CN112332888B

CN112332888B - Frequency band selection method and terminal station

Info

Publication number: CN112332888B
Application number: CN202011086071.XA
Authority: CN
Inventors: 吕宜宣; 徐德超; 张国宾; 郭佳; 田甲申
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-04-10
Filing date: 2017-04-10
Publication date: 2021-10-26
Anticipated expiration: 2037-04-10
Also published as: CN108696296A; CN112332888A; CN108696296B

Abstract

The application provides a frequency band selection method and a terminal station, wherein the method comprises the following steps: acquiring a first sequence sent by a first terminal station, wherein the first sequence comprises a first preamble sequence which is a preamble sequence corresponding to a frequency band of a signal sent at the current moment in a PLC network; matching the first preamble sequence with each pre-stored preamble sequence in a pre-stored preamble sequence set to determine a target preamble sequence, wherein the pre-stored preamble sequence is a preamble sequence corresponding to a frequency band supported by a PLC network, and the target preamble sequence is a pre-stored preamble sequence required to be selected; and determining the frequency band corresponding to the target preamble sequence as the frequency band to be selected. In the embodiment of the invention, the second terminal station determines the frequency band to be selected by acquiring the lead code sequence sent by the first terminal station, so that the pilot frequency networking can be realized, the efficiency of selecting and switching the frequency band between the terminal stations in the PLC network is improved, and the time for the terminal stations to access the network is reduced.

Description

Frequency band selection method and terminal station

Technical Field

The present application relates to the field of communications, and in particular, to a method for selecting a frequency band and a terminal station.

Background

In a Power Line Communication (PLC) network, each network can communicate with each other through a Power Line, so as to realize mutual coordination of different networks, ensure independent operation of each network, and avoid conflict with other networks. Because the networking environment of the power line is complex, loads are opened or closed at variable time between the concentrator and each terminal station, and impedance, signal attenuation, interference and the like introduced by the loads are different, so that normal communication cannot be performed between partial terminal stations in the network.

Disclosure of Invention

The frequency band selection method and the terminal station can realize pilot frequency networking of a PLC network, improve the efficiency of frequency band selection and switching among the terminal stations in the PLC network, and reduce the network access time of the terminal stations.

On one hand, a method for selecting a frequency band is provided, which includes acquiring a first sequence sent by a first terminal station, where the first sequence includes a first preamble sequence, and the first preamble sequence is a preamble sequence corresponding to a frequency band for sending a signal at the current time in a power line communication PLC network; matching the first preamble sequence with each pre-stored preamble sequence in a pre-stored preamble sequence set to determine a target preamble sequence, wherein the pre-stored preamble sequence is a preamble sequence corresponding to a frequency band supported by a PLC network, and the target preamble sequence is the pre-stored preamble sequence required to be selected; and determining the frequency band corresponding to the target preamble sequence as the frequency band to be selected.

In an embodiment of the invention, the second terminal station obtains a first sequence comprising a first preamble sequence transmitted by the first terminal station, the first preamble sequence is a preamble sequence corresponding to a frequency band for transmitting signals in the PLC network at the current time, the second terminal station matches the first preamble sequence with a preamble sequence corresponding to a frequency band supported by the PLC network, determines a target preamble sequence, determines a frequency band corresponding to the target preamble sequence as a frequency band to be selected, the frequency band to be selected may be different from the frequency band being used between other terminal stations in the PLC network, and, therefore, the pilot frequency networking can be realized, and when the frequency band between the terminal stations is replaced, the frequency band supported by the PLC network does not need to be detected one by one, so that the efficiency of frequency band selection and switching between the terminal stations in the PLC network is improved, and the time for the terminal stations to access the network is reduced.

With reference to the first aspect, in a first implementation manner of the first aspect, before the matching the first preamble sequence with each pre-stored preamble sequence in a set of pre-stored preamble sequences, the method further includes: determining different cyclic shift lengths according to the number of frequency bands supported by the PLC network; and according to the different cyclic shift lengths, performing different cyclic shifts on the phase of a first pre-stored preamble sequence, and determining other pre-stored preamble sequences in the pre-stored preamble sequence set except the first pre-stored preamble sequence, wherein the first pre-stored preamble sequence is a preamble sequence pre-stored in the pre-stored preamble sequence set.

In the embodiment of the invention, the phases of different preamble sequences are obtained through cyclic shift, so that the preamble sequences corresponding to different frequency bands are obtained, and a terminal station does not need to store a plurality of preamble sequences, thereby saving the storage space of the terminal station, saving the signaling overhead and being beneficial to avoiding resource waste.

With reference to the first aspect, the first implementation manner of the first aspect, and in a second implementation manner of the first aspect, the matching the first preamble sequence with each pre-stored preamble sequence in a set of pre-stored preamble sequences to determine a target preamble sequence includes: performing correlation operation on the first preamble sequence and each pre-stored preamble sequence in the pre-stored preamble sequence set to determine a peak-to-average ratio; and determining the target preamble sequence in the pre-stored preamble sequences according to the peak-to-average ratio.

With reference to the first aspect, the first and second implementation manners of the first aspect, and in a third implementation manner of the first aspect, the determining a target preamble sequence in the pre-stored preamble sequences according to the peak-to-average ratio includes: and when the peak-to-average ratio is greater than a first preset threshold value, determining the pre-stored preamble sequence with the peak-to-average ratio greater than the first preset threshold value as a target preamble sequence.

With reference to the first aspect, the first to third implementation manners of the first aspect, and in a fourth implementation manner of the first aspect, when there are more than one pre-stored preamble sequences whose peak-to-average ratios are greater than the first preset threshold, it is determined that the pre-stored preamble sequence with the largest peak-to-average ratio in the pre-stored preamble sequences whose peak-to-average ratios are greater than the first preset threshold is the target preamble sequence.

With reference to the first aspect, the first to fourth implementation manners of the first aspect, and in a fifth implementation manner of the first aspect, the determining a target preamble sequence in the pre-stored preamble sequences according to the peak-to-average ratio includes: determining the peak-to-average ratio with the largest ratio in the peak-to-average ratios; and determining the pre-stored preamble sequence corresponding to the peak-to-average ratio with the largest ratio in the peak-to-average ratios as the target preamble sequence.

