Communication device and effective signal detection method

Abstract

The effective signal detection method comprises the following operations: receiving a communication signal via receiver circuitry, wherein the communication signal comprises a plurality of symbols; calculating a delay correlation function according to the plurality of symbols to determine whether the communication signal is valid; and when it is determined that the communication signal is valid according to at least one first symbol of the plurality of symbols, performing a first gain control according to at least one second symbol of the plurality of symbols to adjust a first gain of the receiver circuitry, wherein the at least one second symbol follows the at least one first symbol; and when it is judged that the communication signal is not valid according to the delay correlation function, stopping the first gain control and stopping processing the communication signal.

Description

Technical Field

[0001] The present invention relates to a communication device, and in particular to a communication device and an effective signal detection method thereof which can utilize delay correlation to improve the effective signal detection speed. Background Art

[0002] In practical applications, the communication signal received by the communication system is usually a valid signal, interference, or a combination of the two. In the prior art, if the communication system is affected by interference and initially misjudges the interference as a valid signal, the communication system needs to wait until the frame start delimiter to determine that the signal is interference, resulting in the inability to immediately receive other valid signals. In other technologies, the communication system can also use energy monitoring to distinguish interference from valid signals. However, if the energy of the interference is close to the energy of the valid signal, the communication system cannot correctly distinguish the interference from the valid signal. Summary of the invention

[0003] In some embodiments, one of the objectives of the present invention is (but not limited to) to provide a communication device and an effective signal detection method thereof that can utilize delay correlation to increase the effective signal detection speed, so as to improve the deficiencies of the prior art.

[0004] In some embodiments, the communication device includes a receiver circuit system, a processor circuit, and a gain control circuit system. The receiver circuit system is used to receive a communication signal, wherein the communication signal includes a plurality of symbols. The processor circuit is used to calculate a delay correlation function based on the plurality of symbols to determine whether the communication signal is valid. The gain control circuit system is used to start when the processor circuit determines that the communication signal is valid based on at least one first symbol in the plurality of symbols, so as to perform a first gain control based on at least one second symbol in the plurality of symbols to adjust the first gain of the receiver circuit system. Wherein the at least one second symbol follows the at least one first symbol, and when the processor circuit determines that the communication signal is not valid based on the delay correlation function, the processor circuit stops the first gain control and stops processing the communication signal.

[0005] In some embodiments, a valid signal detection method includes the following operations: receiving a communication signal via a receiver circuit system, wherein the communication signal includes multiple symbols; calculating a delay correlation function based on the multiple symbols to determine whether the communication signal is valid; and when the communication signal is determined to be valid based on at least one first symbol among the multiple symbols, performing a first gain control based on at least one second symbol among the multiple symbols to adjust a first gain of the receiver circuit system, wherein the at least one second symbol follows the at least one first symbol; and when the communication signal is determined not to be valid based on the delay correlation function, stopping the first gain control and stopping processing the communication signal.

[0006] The features, practical operation and efficacy of the present invention are described in detail below through a number of embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic diagram of a communication device drawn according to some embodiments of the present invention;

[0008] Figure 2 is a flow chart of an effective signal detection method drawn according to some embodiments of the present invention; and

[0009] Figure 3 According to some embodiments of the present invention, Figure 1 A schematic diagram of the operation timing of the communication device. DETAILED DESCRIPTION

[0010] All terms used herein have their usual meanings. The above terms are usually defined in dictionaries, and any examples used in the context of the present invention that include any term discussed herein are only illustrative and do not limit the scope and meaning of the present invention. Similarly, the present invention is not limited to the various embodiments shown in this specification.

[0011] As used herein, "coupled" or "connected" may refer to two or more elements being in direct physical or electrical contact with each other, or being in indirect physical or electrical contact with each other, or may refer to two or more elements operating or acting on each other. As used herein, the term "circuit" may refer to a device composed of at least one transistor and / or at least one active / passive element connected in a certain manner to process signals.

