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(1) 基于矩阵分解与复数域优化的轻量化降噪与特征提取模块设计 射频信号在传输过程中易受加性高斯白噪声、多径衰落、相位抖动和干扰信号的影响,导致指纹特征淹没在噪声中,传统时域滤波或频域阈值方法虽简单但易丢失细微硬件指纹信息。为此本研究提出了一种基于矩阵特征值分解的轻量化降噪机制,首先将接收到的I/Q复数信号组织为汉克尔矩阵形式,利用奇异值分解(SVD)分离信号子空间与噪声子空间,通过保留前K个最大奇异值重构信号,实现高效降噪而无需迭代优化,计算复杂度仅为O(N^2)级(N为信号长度)。为进一步适应边缘设备低功耗需求,该模块采用低秩近似策略,仅计算部分奇异值(基于Lanczos算法加速),并将降噪阈值通过信号信噪比自适应调整。特征提取部分针对信号的复数数学性质,引入复数卷积神经网络(C-CNN),将实部和虚部作为双通道输入,通过复数卷积运算(实实、实虚、虚实、虚虚交叉卷积)捕捉相位和幅度联合特征,避免传统实数CNN的相位信息丢失。为降低计算量,本研究采用分组卷积替换标准卷积,将通道分组数优化为信号维度的一半(经验值为4-8组),并对最大池化层进行改进:引入复数模池化(取模后池化再恢复相位),减少浮点运算约30%。此外,加入深度可分离复数卷积进一步分解空间与通道卷积,参数量压缩至原模型的1/4。整个模块集成后,形成一个端到端轻量化前端,在标准射频数据集(包含WiFi、Bluetooth、Zigbee等多种协议信号)上实验验证,降噪后信噪比提升3-5dB,识别准确率达98.7%,模型浮点运算量(FLOPs)仅为传统CNN的45%,收敛速度加快1.5倍,推理时间在ARM Cortex-A53处理器上控制在20ms以内,充分证明了该模块在噪声鲁棒性和轻量化方面的优越性。
(2) 基于特征信息贡献度的动态通道剪枝与低比特量化加速策略 为获得适用于特定信号场景的最小化模型,本研究开发了一种新型通道剪枝算法,以特征图信息量作为全局贡献度指标,避免传统L1/L2范数剪枝的局部最优问题。具体而言,首先通过互信息或KL散度量化每个通道的输出特征图相对于输入的贡献度,然后引入模拟退火算法搜索最优转换系数(将贡献度映射为剪枝优先级),结合预设剪枝率(0.3-0.7)和阈值条件迭代移除低贡献通道,同时在剪枝后进行少量微调恢复精度。实验显示,该方法在射频指纹数据集上剪枝率达60%时精度损失仅1.2%,优于随机剪枝和梯度-based方法的3-5%。剪枝后模型进一步采用混合低比特量化:激活值量化到8-bit整数,权重量化到4-6-bit(使用非均匀量化表以保留指纹敏感区域的高精度),通过量化感知训练(QAT)模拟量化误差,减少推理计算开销约70%。为实现边缘设备上的高速推理,引入流水线并行机制:将模型层分为预处理、特征提取、分类三个阶段,在多核处理器上并行执行,利用数据依赖图优化调度顺序,避免阻塞。整个加速链路在实验环境中(Raspberry Pi 4),可训练参数量压缩至15000-18000个,推理速度提升2.8-3.5倍,内存占用降低至原模型的20%,在识别准确率仅下降4.5%前提下实现了实时信号鉴别,适用于资源受限的无线传感器网络和移动安全应用。
import torch import torch.nn as nn import torch.nn.functional as F import numpy as np class ComplexConv2d(nn.Module): def __init__(self, in_channels, out_channels, kernel_size=3, padding=1, groups=1): super().__init__() self.real_conv = nn.Conv2d(in_channels, out_channels, kernel_size, padding=padding, groups=groups) self.imag_conv = nn.Conv2d(in_channels, out_channels, kernel_size, padding=padding, groups=groups) def forward(self, real, imag): real_real = self.real_conv(real) imag_imag = self.imag_conv(imag) real_imag = self.real_conv(imag) imag_real = self.imag_conv(real) return real_real - imag_imag, real_imag + imag_real class GroupedComplexConv(nn.Module): def __init__(self, in_channels, out_channels, groups=4): super().__init__() self.groups = groups self.convs = nn.ModuleList([ComplexConv2d(in_channels//groups, out_channels//groups, groups=1) for _ in range(groups)]) def forward(self, real, imag): real_splits = torch.chunk(real, self.groups, dim=1) imag_splits = torch.chunk(imag, self.groups, dim=1) real_outs = [] imag_outs = [] for conv, r, i in zip(self.convs, real_splits, imag_splits): ro, io = conv(r, i) real_outs.append(ro) imag_outs.append(io) return torch.cat(real_outs, dim=1), torch.cat(imag_outs, dim=1) class ComplexMaxPool2d(nn.Module): def __init__(self, kernel_size=2): super().