With reference to the first aspect, the first to fifth implementation manners of the first aspect, and in a sixth implementation manner of the first aspect, before the matching the first preamble sequence with each pre-stored preamble sequence in a set of pre-stored preamble sequences, the method further includes: determining whether the communication success rate with the first terminal station is smaller than a second preset threshold value; when the communication success rate is less than the second preset threshold, matching the first preamble sequence with each pre-stored preamble sequence in the set of pre-stored preamble sequences.

With reference to the first aspect, the first to sixth implementation manners of the first aspect, in a seventh implementation manner of the first aspect, before the matching the first preamble sequence with each pre-stored preamble sequence in a set of pre-stored preamble sequences, the method further includes: determining a frame header of the first preamble sequence in the first sequence.

In a second aspect, a method for selecting a frequency band is provided, including: determining an initial reference phase, wherein the initial reference phase is the phase of a subcarrier corresponding to any one of frequency bands supported by a power line communication PLC network; generating a first preamble sequence according to the initial reference phase, wherein the first preamble sequence is a preamble sequence corresponding to a frequency band of a signal transmitted at the current time in the PLC network; transmitting a first sequence to a second terminal station, the first sequence comprising the first preamble sequence.

In the embodiment of the invention, the terminal station obtains the phases of different preamble sequences through cyclic shift so as to obtain the first preamble sequences corresponding to different frequency bands, so that the terminal station does not need to store a plurality of first preamble sequences, thereby saving the storage space of the terminal station, saving the signaling overhead and being beneficial to avoiding resource waste.

With reference to the second aspect, in a first implementation manner of the second aspect, the generating a first preamble sequence according to the initial reference phase includes: determining a first reference phase according to the initial reference phase, wherein the first reference phase is the phase of a subcarrier corresponding to the frequency band of the signal transmitted at the current moment in the PLC network; generating the first preamble sequence according to the first reference phase.

With reference to the second aspect, the first implementation manner of the second aspect, and in a second implementation manner of the second aspect, the determining a first reference phase according to the initial reference phase includes: determining the length of cyclic shift according to the frequency band number between the frequency band of the signal sent at the current moment in the PLC network and the frequency band corresponding to the initial reference phase; and according to the length of the cyclic shift, performing cyclic shift on the initial reference phase to determine the first reference phase.

In a third aspect, there is provided an end station comprising one or more modules for performing the method of the first aspect.

In a fourth aspect, there is provided an end station comprising one or more modules for performing the method of the second aspect.

In a fifth aspect, there is provided an end station comprising one or more modules for performing the method of the first aspect.

In a sixth aspect, there is provided an end station comprising one or more modules for performing the method of the second aspect.

In a seventh aspect, a computer-readable medium is provided, which is configured to store program code executable by a second terminal station, where the program code includes instructions for performing the method of the first aspect and the implementation manners of the first aspect.

In an eighth aspect, a computer-readable medium is provided for storing program code executable by a first terminal station, the program code comprising instructions for performing the method of the second aspect described above and its implementations.

Drawings

Fig. 1 is a schematic diagram of a PLC network in the prior art for performing frequency band switching.

Fig. 2 is a schematic diagram of frequency band selection performed by a newly-accessed terminal station in a PLC network in the prior art.

Fig. 3 is a schematic flow chart of a method of frequency band selection according to an embodiment of the present invention.

Fig. 4 is another schematic flow chart of a method of frequency band selection according to an embodiment of the present invention.

Fig. 5 is a further schematic flow chart of a method of frequency band selection according to an embodiment of the present invention.

Fig. 6 is a schematic block diagram of an end station according to an embodiment of the present invention.

Fig. 7 is another schematic block diagram of an end station according to an embodiment of the present invention.

Fig. 8 is another schematic block diagram of an end station according to an embodiment of the present invention.

Fig. 9 is yet another schematic block diagram of an end station according to an embodiment of the present invention.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

At present, in the field of Power Line Communication (PLC), the Power Line Communication network basically adopts a single frequency band networking form, and when the single frequency band networking is adopted, the problems as described in fig. 1 and fig. 2 are often encountered.

Fig. 1 is a schematic diagram illustrating frequency band switching of a PLC network, as shown in fig. 1, during operation of the PLC network, at a certain time, due to signal fading or noise, and other factorsInterference of interfering signals, resulting in the frequency band F used between terminal stations C and F₁The frequency bands used between the station C and the station F need to be switched due to unavailability, which causes that the station F and the Central Coordinator (CCO) a station cannot perform normal communication, however, since a single networking manner is used in the existing PLC network and it is not known to which frequency band the frequency bands of the station C and the station F need to be changed, the frequency bands between all the stations in the PLC network need to be changed in a normal case. When frequency bands are replaced between all the terminal stations, it is necessary to find a frequency band suitable for all the terminal stations, for example, a frequency band f currently used in the PLC network₁Is changed to f₃In this case, the terminal station C and the terminal station F may communicate normally, but normal communication may not be performed between the terminal station a and the terminal station B, and the frequency bands may need to be switched again until the frequency bands suitable for all the stations are found.

Fig. 2 is a schematic diagram illustrating frequency band selection performed by a newly-accessed terminal station in a PLC network, and as shown in fig. 2, since the newly-accessed terminal station N does not know a frequency band used by an upstream terminal station at the present time, the terminal station N needs to perform one-by-one investigation on all frequency bands supported by the PLC network until finding a frequency band used by the upstream station, however, when the number of frequency bands supported by the PLC network is large, the access time of the newly-accessed terminal station is relatively long at this time.

In the prior art, because the PLC network mostly uses a single frequency band networking mode, when the frequency band of an individual terminal station cannot be used, the whole network cannot use the frequency band, and the frequency bands of all terminal stations need to be replaced.

Based on the prior art shown in fig. 1 and fig. 2 and the problems in the prior art, an embodiment of the present invention provides a method for selecting a frequency band, where when two terminal stations in a PLC network are not in communication or a new terminal station needs to join in the PLC network, an upstream terminal station of the two terminal stations that are not in communication or an upstream terminal station of the terminal station that newly joins in the PLC network may send a preamble sequence to a downstream terminal station, and the downstream terminal station determines, by matching the received preamble sequence with a preamble sequence corresponding to a frequency band supported by the PLC network, a preamble sequence that matches the preamble sequence sent by the upstream terminal station, so as to determine a frequency band that needs to be selected or switched according to the matched preamble sequence, where the selected frequency band may be different from a frequency band corresponding to the preamble sequence sent by the upstream terminal station, but also can ensure the normal communication between the terminal stations in the PLC network, thereby realizing the pilot frequency networking of the PLC network, improving the selection and switching speed of the frequency bands between the terminal stations in the PLC network and reducing the network access time of the terminal stations.