[0012] As used herein, the term "and / or" includes any combination of one or more of the listed associated items. In this article, the words first, second, and third, etc. are used to describe and distinguish each element. Therefore, the first element in this article can also be referred to as the second element without departing from the original intention of the present invention. For ease of understanding, similar elements in the drawings will be designated with the same reference numerals.

[0013] Figure 1 is a schematic diagram of a communication device 100 drawn according to some embodiments of the present invention. In some embodiments, the communication device 100 may be, but is not limited to, a wireless communication device. The communication device 100 includes a receiver circuit system 110, a processor circuit 120, and a gain control circuit system 130. The receiver circuit system 110 may receive a communication signal SIN and transmit the received communication signal SIN to the processor circuit 120 and the gain control circuit system 130. In detail, the receiver circuit system 110 includes an analog front-end circuit 112 and a digital front-end circuit 114. The analog front-end circuit 112 may process the communication signal SIN according to a first gain (for example, an analog gain) to generate a digital signal D1. For example, the analog front-end circuit 112 may amplify the communication signal SIN based on the analog gain, filter the amplified communication signal SIN, and convert the processed signal into a digital signal D1. For example, the analog front-end circuit 112 may include, but is not limited to, a low noise amplifier circuit (not shown) for providing the analog gain (which is adjustable), a filter circuit (not shown), and an analog-to-digital converter circuit (not shown). The digital front-end circuit 114 is coupled to the analog front-end circuit 112 to receive the digital signal D1 and process the digital signal D1 according to a second gain (e.g., a digital gain) to obtain information carried by the communication signal SIN. In some embodiments, the digital front-end circuit 114 may include, but is not limited to, a digital filter circuit, a digital signal processor circuit, and the like.

[0014] The processor circuit 120 may execute (e.g., calculate) a delay correlation function according to a plurality of symbols in the communication signal SIN to determine whether the currently received communication signal SIN is valid. If the communication signal SIN is valid (e.g., the communication signal SIN conforms to the packet format in the predetermined communication protocol), the processor circuit 120 may generate a control signal SC having a first logic value to notify the gain control circuit system 130 to start executing the first gain control and the second gain control described later. In some embodiments, the aforementioned predetermined communication protocol may be, but not limited to, IEEE 802.15.4 or its related versions. If the communication signal SIN belongs to a valid packet in this communication protocol, the preamble of the communication signal SIN has 8 identical symbols. By analyzing these symbols using the delay correlation function, the processor circuit 120 may determine whether the currently received communication signal SIN is valid. If the results of the delay correlation function obtained according to these symbols all enable the processor circuit 120 to determine that the current communication signal SIN is valid, it means that the probability that the received communication signal SIN is valid is quite high. On the contrary, since noise or interference usually does not have multiple repeated symbol features, if the result of the delay correlation function obtained based on these symbols fails to enable the processor circuit 120 to determine that the current communication signal SIN is valid, it means that the currently received communication signal SIN is not valid. Figure 2 and Figure 3 Detailed description.

[0015] The gain control circuit system 130 may start to perform a first gain control and then perform a second gain control based on the control signal SC sent by the processor circuit 120 to adjust the analog gain and / or digital gain of the receiver circuit 120. For example, when the processor circuit 120 performs a first gain control based on at least one first symbol of the communication signal SIN (for example, but not limited to, Figure 3 When the processor circuit 120 determines that the communication signal SIN is valid based on the plurality of symbols P1-P3 in the communication signal SIN, the processor circuit 120 may issue a control signal SC having a first logic value. In response to the control signal SC, the gain control circuit system 130 starts to perform the first gain control. In other words, the gain control circuit system 130 may be activated when the processor circuit 120 determines that the communication signal SIN is valid based on the at least one first symbol, so as to increase the gain control value based on the at least one second symbol (for example, but not limited to, Figure 3The gain control circuit system 130 may continue to perform a first gain control to adjust the analog gain of the receiver circuit system 110 (e.g., the amplification gain of the analog front-end circuit 112) based on the symbol P4 in the communication signal SIN, wherein at least one second symbol is located after (follows) the at least one first symbol. Then, the gain control circuit system 130 may continue to perform a first gain control based on at least one third symbol of the communication signal SIN (e.g., but not limited to, Figure 3 A second gain control is performed on multiple symbols P5~P8 in the receiver circuit system 110 to adjust the digital gain of the receiver circuit system 110 (for example, the amplification gain of the digital front-end circuit 114), wherein at least one third symbol is located after (follows) the aforementioned at least one second symbol.

