An Extension of Wideband HF Capabilities

A Method of Estimating Sparse and Doubly-Dispersive Channels

“…We use the FBMC-SS waveform for its demonstrated robust performance at low-SNRs; e.g., [29], [30]. Similarly, we study the performance in HF channels because they are both doubly-dispersive and sparse in delay [2], and therefore pair well with the proposed channel estimation technique. Here, we provide a brief overview of the FBMC-SS waveform for completeness; see [16], [26], [30] for further details.…”

“…The simulated channel has two equal-power modes separated in time by 2 ms. Following [32] and [2], the PDP of each mode follows a Gamma distribution and each path fades with a Gaussian Doppler spectrum. The RMS delay spread of each mode is 80 µs and each path fades with a Doppler spread of 4 Hz (equivalently, a 2σ-width of 8 Hz).…”

“…Removing the time variation of the path delays m i is justified if we assume that the path delays appear in time-contiguous clusters, such as those in skywave HF channels [2].…”

“…A key observation for many communications systems is that channels are often sparse in delay; that is, the channel impulse response has only a small number of nonzero coefficients relative to the total delay spread. An example of such a channel is the skywave high-frequency (HF) channel, where the impulse response may endure for several milliseconds but contains only a few significant paths [2]. By incorporating foreknowledge of sparsity into a channel estimator, the resulting error and complexity of the estimate can be reduced simultaneously [3].…”

Wideband High Frequency (WBHF) for Anti-access Area-Denial (A2AD) Environments

“…In addition, an extension of WBHF has been designed and implemented to provide data rates up to 240 kbps using channel bandwidths between 30 and 48 kHz [3]. This work has been proposed to the HF TAC for consideration as another new appendix to MIL-STD-188-110C.…”