Citation
Abstract
In this report, we describe proof-of-concept test results for the use of the Disruption-Tolerant Networking (DTN) Licklider Transmission Protocol (LTP) for the automatic determination of optimum coding and modulation strategies for the JPL Space Telecommunications Radio System (STRS) that is on the ISS as part of the SCaN Testbed. Under a SCaN Technology task, Variable Coded Modulation (VCM) modes [1] were implemented in an FPGA system for installation in the STRS radio on the ISS. These modes, described in [1], consist of combinations of modulation types (BPSK through 64APSK) and LDPC, C2, and Turbo codes of various rates. The flight test of several modulation types in the JPL STRS radio was reported in IPN Progress Report 42-212, dated February 15, 2018. Subsequent ground tests on the STRS field programmable gate array (FPGA) hardware used for development of the VCM capabilities successfully demonstrated the VCM coding and modulation strategies defined in [1]. Given the large number of new coding and modulation combinations in the specification, a means of automating selection of the appropriate mode is desired to make the system truly adaptive to changing link conditions. In this report, we describe the emulation experiments conducted using LTP segment retransmission statistics to make decisions in the radio as to which VCM mode is optimum, showing the data throughput trades between LTP retransmissions on a lossy channel and changing to a lower-rate code to eliminate errors.
Details
- Volume
- 42-217
- Published
- May 15, 2019
- Pages
- 1–16
- File Size
- 375 KB