A frequency offset synchronization method and system for an ultra-high-speed MESH wireless network

Abstract

The application discloses a frequency offset synchronization method and system of an ultra-high-speed MESH wireless network, relates to the technical field of wireless communication, and generates N primary synchronization signal (PSS) sequences at a sending end, wherein each PSS sequence is preset with a different frequency offset value; the sending end sends the N PSS sequences to a receiving end through a wireless channel, and the sending mode comprises sending after orthogonal code coding or sending on different frequency domain resources; after receiving the signals, the receiving end detects the N PSS sequences according to the sending mode, and the receiving end infers a frequency offset estimation value based on the detected PSS sequence result; the receiving end applies the frequency offset estimation value to perform frequency offset pre-correction processing on the received signals, and then performs frequency offset fine correction through a secondary synchronization signal (SSS), thereby completing synchronization. The application adopts a multi-PSS sequence frequency offset coding technology, and realizes direct identification and accurate correction of the frequency offset direction through presetting of the frequency offset at the sending end and intelligent detection at the receiving end.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a frequency offset synchronization method and system for an ultra-high-speed MESH (Wireless Mesh Network) wireless network. Background Technology

[0002] In 4G / 5G public networks, base stations are located in fixed positions, and terminal movement speed is relatively limited. This network architecture can achieve effective frequency correction through conventional frequency offset compensation and frequency tracking algorithms. Since the relative motion patterns between base stations and terminals are relatively simple, Doppler frequency shift can be handled through predefined compensation mechanisms.

[0003] In NTN (Non-Terrestrial Network) satellite communications, although satellites travel at speeds up to 8 km / s, their orbits are fixed and precisely predictable. This determinism allows the system to pre-correct transmission and reception frequencies by calculating relative velocities, effectively overcoming the Doppler effect. However, in MESH wireless networks, all nodes may be in a high-speed moving state, and the relative positions and velocities between nodes are constantly changing and unpredictable. This dynamic topology makes it impossible to use frequency offset compensation methods with fixed base stations, impossible to achieve pre-correction through orbit prediction, and the Doppler frequency offset changes rapidly over time with uncertain direction.

[0004] Current wireless networks using OFDM (Orthogonal Frequency Division Multiplexing) technology attempt to address Doppler frequency offset by increasing subcarrier width. However, this method has significant drawbacks, such as reduced frequency diversity due to increased subcarrier width, decreased system spectral efficiency, and inability to meet the requirements of extreme high-speed scenarios. Summary of the Invention

[0005] In view of this, in order to solve the synchronization problem of MESH wireless networks in ultra-high-speed mobile environments, the present invention aims to provide a frequency offset synchronization method and system for ultra-high-speed MESH wireless networks. It adopts multi-PSS (Primary Synchronization Signal) sequence frequency offset coding technology, and realizes direct identification and accurate correction of frequency offset direction by preset frequency offset at the transmitting end and intelligent detection at the receiving end.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a frequency offset synchronization method for an ultra-high-speed MESH wireless network, comprising the following steps:

[0008] The transmitting end generates N master synchronization signal PSS sequences, each PSS sequence having a different preset frequency offset value;

[0009] The transmitter sends N PSS sequences to the receiver via a wireless channel. The transmission methods include transmitting after orthogonal code encoding or transmitting on different frequency domain resources.

[0010] After receiving the signal, the receiving end detects the N PSS sequences according to the transmission method, and infers the frequency offset prediction value based on the detected PSS sequence results.

[0011] The receiving end applies the frequency offset pre-estimated value to perform frequency offset pre-correction processing on the received signal, and then performs fine frequency offset correction through the secondary synchronization signal SSS (Secondary Synchronization Signal) to complete synchronization.

[0012] As a further aspect of the present invention, when the transmitting end generates N master synchronization signal PSS sequences, the frequency offset values ​​of the N PSS sequences are symmetrically distributed, including positive frequency offset, zero frequency offset and negative frequency offset, and the frequency offset interval is Δf; where N is an integer greater than 1 and less than or equal to 9, and the frequency offset interval Δf is dynamically optimized according to the subcarrier interval and the operating frequency.

