A method for tracking transmission power and receiving power in a Wi-Fi system

Abstract

The present invention discloses a method for tracking the transmission power and receiving power in a Wi-Fi system, which utilizes the characteristics of the pilot subcarrier of the Wi-Fi OFDM symbol to perform power tracking in frequency, specifically comprising the following steps: S1, according to a fixed symbol interval N avg Calculate the average power of all frequency domain pilot subcarriers; S2, record the first output result as the reference power of power tracking; S3, at a fixed symbol interval N avg , the instantaneous value of power tracking is smoothed; S4, according to the fixed symbol interval N avg The power tracking value is calculated according to the formula. The present invention uses pilot-based power estimation to effectively track PA output power, effectively resolving the prior art issue of OFDM signals being unable to use the average power of the time domain signal for power tracking due to the non-constant amplitude characteristics and high peak-to-average ratio of the time domain signal.

Description

Technical Field

[0001] The present invention relates to the field of communication signal technology, and in particular to a method for tracking transmission power and receiving power in a Wi-Fi system. Background Art

[0002] Due to the non-ideal temperature characteristics of RF components such as PAs, the power of Wi-Fi signals varies over time within a frame. Furthermore, the long pilot symbols (used for channel estimation) of OFDM signals exist only in the frame header (except when HE midamble is enabled). Furthermore, the transmission / reception of high-order modulation schemes such as MCS11 places very strict power control requirements (<0.1dB), namely:

[0003] When receiving, it is necessary to track and compensate the power of the received signal;

[0004] When transmitting, it is necessary to track and compensate the power of the transmitted signal.

[0005] However, due to the non-constant amplitude characteristics and peak-to-average power ratio of OFDM signals in the time domain, it is impossible to use the average power of the time domain signal for power tracking.

[0006] Therefore, a method for tracking the sending power and receiving power in a Wi-Fi system is proposed. Summary of the Invention

[0007] The present invention aims to provide a method for tracking transmission power and receiving power in a Wi-Fi system.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention proposes a method for tracking transmit power and receive power in a Wi-Fi system, which utilizes the characteristics of the pilot subcarrier of the Wi-Fi OFDM symbol to perform power tracking at frequency, and specifically includes the following steps:

[0010] S1, according to the fixed symbol interval N avg Calculate the average power of all frequency-domain pilot subcarriers;

[0011] S2. Record the first output result as the reference power for power tracking;

[0012] S3, according to the fixed symbol interval N avg , further smoothing the average power of all currently obtained frequency domain pilot subcarriers;

[0013] S4, according to the fixed symbol interval N avg , perform power tracking based on the smoothed average power:

[0014]

[0015] R max is the threshold value that triggers power adjustment, L step is the step value of power adjustment;

[0016] At a fixed symbol interval N avg , adjust the digital power gain;

[0017] DAGC Cur =DAGC Cur ·(1+L track ).

[0018] In some possible implementations, in step S4,

[0019] When receiving power tracking, press DAGC cur A digital power gain compensation module for adjusting the receiving path;

[0020] When transmitting power tracking, press DAGC cur Adjust the digital power gain compensation module of the transmission path.

[0021] In some possible implementations, during the transmit power tracking, the transmit output signal needs to be looped back to the receive path of the receiver to serve as the receiver input, and the receive path is enabled for corresponding demodulation.

[0022] In some possible implementations, the characteristics of the pilot subcarriers of the Wi-Fi OFDM symbols include the following:

[0023] The pilot subcarrier is fixed at the frequency subcarrier position, that is, the fading is consistent and is not affected by the frequency fading of the wireless channel;

[0024] The pilot subcarrier modulation mode is fixed to BPSK, that is, the signal power of different time domain symbols is fixed.

[0025] In some possible implementations, in step S1, the calculation formula for the average power of all frequency-domain pilot subcarriers is as follows:

[0026] Where n refers to the result of n calculations, Refers to the pilot subcarrier set in the OFDM data symbols received from the n-1th calculation to the nth calculation, X k Refers to the signal of the kth pilot subcarrier received.

[0027] In some possible implementations, in step S2, the first output result is recorded as the calculation formula of the reference power for power tracking as follows:

[0028] PRef =P Pilot (0).

