A subband partition design method for power line OFDM systems

Abstract

A sub-band division design method of power line OFDM system, comprising: separating noise path and effective path based on time domain power time delay spectrum, calculating each sub-carrier frequency domain signal-to-noise ratio through time-frequency domain conversion; adaptive sub-band division, comprising: continuous non-uniform mechanism: (a) sub-carrier level iteration method: dynamically comparing sub-carrier signal-to-noise ratio with current sub-band mean deviation, determining sub-band boundary; (b) sub-band area dichotomy: recursive dichotomy of frequency band, dividing sub-band according to current frequency band and half sub-band signal-to-noise ratio deviation convergence condition; sub-carrier cross allocation mechanism: after dividing sub-band, alternately allocating optimal signal-to-noise ratio sub-carrier, realizing discrete cross distribution. The application solves the problem of spectrum resource shortage under the scenario of power line channel frequency selective fading, supports continuous non-uniform sub-band division (improving sub-band channel consistency) and multi-user service balanced allocation (discrete cross distribution), and significantly optimizes the spectrum utilization and adaptive processing performance of MIMO-OFDM system and the like.

Description

Technical Field

[0001] This invention relates to the field of power line communication, and in particular to a subband partitioning design method for a power line OFDM system. Background Technology

[0002] OFDM is a multi-carrier modulation technique that effectively combats channel fading caused by multipath propagation by dividing the entire bandwidth into several mutually orthogonal subcarriers with a certain subcarrier spacing. Power line channels inherently exhibit strong frequency-selective fading, i.e., high-frequency attenuation. Adaptive techniques can dynamically group subcarriers according to their channel characteristics, thereby adopting appropriate modulation methods to improve the utilization of the available spectrum and thus enhance system performance. With increasing demands for communication services, OFDM technology will be integrated with various other technologies, making spectrum resources increasingly scarce. Effective spectrum resource planning is essential. Simultaneously, to improve system performance, the system needs to dynamically process data based on the characteristics of the subcarriers themselves. For example, in a MIMO-OFDM system, precoding of transmitted data is required. Under multipath fading channel conditions, performing the same precoding across the entire bandwidth would lead to performance degradation. Therefore, it is necessary to divide the subcarriers into several subbands based on their characteristics and perform different precoding processes on each subband.

[0003] The most common subband partitioning mechanism is average partitioning, which assumes the number of subcarriers is K, and given the subcarrier granularity M, divides it into ceil(K / M) subbands. This subband partitioning mechanism has low computational complexity; however, due to the complexity of the frequency domain response of the power line channel, this method cannot guarantee the rationality of the subband partitioning, and therefore needs to be dynamically adjusted according to the signal-to-noise ratio.

[0004] Generally, 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 sub-bands is gradually increased from 1 until the mean square error between the SNR of the subcarriers within a sub-band and the actual SNR is less than a set threshold. Then, the number of subcarriers in that sub-band is used as the sub-band granularity to uniformly divide the entire frequency band. In complex channel environments, uniform sub-band granularity is not reasonable, as it can lead to significant differences in channel state information between subcarriers within a sub-band. Furthermore, in multi-user scenarios, due to the service requirements of different users, subcarrier allocation for different users needs to balance their performance. If the subcarrier allocation simply concentrates the subcarriers of a single user, occupying only a portion of the bandwidth, it may not fully meet service requirements. Therefore, a cross-subcarrier allocation method is necessary. Subcarrier SNR estimation is also a crucial issue in adaptive modulation. The conventional method of selecting the average SNR of subcarriers within a sub-band as the evaluation criterion is unsuitable; accurate subcarrier SNR calculation is required.

[0005] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The main objective of this invention is to overcome the deficiencies in the aforementioned background technology and provide a sub-band partitioning design method for power line OFDM systems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

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

[0009] S1. Frequency domain subcarrier signal-to-noise ratio estimation: Based on the power delay spectrum of the time domain channel response, the noise path and the effective path are separated, the time domain average noise power is calculated, and the frequency domain noise power is obtained by combining the time-frequency domain transformation relationship. Then, the frequency domain signal-to-noise ratio of each subcarrier is calculated.

