Spatial-wideband compensation in wideband massive MIMO systems
This invention provides a novel transceiver design to control/compensate for the spatial-wideband effect in wideband massive multiple-input multiple-output (MIMO) systems for both sensing and communication networks. The proposed design aims to divide the ultra-wideband signal into narrow band beams and control them with a simplified exhaustive search-based precoding to align the beam angle to the target direction.
1 . A transceiver for use in massive MIMO systems for sensing and/or communication networks wherein; said transceiver comprises a conventional LAS design for a massive MIMO system where NL phase shifters (PSs) connect to L subband analog filters for each phase shifter (PS) and a multiple pole multiple throw (MPMT) switching network to connect the output of the L filters to L out of P antenna elements in each lens instead of using SPMT switching in the conventional LAS design.
2 . A method to build and control a transceiver using the following steps:
designing a conventional LAS massive MIMO system;
adding L analog subband filters to each lens after the phase shifter component to divide the ultra-wideband signal into chunks of narrowband signals;
replacing an SPMT switching network in the conventional LAS design with a MPMT switching network to connect the output of the L analog subband filters to L out of P antenna elements on each lens;
providing a conventional exhaustive search for a precoding design to control a proposed transceiver design; and
adding a certain linear threshold is to the exhaustive search to perform faster and to reduce a complexity overhead of the conventional exhaustive search on the precoding design and present a simplified exhaustive search-based precoder.
3 . The method of claim 2 , wherein the step for dividing ultra-wideband signals into chunks of narrowband signals comprises the steps of;
assuming that the number of antenna elements under each lens P should be equal to or larger than a number of subgroups (P≥L) to increase an angular resolution of each lens;
using a frequency dependent analog precoder given as;
F
=
F
LAS
′
(
k
′
)
F
PS
,
where F′ LAS is the selection matrix for the proposed LAS design, k′=1, 2, . . . , L;
activating multiple antenna elements within one column in the 5 matrix, wherein the s t (i) activating element is;
s
t
(
i
)
(
p
)
=
{
1
,
min
p
(
❘
"\[LeftBracketingBar]"
Δϕ
❘
"\[RightBracketingBar]"
)
0
,
otherwise
,
where Δø is a main lobe angle difference between an ideal beam and a squinting beam; and
applying a simplified s t (i) exhaustive search to reduce the complexity overhead where a specific threshold is put to stop the search when the Δø is less or equal to the threshold, herein the condition of activating the elements in is given as
❘
"\[LeftBracketingBar]"
Δϕ
❘
"\[RightBracketingBar]"
≤
ζ
(
k
′
)
where ζ(k′) is the threshold which is a function of subband filter indices.