WO2007022715A1

WO2007022715A1 - A method, system and terminal for multiplexing uplink pilot based on single carrier frequency division multiple access

Info

Publication number: WO2007022715A1
Application number: PCT/CN2006/002147
Authority: WO
Inventors: Sha Ma; Yujuan He
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2005-08-23
Filing date: 2006-08-23
Publication date: 2007-03-01
Also published as: CN101176285B; CN1801680A; CN101176285A

Abstract

A method for multiplexing uplink pilot based on single carrier frequency division multiple access, comprises the steps: the user terminal transmits the pilot signal on several sub-carriers within a symbol; and in the other symbol, transmits the pilot signal on several sub-carriers which interleaves with the sub-carrier occupied in the previous symbol; time division multiplexes the said respective signal with the symbol in which the user terminal transmit the data signal. Wherein the user terminal could transmit the pilot signal on several sub-carriers within the said symbol under the direction of the network side. The invention also provides a user terminal and a method for multiplexing uplink pilot based on single carrier frequency division multiple access accordingly. The invention could decrease the interval between the sub-carriers occupied by pilot signal on the frequency field, and thus achieve better interpolation processing effect.

Description

Uplink pilot multiplexing method, system and terminal based on single carrier frequency division multiple access

The present invention relates to the field of wireless communication technologies, and in particular, to a method and system for uplink pilot multiplexing based on single carrier frequency division multiple access, and a user terminal. Background technique

In recent years, multi-carrier technology has become a hotspot technology for broadband wireless communication. The basic idea is to divide a wideband carrier into multiple subcarriers and transmit data in parallel on multiple subcarriers. Generally, the width of the subcarrier is smaller than the coherence bandwidth of the channel, so that the fading of each subcarrier is flat fading on the frequency selective channel, which can reduce crosstalk between data symbols, and does not require complicated channel equalization, and is suitable for high rate. Data transfer. Multi-carrier technology usually uses frequency domain channel estimation techniques and frequency domain equalization techniques. Some single-carrier systems can also perform a single-carrier system equivalent to a system composed of multiple parallel sub-carriers by performing Fourier Transformation (FFT) at the receiving end for frequency domain channel estimation and frequency domain equalization processing.

The frequency domain channel estimation usually adopts a coherent demodulation method based on auxiliary information, and some known pilot symbols or training sequences are inserted at some fixed positions of the signal transmitted by the transmitting end, and the pilot signals are used according to an algorithm at the receiving end. Perform frequency domain channel estimation. In the frequency domain estimation of the channel, the system has a time-frequency two-dimensional structure (instant domain and frequency domain), so the pilot symbol design used here should take into account the time-frequency two-dimensional correlation characteristics of the channel as much as possible. Wherein, as long as the interval of the pilot symbols in the time and frequency directions is sufficiently smaller than the correlation time of the channel and the channel coherence bandwidth, the channel transmission function of the inserted pilot symbol position can be better estimated at the receiving end, and then adopted. A two-dimensional interpolation method is used to estimate the channel response of all data symbol positions. Therefore, the design of the inserted pilot symbols is increasingly becoming a key issue in systems employing frequency domain channel estimation and frequency domain equalization processing.

In the uplink of a wireless communication system, the peak-to-average ratio of the transmitted power is a non-negligible problem, which directly affects the effectiveness and power consumption characteristics of the user terminal power amplifier. The existing single-carrier frequency division multiple access technology compares the peak-to-average ratio of the transmitted power by carrying the signal on the time domain waveform Low; At the same time, the time-frequency resources occupied by different users also do not intersect each other, so that the interference between different users in the cell can be reduced. Single-carrier technology can be implemented by time domain processing or by frequency domain processing. The implementation of time domain processing is called Interleaved Frequency Division Multiple Access (IFDMA); its frequency domain processing The implementation method is called Discrete Fourier Transform (DFT-S-OFDMA), and both of the implementations can achieve low emission power peaks. Time domain waveform. The difference between the two implementations lies in the processing of the transmitted data, wherein the IFDMA based on time domain processing implements the comb spectrum in the frequency domain by repetition of the time domain; and the DFT-S-OFDMA based on the frequency domain processing Then, the comb 镨 is constructed directly according to the frequency domain feature, and then the time domain waveform is formed by the inverse fast Fourier transform (IFFT) processing. The specific processing procedure of the comb spectrum in the single carrier frequency division system using the time domain processing process and the frequency domain processing procedure will be separately described below.

