CN1801680A - Pilot multiplex method based on interlaced FDMA and its device - Google Patents

Abstract

The invention discloses a pilot frequency multiplexing method based on interleaving frequency division multiple access, which is used to perform pilot multiplexing processing between at least two pilot symbols time-divided with user data symbols in a channel estimation cycle, including setting The subcarrier density occupied by the user during the data symbol is greater than the subcarrier density occupied by the user during each pilot symbol; the users are grouped; each user in each group staggers and occupies each other's pilot between each pilot symbol subcarrier. The present invention can reduce the interval of the pilot sub-carriers occupied by the pilot symbols in the frequency domain, thereby obtaining better interpolation processing effect.

Description

Pilot multiplexing method and device based on interleaving frequency division multiple access

technical field

The present invention relates to wireless communication technology, in particular to a pilot frequency multiplexing method and device based on interleaved frequency division multiple access (IFDMA, interleaved frequency division multiple access).

Background technique

In recent years, multi-carrier technology has become a hot technology in broadband wireless communication. The basic idea is to divide a broadband carrier into multiple sub-carriers, and transmit data in parallel on the divided sub-carriers. Usually the width of the subcarrier is smaller than the coherent bandwidth of the channel, so that on the frequency selective channel, the fading of each subcarrier is flat fading, which can reduce the crosstalk between data symbols, and does not require complex channel equalization, suitable for high speed data transmission. Multi-carrier technology usually uses frequency-domain channel estimation technology and frequency-domain equalization technology. Some single-carrier systems can also perform Fourier Transformation (FFT, Fourier Transformation) at the receiving end, so that the single-carrier system is equivalent to multiple parallel sub-carrier systems. A system composed of carriers is used for frequency domain channel estimation and frequency domain equalization processing.

Channel estimation in the frequency domain usually uses a coherent demodulation method based on auxiliary information, inserting some known pilot symbols or training sequences at certain fixed positions of the transmitted signal at the transmitting end, and using these pilot signals at the receiving end according to a certain algorithm Perform frequency domain channel estimation. The frequency-domain estimation of the channel is equivalent to the system having a time-frequency two-dimensional structure (instant domain and frequency domain), so the design of the pilot symbols used here should take into account the time-frequency two-dimensional correlation characteristics of the channel as much as possible. Among them, as long as the interval of the pilot symbols in the time and frequency directions is small enough compared with the correlation time of the channel and the channel coherence bandwidth, the channel transfer function of the position of the inserted pilot symbols can be better estimated at the receiving end, and then adopt A two-dimensional interpolation method is used to estimate the channel transfer function of all inserted pilot symbol positions. Therefore, the design of inserted pilot symbols is increasingly becoming a key issue in systems using frequency-domain channel estimation and frequency-domain equalization processing.

At present, in the uplink of the wireless communication system, the peak-to-average ratio of the transmit power is a problem that cannot be ignored, and it will directly affect the effectiveness and power consumption characteristics of the power amplifier of the user terminal. The existing interleaved frequency division multiple access (IFDMA, interleaved frequency division multiple access) technology carries out signal carrying on the time-domain waveform, so that the peak-to-average ratio of the transmission power is relatively low; at the same time, the time-frequency occupied by different users The resources are also disjoint, so that the interference between different users in the cell can be reduced. IFDMA can be realized through time-domain processing or frequency-domain processing. The IFDMA implemented in the frequency domain is called DFT-S-OFDMA. domain waveform. The difference between these two implementations lies in the processing of the transmitted data. When IFDMA is implemented using time domain processing, it realizes the comb spectrum in the frequency domain through repetition in the time domain; while IFDMA uses frequency domain processing to achieve , the comb spectrum is directly constructed according to the frequency domain features, and then processed into a time domain waveform by inverse fast Fourier transform (IFFT, Inverse Fast Fourier Transformation). The implementation process of implementing IFDMA by using the time domain processing process and the frequency domain processing process will be described respectively below.

1. Implementation process of time domain processing

Here, it is assumed that Q data symbols d _q ⁽ⁱ⁾ (d _q ⁽ⁱ⁾ can be a real number or a complex number) of a certain user i form a data block block, where each data symbol has a duration of Ts, and one of the user i The data block block can be expressed as $d^{\left(i\right)}={[d_0^{\left(i\right)},d_1^{\left(i\right)},\·\·\·,d_{Q-1}^{\left(i\right)}]}^T$ (where T represents matrix transposition), now compress the data symbols in this data block block so that it changes from data symbol duration Ts to chip duration Tc, and then repeat the data block block L times to obtain repeated processing The subsequent data symbols are:

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

$c_l^{\left(i\right)}=\frac{1}{L}\&Center\; Dot;d_{l\mathrm{mod}Q}^{\left(i\right)},$ l=0, 1, . . . , QL-1.

