CN102142916B - Multiplexing method and multiplexing equipment of reference signal - Google Patents

Abstract

The embodiment of the invention discloses a reference signal multiplexing method and multiplexing equipment. By determining the number of subcarriers on the transmission frequency band; according to the number of subcarriers, determine the common root sequence carried by the root sequence of the reference signal, the number of bits of the common root sequence is the same as the number of subcarriers; according to the number of subcarriers of the first reference signal in the transmission At a preset predetermined position in the frequency band, the number of bits is intercepted from the common root sequence to form the root sequence of the first reference signal. Furthermore, when data transmission is performed on the same time-frequency resource, reference signals with not exactly the same root sequence are multiplexed.

Description

Reference signal multiplexing method and multiplexing equipment

technical field

The invention relates to the communication field, in particular to a multiplexing method and multiplexing equipment of reference signals.

Background technique

In the LTE (Long Term Evolution) or LTE-A (Long Term Evolution Advanced) standard in wireless communication, the uplink of the LTE system adopts the SC-FDMA (Single Carrier Frequency Division Multiple Access) access method. As shown in Figure 1, the period of the SC-FDMA symbol is the basic time unit of the slave time, and the duration of one SC-FDMA symbol is about 1/14 millisecond. Each SC-FDMA symbol is divided into multiple subcarriers in the frequency domain, and the interval between subcarriers is set to 15kHz in the LTE protocol. In the frequency domain, the basic unit is a subcarrier.

To sum up, time-frequency resources are divided into uniform units called Resource Elements (RE). Each RE occupies the duration of one SC-FDMA symbol in time and the width of one subcarrier in frequency. One symbol (for example, one QPSK/16QAM/64QAM symbol) can be transmitted on each RE. FIG. 2 is a schematic diagram of dividing wireless resources into resource units.

The information transmitted in the wireless communication system can be roughly divided into two types: data (data) and reference information (ReferenceSignal). The data is the information that the sending end needs to transmit to the receiving end. This information is originally unknown at the receiving end and needs to be obtained through demodulation; while the reference information is information that both the sending end and the receiving end already know. Its function is to It is convenient for the receiving end to perform operations such as channel estimation, thereby helping the receiving end to perform data demodulation.

From the perspective of each RE, if noise is not considered, the received signal will be the product of the transmitted signal and the channel response on this RE. At the same time, wireless channels have correlations in the time domain and frequency domain. In short, the channel responses on adjacent REs are similar, so as long as the reference signal is transmitted on some REs, the receiving end can get the information on this RE. channel estimation.

The above figure is taken as an example, assuming that RE5 is used to transmit reference signals, and other REs are used to transmit data signals. Suppose the reference signal data on RE5 is r ₅ , and the channel response on RE5 is H ₅ , then the signal received at the receiving end is y ₅ =H ₅ r ₅ (regardless of factors such as noise), since r ₅ is already know, so Then the channel estimation on RE5 is obtained. The channel response of the surrounding RE1-9 is very similar to that of RE5, and the channel estimation on the surrounding REs can be obtained through some algorithm processing, so that data demodulation can be performed.

In the prior art, some REs are used to transmit reference signals. Specifically, some SC-FDMA symbols will be used to transmit reference signals, and on these SC-FDMA symbols, reference signals will be sent on continuous subcarriers in the frequency band where channel estimation is required, as shown in Figure 2b As shown, all subcarriers of the 4th and 11th SC-FDM symbols are used to transmit reference signals. For example, the generation of the reference signal sequence adopts the following expression: s

${\mathrm{<span\; class="notranslate">\; r</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j\&alpha;n</span>}}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$

here It is called the root sequence, and the sequence length is the same as the number of subcarriers required to obtain channel estimation. For example, if channel estimation needs to be performed on 120 subcarriers, a root sequence with a length of 120 will be selected. Obviously, the length of the reference signal is also 120 bits. e ^jαn is called a cyclic shift (Cyclic Shift, CS), where the value of α is a value between [0,2π). The role of the cyclic shift is to multiplex multiple reference signals on the same time-frequency resource, which will be further described below.