[0016] In some embodiments, the gain control circuit system 130 includes a gain control circuit 132 and a gain control circuit 134. The gain control circuit 132 is used to perform the aforementioned first gain control to adjust the analog gain of the receiver circuit system 110 (for example, the circuit setting of the amplifier in the analog front-end circuit 112 can be adjusted). In other words, the gain control circuit 132 can be an analog automatic gain control (AAGC) circuit. In some embodiments, the gain control circuit 132 can compare the signal strength of the currently received communication signal SIN with the first reference signal strength. If the signal strength of the currently received communication signal SIN is lower than the first reference signal strength, the gain control circuit 132 can increase the analog gain of the receiver circuit system 110. Alternatively, if the signal strength of the currently received communication signal SIN is higher than the first reference signal strength, the gain control circuit 132 can reduce the analog gain of the receiver circuit system 110. By repeating the above operation, the analog gain of the receiver circuit system 110 can be adaptively (in real time) adjusted according to the signal strength of the received communication signal SIN to obtain better signal quality. In some embodiments, the gain control circuit 132 may be implemented by a feedback control circuit that can perform the operations described above.

[0017] The gain control circuit 134 is used to perform the aforementioned second gain control to adjust the digital gain of the receiver circuit system 110 (for example, the circuit settings of the analog-to-digital converter in the analog front-end circuit 112, the circuit settings of the digital front-end circuit 114, and / or related parameters in the signal processing algorithm can be adjusted). In other words, the gain control circuit 134 can be a digital automatic gain control (DAGC) circuit. In some embodiments, the gain control circuit 134 can compare the signal strength of the digital signal D1 with the second reference signal strength. If the signal strength of the digital signal D1 is lower than the second reference signal strength, the gain control circuit 134 can increase the digital gain of the receiver circuit system 110. Alternatively, if the signal strength of the digital signal D1 is higher than the second reference signal strength, the gain control circuit 134 can reduce the digital gain of the receiver circuit system 110. In this way, the gain control circuit 134 can keep the signal strength of the digital signal D1 within a range suitable for subsequent signal processing. In some embodiments, the gain control circuit 134 can be implemented by a feedback control circuit that can perform the above operations.

[0018] In some embodiments, after the gain control circuit system 130 is activated to perform the first gain control, the processor circuit 120 may continue to calculate the delay correlation function according to multiple symbols of the communication signal SIN to continuously detect whether the communication signal SIN is valid. In other words, during the process of the gain control circuit 132 (and / or the gain control circuit 134) performing the first gain control (and / or the second gain control), the processor circuit 120 still continues to calculate the delay correlation function to continuously detect whether the communication signal SIN is valid. If it is detected that the communication signal SIN is not valid, it means that the received communication signal SIN may be noise or interference. Under this condition, the processor circuit 120 may send a control signal SC with a second logic value to stop the first gain control (and / or the second gain control) and stop processing the communication signal SIN.

[0019] In other embodiments, the communication device 100 includes a monitoring circuit (not shown) that can continuously monitor the result generated by the processor circuit 120 according to the delay correlation function, and stop the first gain control (and / or the second gain control) when it is determined that the communication signal SIN is invalid, and stop processing the communication signal SIN. In some embodiments, the function of the aforementioned monitoring circuit can be integrated into the processor circuit 120, but the present invention is not limited to this. In the aforementioned embodiments, the first gain control is AAGC, and the second gain control is DAGC, but the present invention is not limited to this. In other embodiments, the first gain control may be DAGC, and the second gain control may be AAGC.

