Multiple spatial data streams via a re-configurable reflective device
A method of operating a re-configurable reflective device, RRD ( 109 ) is provided. One or more wireless communication devices ( 102, 103, 104 ) are served by an access node ( 101 ) via the RRD ( 109 ) using multiple spatial data streams. The RRD ( 109 ) comprises multiple reflective elements ( 1094 ), the multiple reflective elements ( 1094 ) being grouped into a plurality of subsets ( 691 - 697 ), the multiple reflective elements ( 1094 ) of each subset ( 691 - 697 ) being re-configurable to provide multiple spatial filters. The method comprises obtaining, from the access node ( 101 ) and for each subset ( 691 - 697 ) of the plurality of subsets ( 691 - 697 ), a respective first indicator indicative of a respective entry of a respective first codebook and a respective second indicator indicative of a respective entry of a respective second codebook, and reconfiguring, for each subset ( 691 - 697 ) of the plurality of subsets ( 691 - 697 ), the respective multiple reflective elements ( 1094 ) to provide a respective one of the multiple spatial filters, based on the respective entry of the respective first codebook and the respective entry of the respective second codebook.
1 . A method of operating a re-configurable reflective device (RD) wherein one or more wireless communication devices are served by an access node via the RD using multiple spatial data streams, wherein the RD comprises multiple reflective elements, the multiple reflective elements being grouped into a plurality of subsets, the multiple reflective elements of each subset being re-configurable to provide multiple spatial filters, wherein the method comprises:
obtaining, from the access node and for each subset of the plurality of subsets, a respective first indicator indicative of a respective entry of a respective first codebook and a respective second indicator indicative of a respective entry of a respective second codebook, and
re-configuring, for each subset of the plurality of subsets, the respective multiple reflective elements to provide a respective one of the multiple spatial filters, based on the respective entry of the respective first codebook and the respective entry of the respective second codebook.
2 . The method of claim 1 , further comprising:
in a calibration phase, participating in a channel sounding procedure between the access node and the RD to sound a plurality of channels between the access node and each one of the plurality of subsets, and obtaining, from the access node upon participating in the channel sounding procedure and for each one of the multiple subsets, the respective second codebook.
3 . The method of claim 2 , wherein the first codebooks are predefined and remain fixed throughout the channel sounding procedure.
4 . A method of operating an access node, the access node serving one or more wireless communication devices via a re-configurable device (RRD) using multiple spatial data streams, wherein the RD comprises multiple reflective elements, the multiple reflective elements being grouped into a plurality of subsets, the multiple reflective elements of each subset being re-configurable to provide multiple spatial filters, wherein the method comprises:
providing, to the RD and for each subset of the plurality of subsets, a respective first indicator indicative of a respective entry of a respective first codebook and a respective second indicator indicative of a respective entry of a respective second codebook.
5 . The method of claim 4 , further comprising:
in a calibration phase, participating in a channel sounding procedure between the access node and the RD to sound a plurality of channels between the access node and each one of the plurality of subsets,
determining the second codebooks based on the plurality of channels, and
providing the second codebooks to the RD.
6 . The method of claim 5 , wherein said determining of the second codebooks comprises an optimization, wherein a goal function of the optimization penalizes differences between elements of a matrix obtained from multiplying a precoder matrix defining precoding at the access node with a channel matrix associated with each one of the subsets and optionally maximize a gain at the RD.
7 . The method of claim 4 , further comprising:
for each one of the one or more wireless communication devices, allocating one or more subsets of the plurality of subsets to at least one spatial data stream of the multiple spatial data streams associated with the respective wireless communication devices.
8 . The method of claim 7 , wherein said allocating is based on at least one of a count of the one or more wireless communication devices, a count of the multiple subsets, or rate requirements associated with each one of one or more wireless communication devices.
9 . The method of claim 4 , wherein the entries of the first codebook define reflection directions at the RD towards the one or more wireless communication devices.
10 . The method of claim 4 , wherein the entries of the second codebook define a selection from the multiple spatial data streams at the RD.
11 . The method of claim 9 , wherein the first indicator for a first subset of the multiple subsets defines a first reflection direction towards a first one of the one or more wireless communication devices, wherein the second indicator for the first subset of the multiple subsets defines the selection of a first spatial data stream, wherein the first indicator for a second subset of the multiple subsets defines a second reflection direction towards the first one of the one or more wireless communication devices, wherein the second indicator for the second subset of the multiple subsets defines the selection of a second spatial data stream different from the first spatial data stream.
12 . The method of claim 4 , wherein, at a first point in time, the first indicators and the second indicators of two or more of the plurality of subsets define different spatial filters of the multiple spatial filters.
13 . The method of claim 12 , wherein, at a second point in time different than the first point in time, the first indicators and the second indicators of two or more of the plurality of subsets define the same spatial filter of the multiple spatial filters.
14 . A re-configurable device (RRD), comprising multiple passive reflective elements being grouped into a plurality of subsets, wherein, for each subset of the plurality of subsets, the reflective elements the respective subset are arranged on a respective circle; and
wherein the reflective elements of each subset of the plurality of subsets are evenly spaced on the respective circle.
15 . The RD of claim 14 , wherein the respective circles of the plurality of subsets are concentrically arranged.
16 . The RD of claim 14 , wherein all subsets include the same count of reflective elements.
17 . The RD of claim 14 , wherein the respective circles of at least two subsets of the plurality of subsets have different diameters.
18 . A communication system comprising the RD of claim 14 and an access node comprising multiple antenna elements arranged on a circle.