Index modulation for OFDM RadCom systems

Abstract

This paper studies a novel Radar and wireless communication fusion system namely, Rad-Com, using orthogonal frequency division multiplexing index modulation waveforms. From the communication perspective, information is conveyed not only through modulated orthogonal frequency division multiplexing subcarriers but also by the active subcarrier indices that are dynamically updated at the transmitted symbol rates. When compared with conventional orthogonal frequency division multiplexing communication systems, only a subset of subcarriers is activated in the proposed orthogonal frequency division multiplexing index modulation system, which reduces signal peak-to-average ratios, leading to enhanced power amplifier efficiency. From the Radar sensing perspective, the Radar range-velocity profile obtained using compressed sensing approach is simulated and presented. It is shown that orthogonal frequency division multiplexing index modulation Rad-Com system can enhance the transmission data rates when low-order modulation schemes are adopted e.g. binary phase shift keying, and maintain similar Radar performance compared with the orthogonal frequency division multiplexing counterpart when the system is carefully designed. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

An Experimental Study of Radar-Centric Transmission for Integrated Sensing and Communications

“…In comparison with previous radar-centric DFRC studies [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], this study presents a reduced hardware complexity method such that it does not need multiple antennas and multiple analog and digital processing chains. It only needs a dual-polarized antenna and one or two analog or digital processing chains.…”

“…Since IM does not require special waveform types and can be performed without significantly changing the signals, IM has been recently considered to transmit data within radar waveforms [20], [21], [22], [23], [24], [25], [26], [27], [28], [29]. One of the first attempts to utilize radar waveform features as indexes to deliver data was in [20], where the radar system selects the antennas out of all antenna elements available in the array and assigns orthogonal radar waveforms to them in order to embed data into radar pulses, achieving megabits per second data rates while performing radar sensing as the primary function.…”

“…For instance, the communication data may be embedded into radar waveforms in an FH-MIMO radar system using various signaling strategies such as antenna selection, quadrature amplitude modulation (QAM), PSK modulation or carrier frequency selection [29]. On the other hand, OFDM waveforms were also considered with IM such as in [26], where authors proposed a DFRC scheme that conveys data by selecting the subcarrier indexes of the OFDM signals in addition to the data conveyed through the OFDM signals themselves while also performing radar sensing.…”

IM-OFDM ISAC Outperforms OFDM ISAC by Combining Multiple Sensing Observations

“…A method is to use compressed sensing as in [31], where the transmitted signal is a typical IM-OFDM signal. A compressed sensing problem is formulated based on the received signal, in an attempt to interpolate the missing information.…”

Radar-Centric ISAC Through Index Modulation: Over-the-air Experimentation and Trade-offs

“…For example, selections of antennas, subcarriers, time slots or other signal features can be exploited as indexes [6]. IM does not require special waveform types and may be implemented without significantly changing the signals, hence it has been recently considered to modulate communication data within radar waveforms [7]- [13]. For instance, Huang et.…”