1. Time domain processing implementation process Here, the Q data symbols of a certain user i may be a real number or a complex number to form a data block block, wherein each data symbol has a duration of 7 and a data block block of the user. Can be expressed as d(') = [Ci'), '"^ ] ⁷ (where τ represents the matrix transpose), now compress the data symbol in the data block block from the data symbol duration 2; into the chip The time length T _c , and then the data block block is repeated twice, and the data symbols after the repeated processing are:

^C ( )

The times represents the number of repetitions of the data block block, and the data symbols after the repeated processing can be further expressed as:

^C ' ^ ^de ' ^{l = 0} -' ^QL - where η χΐ β denotes the modulo 2 operation.

The sequence of data symbols thus obtained after repeated processing appears as a set of comb-like frequency patterns on the frequency axis, as shown in FIG.

Since each user's data block block undergoes the same processing as described above, it exhibits the same comb spectrum on the frequency axis, and in order to avoid mutual interference between multiple users, it is necessary to The comb spectra are interlaced with each other, so you need to select a set of user-specific phase vectors here: = _eX p{- /·Φ(')} , / = 0,...,2 - 1 , QL , where the user represents the phase vector, and Φ represents the phase rotation factor;

The obtained phase vector of the user i is multiplied by the element obtained as described above, and finally the useful data portion of the transmitted signal of the user i is:

In actual processing, further protection time is needed to reduce or eliminate data intersymbol interference caused by channel multipath delay, where the added protection time requirement is ⁷¹ Α (where

Γ _δ represents the added guard time value, _raax represents the maximum multipath delay spread of the channel); meanwhile, in order to simplify the frequency domain equalization process at the receiving end, a cyclic prefix (CP, cyclic prefix) is added before the signal symbol is transmitted, that is, every The symbol at the end of the transmitted signal symbol is copied to the beginning of the signal symbol, and the resulting symbol length of the transmitted signal will become ^{+ T} S and the receiving end will remove the redundancy of the CP portion before processing the received signal.

Correspondingly, at the receiving end, the comb spectrum of multiple users needs to be separated, and the respective repeated data symbols are combined; at the same time, a frequency domain equalizer needs to be introduced to resist the data symbols in the data block caused by the wireless transmission process. Interfere with ISI. The maximum number of multiplexed users that can be supported by the single-carrier frequency division multiplexing system implemented by IFDMA will not exceed the number of repetitions of its data blocks.

2. Frequency domain processing implementation process (DFT-S-OFDMA)

As shown in FIG. 2, the implementation principle of the existing DFT-S-OFDMA is as follows: The transmitting end first performs the discrete Fourier transform (DFT, Discrete Fourier Transform) processing on the transmitted time domain data, that is, performs pre-transmission time domain data. Precoding "operation; then frequency domain windowing of the DFT processed frequency domain data to further reduce the peak-to-average ratio of the pre-transmitted time domain data (this process is optional); then the frequency domain according to a predetermined mapping rule The data is mapped to a wider frequency band, and finally the inverse frequency inverse Fourier transform (IFFT) is performed on the mapped frequency domain data to obtain a corresponding time domain waveform.

The key step in this process is the mapping of frequency domain data, if DFT and IFFT The number of transformation points is equal, then the mapping is - corresponding, at this time DFT processing and IFFT processing completely canceled, equivalent to a single carrier link; and if the length of the DFT is smaller than IFFT, then it needs to be processed by equal interval , which is:

. ' , [- 1], 0,... ,0, X[0], 0,... ,0, Χ[\],· '

And obtaining a comb spectrum (shown in FIG. 1) which is the same as the frequency formed by repeating the data block L times in the time domain processing manner, wherein each X[m] in the matrix represents a DFT transform. The obtained frequency domain samples are distinguished by different frequency domain subcarrier offsets, which is equivalent to the user phase rotation in the IFDMA system.

The time domain waveform processed by the above process also needs to be operated by adding CP.

Correspondingly, after removing the CP at the receiving end, the corresponding first needs to perform FFT processing on the data after removing the CP, and then separate the comb spectrum of different users according to the mapping rule of the transmitting end, and then perform IDFT after frequency domain equalization processing. To obtain time domain data required for demodulation processing. Similarly, the maximum number of multiplexed users that can be supported by the single-carrier frequency division multiple access system implemented by the frequency domain processing method will not exceed the number of repetitions L of its data blocks.

In the single carrier frequency division multiple access system implemented by the frequency domain processing implementation described above, each user needs at least one subcarrier system (ie, a "comb tooth" of a set of frequency subcarriers) through frequency domain subcarrier mapping processing. The subcarriers are distributed over the entire frequency band. From the frequency point of view, when the user's signal symbols are transmitted through the actual channel, they experience different frequency fading, and thus have the effect of frequency diversity.