The data symbol sequence obtained after repeated processing in this way presents a set of comb-like spectrum shapes on the frequency axis, as shown in FIG. 1 .

Since the data blocks of each user have undergone the same processing as above, they appear as the same comb spectrum on the frequency axis. At the same time, in order to avoid mutual interference between multiple users, it is necessary to combine the comb spectrum , so that a user-specific set of phase vectors needs to be chosen here:

${\mathrm{the\; s}}_l^{\left(i\right)}=\exp \{-j\·l\·{\mathrm{\Φ}}^{\left(i\right)}\},$ l=0, . . . , QL-1, ${\mathrm{\Φ}}^{\left(i\right)}=i\&Center\; Dot;\frac{2\mathrm{\π}}{\mathrm{QL}},$ Where S represents the phase vector of the user, and Φ represents the phase rotation factor;

Multiply the obtained group of phase vectors of the user with the above obtained data symbol c _l ⁽ⁱ⁾ element by element, and finally the useful data part of the transmitted signal of the user i is obtained as:

${\mathrm{<span\; class="notranslate">\; x</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j\&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; QL</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; QL</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; .</span>$

In actual processing, it is necessary to further add guard time to reduce or eliminate the inter-symbol interference caused by channel multipath delay, where the added guard time is required to satisfy T _Δ >τ _max (where T _Δ represents the added guard time value, τ _max represents the maximum multipath delay spread of the channel); at the same time, in order to simplify the frequency domain equalization process at the receiving end, it is also necessary to choose to add a cyclic prefix (CP, cyclic prefix) to the transmitted signal symbol, that is, the end of each transmitted signal symbol A segment of symbols is copied before the starting position of the signal symbol, so that the length of the transmitted signal symbol will become T _s + T _Δ , and the receiving end needs to remove the redundancy of the CP part before processing the received signal.

Correspondingly, at the receiving end, it is necessary to separate the comb spectra of multiple users and combine the repeated data symbols; at the same time, it is also necessary to introduce a frequency domain equalizer to resist the gap between the data symbols in the data block caused by the wireless transmission process. Interfere with ISI. The maximum number of multiplexing users that can be supported by the IFDMA system implemented by the time-domain processing method will not exceed the number of repetitions L of its data blocks.

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

As shown in Figure 2, it is a schematic diagram of the implementation principle of the existing DFT-S-OFDMA: the sending end first performs discrete Fourier (DFT, Discrete Fourier Transformation) processing on the time-domain data sent, that is, performs "pre-transformation" on the pre-sent time-domain data. Encoding" operation; then perform frequency domain windowing processing on the frequency domain data processed by DFT to further reduce the peak-to-average ratio of the pre-transmitted time domain data (this process is optional); then map the frequency domain data according to the specified mapping rules To a wider frequency band, the inverse fast Fourier transform (IFFT) is finally performed on the mapped frequency domain data to obtain the corresponding time domain waveform.

The key step in this process is the mapping process of frequency domain data. If the lengths of DFT and IFFT are equal, then the mapping is one-to-one correspondence. At this time, DFT processing and IFFT processing completely cancel each other, which is equivalent to a single carrier link; and If the length of DFT is smaller than IFFT, then it needs to be processed by equal interval mapping, that is:

In order to obtain the same comb spectrum as the frequency spectrum formed by repeating the data block L times in the above-mentioned time-domain processing method (as shown in Figure 1), wherein each X[m] in the above-mentioned matrix represents the frequency domain obtained by DFT transformation Sample points, and different users are distinguished through different frequency domain subcarrier offsets, which is equivalent to user phase rotation in an IFDMA system.

The time-domain waveform processed by the above process also needs to be added to the CP operation.

Correspondingly, after the CP is removed at the receiving end, it is first necessary to perform FFT processing on the data after removing the CP, and then separate the comb spectra of different users according to the mapping rules of the sending end, and then perform IDFT after equalization in the frequency domain , to obtain the time-domain data needed for demodulation processing. Similarly, the maximum number of multiplexing users that can be supported by the IFDMA system implemented by the frequency domain processing method will not exceed L.