[0020] The aforementioned operations of AAGC and DAGC are only for example, and the present invention is not limited thereto. Various gain control mechanisms that can be used to adjust the analog gain and digital gain of the receiver circuit are within the scope of the present invention.

[0021] Figure 2 FIG. 2 is a flow chart of a valid signal detection method 200 according to some embodiments of the present invention. In some embodiments, multiple operations of the valid signal detection method 200 may be performed by Figure 1 The communication device 100 is executed, but the present invention is not limited to this.

[0022] In operation S210, a communication signal is received via a receiver circuit system, wherein the communication signal includes a plurality of symbols. Figure 1 The receiver circuit system 110 in can receive the communication signal SIN.

[0023] In operation S220, a delay correlation function is calculated based on the multiple symbols. In operation S230, it is determined whether the communication signal is valid. If the communication signal is determined to be valid, operations S240 and S250 are performed. Alternatively, if the communication signal is not determined to be valid, operation S220 is performed again. For example, the processor circuit 120 may calculate the delay correlation function described later based on the currently received symbol, and determine whether the currently received symbol meets the relevant requirements in the predetermined communication protocol based on the calculation result to confirm whether the currently received communication signal SIN is valid. If the currently received communication signal SIN is not valid, the processor circuit 120 will continue to detect whether the subsequently received communication signal SIN is valid (i.e., operation S220).

[0024] To facilitate understanding of operations S220 and S230, a mathematical model of a delay correlation function is described below (but the present invention is not limited thereto). In some embodiments, the delay correlation function can be expressed as the following formula (1):

[0025]

[0026] Among them, r i,n is the i-th antenna (not shown) of the communication device 100 Figure 1 ) is the communication signal SIN received at the nth time point, and τ is the period of a preamble code. In formula (1), the communication signal SIN is represented as a complex number with a real part and an imaginary part (i.e., r i,n ), which contains information about the signal amplitude and phase, which is easy to understand for those skilled in the art, so it will not be described in detail. In addition, For r i,n-τ The complex conjugate of .

[0027] The processor circuit 120 may calculate the delay correlation function of the communication signal SIN according to at least one first symbol in the communication signal SIN (for example, at least one of the multiple symbols of the communication signal SIN that is first received by the receiver circuit system 110) to determine the delay-related information (i.e., the calculation result of the delay correlation function). In some embodiments, the delay-related information may include a delay-related output value and / or a critical value. In detail, the processor circuit 120 may obtain an output value C(t) based on the delay correlation function of formula (1), accumulate the output value C(t), and calculate the square of the accumulated result to generate a delay-related output value. The above operation can be expressed as the following formula (2):

[0028]

[0029] Wherein, O1 is the first delay-related output value, and L is the time length. In some embodiments, the time length L can be set to the period of the symbol in the preamble defined in the predetermined communication protocol used by the communication device 100. For example, the aforementioned predetermined communication protocol can be IEEE 802.15.4, or a related version thereof. In this communication protocol, the preamble in the packet conforming to the valid signal contains 8 identical symbols, and the period of each symbol is 16 microseconds (μs). Under this condition, the time length L can be set to about 16 microseconds.

[0030] In some embodiments, the processor circuit 120 may obtain an output value C(t) based on the delay correlation function of equation (1), accumulate the square of the output value C(t), and calculate the square of the accumulated result to generate a critical value. The above operation can be expressed as the following equation (3):

[0031]

[0032] Among them, TH1 is the critical value.

[0033] After the processor circuit 120 obtains the delay correlation output value O1 and the threshold value TH1 based on the delay correlation function calculated by the at least one symbol, the processor circuit 120 may compare the delay correlation output value O1 and the threshold value TH1 to confirm whether the current communication signal SIN is valid. For example, if the delay correlation output value O1 is greater than the product of the threshold value TH1 and the time length L, the processor circuit 120 may determine that the current communication signal SIN is valid. Alternatively, if the delay correlation output value O1 is not greater than the threshold value TH1, the processor circuit 120 may determine that the current communication signal SIN is invalid.

