrthogonal frequency division multiplexing symbols.

Further, the method also has the following characteristics:

for a multicast broadcast single frequency network subframe, an orthogonal frequency division multiplexing symbol in a resource block pair of the subframe, which can be used for sending the reference signal, is a remaining orthogonal frequency division multiplexing symbol in the resource block pair except for the first two orthogonal frequency division multiplexing symbols; for a subframe with a conventional cyclic prefix or a non-multicast broadcast single frequency network subframe with an extended cyclic prefix, the orthogonal frequency division multiplexing symbol which can be used for sending the reference signal in a resource block pair of the subframe is the remaining orthogonal frequency division multiplexing symbol after the orthogonal frequency division multiplexing symbol occupied by the physical downlink control channel and the orthogonal frequency division multiplexing symbol occupied by the common pilot frequency are removed in the resource block pair.

Further, the method also has the following characteristics:

the OFDM symbols capable of being used for sending the reference signal in the resource block pair of the multicast broadcast single frequency network subframe refer to the remaining OFDM symbols after the first two OFDM symbols in the resource block pair are removed; or, a half part of the remaining ofdm symbols; or, the remaining ofdm symbols belong to the ofdm symbols in the same timeslot; or, two orthogonal frequency division multiplexing symbols of the remaining orthogonal frequency division multiplexing symbols; or, three orthogonal frequency division multiplexing symbols of the remaining orthogonal frequency division multiplexing symbols; the ofdm symbol that can be used to transmit the reference signal is a remaining ofdm symbol after removing the ofdm symbol occupied by the physical downlink control channel and the ofdm symbol occupied by the common pilot in the subframe, in a resource block pair using the normal cyclic prefix subframe or a resource block pair using the extended cyclic prefix subframe; or, a half part of the remaining ofdm symbols; or, the remaining ofdm symbols belong to the ofdm symbols in the same timeslot; or, two orthogonal frequency division multiplexing symbols of the remaining orthogonal frequency division multiplexing symbols; or, three orthogonal frequency division multiplexing symbols of the remaining orthogonal frequency division multiplexing symbols.

Further, the method also has the following characteristics:

different columns in the array A correspond to different orthogonal frequency division multiplexing symbols in a time domain, different rows correspond to different subcarriers in a frequency domain, the array A is shifted by h rows according to the rows and h columns according to the columns respectively, and then elements corresponding to the n orthogonal frequency division multiplexing symbols one by one are selected from the shifted array A;

determining a pattern of reference signals for a cell due to the identity of the cell beingThe corresponding N × N array B ═ B for this cell₀，b₁，b₂，…，b_N-1]Obtained according to the following way:

h ═ X mod L, p ═ floor (X/M); or p ═ X mod L, h ═ floor (X/M),

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

or p ═ X mod M, h ═ floor (X/L), or, h ═ X mod M, p ═ floor (X/L),

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

mod represents the modulus; floor is a floor function, M is a positive integer, preferably taking the value N, L is a positive integer, preferably taking the value N or N, X is a positive integer and is determined by one or more of the following parameters: a cell identifier, a physical resource block index for transmitting the reference signal, and a subframe index for transmitting the reference signal.

The reference signal sending method of the invention specially defines the reference signal for terminal positioning, and provides the method for sending the reference signal in each cell, so that the time frequency positions for sending the positioning reference signal in the target cell are different, thereby reducing the inter-cell interference, ensuring the positioning precision of the terminal and improving the overall performance of the system.

Drawings

FIG. 1 is a frame structure diagram of an LTE system with a system bandwidth of 5 MHz;

fig. 2-a is a schematic diagram of a position of a reference signal common to cells transmitted by four antenna ports in a physical resource block when an LTE system employs a conventional cyclic prefix;

fig. 2-b is a schematic diagram of a position of a reference signal common to cells transmitted by four antenna ports in a physical resource block when an extended cyclic prefix is adopted in an LTE system;

fig. 3 is a flowchart of a reference signal transmission method;

FIG. 4 is a schematic diagram of array A in one embodiment;

FIG. 5 is a schematic diagram of array B in accordance with one embodiment;

fig. 6 is a schematic diagram of a location of a reference signal in a resource block in the first embodiment of the present invention;

fig. 7 is a schematic diagram of a location of a reference signal in a resource block in the second embodiment of the present invention;

fig. 8 is a schematic diagram of a location of a reference signal in a resource block in the first embodiment of the second embodiment;

fig. 9 is a schematic diagram of a location of a reference signal in a resource block in the second embodiment;

fig. 10 is a schematic diagram of a position of a reference signal in a resource block in the first embodiment of the third embodiment;

fig. 11 is a schematic position diagram of a reference signal in a resource block in the second embodiment in the third embodiment;

fig. 12 is a schematic diagram of a position of a reference signal in a resource block in the first embodiment in the fourth embodiment;

fig. 13 is a schematic diagram of a position of a reference signal in a resource block in the first embodiment in the fifth embodiment;

fig. 14 is a schematic diagram of a location of a reference signal in a resource block in the first embodiment in the sixth embodiment.

Detailed Description

For further explanation of the present invention, some specific embodiments of the reference signal transmission method according to the present invention are described below with reference to the drawings.

