CN115442195A - Doppler axis zero-insertion-expansion OTFS modulation method - Google Patents
Doppler axis zero-insertion-expansion OTFS modulation method Download PDFInfo
- Publication number
- CN115442195A CN115442195A CN202211014661.0A CN202211014661A CN115442195A CN 115442195 A CN115442195 A CN 115442195A CN 202211014661 A CN202211014661 A CN 202211014661A CN 115442195 A CN115442195 A CN 115442195A
- Authority
- CN
- China
- Prior art keywords
- doppler
- signal
- time
- domain
- delay
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
- H04L27/2639—Modulators using other transforms, e.g. discrete cosine transforms, Orthogonal Time Frequency and Space [OTFS] or hermetic transforms
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/0212—Channel estimation of impulse response
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Discrete Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
The invention discloses an OTFS (optical transmission system) modulation method based on Doppler axis zero insertion expansion. The method comprises the following steps: the method comprises the steps of preprocessing a signal at a transmitting end by means of Doppler axis zero insertion extension to obtain an extended delay-Doppler domain signal, performing inverse octave Fourier transform on the extended delay-Doppler domain signal to obtain a time-frequency domain signal, performing amplitude reduction on the time-frequency domain signal to obtain a reduced signal, performing Heisebauer transform on the reduced signal to obtain an extended time domain signal, obtaining an extended time domain output signal after the extended time domain signal passes through a delay-Doppler channel, performing sampling and Virger transform on the extended time domain output signal to obtain an extended output signal of a time-frequency domain, and performing octave Fourier transform on the extended output signal of the time-frequency domain to obtain an extended output signal of a delay-Doppler domain.
Description
Technical Field
The invention belongs to the field of wireless communication, and relates to a Doppler axis zero insertion extended OTFS modulation method.
Background
We are currently in the 5G era and are moving towards the 6G era with the ongoing development of wireless mobile communication technologies. Compared with 5G, 6G can meet a larger volume of services, and needs a faster transmission speed, and communication requirements in a higher-speed mobile scene can also occur. Wireless communication also faces new challenges in high-speed mobile scenarios, mainly the channel has high delay and high doppler characteristics, and is strongly time-varying. The currently mainly used OFDM technology is greatly affected by frequency offset due to its high requirement for synchronization, and becomes no longer robust in high mobility scenarios. Based on such a situation, orthogonal time-frequency space (OTFS) modulation is proposed.
OTFS modulation introduces a new two-dimensional dimension of the delay-doppler domain while also creating fractional-doppler problems not present in previous generations of modulation techniques. Fractional doppler is widely present in OTFS modulation and presents greater challenges to channel estimation, data transmission, and signal recovery of OTFS than the integer doppler case. The existing work deduces the relation between the inter-Doppler interference and input and output caused by the fractional Doppler, and compensates the influence of the fractional Doppler at a receiving end through means such as machine learning and the like. However, these schemes rely on known fractional doppler channel information, but do not have fractional doppler channel detection schemes, and the schemes for performing compensation at the receiving end are computationally complex. Based on the above current research situation, a feasible fractional doppler channel detection scheme is needed in OTFS modulation, and the fractional doppler problem needs to be solved fundamentally.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an OTFS (optical time shift keying) modulation method for Doppler axis zero insertion extension, which effectively solves the problem of fractional Doppler.
In order to achieve the above object, the OTFS modulation method of doppler axis zero insertion extension according to the present invention includes:
the method comprises the steps of preprocessing Doppler axis zero insertion expansion of a signal at a transmitting end to obtain an expanded delay-Doppler domain signal, carrying out inverse octave Fourier transform on the expanded delay-Doppler domain signal to obtain a time-frequency domain signal, carrying out amplitude reduction on the time-frequency domain signal to obtain a reduced signal, carrying out Heisebauer transform on the reduced signal to obtain an expanded time domain signal, carrying out octave Fourier transform on the expanded time domain signal through a delay-Doppler channel to obtain an expanded time domain output signal, carrying out sampling and Virger transform on the expanded time domain output signal to obtain an expanded output signal of a time-frequency domain, carrying out octave Fourier transform on the expanded output signal of the time-frequency domain to obtain an expanded output signal of a delay-Doppler domain, and finishing OTFS modulation of Doppler axis zero insertion expansion.
The extended delay-Doppler domain signal x E [z,l]Comprises the following steps:
wherein, p is the expansion multiple, and x [ k, l ] is the signal of the transmitting terminal.