As mentioned above, reference signals are used for channel estimation. In some scenarios, more than one reference signal can be transmitted on the same time-frequency resource, differentiated by cyclic shift, and an independent channel estimation value can be obtained at the receiving end. One possible scenario is multi-user MIMO technology (MU-MIMO). At this time, there are two users performing data transmission on the same time-frequency resource. At this time, the receiver needs to obtain independent channel estimates of the two users to perform demodulation respectively. In the LTE protocol, two users will send reference signals on the same RE and distinguish them by cyclic shift.

To achieve this, the reference signal needs to meet the following conditions:

1. Both reference signals use the same root sequence

2. The two reference signals use different cyclic shifts

The following example illustrates how the receiving end performs channel estimation on the two reference signals respectively.

Assuming reference signal 1, the sequence is That is, the sequence length is N, the cyclic shift α=0, and it is placed bit by bit on the 1st to N subcarriers for transmission, and the channel it passes through is expressed as H ₁ (n) (1≤n≤N); suppose Reference signal 2, the sequence is That is, the same root sequence is used, the sequence length is N, and the cyclic shift α=π is placed bit by bit on the 1st to N subcarriers for transmission. The channel it passes through is expressed as H ₂ (n)(1≤ n≤N). The signal obtained at the receiving end can be approximately expressed as the product of the reference signal and the channel response on each subcarrier, and since the two are sent on the same time-frequency resource, ignoring the noise, the received signal can be expressed as:

y(n)=r ₁ (n)H ₁ (n)+r ₂ (n)H ₂ (n)

For the received signal divided by the root sequence, we get:

$\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j\&pi;n</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$

The sequence z(n) is processed as follows:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

Since the wireless channel response is approximately equal on adjacent subcarriers, the above steps eliminate the channel response of user 2. the resulting sequence length is for Perform interpolation processing and re-expand into a sequence of length N to obtain a channel estimate of the channel response H ₁ (n) (1≤n≤N).

The sequence z(n) is processed as follows:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

This process eliminates User 1's channel response. the resulting sequence length is for Perform interpolation processing and re-expand into a sequence of length N to obtain a channel estimate of the channel response H ₂ (n) (1≤n≤N).

In the prior art, there may be more than two reference signals that can be multiplexed, and they can be distinguished one by one as long as they have the same root sequence and each reference signal has a different cyclic shift. However, if the root sequences of the two reference signals on the subcarriers transmitted together are not completely the same, for example, if the lengths of the root sequences are different, they cannot be distinguished.

Contents of the invention

Embodiments of the present invention provide a reference signal multiplexing method and multiplexing device, so that when the root sequences are not completely the same, the reference signals with not completely the same root sequence can be multiplexed during data transmission on the same time-frequency resource.

An embodiment of the present invention provides a method for multiplexing reference signals, including:

Determine the number of subcarriers on the transmission frequency band, the number of subcarriers refers to the number of subcarriers in the transmission frequency band, and the subcarriers are basic units in the frequency domain;

Determine the common root sequence carried by the reference signal root sequence according to the number of subcarriers, and the number of bits of the common root sequence is the same as the number of subcarriers;

The root sequence of the first reference signal is formed by truncating the number of bits from the common root sequence according to the predetermined predetermined position of the subcarrier of the first reference signal in the transmission frequency band.

The embodiment of the present invention also provides a reference signal multiplexing device, including a common root sequence generation module: used to determine the number of subcarriers on the transmission frequency band, and determine the common root sequence for the reference signal root sequence to be carried according to the number of subcarriers. The number of digits of the common root sequence is the same as the number of subcarriers, the number of subcarriers refers to the number of subcarriers in the transmission frequency band, and the subcarriers are the basic units in the frequency domain;

The first reference signal generation module: according to the predetermined position preset in the transmission frequency band of the subcarrier of the first reference signal, the number of bits is intercepted from the common root sequence to form the root sequence of the first reference signal.