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

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

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

[0013] (b) Subband region bisection method: The frequency band is recursively divided using the bisection method. The subband boundary is determined based on the convergence condition of the deviation 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: The frequency band is divided into sub-bands, and the subcarrier with the best signal-to-noise ratio in each sub-band is allocated in turn to achieve discrete cross-distribution of subcarriers.

[0015] Furthermore, step S1 specifically includes:

[0016] The time-domain channel response is obtained by performing an IFFT transform on the channel frequency domain response.

[0017] The power delay spectrum is calculated based on the time-domain channel response, and the noise path and effective path are separated by sorting by amplitude.

[0018] The time-domain average noise power is calculated based on the noise path, and then converted to the frequency-domain noise power using a time-frequency 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 one optional implementation, the continuous non-uniform subband partitioning mechanism (a) subcarrier-level iterative method includes:

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

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

[0023] Furthermore, the dynamic sub-band boundary partitioning process specifically includes:

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

[0025] The deviation of the signal-to-noise ratio (SNR) from the mean SNR of the preceding subcarrier is calculated for each subcarrier.

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

[0027] In another alternative 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 sub-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 sub-band exceeds the threshold, then the first half of the sub-band is recursively divided until the convergence condition is met and the sub-band boundary is confirmed.

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

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

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

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

[0035] By comparing the mean square error of the current frequency band's average signal-to-noise ratio with the mean square error of its average signal-to-noise ratio in the previous half of the sub-bands with the threshold, it is determined whether to continue dividing or confirming the sub-band.

[0036] In another alternative implementation, the subcarrier cross-allocation mechanism includes:

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

[0038] The entire frequency band is divided into several sub-bands with a fixed granularity.

[0039] Within each sub-band, the subcarrier with the best signal-to-noise ratio is allocated in turn according to the sub-band priority until all subcarriers within the sub-band are allocated.

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

[0041] A fixed endpoint window is used for edge subcarriers, and a symmetrical window centered on the current subcarrier is used for center subcarriers.

[0042] Calculate local noise power based on the subcarrier channel response within the window.

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

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

[0045] Within the current sub-band, select the subcarrier with the maximum signal-to-noise ratio among the remaining subcarriers for each sub-band in turn;

[0046] The subband index is updated cyclically according to the allocation order until the subband is fully allocated, and then the iteration moves to the next subband.

[0047] A computer program product includes a computer program that, when executed by a processor, implements the subband partitioning design method for the power line OFDM system.

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

[0049] This invention addresses the spectrum resource optimization problem in power line OFDM systems, significantly improving spectrum utilization efficiency and system performance through an innovative subband partitioning mechanism. Its core advantage lies in employing a dynamic and accurate signal-to-noise ratio (SNR) estimation method: based on separating the noise path and effective path from the time-domain power delay spectrum, and combining the time-frequency domain transformation relationship, the SNR of each subcarrier is calculated, overcoming the inaccuracy of traditional average SNR assessment and providing a reliable basis for subband partitioning. This invention's adaptive subband partitioning method effectively addresses complex channel environments and multi-service requirements. Specifically, it accurately partitions subband boundaries based on dynamic SNR estimation (ensuring consistent channel characteristics within subbands) and optimizes subcarrier allocation (discrete cross-distribution), thereby improving subband adaptive modulation / precoding efficiency and ultimately increasing spectrum utilization. This invention solves the spectrum resource scarcity problem in power line channel frequency-selective fading scenarios, supporting continuous non-uniform subband partitioning (improving channel consistency within subbands) and balanced multi-user service allocation (discrete cross-distribution), significantly optimizing the spectrum utilization and adaptive processing performance of systems such as MIMO-OFDM. In summary, this invention significantly optimizes spectrum resource planning efficiency in the context of strong frequency-selective fading of power lines, supports differentiated processing needs in scenarios integrating multiple technologies 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. Attached Figure Description

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

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

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

[0055] Figure 5 This is the basic process of the subband partitioning mechanism based on subcarrier cross-allocation in an embodiment of the present invention.

