We propose SCENE (Self-Centering Noncoherent Estimator), a pilot-free and phase-invariant aggregation primitive for over-the-air federated distillation (OTA-FD). Each device maps its soft-label (class-probability) vector to nonnegative transmit energies under constant per-round power and constant-envelope signaling (PAPR near 1). At the server, a self-centering energy estimator removes the noise-energy offset and yields an unbiased estimate of the weighted soft-label average, with variance decaying on the order of 1/(SM) in the number of receive antennas M and repetition factor S. We also develop a pilot-free ratio-normalized variant that cancels unknown large-scale gains, provide a convergence bound consistent with coherent OTA-FD analyses, and present an overhead-based crossover comparison. SCENE targets short-coherence and hardware-constrained regimes, where avoiding per-round CSI is essential: it trades a modest noncoherent variance constant for zero uplink pilots, unbiased aggregation, and hardware-friendly transmission, and can outperform coherent designs when pilot overhead is non-negligible.

翻译：我们提出了SCENE（自定心非相干估计器），一种用于空中联邦蒸馏的无导频且相位不变的聚合原语。每个设备在恒定每轮功率和恒包络信号（峰均功率比接近1）的条件下，将其软标签（类别概率）向量映射为非负的发射能量。在服务器端，一个自定心能量估计器移除了噪声能量偏移，并产生加权软标签平均值的无偏估计，其方差随接收天线数M和重复因子S以1/(SM)的量级衰减。我们还开发了一种无导频的比率归一化变体，以消除未知的大尺度增益；提供了一个与相干OTA-FD分析一致的收敛界；并进行了基于开销的交叉点比较。SCENE针对短相干时间和硬件受限的场景，其中避免每轮信道状态信息至关重要：它以适度的非相干方差常数为代价，换取了零上行导频、无偏聚合和硬件友好的传输，并且在导频开销不可忽略时能够超越相干设计方案。