As shown in fig. 3, the reference signal transmitting method includes the steps of:

step 301, determining time-frequency resources for a target cell in a resource block pair of a subframe;

step 302, sending the reference signal of the cell corresponding to the time-frequency resource on the time-frequency resource of the subframe, and ending.

The sequence of the reference signal is generated by a ZC (Zadoff-Chu) sequence or a pseudo-random sequence or a wash sequence or a Gold sequence or an m-sequence.

The OFDM symbols available for transmitting reference signals in a resource block pair of one subframe are:

(1) for a Multicast Broadcast Single frequency network subframe (MBSFN for short), OFDM symbols which can be used for transmitting a reference signal need to be OFDM symbols remaining after removing the first two OFDM symbols in a resource block pair;

(2) for a subframe with a conventional cyclic prefix or a non-MBSFN subframe with an extended cyclic prefix, an OFDM symbol which can be used for transmitting a reference signal needs to be an OFDM symbol which is left in a resource block pair after an OFDM symbol occupied by a physical downlink control channel and an OFDM symbol occupied by a common pilot are removed.

Wherein a resource block pair index used for transmitting the reference signal is configured by a base station.

The following provides a method for selecting n OFDM symbols among OFDM symbols available for transmitting reference signals within a resource block pair of one subframe for transmitting reference signals:

the number of OFDM symbols which can be used for sending reference signals in the resource block pair of the subframe is M, and the cell identification isThen the process of the first step is carried out,

or,

wherein, $X=N_{\mathrm{ID}}^{\mathrm{cell}},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{PRBIndex},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}$ $+\mathrm{SubframeIndex},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{SubframeIndex}+\mathrm{PRBIndex};$ wherein PRBIndex is an index of a physical resource block for transmitting the reference signal, subframe index is an index of a subframe for transmitting the reference signal,is shown facing downwardsAnd (5) taking an integer.

The n OFDM symbols for transmitting the reference signal are the M OFDM symbols which can be used for transmitting the reference signal in the subframe1,2…, the firstOne OFDM symbol.

In the present invention, there are many methods for selecting n OFDM symbols from available OFDM symbols within a resource block pair of one subframe, and the method is not limited to the above one, and other methods for determining n OFDM symbols from available OFDM symbols are provided in the following first to sixth embodiments.

When n OFDM symbols used for transmitting a reference signal in a resource block pair of a subframe are determined, where n is an integer greater than 0, and each OFDM symbol used for transmitting the reference signal needs to occupy d subcarriers for transmitting the reference signal, where the subcarriers are subcarriers in the resource block pair used for transmitting the reference signal and are numbered 0,1, …, 11; various methods for determining the subcarriers are also provided in embodiments one to six described below.

The first embodiment is as follows:

in the first embodiment, in the time domain direction, the OFDM symbols used for transmitting the reference signal in the resource block pair of the subframe are all OFDM symbols except the OFDM symbol occupied by transmitting the physical downlink control channel and the OFDM symbol occupied by transmitting the common pilot in the resource block pair; in the frequency domain direction, only one subcarrier is occupied on each OFDM symbol for transmitting the reference signal to transmit the reference signal.

The number (denoted by n) and location of OFDM symbols used for transmitting reference signals are specifically determined as follows:

(1) for MBSFN sub-frames, n takes the value of 10; the positions of the OFDM symbols for transmitting the reference signals are the rest OFDM symbols except the first two OFDM symbols (namely the first OFDM symbol and the second OFDM symbol) in one resource block pair;

(2) for a non-MBSFN subframe adopting a conventional cyclic prefix, setting the number of symbols for transmitting a physical downlink control channel as m; 1 or 2, when the antenna transmits, the value of n is 11-m; 3 or 4 antenna transmission, wherein n is 8 when m is 1, 8 when m is 2, and 7 when m is 3 or 4;

the position of the OFDM symbol used for transmitting the reference signal is the rest OFDM symbols except the OFDM symbol used for transmitting the physical downlink control channel and the OFDM symbol used for transmitting the public pilot frequency in one resource block pair.

(3) For a non-MBSFN subframe adopting an extended cyclic prefix, setting the number of symbols for transmitting a physical downlink control channel as m; 1 or 2 antenna transmission, wherein when m is 1,2 and 3, n is 9-m, and when m is 4, n is 5; 3 or 4 antenna transmission, where n is 6 when m is 1,2, and 5 when m is 3, 4.

The position of the OFDM symbol used for transmitting the reference signal is the rest OFDM symbols except the OFDM symbol used for transmitting the physical downlink control channel and the OFDM symbol used for transmitting the public pilot frequency in one resource block pair.

