A sub-band or multi-band coded OFDM radar apparatus , comprising: a set of antennas ; an analog circuit ; a digital circuit ; a medium access control (MAC) controller ; a processor operably connected to the set of antennas , the analog circuit , the digital circuit , and the MAC controller , the processor configured to: decompose wideband waveform signals into a time-frequency waveform based on a sequence of sub-band signals; generate a time-frequency radar waveform based on the decomposed wideband waveform signals; map, based on the time-frequency radar waveform, a constant amplitude zero auto-correlation (CAZAC) sequence into orthogonal frequency division multiplexing (OFDM) sub-carriers to generate a first radar signal; and a transceiver operably connected to the processor , the transceiver configured to: transmit, to a target object via a transmit antenna of the set of antennas , the first radar signal ; and receive, via a receive antenna of the set of antennas , a second signal that is reflected or backscattered from the target object; wherein the processor is further configured to: determine each of the sub-band signals based on the first radar signal and the second signal; obtain a third signal by processing each of the sub-band signals in a frequency domain; aggregate each of the sub-band signals based on the third signals; and generate a correlation output in a time domain based on each of the aggregated sub-band signals. a set of antennas ; an analog circuit ; a digital circuit ; a medium access control (MAC) controller ; a processor operably connected to the set of antennas , the analog circuit , the digital circuit , and the MAC controller , the processor configured to: decompose wideband waveform signals into a time-frequency waveform based on a sequence of sub-band signals; generate a time-frequency radar waveform based on the decomposed wideband waveform signals; map, based on the time-frequency radar waveform, a constant amplitude zero auto-correlation (CAZAC) sequence into orthogonal frequency division multiplexing (OFDM) sub-carriers to generate a first radar signal; and decompose wideband waveform signals into a time-frequency waveform based on a sequence of sub-band signals; generate a time-frequency radar waveform based on the decomposed wideband waveform signals; map, based on the time-frequency radar waveform, a constant amplitude zero auto-correlation (CAZAC) sequence into orthogonal frequency division multiplexing (OFDM) sub-carriers to generate a first radar signal; and a transceiver operably connected to the processor , the transceiver configured to: transmit, to a target object via a transmit antenna of the set of antennas , the first radar signal ; and receive, via a receive antenna of the set of antennas , a second signal that is reflected or backscattered from the target object; transmit, to a target object via a transmit antenna of the set of antennas , the first radar signal ; and receive, via a receive antenna of the set of antennas , a second signal that is reflected or backscattered from the target object; wherein the processor is further configured to: determine each of the sub-band signals based on the first radar signal and the second signal; obtain a third signal by processing each of the sub-band signals in a frequency domain; aggregate each of the sub-band signals based on the third signals; and generate a correlation output in a time domain based on each of the aggregated sub-band signals. determine each of the sub-band signals based on the first radar signal and the second signal; obtain a third signal by processing each of the sub-band signals in a frequency domain; aggregate each of the sub-band signals based on the third signals; and generate a correlation output in a time domain based on each of the aggregated sub-band signals. <EOS>