335 research outputs found
Integrated Sensing and Communications with Joint Beam Squint and Beam Split for Massive MIMO
Integrated sensing and communications (ISAC) has attracted tremendous
attention for the future 6G wireless communication systems. To improve the
transmission rates and sensing accuracy, massive multi-input multi-output
(MIMO) technique is leveraged with large transmission bandwidth. However, the
growing size of transmission bandwidth and antenna array results in the beam
squint effect, which hampers the communications. Moreover, the time overhead of
the traditional sensing algorithm is prohibitive for practical systems. In this
paper, instead of alleviating the wideband beam squint effect, we take
advantage of joint beam squint and beam split effect and propose a novel user
directions sensing method integrated with massive MIMO orthogonal frequency
division multiplexing (OFDM) systems. Specifically, with the beam squint
effect, the BS utilizes the true-time-delay (TTD) lines to steer the beams of
different OFDM subcarriers towards different directions simultaneously. The
users feedback the subcarrier frequency with the maximum array gain to the BS.
Then, the BS calculates the direction based on the subcarrier frequency
feedback. Futhermore, the beam split effect introduced by enlarging the
inter-antenna spacing is exploited to expand the sensing range. The proposed
sensing method operates over frequency-domain, and the intended sensing range
is covered by all the subcarriers simultaneously, which reduces the time
overhead of the conventional sensing significantly. Simulation results have
demonstrated the effectiveness as well as the superior performance of the
proposed ISAC scheme.Comment: 13 pages, 11 figures, submitted to IEEE journa
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