In the IFDMA system realized by the above-mentioned implementation, each user must occupy at least one subcarrier system (that is, a set of comb teeth), and the subcarrier system is scattered over the entire frequency band. From the perspective of frequency, the user’s signal symbol passes During actual channel transmission, different frequency fadings are experienced, so it has the effect of frequency diversity.

In an actual IFDMA system, each user needs to provide pilot symbols for channel estimation in the frequency domain to the receiver while sending uplink data. Since the transmitted signal in the IFDMA system uses time-domain waveforms to carry information, at the same time, in order to To avoid causing too high a peak-to-average ratio, it is necessary to select the way of time-division multiplexing of pilot symbols and data symbols. However, the use of pilot symbols also needs to consider the issue of efficiency. The design principle is that the resource occupancy of pilot symbols should not exceed 20% of all symbol resources (the sum of pilot symbols and data symbols); and in order to track time-varying Channel, such as when the mobile speed of the user is relatively high, when a transmission time interval (TTI, Transmission Time Interval) is 0.5ms or longer, multiple scattered pilot symbols are required in one TTI. Obviously, the pilot symbol is more than The short data symbol structure can easily meet the requirements of the above conditions: it can not only ensure a low occupancy rate of symbol resources, but also track time-varying channels. At present, in the existing technology, for the 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. Figure 3 shows a typical TTI structure using half-symbol pilot Schematic diagram, where two short pilot symbols are included in the TTI and are scattered among the data symbols in a TTI.

Taking the TTI structure shown in Figure 3 as an example, such a TTI structure meets the design requirements, but in practical applications, especially in the multiple access mode in the IFDMA system, the half-symbol pilot mode brings other problems . In digital signal processing, the length of time determines the granularity of digital frequencies in the frequency domain, and the unequal lengths of pilot symbols and data symbols will cause the frequency components of the user's pilot symbols and data symbols to be inconsistent in the frequency domain. correspond. That is to say, after being transmitted through the wireless channel, the pilot symbols cannot 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 are explained in detail below:

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

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; mn</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

X[m] represents the frequency domain performance, that is, each subcarrier;

$x\left(\mathrm{no}\right)\frac{1}{N}\underset{m=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left[m\right]\exp \left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{\mathrm{mn}}{N}\right),\mathrm{no}=\mathrm{0,1},\&Center\; Dot;\&Center\; Dot;\&CenterDot;,N-1$ x(n) represents the time domain waveform;

According to the above IFDMA technical description, in the time-division multiplexing TTI structure of half-symbol pilot and data symbols, data symbols and pilot symbols have different phase rotation factors: the phase rotation factor of the data part of user i is $\mathrm{\&Phi;}\left(i\right)=i\&CenterDot;\frac{2\mathrm{\&pi;}}{\mathrm{QL}},$ i=0, 1,..., L-1, in order to support the same number of users, the phase rotation factor of the half symbol length pilot part is:

${\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

All of the above assume that Q and L are even numbers, then write out the repeated part of the data symbol and the pilot symbol separately, and then obtain the transmitted signal symbol of the data part as:

${{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j\&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</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>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; ,</span>$

And the transmitted signal symbol of obtaining the pilot part is:

${{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; ,</span>$

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

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; QL</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; mn</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; QL</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span>$

m=0, 1,..., QL-1, i=0, 1,..., L-1

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\frac{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; mn</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\frac{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span>$

i＝0，1，...，L-1m=0,1,...,

i=0,1,...,L-1

Obviously, as shown in the above formula, the frequency component contained in the pilot part is half of the data part, and since the length of the pilot symbol is exactly half of the data symbol, the interval of the frequency component of the pilot symbol is exactly the frequency of the data symbol Twice the interval of the components, that is, the density of the subcarriers is different, as shown in FIG. 4 .

In order to perform effective frequency domain equalization processing at the receiving end, it is necessary to obtain channel information with the same frequency granularity as that of the data symbols, for which frequency domain interpolation processing is performed. The principle of interpolating the channel estimation results in the frequency domain is as follows: assuming that the interval between two frequency points is within the coherent bandwidth of the channel, several frequency points in the middle are obtained by using their 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:

First, the received pilot signal symbol x _p ⁽ⁱ⁾ is transformed into the frequency domain by FFT, and the transformation length is

Using the known transmitted pilot signal for frequency domain channel estimation, we get frequency points;

Then IFFT transforms the channel obtained by channel estimation in the frequency domain into the time domain, and the transformation length is