Fig. 3 is a schematic flow chart of a method 300 for selecting a frequency band according to an embodiment of the present invention, where the method 200 may be performed by any one of the end stations in the PLC network, for example, a downstream end station of two end stations that have poor communication or a newly-connected end station. As shown in fig. 3, the method 300 includes:

310, acquiring a first sequence sent by a first terminal station, where the first sequence includes a first preamble sequence, and the first preamble sequence is a preamble sequence corresponding to a frequency band of a signal sent at the current time in a power line communication PLC network;

320, matching the first preamble sequence with each pre-stored preamble sequence in a pre-stored preamble sequence set to determine a target preamble sequence, where the pre-stored preamble sequence is a preamble sequence corresponding to a frequency band supported by a PLC network, and the target preamble sequence is the pre-stored preamble sequence to be selected;

and 330, determining the frequency band corresponding to the target preamble sequence as the frequency band to be selected.

It should be understood that an upstream terminal station of two terminal stations in the PLC network, where communication is not smooth, may be used as a first terminal station, and a downstream terminal station may be used as a second terminal station, that is, the execution main body of the method 300, for example, the terminal station C and the terminal station F shown in fig. 1 cannot normally communicate, and at this time, the terminal station C may be used as the first terminal station, and the terminal station F may be used as the second terminal station; alternatively, a newly-accessed terminal station may be the second terminal station, and a terminal station upstream of the newly-accessed terminal station may be the first terminal station, for example, terminal station N shown in fig. 2 may be the newly-accessed terminal station, in which case, terminal station G may be the first terminal station and terminal station N may be the second terminal station, and method 300 may be executed with the second terminal station as the main execution body.

It should be understood that when communication is not smooth between the terminal stations and a frequency band used between the terminal stations needs to be switched, at this time, the switched frequency band may be the same as or different from a frequency band used by other terminal stations, because communication is not smooth between two terminal stations, an original frequency band cannot be used between the two terminal stations, when the switched frequency band is determined, only the frequency band supported by the PLC network except the original frequency band needs to be selected and switched, as long as preamble sequences of other frequency bands are matched with preamble sequences corresponding to frequency bands being used by other terminal stations in the PLC network, the determined other frequency bands can be combined with the frequency bands being used by other terminal stations in the PLC network at the current time, so as to ensure normal communication between the terminal stations, and therefore, a function of inter-frequency networking can be achieved, or, in a short time after two terminal stations are in unsmooth communication, the original frequency band can enable the communication between the two terminal stations to be normal again, and at the moment, if the frequency band switching is started, the frequency band needing to be switched can be determined as the original frequency band; when a terminal station newly accesses the network, the frequency band to be selected at this time may be the same frequency band as the frequency band used by the upstream station at the current time, or may be a different frequency band, as long as the selected frequency band is combined with the frequency band currently used by the upstream station at the current time, normal communication between the terminal stations may be ensured, that is, all the frequency bands supported by the PLC network may be selected, and when a different frequency band is selected, inter-frequency networking may also be implemented.

Optionally, in some embodiments, the first preamble sequence is a preamble sequence corresponding to a frequency band for transmitting a signal at the current time, for example, the frequency band f shown in fig. 1₁A corresponding preamble sequence.

It should be understood that frequency bands in a PLC network may be identified by preamble sequences, different frequency bands using different preamble sequences, and therefore, in the embodiment of the invention, when the terminal stations can not normally communicate with each other, or the terminal stations are accessed to the network, since the downstream terminal station that cannot normally communicate or the newly-accessed terminal station is in an offline state, at this time, the downstream end station or the newly network-connected end station cannot receive the signal transmitted by the upstream end station, therefore, the frequency band of the downstream terminal station or the newly accessed terminal station cannot be directly switched, but the downstream or newly-networked terminal station may receive the preamble sequence transmitted by the upstream terminal station, therefore, the frequency band to be selected or switched by the downstream station can be determined through matching between the preamble sequence transmitted by the upstream terminal station and the preamble sequence supported in the PLC network.

Optionally, in some embodiments, only one of the preamble sequences corresponding to the frequency bands supported by the PLC network may be stored in the set of pre-stored preamble sequences in advance, for example, only the frequency band f is stored in the set of pre-stored preamble sequences₁And the corresponding preamble sequences, namely, the preamble sequences corresponding to other frequency bands supported by the PLC network, can be obtained by performing cyclic shift on the preamble sequences pre-stored in the pre-stored preamble sequence set, so that the terminal station is facilitated to save signaling overhead, and resource waste is avoided.

Specifically, after a preamble sequence pre-stored in the pre-stored preamble sequence set, that is, a first pre-stored preamble sequence, is obtained, different cyclic shift lengths are determined according to the number of frequency bands supported by the PLC network, and according to the different cyclic shift lengths, cyclic shift is performed on a phase of the first pre-stored preamble sequence to obtain phases corresponding to different pre-stored preamble sequences, so that other pre-stored preamble sequences except the first pre-stored preamble sequence in the preamble sequence corresponding to the frequency band supported by the PLC network can be obtained.

For example, the pre-stored preamble sequence in the set of pre-stored preamble sequences is the frequency band f₁Corresponding lead code sequence, the frequency band supported by the PLC network comprises f₁、f₂、f₃、f₄、f₅Obtaining the frequency band f when necessary₂Corresponding to the preamble sequence, the frequency band f can be adjusted₁Performing a cyclic shift on the phase of the corresponding preamble sequence to obtain the frequency band f₂Corresponding lead code sequence, and obtaining the frequency band f when needed₃Corresponding to the preamble sequence, the frequency band f can be adjusted₁Performing two times of cyclic shift on the phase of the corresponding preamble sequence to obtain a frequency band f₃A corresponding preamble sequence.

Optionally, in some embodiments, when performing cyclic shift on a phase of a first pre-stored preamble sequence to obtain another pre-stored preamble sequence, first a phase of a subcarrier of a frequency band corresponding to the first pre-stored preamble sequence needs to be determined, where the phase is used as an initial phase, when a pre-stored preamble sequence of another frequency band needs to be obtained, different cyclic shifts are actually performed on the initial phase to obtain a phase of a subcarrier of a desired frequency band, the phase after the cyclic shift is used as a target phase, and according to the target phase, the pre-stored preamble sequence corresponding to the target phase can be determined, so as to determine another pre-stored preamble sequence in the set of pre-stored preamble sequences except the first pre-stored preamble sequence.