The position of the OFDM symbol for transmitting the reference signal in the resource block pair is determined, and the subcarrier occupied on each OFDM symbol is determined, that is, the pattern of the reference signal (i.e., the position of the time-frequency resource for transmitting the reference signal in one resource block pair) can be determined. After the position of the OFDM symbol is fixed, different patterns are selected for different cells, and signal interference among the cells can be reduced. There are many methods for selecting different patterns for reference signals for different cells, which are not listed here, and the following exemplary methods are used as examples for explanation:

let us say that a is a for a common N × N array, where a ═ a₀，a₁，a₂，…，a_N-1]A is represented by N elements, wherein the N elements contained in A are different from each other, a_iRepresenting the a-th column in the NxN array_iThe element value of the row is 1, and the values of the elements at the rest positions of the ith column are 0; a is_iRepresents a in the i column_iThe row element is 1, and the remaining position elements in the ith column are 0, wherein i is 0,1,2, …, N-1, a_i1,2, …, N. N is a positive integer, preferably any value between 1 and 12. The value of the array A should satisfy the following conditions: the number of the non-0 values of the array obtained by circularly shifting the array A on the rows or columns and the original array A is not more than 2.

Determining a pattern of reference signals for a cell due to the identity of the cell beingThe corresponding N × N array B ═ B for this cell₀，b₁，b₂，…，b_N-1]Obtained according to the following way:

h X mod L, p floor (X/M), or,

p＝X mod L，h＝floor(X/M)；

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1

or,

p ═ X mod M, h ═ floor (X/L), or,

h＝X mod M，p＝floor(X/L)；

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

wherein, floor is a floor function,

$X=N_{\mathrm{ID}}^{\mathrm{cell}},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{PRBIndex},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{SubframeIndex},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{SubframeIndex}+\mathrm{PRBIndex};$ wherein PRBIndex is an index of a physical resource block for transmitting the reference signal, and subframe index is an index of a subframe for transmitting the reference signal. M is a positive integer, preferably N, L is a positive integer, preferably N or N.

The shift of the array in the time domain and/or the frequency domain is realized from the array A to the array B, and the shift corresponds to different cells (adopting cell identification) based on the same array AAs a main parameter) to obtain a different array B.

Only one subcarrier per reference signal transmitted OFDM symbol is used for transmitting reference signal data, and the subcarrier position in the resource block pair at which the reference signal is transmitted may be generated by array B. The n columns of the array B are selected according to the number n of OFDM symbols for transmitting the reference signal in the subframe, and the selection mode is not limited in the present invention, and may be consecutive n columns (for example, the first n columns or the last n columns) or non-consecutive n columns in the array B. The n columns selected from the array B correspond to n OFDM symbols used for transmitting the reference signal in the resource block pair one by one, and the corresponding manner may be sequential correspondence in the direction of the time domain, or other manners, which is not limited in the present invention. Taking a mode of sequentially corresponding according to the direction of the time domain as an example, in n columns selected from the array B, the tth (t is an integer less than or equal to n) column corresponds to the tth symbol in n OFDM symbols for transmitting the reference signal in the time domain direction, the position of the row corresponding to the element with the median value of 1 in the tth column is the position of the subcarrier in the corresponding tth OFDM symbol, for example, the element with the value of 1 in the tth column in the matrix B is located in the jth row of the tth column, and the position of the subcarrier in the OFDM symbol for transmitting the reference signal corresponding to the tth column is the jth subcarrier.

In the above method, different "columns" in the array correspond to different OFDM symbols in the time domain, and different "rows" correspond to different subcarriers in the frequency domain. In other embodiments, the time-frequency direction is also defined as a row, and the frequency-domain direction is defined as a column, which does not affect the implementation of the method.

According to the method, the cell identification is used as a main parameter, the patterns of the reference signals of all the cells are different, the interference among all the cells is reduced, and the physical resource block index and the subframe index are used as reference parameters, so that the patterns of the reference signals of different resource block pairs or different subframes are different, and the cross correlation is increased. When multi-antenna transmission is carried out, compared with the prior art, the method increases the multiplexing factor and further reduces the interference among all cells. In addition, different transmitting powers can be adopted for different cells according to parameters such as cell identification, physical resource block index and subframe index, so that the transmitting power for transmitting the reference signal can be flexibly changed along with the system performance, the positioning requirement of the terminal is ensured, and the system performance is improved. Moreover, the method is realized by shifting the array in the time domain and/or the frequency domain based on only one reference array A, and the procedure is simple and easy to implement.

Specific application example 1:

as shown in FIG. 4, array A is [8, 9, 5,2, 3, 10, 12, 11, 7, 1, 6, 4]Cell identityIs 1, N is 12, M is 12, L is 12,

then the process of the first step is carried out,

$h=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}12=1,p=\mathrm{floor}(N_{\mathrm{ID}}^{\mathrm{cell}}/12)=0;$

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

as shown in fig. 5, array B is [9, 5,2, 3, 10, 12, 11, 7, 1, 6, 4, 8 ];

when a resource block pair for transmitting a reference signal corresponds to an MBSFN subframe, the value of n is 10, the first 10 rows in the array are intercepted, and the specific position of the corresponding reference signal is as shown in fig. 6;

specific application example 2:

let A be [1,3,7,4,5,2,10,9,12,8,6,11]Cell identityIs 1, N is 12, M is 12, L is 12, $X=N_{\mathrm{ID}}^{\mathrm{cell}};$

then it is determined that, $h=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}12=1,p=\mathrm{floor}(N_{\mathrm{ID}}^{\mathrm{cell}}/12)=0;$

then B ═ 3,7,4,5,2,10,9,12,8,6,11, 1;

when a resource block pair for transmitting a reference signal corresponds to an MBSFN subframe, the value of n is 10, the first 10 rows in the array are intercepted, and the specific position of the corresponding reference signal is as shown in fig. 7;

example two:

in the second embodiment, the position of the OFDM symbol for transmitting the reference signal in the time domain direction resource block pair is the same as that in the first embodiment, but in the frequency domain direction, two subcarriers are required to transmit the reference signal on each OFDM symbol for transmitting the reference signal.

