CN107846229A - Apparatus and method for processing symbol rate estimation and interference - Google Patents

Abstract

An apparatus and method for processing symbol rate estimation and interference. The invention relates to a communication device, comprising a receiving circuit, a receiving circuit and a processing circuit, wherein the receiving circuit is used for receiving a plurality of time domain signals; a conversion circuit, coupled to the receiving circuit, for converting the plurality of time domain signals into a plurality of frequency domain signals according to a time-frequency conversion operation; an amplitude circuit, coupled to the converting circuit, for performing an absolute value operation on the plurality of frequency domain signals, respectively, to generate a plurality of output signals; and a selection circuit, coupled to the magnitude circuit, for selecting a maximum signal satisfying a detection condition from the plurality of output signals.

Description

Apparatus and method for processing symbol rate estimation and interference

technical field

The invention relates to an apparatus and method for a communication system, especially to an apparatus and method for processing symbol rate estimation and interference.

Background technique

In order to evaluate the performance of the system or configure the configuration of the receiving end, the receiving end often needs to estimate the symbol rate accurately. However, when the signal is transmitted through the channel, it will be affected by the channel effect, such as interference such as co-channel interference, which makes it difficult for the receiving end to accurately estimate the symbol rate, and then erroneously evaluate the system performance or Set the configuration of the receiver.

In addition, in order to mitigate the impact of interference, the receiving end should know the frequency location of the interference to avoid or eliminate the interference. However, due to negative effects such as noise, it is difficult for the receiving end to accurately estimate the frequency position of the interference.

Therefore, how to accurately estimate the symbol rate and the frequency position of the interference under the influence of the channel effect is an extremely important issue.

Contents of the invention

Therefore, the present invention provides an apparatus and method for processing symbol rate estimation, which can obtain accurate symbol rates while saving power consumption and shortening locking time, so as to solve the above-mentioned problems.

The present invention discloses a communication device, comprising a receiving circuit for receiving a first plurality of time-domain signals; a conversion circuit coupled to the receiving circuit for operating according to a time-frequency conversion to convert the first plurality of time domain signals The domain signal is converted into a first plurality of frequency domain signals; a magnitude circuit, coupled to the conversion circuit, is used to respectively perform an absolute value operation on the first plurality of frequency domain signals to generate a first plurality of output signals and a selection circuit, coupled to the magnitude circuit, for selecting a maximum signal satisfying a detection condition from the first plurality of output signals.

The present invention also discloses using a receiving circuit to receive the first plurality of time-domain signals; using a calculation circuit to convert the first plurality of time-domain signals into the first plurality of frequency-domain signals according to a time-frequency conversion operation; using a A magnitude circuit is used to perform an absolute value operation on the first plurality of frequency domain signals respectively to generate a first plurality of output signals; and a selection circuit is used to select a detection condition from the first plurality of output signals a maximum signal of .

Description of drawings

FIG. 1 is a schematic diagram of a communication system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an estimation module according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a communication device according to Embodiment 1 of the present invention.

FIG. 4 is a schematic diagram of a communication device according to Embodiment 1 of the present invention.

FIG. 5 is a schematic diagram of the operation of a communication device according to an embodiment of the present invention.

FIG. 6 is a flow chart of a process in Embodiment 1 of the present invention.

FIG. 7 is a schematic diagram of an estimation circuit according to an embodiment of the present invention.