[0034] Continue to refer to Figure 2In operation S240, a first gain control is performed to adjust a first gain of the receiver circuit system. For example, as described above, when the processor circuit 120 detects that the current communication signal SIN is valid, the processor circuit 120 may send a control signal SC to start the gain control circuit system 130 to start performing a first gain control according to at least one second symbol in the communication signal SIN to adjust the analog gain of the receiver circuit system 110.

[0035] In operation S250, the result generated based on the delay correlation function is monitored to confirm whether the communication signal is valid. If the communication signal SIN is still valid, operation S260 is performed. Alternatively, if the communication signal SIN is not valid, operation S270 is performed. In operation S260, the second gain control and subsequent signal receiving procedures are performed. In operation S270, the first gain control is stopped and the processing of the currently received communication signal is stopped.

[0036] For example, during the period when the gain control circuit system 130 performs the first gain control, the processor circuit 120 may continuously perform a plurality of operations S210, S220 and S230, and may continuously monitor the detection result generated by operation S230 (i.e., operation S250). Once the detection result generated in operation S230 indicates that the communication signal SIN is not valid, the processor circuit 120 may send a control signal SC to stop the gain control circuit system 130 to stop the first gain control (and / or the second gain control), and discard the currently received communication signal SIN to stop processing the currently received communication signal SIN. On the other hand, if the detection result generated in operation S230 continues to indicate that the communication signal SIN is valid, as described above, the gain control circuit system 130 may continue to perform the second gain control according to at least one third symbol of the communication signal SIN to adjust the digital gain of the receiver circuit system 110, and perform subsequent signal receiving procedures (e.g., including, but not limited to, correction of carrier frequency offset, baseband signal processing, etc.).

[0037] The multiple operations of the effective signal detection method 200 are only examples and are not limited to being performed in the order in this example. Without violating the operation mode and scope of each embodiment of the present invention, the various steps of the effective signal detection method 200 can be appropriately added, replaced, omitted or performed in a different order. Alternatively, one or more operations of the various steps of the effective signal detection method 200 can be performed simultaneously or partially simultaneously. For example, operation S240 and operation S250 can be performed simultaneously during the period when the gain control circuit system 130 performs the first gain control.

[0038] Figure 3 According to some embodiments of the present invention, Figure 1FIG. 1 is a schematic diagram of the operation timing of the communication device 100. In this example, it is assumed that the predetermined communication protocol used by the communication device 100 is IEEE 802.15.4, or a related version thereof. Therefore, if the communication signal SIN is valid, the packet format of the communication signal SIN should conform to the packet format defined in the predetermined communication protocol. For example, in the relevant specifications of IEEE 802.15.4, a valid packet includes a preamble, a start of frame delimiter, a frame length, and a physical layer service data unit (PSDU) in sequence. Figure 3 The leading code at the front of the packet format is shown, which includes 8 identical symbols P1-P8, and the period of each symbol P1-P8 is 16 microseconds (μs).

[0039] As described above, the processor circuit 120 may determine whether the communication signal SIN is valid according to at least one first symbol of the communication signal SIN, thereby starting the gain control circuit system 130. In some embodiments, the at least one first symbol may be at least one of the multiple symbols of the communication signal SIN that is first received by the receiver circuit system 110. For example, Figure 3 As shown, the processor circuit 120 can calculate the delay correlation function according to the multiple symbols P1-P3 (equivalent to the at least one first symbol mentioned above) to determine whether the communication signal SIN is valid (ie Figure 2 Then, if the communication signal SIN is determined to be valid, the gain control circuit system 130 may be activated and start to perform the first gain control (i.e., Figure 2 At the same time, the processor circuit 120 may continue to calculate the delay correlation function based on the subsequent multiple symbols P5-P8 to continuously determine whether the communication signal SIN is valid (ie Figure 2 The gain control circuit system 130 and / or the processor circuit 120 may continue to perform the second gain control and subsequent signal receiving procedures according to the remaining plurality of symbols P5-P8 (ie, Figure 2 Operation S260).