The same way as the reference signal pattern is determined in the first embodiment. After the array B is obtained, selecting N rows of the array B according to the number N of OFDM symbols for transmitting the reference signal in the subframe, wherein the N rows of the array B correspond to N OFDM symbols for transmitting the reference signal one by one, because two subcarriers are needed to transmit the reference signal on each OFDM symbol for transmitting the reference signal in the frequency domain direction, N elements are selected from the N elements of the array A to correspond to the N orthogonal frequency division multiplexing symbols one by one, the value of any element in the N elements represents the position of one subcarrier on the orthogonal frequency division multiplexing symbol corresponding to the element, and the number of subcarriers spaced between the positions of the two subcarriers on the same orthogonal frequency division multiplexing symbol is the same. For example, an element of the matrix B, which is located in the t-th column and has a value of 1, corresponds to the j-th subcarrier, positions of subcarriers in the OFDM symbol for transmitting the reference signal corresponding to the t-th column are the j-th subcarrier and the j + R-th subcarrier, a value of R is any one of values from 1 to 11, and preferably, a value of R is 6, so that positions of two subcarriers are uniformly distributed in 12 subcarriers in the frequency domain. The method is applicable to the case of selecting d subcarriers on each OFDM symbol, and the value of d may be not only 2, but also any value of 1 to 12 divisible by 12, such as 3, 4, 6, and 12.

Specific application example 1:

array A is [1,3,7,4,5,2,10,9,12,8,6,11]Cell identityIs 1, N is 12, M is 12, L is 12,

then $h=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}12=1,p=\mathrm{floor}(N_{\mathrm{ID}}^{\mathrm{cell}}/12)=0;$

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

Then B ═ 3,7,4,5,2,10,9,12,8,6,11, 1;

for a subframe adopting a conventional cyclic prefix, when 2-antenna transmission is performed and the number of symbols for transmitting a physical downlink control channel is 3, the number of OFDM symbols for transmitting the reference signal is 8, the first 8 columns of the array B are intercepted, the position of each group of subcarriers is determined, the positions of the second group of subcarriers are respectively added with 6 on the basis of the positions of the subcarriers in the first group, and the specific positions of the corresponding reference signals are shown in fig. 8.

Specific application example 2:

array A is [8, 9, 5,2, 3, 10, 12, 11, 7, 1, 6, 4 ]]Cell identityIs 1, N is 12, M is 12, L is 12,

then $h=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}12=1,p=\mathrm{floor}(N_{\mathrm{ID}}^{\mathrm{cell}}/12)=0;$

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

Then B ═ 9, 5,2, 3, 10, 12, 11, 7, 1, 6, 4, 8;

for a subframe adopting a conventional cyclic prefix, when 2-antenna transmission is performed and the number of symbols for transmitting a physical downlink control channel is 3, the number of OFDM symbols for transmitting the reference signal is 8, the first 8 columns of the array B are intercepted, the position of each group of subcarriers is determined, the positions of the second group of subcarriers are respectively added with 6 on the basis of the positions of the subcarriers in the first group, and the specific positions of the corresponding reference signals are shown in fig. 9.

Example three:

the third embodiment has the same requirements for the number and position of OFDM symbols used in the time domain for transmission and the number of subcarriers occupied by each OFDM symbol in the frequency domain as the second embodiment, and is different from the second embodiment in that the method for determining the position of the subcarrier used for transmission of the reference signal on each OFDM symbol is different according to the obtained array B.

In the third embodiment, after obtaining the array B, two different sets of n column values are selected in the array B according to the number n of the OFDM symbols for transmitting the reference signal in the subframe, and are used for determining the positions of two subcarriers on the n OFDM symbols for transmitting the reference signal, corresponding to the n OFDM symbols for transmitting the reference signal, and the method for determining the subcarriers is the same as that in the second embodiment. The selection method may be to select the array B as the first n columns and the last n columns, or the first n columns and the middle n rows, or the first 2 × n columns, etc., which is not limited by the invention.

In other embodiments, when the number of subcarriers occupied by each OFDM symbol is d, and d is an integer greater than 1, d groups are selected from N elements of the array a, each group includes N elements, the elements of each group are different in composition, N elements in each group correspond to the N orthogonal frequency division multiplexing symbols one to one, and a value of each element in N elements in each group indicates a position of a subcarrier on the orthogonal frequency division multiplexing symbol corresponding to the element.

Specific application example 1:

a is [1,3,7,4,5,2,10,9,12,8,6,11 ]]Cell identityIs 1, N is 12, M is 12, L is 12, $X=N_{\mathrm{ID}}^{\mathrm{cell}},$

then $h=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}12,p=\mathrm{floor}(N_{\mathrm{ID}}^{\mathrm{cell}}/12);$

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

B＝[3,7,4,5,2,10,9,12,8,6,11,1]；

For a subframe using an extended cyclic prefix, when 2-antenna transmission is performed and the number of symbols for transmitting a physical downlink control channel is 3, the number of OFDM symbols for transmitting the reference signal is 6, the first 6 columns and the last 6 columns in the array B are truncated, and the specific positions of the corresponding reference signals are shown in fig. 10.

Specific application example 2:

a is [8, 9, 5,2, 3, 10, 12, 11, 7, 1, 6, 4 ]]Cell identityIs 1, N is 12, M is 12, L is 12,

then $h=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}12,p=\mathrm{floor}(N_{\mathrm{ID}}^{\mathrm{cell}}/12);$

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

Then B ═ 9, 5,2, 3, 10, 12, 11, 7, 1, 6, 4, 8;

for a subframe using an extended cyclic prefix, when 2-antenna transmission is performed and the number of symbols for transmitting a physical downlink control channel is 3, the number of OFDM symbols for transmitting the reference signal is 6, the first 6 columns and the last 6 columns in the array are truncated, and the specific positions of the corresponding reference signals are shown in fig. 11.

Example four:

in the fourth embodiment, in the frequency domain direction, two subcarriers are occupied on each OFDM symbol for transmitting reference signals to transmit reference signals.

The position of the OFDM symbol used for transmitting the reference signal is specifically determined as follows:

(1) for the MBSFN subframe, the OFDM symbols available in the resource block pair are the remaining OFDM symbols after the first two OFDM symbols are removed, or the half part of the remaining OFDM symbols; or, the remaining OFDM symbols are orthogonal frequency division multiplexing symbols belonging to the same time slot (time slot 1 or time slot 2);

(2) for a subframe with a conventional cyclic prefix or a non-MBSFN subframe with an extended cyclic prefix, an available OFDM symbol in a resource block pair is an OFDM symbol left after an OFDM symbol occupied by a physical downlink control channel and an OFDM symbol occupied by a common pilot frequency are removed, or the part of one half of the remaining OFDM symbol is removed; or, the remaining OFDM symbols may belong to OFDM symbols in one slot (slot 1 or slot 2).

When S is 0, the OFDM symbol for transmitting the reference signal is the first half OFDM symbol of the available OFDM symbols in the subframe, and when S is 1, the OFDM symbol for transmitting the reference signal is the second half OFDM symbol of the available OFDM symbols in the subframe; or, when S is 0, the OFDM symbol indicating the transmission of the reference signal is an available OFDM symbol belonging to the first slot in the remaining OFDM symbols in the resource block pair, and when S is 1, the OFDM symbol indicating the transmission of the reference signal is an available OFDM symbol belonging to the second slot in the resource block pair.

Referring to the first embodiment, when determining array B from array a,

h ═ X mod L, p ═ floor (X/M), or, p ═ X mod L, h ═ floor (X/M);

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

or

p ═ X mod M, h ═ floor (X/L), or, h ═ X mod M, p ═ floor (X/L);

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

wherein,or,or, or,

in the fourth embodiment, after the array B is obtained, the number n of OFDM symbols used for transmitting the reference signal in the resource block is determined, n columns of the array B are selected to be in one-to-one correspondence with the n OFDM symbols used for transmitting the reference signal, and since two subcarriers are required to transmit the reference signal on each OFDM symbol used for transmitting the reference signal in the frequency domain direction, the positions of two subcarriers in the OFDM symbol used for transmitting the reference signal corresponding to the subcarrier are determined according to the position of the element whose median in each column is 1 in the n columns selected from the array B. For example, an element of the matrix B, which is located in the t-th column and has a value of 1, corresponds to the j-th subcarrier, positions of subcarriers in the OFDM symbol for transmitting the reference signal corresponding to the t-th column are the j-th subcarrier and the j + R-th subcarrier, a value of R is any one of values from 1 to 11, and preferably, a value of R is 6, so that positions of two subcarriers are uniformly distributed in 12 subcarriers in the frequency domain.

Specific application example 1:

a is [8, 9, 5,2, 3, 10, 12, 11, 7, 1, 6, 4 ]]Cell identityIs 2, N is 12, M is 12, L is 12,

then h X mod12 1, p floor (X/12) 0;

b_i＝(a_(i+h)modM+p)modM,i＝0,1,2,…,N-1；

B＝[9，5，2，3，10，12，11，7，1，6，4，8]；

$S=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}2=2\mathrm{mod}2=0$

for the MBSFN subframe, the number of OFDM symbols for transmitting the reference signal is 5, the first 5 columns and the last 5 columns in the array are truncated, because S is 0, the OFDM symbol for transmitting the reference signal is determined to be the first half of the available OFDM symbols in the subframe, that is, located on the 3 rd to 7 th OFDM symbols in the MBSFN subframe, and the specific position of the corresponding reference signal is as shown in fig. 12.

Different from the methods in the first to fourth embodiments, embodiments five and sixth provide a method for selecting subcarriers, that is, when n OFDM symbols for transmitting reference signals in resource block pairs of a subframe are determined, n is an integer greater than 0, and d subcarriers are used for transmitting reference signals on each OFDM symbol for transmitting reference signals, the position of the jth subcarrier on the kth OFDM symbol may be:

wherein,or,

wherein,for cell identification, M is the number of OFDM symbols available in a resource block pair of a subframe for transmitting the reference signal; mod is a modulo operation, P is an integer, j is a positive integer greater than 0 and less than or equal to d, and k is a positive integer greater than 0 and less than or equal to n. With this determination method, the d subcarriers on each OFDM symbol are uniformly distributed in the frequency domain, and the following further describes embodiment five and embodiment six.