In an actual single-carrier frequency division multiple access system, each user is required to provide uplink symbols to the receiver for frequency domain channel estimation, and is transmitted in a single carrier frequency division multiple access system. The signal uses time domain waveforms to carry information, and in order to avoid causing excessive peak-to-average ratio, a method of time-division multiplexing of pilot symbols and data symbols is selected. However, the use of pilot symbols also needs to consider the problem of efficiency. The principle of design is that the resources of pilot symbols occupy less than 20% of all symbol resources (sum of pilot symbols and data symbols); and in order to track time-varying Channel, if the user's moving speed is relatively high, when a transmission time interval (TTI, Transmission Time Interval) is 0.5ms or longer, multiple scattered pilot symbols are needed in one TTI, obviously The structure in which the pilot symbols are shorter than the data symbols easily meets the requirements of the above conditions: It is possible to ensure that the occupancy of the symbol resources is low and the time-varying channel can be tracked. In the prior art, for convenience of processing, it can be assumed that the pilot symbol is set to half the length of the data symbol, which is called "half symbol pilot", as shown in FIG. 3, which is a typical half symbol pilot. A schematic diagram of a TTI structure in which two short pilot symbols are included in the TTI and are dispersed between data symbols within one TTI.

Taking the TTI structure shown in FIG. 3 as an example, such a TTI structure satisfies the design requirements, but in practical applications, especially in the multiple access mode in a single carrier system, the half symbol pilot mode brings other problem. In digital signal processing, the length of time determines the granularity of the digital frequency in the frequency domain. The pilot symbols and the data symbols are not equal in length, which will cause the pilot symbols of the user and the frequency components of the data symbols in the frequency domain to be out of phase. correspond. That is, after transmission over the wireless channel, the pilot symbols are not able to directly provide fading information experienced by all frequency components of the data symbols, which may affect the demodulation performance of the received signal symbols. The reasons for this defect will be specifically explained below:

In digital signal processing, FFT/IFFT transform pairs are commonly used to represent the time domain waveform and frequency domain representation of signal symbols, namely:

Z[m] =∑x(«)exp(-;2^— ) _W = 0,1,··· , N - 1 [ ] denotes the frequency domain representation, ie each sub-rt=0 N

Carrier wave

x{n) = ) indicates various waveforms of the time domain

Point

According to the comb spectrum time domain processing method in the single carrier system above, in the time division multiplexing structure of the half symbol pilot and the data symbol, the data symbol and the pilot symbol have different phase rotation factors: the phase of the user i data portion The rotation factor is φ( _{0 =} /. , = 0,l,..., -1 . To support the same number of users, the phase rotation factor of the pilot portion of the half symbol length is:

Φ'(/) = i = 2i = 2Φ(ζ), i = 0,1,..., L - 1

(Q/2)-L Q L

It is assumed above that Q and L are even numbers, and the data symbols and the repeated parts of the pilot symbols are respectively written out, and the transmitted signal symbols of the obtained data portions are:

-- β β22 _γ ('·) _ Γ _Ρ ( ( „-Μ ... ρ(0 -;·(Λί-ΐ)Φ( -]Γ The transmitted signal symbol of the pilot part is:

V (') - "(·('·) _P ('') „-y2O( ...

ρ l>0, ^e ,

The obtained data symbols and the time domain signals of the pilot symbols are respectively FFT-transformed into the frequency domain, and the respective frequency components are respectively obtained:

X _d ["'] = exp( - 2π 3⁄4 ) exp( -J2,≡-) = 3⁄43⁄4) exp( - jln i^± iliL)

N-0 ti^ i L ,, _{= 0} (JL

m = 0,1,·.. ,QL ― 1,/ = 0,1,·'·, a 1

X„W = exp( - jln ² ( )'")

m = 0,1,··· - l;i = 0,1,··· ,i - 1

2

Obviously, the frequency component contained in the pilot portion shown in the above formula is half of the data portion, and since the length of the pilot symbol is exactly half of the data symbol, the frequency component interval of the pilot symbol is exactly the data symbol frequency component interval. Twice, that is, the subcarrier spacing is not the same, as shown in Figure 4.