Symbol Description

10 communication system

20 Estimation Module

200 receiving circuit

202 conversion circuit

204 magnitude circuits

206 select circuit

30, 40 Communication device

300 bandwidth estimation circuit

302 computing circuits

40 Interference Estimation Circuit

60 process

600, 602, 604, 606, 608, steps

610, 612

70 Estimation circuit

700 scratchpad

710 Adding circuit

720 sliding window circuit

722, 724 comparators

726 AND gate

sig_t1～sig_tP time domain signal

sig_f1～sig_fP frequency domain signal

sig_f_out1～sig_f_outP output signal

sig_f_max maximum signal

bw_est bandwidth

sbr_est symbol rate

TX transmitter

RX receiver

Detailed ways

FIG. 1 is a schematic diagram of a communication system 10 according to an embodiment of the present invention. The communication system 10 can be any communication system capable of transmitting and/or receiving single-carrier signals or multi-carrier signals, and is simply composed of a transmitting end TX and a receiving end RX. The multi-carrier signal may be an orthogonal frequency-division multiplexing (OFDM) signal (or a discrete multi-tone modulation (DMT) signal), but is not limited thereto. In FIG. 1 , the transmitting end TX and the receiving end RX are used to illustrate the architecture of the communication system 10 . For example, the communication system 10 can be an asymmetric digital subscriber line (asymmetric digital subscriber line, ADSL) system, a power line communication (power line communication, PLC) system, an Ethernet over coaxial cable (Ethernet over coax, EOC) and other wired communication systems. Alternatively, the communication system 10 may be a wireless communication system such as a wireless local area network (WLAN), a digital video broadcasting (Digital Video Broadcasting, DVB) system, and an advanced long-term evolution (Long Term Evolution-advanced, LTE-A) system. , where the digital video broadcasting system can include terrestrial digital multimedia broadcasting (Digital Terrestrial MultimediaBroadcast, DTMB), terrestrial digital video broadcasting system (DVB-Terrestrial, DVB-T), the new version of terrestrial digital video broadcasting system (DVB-T2/C2) and Integrated Digital Services Broadcasting System (Integrated Services DigitalBroadcasting, ISDB). In addition, the transmitting end TX and the receiving end RX can be set in devices such as mobile phones, notebook computers, tablet computers, e-books, and portable computer systems, but are not limited thereto.

FIG. 2 is a schematic diagram of an estimation module 20 according to an embodiment of the present invention, which is used in the receiving end RX of FIG. 1 and can be used to estimate the bandwidth of the received signal or the frequency position of the interference. The estimation module 20 includes a receiving circuit 200 , a conversion circuit 202 , a magnitude circuit 204 and a selection circuit 206 . In detail, after receiving a plurality of time-domain signals sig_t1, the receiving circuit 200 provides the plurality of time-domain signals sig_t1 to the converting circuit 202 . Wherein, the plurality of time domain signals sig_t1 can be implemented by performing 16 quadrature amplitude modulation (quadrature amplitude modulation, QAM), 32 quadrature amplitude modulation, 64 quadrature amplitude modulation, 128 quadrature amplitude modulation or 256 quadrature amplitude modulation, etc. Signals generated by modulation operations, but not limited to. The conversion circuit 202 is coupled to the receiving circuit 200 and is configured to convert a plurality of time-domain signals sig_t1 into a plurality of frequency-domain signals sig_f1 according to a time-frequency conversion operation. Wherein, the time-frequency conversion operation may be an algorithm such as Fast Fourier Transform (FFT), which can convert a time-domain signal into a frequency-domain signal, but is not limited thereto. The magnitude circuit 204 is coupled to the conversion circuit 202 and can be used to perform an absolute value operation on the frequency-domain signals sig_f1 (ie obtain the absolute values of the frequency-domain signals sig_f1 respectively) to generate a plurality of output signals sig_f_out1 .

In addition, the receiving circuit 200 can additionally receive a plurality of time domain signals sig_t2. Similarly, the conversion circuit 202 operates according to the time-frequency conversion, and converts the plurality of time-domain signals sig_t2 into a plurality of frequency-domain signals sig_f2. The magnitude circuit 204 respectively performs absolute value operations on the multiple frequency domain signals sig_f2 (ie respectively obtains the absolute values of the multiple frequency domain signals sig_f2 ) to generate multiple output signals sig_f_out2 . The selection circuit 206 can correspondingly add a plurality of output signals sig_f_out1 and a plurality of output signals sig_f_out2 to generate a plurality of auxiliary signals sig_f_aux. The above operation can be repeated for a preset number of times, that is, the output signal is superimposed to the preset number of times.

Next, the selection circuit 206 can select a maximum signal sig_f_max satisfying a detection condition from the plurality of auxiliary signals sig_f_aux (or from the plurality of output signals sig_f_out1 if no superposition is performed). Wherein, the maximum signal sig_f_max has a maximum amplitude satisfying the detection condition. According to the above, in the process of searching for the maximum signal, the selection circuit 206 will not only consider the magnitude of the signal amplitude, but also consider whether the signal meets the detection conditions, and reduce negative effects (such as noise and/or interference) through the detection conditions. ) to improve the reliability of the selected signal.

FIG. 3 is a schematic diagram of a communication device 30 according to an embodiment of the present invention, which is used in the receiving end RX of FIG. 1 to estimate the symbol rate of the received signal. The communication device 30 includes an estimation module 20 , a bandwidth estimation circuit 300 and a calculation circuit 302 . The bandwidth estimation circuit 300 is coupled to the estimation module 20, and can be used to estimate the bandwidth according to the maximum signal sig_f_max and the minimum output signal sig_f_min among the multiple auxiliary signals sig_f_aux (if not superimposed, among the multiple output signals sig_f_out1) bw_est. Since the selected maximum signal sig_f_out has higher reliability, the accuracy of the bandwidth bw_est can be improved. The calculation circuit 300 is coupled to the bandwidth estimation circuit 300 and can be used to calculate the symbol rate sbr_est according to the bandwidth bw_est. As mentioned earlier, the bandwidth bw_est has high accuracy, and correspondingly, the symbol rate sbr_est obtained according to the bandwidth bw_est also has high accuracy, so that the receiving end RX can accurately evaluate according to the symbol rate sbr_est System performance or setting receiver configuration. According to the definition of the symbol rate sbr_est, there are different correspondences between the bandwidth bw_est and the symbol rate sbr_est. For example, when the bandwidth bw_est is the same (or similar) to the symbol rate sbr_est, the calculation circuit 300 can directly output the bandwidth bw_est as the symbol rate sbr_est. At this time, the bandwidth estimation circuit 300 and the calculation circuit 302 can be integrated into a single circuit. When there is a large difference between the bandwidth bw_est and the symbol rate sbr_est, those skilled in the art can design or modify the calculation circuit 300 accordingly to obtain a defined symbol rate.

FIG. 4 is a schematic diagram of a communication device 40 according to an embodiment of the present invention, which is used in the receiving end RX of FIG. 1 to determine a frequency position of interference. The communication device 40 includes an estimation module 20 and an interference estimation circuit 400 . The interference estimation circuit 400 is coupled to the estimation module 20 and can be used to determine a frequency position loc_f of the maximum signal. Since the selected maximum signal sig_f_out has higher reliability, the accuracy of the frequency position loc_f can be improved.

It should be noted that there are many methods for the selection circuit 206 to select the maximum signal. For example, the selection circuit 206 can use a window to sequentially output signals from multiple groups of multiple output signals sig_f_out1 (or multiple auxiliary signals sig_f_aux obtained after superposition) according to a sliding window method. Select the largest signal that meets the detection conditions. Further, there are many detection conditions that can be used to judge the reliability of the signal.

In one embodiment, when the selection circuit 206 is used for estimating the bandwidth, one set of output signals among the multiple sets of output signals can satisfy the detection condition according to the following equation:

in is the group of output signals, M is a size of the window, f(·) is a function, sub_max is an index of a maximum signal of the group of output signals, and G is a positive real number. Preferably, G is a gain margin. That is to say, G*Z _{sub_max} cannot be judged as meeting the detection condition until it is too large. G is a design value or a predetermined value, which can be determined according to system considerations and design requirements. For example, when the requirement on reliability is higher, G can be set as a larger positive real number, that is, the maximum signal Z _{sub_max} is less likely to be satisfied (Formula 1). Conversely, when the reliability requirement is low, G can be set as a small positive real number, that is, the maximum signal Z _{sub_max is} easier to satisfy (Formula 1).

In another embodiment, when the selection circuit 206 is used for estimating interference, one set of output signals among multiple sets of output signals may satisfy the detection condition according to the following equation:

in is the group of output signals, M is a size of the window, f(·) is a function, sub_max is an index of a maximum signal of the group of output signals, and G is a positive real number. Preferably, G is a gain margin. That is to say, G*Z _{sub_max} needs to be large enough to be judged as meeting the detection condition. G is a design value or a predetermined value, which can be determined according to system considerations and design requirements. For example, when the requirement on reliability is higher, G can be set as a small positive real number, that is, the maximum signal Z _{sub_max} is less likely to be satisfied (Formula 2). Conversely, when the reliability requirement is low, G can be set as a larger positive real number, that is, the maximum signal Z _{sub_max is} easier to satisfy (Formula 2).

It should be noted that, in the above embodiments, the functions in (Formula 1) and (Formula 2) can be the following equations:

That is, (Formula 1) and (Formula 2) represent that G*Z _{sub_max} needs to be greater than all The sum will be judged to meet the detection conditions. In addition (Equation 1) ~ (Equation 3) only illustrate the way of selecting the largest signal in a group of output signals, the selection circuit 206 should be based on the sliding window method, for multiple output signals sig_f_out1 (or multiple auxiliary signals obtained after accumulation) (Equation 1) to (Equation 3) are repeated for all groups of output signals in the signal sig_f_aux) to select the maximum signal sig_f_max.

FIG. 5 is a schematic diagram of the operation of a communication device 30 according to an embodiment of the present invention, which is used to illustrate the operation of the communication device 30 . In FIG. 5 , the receiving circuit 200 receives multiple time-domain signals sig_t1(x _1,1 , . . . , x _1,N ), where N is the size of the FFT. Next, the conversion circuit 202 converts multiple time-domain signals sig_t1(x _1,1 ,...,x _1,N ) into multiple frequency-domain signals sig_f1(Y _1,1 ,..., _1,N according to the time-frequency conversion operation ). The magnitude circuit 204 performs absolute value operations on multiple frequency domain signals sig_f1(Y _1,1 ,...,Y _1,N ) respectively to generate multiple output signals sig_f_out1(Z _1,1 ,...,Z _1,N ) , that is, Z _1,k =|Y _1,k |,k=1,...,N. The communication device 30 can perform superposition according to the setting conditions of the user, and the operation is as follows. The receiving circuit 200 continues to receive multiple time-domain signals sig_t2(x _2,1 , . . . , x _2,N ). Next, the conversion circuit 202 converts multiple time-domain signals sig_t2(x _2,1 ,...,x _2,N ) into multiple frequency-domain signals sig_f2(Y _2,1 ,...,Y _{2, N} ). The magnitude circuit 204 respectively performs an absolute value operation on a plurality of frequency domain signals sig_f2 (Y _2,1 ,...,Y _2,N ) to generate a plurality of output signals sig_f_out2 (Z _2,1 ,...,Z _2,N ) , ie Z _2,k =|Y _2,k |,k=1,...,N. The selection circuit 206 correspondingly adds a plurality of output signals sig_f_out1(Z _1,1 ,...,Z _1,N ) and a plurality of output signals sig_f_out2(Z _2,1 ,...,Z _2,N ) to generate a plurality of auxiliary signals sig_f_aux(A ₁ ,…,A _N ), namely The selection circuit 206 sequentially selects a plurality of maximum signals sig_f_max satisfying the detection condition from the plurality of auxiliary signals sig_f_aux (A ₁ , . . . , A _N ) according to the sliding window method. In order to clearly describe this embodiment to understand the concept of the present invention, this embodiment assumes that the detection conditions used are (Formula 1) and (Formula 3).

For example, the size of the window used by the selection circuit 206 is 4 (that is, M in (Formula 1) is 4), and a maximum signal is first selected from the auxiliary signals A ₁ , . . . , A ₄ , such as the auxiliary signal _A2 . Next, the selection circuit 206 _checks whether A2 satisfies As mentioned above, G is a positive real number, which can be determined according to system considerations and design requirements. If the auxiliary signal A ₂ satisfies the detection condition, the selection circuit 206 regards the auxiliary signal A ₂ as the maximum effective signal for estimating the bandwidth, and stores it in the estimation module 20 . According to the sliding window method, the selection circuit ₂₀₆ continues to select a maximum signal from the auxiliary signals _{A 2 ,} . Next, the selection circuit 206 checks whether the auxiliary signal A ₄ satisfies the condition A ₄ >A ₂ . If this condition is satisfied, the temporarily stored maximum signal is updated to be the auxiliary signal A ₄ . Next, go ahead and check If the auxiliary signal _A4 satisfies the detection condition, the bandwidth estimated according to the maximum value will be judged to be valid. If the auxiliary signal _A4 does not satisfy the detection condition, the bandwidth estimated according to the maximum value will be judged as invalid. If the auxiliary signal A ₄ does not satisfy the condition of A ₄ >A ₂ , then keep the temporarily stored maximum signal as the auxiliary signal A ₂ , and maintain the status of the wave bandwidth estimated according to the auxiliary signal A ₂ being valid or invalid. The selection circuit 206 continues the above operations until the auxiliary signals _AN-3 , . . . , _AN are processed.

After performing the above operations, if the maximum signal satisfies the detection condition, it is determined that the bandwidth estimated based on the maximum signal is valid, for example, the auxiliary signal A _max , and the bandwidth estimation circuit 300 can estimate the frequency according to the output signal A _max The width bw_est, and the calculating circuit 302 can calculate the symbol rate sbr_est according to the bandwidth bw_est.

The operation of the communication device 40 is similar to that of the communication device 30, the main difference is that the bandwidth estimation circuit 300 and the calculation circuit 302 are replaced by the interference estimation circuit 400, for example, the operations related to (Formula 1) and (Formula 3) are replaced Since the operations related to (Formula 2) and (Formula 3) are omitted here.

According to the aforementioned embodiments, the operation mode of the estimation module 20 can be summarized as a process 60 of the first embodiment of the present invention, which is used in the communication device 30 or the communication device 40 , as shown in FIG. 6 . Process 60 comprises the following steps:

Step 600: start.

Step 602: Receive multiple time-domain signals.

Step 604: Convert the multiple time-domain signals into multiple frequency-domain signals according to a time-frequency conversion operation.

Step 606: Perform an absolute value operation on the multiple frequency domain signals respectively to generate multiple output signals.

Step 608: If there are multiple previous output signals previously received, superimpose the multiple output signals and the multiple previous output signals into multiple auxiliary signals. If the number of superimpositions is equal to the preset number, go to step 610 ; if not, go to step 602 .

Step 610: Select a maximum signal satisfying a detection condition from the plurality of auxiliary signals.

Step 612: end.

The process 60 is used to illustrate the operation of the estimating module 20 with an example. For detailed description and changes, please refer to the above, and will not be repeated here.

It should be noted that the estimation module 20 (and the receiving circuit 200, the conversion circuit 202, the magnitude circuit 204 and the selection circuit 206), the communication device 30 (the estimation module 20, the bandwidth estimation circuit 300 and the calculation circuit 302 ) and the communication device 40 (estimation module 20 and interference estimation circuit 400) can be implemented in many ways. For example, according to design considerations or system requirements, the above-mentioned circuits can be integrated into one or more circuits, and in practice, digital circuits are usually implemented. In some embodiments, the receiving circuit 200 may further include an analog-to-digital converter. In addition, the evaluation module 20, the communication device 30 and the communication device 40 can be hardware, software, firmware (a combination of hardware devices and computer instructions and data, and the computer instructions and data belong to read-only software on the hardware device), electronic systems, Or a combination of the above devices to achieve, not limited thereto.

FIG. 7 is a schematic diagram of an estimation circuit 70 according to an embodiment of the present invention, which is used to realize the estimation module 20 . The estimation circuit 70 includes a plurality of registers 700 , an adding circuit 710 , a sliding window circuit 720 and a value updating circuit 730 . In detail, the multiple registers 700 can be used to receive multiple sets of time domain signals sig_t1˜sig_tP, and sequentially output multiple sets of time domain signals sig_t1˜sig_tP. The adding circuit 710 is coupled to a plurality of registers 700 and can be used to add a plurality of sets of time domain signals sig_t1˜sig_tP to obtain a plurality of auxiliary signals sig_f_aux. The sliding window circuit 720 is coupled to the adding circuit 710, and can be used to sequentially select the largest signal satisfying the detection condition (such as A ₂ , A ₄ , etc. ). The value update circuit 730 is coupled to the sliding window circuit 720 for receiving and comparing the maximum signal output by the sliding window circuit 720 . When the received maximum signal (such as A ₄ in the previous example) is greater than the current maximum signal (such as A ₂ in the previous example), the value updating circuit 730 replaces the current maximum signal with the received maximum signal. Conversely, when the received maximum signal is smaller than the current maximum signal, the value update circuit 730 maintains the current maximum signal time. After the estimation circuit 70 finishes processing the received values, the value update circuit 730 can obtain the maximum signal sig_f_max (eg A _max in the previous example).

In one embodiment, the sliding window circuit 720 may include a comparator 722 , a comparator 724 and an AND gate 726 . In detail, the comparator 722 can be used to compare a group of auxiliary signals (such as A ₁ , . . . , A ₄ in the previous example) to obtain the maximum signal (such as A ₂ ) in the group of auxiliary signals. The comparator 722 can be used to check whether the maximum signal satisfies the detection condition (such as (Formula 1) or (Formula 2) in the previous example). The AND gate 726 is coupled to the comparator 722 and the comparator 724 for outputting the maximum signal to the value update circuit 730 when the maximum signal satisfies the detection condition.

In summary, the present invention provides a device and method for processing symbol rate estimation and interference, which can stop receiving and processing additional time-domain signals according to whether the (maximum) signal meets the detection conditions, not only can obtain accurate The symbol rate and the frequency position of the interference also reduce unnecessary power consumption and shorten the latching time, which solves the problem that the known communication device needs to process excessive and unnecessary time-domain signals.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (20)

1. A communication device, comprising: A receiving circuit, used for receiving the first plurality of time-domain signals; a conversion circuit, coupled to the receiving circuit, for converting the first plurality of time-domain signals into the first plurality of frequency-domain signals according to a time-frequency conversion operation; a magnitude circuit, coupled to the conversion circuit, for performing an absolute value operation on the first plurality of frequency-domain signals respectively to generate a first plurality of output signals; and A selection circuit, coupled to the magnitude circuit, is used for selecting a maximum signal satisfying a detection condition from the first plurality of output signals. 2. The communication device according to claim 1, further comprising: a bandwidth estimation circuit, coupled to the selection circuit, for estimating a bandwidth according to the maximum signal and a minimum output signal among the first plurality of output signals; and A calculation circuit, coupled to the bandwidth estimation circuit, is used to calculate a symbol rate according to the bandwidth. 3. The communication device according to claim 1, further comprising: An interference estimation circuit, coupled to the selection circuit, is used to determine a frequency position of the maximum signal. 4. The communication device according to claim 1, wherein when the first plurality of output signals does not include the maximum signal satisfying the detection condition, the communication device performs the following operations: The receiving circuit receives a second plurality of time-domain signals; the conversion circuit operates according to the time-frequency conversion to convert the second plurality of time-domain signals into a second plurality of frequency-domain signals; the magnitude circuit performs the absolute value operation on the second plurality of frequency domain signals, respectively, to generate a second plurality of output signals; and The selection circuit correspondingly adds the first plurality of output signals and the second plurality of output signals to generate a plurality of auxiliary signals, and selects the maximum signal from the plurality of auxiliary signals and judges whether the maximum signal satisfies the Detection conditions. 5. The communication device according to claim 1, wherein the selection circuit sequentially selects the maximum signal from a plurality of output signals of the first plurality of output signals with a window according to a sliding window method , and check whether the maximum signal satisfies the detection condition. 6. The communication device according to claim 5, wherein one group of output signals in the multiple groups of output signals satisfies the detection condition according to the following equation: <mrow><mi>f</mi><mrow><mo>(</mo><msubsup><mrow><mo>{</mo><msub><mi>Z</mi><mi>k</mi></msub><mo>}</mo></mrow><mrow><mi>k</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>&amp;NotEqual;</mo><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow><mi>M</mi></msubsup><mo>)</mo></mrow><mo>+</mo><msub><mi>Z</mi><mrow><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>&gt;</mo><mi>G</mi><mo>*</mo><msub><mi>Z</mi><mrow><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>;</mo></mrow> in is the group of output signals, M is a size of the window, f(·) is a function, sub_max is an index of a maximum signal of the group of output signals, and G is a positive real number. 7. The communication device according to claim 6, wherein the function is the following equation: <mrow><mi>f</mi><mrow><mo>(</mo><msubsup><mrow><mo>{</mo><msub><mi>Z</mi><mi>k</mi></msub><mo>}</mo></mrow><mrow><mi>k</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>&amp;NotEqual;</mo><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow><mi>M</mi></msubsup><mo>)</mo></mrow><mo>=</mo><msubsup><mo>&amp;Sigma;</mo><mrow><mi>k</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>&amp;NotEqual;</mo><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>max</mi></mrow><mi>M</mi></msubsup><msub><mi>Z</mi><mi>k</mi></msub><mo>.</mo></mrow> 8. The communication device according to claim 5, wherein one group of output signals in the multiple groups of output signals satisfies the detection condition according to the following equation: <mrow><mi>f</mi><mrow><mo>(</mo><msubsup><mrow><mo>{</mo><msub><mi>Z</mi><mi>k</mi></msub><mo>}</mo></mrow><mrow><mi>k</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>&amp;NotEqual;</mo><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow><mi>M</mi></msubsup><mo>)</mo></mrow><mo>+</mo><msub><mi>Z</mi><mrow><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>&lt;</mo><mi>G</mi><mo>*</mo><msub><mi>Z</mi><mrow><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>;</mo></mrow> in is the group of output signals, M is a size of the window, f(·) is a function, sub_max is an index of a maximum signal of the group of output signals, and G is a positive real number. 