LAHDC: Logic-Aggregation based Query for Embedded Hyperdimentional Computing Accelerator

With low complexity and robustness, hyperdimensional computing (HDC) has become a promising paradigm for edge-side applications. HDC employs hypervectors (generally with 2K-10K dimensions) to represent input samples, and performs logical operations in hyperdimensional space to complete perceptual tasks. Compared to deep neural network (DNN), HDC is more suitable for lightweight edge-side applications (i.e. speech, activity recognition), due to its low complexity and less computational scheduling. However, existing HDC’s querying process relies on trained class hypervectors, resulting in on-chip storage and transmission overhead which limits the application of ASIC-based or FPGA-based HDC accelerators in embedded systems. In this paper, a logic-aggregation based query method called LAHDC is proposed to eliminate such overhead. In addition, an ultra-tiny HDC accelerator design matching LAHDC is also proposed, as well as an automated tool to search for optimal structure and generate hardware design code. Experimental results show that, compared to existing ASIC-based HDC accelerators, the proposed design reduce the area/energy by more than 95%/80%.