[0040] In some related technologies, when the communication device starts to receive a signal, if the symbol in the received signal satisfies the result obtained based on the delay correlation function (i.e., the communication device has determined that the currently received signal is valid), the communication device will no longer execute the delay correlation function. In the above-mentioned technology, the communication device needs to determine whether the signal is valid (i.e., confirm whether the detection result previously obtained based on the delay correlation function is correct) when the frame start delimiter of the signal is received. In the above-mentioned technology, if the currently received signal is actually noise or interference and the communication device misjudges the received signal as valid according to the delay correlation function, the communication device needs to perform a secondary detection when the frame start delimiter is received (e.g., after 8×16μs), so as to determine that the signal is not valid. In this way, the communication devices in these technologies cannot immediately receive other valid signals during the above-mentioned inspection period. Compared with the above-mentioned technology, in some embodiments of the present invention, after executing the first gain control, the processor circuit 120 continues to calculate the delay correlation function (and continues to monitor the result obtained based on the delay correlation function) to determine whether the communication signal SIN is valid. Since the valid communication signal SIN has a long-term repetitive feature (i.e., 8 identical symbols P1-P8), the processor circuit 120 can continuously calculate the delay correlation function for these symbols P1-P8 during the preamble period to determine whether the communication signal SIN is valid. In this way, the communication device 100 can perform several detections before receiving the frame start delimiter to avoid misjudgment, and accordingly discard the current communication signal SIN (if it is detected that the communication signal SIN is not valid) to start receiving the next communication signal SIN more quickly. At the same time, the gain control circuit system 130 can perform the original operation during the detection period of the processor circuit 120, so the above-mentioned valid signal detection method will not affect the operating efficiency of other circuits in the communication device 100.

[0041] Figure 3 The correspondence between the multiple symbols P1~P8 shown and the aforementioned at least one first symbol, at least one second symbol and at least one third symbol is not limited to the aforementioned examples. It should be understood that in different embodiments, the number of symbols in the at least one first symbol may be one or more symbols in the multiple symbols P1~P8, the number of symbols in the at least one second symbol may be one or more symbols in the multiple symbols P1~P8, and the number of symbols in the at least one third symbol may be one or more symbols in the multiple symbols P1~P8. In other words, in different embodiments, at least one first symbol, at least one second symbol and at least one third symbol may be the same, partially the same or completely different (for example, Figure 3In some embodiments, there may be other symbols between at least one second symbol and at least one first symbol, and there may be other symbols between at least one third symbol and at least one second symbol. In other words, in different embodiments, at least one second symbol may directly or indirectly follow at least one first symbol, and at least one third symbol may directly or indirectly follow at least one second symbol. In some embodiments, the execution period of the valid signal detection method 200 may be a portion of the preamble period. In some embodiments, the execution period of the valid signal detection method 200 may be the same as the preamble period. In other words, the communication device 100 may execute the aforementioned valid signal detection method 200 based on a portion of the multiple symbols P1 to P8, or execute the aforementioned valid signal detection method 200 based on all the symbols P1 to P8.

[0042] The delay correlation function, delay correlation output value O1, and mathematical model and / or related definition of the critical value TH1 provided in the above embodiments are only used for examples, and the present invention is not limited thereto. In some embodiments, antenna weight parameters, critical value correction parameters, etc. may be added to the delay correlation function. Various delay correlation functions and delay related information that can be used for signal detection are within the scope of the present invention.