The time-frequency domain signal X E [g,m]Comprises the following steps:
the reduced signal X' E [g,m]Comprises the following steps:
X′ E [g,m]＝pX E [g,m]。
extended time domain signal x E (t E ) Comprises the following steps:
the expanded time-domain output signal y (t) is:
the expanded output signal Y of the time-frequency domain E [g,m]Comprises the following steps:
extended output signal y in the delay-doppler domain E [z,l]Comprises the following steps:
the invention has the following beneficial effects:
during specific operation, the signal sent by the sending end is subjected to preprocessing of zero insertion expansion in the Doppler axis direction, so that a symbol plane is expanded, normal OTFS transmission and channel estimation are performed after amplitude reduction operation, doppler channel information expansion is realized, fractional Doppler is detected in the form of integer Doppler in conventional OTFS modulation at the receiving end, and fractional Doppler is converted at the sending end as much as possible, so that the influence of the fractional Doppler on OTFS transmission is weakened, and the problem of fractional Doppler is effectively solved.
Drawings
FIG. 1 is a schematic diagram of an OTFS modulation process with zero-insertion extension of a Doppler axis;
FIG. 2a is a diagram of an original signal at a transmitting end;
fig. 2b is a schematic diagram of delay-doppler domain signal spreading at the transmitting end;
FIG. 3a is a diagram of a received Doppler axis null-inserted spread signal;
FIG. 3b is a diagram of the signal after the delay-Doppler domain expansion at the receiving end;
fig. 4 is a schematic diagram of a transmitting-end delay-doppler signal under an embedded pilot design;
FIG. 5 is a diagram of a delayed Doppler signal after a receiver is extended in an embedded pilot design;
fig. 6 is a graph comparing performance improvement per unit time for different expansion factors.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
There is shown in the drawings a schematic block diagram of a disclosed embodiment in accordance with the invention. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, according to actual needs.
Referring to fig. 1, the method for modulating the doppler axis zero insertion spread OTFS according to the present invention includes the following steps:
1) Establishing a system model
The system model is based on an OTFS transmission model, is improved on the basis of the OTFS transmission model, adds preprocessing of Doppler axis zero insertion expansion to the conventional OTFS modulation process, carries out amplitude reduction on the obtained time-frequency domain signals after inverse octave Fourier transform and before Heisenberg transform, carries out subsequent operation which is the same as the conventional OTFS modulation on the expanded signals, and finally adds a step of fractional Doppler detection at a receiving end.
The specific process is as follows:
the preprocessing process of the Doppler axis zero insertion extension comprises the following steps:
obtaining a delayed-Doppler domain signal x after spreading E [z,l]Then obtaining a time-frequency domain signal X through inverse Fourier transform E [g,m]Comprises the following steps:
compared to the signal in the conventional OTFS modulation process, X E [g,m]Can be expressed as:
for the obtained time-frequency domain signal X E [g,m]Carrying out amplitude reduction to obtain a reduced signal X' E [g,m]Comprises the following steps:
X′ E [g,m]＝pX E [g,m]
reduced signal X' E [g,m]Obtaining an expanded time domain signal x through Heisenberg transformation E (t E ) Comprises the following steps:
compared with the signal in the conventional OTFS modulation process, x E (t E ) Can be expressed as:
the comparison shows that the obtained time domain signal can also be regarded as a signal obtained by performing zero insertion extension on the time domain form of the original signal in the time domain. Due to insertion of the signal in the delay-Doppler domain through the Doppler axisAfter zero expansion, its total signal duration becomes p times that of the previous signal. And from the derivation of fractional doppler it can be inferred that: total transmission time length T of signal f = pNT increase, the accuracy of unit scale of the Doppler axis 1/pNT is improved, and the time domain output signal y (t) obtained after the obtained signal passes through a delay-Doppler channel after expansion is as follows:
sampling and Virgener transforming the expanded time domain output signal Y (t) to obtain an expanded output signal Y of the time-frequency domain E [g,m]Comprises the following steps:
finally, obtaining the expanded output signal y of the delay-Doppler domain through the Fourier transform E [z,l]Comprises the following steps:
and carrying out embedded pilot frequency assisted channel estimation on the expanded output signal of the delay-Doppler domain to obtain the integer Doppler under the current condition. Since the unit scale accuracy of the doppler axis becomes high, when the doppler frequency offset of the channel is mapped to the doppler axis of the delay doppler plane, the matched doppler axis scale will also increase. For example, when p =10, let F be the doppler shift of a channel, the doppler parameter τ of the channel O F × NT is the fractional doppler one digit after the decimal point. After the OTFS modulation is subjected to Doppler zero insertion expansion operation, the scale of a Doppler axis is increased by ten times, and the precision is correspondingly improved. The channel is corresponding toDoppler parameter is tau E = F × 10NT, the channel Doppler parameter estimated at the receiving end changes from fractional Doppler to integer Doppler. The estimated Doppler scale after expansion is set as j (j is more than 0 and less than pN), the expansion multiple is reduced, and the original fractional Doppler is obtained
Fractional doppler channel estimation is accomplished.