It should be understood that any pre-stored preamble sequence in the set of pre-stored preamble sequences may be obtained by performing different phase conversions according to the same source preamble sequence, and the source preamble sequence may be any one of the preamble sequences corresponding to the frequency bands supported by the PLC network, for example, the first pre-stored preamble sequence used in the embodiment of the present invention may also be another preamble sequence, which is not limited in this invention.

Optionally, in some embodiments, the first terminal station may also store only one of preamble sequences corresponding to frequency bands supported by the PLC network, and when a frequency band in which the PLC network sends a signal at the current time is different from a frequency band corresponding to a preamble sequence stored in the first terminal device, the preamble sequence may be obtained by performing different cyclic shifts on phases of the preamble sequences stored in the first terminal station.

Optionally, in some embodiments, the preamble sequence pre-stored by the first terminal station may not be the preamble sequence corresponding to the frequency band supported by the PLC network, and may be any one of the preamble sequences, as long as the preamble sequence corresponding to the frequency band in which the signal is transmitted, that is, the first preamble sequence, may be obtained by performing phase according to the preamble sequence pre-stored by the first terminal station.

Specifically, the first terminal station determines a phase of a preamble sequence corresponding to any one of frequency bands supported by the PLC network as an initial reference phase, and when the first preamble sequence needs to be determined, the first reference phase may be obtained by performing cyclic shift on the initial reference phase, so as to obtain the first preamble sequence through the first reference phase.

Optionally, in some embodiments, a specific process of obtaining the first reference phase through the initial reference phase may be: determining the length of cyclic shift required according to the frequency band number between the frequency band of the signal sent by the PLC network at the current moment and the frequency band of the lead code sequence corresponding to the initial reference phase, and performing cyclic shift on the initial reference phase according to the determined length of the cyclic shift to obtain a first reference phase.

In the embodiment of the invention, the phases of different preamble sequences are obtained through cyclic shift, so that the preamble sequences corresponding to different frequency bands are obtained, and a terminal station does not need to store a plurality of preamble sequences, thereby saving the storage space of the terminal station, saving the signaling overhead and avoiding the resource waste.

Optionally, in some embodiments, when the first preamble sequence is matched with a pre-stored preamble sequence and a target preamble sequence is determined, correlation operation may be performed on the first preamble sequence and a preamble sequence corresponding to a frequency band supported by a PLC network, where the preamble sequence corresponding to the frequency band supported by the PLC network is a pre-stored preamble sequence obtained by performing different cyclic shifts on a phase of the first pre-stored preamble sequence in a pre-stored preamble sequence set, after the correlation operation, a plurality of peak-to-average ratios are determined, and when the peak-to-average ratio is greater than a first preset threshold, the pre-stored preamble sequence whose peak-to-average ratio is greater than the first preset threshold is determined as the target preamble sequence.

It should be understood that there may be only one or more pre-stored preamble sequences with a peak-to-average ratio greater than the first preset threshold, and in the embodiments of the present invention, all the pre-stored preamble sequences with a peak-to-average ratio greater than the first preset threshold may be used as target preamble sequences, one pre-stored preamble sequence may be randomly selected from the pre-stored preamble sequences with a peak-to-average ratio greater than the first preset threshold as a target preamble sequence, or a target preamble sequence may be selected from a plurality of pre-stored preamble sequences with a peak-to-average ratio greater than the first preset threshold by a certain rule, where the certain rule may be that the pre-stored preamble sequence with a maximum peak-to-average ratio is selected from the plurality of pre-stored preamble sequences with a peak-to-average ratio greater than the first preset threshold as a target preamble sequence.

Optionally, in some embodiments, when the first preamble sequence is matched with the pre-stored preamble sequence and the target preamble sequence is determined, correlation operation may be performed on the first preamble sequence and the preamble sequence corresponding to the frequency band supported by the PLC network, and when the peak-to-average ratio is obtained, the pre-stored preamble with the largest peak-to-average ratio is determined as the target preamble.

It should be understood that the present invention is only illustrated by selecting the pre-stored preamble sequence with the largest peak-to-average ratio as the target preamble sequence, but the embodiments of the present invention are not limited thereto.

Optionally, in some embodiments, before the first preamble sequence is matched with the pre-stored preamble sequence, a communication success rate between the second terminal station and the first terminal station needs to be determined, and when the communication success rate is lower than a second preset threshold, the first preamble sequence is matched with each pre-stored preamble sequence in the pre-stored preamble sequence set; when the communication success rate is higher than the second preset threshold, it is indicated that the frequency band used between the first terminal station and the second terminal station can also maintain normal communication at this time, and frequency band switching or selection is not required, so that the first preamble sequence does not need to be matched with each pre-stored preamble sequence in the pre-stored preamble sequence set.

Optionally, the second preset threshold may be an empirical value, and is obtained by counting the success rate of the PLC network communication at ordinary times.

Optionally, in some embodiments, before matching the first preamble sequence with the pre-stored preamble sequence, a frame header of the first preamble sequence in the first sequence needs to be determined, because the first sequence acquired by the second terminal station is a long sequence including the first preamble sequence, the first sequence may further include a preamble sequence of a noise signal or other interference signal, and the second terminal station needs to find the frame header of the first preamble sequence to match the first preamble sequence with the pre-stored preamble sequence.

Specifically, since the length of the preamble sequence is constant, the first sequence may be divided into a plurality of subsequences according to the length of one preamble sequence, when determining the frame header of the first preamble sequence in the first sequence, first performing correlation operation on the first subsequence and the second subsequence in the divided subsequences to obtain a correlation peak, determining whether the correlation peak is greater than a third preset threshold value, when the correlation peak is greater than the third predetermined threshold, the start position of the first sub-sequence is the start position of the first preamble included in the first sequence, and when the correlation peak is smaller than a third preset threshold, continuing to perform correlation operation on the second subsequence and the third subsequence, and comparing the correlation peak obtained by the operation with the third preset threshold again until the frame header of the first preamble sequence in the first sequence is determined.

It will be appreciated that there may be a plurality of first preamble sequences in the first sequence, and that any one of the first sequences may be matched to a pre-stored preamble sequence when matching the first preamble sequence to a pre-stored preamble sequence.

It should also be understood that, when determining the frame header of the first preamble sequence in the first sequence, the frame header of the determined first preamble sequence may be the starting position of the first preamble sequence in the first sequence, or may be the starting position of any one of the first preamble sequences, which is not limited in this embodiment of the present invention.

In the embodiment of the invention, the second terminal station determines the frequency band to be selected or switched by matching the received lead code sequence sent by the first terminal station with the lead code sequence corresponding to the frequency band supported by the PLC network, thereby realizing the function of different-frequency networking of the PLC network, improving the speed of selecting and switching the frequency band among the terminal stations in the PLC network and reducing the time for the terminal stations to access the network.

Fig. 4 is a schematic flowchart of a method 400 for selecting a frequency band according to an embodiment of the present invention, where the method 400 is executed by a first end station, for example, by an upstream station in two stations that cannot normally communicate in a PLC network, or by an upstream end station in a newly-connected end station, and as shown in fig. 4, the method 400 includes:

an initial reference phase is determined 410.

Optionally, in some embodiments, the initial reference phase is a phase of a subcarrier corresponding to any one of frequency bands supported by the PLC network, and the initial reference phase corresponds to a preamble sequence in a time domain.

It should be understood that the preamble sequence corresponding to the initial reference phase may be a preamble sequence corresponding to any one of the frequency bands supported by the PLC network, or may also be a preamble sequence corresponding to other frequency bands.

The length of the cyclic shift required is determined 420.

Optionally, in some embodiments, the length of the cyclic shift is determined by the number of frequency bands between the frequency band of the current transmission signal and the frequency band corresponding to the initial reference phase.

For example, the preamble sequence pre-stored by the first terminal station is the frequency band f₁Corresponding preamble sequence, the frequency band of the signal sent at the current time is frequency band f₃Therefore, the length of the cyclic shift is 2.

430, a first reference phase is determined based on the length of the cyclic shift.

Optionally, in some embodiments, the first reference phase is a phase of a subcarrier corresponding to a frequency band of a signal transmitted at the current time.

Optionally, in some embodiments, the initial reference phase is cyclically shifted according to the determined length of the cyclic shift, so as to obtain the first reference phase.

For example, the first terminal stationThe pre-stored preamble sequence is a frequency band f₁Corresponding preamble sequence, where the initial reference phase is the frequency band f₁The phase of the corresponding subcarrier and the frequency band of the signal transmitted at the current moment are the frequency band f₃Therefore, it is necessary to obtain the frequency band f₃The corresponding preamble sequence can perform two cyclic shifts on the initial reference phase to obtain the frequency band f₃Reference phase of corresponding sub-carrier, the frequency band f₃The reference phase of the corresponding subcarrier is the first reference phase.

A first preamble sequence is determined 440 based on the first reference phase.

Optionally, in some embodiments, an Inverse Fast Fourier Transform (IFFT) is performed on the first reference phase to determine the first preamble sequence.

In the embodiment of the present invention, when the first terminal station sends the preamble sequence to the second terminal station, the sent preamble sequence may not be directly stored in the first terminal station, and the preamble sequence to be sent to the second terminal station is obtained by performing cyclic shift through the phase of the preamble sequence stored in the first terminal station, so that the storage space of the first terminal station can be saved, the signaling overhead of the first terminal station is saved, and the resource waste is avoided.

Fig. 5 is a schematic flowchart of a method 500 for selecting a frequency band according to an embodiment of the present invention, where the method 500 is executed by a second terminal station, for example, the method 500 may be executed by a downstream terminal station of two terminal stations that cannot normally communicate, or by a newly-connected terminal station, as shown in fig. 5, where the method 500 includes:

and 510, receiving data information sent by the first terminal station.

It is determined 520 whether the communication success rate with the first terminal station is greater than a second preset threshold.

Optionally, in some embodiments, the second terminal station needs to determine, in real time, a communication success rate of the second terminal station with the first terminal station, and when the communication success rate is lower than a second preset threshold, match the first preamble sequence with each pre-stored preamble sequence in the set of pre-stored preamble sequences; when the communication success rate is higher than the second preset threshold, it is indicated that the frequency band used between the first terminal station and the second terminal station can also maintain normal communication at this time, and frequency band switching is not required, so that the first preamble sequence does not need to be matched with each pre-stored preamble sequence in the pre-stored preamble sequence set.

And 530, when the communication success rate is smaller than a second preset threshold, determining a frame header of a first preamble sequence in a first sequence sent by the first terminal station.

It should be understood that the first sequence transmitted by the first terminal station and received by the second terminal station is a long sequence including the first preamble sequence, and the first sequence may also include a preamble sequence of a noise signal or other interference signal, and the second terminal station needs to find the frame header of the first preamble to match the first preamble sequence with the pre-stored preamble sequence.

Optionally, in some embodiments, when the frame header of the first preamble in the first sequence is determined, because the length of the preamble is fixed, the first sequence may be divided into a plurality of subsequences according to the length of one preamble sequence, when the frame header of the first preamble sequence in the first sequence is determined, first, correlation operation may be performed on the first sequence and the second subsequence in the divided subsequences to obtain a correlation peak, it is determined whether the correlation peak is greater than a third preset threshold, when the correlation peak is greater than the third preset threshold, the start position of the first subsequence is the start position of the first preamble included in the first sequence, when the correlation peak is less than the third preset threshold, correlation operation is continued to be performed on the second subsequence and the third subsequence, and the size of the correlation peak obtained by the operation is compared with the third preset threshold again, until a frame header of a first preamble sequence in the first sequence is determined.

It should be understood that, when determining the first preamble sequence in the first sequence, the frame header of the determined first preamble sequence may be the starting position of the first preamble sequence in the first sequence, or may be the starting position of any one of the first preamble sequences, which is not limited in this embodiment of the present invention.

Optionally, in some embodiments, when correlation peaks obtained by performing correlation operation between every two of the subsequences are smaller than a second preset threshold, the first sequence including the first preamble sequence sent by the first terminal station needs to be received again, and the above determination is performed again.

And 540, after the frame header of the first preamble sequence in the first sequence is determined, matching the first preamble sequence with a pre-stored preamble sequence to determine the peak-to-average ratio.

Optionally, in some embodiments, after the first preamble sequence is matched with the pre-stored preamble sequence, correlation operation may be performed on the first preamble sequence and a preamble sequence corresponding to a frequency band supported by the PLC network, where the preamble sequence corresponding to the frequency band supported by the PLC network is a pre-stored preamble sequence obtained by different cyclic shifts for the first pre-stored preamble sequence in the pre-stored preamble sequence set, and after the correlation operation is performed, a plurality of peak-to-average ratios are determined.

Optionally, in some embodiments, when the first preamble sequence is matched with the pre-stored preamble sequence, the first preamble sequence and the pre-stored preamble sequence may be matched one by a time division multiplexing method until the preamble sequences corresponding to all frequency bands supported by the PLC are matched with the first preamble sequence.

And 550, determining the pre-stored preamble sequence corresponding to the maximum value in the peak-to-average ratio as a target preamble sequence.

It should be understood that, in the two sequences subjected to the correlation operation, the larger the peak-to-average ratio, the higher the similarity of the two sequences, and therefore, the pre-stored preamble sequence with the largest peak-to-average ratio has the highest similarity with the first preamble sequence, so that the pre-stored preamble sequence with the largest peak-to-average ratio is determined as the target preamble sequence.

And 560, taking the frequency band corresponding to the target preamble sequence as the frequency band required to be selected and switched.

In the embodiment of the invention, the second terminal station determines the target preamble sequence matched with the preamble sequence sent by the first station by matching the received preamble sequence sent by the first terminal station with the preamble sequence supported by the PLC network, and determines the frequency band to be selected according to the determined target preamble sequence, so that the frequency band switching or the selected frequency band among the stations in the PLC network is improved, and the network access time of the terminal station accessing the network is reduced.

While the method embodiments of the present invention are described in detail above with reference to fig. 3 to 5, the terminal station embodiments of the present invention will be described in detail below with reference to fig. 6 to 9, it should be understood that the terminal station embodiments correspond to the method embodiments, and similar descriptions may refer to the method embodiments.

Fig. 6 is a schematic block diagram of an end station 600 according to an embodiment of the present invention, and as shown in fig. 6, the end station 600 includes:

an obtaining module 610, configured to obtain a first sequence sent by a first terminal station, where the first sequence includes a first preamble sequence, and the first preamble sequence is a preamble sequence corresponding to a frequency band of a signal sent at a current time in a power line communication PLC network;

a determining module 620, configured to match the first preamble sequence with each pre-stored preamble sequence in a set of pre-stored preamble sequences, and determine a target preamble sequence, where the pre-stored preamble sequence is a preamble sequence corresponding to a frequency band supported by a PLC network, and the target preamble sequence is the pre-stored preamble sequence that needs to be selected;

the determining module 620 is further configured to determine a frequency band corresponding to the target preamble sequence as a frequency band to be selected.

It should be understood that the terminal station 600 may be any one of the terminal stations in the PLC network, for example, a downstream terminal station of two terminal stations that are in poor communication, or a newly-connected terminal station.

It should be further understood that an upstream terminal station of two terminal stations in the PLC network, which are not in communication with each other, may be used as a first terminal station, and a downstream terminal station may be used as a second terminal station, which is the terminal station 600, for example, the terminal station C and the terminal station F shown in fig. 1 may not normally communicate, and at this time, the terminal station C may be used as the first terminal station, and the terminal station F may be used as the terminal station 600; alternatively, a newly-accessed terminal station may be the terminal station 600, and a terminal station upstream of the newly-accessed terminal station may be the first terminal station, for example, the terminal station N shown in fig. 2 may be the newly-accessed terminal station, in which case, the terminal station G may be the first terminal station and the terminal station N may be the terminal station 600.

In an embodiment of the invention, the terminal station 600 obtains a first sequence comprising a first preamble sequence transmitted by a first terminal station, the first preamble sequence is a preamble sequence corresponding to a frequency band for transmitting a signal in the PLC network at the current time, the terminal station 600 matches the first preamble sequence with a preamble sequence corresponding to a frequency band supported by the PLC network, determines a target preamble sequence, determines a frequency band corresponding to the target preamble sequence as a frequency band to be selected, the frequency band to be selected may be different from the frequency band being used between other terminal stations in the PLC network, and, therefore, the pilot frequency networking can be realized, and when the frequency band between the terminal stations is replaced, the frequency band supported by the PLC network does not need to be detected one by one, so that the selection and switching speed of the frequency band between the terminal stations in the PLC network is improved, and the network access time of the terminal stations is reduced.

It should be understood that frequency bands in a PLC network may be identified by preamble sequences, different frequency bands using different preamble sequences, and therefore, in the embodiment of the invention, when the terminal stations can not normally communicate with each other, or the terminal stations are accessed to the network, since the downstream terminal station that cannot normally communicate or the newly-accessed terminal station is in an offline state, at this time, the downstream end station or the newly network-connected end station cannot receive the signal transmitted by the upstream end station, therefore, the frequency band of the downstream terminal station or the newly accessed terminal station cannot be directly switched, but the downstream or newly-networked terminal station may receive the preamble sequence transmitted by the upstream terminal station, therefore, the frequency band to be selected or switched by the downstream station can be determined by matching the preamble sequence transmitted by the upstream terminal station with the preamble sequence supported in the PLC network.

Optionally, in some embodiments, the determining module 620 is further configured to determine different cyclic shift lengths according to the number of frequency bands supported by the PLC network.

Optionally, in some embodiments, the determining module 620 is further configured to perform different cyclic shifts on the phase of the first pre-stored preamble sequence according to the different cyclic shift lengths, and determine other pre-stored preamble sequences in the set of pre-stored preamble sequences except for the first pre-stored preamble sequence, where the first pre-stored preamble sequence is a pre-stored preamble sequence in the set of pre-stored preamble sequences.

Optionally, in some embodiments, only one of the preamble sequences corresponding to the frequency bands supported by the PLC network may be stored in the set of prestored preamble sequences.

For example, only frequency band f is stored in the set of pre-stored preamble sequences₁And the corresponding preamble sequences, namely, the preamble sequences corresponding to other frequency bands supported by the PLC network, can be obtained by performing cyclic shift on the preamble sequences pre-stored in the pre-stored preamble sequence set, so that the terminal station is facilitated to save signaling overhead, and resource waste is avoided.

Optionally, in some embodiments, the determining module 620 is specifically configured to perform correlation operation on the first preamble sequence and each pre-stored preamble sequence in the set of pre-stored preamble sequences, and determine a peak-to-average ratio; and determining the target preamble sequence in the pre-stored preamble sequences according to the peak-to-average ratio.