[0056] Figure 6 This is the design method flow for subband partitioning based on subcarrier cross-allocation in an embodiment of the present invention. Detailed Implementation

[0057] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0058] With the increasing demand for communication services, OFDM technology faces increasingly scarce spectrum resources in MIMO and multi-user scenarios, especially under channel conditions with multipath fading. Adaptive processing of different frequency bands is required, necessitating subband partitioning. This invention presents two subband partitioning mechanisms for power line OFDM systems: a continuous non-uniform subband partitioning mechanism and a subcarrier cross-allocation-based mechanism. When partitioning subbands, the frequency domain subcarrier signal-to-noise ratio (SNR) is calculated first, and the average SNR of the subband region within the frequency band is estimated. For the continuous non-uniform subband partitioning mechanism, two design methods are considered: one is subband partitioning based on subcarrier SNR, starting from subcarrier 1 and gradually allocating subcarriers that meet the conditions to a given subband; the other is partitioning based on the average SNR of the subband region, dividing regions with similar SNRs into a single subband, and determining whether the conditions are met by comparing the SNR of the subband with the subband's SNR. If not, the frequency band region 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 indices in each subband are discretely and cross-distributed throughout the frequency band. First, the frequency band is divided into several subbands, and the subcarriers in each subband are assigned to different subbands in turn.

[0059] See Figures 1 to 6 This invention provides a subband partitioning design method for a power line OFDM system, comprising the following steps:

[0060] Step S1. Frequency domain subcarrier signal-to-noise ratio estimation: Based on the power delay spectrum of the time domain channel response, the noise path and the effective path are separated, the time domain average noise power is calculated, and the frequency domain noise power is obtained by combining the time-frequency domain transformation relationship. Then, the frequency domain signal-to-noise ratio of each subcarrier is calculated.

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

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

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

[0064] (b) Subband region bisection method: The frequency band is recursively divided using the bisection method. The subband boundary is determined based on the convergence condition of the deviation 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: The frequency band is divided into sub-bands, and the subcarrier with the best signal-to-noise ratio in each sub-band is allocated in turn to achieve discrete cross-distribution of subcarriers.

[0066] In some embodiments, step S1 specifically includes: performing an IFFT transform 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 sorting by amplitude; 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 one optional implementation, the continuous non-uniform partitioning mechanism (a) subcarrier-level iterative method includes: starting from the initial subcarrier, iteratively calculating the mean square error between the signal-to-noise ratio (SNR) of the current subcarrier and the mean SNR 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. Further, the dynamic partitioning process of the subband boundary specifically includes: initializing the subband index and the position of the initial subcarrier; calculating the deviation between the SNR of each subcarrier and the mean SNR of the preceding subcarriers; if the deviation exceeds a 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 implementation, the continuous non-uniform partitioning mechanism (b) subband region bisection method includes: starting from the complete frequency band, calculating the average signal-to-noise ratio (SNR) of the current frequency band; bisecting the current frequency band and calculating the average SNR of the first half of the subband; if the mean square error between the average SNR of the current frequency band and the average SNR of the first half of the subband exceeds a threshold, then recursively partitioning the first half of the subband until the convergence condition is met and the subband boundary is confirmed; repeating the above process from the next subcarrier at the end of the subband until the entire frequency band is covered. Further, the recursive partitioning process specifically includes: initializing the subband start position and the current frequency band range; calculating the average SNR of the current frequency band and determining the bisection point position; and deciding whether to continue partitioning or confirm the subband by comparing the mean square error between the average SNR of the current frequency band and the average SNR of the first half of the subband with a threshold.

[0069] See Figure 5 and Figure 6In another optional implementation, the subcarrier cross-allocation mechanism includes: sliding window noise power calculation: calculating subcarrier noise power segmented by a sliding window based on the relationship between adjacent subcarriers; sub-band division: dividing the entire frequency band into several sub-bands with a fixed granularity; and round-robin allocation: allocating the current optimal signal-to-noise ratio subcarrier in turn according to sub-band priority within each sub-band until all subcarriers within the sub-band are allocated. Further, the sliding window noise power calculation specifically includes: using a fixed endpoint window for edge subcarriers and a symmetrical window centered on the current subcarrier for center subcarriers; calculating local noise power based on the channel response of the subcarriers within the window. Further, the round-robin allocation process specifically includes: initializing the sub-band index and sub-band index; sequentially selecting the subcarrier with the maximum signal-to-noise ratio among the remaining subcarriers for each sub-band within the current sub-band; cyclically updating the sub-band index according to the allocation order until the sub-band is fully allocated, then proceeding to the next sub-band iteration.

