What is claimed is:1. A radio-frequency (RF) repeater configured for semantic-less retransmissions, the RF repeater comprising:processing circuitry; and memory,wherein the processing circuitry is to:perform physical (PHY) layer processing to identify one or more residual indicators present in a received RF signal; anddetermine whether or not to retransmit the received RF signal based solely on the one or more residual indicators,wherein the residual indicators result from an electromagnetic transmission of the received RF signal by a transmitter performing one or more of upconversion, modulation and amplification,wherein the processing circuitry is to refrain from performing processing at any one or more logical layers higher than a PHY layer, including refraining from performing medium access control (MAC) layer processing to determine whether or not to retransmit the received RF signal,wherein the processing circuitry is to:authenticate the received RF signal based on one or more authentication features determined from the residual indicators;determine, if the received RF signal is authenticated, whether or not to retransmit the received RF signal based on one or more retransmission features determined from the residual indicators; andrefrain from retransmitting the received RF signal when not authenticated,wherein the one or more authentication features and the one or more retransmission features are stored in the memory.2. The RF repeater of claim 1, wherein to refrain from performing MAC layer processing, the processing circuitry is to refrain from bit parsing, decoding or reading packet headers and IP addresses to determine whether to retransmit the RF signal.3. The RF repeater of claim 1, wherein the processing circuitry is further configured to determine the one or more authentication features using in-phase (I) and quadrature-phase (Q) samples generated from the received RF signal, andwherein the one or more authentication features comprise an error vector magnitude of the I and Q samples and a local-oscillator (LO) signal presence in the received RF signal.4. The RF repeater of claim 3, wherein the one or more authentication features further comprise one or more of: a modulation type, a chip rate, a chip-set identifier, a signal rise time, and an I-Q symbol error determined from the received RF signal.5. The RF repeater of claim 3, wherein the processing circuitry is further configured to authenticate the received RF signal based on RF fingerprinting using an RF machine learning (RFML) technique using the I and Q samples.6. The RF repeater of claim 3, wherein the retransmission features comprise: an I-Q sample region and a signal-to-noise ratio (SNR) of the received RF signal,wherein the processing circuitry is configured to determine whether or not to retransmit the received RF signal:when the I and Q samples of the received RF signal fall within the I-Q sample region, andwhen the SNR of the received RF signal is within a predetermined SNR range.7. The RF repeater of claim 6, wherein prior to remodulation of the I and Q samples for retransmission of the received RF signal, the processing circuitry is to process the I and Q samples to remove noise and interference.8. The RF repeater of claim 3, wherein the RF repeater further comprises receiver circuitry to demodulate the received RF signal to generate the I and Q samples of the received RF signal, andwherein the processing circuitry comprises a baseband processor.9. The RF repeater of claim 3, wherein the RF repeater is configured for operation as a node in a multi-hop network, the processing circuitry is configured to cause the RF repeater to route the received RF signal to a next-hop node when authenticated based on the residual indicators.10. The RF repeater of claim 1, wherein the processing circuitry and memory comprises a field-programmable gate array (FPGA).11. A method for semantic-less retransmissions comprising:performing physical (PHY) layer processing to identify one or more residual indicators present in a received RF signal; anddetermining whether or not to retransmit the received RF signal based on the one or more residual indicators,wherein the residual indicators result from an electromagnetic transmission of the received RF signal by a transmitter performing one or more of upconversion, modulation and amplification,wherein the method further comprises:refraining from performing processing at any one or more logical layers higher than a PHY layer, including refraining from performing medium access control (MAC) layer processing to determine whether or not to retransmit the received RF signal;authenticating the received RF signal based on one or more authentication features determined from the residual indicators;determining, if the received RF signal is authenticated, whether or not to retransmit the received RF signal based on one or more retransmission features determined from the residual indicators; andrefraining from retransmitting the received RF signal when not authenticated.12. The method of claim 11, wherein performing the PHY layer processing comprises generating in-phase Wand quadrature-phase (Q) samples of the received RF signal, andwherein the method comprises:authenticating the received RF signal based on one or more authentication features determined from the residual indicators determined from the I and Q samples; andif the received RF signal is authenticated, determining whether or not to retransmit the received RF signal based on one or more retransmission features determined from the residual indicators determined from the I and Q samples.13. The method of claim 12, wherein the one or more authentication features comprise an error vector magnitude of the I and Q samples and a local-oscillator (LO) signal presence in the received RF signal.14. The method of claim 13, wherein the retransmission features comprise: an I-Q sample region and a signal-to-noise ratio (SNR) of the received RF signal,wherein the method further comprises determining whether or not to retransmit the received RF signal:when the I and Q samples of the received RF signal fall within the I-Q sample region, andwhen the SNR of the received RF signal is within a predetermined SNR range.15. The method of claim 14, further comprising:processing the I and Q samples to remove noise and interference; andre modulating the I and Q samples for retransmission of the received RF signal after processing.16. A non-transitory computer-readable storage medium that stores instructions for execution by processing circuitry of an RF repeater configured for semantic-less retransmissions, wherein the processing circuitry is configured to:perform physical (PHY) layer processing to identify one or more residual indicators present in of a received RF signal; anddetermine whether or not to retransmit the received RF signal based on the one or more residual indicators,wherein the residual indicators result from an electromagnetic transmission of the received RF signal by a transmitter performing one or more of upconversion, modulation and amplification,wherein the processing circuitry is to:refrain from performing processing at any one or more logical layers higher than a PHY layer, including refraining from performing medium access control (MAC) layer processing to determine whether or not to retransmit the received RF signal;authenticate the received RF signal based on one or more authentication features determined from the residual indicators;determine, if the received RF signal is authenticated, whether or not to retransmit the received RF signal based on one or more retransmission features determined from the residual indicators; andrefrain from retransmitting the received RF signal when not authenticated.17. The non-transitory computer-readable storage medium of claim 16, wherein the processing circuitry is further configured to determine the one or more authentication features using in-phase (I) and quadrature-phase (Q) samples generated from the received RF signal,wherein the one or more authentication features comprise an error vector magnitude of the I and Q samples and a local-oscillator (LO) signal presence in the received RF signal,wherein the retransmission features comprise: an I-Q sample region and a signal-to-noise ratio (SNR) of the received RF signal,wherein the processing circuitry is configured to determine whether or not to retransmit the received RF signal:when the I and Q samples of the received RF signal fall within the I-Q sample region, andwhen the SNR of the received RF signal is within a predetermined SNR range.