[0013] As a further embodiment of the present invention, the transmitting end sends N PSS sequences at a time, and the N PSS sequences are encoded with orthogonal codes and then sent to the receiving end, or sent to different frequency domain resources.

[0014] As a further embodiment of the present invention, when the number of the N PSS sequences is 3, the frequency offset interval Δf is 4.5kHz, the allowable frequency offset is 13.5kHz, and the corresponding maximum speed is 2700m / s.

[0015] As a further aspect of the present invention, after receiving the signal, when the receiving end detects the N PSS sequences according to the transmission method, if the transmission method is orthogonal code encoding, the received orthogonally encoded PSS sequences are processed by orthogonal code before PSS sequence detection is performed; if the transmission method is transmission on different frequency domain resources, different PSS sequences are detected on multiple frequency domain resources respectively.

[0016] As a further aspect of the present invention, when the transmitting end transmits N PSS sequences on different frequency domain resources, the frequency domain resource allocation method is as follows:

[0017] Each PSS sequence occupies an independent frequency domain resource block, and the resource block interval is set based on the frequency offset value Δf to ensure minimal interference between sequences.

[0018] As a further aspect of the present invention, when the transmitting end uses orthogonal code encoding to transmit N PSS sequences, the orthogonal code is Walsh code, and the encoded sequences are multiplexed and transmitted on the same frequency domain resources.

[0019] As a further aspect of the present invention, when the receiving end infers the frequency offset prediction value based on the detected PSS sequence result, it selects the optimal value from multiple PSS detection results and inversely derives the frequency offset based on the PSS sequence. The received data frequency domain conversion includes:

[0020] When there is no frequency offset, the receiver uses PSS1 / PSS2 / PSS3 to perform correlation calculations with the PSS data at the center frequency point. PSS2 has the highest correlation peak, and the frequency offset is calculated using the received PSS and SSS data.

[0021] When the frequency offset is less than the preset threshold, the receiver uses PSS1 / PSS2 / PSS3 to perform correlation calculation with the PSS data at the center frequency point. The correlation peak of PSS2 is relatively high, and the frequency offset is calculated using the received PSS and SSS data.

[0022] When the frequency offset is greater than the preset threshold, the receiver uses PSS1 / PSS2 / PSS3 to perform correlation calculation with the PSS data at the center frequency point. The correlation peak of PSS3 is relatively high, and the frequency offset Δf2 is calculated using the received PSS and SSS data. The final frequency offset is the frequency offset Δf of PSS3 and PSS2 plus the frequency offset Δf2 calculated by PSS / SSS.

[0023] As a further aspect of the present invention, the frequency offset pre-correction processing includes frequency domain rotation or phase compensation of the received signal, and the pre-corrected signal is then subjected to SSS detection to achieve fine frequency offset correction.

[0024] As a further aspect of the present invention, the frequency offset synchronization method of the ultra-high-speed MESH wireless network is applicable to OFDM systems with a subcarrier spacing of 30kHz and an operating frequency of 1.5GHz, and supports a maximum mobile speed of 2700m / s; wherein, the allowable range of frequency offset pre-estimation is extended to 13.5kHz, corresponding to a Doppler frequency offset tolerance that is three times that of the traditional method.

[0025] Secondly, the present invention also provides a frequency offset synchronization system for an ultra-high-speed MESH wireless network, comprising:

[0026] The transmitting device is configured to generate N PSS sequences with different preset frequency offset values ​​and transmit the N PSS sequences through a wireless channel;

[0027] The receiving device is configured to receive the PSS sequence, detect N PSS sequences, infer a frequency offset prediction value based on the detected PSS sequence results, and perform frequency offset correction processing on the received signal.

[0028] The transmitting and receiving devices constitute a MESH network node, supporting synchronization in ultra-high-speed mobile environments.

[0029] As a further aspect of the present invention, the transmitting device includes:

[0030] The sequence generation module is used to generate N PSS sequences, each sequence having a different preset frequency offset value, the frequency offset values ​​being symmetrically distributed and spaced by Δf.

