• Mohammed Fahad
• Abdul Rafay Akber
• Ahsan
• Dr. Abdul Mateen Ahmed

In this paper, we propose a multipath extraction-based uplink/downlink channel estimation scheme for wideband massive multiple-input multiple-output (MIMO) systems, where orthogonal frequency division multiplexing (OFDM) is adopted and the beam squint effect is considered. Firstly, we investigate the spatial- and frequency-wideband effects and obtain the relationship between angle-delay information and coordinates of on-grid paths. Secondly, according to the spatial- and frequency-wideband effects, we design a pilot pattern in uplink training to ensure that exact paths can be acquired from limited potential paths. Combined with pilot pattern design, a modified density-based spatial clustering of applications with noise (M-DBSCAN) approach is proposed to acquire the on-grid potential paths. Potential paths are used for initialization in uplink channel extraction. Due to the fact that coordinates of only a few potential paths are close to those of true paths, the uplink multipath extraction problem can be regarded as an off-grid sparse signal reconstruction problem. To deal with this issue, an off-grid sparsity adaptive matching pursuit (OSAMP) based compressive sensing method with low computational complexity is proposed. With the aid of antenna array theory and array signal processing, we build a spatial basis expansion model (SBEM) to represent the UL/DL channels with much fewer parameter dimensions. Hence, both UL and DL channel estimation of multiusers can be carried out with a small amount of training resource, which significantly reduces the training overhead and feedback cost. Simulation results are provided to demonstrate the effectiveness of our proposed low computational complexity channel estimation method.

massive MIMO, OFDM, 5G, Channel Estimates.

"Bitwise Channel Estimation for UL/DL For Massive MIMO", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.9, Issue 5, page no.b784-b792, May-2022, Available :http://www.jetir.org/papers/JETIR2205206.pdf

"Bitwise Channel Estimation for UL/DL For Massive MIMO", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.9, Issue 5, page no. ppb784-b792, May-2022, Available at : http://www.jetir.org/papers/JETIR2205206.pdf