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

[0071] The subband partitioning mechanism is based on subcarrier signal-to-noise ratio estimation. First, the average noise power of the channel response of the entire frequency band is calculated in the frequency domain. 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 method for calculating the signal-to-noise ratio (SNR). Without loss of generality, we assume that the frequency domain response of the receiving port r and the transmitting port p in the channel with subcarrier k and symbol s is as follows: Where N r N t K and S represent the number of receive ports, the number of transmit ports, the number of subcarriers, and the number of symbols, respectively. An IFFT transform is performed on these components to obtain the time-domain channel response value.

[0073]

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

[0075]

[0076] η n Arrange the values ​​from largest to smallest to get Select the noise path and the effective path. Assuming the effective path is L, then the noise path is NL. The time-domain average noise power is calculated as follows:

[0077]

[0078] Based on the time-frequency domain relationship, the frequency domain noise power is expressed as follows:

[0079]

[0080] The total energy of the time-domain channel is

[0081]

[0082] The average signal-to-noise ratio of the subcarriers in the frequency domain is then expressed as:

[0083]

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

[0085]

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

[0087]

[0088] First, we introduce a design method for continuous non-uniform subband partitioning based on frequency domain subcarrier signal-to-noise ratio (SNR). Considering a power line OFDM system with K subcarriers, the SNR of the frequency domain subcarriers is calculated according to equation (8). k Let k = 1, 2, ..., K. Assume the subcarrier's starting position is k0. If the signal-to-noise ratio (SNR) of subcarrier k is... k Signal-to-noise ratio with subcarriers k0 to k-1 The mean square error δ of the signal-to-noise ratio k If the value is less than the set threshold ε, then subcarriers k0 to k belong to the same subband; otherwise, subcarrier k is assigned to the next subband. δ k It is expressed as follows

[0089]

[0090] Starting with the first subcarrier, calculate the mean square error δ2 between subcarrier 2 and subcarrier 1. If δ2 < ε, continue calculating the mean square error δ3 between subcarrier 3 and the mean signal-to-noise ratio of subcarrier 1 and subcarrier 2, and so on. If subcarrier k is... k If the signal-to-noise ratio (SNR) is greater than ε, then subcarriers 1 to k-1 belong to subband 1. Then, starting from subcarrier k, the subcarrier indices for subband 2 are obtained using the same steps, until all K subcarriers are divided. The design process for continuous non-uniform subband division based on subcarrier SNR is as follows:

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

[0092] The starting positions are k0 = 1 and k = 2.

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

[0094] Step 3: Determine δ k If the threshold value ε is greater than the threshold, proceed to step 4; otherwise, k = k + 1, M j =M j +1,

[0095] Proceed to step 2.

[0096] Step 4: Obtain 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 subband partitioning design method based on the average signal-to-noise ratio (SNR) of the subband region. Unlike the subcarrier SNR-based method described above, this design method starts from the entire frequency band and gradually reduces the subband region. Considering a power line OFDM system with K subcarriers, firstly, the average SNR' of all K subcarriers in the entire frequency band is calculated according to equation (6). Then, the average SNR" of frequency band 1 from subcarrier 1 to floor (K / 2) is calculated. If the mean square error between SNR' and SNR" is greater than the threshold value, then frequency band 1 is further divided into two sub-bands. The first half of frequency band 3 is taken and the SNR calculation and evaluation are continued until the mean square error between the SNR of each frequency band and the SNR of the first half of the sub-band divided by the next level is less than the set value, thus obtaining a subband region. Starting from the next subcarrier at the location of the last subcarrier of this subband, up to subcarrier K, the above steps are repeated to determine the second subband, until all subcarriers are partitioned. The subband partitioning design method based on the average SNR of the subband region is as follows:

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

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

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

[0102] Step 4: Calculate the subcarrier indices 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 it is, proceed to step 7; otherwise, proceed to step 8.