[0031] The transmission processing module is configured to encode the PSS sequence using orthogonal codes or transmit it on different frequency domain resources;

[0032] The radio frequency (RF) transmission module is used to transmit the processed signal to the wireless channel via an antenna.

[0033] As a further embodiment of the present invention, the transmission processing module includes an orthogonal coding unit and a resource mapping unit;

[0034] The orthogonal coding unit uses Wash code to encode N PSS sequences;

[0035] The resource mapping unit maps the encoded sequence onto frequency domain resources, and the frequency offset interval Δf is dynamically optimized based on the subcarrier interval and the operating frequency.

[0036] As a further aspect of the present invention, the receiving device includes:

[0037] The signal receiving module is configured to receive wireless signals via an antenna and perform down-conversion processing.

[0038] The frequency domain conversion module is used to convert time-domain signals into frequency-domain signals;

[0039] The PSS detection module is configured to detect the correlation peaks of N PSS sequences in the frequency domain.

[0040] The frequency offset estimation module infers the frequency offset prediction value based on the PSS sequence with the highest correlation peak.

[0041] The correction processing module is used to perform frequency offset pre-correction and fine correction on the received signal.

[0042] As a further embodiment of the present invention, the frequency offset synchronization system of the ultra-high-speed MESH wireless network supports OFDM modulation, with a subcarrier spacing of 15-120kHz and an operating frequency band of 0.5-6GHz; the system supports a maximum Doppler frequency offset of 13.5kHz, corresponding to a moving speed of 2700m / s.

[0043] Compared with existing technologies, the frequency offset synchronization method and system for ultra-high-speed MESH wireless networks provided by this invention, based on multi-PSS sequence frequency offset coding and intelligent detection mechanism, effectively solves the synchronization ambiguity problem caused by Doppler frequency offset, significantly improves the system performance in extreme scenarios, and has the following beneficial effects:

[0044] 1. The frequency offset synchronization method and system for ultra-high-speed MESH wireless networks of the present invention solves the ambiguity problem. In traditional synchronization methods, when the Doppler frequency offset exceeds half a subcarrier interval, integer multiple frequency offset ambiguity occurs, leading to synchronization failure. The present invention, however, directly indicates the frequency offset direction through multiple PSS sequences with different frequency offsets, fundamentally eliminating ambiguity. Specifically, the transmitting end generates N PSS sequences, pre-set with positive, zero, and negative frequency offsets respectively. The receiving end, by detecting the correlation peaks of these sequences, can clearly determine the frequency offset direction, avoiding misjudgment and effectively solving the ambiguity problem.

[0045] 2. The frequency offset synchronization method and system for ultra-high-speed MESH wireless networks of the present invention are also applicable to extreme scenarios, particularly suitable for unconventional mobile communication scenarios with Doppler frequency ranges such as satellite communication and ultra-high-speed mobile communication, breaking through speed limitations. For example, by using three PSS sequences, the maximum allowable frequency offset can be extended to 13.5kHz, corresponding to a speed of 2700m / s, close to Mach 8, improving speed tolerance by 3 times. This enables MESH networks to support high-speed mobile applications such as military communications like hypersonic UAV formations, low-Earth orbit satellite networks, and emergency communications, expanding the boundaries of wireless communication.

[0046] 3. In this invention, the positions and relative velocities of MESH network nodes change dynamically. By combining frequency offset pre-estimation and fine correction, the system's adaptability to dynamic topologies is improved. The receiver first performs frequency offset pre-correction, then performs fine correction via SSS, forming a two-stage correction mechanism that reduces synchronization time and improves accuracy. The PSS sequence in this invention uses orthogonal code encoding or frequency domain resource reuse to optimize resource utilization. Without significantly modifying the existing OFDM framework, frequency offset correction is achieved through intelligent sequence management, maintaining system performance. Through multi-sequence frequency offset coding, this invention not only solves the synchronization problem in ultra-high-speed environments but also expands the application scenarios of MESH networks while maintaining system efficiency.

[0047] These or other aspects of the invention will become more apparent from the following description of embodiments. It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. In the drawings:

[0049] Figure 1 This is a flowchart of a frequency offset synchronization method for an ultra-high-speed MESH wireless network according to the present invention.

[0050] Figure 2 This is a schematic diagram illustrating the transmission of multiple PSS sequences on different frequency domain resources in a frequency offset synchronization method for an ultra-high-speed MESH wireless network according to the present invention.

[0051] Figure 3 This is a schematic diagram of the frequency domain conversion of received data in a frequency offset synchronization method for an ultra-high-speed MESH wireless network according to the present invention. Detailed Implementation

[0052] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0053] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0054] like Figure 1 As shown, one embodiment of the present invention provides a frequency offset synchronization method for an ultra-high-speed MESH wireless network, comprising the following steps:

[0055] Step S10: The transmitting end generates N master synchronization signal PSS sequences, each PSS sequence having a different preset frequency offset value.

[0056] In this step, when the transmitter generates N master synchronization signal PSS sequences, the frequency offset values ​​of the N PSS sequences are symmetrically distributed, including positive frequency offset, zero frequency offset and negative frequency offset, and the frequency offset interval is Δf; where N is an integer greater than 1 and less than or equal to 9, and the frequency offset interval Δf is dynamically optimized according to the subcarrier interval and the operating frequency.

[0057] Step S20: The transmitting end transmits N PSS sequences to the receiving end through a wireless channel. The transmission method includes transmitting after orthogonal code encoding or transmitting on different frequency domain resources.

[0058] In this step, the transmitting end sends N PSS sequences at a time. The N PSS sequences are orthogonally encoded and then sent to the receiving end, or sent to different frequency domain resources.

[0059] For example, when the number of the N PSS sequences is 3, the frequency offset interval Δf is 4.5kHz, the allowable frequency offset is 13.5kHz, and the corresponding maximum speed is 2700m / s.

[0060] Step S30: After receiving the signal, the base receiver detects the N PSS sequences according to the transmission method, and infers the frequency offset prediction value based on the detected PSS sequence results.

[0061] In this step, after receiving the signal, the receiving end detects the N PSS sequences according to the transmission method. If the transmission method is orthogonal code encoding, the received orthogonally encoded PSS sequences are processed with orthogonal codes before PSS sequence detection. If the transmission method is transmission on different frequency domain resources, different PSS sequences are detected on different frequency domain resources respectively.

[0062] In this embodiment, see Figure 2 As shown, when the transmitter sends N PSS sequences on different frequency domain resources, the frequency domain resource allocation method is as follows: each PSS sequence occupies an independent frequency domain resource block, and the resource block interval is set based on the frequency offset value Δf to ensure minimal interference between sequences. Figure 2 The center frequency line set on the vertical Y-axis represents the frequency dimension. Different vertical positions correspond to different subcarriers. This invention uses the frequency domain (Y-axis) to distinguish different PSS sequences. The three PSSs (PSS1, PSS2, PSS3) are staggered on the frequency axis. Each PSS sequence has a preset frequency offset (+Δf, 0, -Δf) relative to the center frequency point in the frequency domain when it is generated. Figure 2 In the horizontal axis (X-axis), the OFDM Symbol represents the time dimension, with one unit being one OFDM symbol period. Symbols 0-3 on the horizontal axis indicate that the synchronization signal block lasts for four symbols in time. Symbol 0: used to transmit multiple PSSs to resolve frequency offset ambiguity. The receiver first completes the detection of multiple PSSs and frequency offset pre-estimation within this symbol. Symbols 1 and 2: mainly used to transmit PBCH (Physical Broadcast Channel) system information. After obtaining preliminary synchronization and frequency offset pre-correction in symbol 0, the receiver can more accurately demodulate the PBCH. Symbol 2, frequency-division multiplexed with the PBCH: used to transmit SSSs. After completing preliminary frequency offset pre-correction, the receiver uses the SSS for more accurate time synchronization and cell ID detection, and can combine PSS / SSS for fine frequency offset correction.

[0063] In this embodiment, when the transmitting end uses orthogonal code encoding to transmit N PSS sequences, the orthogonal code is Walsh code, and the encoded sequences are multiplexed and transmitted on the same frequency domain resources.

[0064] In this embodiment, when the receiving end infers the frequency offset prediction value based on the detected PSS sequence results, it selects the optimal value from multiple PSS detection results and inversely deduces the frequency offset based on the PSS sequence. See also... Figure 3 As shown, the received data frequency domain and the converted data include:

[0065] When there is no frequency offset, the receiver uses PSS1 / PSS2 / PSS3 to perform correlation calculations with the PSS data at the center frequency. PSS2 has the highest correlation peak. The frequency offset is then calculated using the received PSS and SSS data. See [link to relevant documentation]. Figure 3 As shown in (a), in the no-frequency-offset scenario, the received signal is perfectly synchronized with the transmitter, with no Doppler frequency offset. When calculating the frequency offset, the receiver converts the received signal to the frequency domain and performs correlation calculations with the local PSS1, PSS2, and PSS3 sequences at the center frequency. The correlation calculation uses a standard cross-correlation algorithm to calculate the similarity between each sequence and the received signal. The calculation results show that because PSS2 has a preset zero frequency offset, it perfectly matches the no-frequency-offset signal, resulting in the highest correlation peak value for the PSS2 sequence, while the peak values ​​for PSS1 and PSS3 are lower. When selecting the optimal value, since PSS2 has the highest peak value, the receiver determines that there is no significant frequency offset, and the frequency offset pre-estimate is directly taken as the preset frequency offset of PSS2, i.e., 0. When combining with SSS fine correction, the received PSS and SSS data are used, and fine correction calculated through phase difference further verifies that the frequency offset is close to zero, ensuring the accuracy of the estimation.

[0066] When the frequency offset is less than a preset threshold, the receiver uses PSS1 / PSS2 / PSS3 to perform correlation calculations with the PSS data at the center frequency point. The correlation peak of PSS2 is relatively high. The frequency offset is then calculated using the received PSS and SSS data. (See [link to relevant documentation]). Figure 3As shown in (b), in scenarios where the frequency offset is less than the preset threshold, there is a small frequency offset, but it does not exceed the capture range of PSS2. For example, the frequency offset interval Δf < the preset threshold, which is set to 15% of the subcarrier interval, i.e., 4.5kHz. When calculating the correlation of PSS data, the receiver also performs correlation calculations of PSS1 / PSS2 / PSS3. Due to the small frequency offset, the received signal has a slight offset in the frequency domain, but it is still near the zero frequency offset of PSS2. During peak detection, the correlation peak of PSS2 is relatively high, indicating that the direction of the frequency offset is unclear, but the magnitude is controllable. When selecting the optimal value for frequency offset inference, the peak value of PSS2 is used as the main reference, and the initial frequency offset estimate is set to 0. When combined with SSS fine correction, the phase difference between PSS and SSS is calculated through the joint processing of PSS and SSS, and the frequency offset value Δf2 is accurately calculated. The final frequency offset is the estimated value (0) plus the fine correction value Δf2, i.e., Δf_total=0+Δf2. This can avoid over-correction when the frequency offset is small, and improve efficiency through fine correction.

[0067] When the frequency offset exceeds a preset threshold, the receiver uses PSS1 / PSS2 / PSS3 and the PSS data at the center frequency point for correlation calculation. The correlation peak of PSS3 is relatively high. The receiver then uses the received PSS and SSS data to calculate the frequency offset Δf2. The final frequency offset is the sum of the frequency offsets Δf of PSS3 and PSS2, plus the frequency offset Δf2 calculated from PSS / SSS. (See [link to relevant documentation]). Figure 3 As shown in (c), in scenarios where the frequency offset is greater than a preset threshold, a large frequency offset, such as a frequency offset interval Δf > the preset threshold (exceeding 4.5 kHz), will cause ambiguity problems in traditional methods. During correlation calculation, the receiver performs PSS sequence correlation calculation. Due to the large frequency offset, the received signal is significantly shifted in the frequency domain, closer to the negative frequency offset region of PSS3; during peak detection, the correlation peak of PSS3 is relatively high, while the peak of PSS2 is lower, clearly indicating a negative frequency offset direction. During frequency offset inference, PSS3 is selected as the optimal sequence, and the pre-estimated frequency offset is taken as the preset frequency offset (-Δf) of PSS3. When combining with SSS fine correction, the fine correction frequency offset Δf2 is calculated using PSS and SSS data. The frequency offset between PSS and SSS can be calculated using publicly available algorithms such as the Cedron algorithm. The final frequency offset is the pre-estimated value (-Δf) plus the fine correction value Δf2, i.e., Δf_total = -Δf + Δf2. Since the frequency offset interval between PSS3 and PSS2 is Δf, the frequency offset pre-estimate already contains directional information. The fine correction value Δf2 is used to compensate for residual errors. Directional ambiguity is solved directly through sequence selection, supporting extreme high-speed scenarios.

[0068] Step S40: The receiving end applies the frequency offset pre-estimated value to perform frequency offset pre-correction processing on the received signal, and then performs fine frequency offset correction through the auxiliary synchronization signal SSS to complete synchronization.

[0069] In this step, the frequency offset pre-correction process includes frequency domain rotation or phase compensation of the received signal, and the pre-corrected signal is then subjected to SSS detection to achieve fine frequency offset correction.

[0070] The frequency offset synchronization method for ultra-high-speed MESH wireless networks in this embodiment is applicable to OFDM systems with a subcarrier spacing of 30kHz and an operating frequency of 1.5GHz. If the reliably detected frequency offset is less than 15%, then the allowable frequency offset is 30kHz * 15% = 4.5kHz, and the corresponding maximum speed is: C * Δf / F = 3 * 10 8 ×4500 / (1.5×10 9 =900m / s; when using 3 PSS sequences locally, the sequence frequency offset interval is 4.5KHz, then the allowed frequency offset is 13.5Khz, and the corresponding maximum supported moving speed is 2700m / s, which is close to Mach 8; among them, the frequency offset prediction allowable range is extended to 13.5kHz, which corresponds to the Doppler frequency offset tolerance being increased to 3 times that of the traditional method.

[0071] The frequency offset synchronization method and system for ultra-high-speed MESH wireless networks of this invention are also applicable to extreme scenarios, particularly suitable for unconventional mobile communication scenarios with Doppler frequency ranges such as satellite communication and ultra-high-speed mobile communication, breaking through speed limitations. For example, by using three PSS sequences, the maximum allowable frequency offset can be extended to 13.5kHz, corresponding to a speed of 2700m / s, close to Mach 8, improving speed tolerance by 3 times. This enables MESH networks to support high-speed mobile applications such as military communications like hypersonic UAV formations, low-Earth orbit satellite networks, and emergency communications, expanding the boundaries of wireless communication.

[0072] The frequency offset synchronization method for ultra-high-speed MESH wireless networks of this invention solves the ambiguity problem. In traditional synchronization methods, when the Doppler frequency offset exceeds half a subcarrier interval, integer multiple frequency offset ambiguity occurs, leading to synchronization failure. This invention, however, directly indicates the frequency offset direction through multiple PSS sequences with different frequency offsets, fundamentally eliminating ambiguity. Specifically, the transmitting end generates N PSS sequences, preset with positive, zero, and negative frequency offsets respectively. The receiving end, by detecting the correlation peaks of these sequences, can clearly determine the frequency offset direction, avoiding misjudgment and effectively solving the ambiguity problem.

[0073] Another embodiment of the present invention provides a frequency offset synchronization system for an ultra-high-speed MESH wireless network, comprising:

[0074] The transmitting device is configured to generate N PSS sequences with different preset frequency offset values ​​and transmit the N PSS sequences through a wireless channel;

[0075] The receiving device is configured to receive the PSS sequence, detect N PSS sequences, infer a frequency offset prediction value based on the detected PSS sequence results, and perform frequency offset correction processing on the received signal.

[0076] The transmitting and receiving devices constitute a MESH network node, supporting synchronization in ultra-high-speed mobile environments.

[0077] In this embodiment, the transmitting device includes:

[0078] The sequence generation module is used to generate N PSS sequences, each sequence having a different preset frequency offset value, the frequency offset values ​​being symmetrically distributed and spaced by Δf.

[0079] The transmission processing module is configured to encode the PSS sequence using orthogonal codes or transmit it on different frequency domain resources;

[0080] The radio frequency (RF) transmission module is used to transmit the processed signal to the wireless channel via an antenna.

[0081] The sending processing module includes an orthogonal coding unit and a resource mapping unit;

[0082] The orthogonal coding unit uses Wash code to encode N PSS sequences;

[0083] The resource mapping unit maps the encoded sequence onto frequency domain resources, and the frequency offset interval Δf is dynamically optimized based on the subcarrier interval and the operating frequency.

[0084] In this embodiment, the receiving device includes:

[0085] The signal receiving module is configured to receive wireless signals via an antenna and perform down-conversion processing.

[0086] The frequency domain conversion module is used to convert time-domain signals into frequency-domain signals;

[0087] The PSS detection module is configured to detect the correlation peaks of N PSS sequences in the frequency domain.

[0088] The frequency offset estimation module infers the frequency offset prediction value based on the PSS sequence with the highest correlation peak.

[0089] The correction processing module is used to perform frequency offset pre-correction and fine correction on the received signal.

[0090] The frequency offset synchronization system of the ultra-high-speed MESH wireless network supports OFDM modulation, with a subcarrier spacing of 15-120kHz and an operating frequency band of 0.5-6GHz; the system supports a maximum Doppler frequency offset of 13.5kHz, corresponding to a moving speed of 2700m / s.

[0091] In this invention, the positions and relative velocities of MESH network nodes change dynamically. By combining frequency offset pre-estimation and fine correction, the system's adaptability to dynamic topologies is improved. The receiver first performs frequency offset pre-correction, then performs fine correction via SSS, forming a two-stage correction mechanism that reduces synchronization time and improves accuracy. The PSS sequence in this invention uses orthogonal code encoding or frequency domain resource reuse to optimize resource utilization. Frequency offset correction is achieved through intelligent sequence management without significantly modifying the existing OFDM framework, maintaining system performance. Through multi-sequence frequency offset coding, this invention not only solves the synchronization problem in ultra-high-speed environments but also expands the application scenarios of MESH networks while maintaining system efficiency.

[0092] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A frequency offset synchronization method for an ultra-high-speed mesh wireless network, characterized in that, Includes the following steps: The transmitting end generates N master synchronization signal PSS sequences, each PSS sequence having a different preset frequency offset value; The transmitter sends N PSS sequences to the receiver via a wireless channel. The transmission methods include transmitting after orthogonal code encoding or transmitting on different frequency domain resources. After receiving the signal, the receiving end detects the N PSS sequences according to the transmission method, and infers the frequency offset prediction value based on the detected PSS sequence results. The receiving end applies the frequency offset pre-estimated value to perform frequency offset pre-correction processing on the received signal, and then performs fine frequency offset correction through the auxiliary synchronization signal SSS to complete synchronization.

2. The frequency offset synchronization method for ultra-high-speed MESH wireless networks as described in claim 1, characterized in that, When the transmitter generates N master synchronization signal (PSS) sequences, the frequency offset values ​​of the N PSS sequences are symmetrically distributed, including positive frequency offset, zero frequency offset, and negative frequency offset, with a frequency offset interval of Δf. Here, N is an integer greater than 1 and less than or equal to 9, and the frequency offset interval Δf is dynamically optimized according to the subcarrier spacing and operating frequency.

3. The frequency offset synchronization method for ultra-high-speed MESH wireless networks as described in claim 2, characterized in that, The transmitting end sends N PSS sequences at a time. The N PSS sequences are encoded with orthogonal codes and then sent to the receiving end, or they are sent to different frequency domain resources.