Example five:

in the fifth embodiment, in the time domain direction, the OFDM symbols used for transmitting the reference signal in the resource block are two OFDM symbols excluding the OFDM symbol occupied by transmitting the physical downlink control channel and the OFDM symbol occupied by transmitting the common pilot in the resource block. In the frequency domain direction, reference signals are transmitted by occupying three subcarriers on each OFDM symbol for transmitting reference signals.

The positions of two OFDM symbols used for transmitting the reference signal are determined as follows:

(1) for the MBSFN subframe, the OFDM symbol for sending the reference signal is two OFDM symbols in the rest OFDM symbols except the first two OFDM symbols in the subframe;

(2) for a subframe with a conventional cyclic prefix or a non-MBSFN subframe with an extended cyclic prefix, the OFDM symbol for sending the reference signal is two OFDM symbols in the rest OFDM symbols after the symbol occupied by the physical downlink control channel and the symbol occupied by the common pilot frequency are removed from the subframe.

Two OFDM symbols are selected from available OFDM symbols, and many methods are available, and the following method is used as an example for illustration, but the present invention is not limited thereto:

cell identification ofThe number of OFDM symbols available for transmitting the reference signal in the subframe is M, then,

the OFDM symbol for transmitting the reference signal is the second OFDM symbol which can be used for transmitting the reference signal in the subframeIs first and secondA number of OFDM symbols;

there are many methods available for selecting three subcarriers in two OFDM symbols, and the following method is used as an example, but the present invention is not limited thereto:

cell identification of

The reference signal is located on a subcarrier (P + k × 2) mod12, a subcarrier (P + k × 2+4) mod12, and a subcarrier (P + k × 2+8) mod12 of a kth OFDM symbol of OFDM symbols in which the reference signal is transmitted, wherein k is 0, 1;

specific application example 1:

for an MBSFN subframe, the cell identification is 2, the number of OFDM symbols available to transmit the reference signal in the subframe is 10, then,

for the MBSFN sub-frame,then it is determined that the reference signal is transmitted on the 5 th and 6 th OFDM symbols in the 10 OFDM symbols (i.e. the 3 rd to 12 th OFDM symbols of the resource block pair) that can be used for transmitting the reference signal, and then the OFDM symbols for transmitting the reference signal are on the 1 st subcarrier, the 5 th subcarrier, the 9 th subcarrier and the 3 rd subcarrier, the 7 th subcarrier and the 11 th subcarrier of the 5 th OFDM symbol in the subframe, and the corresponding specific positions of the reference signal are as shown in fig. 13.

Example six:

in the sixth embodiment, as in the fifth embodiment, in the time domain direction, the OFDM symbols used for transmitting the reference signal in the resource block are two OFDM symbols excluding the OFDM symbol occupied by transmitting the physical downlink control channel and the OFDM symbol occupied by transmitting the common pilot in the resource block. In the frequency domain direction, six subcarriers are occupied on each OFDM symbol for transmitting reference signals to transmit the reference signals.

The method of determining the positions of two OFDM symbols transmitting the reference signal in the sixth embodiment is the same as that in the fifth embodiment.

There are many available methods for selecting six subcarriers in two OFDM symbols, and the following method is used as an example for illustration, but the present invention is not limited thereto:

cell identification ofThe number of OFDM symbols available for transmitting the reference signal in the subframe is M, then,

when six subcarriers are used for transmitting reference signal data on each OFDM symbol for transmitting the reference signal, the reference signal is located on a subcarrier (P + k) mod12, a subcarrier (P + k +2) mod12, a subcarrier (P + k +4) mod12, a subcarrier (P + k +6) mod12, a subcarrier (P + k +8) mod12 and a subcarrier (P + k +10) mod12 of a kth OFDM symbol in the OFDM symbols for transmitting the reference signal, wherein k is 0, 1;

specific application example 1:

for an MBSFN subframe, the cell identification is 2, the number of OFDM symbols available to transmit the reference signal in the subframe is 10, then,

for an MBSFN subframe, it is determined to transmit reference signals on the 5 th and 6 th OFDM symbols in 10 OFDM symbols (i.e. 3 to 12 OFDM symbols of a resource block pair) that can be used for transmitting reference signals, and further, transmit reference signals on the 1 st subcarrier, the 3 rd subcarrier, the 5 th subcarrier, the 7 th subcarrier, the 9 th subcarrier, the 11 th subcarrier and the 2 nd subcarrier, the 4 th subcarrier, the 6 th subcarrier, the 8 th subcarrier, the 10 th subcarrier and the 12 th subcarrier of the 5 th OFDM symbol in the subframe where the OFDM symbols for transmitting the reference signals are the OFDM symbols, where the corresponding specific positions of the reference signals are shown in fig. 14.

