A Superimposed Pilot-Based Integrated Radar and Communication System

Abstract

In this paper, a multiple-input multiple-output (MIMO) integrated radar and communication system based on orthogonal frequency division multiplexing (OFDM) signals is proposed. We consider a bistatic scenario. Exploiting superimposed pilots and orthogonal space-time block code (OSTBC) precoding, transmitted power can be effectively used in both information symbol sending and target sensing with little energy waste and performance degradation. The expectation maximization (EM) is employed to estimate unknown symbols and the channel jointly, which can take the place of matched filtering in traditional radar. In the EM algorithm, we propose to calculate the channel expectation by using Gaussian distribution of the symbol estimation, which can make full use of the OSTBC property of sensing spatial diversity with fast maximum likelihood decoding. The autocorrelation response, and the Doppler response of moving targets in slow time are verified by numerical experiments. Simulations also show superimposed pilot is suitable in the integrated radar and communication system, even when targets with large Doppler shift exist. INDEX TERMS Integrated radar and communication, OFDM, MIMO, superimposed pilot, OSTBC.

On SFBC Schemes for Enabling Virtual Array Concept in Monostatic ISAC Scenarios

“…However, it lacks the estimation of the Doppler shift. More recently, [16] proposed an estimation method based on matched filters (MF) for a bistatic ISAC system. Here, the authors used pilots and correlation for a MIMO OFDM ISAC system.…”

“…The radar signal processing exploits the knowledge of the orthogonal SFBC code and the transmitted symbols to estimate the direction, delay and Doppler through the received echo from targets. The proposed method exploits the full OFDM frame for delay/Doppler processing, which is different to the work in [16]. Besides, since the Doppler shift and data are first eliminated, the estimate is free of ambiguities and the complexity is considerably reduced compared to correlation approaches [5,17].…”

Joint range and velocity estimation for orthogonal frequency division multiplexing‐based high‐speed integrated radar and communications system

“…There, T is the time width of an OFDM symbol; T cp is the time width of the cyclic prefix (CP); and $${T_{\rm{s}}} = {T_{{\rm{cp}}}}\; + T$$ is the time width of a complete OFDM symbol. To avoid inter‐symbol interference (ISI), T cp is required to be greater than the maximum delay of multi‐path effect [24], where $${T_{{\rm{cp}}}} = \;gT$$ and g is the CP coefficient. Also, $${N_{\rm{s}}}{T_{\rm{s}}}$$ is the duration of a pulse; N s is the number of symbols contained in a pulse; and, T p is the pulse repetition interval.…”

5G PRS-Based Sensing: A Sensing Reference Signal Approach for Joint Sensing and Communication System

“…Pilot based JSC waveform design was mainly studied from the perspectives of pilot sequence selection [14,15], pilot insertion mode [13,16,17], and time-frequency resource allocation [12,13,18]. In terms of pilot sequence selection, Kumari et al [14] applied the preamble signal of the 802.11ad in radar sensing due to its good auto-correlation property.…”