Two-stage estimation algorithm based on interleaved OFDM for a cooperative bistatic ISAC scenario

This paper considers a cooperative bistatic scenario for integrated sensing and communication (ISAC) paradigm, where transmitter and receiver base stations (BS) are connected through the front-haul to a central unit (CU), enabling cooperation. A multiple-input multiple-output (MIMO) configuration is considered in combination with orthogonal frequency division multiplexing (OFDM). The communication and radio-sensing functions are performed in orthogonal sets of sub-carriers, where the sub-carriers allocated to radio-sensing are distributed among antennas in an interleaved way. The interleaved frame structure is exploited in the design of a new parameter estimation method. The proposed method is a two-stage algorithm to estimate the delay/Doppler shift and angular position of objects (paths) in the channel. First, the multiple signal classification (MUSIC) algorithm estimates the angle-of-arrival (AoA) of the paths. Then, the delay, Doppler shift and angle-of-departure (AoD) are jointly estimated for each AoA combining an extended search over the AoD domain and a two-dimensional periodogram. The simulations show that the delay, Doppler shift and AoA are estimated correctly, while the estimation of the AoD may report error, although it can be compensated.