In the above embodiment, other preferred values of the matrix a are:

A＝[6 4 8 1 7 2 3 5 10 9]；A＝[5 4 10 6 9 3 1 11 2 7 8]；

A＝[1 4 6 10 8 7 3 9 2 11 5 12]；A＝[8 9 5 2 3 10 12 11 7 1 6 4]

in the method, the reference signal for positioning the terminal can be constructed and sent on the time frequency resource arranged in the resource block, different time frequency resources are adopted for adjacent cells, the interference between adjacent regions is reduced, and the method is favorable for improving the positioning accuracy of the terminal.

In the time domain, the method for selecting the OFDM symbol used for transmitting the reference signal is only a preferred method in the above embodiment, and one or more OFDM symbols may be optionally selected from the OFDM symbols usable for transmitting the reference signal in the subframe for transmitting the reference signal. Similarly, when determining the number and position of the subcarriers occupied by each OFDM symbol after determining the OFDM symbol used for transmitting the reference signal, one or more subcarriers may be selected from 12 subcarriers corresponding to each OFDM symbol, the number of the subcarriers (represented by Q) may be any number from 1 to 12, and there are many methods for selecting Q subcarriers from 12 subcarriers corresponding to each OFDM symbol, which are not listed here, but the preferred method is similar to the method in the second embodiment, and the uniform distribution of the Q subcarriers on the 12 subcarriers is maintained as much as possible. In summary, the selection method for the OFDM symbol and the selection method for the subcarrier on the OFDM symbol in the above embodiments do not limit the present invention, as long as the patterns of the reference signals of the adjacent cells can be ensured to be different after the two selection processes.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (8)

1. A method for transmitting a reference signal, comprising:

determining different time-frequency resources for a target cell in a resource block pair of a subframe;

sending a reference signal of a target cell corresponding to the time-frequency resource on the time-frequency resource of the subframe;

the number of orthogonal frequency division multiplexing symbols which can be used for sending the reference signal in the resource block pair of the subframe is M, n orthogonal frequency division multiplexing symbols which can be used for sending the reference signal are determined in the resource block pair of the subframe, n is an integer which is greater than 0, and n orthogonal frequency division multiplexing symbols which are actually used for sending the reference signal are selected from the M orthogonal frequency division multiplexing symbols which can be used for sending the reference signal by adopting the following method:

wherein, $X=N_{\mathrm{ID}}^{\mathrm{cell}},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{PRBIndex},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}$ $+\mathrm{SubframeIndex},$ or, $X=N_{\mathrm{ID}}^{\mathrm{cell}}+\mathrm{SubframeIndex}+\mathrm{PRBIndex};$ PRBIndex is the index of the physical resource block for transmitting the reference signal, and subframe index is the index of the subframe for transmitting the reference signal;identifying the cell;

the n OFDM symbols are the second of the M OFDM symbols available for transmitting the reference signalTo 1 byOrthogonal frequency division multiplexing symbols.

2. The method of claim 1,

when n orthogonal frequency division multiplexing symbols used for sending the reference signal in a resource block pair of the subframe are n, wherein n is an integer greater than 0, and only one subcarrier on each orthogonal frequency division multiplexing symbol used for sending the reference signal is used for sending the reference signal, determining the positions of the subcarriers used for sending the reference signal on the n orthogonal frequency division multiplexing symbols by adopting the following method:

a represents an N array, A being composed of N elements, i.e. a₀To a_N-1Wherein N elements contained in A are different from each other, a_iThe value of an element of a j row in an ith column in the NxN array is 1, and the value of elements at the rest positions of the ith column is 0; wherein i is 0,1,2, …, N-1, j is 1,2, …, N is a positive integer and is any value between 1 and 12, and the number of non-0 values overlapped by the array a obtained by cyclically shifting rows or columns and the original array a is not more than 2;

n elements of the array A are selected to be in one-to-one correspondence with the N orthogonal frequency division multiplexing symbols, and the value of each element in the N elements represents the position of a subcarrier on the orthogonal frequency division multiplexing symbol corresponding to the element.

3. The method of claim 1,

when n orthogonal frequency division multiplexing symbols used for sending the reference signal in a resource block pair of the subframe, n is an integer greater than 0, and d subcarriers on each orthogonal frequency division multiplexing symbol used for sending the reference signal are used for sending the reference signal, d is 2, 3, 4, 6 or 12, and the positions of the subcarriers used for sending the reference signal on the n orthogonal frequency division multiplexing symbols are determined by adopting the following method:

a representsN by N array, A consisting of N elements, i.e. a₀To a_N-1Wherein N elements contained in A are different from each other, a_iThe value of an element of a j row in an ith column in the NxN array is 1, and the value of elements at the rest positions of the ith column is 0; wherein i is 0,1,2, …, N-1, j is 1,2, …, N is a positive integer and is any value between 1 and 12, and the number of non-0 values overlapped by the array a obtained by cyclically shifting rows or columns and the original array a is not more than 2;

n elements are selected from the N elements of the array A and correspond to the N orthogonal frequency division multiplexing symbols one by one, the value of any element in the N elements represents the position of a subcarrier on the orthogonal frequency division multiplexing symbol corresponding to the element, and the number of subcarriers at intervals between the positions of d subcarriers on the same orthogonal frequency division multiplexing symbol is the same.