In order to perform effective frequency domain equalization processing at the receiving end, it is necessary to obtain channel information of the same frequency granularity as the data symbols, and frequency domain interpolation processing is performed for this purpose. The principle of interpolating the frequency domain channel estimation result is as follows: ^ The interval between the two frequency points is within the channel coherence bandwidth, and the intermediate frequency points are obtained by using the correlation. At present, the FFT interpolation algorithm is usually selected, and the steps of frequency domain channel estimation and interpolation processing at the receiving end are as follows:

The pilot signal symbol _X will be received first. ⁽ⁱ⁾ performing an FFT transform into the frequency domain, the transform length is

Frequency domain channel estimation is performed by using a known transmitted pilot signal to obtain 个 £ frequency points; then the channel obtained by estimating the frequency domain channel is subjected to IFFT transform into the time domain, and the transform length is

And the zero-time processing of the transformed time domain signal is performed, and the FFT transformation of the QL point is performed: X _p [m]= 3⁄4"c<'> exp( -]2π 3⁄4exp( - jln -) = ') exp( - jln ^(, ")'")"=oy JL, ,, ₌₀ { L

m = 0,1,··· ,QL一 l;i = 0,1,·- , L - 1

Thereby obtaining a channel frequency domain response with a frequency granularity equal to the data portion;

Finally, the obtained channel frequency response can be used to calculate the coefficients of the frequency domain equalizer, thereby performing frequency domain equalization processing on the received data signal symbols.

In the single-carrier comb spectrum system, when the interval of the subcarriers occupied by the pilot symbols of one user is relatively large, such as greater than the coherent bandwidth, the effect of the above-mentioned frequency domain interpolation processing is not ideal, resulting in channel estimation. The accuracy will also be lower. Summary of the invention

The invention provides an uplink pilot frequency multiplexing method based on single carrier frequency division multiple access, so as to reduce pilot subcarrier spacing occupied by pilot symbols in the frequency domain, thereby obtaining better interpolation processing effect and improving channel estimation. The accuracy.

Correspondingly, the present invention also proposes an uplink pilot multiplexing system based on single carrier frequency division multiple access and a user terminal thereof.

In order to solve the above problems, the technical solution proposed by the present invention is as follows:

An uplink pilot multiplexing method based on single carrier frequency division multiple access includes the following steps:

The user terminal occupies several subcarriers in one symbol for pilot signal transmission; and

Pilot signal transmission is performed in at least one other symbol occupying a plurality of subcarriers interleaved with the subcarriers existing in the previous symbol; the symbols are time division multiplexed with the symbol of the user terminal transmitting the data signal.

Preferably, the length of each symbol is less than the length of time that the user terminal transmits the symbol of the data signal.

Preferably, the frequency band in which the plurality of subcarriers respectively occupied by the user terminal in the respective symbols overlaps with the frequency band occupied by the user terminal in the symbol of the transmitted data signal.

A user terminal based on single carrier frequency division multiple access, comprising: Means for occupying a number of subcarriers in one symbol and occupying a number of subcarriers interleaved with a subcarrier presence position occupied in the previous symbol in at least one other symbol; and

Means for performing pilot signal transmission based on each subcarrier occupied in each symbol; the symbols are time division multiplexed with symbols of the user terminal transmitting the data signal.

The network side divides each user terminal that participates in uplink pilot multiplexing into different user terminal groups; and separately allocates pilot multiplexing resources for each user terminal group;

The network side allocates the pilot multiplexing resources allocated to each user terminal group to each user terminal in the group respectively;

Each user terminal occupies a plurality of subcarriers in a specified symbol for pilot signal transmission according to a pilot multiplex resource indication delivered by the network side;

Pilot signal transmission is performed in at least one other symbol occupying a plurality of subcarriers that are not identical to the subcarriers occupied in the designated symbol; the symbols are time division multiplexed with the symbol of the user terminal transmitting the data signal.

Preferably, each user terminal performs cyclic shift of the same shift amount for each subcarrier in each of at least another symbol with reference to each subcarrier position occupied in the designated symbol; Each subcarrier determined later performs pilot signal transmission.

An uplink pilot multiplexing system based on a single carrier frequency division multiple access, comprising a network side and a user terminal side, wherein the network side includes:

A unit for dividing each user terminal participating in uplink pilot multiplexing into different user terminal groups;

Means for respectively assigning pilot multiplexing resources to the user terminal groups; and

And a unit for transmitting the pilot multiplexing resources allocated to each user terminal group to each user terminal in the group;

The user terminal side includes: Means for occupying several subcarriers in a specified symbol according to a pilot multiplexing resource indication delivered by the network side, and occupying a plurality of subcarriers that are not identical to the subcarriers occupied in the specified symbol in at least one other symbol ; with

Means for performing pilot signal transmission based on each subcarrier occupied in each symbol; the symbols are time division multiplexed with symbols occupied by the user terminal transmitting the data signal.