Estimating the channel fractional Doppler, selecting the needed expansion multiple to transmit, and calculating the inter-symbol interference I in the Doppler axis direction under the current fractional Doppler condition for different expansion multiples E (k, l), namely:
and based on said intersymbol interference I E (k, l), obtaining OTFS transmission performance gain G =1/I under the current expansion multiple E (k, l) and then combining the total time T of signal transmission under the current expansion multiple E Obtaining the performance improvement W = G/T =1/[ I ] in unit time E (k,l)·T E ]。
Compared with performance improvement in unit time under different expansion factors p, the method selects the proper expansion factor, so that the generation of the fractional Doppler is inhibited at the sending end, the influence of the fractional Doppler is weakened fundamentally, and the whole OTFS transmission process is optimized.
FIG. 1 is a schematic diagram of the modulation process of the Doppler axis zero-insertion-spreading OTFS, in which signals x [ k, l ] are input into the system]Then preprocessing operation of Doppler axis zero insertion expansion is carried out on the signal, amplitude reduction is carried out on the expanded signal before Heisenberg transformation, and the expanded system output signal y is obtained through OTFS modulation of a delay-Doppler domain E [z,l]Wherein x [ k, l]The method adopts a transmitting end signal designed in an embedded pilot frequency design scheme, a randomly generated channel has unknown fractional Doppler, the transmission is carried out after zero insertion and expansion of a Doppler axis, and the original signal scale is maintained through amplitude reductionSubsequent fractional doppler detection and estimation.
Fig. 2a and fig. 2b are schematic diagrams of zero insertion and spreading of a doppler axis of a signal at a transmitting end in the present invention, where a delay-doppler domain signal is a two-dimensional signal, and after a certain spreading multiple is selected, a zero-valued symbol is inserted between every two original symbols in the direction of the doppler axis at the transmitting end.
Fig. 3a and 3b are schematic diagrams of signals after the delay-doppler domain expansion at the receiving end, and when there are multiple signals with different doppler parameters, due to the superposition between the multipath channels, the inserted null symbol area will be filled due to the shifting of the channels with different doppler parameters. Doppler parameter information of the current multiple channels can be obtained through channel estimation. Wherein, the channel existing on the integral multiple expansion multiple scale has integral Doppler parameter, and the channel existing on the non-integral multiple expansion multiple scale has fractional Doppler parameter.
And generating the delay-doppler domain signal of the transmitting end shown in fig. 4 according to the pilot design scheme assisted by the embedded pilot. After the modulation of the OTFS with zero insertion and spreading of the doppler axis, the spread received signal of the receiving end delay-doppler domain of fig. 5 is obtained, and according to the embedded pilot-assisted channel estimation scheme, the fractional doppler information of the channel can be obtained, thereby completing the detection of the fractional doppler channel.
Fig. 6 is a comparison diagram of performance improvement per unit time under different expansion factors, and the expansion factor suitable for the current channel in the current environment can be selected by comparing the performance per unit time.
Claims (8)
1. An OTFS modulation method of Doppler axis zero insertion extension is characterized by comprising the following steps:
the method comprises the steps of preprocessing Doppler axis zero insertion expansion of a signal at a transmitting end to obtain an expanded delay-Doppler domain signal, carrying out inverse octave Fourier transform on the expanded delay-Doppler domain signal to obtain a time-frequency domain signal, carrying out amplitude reduction on the time-frequency domain signal to obtain a reduced signal, carrying out Heisebauer transform on the reduced signal to obtain an expanded time domain signal, carrying out octave Fourier transform on the expanded time domain signal through a delay-Doppler channel to obtain an expanded time domain output signal, carrying out sampling and Virger transform on the expanded time domain output signal to obtain an expanded output signal of a time-frequency domain, carrying out octave Fourier transform on the expanded output signal of the time-frequency domain to obtain an expanded output signal of a delay-Doppler domain, and finishing OTFS modulation of Doppler axis zero insertion expansion.
2. The method of claim 1, wherein the extended delay-doppler domain signal x is used for OTFS modulation with zero-insertion extension of doppler axis E [z,l]Comprises the following steps:
wherein, p is the expansion multiple, and x [ k, l ] is the signal of the transmitting terminal.
