Method for detecting access signal in wireless ad hoc network

Abstract

The invention discloses a method for detecting access signals in a wireless ad hoc network, and relates to the technical field of wireless broadband ad hoc networks. Based on a TDMA (Time Division Multiple Access) scheme, a plurality of subframes are divided in a frame structure, one or more subframes in the subframes are used as synchronous subframes, the synchronous subframes are composed of a plurality of OFDM (Orthogonal Frequency Division Multiplexing) symbols, and the last one or two symbols of the synchronous subframes are dynamically appointed as idle time slots according to resource use conditions and are used as detection access signals, so that users access signals or synchronous signals. According to pre-allocated parameters, determining the condition of sending a signal by detecting the access signal: whether the sending signal occupies all spectrum resources and whether subcarriers of the sending signal are continuous; and according to the condition of the transmitted signal, calculating time synchronization in the frequency domain or the time domain, estimating the frequency deviation in the frequency domain or the time domain, and estimating the power of the signal in the frequency domain or the time domain for controlling the power of the transmitted signal.

Description

Technical Field

[0001] The present invention discloses a method for detecting access signals in a wireless ad-hoc network, which relates to the technical field of wireless broadband ad-hoc networks. Background Art

[0002] A wireless ad-hoc network is a wireless communication network in which nodes can autonomously form a temporary network without infrastructure or central control. Wireless ad-hoc networks have unique advantages in terms of flexibility and scalability and are widely used in military communications, emergency rescue, Internet of Things and other fields.

[0003] In a wireless ad-hoc network, time-frequency synchronization between nodes is crucial for achieving efficient communication and collaboration. The transmission and reception of detection signals are crucial for the time calibration of nodes to ensure that nodes communicate within the same time interval.

[0004] Currently, there is a lack of signal design for comprehensive functions such as time and frequency synchronization in ad-hoc network systems. The design of synchronization signals is only based on a single requirement, such as dealing with time synchronization or frequency synchronization separately, and generally synchronizes based on the Global Positioning System (GPS). However, the synchronization method relying on GPS signals may be limited in certain scenarios, such as in indoor environments, urban canyons or densely built-up areas with severe occlusion, and there is a lack of effective mechanisms to handle user access or synchronization. In an ad-hoc network system, due to the lack of a unified synchronization signal, there will be relatively large uncertainties in the access signals of each user, including large time and frequency errors, and the signal power also deviates greatly from the expected value. In addition, relying on GPS signals also increases the cost and energy consumption of the system, limiting the application scope of wireless ad-hoc networks in various application fields. Summary of the Invention

[0005] Aiming at the problems of the prior art, the present invention provides a method for detecting access signals in a wireless ad-hoc network, providing access signal detection with higher accuracy, more reliability and applicable to various environments to meet the initial access or re-synchronization requirements of wireless ad-hoc networks in various environments.

[0006] The specific solution proposed by the present invention is:

[0007] The present invention provides a method for detecting access signals in a wireless ad-hoc network. Based on the TDMA multiple access scheme, several sub-frames are divided in the frame structure, and one or more sub-frames in the sub-frames are used as synchronization sub-frames. The synchronization sub-frames are composed of several OFDM symbols. According to the resource usage situation, the last one or two symbols of the synchronization sub-frame are dynamically designated as idle time slots for detecting access signals, and used for user access signals or synchronization signals.

[0008] Determine the situation of the transmitted signal by detecting the access signal according to the pre-allocated parameters:

[0009] Whether the transmitted signal occupies all the spectrum resources and whether the subcarriers of the transmitted signal are continuous;

[0010] According to the situation of the transmitted signal, calculate the time synchronization in the frequency domain or time domain, estimate the frequency deviation in the frequency domain or time domain, and estimate the power of the signal in the frequency domain or time domain for the power control of the transmitted signal.

[0011] Furthermore, the determining the situation of the transmitted signal by detecting the access signal in the method for detecting the access signal of a wireless ad hoc network includes four results, which are respectively:

[0012] The transmitted signal occupies all the spectrum resources and the subcarriers are continuous;

[0013] The transmitted signal occupies all the spectrum resources and the subcarriers are not continuous;

[0014] The transmitted signal occupies part of the spectrum resources and the subcarriers are continuous;

[0015] The transmitted signal occupies part of the spectrum resources and the subcarriers are not continuous.

[0016] Furthermore, according to the situation of the transmitted signal in the method for detecting the access signal of a wireless ad hoc network, calculating the time synchronization in the frequency domain or time domain includes:

[0017] Calculate the time synchronization in the frequency domain: For an OFDM signal, the time deviation τ corresponds to the phase rotation ωτ of the subcarrier signal in the frequency domain, that is:

[0018]

[0019] Use ωτ to calculate the time deviation τ;

[0020] Calculate the time synchronization in the time domain: Perform a sliding correlation calculation on the time-domain signals of the received signal and the transmitted signal, and determine the path delay or time synchronization of the transmitted signal according to the position of the correlation peak.

[0021] Furthermore, according to the situation of the transmitted signal in the method for detecting the access signal of a wireless ad hoc network, estimating the frequency deviation in the frequency domain or time domain includes:

[0022] Estimate the frequency deviation in the frequency domain: According to the fact that the magnitude of signal leakage in the frequency-domain frequency deviation is proportional to the frequency deviation, estimate the frequency deviation of the received signal;

[0023] Estimate the time-domain frequency offset: When the subcarriers of the transmitted signal are discontinuous and the subcarrier spacing is fixed, the signal will have a periodically repeating characteristic in the time domain. Assuming the subcarrier spacing is 1, the signal period in the time domain is half of the OFDM symbol duration, and the frequency deviation is obtained by correlating and accumulating adjacent time-domain signals.

[0024] The present invention also provides a device for detecting access signals in a wireless ad hoc network, including a frame management module, a transmission situation management module, and a synchronization management module.

[0025] Based on the TDMA multiple access scheme, the frame management module divides several subframes in the frame structure, designates one or more subframes in the subframes as synchronization subframes. The synchronization subframes are composed of several OFDM symbols. According to the resource usage situation, the last one or two symbols of the synchronization subframe are dynamically designated as idle time slots for detecting access signals, for user access signals or synchronization signals.

[0026] The transmission situation management module determines the situation of the transmitted signal by detecting the access signal according to the pre-allocated parameters:

[0027] Whether the transmitted signal occupies all the spectrum resources and whether the subcarriers of the transmitted signal are continuous;

[0028] The synchronization management module calculates time synchronization in the frequency domain or time domain according to the situation of the transmitted signal, estimates the frequency deviation in the frequency domain or time domain, and estimates the power of the signal in the frequency domain or time domain for power control of the transmitted signal.

[0029] Further, the transmission situation management module of the device for detecting access signals in a wireless ad hoc network detects the access signal to determine the situation of the transmitted signal, including four results, which are respectively:

[0030] The transmitted signal occupies all the spectrum resources and the subcarriers are continuous;

[0031] The transmitted signal occupies all the spectrum resources and the subcarriers are discontinuous;

[0032] The transmitted signal occupies part of the spectrum resources and the subcarriers are continuous;

[0033] The transmitted signal occupies part of the spectrum resources and the subcarriers are discontinuous.

[0034] Further, the synchronization management module of the device for detecting access signals in a wireless ad hoc network calculates time synchronization in the frequency domain or time domain according to the situation of the transmitted signal, including:

[0035] Calculate the frequency-domain time synchronization: For an OFDM signal, the time deviation τ corresponds to the phase rotation ωτ of the subcarrier signal in the frequency domain, that is:

[0036]

[0037] Calculate the time deviation τ using ωτ;

[0038] Calculate time domain time synchronization: perform sliding correlation calculation on the time domain signals of the received signal and the transmitted signal, and determine the path delay or time synchronization of the transmitted signal according to the position of the correlation peak.

[0039] Furthermore, the synchronization management module of the device for detecting and accessing signals in a wireless ad hoc network estimates the frequency deviation in the frequency domain or time domain according to the situation of the transmitted signal, including:

[0040] Estimate the frequency domain frequency offset: estimate the frequency deviation of the received signal according to the fact that the magnitude of signal leakage in the frequency domain frequency offset is proportional to the frequency deviation;

[0041] Estimate the time domain frequency offset: when the subcarriers of the transmitted signal are discontinuous and the subcarrier interval is fixed, the signal will have a periodic repetition characteristic in the time domain. Assuming the subcarrier interval is 1, the signal period in the time domain is half of the OFDM symbol duration, and the frequency deviation is obtained by correlating and accumulating adjacent time domain signals.

[0042] The advantages of the present invention are:

[0043] The present invention provides a flexible detection signal transmission configuration, which not only meets the time synchronization requirements of a wireless ad hoc network in various environments, but also meets the requirements of transmit power control and receive channel gain control at the same time. The detection signal is transmitted in the idle time slot, which does not affect the normal data reception of the receiver and simplifies the system hardware design. Description of the Drawings

[0044] Figure 1 It is a schematic diagram of the ad hoc network frame structure.

[0045] Figure 2 It is a schematic diagram of a single user occupying all spectrum resources and having continuous subcarriers.

[0046] Figure 3 It is a schematic diagram of multiple users occupying all spectrum resources and having continuous subcarriers.

[0047] Figure 4 It is a schematic diagram of a single user occupying all spectrum resources and having discontinuous subcarriers.

[0048] Figure 5 It is a schematic diagram of multiple users occupying all spectrum resources and having discontinuous subcarriers. Detailed Embodiments

[0049] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments cited do not limit the present invention.

[0050] Embodiment 1

[0051] The present invention provides a method for detecting access signals in a wireless ad hoc network. Based on the TDMA multiple access scheme, several subframes are divided in the frame structure, and one or more subframes in the subframes are used as synchronization subframes. The synchronization subframes are composed of several OFDM symbols. According to the resource usage situation, the last one or two symbols of the synchronization subframe are dynamically designated as idle time slots for detecting access signals, for user access signals or synchronization signals. The detection synchronization signal is located at the end of the subframe, which will not affect the normal signal processing flow of the system, and can simplify the system design complexity; due to dynamic resource scheduling, the time-frequency resource usage efficiency of the system can be significantly improved.

[0052] According to the pre-allocated parameters, determine the situation of the transmitted signal by detecting the access signal:

[0053] Whether the transmitted signal occupies all the spectrum resources and whether the subcarriers of the transmitted signal are continuous.

[0054] Among them, determining the situation of the transmitted signal by detecting the access signal includes four results, which are:

[0055] The transmitted signal occupies all the spectrum resources and the subcarriers are continuous;

[0056] The transmitted signal occupies all the spectrum resources and the subcarriers are not continuous;

[0057] The transmitted signal occupies part of the spectrum resources and the subcarriers are continuous;

[0058] The transmitted signal occupies part of the spectrum resources and the subcarriers are not continuous.

[0059] According to the situation of the transmitted signal, calculate the time synchronization in the frequency domain or time domain, estimate the frequency deviation in the frequency domain or time domain, and estimate the power of the signal in the frequency domain or time domain for power control of the transmitted signal.

[0060] Among them, according to the situation of the transmitted signal, calculate the

[0061] time synchronization in the frequency domain or time domain, including:

[0062] Calculate the time synchronization in the frequency domain: For an OFDM signal, the OFDM signal is a continuous-time signal composed of multiple OFDM symbols, which is usually used to describe the entire transmission process.

[0063] The time deviation τ corresponds to the phase rotation ωτ of the subcarrier signal in the frequency domain, that is:

[0064]

[0065] Obtain the time deviation τ by calculating with ωτ;

[0066] Calculate time domain time synchronization: perform sliding correlation calculation on the time domain signals of the received signal and the transmitted signal, and determine the path delay or time synchronization of the transmitted signal according to the position of the correlation peak.