Optionally, in some embodiments, the determining module 620 is specifically configured to determine, when the peak-to-average ratio is greater than a first preset threshold, a pre-stored preamble sequence with the peak-to-average ratio greater than the first preset threshold as the target preamble sequence.

Optionally, in some embodiments, when there are more than one pre-stored preamble sequences with peak-to-average ratios greater than a first preset threshold, the pre-stored preamble sequence with the largest peak-to-average ratio in the pre-stored preamble sequences with peak-to-average ratios greater than the first preset threshold is determined as the target preamble sequence.

Optionally, in some embodiments, the determining module 620 is specifically configured to determine a peak-to-average ratio with a largest ratio among the peak-to-average ratios; and determining the pre-stored preamble sequence corresponding to the peak-to-average ratio with the maximum ratio in the peak-to-average ratios as a target preamble sequence.

Optionally, in some embodiments, the determining module 620 is further configured to determine whether a communication success rate of the terminal station 600 with the first terminal station is less than a second preset threshold.

Optionally, in some embodiments, the terminal station 600 further includes a processing module 630, and the processing module 630 is configured to match the first preamble sequence with each pre-stored preamble sequence in the set of pre-stored preamble sequences when the communication success rate is smaller than the second preset threshold.

For example, when the communication success rate is lower than a second preset threshold, the processing module 630 further matches the first preamble sequence with each pre-stored preamble sequence in the set of pre-stored preamble sequences; when the communication success rate is higher than the second preset threshold, it indicates that the frequency band used between the first terminal station and the second terminal station can also maintain normal communication at this time, and there is no need to perform frequency band switching or selection, so that the processing module 630 is not required to match the first preamble sequence with each pre-stored preamble sequence in the pre-stored preamble sequence set.

Optionally, in some embodiments, the determining module 620 is further configured to determine a frame header of the first preamble sequence in the first sequence.

Optionally, in some embodiments, the first sequence acquired by the terminal station 600 is a long sequence including a first preamble sequence, the first sequence may further include a preamble sequence of a noise signal or other interference signal, and the terminal station 600 needs to find a frame header of the first preamble before the first preamble sequence can be matched with the pre-stored preamble sequence.

Specifically, since the length of the preamble sequence is constant, the determining module 620 may divide the first sequence into a plurality of subsequences according to the length of one preamble sequence, when determining the frame header of the first preamble sequence in the first sequence, first performing correlation operation on the first subsequence and the second subsequence in the divided subsequences to obtain a correlation peak, determining whether the correlation peak is greater than a third preset threshold value, when the correlation peak is greater than the third predetermined threshold, the start position of the first sub-sequence is the start position of the first preamble included in the first sequence, and when the correlation peak is smaller than a third preset threshold, continuing to perform correlation operation on the second subsequence and the third subsequence, and comparing the correlation peak obtained by the operation with the third preset threshold again until the frame header of the first preamble sequence in the first sequence is determined.

In the embodiment of the present invention, the terminal station 600 matches the received preamble sequence sent by the first terminal station with the preamble sequence corresponding to the frequency band supported by the PLC network, and determines the frequency band to be selected or switched, thereby implementing the function of the different-frequency networking of the PLC network, increasing the rate of selecting and switching the frequency band between the terminal stations in the PLC network, and reducing the time for the terminal stations to access the network.

It should be understood that the terminal station 600 according to the embodiment of the present invention may correspond to a second terminal station in the embodiment of the present invention, and the above and other operations and/or functions of each module in the terminal station 600 implement the corresponding flows of each method in fig. 3 to fig. 5, respectively, and are not described herein again for brevity.

Fig. 7 is a schematic structural diagram of a terminal station 700 according to an embodiment of the present invention. As shown in fig. 7, the terminal station 700 includes a memory 710 and a processor 720, wherein the memory 710 and the processor 720 communicate with each other via internal connection paths to transfer control and/or data signals.

The memory 710 is used for storing program codes;

the processor 720 is used for calling the program code to implement the method in the above embodiments of the present invention.

In an embodiment of the present invention, processor 720 may be a Central Processing Unit (CPU), a Network Processor (NP), or a combination of a CPU and an NP. The processor may further include a hardware chip. The hardware chip may be an application-specific integrated Circuit (ASIC), a Programmable Logic Device (PLD), or a combination thereof.

An embodiment of the present invention provides a computer-readable medium for storing a computer program code, where the computer program includes instructions for executing the method for selecting a frequency band according to the embodiment of the present invention in fig. 3 to 5. The readable medium may be a read-only memory (ROM) or a Random Access Memory (RAM), which is not limited in this respect.

Fig. 8 is a schematic frame diagram of an end station 800 according to an embodiment of the present invention, and as shown in fig. 8, the end station 800 includes:

a determining module 810, configured to determine an initial reference phase, where the initial reference phase is a phase of a subcarrier corresponding to any one of frequency bands supported by a PLC network for power line communication;

a generating module 820, configured to generate a first preamble sequence according to the initial reference phase, where the first preamble sequence is a preamble sequence corresponding to a frequency band of a signal sent by the PLC network at the current time;

a sending module 830, configured to send a first sequence to a second terminal station, where the first sequence includes the first preamble sequence.

It should be understood that the end station 800 may be any end station in the PLC network, for example, an upstream end station of two end stations that are out of communication, or an upstream end station of a newly-connected end station, for example, a first end station in the method 300.

Optionally, in some embodiments, the determining module 810 is further configured to determine a first reference phase according to the initial reference phase, where the first reference phase is a phase of a subcarrier corresponding to a frequency band of a signal sent at the current time in the PLC network.

Optionally, in some embodiments, the generating module 820 is configured to generate the first preamble sequence according to the first reference phase.

Optionally, in some embodiments, the determining module 810 is specifically configured to determine the length of the cyclic shift according to the number of frequency bands between the frequency band of the signal sent at the current time in the PLC network and the frequency band corresponding to the initial reference phase; and according to the length of the cyclic shift, performing cyclic shift on the initial reference phase to determine a first reference phase.

It should be understood that the terminal station 800 may also store only one of the preamble sequences corresponding to the frequency bands supported by the PLC network, and when the frequency band of the signal sent by the PLC network at the current time is different from the frequency band corresponding to the preamble sequence stored in the first terminal device, the signal can be obtained by performing different cyclic shifts on the phase of the preamble sequence stored in the first terminal station.

