Sub-band division design method of power line OFDM system

Abstract

A sub-band division design method of a power line OFDM (Orthogonal Frequency Division Multiplexing) system comprises the following steps: separating a noise path from an effective path based on a time domain power delay spectrum, and calculating the frequency domain signal-to-noise ratio of each subcarrier through time-frequency domain conversion; the adaptive sub-band division comprises a continuous non-uniform mechanism: (a) a sub-carrier level iteration method: dynamically comparing a sub-carrier signal-to-noise ratio with a current sub-band mean value deviation, and determining a sub-band boundary; (b) sub-band region dichotomy: recursively dichotomizing a frequency band, and dividing sub-bands according to a signal-to-noise ratio deviation convergence condition of the current frequency band and the first half of the sub-band; according to the subcarrier cross distribution mechanism, subcarriers with the optimal signal-to-noise ratio are distributed in turn after sub-frequency bands are divided, and discrete cross distribution is achieved. According to the method, the problem of spectrum resource shortage in a power line channel frequency selective fading scene is solved, continuous non-uniform sub-band division (improving channel consistency in sub-bands) and multi-user service balanced distribution (discrete cross distribution) are supported, and the spectrum utilization rate and the adaptive processing performance of MIMO-OFDM systems and the like are remarkably optimized.

Description

Technical Field

[0001] The present invention relates to the field of power line communications, and in particular to a sub-band division design method for a power line OFDM system. Background Art

[0002] OFDM is a multi-carrier modulation technology that effectively mitigates channel fading caused by multipath by dividing the entire bandwidth into several mutually orthogonal subcarriers at regular intervals. Power line channels inherently exhibit strong frequency-selective fading, i.e., high-frequency attenuation. Adaptive technology dynamically groups subcarriers based on their channel characteristics, employing appropriate modulation schemes to improve spectrum utilization and enhance system performance. As demand for communications services increases, OFDM will be integrated with various technologies, leading to increasing scarcity of spectrum resources. Effective spectrum resource planning is essential. Furthermore, to improve system performance, the system must dynamically process subcarriers based on their characteristics. For example, in MIMO-OFDM systems, data transmission requires precoding. In channels with multipath fading, applying the same precoding to the entire bandwidth can lead to performance degradation. Therefore, it is necessary to divide the subcarriers into subbands based on their characteristics and apply different precoding to each subband.

[0003] The most common subband division mechanism is average division. Assuming the number of subcarriers is K and the subcarrier granularity is M, the subband is divided into ceil(K / M) subbands. This subband division mechanism has low computational complexity, but due to the complexity of the power line channel frequency domain response, this method cannot guarantee the rationality of the subband division. Therefore, dynamic adjustment based on the signal-to-noise ratio is required.

[0004] Generally speaking, dynamic subcarrier allocation is based on signal-to-noise ratio (SNR) estimation. First, the SNR of the entire frequency band is estimated. The number of subbands is gradually increased from 1 until the mean squared error between the SNR of the subcarriers within the subband and the actual SNR is less than a set threshold. The number of subcarriers in that subband is then used as the subband granularity, and the entire frequency band is evenly divided into subbands. In complex channel environments, uniform subband granularity is not ideal, resulting in significant differences in channel state information between subcarriers within a subband. Furthermore, in multi-user scenarios, subcarrier allocation for different users must balance their performance due to their varying service requirements. If subcarrier allocation simply aggregates a particular user's subcarriers, occupying a portion of the bandwidth, this may not fully meet service requirements. Therefore, a cross-subcarrier allocation approach is necessary. Subcarrier SNR estimation is also a key issue in adaptive modulation. Conventional use of the average SNR of subcarriers within a subband as the evaluation criterion is not adequate; accurate calculation of the subcarrier SNR is required.

[0005] It should be noted that the information disclosed in the above background technology section is only used to understand the background of this application, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0006] The main purpose of the present invention is to overcome the defects existing in the above background technology and provide a sub-band division design method for a power line OFDM system.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A subband partitioning design method for a power line OFDM system includes the following steps:

[0009] S1. Frequency-domain subcarrier SNR estimation: The noise path and effective path are separated based on the power delay spectrum of the time-domain channel response. The time-domain average noise power is calculated. The frequency-domain noise power is obtained by combining the time-frequency domain conversion relationship. The frequency-domain SNR of each subcarrier is then calculated.

[0010] S2. Based on the frequency domain subcarrier signal-to-noise ratio, use any of the following mechanisms to divide the subbands:

[0011] Continuous non-uniform partitioning mechanism: Dynamically partition subband boundaries using any of the following methods:

[0012] (a) Subcarrier-level iteration: Dynamically divides the subband boundary by iteratively comparing the deviation between the subcarrier signal-to-noise ratio and the current subband mean signal-to-noise ratio;

[0013] (b) Subband region bisection method: The frequency band is recursively divided by bisection, and the subband boundary is determined based on the deviation convergence condition between the average signal-to-noise ratio of the current frequency band and the average signal-to-noise ratio of the first half of the subband obtained by direct bisection;

[0014] Subcarrier cross-allocation mechanism: Divide the frequency band into sub-bands and allocate subcarriers with the best signal-to-noise ratio within the sub-band to each sub-band in turn, achieving discrete cross-distribution of subcarriers.

[0015] Furthermore, step S1 specifically includes:

[0016] Perform IFFT transformation on the channel frequency domain response to obtain the time domain channel response;

[0017] Calculate the power delay spectrum based on the time domain channel response and separate the noise path and effective path by amplitude sorting;

[0018] Calculate the time domain average noise power based on the noise path and convert it into frequency domain noise power through the time-frequency domain scaling relationship;

[0019] The signal-to-noise ratio of each subcarrier is calculated using the frequency domain subcarrier signal energy and frequency domain noise power.

[0020] In an optional implementation manner, the continuous non-uniform subband partitioning mechanism (a) subcarrier level iteration method includes:

[0021] Starting from the starting subcarrier, iteratively calculate the mean square error between the current subcarrier signal-to-noise ratio and the mean signal-to-noise ratio of the previous subcarrier;

[0022] When the mean square error exceeds the set threshold, the preceding subcarrier is divided into the current subband, and the iteration continues with the current subcarrier as the starting point of the new subband until all subcarriers are traversed.

[0023] Furthermore, the subband boundary dynamic division process specifically includes:

[0024] Initialize the subband index and starting subcarrier position;

[0025] Calculate the deviation of the signal-to-noise ratio of each subcarrier from the mean signal-to-noise ratio of the preceding subcarriers;

[0026] If the deviation exceeds the threshold, the current subband boundary is confirmed and the subband parameters are reset; otherwise, the current subband range is expanded and iteration continues.

[0027] In another optional implementation, the continuous non-uniform partitioning mechanism (b) sub-band region bisection method includes:

[0028] Starting from the complete frequency band, calculate the average signal-to-noise ratio of the current frequency band;

[0029] Divide the current frequency band into two and calculate the average signal-to-noise ratio of the first half of the frequency band;

[0030] If the mean square error between the average signal-to-noise ratio of the current frequency band and the average signal-to-noise ratio of the first half of the frequency band exceeds the threshold, the first half of the frequency band is recursively split until the convergence condition is met and the subband boundary is confirmed;

[0031] The above process is repeated from the next subcarrier at the end position of the subband until the entire frequency band is covered.

[0032] Furthermore, the recursive segmentation process specifically includes:

[0033] Initialize the sub-band starting position and current frequency band range;

[0034] Calculate the average signal-to-noise ratio of the current frequency band and determine the position of the equinox point;

[0035] By comparing the mean square error of the average signal-to-noise ratio of the current frequency band with the average signal-to-noise ratio of the previous half of the sub-band and the threshold, it is decided whether to continue splitting or confirming the sub-band.

[0036] In yet another optional implementation, the subcarrier cross allocation mechanism includes:

[0037] Based on the relationship between adjacent subcarriers, the subcarrier noise power is calculated using a sliding window segmentation method.

[0038] Divide the entire frequency band into several sub-bands according to a fixed granularity;

[0039] In each sub-band, the sub-carrier with the best signal-to-noise ratio is allocated in turn according to the sub-band priority until all sub-carriers in the sub-band are allocated.

[0040] Furthermore, the sliding window noise power calculation specifically includes:

[0041] For edge subcarriers, a fixed window with endpoints is used, and for center subcarriers, a symmetric window centered on the current subcarrier is used;

[0042] The local noise power is calculated based on the subcarrier channel response within the window.

[0043] Furthermore, the round-robin allocation process specifically includes:

[0044] Initialize sub-band index and sub-band index;

[0045] In the current sub-band, the sub-carrier corresponding to the maximum signal-to-noise ratio among the remaining sub-carriers is selected for each sub-band in turn;

[0046] The subband index is updated cyclically in the allocation order until the subband is allocated and the next subband iteration is started.

[0047] A computer program product includes a computer program, wherein when the computer program is executed by a processor, the sub-band partitioning design method of the power line OFDM system is implemented.

[0048] The present invention has the following beneficial effects:

[0049] The present invention addresses the spectrum resource optimization problem of the power line OFDM system and significantly improves the spectrum utilization efficiency and system performance through an innovative sub-band partitioning mechanism. Its core advantage lies in the use of a dynamic and accurate signal-to-noise ratio estimation method: based on the time domain power delay spectrum to separate the noise path and the effective path, the signal-to-noise ratio of each subcarrier is calculated in combination with the time-frequency domain conversion relationship, overcoming the problem of inaccurate traditional average signal-to-noise ratio evaluation and providing a reliable basis for sub-band partitioning. The adaptive sub-band partitioning method of the present invention effectively copes with complex channel environments and multi-service requirements. Among them, the sub-band boundaries are accurately divided based on dynamic signal-to-noise ratio estimation (ensuring consistency of channel characteristics within the sub-band) and sub-carrier allocation is optimized (discrete cross distribution), thereby improving the sub-band adaptive modulation / precoding efficiency and ultimately improving spectrum utilization. The present invention solves the problem of spectrum resource shortage in the scenario of frequency selective fading of power line channels, supports continuous non-uniform sub-band partitioning (improving channel consistency within the sub-band) and balanced allocation of multi-user services (discrete cross distribution), and significantly optimizes the spectrum utilization and adaptive processing performance of systems such as MIMO-OFDM. In summary, the present invention significantly optimizes the efficiency of spectrum resource planning in an environment with strong frequency selective fading of power lines, supports the differentiated processing requirements of multi-technology fusion scenarios such as MIMO-OFDM, and provides key technical support for improving system throughput and stability.

[0050] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is the basic process of sub-band division based on subcarrier signal-to-noise ratio in an embodiment of the present invention.

[0052] Figure 2 This is a method flow for designing non-uniform sub-band division based on subcarrier signal-to-noise ratio in an embodiment of the present invention.

[0053] Figure 3 This is the basic process of sub-band division based on the sub-band area signal-to-noise ratio in an embodiment of the present invention.

[0054] Figure 4 This is a design method flow for non-uniform sub-band partitioning based on sub-band area signal-to-noise ratio in an embodiment of the present invention.

[0055] Figure 5 This is the basic process of the sub-band division mechanism based on sub-carrier cross allocation in an embodiment of the present invention.

[0056] Figure 6 This is a design method flow for sub-band division based on sub-carrier cross-allocation in an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope of the present invention and its application.

[0058] With the increasing demand for communication services, OFDM technology is facing an increasingly scarce spectrum resource shortage in scenarios such as MIMO and multi-user. In particular, under channel conditions with multipath fading, different frequency bands need to be adaptively processed, so sub-band division is required. The present invention provides two sub-band division mechanisms for power line OFDM systems, a continuous non-uniform sub-band division mechanism and a sub-band division mechanism based on sub-carrier cross-allocation. When performing sub-band division, the frequency domain sub-carrier signal-to-noise ratio is first calculated and the average signal-to-noise ratio of the sub-band area within the frequency band is estimated. For the continuous non-uniform sub-band division mechanism, two design methods are considered. One is sub-band division based on sub-carrier signal-to-noise ratio. Starting from sub-carrier 1, sub-carriers that meet the conditions are gradually divided into a given sub-band. The other is division based on the average signal-to-noise ratio of the sub-band area, that is, the area with similar signal-to-noise ratio is divided into a sub-band, and the relationship between its signal-to-noise ratio and the sub-band signal-to-noise ratio is used to determine whether the conditions are met. If not, the frequency band area is reduced. The subband division mechanism of subcarrier cross-allocation fully considers the relationship between adjacent subcarriers when calculating the subcarrier signal-to-noise ratio. The subcarrier indexes in each subband are discretely cross-distributed across the entire frequency band. First, the frequency band is divided into several subbands, and the subcarriers in each subband are allocated to different subbands in turn.

[0059] See Figures 1 to 6 The embodiment of the present invention provides a sub-band partitioning design method for a power line OFDM system, comprising the following steps:

[0060] Step S1. Frequency domain subcarrier signal-to-noise ratio estimation: Separate the noise path and the effective path based on the power delay spectrum of the time domain channel response, calculate the time domain average noise power, and combine the time-frequency domain conversion relationship to obtain the frequency domain noise power, and then calculate the frequency domain signal-to-noise ratio of each subcarrier;

[0061] Step S2: Based on the frequency domain subcarrier signal-to-noise ratio, use any of the following mechanisms to divide the subbands:

[0062] Continuous non-uniform partitioning mechanism: Dynamically partition subband boundaries using any of the following methods:

[0063] (a) Subcarrier-level iteration: Dynamically divides the subband boundary by iteratively comparing the deviation between the subcarrier signal-to-noise ratio and the current subband mean signal-to-noise ratio;

[0064] (b) Subband region bisection method: The frequency band is recursively divided by bisection, and the subband boundary is determined based on the deviation convergence condition between the average signal-to-noise ratio of the current frequency band and the average signal-to-noise ratio of the first half of the subband obtained by direct bisection;

[0065] Subcarrier cross-allocation mechanism: Divide the frequency band into sub-bands and allocate subcarriers with the best signal-to-noise ratio within the sub-band to each sub-band in turn, achieving discrete cross-distribution of subcarriers.

[0066] In some embodiments, step S1 specifically includes: performing IFFT transformation on the channel frequency domain response to obtain the time domain channel response; calculating the power delay spectrum based on the time domain channel response, and separating the noise path and the effective path by amplitude sorting; calculating the time domain average noise power based on the noise path, and converting it into frequency domain noise power through the time-frequency domain scaling relationship; and calculating the signal-to-noise ratio of each subcarrier using the frequency domain subcarrier signal energy and the frequency domain noise power.

[0067] See Figure 1 and Figure 2 In an optional embodiment, the continuous non-uniform partitioning mechanism (a) subcarrier-level iteration method includes: starting from the starting subcarrier, iteratively calculating the mean square error between the current subcarrier signal-to-noise ratio and the mean signal-to-noise ratio of the preceding subcarriers; when the mean square error exceeds a set threshold, the preceding subcarrier is designated as the current subband, and iteration continues with the current subcarrier as the starting point of the new subband until all subcarriers are traversed. Furthermore, the dynamic subband boundary partitioning process specifically includes: initializing the subband index and the starting subcarrier position; calculating the deviation of its signal-to-noise ratio and the mean signal-to-noise ratio of the preceding subcarriers for each subcarrier; if the deviation exceeds the threshold, confirming the current subband boundary and resetting the subband parameters; otherwise, expanding the current subband range and continuing iteration.

[0068] See Figure 3 and Figure 4 In another optional embodiment, the continuous non-uniform division mechanism (b) sub-band area bisection method includes: starting from the entire frequency band, calculating the average signal-to-noise ratio of the current frequency band; dividing the current frequency band into two and calculating the average signal-to-noise ratio of the first half of the sub-band; if the mean square error between the average signal-to-noise ratio of the current frequency band and the average signal-to-noise ratio of the first half of the sub-band exceeds a threshold, recursively splitting the first half of the sub-band until the convergence condition is met and the sub-band boundary is confirmed; repeating the above process from the next subcarrier at the end position of the sub-band until the entire frequency band is covered. Furthermore, the recursive segmentation process specifically includes: initializing the sub-band starting position and the current frequency band range; calculating the average signal-to-noise ratio of the current frequency band and determining the position of the bisection point; and determining whether to continue splitting or confirming the sub-band by comparing the mean square error between the average signal-to-noise ratio of the current frequency band and the average signal-to-noise ratio of the first half of the sub-band with the threshold.

[0069] See Figure 5 and Figure 6In another optional embodiment, the subcarrier cross-allocation mechanism includes: sliding window noise power calculation: based on the relationship between adjacent subcarriers, the subcarrier noise power is calculated by using a sliding window segmentation; sub-band division: the entire frequency band is divided into several sub-bands according to a fixed granularity; polling allocation: within each sub-band, the subcarrier with the current optimal signal-to-noise ratio is allocated in turn according to the sub-band priority until all subcarriers in the sub-band are allocated. Furthermore, the sliding window noise power calculation specifically includes: using an endpoint fixed window for the edge subcarriers and a symmetric window centered on the current subcarrier for the center subcarriers; calculating the local noise power based on the subcarrier channel response within the window. Furthermore, the polling allocation process specifically includes: initializing the sub-band index and sub-band index; within the current sub-band, selecting the subcarrier corresponding to the maximum signal-to-noise ratio among the remaining subcarriers for each sub-band in turn; cyclically updating the sub-band index according to the allocation order until the sub-band is allocated and the next sub-band iteration is entered.

[0070] The following further describes specific embodiments of the present invention and examples of algorithm implementation thereof.

[0071] The subband division mechanism is based on subcarrier signal-to-noise ratio estimation. First, the frequency domain average noise power of the channel response of the entire frequency band is calculated. Then, the average noise power is subtracted from the subcarrier energy of the channel frequency domain response to obtain the subcarrier signal-to-noise ratio.

[0072] First, we introduce the calculation method of signal-to-noise ratio. Without loss of generality, we assume that the frequency domain response of the receiving port r and the transmitting port p in the subcarrier k and symbol s channel is where N r , N t , K and S represent the number of receiving ports, the number of transmitting ports, the number of subcarriers and the number of symbols respectively, and the IFFT transformation is performed to obtain the time domain channel response value

[0073]

[0074] in, is the actual time-domain channel response, is the noise vector, and N is the Fourier transform size. Afterwards, use The power delay spectrum is calculated as follows:

[0075]

[0076] η n The values are arranged from large to small Select the noise path and effective path. Assuming the effective path is L, the noise path is NL. The time domain average noise power is calculated as follows:

[0077]

[0078] According to the relationship between time and frequency domains, the frequency domain noise power is expressed as

[0079]

[0080] Then the total energy of the time domain channel is

[0081]

[0082] Then the average signal-to-noise ratio of the subcarrier in the frequency domain is expressed as

[0083]

[0084] The signal energy of subcarrier k in the frequency domain is calculated as follows

[0085]

[0086] Finally, the signal-to-noise ratio of frequency domain subcarrier k can be calculated as follows

[0087]

[0088] First, we introduce the design method of continuous non-uniform subband division based on the frequency domain subcarrier signal-to-noise ratio. Considering the power line OFDM system with K subcarriers, the frequency domain subcarrier signal-to-noise ratio (SNR) is calculated according to formula (8): k , k=1,2,...,K. Assume that the starting position of the subcarrier is k0, if the signal-to-noise ratio SNR of subcarrier k is k The signal-to-noise ratio of subcarriers k0 to k-1 The mean square error of the signal-to-noise ratio δ k If the value is less than the set threshold ε, subcarriers k0 to k belong to the same subband, otherwise subcarrier k is divided into the next subband. k It is expressed as follows

[0089]

[0090] Starting from the first subcarrier, calculate the mean square error δ2 between subcarrier 2 and subcarrier 1. If δ2 < ε, continue to calculate the mean square error δ3 between subcarrier 3 and the mean signal-to-noise ratio of subcarrier 1 and subcarrier 2, and so on. k >ε, then subcarriers 1 to k-1 belong to subband 1. Then, starting from subcarrier k, follow the same steps to obtain the subcarrier index of subband 2 until all K subcarriers are divided. The design method flow of continuous non-uniform subband division based on subcarrier signal-to-noise ratio is as follows:

[0091] Step 1: Initialize subband index j = 1, the granularity of subband j M j=0, calculate the signal-to-noise ratio SNR k , subcarrier

[0092] The starting position k0=1, k=2.

[0093] Step 2: Calculate δ according to formula (9) k .

[0094] Step 3: Determine δ k Is it greater than the threshold value ε? If it is satisfied, go to step 4, otherwise k=k+1, M j =M j +1,

[0095] Go to step 2.

[0096] Step 4: Get the subcarrier region of subband j as the subcarrier region from index k0 to k-1.

[0097] Step 5: If k<K, j=j+1, k0=k, go to step 2; otherwise, stop subband division.

[0098] The following describes a design method for subband division based on the average signal-to-noise ratio (SNR) of the subband area. Unlike the above-mentioned method based on the subcarrier SNR, this design method starts from the entire frequency band and gradually reduces the subband area. Considering a power line OFDM system with K subcarriers, first calculate the average SNR' of all K subcarriers in the entire frequency band according to formula (6). Then calculate the average SNR" of frequency band 1 from subcarrier 1 to floor (K / 2). If the mean square error of SNR' and SNR" is greater than the threshold value, then continue to divide frequency band 1 into two subbands, and take the first half of frequency band 3 to continue the SNR calculation and evaluation until the mean square error of the SNR of each frequency band and the SNR of the first half of the subband divided by the next level is less than the set value, that is, a subband area is obtained. Starting from the next subcarrier where the last subcarrier of the subband is located, to subcarrier K, repeat the above steps to determine the second subband until all subcarriers are divided. The design method of subband division based on the average SNR of the subband area is as follows:

[0099] Step 1: Initialize subband index j = 1, k0 = 1, k = K, and the granularity M of subband j j =K.

[0100] Step 2: Calculate the average signal-to-noise ratio (SNR') of subcarrier indexes k0 to k according to equation (6).

[0101] Step 3: k m =floor((k+k0) / 2).

[0102] Step 4: Calculate subcarrier indexes k0 to k according to equation (6) mThe average signal-to-noise ratio SNR".

[0103] Step 5: Determine whether the mean square error of SNR' and SNR" is less than the threshold value. If so, go to step 7, otherwise go to step 8.

[0104] Go to step 6.

[0105] Step 6: SNR' = SNR", M j =k m -k0+1, k=k m , go to step 3.

[0106] Step 7: Get the subband granularity of subband j as M j , the subcarrier region is from index k0 to k.

[0107] Step 8: k0 = M j +k0, if k0<K, j=j+1, k=K, go to step 2; otherwise, stop sub-band division.

[0108] The following describes a subband division design method based on cross-subcarrier allocation. The subcarrier indexes in each subband are not distributed in a continuous frequency band area, but are discretely cross-distributed across the entire frequency band. Assuming the number of terminals is J, a subband needs to be allocated for each terminal, that is, the number of subbands required is J. The channel response from the subcarrier to each terminal is different, so the corresponding signal-to-noise ratio will also be different. Prioritize the terminals, that is, sort the subbands. Here, the subband priority is defined in descending order of the subbands, that is, subband 1 has the highest priority and subband J has the lowest priority. The cross-subband division mechanism design method is as follows:

[0109] When performing cross subcarrier allocation, the frequency domain subcarrier signal-to-noise ratio of each terminal needs to be calculated first, and the SNR is calculated from the above subcarrier k signal-to-noise ratio. k During calculation, the noise power is calculated based on the entire frequency band and averaged. When there is selective fading in the channel or the channel environment is complex, the signal-to-noise ratio calculation will be inaccurate. Therefore, the relationship between adjacent subcarriers is fully considered when calculating the noise power. Set the sliding window length to L, and calculate the noise power of the subcarrier using the sliding window method. The specific method is:

[0110] For subcarrier index When , the noise power is calculated by the channel frequency domain response corresponding to the subcarriers {1,2,...,L}.

[0111] For subcarrier index When the subcarrier The corresponding channel frequency domain response is used to calculate the noise power.

[0112] For subcarrier index When , the noise power is calculated by the channel frequency domain response corresponding to the subcarriers {K-L+1,...,K}.

[0113] After calculating the noise power, calculate the signal-to-noise ratio of terminal j in the subcarrier frequency domain and subcarrier k respectively. And sort them, that is, the signal-to-noise ratio of terminal j is arranged in descending order That is, the subcarriers are sorted into {k j,1 ,k j,2 ,...,k j,K}. Divide the continuous subcarriers into Q subbands with a granularity of F, Q = ceil (K / F), and satisfy F is an integer multiple of the number of subbands J, and the number of subcarriers in the first Q-1 subbands is F. q =F, the number of carriers in the last sub-band of Q is F q =mod(K,Q), assuming that the subcarrier set of subband q is represented by Γ q For sub-band q, q = 1, 2, ..., Q, sub-carriers are allocated to sub-band 1 to sub-band J in turn, as follows:

[0114] Step 1: Initialize q=1.

[0115] Step 2: Initialize the subband index j = 1. When q < Q, the subband subcarrier index is Γ = {(q-1)·F q +1,...,q·F q}, otherwise the subcarrier index is Γ={K+1-F q ,...,K}. The subcarrier set in subband j is κ j , is an empty set, n=0.

[0116] Step 3: Find the subcarrier index k corresponding to the maximum subband signal-to-noise ratio in the subband q max ,Right now

[0117] Step 4: Remove subcarrier k from the index set Γ max , κ j =κ j ∪k max , if n<F q , n=n+1, j=mod(n,J)+1, go to step: 3; otherwise if q<Q, q=q+1, go to step 2, if q=Q, end subcarrier allocation.

[0118] Examples

[0119] The design method of non-uniform subband division based on subcarrier signal-to-noise ratio is as follows: Without loss of generality, assuming that the number of subcarriers is K, the SNR is calculated using formula (8) k , first start from the k0=1th subcarrier, calculate the mean square error value δ2 between subcarrier 2 and subcarrier 1, if δ2 < ε, then continue to calculate the mean square error δ3 between subcarrier 3 and the average signal-to-noise ratio of subcarrier 1 and subcarrier 2, and so on to subcarrier k. If at subcarrier k, δ k >ε, then subcarriers 1 to k-1 belong to subband j=1.

[0120] Then, starting from subcarrier k0=k, calculate the δ corresponding to subcarrier k+1 k+1 , assuming δ k+1 <ε, continue to calculate the δ corresponding to subcarrier k+2 k+2 , and so on to subcarrier k+M, if δ k+M >ε, then subcarriers k to k+M-1 belong to subband j=2.

[0121] Starting from subcarrier k0=M, the process is deduced in this way until all K subcarriers are allocated.

[0122] The design method of non-uniform sub-band division based on sub-band area signal-to-noise ratio is as follows:

[0123] Consider a power line OFDM system with K=411 subcarriers. First, set k0=1 and k=K=411. Calculate the average signal-to-noise ratio (SNR') of all 411 subcarriers in the entire frequency band from k0 to k according to formula (6). Then calculate the average signal-to-noise ratio (SNR") of frequency band 1 from subcarriers 1 to 205. If the mean square error (MSE) of SNR' and SNR" is greater than the threshold, frequency band 1 is further divided into two subbands. The first half of frequency band 2, i.e., subcarriers 1 to 102, is taken to continue the SNR calculation and evaluation. If the convergence condition is not met, the SNR of subcarriers 1 to 56 is calculated. If the mean square error of the SNR of subcarriers 1 to 102 and subcarriers 1 to 56 is less than the set value, the region of subband j=1 is obtained to be 1 to 102.

[0124] Continue to set k0 = 103, k = K = 411, calculate the average signal-to-noise ratio SNR' of the 309 subcarriers in the entire frequency band from k0 to k according to formula (6), and then calculate the average signal-to-noise ratio SNR' of subcarriers 103 to k m =floor((k+k0) / 2)=257, the average signal-to-noise ratio SNR" of frequency band 1, if the mean square error of SNR' and SNR" is greater than the threshold, continue to calculate the subcarriers 103 to k m= average signal-to-noise ratio of floor((k+k0) / 2)=180. If the signal-to-noise ratio of subcarriers 103 to 257 and the mean square error of subcarriers 103 to 180 are less than the set value, the area of subband j=2 is 103 to 257.

[0125] And so on, until all subcarriers are allocated.

[0126] The design method of sub-band division based on sub-carrier cross allocation is as follows:

[0127] Consider a power line OFDM system with K=11 subcarriers and 2 terminals, and the number of subbands to be allocated is J=2.

[0128] First, the subcarrier signal-to-noise ratio is calculated based on the window length L = 6. When the subcarrier index k is 1 or 2, the noise power is calculated using the channel frequency domain responses corresponding to the subcarriers {1, 2, ..., 6}. When the subcarrier index k is 3, 4, 5, 6, 7, and 8, the noise power is calculated using the channel frequency domain responses corresponding to the subcarriers {k-2, k-1, k, k+1, k+2, and k+3}. When the subcarrier index k is 9, 10, and 11, the noise power is calculated using the channel frequency domain responses corresponding to the subcarriers {6, 7, 8, 9, 10, and 11}.

[0129] Subcarriers 1 to 11 are divided into Q = 3 subbands. The first two subbands have 4 subcarriers, and the last subband has 3 subcarriers. The three subbands are {1, 2, 3, 4}, {5, 6, 7, 8}, and {9, 10, 11}. The signal-to-noise ratio (SNR) of the two terminals is calculated based on their frequency responses. Assume that the subcarrier indices corresponding to the SNRs of the two terminals in descending order are {4, 1, 3, 5, 2, 8, 10, 6, 9, 7, 11} and {3, 5, 6, 2, 1, 4, 9, 11, 10, 8, 7}, respectively.

[0130] When q = 1, the frequency band subcarrier indices are {1, 2, 3, 4}. Subcarrier allocation is performed alternately between the two subbands. For terminal 1, the maximum signal-to-noise ratio among subcarrier indices 1, 2, 3, and 4 corresponds to subcarrier 4. Therefore, subcarrier 4 is assigned to subband j = 1, and subcarrier 4 is removed. For terminal 2, the maximum signal-to-noise ratio among subcarrier indices 1, 2, and 3 corresponds to subcarrier 3. Therefore, subcarrier 3 is assigned to subband j = 2, and subcarrier 3 is removed. Allocation continues. For terminal 1, the maximum signal-to-noise ratio among subcarrier indices 1, 2 corresponds to subcarrier 1. Therefore, subcarrier 1 is assigned to subband j = 1, and subcarrier 1 is removed. Finally, subcarrier 2 is assigned to j = 2. Finally, subcarriers 1 and 4 in frequency band 1 are assigned to subband j = 1, and subcarriers 2 and 3 are assigned to subband j = 2.

[0131] When q = 2, the frequency band subcarrier indices are {5, 6, 7, 8}. Subcarrier allocation is performed alternately between the two subbands. For terminal 1, the maximum signal-to-noise ratio among subcarrier indices 5, 6, 7, and 8 corresponds to subcarrier 5. Therefore, subcarrier 5 is assigned to subband j = 1, and subcarrier 5 is removed. For terminal 2, the maximum signal-to-noise ratio among subcarrier indices 6, 7, and 8 corresponds to subcarrier 6. Therefore, subcarrier 6 is assigned to subband j = 2, and subcarrier 6 is removed. Allocation continues. For terminal 1, the maximum signal-to-noise ratio among subcarrier indices 7 and 8 corresponds to subcarrier 8. Therefore, subcarrier 8 is assigned to subband j = 1, and subcarrier 8 is removed. Finally, subcarrier 7 is assigned to j = 2. In frequency band 1, subcarriers 5 and 8 are assigned to subband j = 1, and subcarriers 6 and 7 are assigned to subband j = 2.

[0132] When q = 3, the frequency band subcarrier indices are {9, 10, 11}. Subcarriers are allocated to the two subbands in turn. For terminal 1, the maximum signal-to-noise ratio among subcarrier indices 9, 10, and 11 corresponds to subcarrier 10. Therefore, subcarrier 10 is assigned to subband j = 1, and subcarrier 10 is removed. For terminal 2, the maximum signal-to-noise ratio among subcarrier indices 9 and 11 corresponds to subcarrier 9. Therefore, subcarrier 9 is assigned to subband j = 2. Subcarrier 9 is removed, and finally, subcarrier 11 is assigned to subband j = 1. In frequency band 1, subcarriers 10 and 11 are assigned to subband j = 1, and subcarrier 9 is assigned to subband j = 2.

[0133] Finally, the subcarrier indexes for j=1 are {1, 4, 5, 8, 10, 11}, and the subcarrier indexes for j=2 are {2, 3, 6, 7, 9}.

[0134] In summary, the present invention provides a method for continuous non-uniform sub-band region division in power line transmission and a sub-band division method based on cross-subcarrier allocation. For the continuous non-uniform sub-band division mechanism, two design approaches are considered: one based on the subcarrier signal-to-noise ratio, and the other based on the average signal-to-noise ratio of the sub-band region. The sub-band division mechanism based on cross-subcarrier allocation fully considers the relationship between adjacent subcarriers when calculating the subcarrier signal-to-noise ratio, making the subcarrier signal-to-noise ratio calculation more reasonable.

[0135] An embodiment of the present invention further provides a storage medium for storing a computer program, which at least performs the above method when executed.

[0136] An embodiment of the present invention further provides a control device, comprising a processor and a storage medium for storing a computer program; wherein the processor is configured to execute at least the method described above when executing the computer program.

[0137] An embodiment of the present invention further provides a processor, which executes a computer program and at least performs the method described above.

[0138] The storage medium can be implemented by any type of non-volatile storage device, or a combination thereof. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic random access memory (FRAM), a flash memory (Flash Memory), a magnetic surface memory, an optical disc or a read-only optical disc (CD-ROM); the magnetic surface memory can be a magnetic disk memory or a magnetic tape memory. The storage medium described in the embodiments of the present invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0139] In the several embodiments provided by the present invention, it should be understood that the disclosed systems and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0140] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0141] In addition, all functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be separately used as a unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0142] Those skilled in the art will understand that all or part of the steps of the above-mentioned method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above-mentioned method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc. Various media that can store program codes.

[0143] Alternatively, if the above-mentioned integrated unit of the present invention is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic disks or optical disks.

[0144] The methods disclosed in the several method embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments.

[0145] The features disclosed in several product embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new product embodiments.

[0146] The features disclosed in several method or device embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0147] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. Those skilled in the art will recognize that, without departing from the scope of the present invention, several equivalent substitutions or obvious variations can be made, and the performance or use of the same should be considered to fall within the scope of protection of the present invention.

Claims

1. A sub-band partitioning design method for a power line OFDM system, characterized in that: The following steps are involved: S1. Frequency-domain subcarrier SNR estimation: The noise path and effective path are separated based on the power delay spectrum of the time-domain channel response. The time-domain average noise power is calculated. The frequency-domain noise power is obtained by combining the time-frequency domain conversion relationship. The frequency-domain SNR of each subcarrier is then calculated. S2. Based on the frequency domain subcarrier signal-to-noise ratio, use any of the following mechanisms to divide the subbands: Continuous non-uniform partitioning mechanism: Dynamically partition subband boundaries using any of the following methods: (a) Subcarrier-level iteration: Dynamically divides the subband boundary by iteratively comparing the deviation between the subcarrier signal-to-noise ratio and the current subband mean signal-to-noise ratio; (b) Subband region bisection method: The frequency band is recursively divided by bisection, and the subband boundary is determined based on the deviation convergence condition between the average signal-to-noise ratio of the current frequency band and the average signal-to-noise ratio of the first half of the subband obtained by direct bisection; Subcarrier cross-allocation mechanism: Divide the frequency band into sub-bands and allocate subcarriers with the best signal-to-noise ratio within the sub-band to each sub-band in turn, achieving discrete cross-distribution of subcarriers.

2. The subband division design method according to claim 1, wherein: Step S1 specifically includes: Perform IFFT transformation on the channel frequency domain response to obtain the time domain channel response; Calculate the power delay spectrum based on the time domain channel response and separate the noise path and effective path by amplitude sorting; Calculate the time domain average noise power based on the noise path and convert it into frequency domain noise power through the time-frequency domain scaling relationship; The signal-to-noise ratio of each subcarrier is calculated using the frequency domain subcarrier signal energy and frequency domain noise power.

3. The sub-band division design method according to claim 1, wherein: The continuous non-uniform subband partitioning mechanism (a) subcarrier level iteration method includes: Starting from the starting subcarrier, iteratively calculate the mean square error between the current subcarrier signal-to-noise ratio and the mean signal-to-noise ratio of the previous subcarrier; When the mean square error exceeds the set threshold, the preceding subcarrier is divided into the current subband, and the iteration continues with the current subcarrier as the starting point of the new subband until all subcarriers are traversed.

4. The subband division design method according to claim 3, wherein: The subband boundary dynamic division process specifically includes: Initialize the subband index and starting subcarrier position; Calculate the deviation of the signal-to-noise ratio of each subcarrier from the mean signal-to-noise ratio of the preceding subcarriers; If the deviation exceeds the threshold, the current subband boundary is confirmed and the subband parameters are reset; otherwise, the current subband range is expanded and iteration continues.

5. The sub-band division design method according to claim 1, wherein: The continuous non-uniform partitioning mechanism (b) sub-band region bisection method includes: Starting from the complete frequency band, calculate the average signal-to-noise ratio of the current frequency band; Divide the current frequency band into two and calculate the average signal-to-noise ratio of the first half of the frequency band; If the mean square error between the average signal-to-noise ratio of the current frequency band and the average signal-to-noise ratio of the first half of the frequency band exceeds the threshold, the first half of the frequency band is recursively split until the convergence condition is met and the subband boundary is confirmed; The above process is repeated from the next subcarrier at the end position of the subband until the entire frequency band is covered.

6. The sub-band division design method according to claim 5, wherein: The recursive segmentation process specifically includes: Initialize the sub-band starting position and current frequency band range; Calculate the average signal-to-noise ratio of the current frequency band and determine the position of the equinox point; By comparing the mean square error of the average signal-to-noise ratio of the current frequency band with the average signal-to-noise ratio of the previous half of the sub-band and the threshold, it is decided whether to continue splitting or confirming the sub-band.

7. The sub-band division design method according to claim 1, wherein: The subcarrier cross allocation mechanism includes: Based on the relationship between adjacent subcarriers, the subcarrier noise power is calculated using a sliding window segmentation method. Divide the entire frequency band into several sub-bands according to a fixed granularity; In each sub-band, the sub-carrier with the best signal-to-noise ratio is allocated in turn according to the sub-band priority until all sub-carriers in the sub-band are allocated.

8. The sub-band division design method according to claim 7, wherein: The sliding window noise power calculation specifically includes: For edge subcarriers, a fixed window with endpoints is used, and for center subcarriers, a symmetric window centered on the current subcarrier is used; The local noise power is calculated based on the subcarrier channel response within the window.

9. The sub-band division design method according to claim 7, wherein: The polling allocation process specifically includes: Initialize sub-band index and sub-band index; In the current sub-band, the sub-carrier corresponding to the maximum signal-to-noise ratio among the remaining sub-carriers is selected for each sub-band in turn; The subband index is updated cyclically in the allocation order until the subband is allocated and the next subband iteration is started.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the sub-band partitioning design method for a power line OFDM system according to any one of claims 1 to 9 is implemented.

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