[0104] Proceed to step 6.

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

[0106] Step 7: Obtain the subband granularity of subband j as M. j The subcarrier region extends from index k0 to k.

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

[0108] The following describes a subband partitioning design method based on cross-carrier allocation. In this method, the subcarrier indices in each subband are not distributed across a continuous frequency band, but rather discretely and cross-distributed throughout the band. Assuming there are J terminals, each terminal needs its own subband, meaning J subbands are required. The channel response from each subcarrier to the terminal is different, resulting in different signal-to-noise ratios (SNRs). Terminals are prioritized, i.e., the subbands are sorted. Here, subband priorities are defined in descending order, with subband 1 having the highest priority and subband J having the lowest. The specific design method for the cross-subband partitioning mechanism is as follows:

[0109] When performing cross-subcarrier allocation, it is first necessary to calculate the frequency domain subcarrier signal-to-noise ratio (SNR) for each terminal, and then calculate the SNR from the aforementioned subcarrier k SNR. k During calculation, noise power is calculated based on the average value across the entire frequency band. However, in cases of selective fading or complex channel environments, this can lead to inaccurate signal-to-noise ratio (SNR) calculations. Therefore, the relationship between adjacent subcarriers must be fully considered when calculating noise power. The specific method for calculating subcarrier noise power using a sliding window with a sliding window length of L is as follows:

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

[0111] For subcarrier index is At that time, via subcarrier The noise power is calculated based on the corresponding channel frequency domain response.

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

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

[0114] Step 1: Initialize q = 1.

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

[0116] Step 3: Find the subcarrier index k corresponding to the maximum value of the subband signal-to-noise ratio in 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 If 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] Example

[0119] The design method based on non-uniform subband partitioning of subcarrier signal-to-noise ratio is illustrated in the following example: Without loss of generality, assuming the number of subcarriers is K, the SNR is calculated using equation (8). k First, starting with the k0=1 subcarrier, calculate the mean square error δ2 between subcarrier 2 and subcarrier 1. If δ2 < ε, then continue calculating the mean square error δ3 between subcarrier 3 and the average signal-to-noise ratio of subcarrier 1 and subcarrier 2, and so on up to subcarrier k. If at subcarrier k, δ k If ε > 1, then subcarriers 1 to k-1 belong to subband j = 1.

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

[0121] Starting with subcarrier k0 = M, and so on, until all K subcarriers have been allocated.

[0122] A design method for non-uniform subband partitioning based on subband region signal-to-noise ratio is illustrated in the following specific implementation:

[0123] Considering a power line OFDM system with K=411 subcarriers, first set k0=1, k=K=411, calculate the average signal-to-noise ratio (SNR') of all 411 subcarriers from k0 to k according to equation (6), then calculate the average SNR" of frequency band 1 from subcarrier 1 to 205. If the mean square error between SNR' and SNR" is greater than the threshold value, then continue to divide frequency band 1 into two sub-bands, take the first half of frequency band 2, that is, subcarrier 1 to 102, and continue to calculate and evaluate the SNR. If the convergence condition is not met, continue to calculate the SNR of subcarrier 1 to 56. If the mean square error between the SNR of subcarrier 1 to 102 and the mean square error of subcarrier 1 to 56 is less than the set value, then the region of subband j=1 is 1 to 102.

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

[0125] This process continues until all subcarriers have been allocated.

[0126] The subband partitioning design method based on subcarrier cross-allocation is illustrated in the following specific implementation:

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

[0128] First, the subcarrier signal-to-noise ratio (SNR) is calculated based on the window length L = 6. For subcarrier indices k = 1, 2, the noise power is calculated using the channel frequency response corresponding to subcarriers {1, 2, ..., 6}. For subcarrier indices k = 3, 4, 5, 6, 7, 8, the noise power is calculated using the channel frequency response corresponding to subcarriers {k-2, k-1, k, k+1, k+2, k+3}. For subcarrier indices k = 9, 10, 11, the noise power is calculated using the channel frequency response corresponding to subcarriers {6, 7, 8, 9, 10, 11}.

