Opportunistic beamforming and scheduling of users in a communication system

• US 7,760,685 B2
• Filed: 02/09/2007
• Issued: 07/20/2010
• Est. Priority Date: 11/26/2003
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Avidor, Dan, Ling, Jonathan, Papadias, Constantinos B.
• Primary Examiner(s): Nguyen; David Q
• Application Number:
  US11/704,326
• Publication Number:
  US 20070135139A1
• Time in Patent Office: 1,257 Days
• Field of Search: 455/453, 455/525, 455/63.2, 455/450, 455/62
• US Class Current: 370/328
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 72/046 the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

In a method of improving system throughput while reducing packet delay for users of a wireless communication system, a user may be selected from a user population based on a parameter that is tracked for each user of the user population. A preferred beam for the user may be determined based on a highest running average data rate from each beam of a finite plurality of selectable beams so as to maximize the selected user'"'"'s chances to be scheduled to receive the next packet. The preferred beam may be used for transmitting a pilot signal for scheduling a user in the user population to receive a next transmission on the preferred beam.

Claims

1. A method of scheduling a user for receiving a transmission, comprising:

selecting, at a network element, a user from a user population based on a parameter that is tracked for each user in the user population;

determining, at a network element, for a given timeslot, a running average data rate for each beam of a finite plurality of selectable beams based on past reports that, for each beam, have been previously received from the selected user;

selecting, at a network element, a beam having the highest running average data rate as a preferred beam for the selected user;

transmitting, at a network element, a pilot signal to the user population using the preferred beam;

receiving, at a network element, reports from each user in the user population in response to the pilot signal transmitted using the preferred beam; and

scheduling, at a network element, a user in the user population to receive a next transmission on the preferred beam, based on the reports received.

2. The method of claim 1, wherein the tracked parameter is:

a short term throughput for each user calculated using a filtering process that is dictated by a given application;

or

a short term throughput normalized by a long term throughput for each user, the short term throughput calculated based on a given application.

3. The method of claim 1, wherein the step of scheduling further includes:

receiving feedback from each user of the user population in response to the pilot signal, the feedback including information related to a maximum supportable data rate for the user; and

running a scheduling algorithm to prioritize the user population for receiving a next transmission in a current timeslot on the preferred beam,

wherein the selected user has been moved up in priority to receive the next transmission based on its feedback.

4. The method of claim 1, wherein:

the tracked parameter is a waiting time for each user that represents a duration of time since the user has received its last packet; and

the selected user is the longest waiting user.

5. The method of claim 1, wherein selecting the preferred beam is designed to enhance the selected user'"'"'s priority to receive the next transmission based on maximum supportable data rate information contained in the selected user'"'"'s feedback.

6. A method of improving system throughput while reducing packet delay for users of a wireless communication system, comprising:

selecting, at a network element, a user from a user population based on a parameter that is tracked for each user of the user population; and

determining, at a network element, a preferred beam for the user based on a highest running average data rate from each beam of a finite plurality of selectable beams so as to maximize the selected user'"'"'s chances to be scheduled to receive the next packet, the preferred beam used for transmitting a pilot signal for scheduling a user in the user population to receive a next transmission on the preferred beam.

7. The method of claim 6, wherein

the tracked parameter is a waiting time for each user that represents a duration of time since the user has received its last packet, and

the selected user is the user having the longest waiting time.

8. The method of claim 6, wherein:

the tracked parameter is a short term throughput normalized by a long term throughput for each user and calculated as a ratio of the short term throughput to the long term throughput; and

the selected user is the user having the lowest ratio.

9. The method of claim 6, wherein determining the preferred beam includes, for a given timeslot:

determining a running average data rate for each beam of the finite plurality of selectable beams based on past reports that, for each beam, have been previously received from the selected user, and

selecting a beam having the highest running average data rate as the preferred beam.