3. The method of claim 2, wherein the time-frequency domain signal X is the OTFS modulation method with zero-insertion spread of doppler axis E [g,m]Comprises the following steps:
4. the method of claim 3, wherein the restored signal X 'is the Doppler axis zero-inserted spread OTFS modulation method' E [g,m]Comprises the following steps:
X′ E [g,m]＝pX E [g,m]。
5. the method of claim 4, wherein the extended time-domain signal x is the OTFS modulation method with zero-insertion extension of Doppler axis E (t E ) Is composed of：
6. The method of claim 5, wherein the extended time-domain output signal y (t) is:
7. the method of claim 6, wherein the extended output signal Y of the time-frequency domain is the OTFS modulation method with zero-insertion extension of Doppler axis E [g,m]Comprises the following steps:
Y E [g,m]＝A′ grxr (τ,v)| τ＝pT,v＝mΔf 。
8. the method of claim 7, wherein the extended output signal y in the delay-doppler domain is used as the modulation signal of OTFS E [z,l]Comprises the following steps:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211014661.0A CN115442195A (en) | 2022-08-23 | 2022-08-23 | Doppler axis zero-insertion-expansion OTFS modulation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211014661.0A CN115442195A (en) | 2022-08-23 | 2022-08-23 | Doppler axis zero-insertion-expansion OTFS modulation method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115442195A true CN115442195A (en) | 2022-12-06 |
Family
ID=84244967
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211014661.0A Pending CN115442195A (en) | 2022-08-23 | 2022-08-23 | Doppler axis zero-insertion-expansion OTFS modulation method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115442195A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116346164A (en) * | 2023-03-13 | 2023-06-27 | 南京邮电大学 | Maximum likelihood detection method for continuous parallel interference elimination in OTFS system |
-
2022
- 2022-08-23 CN CN202211014661.0A patent/CN115442195A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116346164A (en) * | 2023-03-13 | 2023-06-27 | 南京邮电大学 | Maximum likelihood detection method for continuous parallel interference elimination in OTFS system |
| CN116346164B (en) * | 2023-03-13 | 2023-11-24 | 南京邮电大学 | Maximum likelihood detection method for continuous parallel interference elimination in OTFS system |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102932289B (en) | Cyclic shifting-based method for estimating shifting number and channel response in orthogonal frequency division multiplexing (OFDM) system | |
| CN108462557B (en) | Iterative detection method for joint channel estimation in FBMC system | |
| JP2020519162A (en) | Method and apparatus for determining uplink synchronization timing deviation | |
| CN105516045A (en) | OFDM (Orthogonal Frequency-Division Multiplexing) training sequence construction method and synchronization method | |
| CN101783781A (en) | Information transmission method for lowering peak to average power ratio of OFDM system signal | |
| CN112910816B (en) | Filter bank multi-carrier timing synchronization method based on phase weighting conjugate symmetry | |
| CN115442195A (en) | Doppler axis zero-insertion-expansion OTFS modulation method | |
| CN102377726B (en) | Timing synchronization method of OFDM (Orthogonal Frequency Division Multiplexing) system | |
| CN109194594A (en) | A kind of phase noise inhibition method based on continuous carrier polymerization | |
| CN109412990B (en) | Method and device for measuring first-path arrival time difference | |
| CN103297100B (en) | A kind of doppler changing rate method of estimation for ofdm system and system | |
| CN102065035B (en) | Channel estimation method of multi-band orthogonal frequency-division multiplexing ultra-wideband system | |
| CN116016082A (en) | Time-frequency estimation method of low-orbit satellite communication system based on differential pilot frequency | |
| CN113992481B (en) | Channel estimation method assisted by surrounding pilot frequency design | |
| CN102447659B (en) | A kind of signal processing method based on single carrier frequency domain equalization, Apparatus and system | |
| CN116248444A (en) | OTFS system channel estimation method in car networking based on improved convolutional neural network | |
| CN113132276B (en) | Single carrier frequency domain equalization transmission system for remote unmanned aerial vehicle image transmission | |
| WO2017097077A1 (en) | Data processing method and apparatus | |
| CN108683624B (en) | Burst OFDM frequency offset estimation method based on interference self-cancellation technology | |
| CN104205694A (en) | Channel estimation method and receiver | |
| KR101501334B1 (en) | Method for Estimating Frequency Offset based on OFDM System and Apparatus Thereof | |
| CN107426131B (en) | Anti-frequency-deviation low-correlation search peak timing estimation method based on cyclic prefix | |
| CN107277913B (en) | timing synchronization method, device and system | |
| KR100391565B1 (en) | An Rayleigh Fading Compensation Method with Modified Sinc Interpolation | |
| CN114928520B (en) | Generalized frequency division multiplexing time-frequency synchronization method for compensating frequency offset |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |