Realizing joint radar-communications in coherent MIMO radars

Abstract

The increasing interest on spectrum resources causes various efforts on developing smart and compact solutions as joint radarcommunication (JRC) systems. A JRC system can offer cost-effective solution with concurrent operation, as target sensing via radar processing and establishing communication links. JRC capability has been proposed over the years for different types of MIMO radars. However, a JRC capable monostatic coherent MIMO radar system is yet to be developed. These radars offer several advantages as fully coherent signal processing and coherent transmit beamforming which provides beampatterns to minimize probability of intercept. In this paper, two new waveform generation techniques suitable for JRC operation without disturbing transmit beamforming requirements and waveform orthogonality condition in space and time domain are proposed for monostatic coherent MIMO radars. Then, new communication methods are introduced for phase coded monostatic coherent MIMO radars. First method uses chirp-wise information encoding inside the radar pulse as intra-pulse communications. Second rotates the phase of a specific waveform on radiated symbols to a specific direction and the last method applies a small amount of progressive phase shift to the radar waveforms emitted from the antennas to create relative phase modulation between selected radar waveforms. Then, the performance of the proposed communication techniques are investigated in terms of bit error rate (BER) and generated waveforms are examined according to the orthogonality and transmit beamforming requirements.

Capacity analysis for joint radar-communication capable coherent MIMO radars

“…whereŝ null r (t; l) is the channel input when null direction fixed waveform generation method in [2] is used and A l = |G 1 (θ c )| is defined as amplitude of the radiated signal towards communication direction θ c . Although null direction fixed method introduces unintentional modulation, a phase correction procedure is proposed to fix the phase toward receiver.…”

“…Last communication method utilizes the progressive phase difference between orthogonal waveforms radiated from the first and the last antenna element caused by a small degrees of steering on transmit beampattern. Specifically, null direction fixed waveform generation method in [2] produces unintentional modulation, shown in Fig.1, on transmit signal towards the communication direction. This modulation affects the communication performance by its nature due to possible fades on signal amplitude through the radar pulse.…”

“…Communication capacity is evaluated for each channel condition. The results reveal that, using the single-side limited null direction fixed waveform generation method displays the best capacity performance under all channel conditions.Recently, a JRC-capable monostatic coherent MIMO radar system have been proposed in [2]. Coherent MIMO radars offer fully coherent signal processing and coherent transmit beamforming which present radiation patterns to reduce the probability of intercept.…”

“…JRC ability is accomplished for coherent MIMO radar without disturbing the orthogonality and transmit beamforming requirements. Three different novel communication methods are proposed in [2]. First method uses each sub-pulse in the radar pulse for communication.…”

LPI performance optimisation strategy for a JRCS

“…Recently, the joint radar‐communications system (JRCS), which can simultaneously estimate environment parameters from the radar returns and decode the received communications signals, has received remarkable attention and has been on a path from theory to practical deployment [7–11]. In [12], Paul et al present a survey of RF sensing and communications convergence research, which can be seen as a point of departure.…”