Shaping mmWave wireless channel via multi-beam design using reconfigurable intelligent surfaces

Patent metadata

Field	Value
Publication number	US-11909479-B2
Application number	US-202217863720-A
Country	US
Kind code	B2
Filing date	Jul 13, 2022
Priority date	Jul 14, 2021
Publication date	Feb 20, 2024
Grant date	Feb 20, 2024

Abstract

A method for shaping a mmWave wireless channel in a wireless network is presented. The method includes enabling communication between a multi-antenna transmitter and a multi-antenna receiver, positioning a reconfigurable intelligent surface (RIS) in a vicinity of the multi-antenna transmitter and the multi-antenna receiver, constructing the RIS as a uniform planar array (UPA) structure forming a multi-beamforming framework, a surface of the UPA defining an array of discrete elements arranged in a grid pattern, wherein parameters of the discrete elements of the UPA are controllable to achieve multiple disjoint beams covering different solid angles, and enabling the plurality of users of the plurality of mobile devices positioned in blind spots of a coverage map to communicate with the multi-antenna transmitter by employing the MS to generate sharp and effective beams having almost uniform gain in a desired angular coverage interval (ACI).

First claim

What is claimed is:

1. A method for shaping a millimeter wave (mmWave) wireless channel in a wireless network, the method comprising:
receiving signals at a reconfigurable intelligent surface (RIS) in a vicinity of a multi-antenna transmitter and a multi-antenna receiver the signals communicated between the multi-antenna transmitter and the multi-antenna receiver through the reconfigurable intelligent surface (RIS), the RIS being a uniform planar array (UPA) structure forming a multi-beamforming framework, a surface of the UPA defining an array of discrete elements arranged in a grid pattern, wherein parameters of the discrete elements of the UPA are controllable to achieve multiple disjoint beams covering different solid angles, the RIS reflecting the signals received from the multi-antenna transmitter toward the multi-antenna receiver; and
and enabling the plurality of users of the plurality of mobile devices positioned in blind spots of a coverage map to communicate with the multi-antenna transmitter by employing the RIS to generate sharp and effective beams having almost uniform gain in a desired angular coverage interval (ACI).

2. The method of claim 1 , wherein channel matrices of each discrete element of the UPA of the RIS are given as:
H t =d M t {Ω t }ρ t d M H {Ω 1 }, and

H r =d M {Ω 2 }ρ r d M r H {Ω r },

where Ω 1 , Ω 2 are solid angles of departure (AoD) of beams transmitted from the multi-antenna transmitter and the RIS, Ω 1 and Ω 2 are solid angles of arrival (AoA) of the beams received at the RIS and the multi-antenna receiver, respectively, a gain of the line-of-sight (LoS) paths from the transmitter to the RIS and from the RIS to the receiver are demoted by ρ 1 and ρ r respectively, and d M t , d M , d M H , and d M r H and denotes various directivity vectors defining distances between the discrete elements of ti UPA of the RIS.

3. The method of claim 1 , wherein a beamforming vector is defined as:

c
=

[

c

0
,
0

,
…

,

c

0
,

M

h
-
1

,

c

1
,
0

,
…

,

c

M

v
-
1

,

M

h
-
1

]

wherein values of phase shift θ k and attenuation value β k for the k th elements of the RIS are found by using corresponding beamforming coefficient c k and a value of the k th element of a directivity vector d M (Ω 1 ) for any receive incident solid an Ω 1 .

4. The method of claim 1 , wherein the sharp and effective beams depend on solid angles at which incident waves from the multi-antenna receiver activate the discrete elements of the UPA.

5. The method of claim 1 , wherein the RIS is a passive RIS where both phase control and gain control are permitted.

6. The method of claim 1 , wherein values for a phase shift and an attenuation value of the MS are determined by using corresponding beamforming coefficients and a value of a kth element of a directivity vector for any receive incident solid angle.

7. The method of claim 1 , wherein the multi-beamforming framework is designed as an optimization problem.

8. A non-transitory computer-readable storage medium comprising a computer-readable program for shaping a millimeter wave (mmWave) wireless channel in a wireless network, wherein the computer-readable program when executed on a computer causes the computer to perform the steps of:
receiving signals at a reconfigurable intelligent surface (RIS) in a vicinity of a multi-antenna transmitter and a multi-antenna receiver to communicate between the multi-antenna transmitter and the multi-antenna receiver through the reconfigurable intelligent surface (RIS), the RIS being a uniform planar array (UPA) structure forming a multi-beamforming framework, a surface of the UPA defining an array of discrete elements arranged in a grid pattern, wherein parameters of the discrete elements of the UPA are controllable to achieve multiple disjoint beams covering different solid angles, the RIS reflecting the signals received from the multi-antenna transmitter toward the multi-antenna receiver; and
enabling the plurality of users of the plurality of mobile devices positioned in blind spots of a coverage map to communicate with the multi-antenna transmitter by employing the RIS to generate sharp and effective beams having almost uniform gain in a desired angular coverage interval (ACI).

9. The non-transitory computer-readable storage medium of claim 8 , wherein channel matrices of each discrete element of the UPA of the RIS are given as:
H t =d M t {Ω t }ρ t d M H {Ω 1 }, and

H r =d M {Ω 2 }ρ r d M r H {Ω r },

where Ω 1 and Ω 2 are solid angles of departure (AoD) of beams transmitted from the multi-antenna transmitter and the RIS, Ω 1 and Ω r are solid angles of arrival (AoA) of the beams received at the RIS and the multi-antenna receiver, respectively, a gain of the line-of-sight (LOS) paths from the transmitter to the RIS and from the RIS to the receiver are denoted by ρ t and ρ r , respectively, and d M t , d M , D M H , and d M r H denotes various direct v ty vectors defining distances between the discrete elements of the UPA of the RIS.

10. The non-transitory computer-readable storage medium of claim 8 , wherein a beamforming vector is defined as:

c
=

[

c

0
,
0

,
…

,

c

0
,

M

h
-
1

,

Assignees

• Nec Lab America Inc
• Nec Corp

Inventors

• Khojastepour Mohammad
• Torkzaban Nariman

Classifications

• H04B7/0617 Primary

  for beam forming · CPC title

• H04B7/10

  Polarisation diversity; Directional diversity · CPC title

• H04B7/15507

  Relay station based processing for cell extension or control of coverage area, (network planning with network coordinated processing with regard to cell extension H04W16/26; network topologies using dedicated repeater stations H04W84/047; terminal devices adapted for relaying to or from an other terminal H04W88/04) · CPC title

• H04B7/15528

  Control of operation parameters of a relay station to exploit the physical medium · CPC title

• H04B7/04013

  Intelligent reflective surfaces · CPC title