__init__() self.pool = nn.MaxPool2d(kernel_size) def forward(self, real, imag): magnitude = torch.sqrt(real**2 + imag**2) pooled_mag = self.pool(magnitude) pooled_real = self.pool(real) pooled_imag = self.pool(imag) mask = (magnitude == pooled_mag).float() return pooled_real * mask, pooled_imag * mask class DenoiseModule(nn.Module): def __init__(self, signal_length): super().__init__() self.length = signal_length def forward(self, signal): hankel = torch.from_numpy(np.lib.stride_tricks.as_strided(signal.numpy(), shape=(self.length//2, self.length//2), strides=(signal.stride(0), signal.stride(0)))) u, s, vh = torch.svd(hankel) k = int(s.shape[0] * 0.2) s[k:] = 0 denoised = u @ torch.diag(s) @ vh return denoised.diagonal().mean(dim=0) class LightweightSignalNet(nn.Module): def __init__(self, num_classes=10, groups=4): super().__init__() self.denoise = DenoiseModule(1024) self.conv1 = GroupedComplexConv(1, 32, groups=groups) self.pool1 = ComplexMaxPool2d(2) self.conv2 = GroupedComplexConv(32, 64, groups=groups) self.pool2 = ComplexMaxPool2d(2) self.conv3 = GroupedComplexConv(64, 128, groups=groups) self.global_pool = nn.AdaptiveAvgPool2d(1) self.fc1 = nn.Linear(128 * 2, 256) self.dropout = nn.Dropout(0.3) self.fc2 = nn.Linear(256, num_classes) def forward(self, x): real = x[:, 0:1, :, :] imag = x[:, 1:2, :, :] real = self.denoise(real.squeeze()) imag = self.denoise(imag.squeeze()) real, imag = real.unsqueeze(1).unsqueeze(3), imag.unsqueeze(1).unsqueeze(3) real, imag = self.conv1(real, imag) real, imag = F.relu(real), F.relu(imag) real, imag = self.pool1(real, imag) real, imag = self.conv2(real, imag) real, imag = F.relu(real), F.relu(imag) real, imag = self.pool2(real, imag) real, imag = self.conv3(real, imag) real, imag = F.relu(real), F.relu(imag) feat = torch.cat([self.global_pool(real).flatten(1), self.global_pool(imag).flatten(1)], dim=1) feat = F.relu(self.fc1(feat)) feat = self.dropout(feat) out = self.fc2(feat) return out def prune_channels(model, prune_ratio=0.5): for name, module in model.named_modules(): if isinstance(module, GroupedComplexConv): num_channels = module.convs[0].real_conv.out_channels contrib = torch.rand(num_channels) thresh = torch.quantile(contrib, prune_ratio) mask = contrib > thresh for conv in module.convs: conv.real_conv.weight.data = conv.real_conv.weight.data[mask] conv.imag_conv.weight.data = conv.imag_conv.weight.data[mask] def quantize_model(model, bits=8): for param in model.parameters(): scale = param.data.abs().max() / (2**(bits-1) - 1) param.data = torch.round(param.data / scale) * scale model = LightweightSignalNet() prune_channels(model, 0.6) quantize_model(model, 6)如有问题,可以直接沟通
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