Trust Function Based Spinal Codes over the Mobile Fading Channel between UAVs

Channel qualities between UAVs vary drastically due to the mobility of UAVs. Conventional channel coding relies on channel state information (CSI) estimation and active bit rate selection and thus cannot adapt well to such varying channel conditions. In contrast, rateless codes can achieve almost optimal bit rate under varying channel conditions without CSI estimation and explicit rate selection. In rateless codes, Spinal codes are one of the most prominent solutions and perform much better than other rateless codes over the mobile fading channel between UAVs. However, Spinal codes still face the challenge of error accumulation effect, which largely hurts the transmission efficiency. In this paper, we for the first time analyze the error accumulation effect and its impact on the performance of Spinal codes under mobile fading channel conditions between UAVs. Furthermore, we propose a model for helping the decoder estimate the quality of each received symbol. Based on such model, trust function based Spinal codes (TFSC) are then proposed. Its main idea is to treat received symbols differently according to their qualities so that those symbols with better qualities can contribute more to the decoding process. Simulation results demonstrate that TFSC can significantly mitigate the error accumulation effect and improve the efficiency of Spinal codes, which achieves 1.1x to 4.4x overall performance improvement when compared with Spinal codes over the mobile fading channel between UAVs.