[0129] Subcarriers 1 to 11 are divided into Q = 3 sub-bands. The first two sub-bands have 4 subcarriers each, and the last sub-band has 3 subcarriers each. Therefore, the three sub-bands are {1,2,3,4}, {5,6,7,8}, and {9,10,11}. The signal-to-noise ratio (SNR) of each terminal is calculated based on its frequency response. Assume that the subcarrier indices corresponding to the descending SNR of the two terminals 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 subcarrier indices of the frequency band are {1,2,3,4}. Subcarriers are allocated to the two subbands alternately. For terminal 1, the maximum signal-to-noise ratio (SNR) among subcarrier indices 1, 2, 3, 4 corresponds to subcarrier 4, so subcarrier 4 is allocated to subband j=1. Subcarrier 4 is then removed. For terminal 2, the maximum SNR among subcarrier indices 1, 2, 3 corresponds to subcarrier 3, so subcarrier 3 is allocated to subband j=2. Subcarrier 3 is then removed, and the allocation continues. For terminal 1, the maximum SNR among subcarrier indices 1, 2 corresponds to subcarrier 1, so subcarrier 1 is allocated to subband j=1. Subcarrier 1 is then removed, and finally, subcarrier 2 is allocated to j=2. Therefore, in frequency band 1, subcarriers 1 and 4 are allocated to subband j=1, and subcarriers 2 and 3 are allocated to subband j=2.

[0131] When q=2, the subcarrier indices are {5,6,7,8}. Subcarrier allocation is performed alternately between the two subbands. For terminal 1, the subcarrier with the highest signal-to-noise ratio (SNR) among subcarrier indices 5, 6, 7, and 8 is subcarrier 5, so it is allocated to subband j=1. Subcarrier 5 is then removed. For terminal 2, the subcarrier with the highest SNR among subcarrier indices 6, 7, and 8 is subcarrier 6, so it is allocated to subband j=2. Subcarrier 6 is then removed, and allocation continues. For terminal 1, the subcarrier with the highest SNR among subcarrier indices 7 and 8 is subcarrier 8, so it is allocated to subband j=1. Subcarrier 8 is then removed, and finally, subcarrier 7 is allocated to j=2. Therefore, in frequency band 1, subcarriers 5 and 8 are allocated to subband j=1, and subcarriers 6 and 7 are allocated to subband j=2.

[0132] When q = 3, the subcarrier indices of the frequency band are {9, 10, 11}. Subcarriers are allocated to the two subbands alternately. For terminal 1, the subcarrier with the highest signal-to-noise ratio (SNR) among subcarrier indices 9, 10, and 11 is subcarrier 10. Therefore, subcarrier 10 is allocated to subband j = 1, and subcarrier 10 is removed. For terminal 2, the subcarrier with the highest SNR among subcarrier indices 9 and 11 is subcarrier 9. Therefore, subcarrier 9 is allocated to subband j = 2, and subcarrier 9 is removed. Finally, subcarrier 11 is allocated to subband j = 1. Thus, in frequency band 1, subcarriers 10 and 11 are allocated to subband j = 1, and subcarrier 9 is allocated to subband j = 2.

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

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

[0135] This invention also provides a storage medium for storing a computer program, which, when executed, performs at least the methods described above.

[0136] This invention also provides a control device, including a processor and a storage medium for storing a computer program; wherein the processor executes the computer program by performing at least the method described above.

[0137] This invention also provides a processor that executes a computer program, at least performing the methods described above.

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

[0139] In the several embodiments provided by this 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 units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or 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 various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

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

[0141] In addition, in the various embodiments of the present invention, each functional unit can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in 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 method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0143] Alternatively, if the integrated units of this invention are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROM, RAM, magnetic disks, or optical disks.

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

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

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

[0147] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or application, should be considered within the scope of protection of the present invention.