Preferably, the unit for occupying the subcarrier in each symbol in the user terminal performs the same shift amount for each subcarrier in each of the at least one other symbol with the position of each subcarrier occupied in the designated symbol as a reference. Cyclic shift, and occupy each subcarrier determined after shifting.

Preferably, the frequency band in which the plurality of subcarriers respectively occupied by the unit for occupying the subcarrier in each symbol in the respective symbols overlaps with the frequency band occupied by the user terminal in the symbol for transmitting the data signal.

The beneficial effects that can be achieved by the present invention are as follows:

The technical solution of the present invention mainly enables the user terminal to perform pilot signal transmission in a plurality of symbols (these symbols are time-division multiplexed with the symbol of the user terminal transmitting the data signal), by occupying a plurality of subcarriers in which the positions are staggered. The user terminal may occupy a number of subcarriers that meet the requirements on the symbols, or may occupy a number of subcarriers that meet the requirements on the symbols under the indication of the network side. In the single carrier frequency division multiple access system, the user performs frequency domain multiplexing on multiple pilot symbols, and the receiving end combines the pilot subcarriers on multiple symbols to reduce the occupation of the pilot. The frequency subcarrier average interval, thereby increasing the frequency domain sampling rate, thereby improving the effectiveness of frequency domain channel estimation and interpolation processing, and the accuracy of channel estimation. DRAWINGS

Figure 1 is a schematic diagram showing the shape of a comb-like spectrum of a sequence of data symbols obtained after repeated processing of a data block on a frequency axis;

2 is a schematic diagram of an implementation principle of an existing DFT-S-OFDMA;

3 is a schematic diagram of a typical TTI structure using a half symbol pilot;

4 is a frequency component interval of a data symbol after using a half symbol pilot and a frequency of a pilot symbol. Schematic diagram of the relationship between component intervals;

FIG. 5 is a flowchart of a main implementation principle of a pilot multiplexing method based on a single carrier frequency division multiple access technique according to the present invention;

6 is a flowchart of a main implementation principle of a second pilot multiplexing method based on single carrier frequency division multiple access (OFDM) technology according to the present invention;

7 is a schematic diagram of a first example multiplexing manner of data symbols and pilot symbols given by four users in accordance with the principle of the method of the present invention;

8 is a schematic diagram of a second example multiplexing manner of data symbols and pilot symbols given by four users in accordance with the principle of the method of the present invention;

9 is a schematic diagram of a third example multiplexing manner of data symbols and pilot symbols given by four users in accordance with the principle of the method of the present invention;

10 is a schematic diagram of a fourth example multiplexing manner of data symbols and pilot symbols given by taking six users and three pilots as an example according to the principle of the method of the present invention;

FIG. 11 is a schematic diagram of a fifth example multiplexing manner of data symbols and pilot symbols given by taking 6 users and 3 pilots as an example according to the principle of the method of the present invention. detailed description

The design of the present invention is to provide a scheme in which multiple users can frequency-multiplex multiplex pilot symbols, so that the interval between pilot sub-carriers in the frequency domain of pilot symbols becomes smaller, so as to obtain a better channel. Estimate the effect of interpolation processing.

The main implementation principles of the present invention and its specific embodiments will be explained in detail below in conjunction with the accompanying drawings.

Please refer to FIG. 5 , which is a flowchart of a main implementation principle of a pilot multiplexing method based on single carrier frequency division multiple access (OFDM) technology, which is mainly used in a channel estimation period (such as a channel or Within a few TTIs, at least two pilot multiplexed processing is performed between the symbol-time multiplexed pilot symbols of the data signal transmitted by the user, and the main implementation process is as follows: Step 10: In a single carrier frequency division multiple access system, the user terminal occupies several subcarriers in one symbol, and performs pilot signal transmission processing based on the occupied plurality of subcarriers; the symbol and the symbol of the user terminal transmitting the data signal Time division multiplexing, and the length of the symbol is smaller than the length of time for the user terminal to transmit the data signal, that is, the symbol used for transmitting the pilot signal and the symbol for transmitting the data signal do not overlap in the time domain, and are smaller than The length of time the user sends the symbol of the data signal.

Step 20: The user terminal occupies a plurality of subcarriers interleaved with the subcarrier existence position occupied in the foregoing symbol in at least another symbol, and performs a transmission process of the pilot signal based on the occupied several subcarriers; The relationship between each symbol and the symbol of the user terminal transmitting the data signal is the same as described above, that is, each symbol does not overlap with the symbol for transmitting the data signal in the time domain, and is smaller than the length of time that the user transmits the symbol of the data signal.