[0029] In some possible implementations, in step S3, the average power of all currently obtained frequency domain pilot subcarriers is further smoothed as follows:

[0030]

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention can effectively track the PA output power by performing power estimation based on the Pilot, and effectively solves the problem in the prior art that the average power of the OFDM signal cannot be used for power tracking due to the non-constant amplitude characteristics and high peak-to-average ratio of the time domain signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flowchart of the received power tracking in the present invention;

[0034] Figure 2 This is a flow chart of transmit power tracking in the present invention;

[0035] Figure 3 It is a line graph of experimental data in the experiment of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The present invention proposes a method for tracking transmit and receive power in a Wi-Fi system, which uses the following characteristics of the pilot subcarrier of the Wi-Fi OFDM symbol to perform power tracking at frequency:

[0038] 1) The pilot subcarrier is fixed at the frequency subcarrier position, i.e., the fading is consistent and is not affected by the frequency fading of the wireless channel;

[0039] 2) The pilot subcarrier modulation mode is fixed to BPSK, that is, the signal power of different time domain symbols is fixed.

[0040] The details are as follows:

[0041] 1. According to the fixed symbol interval N avg Calculate the average power of all frequency-domain pilot subcarriers

[0042] (The purpose is to increase calculation accuracy)

[0043]

[0044] 2. Record the first output result as the reference power for power tracking, that is

[0045] P Ref =P Pilot (0)

[0046] 3. According to the fixed symbol interval N avg , the average power of all the currently obtained frequency domain pilot subcarriers is further smoothed, for example, a smoothing filter can be used to express it as

[0047]

[0048] 4. According to the fixed symbol interval N avg , power tracking is performed based on the smoothed average power

[0049]

[0050] R max is the threshold value that triggers power adjustment, L step is the step value of power adjustment

[0051] At a fixed symbol interval N avg , adjust the digital power gain

[0052] DAGC Cur =DAGC Cur ·(1+L track )

[0053] For the above, if it is receiving power tracking, press DAGC cur Adjust the digital power gain compensation module of the receiving path, such as Figure 1 shown.

[0054] For the above, if it is transmit power tracking, press DAGC cur Adjust the digital power gain compensation module of the transmit path. In addition, if transmit power tracking is used, the transmit output signal needs to be looped back to the receiver's receive path as the receiver's input, and the receive path needs to be opened for corresponding demodulation (the transmit output signal needs to be looped back to the Rx path input, and the Rx path needs to be opened for corresponding demodulation). Figure 2 shown.

[0055] The above method was used to conduct experiments, such as Figure 3 As shown, experimental data were obtained.

[0056] 1) As can be seen from the blue line, power estimation based on the pilot can effectively track changes in PA output power;

[0057] 2) The purple line shows that the compensation result is close to ideal;

[0058] 3) In addition, the experimental results show that without power compensation, the EVM is 31dB. After power compensation, the EVM increases to 40dB.

[0059] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0060] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for tracking transmit power and receive power in a Wi-Fi system, characterized by: Using the characteristics of the pilot pil ot subcarrier of the WiFi OFDM symbol to perform power tracking at frequency, the specific steps include: S1, according to the fixed symbol interval N avg Calculate the average power of all frequency-domain pilot subcarriers; S2. Record the first output result as the reference power for power tracking; S3, according to the fixed symbol interval N avg , further smoothing the average power of all currently obtained frequency domain pilot subcarriers; S4, according to the fixed symbol interval N avg , perform power tracking based on the smoothed average power: R max is the threshold value that triggers power adjustment, L step is the step value of power adjustment; At a fixed symbol interval N avg , adjust the digital power gain; DAGC Cur =DAGC Cur ·(1+L track )。 2. The method for tracking transmit power and receive power in a Wi-Fi system according to claim 1, wherein: In the step S4, When receiving power tracking, press DAGC cur A digital power gain compensation module for adjusting the receiving path; When transmitting power tracking, press DAGC cur Adjust the digital power gain compensation module of the transmission path.

3. The method for tracking transmit power and receive power in a Wi-Fi system according to claim 2, wherein: During the transmission power tracking, the transmission output signal needs to be looped back to the receiving path of the receiver to serve as the input of the receiver, and the receiving path is opened for corresponding demodulation.

4. The method for tracking transmit power and receive power in a Wi-Fi system according to claim 1, wherein: In step S1, the calculation formula for the average power of all frequency-domain pilot subcarriers is as follows: Where n refers to the result of n calculations, Refers to the pilot subcarrier set in the OFDM data symbols received from the n-1th calculation to the nth calculation, X k Refers to the signal of the kth pilot subcarrier received.

5. The method for tracking transmit power and receive power in a Wi-Fi system according to claim 1, wherein: In step S2, the first output result is recorded as the calculation formula of the reference power for power tracking as follows: P Ref =P Pilot (0)。 6. The method for tracking transmit power and receive power in a Wi-Fi system according to claim 1, wherein: In step S3, the average power of all the currently obtained frequency domain pilot subcarriers is further smoothed in the following manner:

Images