Claims

1. A subband partitioning design method for a power line OFDM system, characterized in that, Includes the following steps: S1. Frequency Domain Subcarrier Signal-to-Noise Ratio Estimation: Based on the power delay spectrum of the time-domain channel response, noise paths and effective paths are separated, the time-domain average noise power is calculated, and the frequency-domain noise power is obtained by combining the time-frequency domain transformation relationship. Then, the frequency domain signal-to-noise ratio of each subcarrier is calculated. Specifically, step S1 includes: performing an IFFT transform 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 paths and effective paths by sorting them by amplitude; calculating the time-domain average noise power based on the noise paths, and converting it to 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 frequency-domain noise power. S2. Based on the frequency domain subcarrier signal-to-noise ratio, subbands are divided using any of the following mechanisms: Continuous non-uniform partitioning mechanism: Dynamically partition sub-band boundaries using any of the following methods: (a) Subcarrier-level iterative method: The subband boundary is dynamically divided by iteratively comparing the deviation between the subcarrier signal-to-noise ratio and the mean signal-to-noise ratio of the current subband; (b) Subband region bisection method: The frequency band is recursively divided using the bisection method. The subband boundary is determined based on the convergence condition of the deviation 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: The frequency band is divided into sub-bands, and the subcarrier with the best signal-to-noise ratio in each sub-band is allocated in turn to achieve discrete cross-distribution of subcarriers.

2. The sub-band partitioning design method as described in claim 1, characterized in that, The continuous non-uniform partitioning mechanism (a) subcarrier-level iterative method includes: Starting from the initial subcarrier, iteratively calculate the mean square error between the signal-to-noise ratio of the current subcarrier and the mean signal-to-noise ratio of the preceding subcarrier; When the mean square error exceeds the set threshold, the preceding subcarrier is designated as the current subband, and the iteration continues with the current subcarrier as the starting point of the new subband until all subcarriers have been traversed.

3. The sub-band partitioning design method as described in claim 2, characterized in that, The dynamic partitioning process of subband boundaries specifically includes: Initialize the subband index and the starting subcarrier position; The deviation of the signal-to-noise ratio (SNR) from the mean SNR of the preceding subcarrier is calculated for each subcarrier. If the deviation exceeds the threshold, the current sub-band boundary is confirmed and the sub-band parameters are reset; otherwise, the current sub-band range is expanded and iteration continues.

4. The sub-band partitioning design method as described in claim 1, characterized in that, 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 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 the threshold, then the first half of the sub-band is recursively divided until the convergence condition is met and the sub-band boundary is confirmed. The above process is repeated starting from the next subcarrier at the end of the subband until the entire frequency band is covered.

5. The sub-band partitioning design method as described in claim 4, characterized in that, The recursive segmentation process specifically includes: Initialize the sub-band start position and the current frequency band range; Calculate the average signal-to-noise ratio of the current frequency band and determine the bisection point location; By comparing the mean square error of the current frequency band's average signal-to-noise ratio with the mean square error of its average signal-to-noise ratio in the previous half of the sub-bands with the threshold, it is determined whether to continue dividing or confirming the sub-band.

6. The subband partitioning design method as described in claim 1, characterized in that, The subcarrier cross-allocation mechanism includes: Based on the relationship between adjacent subcarriers, the subcarrier noise power is calculated in segments using a sliding window. The entire frequency band is divided into several sub-bands with a fixed granularity. Within each sub-band, the subcarrier with the best signal-to-noise ratio is allocated in turn according to the sub-band priority until all subcarriers within the sub-band are allocated.

7. The sub-band partitioning design method as described in claim 6, characterized in that, The calculation of sliding window noise power specifically includes: A fixed endpoint window is used for edge subcarriers, and a symmetrical window centered on the current subcarrier is used for center subcarriers. Calculate local noise power based on the subcarrier channel response within the window.

8. The sub-band partitioning design method as described in claim 6, characterized in that, The polling allocation process specifically includes: Initialize the sub-band index and sub-band index; Within the current sub-band, select the subcarrier with the maximum signal-to-noise ratio among the remaining subcarriers for each sub-band in turn; The subband index is updated cyclically according to the allocation order until the subband is fully allocated, and then the iteration moves to the next subband.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the subband partitioning design method for the power line OFDM system as described in any one of claims 1 to 8.

Images