9. The communication device as claimed in claim 1, wherein the time-to-frequency conversion operation comprises a Fast Fourier Transformation. 10. The communication device as claimed in claim 1, wherein the maximum signal has a maximum amplitude satisfying the detection condition. 11. A method for processing bandwidth estimation, comprising: receiving a first plurality of time-domain signals using a receiving circuit; converting the first plurality of time-domain signals into a first plurality of frequency-domain signals using a computing circuit according to a time-frequency conversion operation; performing an absolute value operation on the first plurality of frequency domain signals respectively using a magnitude circuit to generate the first plurality of output signals; and A selection circuit is used to select a maximum signal satisfying a detection condition from the first plurality of output signals. 12. The method according to claim 11, further comprising the following steps: using a bandwidth estimation circuit to estimate a bandwidth based on the maximum signal and a minimum output signal of the first plurality of output signals; and According to the bandwidth, a receiving circuit is used to calculate a symbol rate. 13. The communication device according to claim 11, further comprising: A frequency location of the maximum signal is determined using an interference estimation circuit. 14. The method according to claim 11, wherein when the first plurality of output signals does not include the maximum signal satisfying the detection condition, further comprising the following steps: using the receiving circuit to receive a second plurality of time-domain signals; converting the second plurality of time-domain signals into a second plurality of frequency-domain signals using the conversion circuit in accordance with the time-frequency conversion operation; performing the absolute value operation on the second plurality of frequency domain signals respectively using the magnitude circuit to generate a second plurality of output signals; and Using the selection circuit to correspondingly add the first plurality of output signals and the second plurality of output signals to generate a plurality of auxiliary signals, and select the maximum signal from the plurality of auxiliary signals and determine whether the maximum signal is meet the test conditions. 15. The method of claim 11, further comprising the steps of: According to a sliding window method, the selection circuit is used to sequentially select the maximum signal from a plurality of output signals of the first plurality of output signals with a window, and check whether the maximum signal satisfies the detection condition. 16. The method according to claim 15, wherein one group of output signals in the multiple groups of output signals satisfies the detection condition according to the following equation: <mrow><mi>f</mi><mrow><mo>(</mo><msubsup><mrow><mo>{</mo><msub><mi>Z</mi><mi>k</mi></msub><mo>}</mo></mrow><mrow><mi>k</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>&amp;NotEqual;</mo><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow><mi>M</mi></msubsup><mo>)</mo></mrow><mo>+</mo><msub><mi>Z</mi><mrow><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>&gt;</mo><mi>G</mi><mo>*</mo><msub><mi>Z</mi><mrow><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>;</mo></mrow> in is the group of output signals, M is a size of the window, f(·) is a function, sub_max is an index of a maximum signal of the group of output signals, and G is a positive real number. 17. The method of claim 16, wherein the function is the following equation: <mrow><mi>f</mi><mrow><mo>(</mo><msubsup><mrow><mo>{</mo><msub><mi>Z</mi><mi>k</mi></msub><mo>}</mo></mrow><mrow><mi>k</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>&amp;NotEqual;</mo><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow><mi>M</mi></msubsup><mo>)</mo></mrow><mo>=</mo><msubsup><mi>&amp;Sigma;</mi><mrow><mi>k</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>&amp;NotEqual;</mo><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow><mi>M</mi></msubsup><msub><mi>Z</mi><mi>k</mi></msub><mo>.</mo></mrow> 18. The method according to claim 15, wherein one group of output signals in the multiple groups of output signals satisfies the detection condition according to the following equation: <mrow><mi>f</mi><mrow><mo>(</mo><msubsup><mrow><mo>{</mo><msub><mi>Z</mi><mi>k</mi></msub><mo>}</mo></mrow><mrow><mi>k</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>&amp;NotEqual;</mo><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow><mi>M</mi></msubsup><mo>)</mo></mrow><mo>+</mo><msub><mi>Z</mi><mrow><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>&lt;</mo><mi>G</mi><mo>*</mo><msub><mi>Z</mi><mrow><mi>s</mi><mi>u</mi><mi>b</mi><mo>_</mo><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub><mo>;</mo></mrow> in is the group of output signals, M is a size of the window, f(·) is a function, sub_max is an index of a maximum signal of the group of output signals, and G is a positive real number. 19. The method of claim 11, wherein the time-to-frequency conversion operation comprises a fast Fourier transform. 20. The method of claim 11, wherein the maximum signal has a maximum amplitude satisfying the detection condition.