A Study of Cross-Layer BP/LTP Data Block Size in Space Vehicle Communications Over Lossy and Highly Asymmetric Channels

Abstract

The bundle protocol (BP) and Licklider transmission protocol (LTP) were developed to provide reliable and highly efficient data delivery over unreliable space vehicle communication channels. Some preliminary studies on cross-layer BP/LTP data block size in space vehicle communications have been done. However, the effect of data losses on the block has been ignored. Data loss caused by lossy space channels is one of the key features that characterize space vehicle communications, and therefore its effect cannot be left out. In this article, the cross-layer BP/LTP block size in space vehicle communications is studied with focus on its characterization and performance over lossy space channels. An analytical model is presented for calculating the minimum number of bundles that should be aggregated within an LTP block for transmission over a lossy channel so that the report segment (RS) delay imposed by highly asymmetric channel rates can be resolved. The model is validated by realistic file transfer experiments over an experimental testbed infrastructure and packet-level analysis of the results. The transmission performance of LTP with respect to variations of the aggregated block size, channel date rate and channel loss rate are discussed.