[0067] Estimate the frequency deviation in the frequency domain or time domain according to the situation of the transmitted signal, including:

[0068] Estimate the frequency domain frequency offset: estimate the frequency deviation of the received signal according to the fact that the signal leakage in the frequency domain frequency offset is proportional to the frequency deviation;

[0069] Estimate the time domain frequency offset: when the subcarriers of the transmitted signal are discontinuous and the subcarrier interval is fixed, the signal will have the characteristic of periodic repetition in the time domain. Assuming the subcarrier interval is 1, the signal period in the time domain is half of the OFDM symbol duration, and the frequency deviation is obtained by correlating and accumulating adjacent time domain signals, that is

[0070] obtained.

[0071] The power estimation of the signal can be carried out in the frequency domain or time domain, and the power estimation result of the signal will be used for the power control of the transmitted signal. The receiving device realizes the power control of the transmitting device and the gain setting of the receiving channel by detecting the signal power of the detection signal transmitted by the transmitting device in the specified time slot.

[0072] Embodiment 2

[0073] The present invention also provides a device for detecting and accessing signals in a wireless ad hoc network, including a frame management module, a transmission situation management module, and a synchronization management module

[0074] Based on the TDMA multiple access scheme, the frame management module divides several subframes in the frame structure, takes one or more subframes in the subframes as synchronization subframes. The synchronization subframes are composed of several OFDM symbols. According to the resource usage situation, the last one or two symbols of the synchronization subframe are dynamically specified as idle time slots for detecting access signals, for user access signals or synchronization signals.

[0075] The transmission situation management module determines the situation of the transmitted signal by detecting the access signal according to the pre-allocated parameters:

[0076] Whether the transmitted signal occupies all the spectrum resources and whether the subcarriers of the transmitted signal are continuous;

[0077] The synchronization management module calculates time synchronization in the frequency domain or time domain according to the situation of the transmitted signal, estimates the frequency deviation in the frequency domain or time domain, and estimates the power of the signal in the frequency domain or time domain for power control of the transmitted signal.

[0078] Regarding the information interaction and execution process among the modules in the above device, since they are based on the same concept as the method embodiments of the present invention, the specific content can be referred to the description in the method embodiments of the present invention and will not be elaborated here.

[0079] Similarly, the device of the present invention provides a flexible configuration for transmitting detection signals, which not only meets the time synchronization requirements of wireless ad hoc networks in various environments, but also meets the requirements of transmit power control and receive channel gain control. The detection signal is transmitted in the idle time slot, which does not affect the normal data reception of the receiver and simplifies the system hardware design.

[0080] It should be noted that not all steps and modules in the above processes and device structures are necessary, and some steps or modules can be ignored according to actual needs. The execution order of each step is not fixed and can be adjusted according to needs. The system structure described in the above embodiments can be a physical structure or a logical structure, that is, some modules may be implemented by the same physical entity, or some modules may be implemented by multiple physical entities, or some components in multiple independent devices can be jointly implemented.

[0081] The above embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. A method for detecting access signals in a wireless ad hoc network, characterized in that Based on the TDMA multiple access scheme, several sub-frames are divided in the frame structure, and one or more sub-frames in the sub-frames are used as synchronization sub-frames. The synchronization sub-frames are composed of several OFDM symbols. According to the resource usage situation, the last one or two symbols of the synchronization sub-frame are dynamically designated as idle time slots for use as probing access signals for user access signals or synchronization signals. According to the pre-allocated parameters, determine the situation of the transmitted signal through the probing access signal: Whether the transmitted signal occupies all the spectrum resources and whether the sub-carriers of the transmitted signal are continuous; According to the situation of the transmitted signal, calculate the time synchronization in the frequency domain or time domain, estimate the frequency deviation in the frequency domain or time domain, and estimate the power of the signal in the frequency domain or time domain for the power control of the transmitted signal.

2. The method for detecting and accessing signals in a wireless ad hoc network according to claim 1, wherein The determination of the transmitted signal situation through the probing access signal includes four results, which are respectively: The transmitted signal occupies all the spectrum resources and the sub-carriers are continuous; The transmitted signal occupies all the spectrum resources and the sub-carriers are not continuous; The transmitted signal occupies part of the spectrum resources and the sub-carriers are continuous; The transmitted signal occupies part of the spectrum resources and the sub-carriers are not continuous.