4. The method of claim 1,

when n orthogonal frequency division multiplexing symbols used for sending the reference signal in a resource block pair of the subframe are n, wherein n is an integer greater than 0, and d subcarriers on each orthogonal frequency division multiplexing symbol used for sending the reference signal are used for sending the reference signal, and d is an integer greater than 1, the positions of the subcarriers used for sending the reference signal on the n orthogonal frequency division multiplexing symbols are determined by adopting the following method:

a represents an N array, A being composed of N elements, i.e. a₀To a_N-1Wherein N elements contained in A are different from each other, a_iThe value of an element of a j row in an ith column in the NxN array is 1, and the value of elements at the rest positions of the ith column is 0; wherein i is 0,1,2, …, N-1, j is 1,2, …, N is a positive integer and is any value between 1 and 12, and the number of non-0 values overlapped by the array a obtained by cyclically shifting rows or columns and the original array a is not more than 2;

and d groups are selected from the N elements of the array A, each group comprises N elements, the element composition of each group is different, the N elements in each group correspond to the N orthogonal frequency division multiplexing symbols one by one, and the value of each element in the N elements in each group represents the position of the subcarrier on the orthogonal frequency division multiplexing symbol corresponding to the element.

5. The method of claim 1,

when n orthogonal frequency division multiplexing symbols used for sending the reference signal in the resource block pair of the subframe are n, wherein n is an integer greater than 0, and d subcarriers are used for sending the reference signal on each orthogonal frequency division multiplexing symbol used for sending the reference signal, the position of the jth subcarrier on the kth orthogonal frequency division multiplexing symbol is respectively the kth subcarrierA subcarrier;

wherein,or,

for a cell identity, M is the number of orthogonal frequency division multiplexing symbols available in a resource block pair of a subframe for transmitting the reference signal; mod is a modulo operation, P is an integer, j is a positive integer greater than 0 and less than or equal to d, and k is a positive integer greater than 0 and less than or equal to n.

6. The method of claim 1,

for a multicast broadcast single frequency network subframe, an orthogonal frequency division multiplexing symbol in a resource block pair of the subframe, which can be used for sending the reference signal, is a remaining orthogonal frequency division multiplexing symbol in the resource block pair except for the first two orthogonal frequency division multiplexing symbols;

for a subframe with a conventional cyclic prefix or a non-multicast broadcast single frequency network subframe with an extended cyclic prefix, the orthogonal frequency division multiplexing symbol which can be used for sending the reference signal in a resource block pair of the subframe is the remaining orthogonal frequency division multiplexing symbol after the orthogonal frequency division multiplexing symbol occupied by the physical downlink control channel and the orthogonal frequency division multiplexing symbol occupied by the common pilot frequency are removed in the resource block pair.

7. The method of claim 1,2, 3, 4 or 5,

the OFDM symbols capable of being used for sending the reference signal in the resource block pair of the multicast broadcast single frequency network subframe refer to the remaining OFDM symbols after the first two OFDM symbols in the resource block pair are removed; or, a half part of the remaining ofdm symbols; or, the remaining ofdm symbols belong to the ofdm symbols in the same timeslot; or, two orthogonal frequency division multiplexing symbols of the remaining orthogonal frequency division multiplexing symbols; or, three orthogonal frequency division multiplexing symbols of the remaining orthogonal frequency division multiplexing symbols;

the ofdm symbol that can be used to transmit the reference signal is a remaining ofdm symbol after removing the ofdm symbol occupied by the physical downlink control channel and the ofdm symbol occupied by the common pilot in the subframe, in a resource block pair using the normal cyclic prefix subframe or a resource block pair using the extended cyclic prefix subframe; or, a half part of the remaining ofdm symbols; or, the remaining ofdm symbols belong to the ofdm symbols in the same timeslot; or, two orthogonal frequency division multiplexing symbols of the remaining orthogonal frequency division multiplexing symbols; or, three orthogonal frequency division multiplexing symbols of the remaining orthogonal frequency division multiplexing symbols.

8. The method of claim 2, 3 or 4,

different columns in the array a correspond to different orthogonal frequency division multiplexing symbols in a time domain, different rows correspond to different subcarriers in a frequency domain, the array a is shifted by h rows according to the rows and h columns according to the columns to obtain an array B, and then elements corresponding to the n orthogonal frequency division multiplexing symbols one to one are selected from the shifted array a, which specifically includes:

let N × N array B ═ B₀，b₁，b₂，…，b_N-1]Then, there are:

h ═ X mod L, p ═ floor (X/M); or p ═ X mod L, h ═ floor (X/M),

b_i＝(a_(i+h)modM+p)mod M,i＝0,1,2,…,N-1；

or p ═ X mod M, h ═ floor (X/L), or, h ═ X mod M, p ═ floor (X/L),

b_i＝(a_(i+h)modM+p)mod M,i＝0,1,2,…,N-1；

mod represents the modulus; floor is a floor function, M is a positive integer and takes on the value N, L is a positive integer and takes on the value N or N, X is a positive integer and is determined by one or more of the following parameters: a cell identifier, a physical resource block index for transmitting the reference signal, and a subframe index for transmitting the reference signal.