And zero-fill the transformed time-domain signal, and do the FFT transformation of the QL point:

${\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; QL</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}}_{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; mn</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; QL</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}}_{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20051009258600213.png,A20051009258600221.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; QL</span>}}<span\; class="notranslate">\; )</span>$

m=0, 1,..., QL-1; i=0, 1,..., L-1

In this way, a channel frequency domain response with the same frequency granularity as the data part is obtained;

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

Among them, in a multi-user IFDMA system, when the interval between the subcarriers occupied by the pilot symbols of a user is relatively large, the effect of frequency domain interpolation processing is not ideal; and if within a channel estimation period, the pilot symbols occupy Only when the average frequency domain spacing of the subcarriers is relatively small can a better interpolation processing effect be obtained.

Contents of the invention

The technical problem to be solved by the present invention is to provide a pilot multiplexing method based on interleaving frequency division multiple access and its device, so as to reduce the interval of pilot subcarriers occupied by pilot symbols in the frequency domain, thereby obtaining better The interpolation processing effect.

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

A pilot multiplexing method based on interleaving frequency division multiple access, used to perform pilot multiplexing processing between at least two pilot symbols time-divided with user data symbols in a channel estimation period, comprising steps:

A. It is set that the subcarrier density occupied by the user during the data symbol is greater than the subcarrier density occupied by the user during each pilot symbol;

B. Group users into groups;

C. Each user in each group staggers and occupies each other's pilot sub-carriers between pilot symbols.

Preferably, in the step A, the density of data subcarriers is greater than that of pilot subcarriers by setting the time length of pilot symbols to be smaller than the time length of data symbols.

Preferably, in the step A, the density of data subcarriers is greater than that of pilot subcarriers by selecting some of the data subcarriers as pilot subcarriers.

Preferably, in the step B, the positional relationship of data subcarriers among users in each group of users is adjacent; or the positional relationship of data subcarriers among users is random.

Preferably, the implementation process of the step C specifically includes:

C1. Each user in each group alternately occupies each pilot subcarrier in the frequency domain of the first pilot symbol in accordance with the original sequence; and

C2. In the frequency domain of the next pilot symbol, alternately occupy each pilot subcarrier in the frequency domain after exchanging the sequence of each user in the group.

Preferably, users in each group alternately occupy pilot subcarriers that overlap with their own data subcarriers in the frequency domain of each pilot symbol.

Preferably, in the step C, the proportions of pilot subcarriers occupied by each user in each group are the same.

A pilot multiplexing device based on interleaved frequency division multiple access, which is used to perform pilot multiplexing processing between at least two pilot symbols time-divided with user data symbols in a channel estimation cycle, including:

The setting unit is configured to set the subcarrier density occupied by the user during the data symbol period to be greater than the subcarrier density occupied by the user during each pilot symbol period;

a grouping unit, configured to group users;

The multiplexing unit is configured to alternately occupy each other's pilot subcarriers among the pilot symbols set by the setting unit for each user in each group divided by the grouping unit.

Preferably, the multiplexing unit specifically includes:

Pilot subcarriers alternately occupy subunits, which are used for each user in each group to alternately occupy each pilot subcarrier in the frequency domain of the first pilot symbol in accordance with the original sequence;

The user sequence switching subunit is used to switch the sequence of each user in the group in the frequency domain of the next pilot symbol; after the sequence of each user in the group is switched by the pilot subcarrier alternate occupancy subunit, Each pilot subcarrier is alternately occupied in the frequency domain of the next pilot symbol.

A pilot multiplexing method based on interleaving frequency division multiple access, used to perform pilot multiplexing processing between at least two pilot symbols time-divided with user data symbols in a channel estimation period, comprising steps:

a. Set the data subcarrier density occupied by the user in the data symbol frequency domain to be greater than the pilot subcarrier density occupied by the user in each pilot symbol frequency domain;

b. select a pilot symbol;

c. determining the pilot subcarriers occupied by each user in the frequency domain of the selected pilot symbols;

d. On each other pilot symbol frequency domain, the pilot subcarriers occupied by each user determined on the selected pilot symbol frequency domain are respectively subjected to cyclic shift processing with the same shift amount; for different In the frequency domain of the pilot symbols, the shifting amounts selected for shifting the pilot subcarriers occupied by each user are different from each other.

