METHOD, APPARATUS AND COMPUTER PROGRAM FOR DOWNLINK MU-MIMO POWER SETTINGS AND CONTROL

• US 20090318183A1
• Filed: 06/23/2009
• Published: 12/24/2009
• Est. Priority Date: 06/23/2008
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Hugl, Klaus, Lindh, Lars E., Roman, Timo E.
• Granted Patent: US 8,326,341 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0041 Frequency-non-contiguous
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA

Abstract

A set of J predetermined power level offsets that scale transmission power per user are stored in a local computer-readable memory. A set of N users to which are allocated overlapping downlink frequency resources are selected. From the stored set is then selected a power level offset. An indication of the selected power level offset is signaled to at least one of the N users; and the at least one of the N users are also sent a multiplexed transmission using the selected power level offset. N is an integer at least equal to two, J is an integer at least equal to two, and at least one member of the set is other than 1/n in which n is any positive integer less than N_max in which N_max is a maximum number of users that can be multiplexed together. Various embodiments include an apparatus such as a network access node, a method, and a stored computer program. Also detailed are apparatus and method and stored computer program for practicing the invention from the perspective of the user/UE.

Claims

1. A method comprising:

storing in a local computer-readable memory a set of J predetermined power level offsets that scale transmission power per user;

selecting, by at least one processor, a set of N users to which are allocated overlapping downlink frequency resources;

selecting from the set, by the at least one processor, a power level offset;

signaling, via at least one transmitter, to at least one of the N users an indication of the selected power level offset; and

sending, via the at least one transmitter, a multiplexed transmission to the N users in which the transmission to the at least one of the N users is sent with the selected power level offset;

in which N is an integer at least equal to two, J is an integer at least equal to two, and at least one member of the set is other than 1/n in which n is any positive integer less than N_max in which N_max is a maximum number of users that can be multiplexed together.

2. The method according to claim 1, wherein selecting from the set the power level offset comprises:

determining a total number L of logical resources that are allocated to all of the selected N users across a subframe;

determining a unique number U of the frequency resources over which the total number of logical resources are distributed; and

wherein the selecting the power level offset from the stored set is based on a ratio U/L of the unique number of frequency resources to the total number of logical resources, in which U and L are each integers greater than two;

and wherein sending the multiplexed transmission is across all U of the unique frequency resources.

3. The method according to claim 1, in which the selected power level offset is selected to be nearest to but not exceeding 100% of maximum transmit power usage.

4. The method according to claim 1, wherein the frequency resources are allocated physical resource blocks within a subframe, and wherein the selected power level offset is signaled to all of the N users and the multiplexed transmission is sent to all of the N users with the selected power level offset.

5. The method according to claim 1, wherein sending the multiplexed transmission comprises sending a multi-user multiple input-multiple output transmission from K transmit antennas, in which K is an integer at least equal to two.

6. The method according to claim 1, wherein there are at least two of the selected N users whose downlink frequency resources only partially overlap with one another.

7. The method according to claim 1, where the indication of the selected power level is a bit sequence of length i wherein 2ⁱ=J;

i is an integer at least equal to two; and

the indication is sent in a downlink control channel.

8. The method according to claim 7, in which i is at least equal to three, and the method is executed by an access node of a wireless communications network.

9. An apparatus comprising at least one processor, a memory storing a set of J predetermined power level offsets that scale transmission power per user, and at least one transmitter,

in which the at least one processor is configured to select a set of N users to which are allocated overlapping downlink frequency resources, and to select from the stored set a power level offset;

and in which the at least one transmitter is configured to signal to at least one of the N users an indication of the selected power level offset and to send a multiplexed transmission to the N users in which the transmission to the at least one of the N users is sent with the selected power level offset;

in which N is an integer at least equal to two, J is an integer at least equal to two, and at least one member of the set is other than 1/n in which n is any positive integer less than N_max in which N_max is a maximum number of users that can be multiplexed together.

10. The apparatus according to claim 9,

wherein the processor is configured to select the power level offset from the stored set by:

determining at the at least one processor a total number L of logical resources that are allocated to all of the selected N users across a subframe;

determining at the at least one processor a unique number U of the frequency resources over which the total number of logical resources are distributed; and

selecting from the set the power level based on a ratio U/L of the unique number of frequency resources to the total number of logical resources, in which U and L are each integers greater than two;

and wherein the at least one transmitter is configured to send the multiplexed transmission across all U of the unique frequency resources.

11. The apparatus according to claim 9, in which the at least one processor is configured to select the power level by selecting from the set a power level offset that is nearest to but not exceeding 100% of maximum transmit power usage.

12. The apparatus according to claim 9, wherein the frequency resources are allocated physical resource blocks within a subframe and wherein the transmitter is configured to signal the selected power level offset to all of the N users and the multiplexed transmission is sent to all of the N users with the selected power level offset.

13. The apparatus according to claim 9, further comprising at least K transmit antennas, in which the at least one transmitter is configured to send the multiplexed transmission as a multi-user multiple input-multiple output transmission from K of the transmit antennas, in which K is an integer at least equal to two.

14. The apparatus according to claim 9, wherein there are at least two of the selected N users whose downlink frequency resources only partially overlap with one another.

15. The apparatus according to claim 9, where the indication of the selected power level is a bit sequence of length i wherein 2ⁱ=J and i is an integer at least equal to two;

and where the at least one transmitter is configured to send the indication in a downlink control channel.

16. The apparatus according to claim 15, in which i is at least equal to three, and the apparatus comprises an access node of a wireless communications network.

17. A method comprising:

receiving by at least one receiver from a network an indication of a selected power level offset;

based on the received indication, selecting by at least one processor a power level offset from a set of J predetermined power level offsets that are stored in a local memory, in which at least one member of the set is other than 1/n in which n is any positive integer less than N_max in which N_max is a maximum number of users that can be multiplexed together; and

receiving, by the at least one receiver, downlink signaling in each of at least one frequency resource in a spatial channel of a multiplexed transmission from the network that was sent with a power level according to the selected power level offset.

18. The method according to claim 17, in which receiving the indication is of length i in which 2ⁱ=J.

19. The method according to claim 17, in which the received indication is received from K transmit antennas, in which K is an integer at least equal to two.

20. The method according to claim 17, executed by a user equipment which receives the indication and the downlink signaling from an access node of a wireless communication system.