4. The frequency offset synchronization method for ultra-high-speed MESH wireless networks as described in claim 3, characterized in that, When the number of the N PSS sequences is 3, the frequency offset interval Δf is 4.5kHz, the allowable frequency offset is 13.5kHz, and the corresponding maximum speed is 2700m / s.

5. The frequency offset synchronization method for ultra-high-speed MESH wireless network as described in claim 1, when the receiving end detects the N PSS sequences according to the transmission method after receiving the signal, if the transmission method is orthogonal code encoding, then the received orthogonally encoded PSS sequences are processed by orthogonal code before PSS sequence detection; if the transmission method is transmission on different frequency domain resources, then different PSS sequences are detected on multiple frequency domain resources respectively.

6. The frequency offset synchronization method for ultra-high-speed MESH wireless networks as described in claim 1, characterized in that, When the receiver infers the frequency offset prediction value based on the detected PSS sequence results, it selects the optimal value from multiple PSS detection results and inversely derives the frequency offset based on the PSS sequence. The received data frequency domain and the converted data include: When there is no frequency offset, the receiver uses PSS1 / PSS2 / PSS3 to perform correlation calculations with the PSS data at the center frequency point. PSS2 has the highest correlation peak, and the frequency offset is calculated using the received PSS and SSS data. When the frequency offset is less than the preset threshold, the receiver uses PSS1 / PSS2 / PSS3 to perform correlation calculation with the PSS data at the center frequency point. The correlation peak of PSS2 is relatively high, and the frequency offset is calculated using the received PSS and SSS data. When the frequency offset is greater than the preset threshold, the receiver uses PSS1 / PSS2 / PSS3 to perform correlation calculation with the PSS data at the center frequency point. The correlation peak of PSS3 is relatively high, and the frequency offset Δf2 is calculated using the received PSS and SSS data. The final frequency offset is the frequency offset Δf of PSS3 and PSS2 plus the frequency offset Δf2 calculated by PSS / SSS.

7. The frequency offset synchronization method for ultra-high-speed MESH wireless networks as described in claim 6, characterized in that, Frequency offset pre-correction processing includes frequency domain rotation or phase compensation of the received signal, and the pre-corrected signal is then subjected to SSS detection to achieve fine frequency offset correction.

8. The frequency offset synchronization method for ultra-high-speed MESH wireless networks as described in claim 1, characterized in that, The frequency offset synchronization method of the ultra-high-speed MESH wireless network is applicable to OFDM systems with a subcarrier spacing of 30kHz and an operating frequency of 1.5GHz, and supports a maximum mobile speed of 2700m / s; wherein, the allowable range of frequency offset pre-estimation is extended to 13.5kHz.

9. A frequency offset synchronization system for an ultra-high-speed mesh wireless network, characterized in that, The steps for performing the frequency offset synchronization method for an ultra-high-speed MESH wireless network as described in any one of claims 1-8, wherein the frequency offset synchronization system of the ultra-high-speed MESH wireless network comprises: The transmitting device is configured to generate N PSS sequences with different preset frequency offset values ​​and transmit the N PSS sequences through a wireless channel; The receiving device is configured to receive the PSS sequence, detect N PSS sequences, infer a frequency offset prediction value based on the detected PSS sequence results, and perform frequency offset correction processing on the received signal. The transmitting and receiving devices constitute a MESH network node, supporting synchronization in ultra-high-speed mobile environments.

10. The frequency offset synchronization system for the ultra-high-speed MESH wireless network as described in claim 9, characterized in that, The transmitting device includes: The sequence generation module is used to generate N PSS sequences, each sequence having a different preset frequency offset value, the frequency offset values ​​being symmetrically distributed and spaced by Δf. The transmission processing module is configured to encode the PSS sequence using orthogonal codes or transmit it on different frequency domain resources; The radio frequency (RF) transmission module is used to transmit the processed signal to the wireless channel via an antenna.

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