A pilot multiplexing device based on interleaved frequency division multiple access, which is used to perform pilot multiplexing processing between at least two pilot symbols time-divided with user data symbols in a channel estimation cycle, including:

A setting unit, configured to set the data subcarrier density occupied by the user in the data symbol frequency domain to be greater than the pilot subcarrier density occupied by the user in each pilot symbol frequency domain;

a selection unit, configured to select a pilot symbol;

a pilot subcarrier determination unit, configured to determine the pilot subcarriers occupied by each user in the frequency domain of the pilot symbols selected by the selection unit;

The shift processing unit is configured to, for each of the other pilot subcarriers, respectively divide the pilot subcarriers occupied by the users determined by the pilot subcarrier determination unit in the frequency domain of the pilot symbols selected by the selection unit Perform cyclic shift processing with the same shift amount; for different pilot subcarriers, the shift amounts of the pilot subcarriers occupied by each user are different from each other.

The beneficial effect that the present invention can reach is as follows:

In the present invention, the subcarrier density occupied by the user during the data symbol is greater than the subcarrier density occupied by the user during each pilot symbol; the users are grouped; each user in each group occupies each pilot symbol alternately Pilot subcarriers of each other; thus it can be realized that in the interleaved frequency division multiple access IFDMA system, the average interval of pilot subcarriers occupied by multiple users in the pilot symbol frequency domain is reduced, that is, it can ensure that each pilot subcarrier There is relatively small spacing in the frequency domain of the pilot symbols, thereby improving the effectiveness of channel estimation and interpolation processing in the frequency domain.

Description of drawings

FIG. 1 is a schematic diagram of a comb-like spectrum shape presented on the frequency axis by a data symbol sequence obtained after repeated processing of a data block;

FIG. 2 is a schematic diagram of the implementation principle of the existing DFT-S-OFDMA;

FIG. 3 is a schematic diagram of a typical TTI structure using half-symbol pilots;

FIG. 4 is a schematic diagram of the relationship between the frequency component interval of the data symbol and the frequency component interval of the pilot symbol after the half-symbol pilot is used;

Fig. 5 is the main realization principle flowchart of the pilot multiplexing method based on IFDMA of the present invention;

Fig. 6 is according to the principle of the method of the present invention, the schematic diagram of the multiplexing mode of the first example of data symbols and pilot symbols given by taking 4 users as an example;

7 is a schematic diagram of a second example multiplexing mode of data symbols and pilot symbols given by taking 4 users as an example according to the principle of the method of the present invention;

Fig. 8 is a schematic diagram of a third example multiplexing mode of data symbols and pilot symbols given by taking 4 users as an example according to the principle of the method of the present invention;

Fig. 9 is a schematic diagram of the multiplexing mode of the first example 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;

FIG. 10 is a structural block diagram of the main components of the IFDMA-based pilot multiplexing device of the present invention;

FIG. 11 is a flow chart of the main implementation principles of another IFDMA-based pilot multiplexing method of the present invention;

Fig. 12 is a schematic diagram of a second example multiplexing mode 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;

FIG. 13 is a structural block diagram of main components of another IFDMA-based pilot multiplexing device according to the present invention.

Detailed ways

The design purpose of the present invention is to provide a way for multiple users to multiplex the frequency domain of the pilot symbols, so that the interval between the pilot subcarriers on the frequency domain of the pilot symbols becomes smaller to obtain better interpolation processing effect.

The main realization principle and specific implementation manners of the present invention will be described in detail below with reference to each accompanying drawing.

Please refer to FIG. 5, which is a flow chart of the main implementation principles of the IFDMA-based pilot multiplexing method of the present invention, which is mainly used for at least two and user data symbols in a channel estimation period (such as one TTI or several TTIs) The main implementation process of pilot multiplexing processing between time-division pilot symbols is as follows:

Step S10, setting the subcarrier density occupied by the user during the data symbol is greater than the subcarrier density occupied by the user during each pilot symbol; which can be realized by setting the time length of the pilot symbol to be less than the time length of the data symbol The density of data subcarriers is greater than that of pilot subcarriers; the density of data subcarriers greater than that of pilot subcarriers can also be achieved by selecting some subcarriers from data subcarriers as pilot subcarriers.

In step S20, the users are grouped; the data subcarrier position relationship between users in each group of users can be adjacent; the data subcarrier position relationship between users can also be random.

In step S30, each user in each group alternately occupies each other's pilot subcarriers among pilot symbols. Its specific implementation includes:

Each user in each group alternately occupies each pilot subcarrier in the frequency domain of the first pilot symbol according to the original sequence; and

In the frequency domain of the next pilot symbol, after the order of each user in the group is exchanged, each pilot subcarrier is alternately occupied in the frequency domain.

Each user in each group alternately occupies a pilot subcarrier that has frequency spectrum overlap with its own data subcarrier in the frequency domain of each pilot symbol.

Each user in each group occupies the same proportion of pilot subcarriers.

According to the IFDMA technical characteristics described in the above-mentioned prior art, assuming that the phase rotation factor of the kth user data symbol is Φ(k), then the phase rotation factor of the pilot symbol of one and a half symbol lengths of the user is just 2Φ(i ),one of them Where L represents the number of repetitions of the data block, Indicates rounding down.

Fig. 6 has provided according to the principle of the method of the present invention, take 4 users as an example and give the schematic diagram of the multiplexing mode of the first example of data symbols and pilot symbols, that is, when L=4; k=0,1,2,3 , according to the relationship of the above formula, i=0, 2, 1, 3 are correspondingly obtained, that is to say, when there are 4 users performing interleaving frequency division multiplexing, the phase offsets of these 4 users in the data part are respectively 0 , 1, 2, 3, and the phase offsets in the pilot part are 0, 2, 1, 3 respectively, and the phase rotation is performed with twice the step size, which is equivalent to every two comb teeth in the data part Adjacent users are divided into a group, and the two users alternately occupy pilot subcarriers that overlap with their own data subcarriers. That is to say, the order of user multiplexing in the data is 0, 1, 2, 3, while the order of user multiplexing in the pilot is 0, 2, 1, 3.

即当L＝4；k＝0，1，2，3时，按照上述公式对应得到j＝2，0，3，1，也就是说在第二个导频符号中，这4个用户的相位偏移分别是2，0，3，1，并且是以两倍的步长进行相位旋转，相当于数据部分中每两个梳齿相邻的用户分为一组，在第一个导频符号中交替占用和自己的数据子载波有频谱重叠的导频子载波，在第二个导频符号中同组的这两个用户交换顺序后，再交替占用和自己的数据子载波有频谱重叠的导频子载波。也就是说，数据中用户复用的顺序是0，1，2，3，而第一个导频中用户复用的顺序是0，2，1，3，第二个导频中用户复用的顺序是1，3，0，2。具体如图7所示，为按照本发明方法原理以4个用户为例给出的数据符号和导频符号的第二实例复用方式示意图；It can be seen that the IFDMA system implemented by the method of the present invention is generally more suitable for users moving at high speed. In order to better track the time-varying channel of users moving at high speed, usually in a channel estimation period, a plurality of time-dispersed pilot symbols will be used. Based on this principle, the present invention also proposes that the above-mentioned kth user The phase rotation factor of the pilot symbol of the second half-symbol length of is set to 2Φ(j), where

That is, when L=4; k=0, 1, 2, 3, j=2, 0, 3, 1 can be correspondingly obtained according to the above formula, that is to say, in the second pilot symbol, the phases of these 4 users The offsets are 2, 0, 3, 1, respectively, and the phase rotation is performed with twice the step size, which is equivalent to grouping every two comb-tooth-adjacent users in the data part. In the first pilot symbol Alternately occupy the pilot subcarriers that have spectrum overlap with their own data subcarriers, and alternately occupy the pilot subcarriers that have spectrum overlap with their own data subcarriers after the two users in the same group exchange their order in the second pilot symbol. Pilot subcarriers. That is to say, the order of user multiplexing in the data is 0, 1, 2, 3, while the order of user multiplexing in the first pilot is 0, 2, 1, 3, and the order of user multiplexing in the second pilot The order is 1, 3, 0, 2. Specifically, as shown in Figure 7, it is a schematic diagram of a second example multiplexing mode of data symbols and pilot symbols given by taking 4 users as an example according to the principle of the method of the present invention;

As shown in Figure 7, in such a pilot multiplexing mode, the subcarriers where the two pilot symbols of the same user are located in a channel estimation period correspond to the data subcarriers, showing an interleaved state, which is actually equivalent to reducing The subcarrier spacing of the pilot symbols in the frequency domain is improved, so a better interpolation processing effect in the frequency domain can be obtained.

Of course, when the IFDMA system configures more than two pilots for the users, it is also possible to use among the multiple pilots the pilot sub-carrier mode that users of the same group occupy alternately and their own data sub-carriers have spectrum overlapping.

Of course, it is not necessarily necessary to divide users adjacent to each other in the frequency domain into one group. Any two users can be divided into groups, and users in the same group alternately occupy each other's pilots among multiple pilots. carrier. The pilot sub-carrier does not necessarily overlap with the user's data sub-carrier. As shown in Figure 8, it is a schematic diagram of the third example multiplexing mode of data symbols and pilot symbols given by taking 4 users as an example according to the principle of the method of the present invention; as shown in this figure, users 0 and 2 are divided into one group, and group users 1 and 3 into one.

In addition, more than 2 users can also be selected for division and grouping, and users in the same group stagger among multiple pilots to occupy each other's pilot subcarriers according to specified rules. FIG. 9 is a schematic diagram of a first example multiplexing mode 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.

Correspondingly, relative to the method proposed above, the present invention also proposes an IFDMA-based pilot multiplexing device, please refer to FIG. 10 , which is a block diagram of the main components of the IFDMA-based pilot multiplexing device of the present invention ; It mainly includes:

The setting unit 10 is configured to set the subcarrier density occupied by the user during the data symbol period to be greater than the subcarrier density occupied by the user during each pilot symbol;

A grouping unit 20, configured to group users into groups;

The multiplexing unit 30 is configured to interleave and occupy each other's pilot subcarriers among the pilot symbols set by the setting unit 10 for each user in each group divided by the grouping unit 20 .

Wherein the multiplexing unit 30 specifically includes:

Pilot subcarriers alternately occupy subunits, which are used for each user in each group to alternately occupy each pilot subcarrier in the frequency domain of the first pilot symbol in accordance with the original sequence;

The user sequence switching subunit is used to switch the sequence of each user in the group in the frequency domain of the next pilot symbol; after the sequence of each user in the group is switched by the pilot subcarrier alternate occupancy subunit, Each pilot subcarrier is alternately occupied in the frequency domain of the next pilot symbol.

Correspondingly, the present invention also proposes a pilot multiplexing method based on IFDMA. As shown in FIG. The pilot multiplexing process is performed between at least two pilot symbols time-divided with the user data symbols in the estimation period, and the main implementation process is as follows:

Step S100, setting the data subcarrier density occupied by the user in the data symbol frequency domain is greater than the pilot subcarrier density occupied by the user in each pilot symbol frequency domain;

Step S110, selecting a pilot symbol among the pilot symbols after the above setting process; determining the pilot subcarriers occupied by each user in the frequency domain of the selected pilot symbol;

Step S120, on each of the other pilot symbol frequency domains, the pilot subcarriers occupied by each user determined on the selected pilot symbol frequency domain are respectively subjected to cyclic shift processing with the same shift amount; for In different pilot symbol frequency domains, the shift amounts selected when performing shift processing on the pilot subcarriers occupied by each user are different from each other.

That is, preferably, all users who simultaneously transmit data symbols in parallel can also be regarded as a group, and the users in the group use the same frequency hopping method to interleave between multiple pilots to occupy all pilot subcarriers, As shown in Figure 12, it is a schematic diagram of the second example multiplexing mode 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:

Among them, the pilot subcarrier position occupied by each user in pilot 2 is a cyclic shift of the pilot subcarrier position in pilot 1, and the pilot subcarrier shifts of different users are the same, and each user in pilot 3 The position of the occupied pilot subcarrier is another cyclic shift of the position of each pilot subcarrier in pilot 1. After multiplexing in this way, the pilot subcarriers of each user in the three pilots In the frequency domain, there is a smaller subcarrier spacing.

Correspondingly aiming at another method proposed above, the present invention proposes a pilot multiplexing device based on IFDMA, as shown in FIG. 13 , which mainly includes:

The setting unit 100 is used to set the data subcarrier density occupied by the user in the data symbol frequency domain to be greater than the pilot subcarrier density occupied by the user in each pilot symbol frequency domain;

A selecting unit 110, configured to select a pilot symbol among the pilot symbols set and processed by the setting unit 100;

A pilot subcarrier determining unit 120, configured to determine the pilot subcarriers occupied by each user in the frequency domain of the pilot symbols selected by the selecting unit 110;

The shift processing unit 130 is configured to, for each of the other pilot subcarriers, convert the pilot subcarriers occupied by each user determined by the pilot subcarrier determination unit 120 in the frequency domain of the pilot symbols selected by the selection unit 110 The cyclic shift processing of the same shift amount is performed respectively; for different pilot subcarriers, the shift amounts of the pilot subcarriers occupied by each user are different from each other.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (11)

