Beamspace MU-MIMO for high-density gigabit small cell access at millimeter-wave frequencies

Abstract

Through orders-of-magnitude larger bandwidths and small wavelengths that enable high-dimensional multipleinput multiple-output (MIMO) operation, millimeter-wave (mmwave) systems operating from 30-300 GHz provide a unique opportunity for meeting the exploding capacity demands on wireless networks. Previously, the performance of multiuser MIMO (MU- MIMO) precoders that exploit the concept of beamspace MIMO (B-MIMO) communication -multiplexing data onto orthogonal spatial beams -was explored for access points (APs) equipped with n-dimensional uniform linear arrays (ULAs). It was shown that APs using reduced complexity B-MIMO transceivers achieve near-optimal performance with complexity that tracks the number of mobile stations (MSs). In this paper we explore the application of the reduced complexity B-MIMO transceivers to APs equipped with uniform planar arrays (UPAs) serving small cells. First, we apply B-MIMO theory to develop a frameworkfor analyzing the small cell in terms of the orthogonal beam footprints. We then examine the effect of several parameters on the system performance and demonstrate that the low-complexity transceivers enable 1000s of Gigabit/s aggregate rates in mmwave small cells serving hundreds of MSs.

5G Position and Orientation Estimation through Millimeter Wave MIMO

“…Since ∂a Tx,F /∂θ Tx = F H D Tx a Tx and ∂a Rx /∂θ Rx = D Rx a Rx , applying the Parseval's identity leads to (14). The term Φ(θ Tx , h) can be obtained by taking the derivatives with respect to real and imaginary parts of the channel coefficients and θ Tx and using the Parseval's identity as…”

Beam selection for performance-complexity optimization in high-dimensional MIMO systems

“…The 2D steering vector can be written as [8] a (e az e el ) = a (e az ) (>9 a (e el ) n , naz ne t where (>9 is the Kronecker product, e az and e el represent the azimuth and elevation spatial frequencies, corresponding to ¢ az and ¢ el with -7r /2 ::; ¢ az ::; 7r /2 and 0 ::; ¢ el ::; 7r /2. The channel matrix H is an n x K matrix, with the array indices arranged in Kronecker order.…”

“…The statistics of Wb = U� ware equivalent to the statistics of W because U n is unitary. For a 2D UPA, the beamforming matrix is given by Un = Un az (>9 Un el [8].…”

“…We build on previous work on hybrid analog-digital transceiver architectures exploiting the concept of beamspace MIMO (B-MIMO) conununication -multiplexing data onto orthogonal spatial beams -for near-optimal performance with reduced transceiver complexity [4], [5], [7], [8] . In order to take advantage of the performance-complexity optimization afforded by B-MIMO, it is first necessary to determine the optimal subset of orthogonal beams, which we term beam selection (BS).…”

Joint Design of Beam Selection and Precoding Matrices for mmWave MU-MIMO Systems Relying on Lens Antenna Arrays

“…Furthermore, the phase shifters needed in the hybrid structure are replaced by a switching network, which decreases the cost and complexity of the RF hardware as well as improving the power budget. In [20], beamspace MIMO is studied under multi-path propagation conditions, while its extensions to multiuser scenarios are considered in [21], [22]. Within this context, a critical problem of mmWave lens array systems is the design of effective beam selection and digital precoding schemes.…”