The frequency band in which the plurality of subcarriers occupied by the user terminal in the symbol for transmitting the pilot signal may overlap with the frequency band occupied by the user terminal in the symbol for transmitting the data signal.

Please refer to FIG. 6 , which is a flowchart of a main implementation principle of a second pilot multi-frequency frequency division multiple access based pilot multiplexing method according to the present invention, which relates to multiple participating pilot multiplexing on the network side. The user terminal performs the process of grouping, and the user terminal in the group performs pilot multiplexing processing according to the indication of the network side. The main implementation process is as follows:

Step 100: The network side divides each user terminal that participates in uplink pilot multiplexing into different user terminal groups.

Step 110: The network side separately allocates corresponding pilot multiplexing resources for each of the user terminal groups separated by the foregoing;

Step 120: The network side separately distributes the pilot multiplexing resources allocated to each user terminal group to each user terminal in the corresponding group;

Step 130: Each user terminal first occupies several subcarriers in a specified symbol according to the pilot multiplexing resource indication information sent by the network side, and performs pilot signal transmission processing based on the occupied subcarriers; The specified symbol does not overlap with the symbol of the user terminal transmitting the data signal in the time domain (instant time multiplexing). Step 140: The network side performs, in at least another symbol, a transmission process of a pilot signal by using a plurality of subcarriers that are not identical to the subcarriers occupied in the designated symbol (that is, may be completely different or partially different); preferably The user terminal may perform cyclic shift processing of the same shift amount on each subcarrier by using each subcarrier position occupied in the designated symbol as a reference on other additional symbols, and then occupy each sub-determined after the shift processing. The carrier performs transmission processing of the pilot signal. The relationship between each of the other symbols mentioned herein and the symbol of the user terminal transmitting the data signal is the same as described above, i.e., each symbol does not overlap with the symbol used to transmit the data signal in the time domain.

Similar to the above method 1, the frequency band in which the plurality of subcarriers occupied by the user terminal in each symbol for transmitting the pilot signal may overlap with the frequency band occupied by the user terminal in the symbol for transmitting the data signal.

The following specific examples are given to describe the specific implementation principles of the solution of the present invention:

According to the characteristics of the time domain implementation based on the single carrier frequency division multiple access system described in the prior art, assuming that the phase rotation factor of the kth user data symbol is Φ( ), the pilot of one half of the user length of the user The phase rotation factor of the symbol is 2Φ, of which

Medium L indicates the number of repetitions of the data block, and [J indicates rounding down.

7 is a schematic diagram of a first example multiplexing manner of data symbols and pilot symbols given by four users according to the principle of the above method of the present invention, that is, when = 4; =: 0, 1, 2, 3, According to the above formula, the corresponding correspondence is 0, 2, 1, and 3, that is, when there are 4 users performing single-carrier frequency division multiplexing, the phase offsets of the 4 users in the data portion are 0, 1, respectively. 2,3, and the phase offset in the pilot portion is 0, 2, 1, 3, respectively, and the phase rotation is in two steps, which is equivalent to each of the two comb teeth in the data portion. The users are grouped into two groups, and the two users alternately occupy pilot subcarriers that have spectral overlap with their own data subcarriers. That is to say, the order of user multiplexing in the data is 0, 1, 2, 3, and the order of user multiplexing in the pilot is 0, 2, 1, and 3.

Usually, in a channel estimation period, pilot symbols of multiple times are used, and Figure 8 shows an example. Based on this principle, the present invention also proposes to set the phase rotation factor of the pilot symbol of the second half symbol length of the kth user to 2Φ(_), where = ((/c + l)mod2) ~ + ie when = 4; fc = 0,1,2,3, according to the above formula corresponding to get j = 2,0,3,1, that is to say in the second In the pilot symbol, the phase offsets of the four users are 2, 0, 3, 1, respectively, and the phase rotation is performed in twice the step size, which is equivalent to the user division of each of the two comb teeth in the data portion. For a group (ie, user 0, 1 is a group, users 2, 3 are a group), in the first pilot symbol, users 0, 1 are interleaved with each other and the data subcarriers of user 0 have spectral overlap. The frequency subcarriers, the users 2, 3 interleaved and the data subcarriers of the user 2 have spectrally overlapping pilot subcarriers; in the second pilot symbol, the two users in the same group exchange the sequences, and then interleaved and occupied Corresponding pilot subcarriers (ie, pilot subcarriers that are also interleaved with users 0 and 1 and have data overlaps with user 0's data subcarriers, user 2, 3 interleaved and user 2's data subcarriers have spectral overlap Pilot subcarriers). That is to say, in the data symbol, the user is based on the multiplexing order in the frequency domain is 0, 1, 2, 3, and in the first pilot symbol, the frequency domain-based multiplexing order of the user is 0, 2, 1, 3. In the second pilot symbol, the user is based on the multiplexing order in the frequency domain is 1, 3, 0, 2. Specifically, as shown in FIG. 8 , a schematic diagram of a multiplexing manner of a second embodiment of data symbols and pilot symbols given by taking four users as an example according to the above method of the present invention;

As shown in FIG. 8, in such a pilot multiplexing mode, subcarriers occupied by two pilot symbols of the same user in one channel estimation period and data subcarriers occupied in data symbols are interleaved. In the state, the receiving end may combine the subcarriers in the two pilot symbols, which is equivalent to reducing the subcarrier spacing of the pilot symbols in the frequency domain, as shown in FIG. 7 by user 0, respectively occupying two pilot symbols. The number of pilot subcarriers is half of the number of data subcarriers occupied in the data symbols. The receiving end combines the pilot subcarriers of the two pilot symbols to obtain the pilot subcarrier spacing of user 0. The interval of the data subcarriers is the same. In this case, the receiving end does not need to perform interpolation processing. (Of course, if the pilot subcarriers in the two pilot symbols are combined, interpolation processing is required, and the above prior art can be adopted. The FFT interpolation algorithm performs the difference processing), and a better interpolation processing effect can be obtained.

Of course, it is not necessary to divide the users whose frequency domain combs are adjacent into one group, any two users. The pilot subcarriers are used, and the pilot subcarriers occupied by the users in the group do not necessarily overlap with the data subcarriers occupied by the users in the group. FIG. 9 is a schematic diagram showing a third example multiplexing manner between data symbols and pilot symbols given by four users according to the principle of the method of the present invention; as shown in the figure, users 0 and 2 are divided. As a group, and dividing users 1 and 3 into groups, where users 0 and 2 alternately occupy subcarriers overlapping with data subcarriers occupied by user 2 on data symbols, respectively, between different pilot symbols, and the user 1, 3 alternately occupying subcarriers overlapping with data subcarriers occupied by user 0 on the data symbols, respectively, between different pilot symbols.

Certainly, when the single carrier frequency division multiplexing system configures three or more pilot symbols dispersed in time for the user, the same group of users may be alternately occupied and users between the multiple pilot symbols. The pilot subcarriers that occupy the closest (or overlapping) data subcarrier positions.

In addition, more than two users may be selected for packet processing, and the same group of users alternately occupy pilot subcarriers between multiple pilot symbols according to a prescribed rule, so that the pilot subcarrier position and the user are in the data. The data subcarrier positions occupied in the symbol are closest (or overlap). FIG. 10 is a schematic diagram showing a fourth example multiplexing manner of data symbols and pilot symbols given by taking six users and three pilot symbols as an example according to the principle of the method of the present invention, where users 0, 1, and 2 are shown. Divided into a group, the users 3, 4, 5 are grouped into one group, and the users 0, 1, and 2 respectively occupy the spectrum overlap of the data subcarriers occupied by the data symbols on the three pilot symbols respectively. The pilot subcarriers, the users 3, 4, 5 respectively occupy the pilot subcarriers whose spectrum overlaps with the data subcarriers occupied by the users 4 and 5 on the data symbols on the 3 pilot symbols.

FIG. 11 is a schematic diagram of a fifth example multiplexing manner of data symbols and pilot symbols given by taking six users and three pilot symbols as an example according to the method of the present invention, where each user in pilot 2 is occupied. The pilot subcarrier position is a cyclic shift of the pilot subcarrier positions in the pilot 1, and the pilot subcarrier shift amounts of different users are the same, and the pilot subcarriers occupied by the users in the pilot 3 are The location is another cyclic shift of the pilot subcarrier positions in the pilot 1. After multiplexing in this manner, each user's pilot subcarrier has a frequency domain of 3 pilot symbols. Smaller subcarrier spacing.

Based on the first method principle of the above described invention, the present invention will have the ability to implement the method The user terminal of the principle is also included in the protection scope, that is, in the user terminal claimed by the present invention, a unit is included, which is capable of performing the occupation of several subcarriers in one symbol and occupying the previous one in at least one other symbol. The subcarriers occupied in the symbols have the processing of a plurality of subcarriers interleaved at a position, and another unit capable of performing transmission processing of pilot signals based on the respective subcarriers occupied in the respective symbols described above, wherein each of the references mentioned herein The symbol used to transmit the pilot signal is time division multiplexed with the symbol of the user terminal transmitting the data signal (ie, does not overlap in the time domain).

Based on the foregoing second method principle of the present invention, the system in which the present invention is capable of implementing the principle of the method is also included in the protection scope, that is, in the uplink pilot frequency multiplexing system based on single carrier frequency division multiple access proposed by the present invention. The network side includes a unit for dividing each user terminal participating in uplink pilot multiplexing into different user terminal groups; a unit for separately assigning pilot multiplexing resources to each user terminal group; and for assigning to The pilot multiplexing resources of each user terminal group are respectively delivered to the units of each user terminal in the corresponding group.

The user terminal side includes a pilot multiplexing resource indication information that is sent according to the network side, occupies several subcarriers in a specified symbol, and occupies the subcarrier occupied in the specified symbol in at least another symbol. a unit of several subcarriers having different carriers, and a unit for transmitting pilot signals based on respective subcarriers occupied in each symbol, wherein each symbol for transmitting a pilot signal is occupied by a signal transmitted by a user terminal Symbol time division multiplexing (ie, no overlap in the time domain). Similarly, the unit for occupying subcarriers in each symbol included in the user terminal side may perform respectively on each subcarrier by using, in the at least another symbol, each subcarrier position occupied in the designated symbol as a reference. The cyclic shift of the same shift amount is implemented by occupying each subcarrier determined after the shift.

It is apparent that those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of the inventions

Claims

Rights request

1. An uplink pilot multiplexing method based on single carrier frequency division multiple access, characterized in that it comprises the steps of:

The user terminal occupies several subcarriers in one symbol for pilot signal transmission; and occupies a plurality of subcarriers that are interleaved with the subcarriers existing in the previous symbol in at least one other symbol for pilot signal transmission; The symbol is time division multiplexed with the symbol of the user terminal transmitting the data signal.

2. The method according to claim 1, wherein the length of each symbol is less than the length of time that the user terminal transmits the symbol of the data signal.

3. The method according to claim 1, wherein a frequency band in which a plurality of subcarriers occupied by the user terminal in the symbols overlaps with a frequency band occupied by the user terminal in a symbol for transmitting a data signal.

4. A user terminal based on single carrier frequency division multiple access, comprising: locating a plurality of subcarriers in one symbol, and occupying subcarriers occupied in a previous symbol in at least another symbol a unit of several subcarriers interleaved at a location; and

5. An uplink pilot multiplexing method based on single carrier frequency division multiple access, characterized in that it comprises the steps of:

Each user terminal occupies a plurality of subcarriers in a specified symbol for pilot signal transmission according to a pilot multiplex resource indication delivered by the network side; Pilot signal transmission is performed in at least one other symbol occupying a plurality of subcarriers that are not identical to the subcarriers occupied in the designated symbol; the symbols are time division multiplexed with the symbol of the user terminal transmitting the data signal.

The method according to claim 5, wherein each of the user terminals performs the same shift on each subcarrier in at least another symbol with each subcarrier position occupied in the designated symbol as a reference. a cyclic shift of the bit amount;

Each subcarrier determined after occupying the shift performs pilot signal transmission.

The method according to claim 5, wherein the frequency band in which the user terminal occupies a plurality of subcarriers in the respective symbols overlaps with the frequency band occupied by the user terminal in the symbol of the transmitted data signal.

8. An uplink pilot multiplexing system based on a single carrier frequency division multiple access, comprising: a network side and a user terminal side, wherein the network side comprises:

The user terminal side includes:

Means for occupying several subcarriers in a specified symbol according to a pilot multiplexing resource indication delivered by the network side, and occupying a plurality of subcarriers that are not identical to the subcarriers occupied in the specified symbol in at least one other symbol ; with

9. The system according to claim 8, wherein the unit for occupying subcarriers in each symbol in the user terminal is referenced in at least another symbol by each subcarrier position occupied in the designated symbol. Each subcarrier is cyclically shifted by the same shift amount, and each subcarrier determined after the shift is occupied.

The system according to claim 8, wherein the frequency band in which the subcarriers occupying the subcarriers in each symbol in the respective symbols are respectively located in the respective symbols and the user terminal are transmitting data. There is an overlap in the frequency bands occupied by the symbols of the signals.