[0043] On the other hand, the packet forms and the types of predetermined communication protocols provided in the above-mentioned various embodiments are only examples, and the present invention is not limited thereto. Various predetermined communication protocols that use packets with (long-term or certain-time) repetitive characteristics for transmission all belong to the scope covered by the present invention. For example, in some embodiments, the predetermined communication protocol may also be multiple versions of IEEE802.11.

[0044] In summary, the communication device and valid signal detection method provided by some embodiments of the present invention can utilize the delay correlation function to continuously monitor whether the currently received communication signal is interference, thereby discarding invalid signals more quickly and starting to receive new signals.

[0045] Although the embodiments of the present invention are described above, these embodiments are not intended to limit the present invention. Ordinary technicians with common knowledge in the technical field can modify and change the technical features of the present invention based on the explicit or implicit contents of the present invention. These modifications are all within the scope of protection of the present invention. In other words, the scope of patent protection of the present invention shall be based on the scope of the claims of this application.

[0046] Description of Reference Numerals

[0047] 100:Communication device

[0048] 110: Receiver circuit system

[0049] 112:Analog front-end circuit

[0050] 114: Digital front-end circuit

[0051] 120: Processor circuit

[0052] 130: Gain control circuit system

[0053] 132,134: Gain control circuit

[0054] 200: Effective signal detection method

[0055] D1: Digital signal

[0056] P1~P8: Symbol

[0057] S210,S220,S230,S240,S250,S260,S270: Operation

[0058] SC: Control signal

[0059] SIN: communication signal

Claims

1. A communication device, comprising: a receiver circuit system for receiving a communication signal, wherein the communication signal comprises a plurality of symbols; A processor circuit, configured to calculate a delay correlation function based on the plurality of symbols to determine whether the communication signal is valid; and a gain control circuit system for starting, when the processor circuit determines that the communication signal is valid based on at least one first symbol of the plurality of symbols, to perform a first gain control to adjust a first gain of the receiver circuit system based on at least one second symbol of the plurality of symbols, The at least one second symbol follows the at least one first symbol, and when the processor circuit determines that the communication signal is not valid according to the delay correlation function, the processor circuit stops the first gain control and stops processing the communication signal.

2. The communication device of claim 1 , wherein the receiver circuitry comprises: an analog front end circuit, configured to receive the communication signal and process the communication signal according to the first gain to generate a digital signal; and The digital front end circuit is used to process the digital signal according to the second gain.

3. The communication device of claim 2, wherein the gain control circuit system is further configured to perform a second gain control to adjust the second gain based on at least one third symbol among the plurality of symbols, and the at least one third symbol follows the at least one second symbol.

4. The communication device according to claim 3, wherein when the processor circuit determines that the communication signal is not valid according to the delay correlation function, the processor circuit stops the second gain control and stops processing the communication signal. 5 . The communication device of claim 3 , wherein the first gain control is an analog gain control and the second gain control is a digital gain control. 6 . The communication device of claim 1 , wherein the at least one first symbol is at least one of the plurality of symbols that is received first by the receiver circuitry. 7 . The communication device of claim 1 , wherein after the gain control circuit system starts to perform the first gain control, the processor circuit continues to calculate the delay correlation function to determine whether the communication signal is valid. 8 . The communication device of claim 1 , wherein the plurality of symbols are included in a preamble, and the preamble complies with communication protocol IEEE 802.15.

4.

9. The communication device according to claim 1, wherein the plurality of symbols are identical to each other.

10. An effective signal detection method, comprising: receiving, via receiver circuitry, a communication signal, wherein the communication signal comprises a plurality of symbols; Calculate a delay correlation function according to the plurality of symbols to determine whether the communication signal is valid; as well as When the communication signal is determined to be valid based on at least one first symbol of the plurality of symbols, performing a first gain control to adjust a first gain of the receiver circuit system based on at least one second symbol of the plurality of symbols, wherein the at least one second symbol follows the at least one first symbol; as well as When it is determined according to the delay correlation function that the communication signal is not valid, the first gain control is stopped and the processing of the communication signal is stopped.

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