3. A method for detecting an access signal in a wireless ad hoc network according to claim 1, characterized in that According to the situation of the transmitted signal, calculate the time synchronization in the frequency domain or time domain, including: Calculate the frequency domain time synchronization: For OFDM signals, the time deviation τ corresponds to the phase rotation ωτ of the sub-carrier signal in the frequency domain, that is: Use ωτ to calculate and obtain the time deviation τ; Calculate the time domain time synchronization: Perform a sliding correlation calculation on the time domain signals of the received signal and the transmitted signal, and determine the path delay or time synchronization of the transmitted signal according to the position of the correlation peak.

4. A method for detecting an access signal in a wireless ad hoc network according to claim 1, characterized in that According to the situation of the transmitted signal, estimate the frequency deviation in the frequency domain or time domain, including: Estimate the frequency domain frequency offset: According to the fact that the magnitude of signal leakage in the frequency domain frequency offset is proportional to the frequency deviation, estimate the frequency deviation of the received signal; Estimate the time domain frequency offset: When the sub-carriers of the transmitted signal are not continuous and the sub-carrier interval is fixed, the signal will have a periodic repetition characteristic in the time domain. Assuming the sub-carrier interval is 1, the signal period in the time domain is half of the OFDM symbol duration, and the frequency deviation is obtained by correlating and accumulating adjacent time domain signals.

5. A device for detecting access signals in a wireless ad hoc network, characterized in that Including a frame management module, a transmission situation management module, and a synchronization management module The frame management module, based on the TDMA multiple access scheme, divides several sub-frames in the frame structure, and uses one or more sub-frames in the sub-frames as synchronization sub-frames. The synchronization sub-frames are composed of several OFDM symbols. According to the resource usage situation, the last one or two symbols of the synchronization sub-frame are dynamically designated as idle time slots for use as probing access signals for user access signals or synchronization signals. The transmission situation management module determines the situation of the transmitted signal through the probing access signal according to the pre-allocated parameters: Whether the transmitted signal occupies all the spectrum resources and whether the sub-carriers of the transmitted signal are continuous; The synchronization management module calculates the time synchronization in the frequency domain or time domain according to the situation of the transmitted signal, estimates the frequency deviation in the frequency domain or time domain, and estimates the power of the signal in the frequency domain or time domain for the power control of the transmitted signal.

6. The device for detecting and accessing signals in a wireless ad hoc network according to claim 5, characterized in that The determination of the transmitted signal situation by the transmission situation management module through the probing access signal includes four results, which are respectively: The transmitted signal occupies all the spectrum resources and the sub - carriers are continuous; The transmitted signal occupies all the spectrum resources and the sub - carriers are discontinuous; The transmitted signal occupies part of the spectrum resources and the sub - carriers are continuous; The transmitted signal occupies part of the spectrum resources and the sub - carriers are discontinuous.

7. The device for detecting and accessing signals in a wireless ad hoc network according to claim 5, characterized in that The synchronization management module calculates time synchronization in the frequency domain or time domain according to the situation of the transmitted signal, including: Calculating frequency - domain time synchronization: For OFDM signals, the time deviation τ corresponds to the phase rotation ωτ of the sub - carrier signal in the frequency domain, that is: Calculating the time deviation τ using ωτ; Calculating time - domain time synchronization: Performing sliding correlation calculation on the time - domain signals of the received signal and the transmitted signal, and determining the path delay or time synchronization of the transmitted signal according to the position of the correlation peak.

8. The device for detecting and accessing signals in a wireless ad hoc network according to claim 5, characterized in that The synchronization management module estimates the frequency deviation in the frequency domain or time domain according to the situation of the transmitted signal, including: Estimating frequency - domain frequency offset: Estimating the frequency deviation of the received signal according to the fact that the magnitude of signal leakage in the frequency - domain frequency offset is proportional to the frequency deviation; Estimating time - domain frequency offset: When the sub - carriers of the transmitted signal are discontinuous and the sub - carrier spacing is fixed, the signal will have a periodically repeated characteristic in the time domain. Assuming the sub - carrier spacing is 1, the signal period in the time domain is half of the OFDM symbol duration, and the frequency deviation is obtained by correlating and accumulating adjacent time - domain signals.

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