Furthermore, according to the embodiment of the present invention, the common root sequence is determined according to the number of subcarriers, and the root sequence of the first reference signal is formed by truncating the number of bits from the common root sequence according to the predetermined positions of the subcarriers in the transmission frequency band. Furthermore, when data transmission is performed on the same time-frequency resource, reference signals with not exactly the same root sequence can be multiplexed.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is a schematic diagram of dividing each SC-FDMA symbol into multiple subcarriers in the frequency domain in the prior art;

FIG. 2a is a schematic diagram of dividing wireless resources into resource units in the prior art;

FIG. 2b is a schematic diagram of reference signals used by all subcarriers of the 4th and 11th SC-FDM symbols in the prior art;

3 is a flowchart of a method for multiplexing reference signals according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a common root sequence when subcarriers allocated to two reference signals overlap;

FIG. 5 is another schematic diagram of the common root sequence when the subcarriers corresponding to the two reference signals are overlapped;

FIG. 6 is a schematic diagram of a common root sequence when subcarriers allocated to three reference signals overlap;

FIG. 7 is a schematic structural diagram of a reference signal multiplexing device; and

FIG. 8 is a schematic structural diagram of another embodiment of a reference signal multiplexing device according to the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Please refer to FIG. 3, an embodiment of the present invention provides a method for multiplexing reference signals, including:

Step 301: Determine the number of subcarriers in the transmission frequency band; it can be understood that the transmission frequency band here can be divided into several subbands in the frequency domain, or can be understood as a larger transmission frequency band composed of several subbands.

Step 302: Determine the common root sequence carried by the reference signal root sequence according to the number of subcarriers, and the number of bits of the common root sequence is the same as the number of subcarriers;

Step 303: According to the predetermined positions preset in the transmission frequency band of the subcarriers of the first reference signal, the number of bits is truncated from the common root sequence to form the root sequence of the first reference signal.

Furthermore, according to the embodiment of the present invention, the common root sequence is determined according to the number of subcarriers, and the root sequence of the first reference signal is formed by truncating the number of bits from the common root sequence according to the predetermined positions of the subcarriers in the transmission frequency band. Furthermore, when data transmission is performed on the same time-frequency resource, reference signals with not exactly the same root sequence can be multiplexed.

Optionally, the common root sequence is the same as the root sequence of the first reference signal, and bits are truncated from the root sequence of the first reference signal to form all root sequences of the second reference signal.

Optionally, after step 303, the following steps are also performed:

Step 304: Analyze the root sequence of the first reference signal, and intercept the number of bits from the root sequence of the first reference signal to form a partial root sequence of the second reference signal.

Furthermore, in the embodiment of the present invention, the root sequence of the first reference signal and the root sequence of the second reference signal having overlapping bits are selected from the common root sequence. The reference signals with different root sequences are multiplexed during data transmission on the same time-frequency resource.

See specific examples below:

Step 301 may specifically be: divide the entire transmission frequency band into multiple transmission frequency subbands (subbands), assuming that the width of a certain transmission frequency subband occupies 1 to N subcarriers, and determine that the number of subcarriers in the transmission frequency subband is N, N is an integer greater than 0;

Step 302 is specifically: define a common root sequence with a length of N for the above-mentioned transmission frequency band subband It can be seen that the common root sequence has the same number of bits and N bits as the number of subcarriers;

Step 303 is specifically: different reference signals are intercepted on the common root sequence according to the pre-set positions of their own subcarriers in the transmission frequency band, and different cyclic shifts are used for the reference signals transmitted on the same subcarrier. For example, for selecting part of the number of digits from the common root sequence to form the root sequence of the first reference signal; if the first reference signal is preset to be transmitted on the subcarriers N ₁ to N ₂ of this transmission frequency subband, then only required from the sequence The N ₁ -N ₂ bits are intercepted as its own root sequence, where N1<N2<N.

Step 304: Analyze the root sequence of the first reference signal, and intercept bits from the root sequence of the first reference signal to form part or all of the root sequence of the root sequence of the second reference signal. Optionally, label the corresponding subcarriers according to the number of bits of the common root sequence, according to the overlapping conditions of the subcarrier numbers occupied by the root sequence of the first reference signal and the subcarrier numbers occupied by the root sequence of the second reference signal , intercepting overlapping bits from the root sequence of the first reference signal to form a partial root sequence of the second reference signal. Optional: after parsing the root sequence of the first reference signal, if it is obtained that the first reference signal and the second reference signal will be transmitted simultaneously on certain subcarriers, then the two reference signals should adopt different cyclic shifts. It can be understood that: a partial subsequence selected from the root sequence of the first reference signal is used as all or part of the subsequences of the root sequence of the second reference signal.

