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©A method for joint transmit-antenna to user association and scheduling in downlink single-user multiple-input multiple-output systems.

IP.com Disclosure Number: IPCOM000179760D
Publication Date: 2009-Feb-25

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention discloses a method for enabling communication between multiple transmitting antennas and multiple users (multiple user receive-antennas) in the downlink communication. The transmitting system can be a system of multiple co-located antennas, or it can be a Distributed Antenna System (DAS) where different subsets of antennas are geographically distributed but work together. In the invention the association between different user-data, the transmit-antennas to transmit each user-data, and the receive-antennas (or users) is flexible and determined by the invention through a joint consideration over many antenna to user assignments. The invention may also additionally determine which users to serve, and which antennas to power on.

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DoCoMo Communications Laboratories USA, Inc.

3240 Hillview Avenue, Palo Alto, CA 94304, USA

1 TITLE OF THE INVENTION

A method for joint transmit-antenna to user association and scheduling in downlink single-user multiple-input multiple-output systems.

2 INVENTOR(S)

Sean A. Ramprashad

Christine Pépin
Haralabos Papadopoulos
Carl-Erik W. Sundberg

3 FIELD OF THE INVENTION

The present invention relates to Single-User Multiple-Input Multiple-Output (SU-MIMO) wireless systems since each of the scheduled transmissions can be thought of as a SU-MIMO transmission in the presence of scheduled (selected) interference. More particularly, it relates to downlink communication in a Distributed Antenna Systems (DAS) wherein the associations of transmit- antennas to user terminals (or user receive-antennas) is flexible. Furthermore, since the invention schedules multiple concurrent SU-MIMO transmissions, specifying a joint association across all transmit-antennas, users, and user receive-antennas, the invention also relates to Multi-User MIMO (MU-MIMO) and/or Network MIMO (NW-MIMO) systems.

4 SUMMARY OF THE INVENTION

The invention discloses a method for enabling communication between multiple transmitting antennas and multiple users (multiple user receive-antennas) in the downlink communication. The transmitting system can be a system of multiple co-located antennas, or it can be a Distributed Antenna System (DAS) where different subsets of antennas are geographically distributed but work together. In the invention the association between different user-data, the transmit-antennas to transmit each user-data, and the receive-antennas (or users) is flexible and determined by the invention through a joint consideration over many antenna to user assignments. The invention may also additionally determine which users to serve, and which antennas to power on.

In the case of a DAS, the system consists of several transmit antennas that are spread geographically over a service area. In terms of the system architecture behind the DAS, the

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DoCoMo Communications Laboratories USA, Inc.

3240 Hillview Avenue, Palo Alto, CA 94304, USA

antennas can either be located at two or more base-stations, or may simply be remote antennas spread over an area and connected (e.g. via fiber) to centralized processing units. See Figure 1 to Figure 4 for various examples. A co-located system would simply have all antennas at one geographic location.

The invention is concerned with the allocation of transmission resources, e.g. time-frequency slots in an OFDM system or codes in a CDMA system, on each transmit-antenna to the users. In particular it allocates a given resource on each transmit-antenna to a single user, or to a single portion of user-data. One can consider this "user-data" as a uni...