HF data link protocol RF simulator performance based on STANAG 4538 and STANAG 4539

STANAG 4538 (S4538) defines a pair of ARQ protocols that provide error free data transfer between HF terminals or nodes. These protocols utilize a form of code combining to automatically adapt to the conditions of the HF channel. The achievable throughput of these data link protocols is limited by the choice of the underlying waveform. STANAG 4539 (S4539) defines a set of high data rate HF modem waveforms that provide on-air data rates up to 12,800 bps. The data link protocols developed by Harris Corporation and discussed in this paper, HDL+, apply the code combining concepts to the higher capacity data waveforms of S4539. HDL+ is currently being considered by the NATO HF Radio Ad Hoc Working Group as an enhancement to S4538. The paper begins with an overview of the current definition of HDL+ highlighting several waveform level improvements that provide better throughput and lower latency than existing standard approaches, when channel conditions allow. The paper continues by presenting throughput performance measured on the AN/PRC-150C HF tactical radio using a hardware RF channel simulator setup comparing HDL+ with the data link protocol defined in S4538. The paper also presents comparison data of IP message load versus message delivered for a simple mesh network using the same RF Simulator setup.