# US 10,320,455 B2 · Systems and methods to coordinate transmissions in distributed wireless systems via user clustering

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- Number: US 10,320,455 B2
- Document ID: US10320455B2
- Status: Granted
- Kind: B2
- Application number: 15/181,383
- Filed: 2016-06-13
- Published: 2016-10-06
- Granted: 2019-06-11
- Earliest claimed: 2004-04-02
- Assignees: Rearden, LLC
- Applicants: Rearden, LLC
- Inventors: Antonio Forenza; Erik Lindskog; Stephen G. Perlman
- Web page: https://patentgrep.com/patent/US10320455B2

## CPC

- H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B 7/022: Site diversity; Macro-diversity (using two or more spaced independent antennas H04B7/04)
- H04B 7/024: Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
- H04B 7/0434: {using multiple eigenmodes}
- H04B 7/046: {taking physical layer constraints into account}
- H04B 7/0469: {taking special antenna structures, e.g. cross polarized antennas into account}
- H04B 7/0626: {Channel coefficients, e.g. channel state information [CSI]}
- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04L 25/0232: {by interpolation between sounding signals}
- H04W 24/02: Arrangements for optimising operational condition
- H04W 24/08: Testing, {supervising or monitoring} using real traffic
- H04B 7/0452: Multi-user MIMO systems
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Systems and methods are described for coordinating transmissions in distributed wireless systems via user clustering. For example, a method according to one embodiment of the invention comprises: measuring link quality between a target user and a plurality of distributed-input distributed-output (DIDO) distributed antennas of base transceiver stations (BTSs); using the link quality measurements to define a user cluster; measuring channel state information (CSI) between each user and each DIDO antenna within a defined user cluster; and precoding data transmissions between each DIDO antenna and each user within the user cluster based on the measured CSI.

## Claims

### Claim 1

A multiuser (MU) multiple antenna system (MAS) comprising:
one or a plurality of centralized units communicatively coupled to a plurality of distributed transceiver stations or antennas via a network;
the network consisting of wireline or wireless links or a combination of both, employed as a backhaul communication channel;
a plurality of users communicatively coupled to the plurality of distributed transceiver stations via a plurality of wireless links;
the centralized units adaptively selecting a plurality of subsets of transceiver stations based on the quality of the wireless links between the transceiver stations and the user, wherein every subset of transceiver stations is associated to one of the plurality of users.

### Claim 2 (depends on 1)

The system as in claim 1 wherein every subset of transceiver stations employs precoding to send (or receive) one or a plurality of concurrent non-interfering data streams to (or from) the users over the wireless links.

### Claim 3 (depends on 1)

The system as in claim 1 wherein the quality of the wireless links is estimated based on channel characterization data between the distributed transceiver station and the users.

### Claim 4 (depends on 1)

The system as in claim 1 wherein one or multiple subsets of transceiver stations are dynamically recomputed as one or multiple users move.

### Claim 5 (depends on 4)

The system as in claim 4 wherein radio frequency (RF) power transmitted over the wireless links is adjusted to maintain the number of transceiver stations within each subset below a predefined value.

### Claim 6

A multiuser (MU) multiple antenna system (MAS) comprising:
a plurality of users communicatively coupled to a plurality of distributed transceiver stations via a plurality of wireless links;
one or a plurality of centralized units computing a matrix containing the channel state information (CSI) of the wireless links;
the centralized units dynamically selecting one or a plurality of sub-matrices within the matrix and computing precoding weights for the users from each of the sub-matrices.

### Claim 7 (depends on 6)

The system as in claim 6 wherein the sub-matrices are selected based on a link-quality metric determining the quality of the wireless links.

### Claim 8 (depends on 6)

The system as in claim 6 wherein the sub-matrices are dynamically recomputed as one or multiple users change their positions in space.

### Claim 9 (depends on 6)

The system as in claim 6 wherein the precoding weights are computed to create points of zero RF energy to one or multiple users.