1. A pilot multiplexing method based on interleaved frequency division multiple access, used to carry out pilot multiplexing processing between at least two pilot symbols time-divided with user data symbols in a channel estimation period, comprising steps: A. It is set that the subcarrier density occupied by the user during the data symbol is greater than the subcarrier density occupied by the user during each pilot symbol; B. Group users into groups; C. Each user in each group staggers and occupies each other's pilot sub-carriers between pilot symbols. 2. The method according to claim 1, wherein in said step A, the time length of the pilot symbol is set to be less than the time length of the data symbol to realize that the data subcarrier density is greater than the pilot subcarrier density of. 3. The method according to claim 1, wherein in the step A, the density of data subcarriers is greater than the density of pilot subcarriers by selecting some subcarriers from the data subcarriers as pilot subcarriers. 4. The method according to claim 1, characterized in that, in the step B, the data subcarrier position relationship between each user in each group of users is adjacent; or The data subcarrier position relationship between users is random. 5. The method according to claim 1, characterized in that, the implementation process of the step C specifically includes: C1. Each user in each group alternately occupies each pilot subcarrier in the frequency domain of the first pilot symbol in accordance with the original sequence; and C2. In the frequency domain of the next pilot symbol, alternately occupy each pilot subcarrier in the frequency domain after exchanging the sequence of each user in the group. 6. The method according to claim 1 or 5, characterized in that each user in each group alternately occupies a pilot with spectrum overlap with its own data subcarrier in the frequency domain of each pilot symbol subcarrier. 7. The method according to claim 1 or 5, characterized in that in the step C, the proportions of pilot subcarriers occupied by the users in each group are the same. 8. A pilot multiplexing device based on interleaved frequency division multiple access, which is used to perform pilot multiplexing processing between at least two pilot symbols time-divided with user data symbols in a channel estimation cycle, including: The setting unit is configured to set the subcarrier density occupied by the user during the data symbol period to be greater than the subcarrier density occupied by the user during each pilot symbol period; a grouping unit, configured to group users; The multiplexing unit is configured to alternately occupy each other's pilot subcarriers among the pilot symbols set by the setting unit for each user in each group divided by the grouping unit. 9. The method according to claim 8, wherein the multiplexing unit specifically comprises: Pilot subcarriers alternately occupy subunits, which are used for each user in each group to alternately occupy each pilot subcarrier in the frequency domain of the first pilot symbol in accordance with the original sequence; The user sequence switching subunit is used to switch the sequence of each user in the group in the frequency domain of the next pilot symbol; after the sequence of each user in the group is switched by the pilot subcarrier alternate occupancy subunit, Each pilot subcarrier is alternately occupied in the frequency domain of the next pilot symbol. 10. A pilot multiplexing method based on interleaved frequency division multiple access, used to perform pilot multiplexing processing between at least two pilot symbols time-divided with user data symbols in a channel estimation period, comprising steps: a. Set the data subcarrier density occupied by the user in the data symbol frequency domain to be greater than the pilot subcarrier density occupied by the user in each pilot symbol frequency domain; b. select a pilot symbol; c. determining the pilot subcarriers occupied by each user in the frequency domain of the selected pilot symbols; d. On each other pilot symbol frequency domain, the pilot subcarriers occupied by each user determined on the selected pilot symbol frequency domain are respectively subjected to cyclic shift processing with the same shift amount; for different In the frequency domain of the pilot symbols, the shifting amounts selected for shifting the pilot subcarriers occupied by each user are different from each other. 11. A pilot multiplexing device based on interleaved frequency division multiple access, which is used to perform pilot multiplexing processing between at least two pilot symbols that are time-divided with user data symbols within a channel estimation cycle, including: A setting unit, configured to set the data subcarrier density occupied by the user in the data symbol frequency domain to be greater than the pilot subcarrier density occupied by the user in each pilot symbol frequency domain; a selection unit, configured to select a pilot symbol; a pilot subcarrier determination unit, configured to determine the pilot subcarriers occupied by each user in the frequency domain of the pilot symbols selected by the selection unit; The shift processing unit is configured to, for each of the other pilot subcarriers, respectively divide the pilot subcarriers occupied by the users determined by the pilot subcarrier determination unit in the frequency domain of the pilot symbols selected by the selection unit Perform cyclic shift processing with the same shift amount; for different pilot subcarriers, the shift amounts of the pilot subcarriers occupied by each user are different from each other.

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