Optionally, the common root sequence is spliced by the root sequence of the first reference signal and the root sequence of the third reference signal; after step 304, further include:

Analyzing the root sequence of the third reference signal, and intercepting the number of bits from the root sequence of the third reference signal to form a partial root sequence of the second reference signal;

Partial root sequences respectively selected from the root sequence of the first reference signal and the root sequence of the third reference signal are spliced to form all root sequences of the second reference signal.

Specifically, the root sequence of the third reference signal is analyzed, and the number of bits is intercepted from the root sequence of the third reference signal to form a partial root sequence of the second reference signal, specifically including:

According to the number of bits of the common root sequence, the corresponding subcarriers are labeled, and according to the overlapping condition of the subcarrier numbers occupied by the root sequence of the third reference signal and the subcarrier numbers occupied by the root sequence of the second reference signal, from the third A partial root sequence of the second reference signal formed by intercepting overlapping bits from the root sequence of the reference signal.

As shown in FIG. 4 , in the first specific manner, the sub-carrier number of the sub-band of the transmission frequency band is 120 as an example, and the description is as follows.

Determine the length X of the "subband root and whisker column": the length of the subband root and whisker column has a direct correspondence with the number of subcarriers in the subband of the transmission frequency band occupied by the subband, such as X=N. For example, the sub-band bandwidth is 120 sub-carriers, and the length of the corresponding reference signal common root column is X=120 bits.

Generate Zadoff-Chu sequence: Find the largest prime number N less than X, and then generate a Zadoff-Chu sequence of length N according to the generation method of Zadoff-Chu sequence. The reason for this is that Zadoff-Chu is a special sequence , whose length is a prime number. Continuing the above example, assuming that the required common root sequence length is X=120, then find the largest prime number N=113 less than 120, and then generate the Zadoff-Chu sequence according to the following formula:

$\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;q</span>}\frac{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; lk</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

The parameters q and l in the expression belong to the system configuration. It can be understood that as long as N=113 is determined, a Zadoff-Chu sequence a(k) with a length of 113 can be generated.

Generating the subband root and whisker column: copy the first XN bits of the generated Zadoff-Chu sequence to the end of the sequence to generate a new sequence of length X, which is the subband root and whisker column of the common root and root column of the reference signal required. Continuing the above example, a Zadoff-Chu sequence a(k) with a length of N=113 is generated, and now the XN=7th bit of a(k) is copied to the end of the original sequence, so that a subband root and whisker sequence is obtained The length is 120.

The user corresponding to the first reference signal intercepts the "reference user list" according to the allocated resource position: firstly, the subcarriers occupied by the subbands are labeled according to k=0,1,...,X-1, and the users allocate according to their own The sub-carrier number occupied by the obtained resources, and the corresponding sequence is intercepted from the public sub-band root and whisker list as its own "user root and whisker list". Still according to the above example, assuming that the user is assigned to the 12th to 35th subcarriers for transmission, then from Parts of k=12, 13, ..., 25 are intercepted as user root and whisker columns of the first reference signal corresponding to the user.

When the user corresponding to the second reference signal intercepts the "reference user root and whisker column" according to the allocated resource location. Still according to the above example, assuming that the 18th to 70th subcarriers are allocated for transmission, then from The part of K=18, 19, ... 70 is intercepted as the user root and whisker column of the first reference signal corresponding to the user.

After analysis, it can be found that: in this scheme, the subcarriers allocated by the two users corresponding to the first reference signal and the second reference signal overlap K=18, 19,...25, then the two users transmit the reference on the overlapping subcarriers The contents of the root column of the signal are the same. Therefore, as long as the two users adopt different cyclic shifts, the channel estimation of the two users can be performed separately; for other non-overlapping parts such as the first reference signal K=12,13,...17, and the second reference signal K=26 , 27, ... 70, other channel estimation methods in the prior art can be used to perform channel estimation on two users respectively, which will not be described again.

It can be seen that the embodiment of the present invention selects the root sequence of the first reference signal and the root sequence of the second reference signal with overlapping subsequences (sequences of K=18, 19, ... 25) from the subsequences of the common root sequence. The reference signals with different root sequences are multiplexed during data transmission on the same time-frequency resource.

It can be seen that if the following conditions are met, different reference signals can be distinguished and independent channel estimation can be obtained:

1. On subcarriers that are transmitted jointly by different reference signals, it is not required that the root sequences of each reference signal be completely consistent, but that the content of the root sequences of each reference signal is required to be the same.

2. On the sub-carriers where different reference signals are transmitted together, each reference signal adopts a different cyclic shift.

The root sequence of each user can be obtained by intercepting or splicing. After satisfying the above conditions, independent channel estimation can be realized. The following three possible specific methods are listed below, but the actual methods are far more than these and cannot be listed one by one. As long as the above principles are satisfied, independent channel estimation can be performed.

Please refer to Fig. 5. In the second method, assuming that the subcarriers allocated by the second reference signal corresponding to user 2 are included in the subcarrier range of the first reference signal allocated by user 1, the corresponding subcarriers can be extracted from the root sequence of reference signal 1 sequence of length. The two require different cyclic shifts. An example is shown in the figure below. On the contrary, the root sequence of reference signal 2 may be generated according to the protocol, and reference signal 1 directly adopts the root sequence of reference signal 2 on the subcarriers for common transmission, and the root sequences of other subcarriers may have other generation methods, which are not limited .

Determine the length X of the root-and-whisker sequence of user 1: the length of the root-and-whisker sequence has a direct correspondence with the number of subcarriers occupied by user 1. For example, user 1 has allocated 72 sub-carriers, and the length of the corresponding reference signal string is X=72 bits. Generate Zadoff-Chu sequence: Find the largest prime number N less than X, and then generate a Zadoff-Chu sequence of length N according to the generation method of Zadoff-Chu sequence. The reason for this is that Zadoff-Chu is a special sequence , whose length must be a prime number. Continuing the above example, assuming that the length of the required root and whisker column is X=72, then find the largest prime number N=71 less than 72, and then generate the Zadoff-Chu sequence according to the following formula:

$\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;q</span>}\frac{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; lk</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The parameters q and l in the expression belong to the system configuration. It can be seen that the Zadoff-Chu sequence a(k) with a length of 71 can be generated if N=71 is determined. Generate user 1's root and hair column: copy the first XN digits of the generated Zadoff-Chu sequence to the end of the sequence, and generate a new sequence of length X, which is the user 1's root and hair column. Continuing the above example, a Zadoff-Chu sequence a(k) with a length of N=71 is generated. Now copy the XN=1th bit of a(k) to the end of the original sequence, so as to obtain the root column of user 1 The length is 72.

Obtain the root column of user 2: user 2 overlaps with user 1 according to the subcarriers allocated by user 2, from The corresponding short sequence is intercepted as its own root and whisker column. Assuming that the subcarrier occupied by user 2 overlaps with the 24th-47th subcarrier of the user, then user 2 intercepts The 24th-47th positions are listed as their own roots.

After a brief analysis, it can be found that this scheme can ensure that the two users transmit the same content of reference signals on overlapping subcarriers.

Please refer to FIG. 6. In the third specific method, assuming that the first reference signal 1 partially overlaps with the second and third reference signals, the corresponding sequence is intercepted from the root sequence of the second reference signal in the overlapping part with the second reference signal, and the third The overlapping part of the reference signal intercepts the corresponding sequence from the root sequence of the third reference signal, so as to obtain a root sequence of the spliced first reference signal. The first reference signal and the second and third reference signals use different cyclic shifts. In the example in the figure below, since the second reference signal and the third reference signal do not overlap in the frequency domain, the same cyclic shift can be used .

The root and whisker columns of users 2 and 3 are generated according to the prior art.

User 1 intercepts the corresponding subsequence from the root string of user 2 according to the subcarrier position overlapping with user 2.

User 1 intercepts the corresponding subsequence from the root string of user 3 according to the position of the subcarrier overlapping with user 3.

After concatenating the subsequences obtained in steps 2) and 3), the root and whisker column of user 1 is obtained.

Through such a design, the receiving end can also distinguish the multiplexed reference signals according to the cyclic shift, and obtain independent channel estimation. At the same time, the restriction that different reference signals must have the same length is canceled.

It can be seen from the description of the above embodiments, for the demodulation reference signal of uplink MU-MIMO. If two users adopt MU-MIMO, they do not need to completely overlap on the subcarriers, and the length of the reference signal is the same, but only the following two conditions can be met:

1. On subcarriers that are transmitted jointly by different reference signals, the content of the root sequence of each reference signal is required to be the same;

2. On the sub-carriers where different reference signals are transmitted together, each reference signal adopts a different cyclic shift.

Also for the uplink measurement reference signal in LTE. The present invention does not require that the multiplexed uplink reference signals all use the same length.

The embodiment of the present invention also provides a reference signal multiplexing device 700. The multiplexing device may be a terminal providing an uplink measurement reference signal, or a base station providing a downlink measurement reference signal. This embodiment is illustrated by taking an example applicable to an LTE advanced terminal, and the reference signal multiplexing device 700 includes:

Common root sequence generation module 710: used to determine the number of subcarriers on the transmission frequency band, and determine the common root sequence for the reference signal root sequence to be carried according to the number of subcarriers, and the number of bits of the common root sequence is the same as the number of subcarriers;

The first reference signal generating module 720: according to the predetermined position of the subcarrier of the first reference signal in the transmission frequency band, the number of bits is intercepted from the common root sequence to form the root sequence of the first reference signal.

Furthermore, according to the embodiment of the present invention, the common root sequence is determined according to the number of subcarriers, and the root sequence of the first reference signal is formed by truncating the number of bits from the common root sequence according to the predetermined positions of the subcarriers in the transmission frequency band. Furthermore, when data transmission is performed on the same time-frequency resource, reference signals with not exactly the same root sequence can be multiplexed.

Optionally, the first reference signal generation module is further configured to: intercept the number of bits from the root sequence of the first reference signal to form all the root sequences of the second reference signal, the common root sequence and the root sequence of the first reference signal The sequence is the same.

Please refer to FIG. 8 , the reference signal multiplexing device 700 further includes: a second reference signal generation module 730: analyze the root sequence of the first reference signal, and intercept the number of bits from the root sequence of the first reference signal to form the second reference signal part of the root sequence. Specifically, the second reference signal generation module 730: is also used to label the corresponding subcarriers according to the number of bits of the common root sequence, according to the number of subcarriers occupied by the root sequence of the first reference signal and the root of the second reference signal The overlap condition of the subcarrier numbers occupied by the sequences is to intercept the overlapping bits from the root sequence of the first reference signal to form a partial root sequence of the second reference signal.

Further: if the common root sequence is spliced by the root sequence of the first reference signal and the root sequence of the third reference signal, the second reference signal generating module 730 is further configured to: analyze the root sequence of the third reference signal, Intercepting the number of digits from the root sequence of the third reference signal to form a partial root sequence of the second reference signal; splicing the partial root sequences selected from the root sequence of the first reference signal and the root sequence of the third reference signal respectively to form the second The entire sequence of the reference signal.

To sum up, the embodiments of the present invention provide a reference signal multiplexing method and a base station, so that the root sequence of the first reference signal and the root sequence of the second reference signal with overlapping subsequences can be optionally extracted from the subsequences of the common root sequence. Furthermore, when data transmission is performed on the same time-frequency resource, reference signals with not exactly the same root sequence are multiplexed.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented through computer programs to instruct related hardware, and the programs can be stored in a computer-readable storage medium. During execution, it may include the processes of the embodiments of the above-mentioned methods. Wherein, the storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM) or a random access memory (Random Access Memory, RAM), etc.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (7)

1. A method for multiplexing an uplink reference signal, comprising: Determine the number of subcarriers on the transmission frequency band, the number of subcarriers refers to the number of subcarriers in the transmission frequency band, and the subcarriers are basic units in the frequency domain; Determine the common root sequence carried by the reference signal root sequence according to the number of subcarriers, and the number of bits of the common root sequence is the same as the number of subcarriers; According to the preset position of the subcarrier of the first reference signal in the transmission frequency band, the number of bits is intercepted from the common root sequence to form the root sequence of the first reference signal; The common root sequence is the same as the root sequence of the first reference signal, and the number of bits is intercepted from the root sequence of the first reference signal to form all the root sequences of the second reference signal; or, the method further includes: parsing the first For the root sequence of the reference signal, the number of bits is intercepted from the root sequence of the first reference signal to form a partial root sequence of the second reference signal. 2. The method according to claim 1, wherein the root sequence of the first reference signal is analyzed, and the number of digits is intercepted from the root sequence of the first reference signal to form a partial root sequence of the second reference signal, specifically comprising: According to the number of bits of the common root sequence, the corresponding subcarriers are marked, and according to the overlapping condition of the subcarrier numbers occupied by the root sequence of the first reference signal and the subcarrier numbers occupied by the root sequence of the second reference signal, from the first Intercepting overlapping bits in the root sequence of the reference signal constitutes a partial root sequence of the second reference signal. 3. The method according to claim 1, wherein the common root sequence is spliced by the root sequence of the first reference signal and the root sequence of the third reference signal; The method further comprises: Analyzing the root sequence of the third reference signal, and intercepting the number of bits from the root sequence of the third reference signal to form a partial root sequence of the second reference signal; Partial root sequences respectively selected from the root sequence of the first reference signal and the root sequence of the third reference signal are spliced to form all root sequences of the second reference signal. 4. The method according to claim 3, wherein the root sequence of the third reference signal is analyzed, and the number of digits is intercepted from the root sequence of the third reference signal to form a partial root sequence of the second reference signal, specifically comprising: According to the number of bits of the common root sequence, the corresponding subcarriers are labeled, and according to the overlapping condition of the subcarrier numbers occupied by the root sequence of the third reference signal and the subcarrier numbers occupied by the root sequence of the second reference signal, from the third A partial root sequence of the second reference signal formed by intercepting overlapping bits from the root sequence of the reference signal. 5. A multiplexing device for an uplink reference signal, comprising: Common root sequence generation module: used to determine the number of subcarriers on the transmission frequency band, determine the common root sequence for the reference signal root sequence to be carried according to the number of subcarriers, the number of bits of the common root sequence is the same as the number of subcarriers, and the subcarriers The number of carriers refers to the number of subcarriers in the transmission frequency band, and the subcarriers are the basic units in the frequency domain; The first reference signal generation module: according to the preset predetermined position of the subcarrier of the first reference signal in the transmission frequency band, the number of bits is intercepted from the common root sequence to form the root sequence of the first reference signal; The first reference signal generation module is further configured to: intercept the number of bits from the root sequence of the first reference signal to form all the root sequences of the second reference signal, the common root sequence is the same as the root sequence of the first reference signal; or , The multiplexing device further includes: a second reference signal generation module: analyzing the root sequence of the first reference signal, and intercepting the number of bits from the root sequence of the first reference signal to form a partial root sequence of the second reference signal. 6. The multiplexing device according to claim 5, further comprising: The second reference signal generating module: used to label the corresponding subcarrier according to the number of bits of the common root sequence, according to the subcarrier number occupied by the root sequence of the first reference signal and the subcarrier number occupied by the root sequence of the second reference signal The overlapping condition of the carrier number is to intercept the overlapping bits from the root sequence of the first reference signal to form a partial root sequence of the second reference signal. 7. The multiplexing device according to claim 5, wherein the common root sequence is spliced by the root sequence of the first reference signal and the root sequence of the third reference signal; The second reference signal generation module is also used to: analyze the root sequence of the third reference signal, intercept the number of digits from the root sequence of the third reference signal to form a part of the root sequence of the second reference signal; part of the root sequence selected from the root sequence and the root sequence of the third reference signal to form the entire root sequence of the second reference signal.