Abstract
Decrease of the pilot overhead is an important issue in vehicle-to-vehicle (V2V) underlay wideband massive multiple-input multiple-output (mMIMO) communication. To reduce the pilot overhead for channel acquisition, we propose phase shift adjustable pilots (PSAPs) for V2V underlay wideband mMIMO systems employing orthogonal frequency division multiplexing (OFDM). Motivated by the sparse property of the angle-delay (AD) domain channels in mMIMO, we first investigate channel acquisition for V2V underlay mMIMO-OFDM with PSAPs, and derive the optimal conditions to achieve the sum mean square error (sMSE) minimums of channel estimation and channel prediction, respectively. The optimal conditions indicate that the minimum sMSE can be achieved when the AD domain channel power spectra of cellular users (CUs) and transmitters in V2V communication pairs are non-overlapping after appropriate allocation of the available pilot phase shifts. Then an AD domain channel power spectrum based pilot allocation (ADCPS-PA)algorithm is developed according to the optimal conditions. Simulation results indicate that the achievable spectral efficiency for both cellular and V2V links can be significantly improved with PSAPs compared with that obtained by the conventional phase shift orthogonal pilot approach.
Highlights
With the arrival of 5G wireless communication, vehicleto-vehicle (V2V) communication has gained significant research interest for its potential in intelligent automotive and transportation industries
The optimal conditions indicate that the minimum sum mean square error (sMSE) can be achieved when the AD domain channel power spectra (CPS) of different cellular users (CUs) and transmitters in V2V communication pairs become non-overlapping with proper pilot phase shift allocation
The physical explanation of Propsition 1 is that the PI among users can be eliminated when the non-overlapping property for the equivalent AD domain channel power spectra of different CUs and VTxs are satisfied after proper pilot phase shift allocation, and the optimal sMSE performance can be achieved
Summary
With the arrival of 5G wireless communication, vehicleto-vehicle (V2V) communication has gained significant research interest for its potential in intelligent automotive and transportation industries. Author et al.: Preparation of Papers for IEEE TRANSACTIONS and JOURNALS acquire channel state information (CSI), the channel response is estimated in the delay domain and the phase shifts of pilots for different transmit antennas need to satisfy the orthogonality condition [6]. Based on the angle-delay (AD) domain channel sparsity [8], we first investigate channel acquisition for V2V underlay mMIMO-OFDM with PSAPs, and derive the optimal conditions under which the sum mean square error (sMSE) for channel estimation (CE) and channel prediction (CP) can be minimized, respectively. The optimal conditions indicate that the minimum sMSE can be achieved when the AD domain channel power spectra (CPS) of different CUs and transmitters in V2V communication pairs become non-overlapping with proper pilot phase shift allocation. Notations and acronyms used throughout this paper and their explanations are detailed in Table 1 and Table 2, respectively
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