Optionally, in some embodiments, the preamble sequence pre-stored by the terminal station 800 may not be the preamble sequence corresponding to the frequency band supported by the PLC network, and may be any one of the preamble sequences, as long as the preamble sequence corresponding to the frequency band for transmitting the signal, that is, the first preamble sequence, may be obtained by performing phase according to the preamble sequence pre-stored by the first terminal station.

In the embodiment of the present invention, the determining module 810 determines the phases of different preamble sequences through cyclic shift, so as to obtain preamble sequences corresponding to different frequency bands, so that a terminal station does not need to store multiple preamble sequences, thereby saving the storage space of the terminal station, saving signaling overhead, and avoiding resource waste.

It should be understood that the terminal station 800 according to the embodiment of the present invention may correspond to the first terminal station in the embodiment of the present invention, and the above and other operations and/or functions of each module in the terminal station 800 implement the corresponding flows of each method in fig. 3 to fig. 5, respectively, and for brevity, are not described again here.

Fig. 9 is a schematic structural diagram of a terminal device 900 according to an embodiment of the present invention. As shown in fig. 9, the terminal device 900 includes a memory 910 and a processor 920, and the memory 910 and the processor 920 communicate with each other via an internal connection path to transmit control and/or data signals.

The memory 910 is used for storing program codes;

the processor 920 is configured to call the program code to implement the method in the above embodiments of the present invention.

In an embodiment of the present invention, the processor 920 may be a Central Processing Unit (CPU), a Network Processor (NP), or a combination of a CPU and an NP. The processor may further include a hardware chip. The hardware chip may be an application-specific integrated Circuit (ASIC), a Programmable Logic Device (PLD), or a combination thereof.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a U disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for selecting a frequency band in a power line communication network (PLC), the method comprising:

acquiring a first sequence sent by a first terminal station, wherein the first sequence comprises a first preamble sequence, and the first preamble sequence corresponds to a frequency band of a signal sent at the current moment;

matching the first preamble sequence with a pre-stored preamble sequence set to determine a target frequency band, wherein the target frequency band is a frequency band required to be selected; each pre-stored preamble sequence in the pre-stored preamble sequence set corresponds to a frequency band supported by a PLC network;

wherein the set of pre-stored preamble sequences comprises a first pre-stored preamble sequence and at least one other preamble sequence obtained by performing one or more cyclic shifts based on a phase of the first pre-stored preamble sequence.

2. The method of claim 1, wherein a length of the cyclic shift is determined according to a number of frequency bands supported by the PLC network.

3. The method of claim 1 or 2, wherein the matching the first preamble sequence with a set of pre-stored preamble sequences to determine a target frequency band comprises:

performing correlation operation on the first preamble sequence and each pre-stored preamble sequence in the set of pre-stored preamble sequences to determine a plurality of peak-to-average ratios;

determining a maximum peak-to-average ratio of the peak-to-average ratios larger than a first preset threshold value, and determining a frequency band corresponding to a pre-stored preamble sequence corresponding to the maximum peak-to-average ratio as the target frequency band.

4. The method of claim 1 or 2, wherein the matching the first preamble sequence with a set of pre-stored preamble sequences to determine a target frequency band comprises:

determining a maximum peak-to-average ratio of the plurality of peak-to-average ratios;

and determining the frequency band corresponding to the pre-stored lead code sequence corresponding to the maximum peak-to-average ratio as the target frequency band.

5. The method of claim 1 or 2, wherein prior to said matching the first preamble sequence with a set of pre-stored preamble sequences, the method further comprises:

determining whether the communication success rate with the first terminal station is smaller than a second preset threshold value;

and when the communication success rate is smaller than the second preset threshold, matching the first preamble sequence with the pre-stored preamble sequence set.

6. An end station, characterized in that the end station comprises:

an obtaining module, configured to obtain a first sequence sent by a first terminal station, where the first sequence includes a first preamble sequence, and the first preamble sequence corresponds to a frequency band of a signal sent at a current time;

a determining module, configured to match the first preamble sequence with a pre-stored preamble sequence set, and determine a target frequency band, where the target frequency band is a frequency band to be selected;

each pre-stored preamble sequence in the pre-stored preamble sequence set corresponds to a frequency band supported by a power line communication PLC network.

7. The station of claim 6, wherein the set of pre-stored preamble sequences comprises a first pre-stored preamble sequence, the first pre-stored preamble sequence is a pre-stored initial preamble sequence, a frequency band corresponding to the first pre-stored preamble sequence is a first frequency band, and the determining module is further configured to perform one or more cyclic shifts on a phase of the first pre-stored preamble sequence to obtain other preamble sequences in the set of pre-stored preamble sequences except for the first pre-stored preamble sequence.

8. The end station of claim 7, wherein the length of the cyclic shift is determined according to the number of frequency bands supported by the PLC network.

9. The terminal station according to claim 7 or 8, wherein the determining module is specifically configured to:

performing cyclic shift on the phase of the first pre-stored preamble sequence once to obtain a preamble sequence corresponding to a second frequency band;

and performing two times of cyclic shift on the phase of the first pre-stored preamble sequence to obtain a preamble sequence corresponding to a third frequency band.

10. The terminal station according to any of claims 6 to 8, wherein the determining module is specifically configured to:

determining the maximum peak-to-average ratio of the peak-to-average ratios which are larger than a first preset threshold value;

and determining a frequency band corresponding to the pre-stored preamble sequence corresponding to the maximum peak-to-average ratio as the target frequency band.

11. The terminal station according to any of claims 6 to 8, wherein the determining module is specifically configured to:

12. A terminal station according to any of claims 6 to 8, wherein the determining module is further configured to determine whether the communication success rate with the first terminal station is less than a second preset threshold;

the determining module is specifically configured to match the first preamble sequence with each pre-stored preamble sequence in the set of pre-stored preamble sequences when the communication success rate is smaller than the second preset threshold.

13. An apparatus for frequency band selection, comprising: the system comprises a processor and a transmission interface, wherein the processor receives or sends data through the transmission interface;

the processor is configured to invoke program instructions stored in the memory to perform a method of band selection as claimed in any one of claims 1 to 5.

14. A computer readable storage medium comprising program instructions which, when run on a computer or processor, cause the computer or processor to carry out a method of frequency band selection according to any one of claims 1 to 5.