Method of grouping transmitter-receiver pairs for communicating over a communications network

• US 9,531,461 B2
• Filed: 12/19/2012
• Issued: 12/27/2016
• Est. Priority Date: 12/23/2011
• Status: Active Grant

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Saadani, Ahmed, Ben Halima, Slim
• Primary Examiner(s): Joseph, Jaison
• Application Number:
  US14/365,003
• Publication Number:
  US 20140348256A1
• Time in Patent Office: 1,469 Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/046 taking physical layer constraints into account
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 72/121 for groups of terminals or users
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

Disclosed is a method of grouping transmitter-receiver pairs for communicating over a communications network. For each group of a set of groups of transmitter-receiver pairs, the pairs of the group execute an iterative interference alignment technique for I1 iterations on signals transmitted by the group. Each transmitter of the group successively sends a pilot signal that has been precoded by a matrix resulting from that execution. Each receiver of the group evaluates a metric representative of a distance between a vector subspace generated by the pilot signal transmitted by the transmitter with which it forms a pair and a vector subspace generated by interferences determined from the pilot signals transmitted by the other transmitters. A central unit calculates a global metric associated for each group on the basis of the metrics from the receivers of the group and selects from the set a group that optimizes the global metric.

Claims

1. A method of grouping a predetermined number NG of transmitter-receiver pairs for communicating over a communications network, said method comprising:

for each group of a determined set of groups comprising NG transmitter-receiver pairs;

an execution process in which the NG pairs of said group execute an iterative interference alignment technique for a predetermined number I1 of iterations on the signals transmitted by said group;

a sending process in which each transmitter of the NG pairs of said group sends a pilot signal precoded with the help of a matrix resulting from executing said iterative interference alignment technique, the transmitters of the NG pairs of said group successively transmitting the pilot signals; and

an evaluation process in which each receiver of the NG pairs of said group evaluate a metric representative of a distance between a vector subspace generated by the precoded pilot signal transmitted by the transmitter with which the receiver forms a transmitter-receiver pair and a vector subspace generated by the interferences affecting the pilot signal as determined from the precoded pilot signals transmitted by the other transmitters of the group;

a calculation process in which a central unit of the network calculates a global metric associated with each group of the determined set of groups on the basis of the metrics evaluated by the receivers of the NG pairs of the group; and

a selection process in which the central unit selects from the determined set of groups a group that optimizes the global metric for communicating over the network.

2. A grouping method according to claim 1, wherein after the selection process, the pairs of the group selected for communicating over the communications network execute said iterative interference alignment technique on the signals transmitted by said selected group for a number I2 of iterations that is greater than the number I1.

3. A selection method in which a central unit of a communications network selects a group having a predetermined number NG of transmitter-receiver pairs for communicating over said network, said method comprising:

for each group of a determined set of groups comprising NG transmitter-receiver pairs, an obtaining process of obtaining metrics evaluated by the receivers of the NG pairs of said group after execution of an interference alignment technique by said group during a predetermined number I1 of iterations on signals transmitted by the group, and after receiving pilot signals transmitted successively by the transmitters of the NG pairs of said group, the pilot signals being precoded with the help of matrices resulting from executing the iterative interference alignment technique, each metric evaluated by a receiver of said group being representative of a distance between a vector subspace generated by the precoded pilot signal transmitted by the transmitter with which the receiver forms a transmitter-receiver pair, and a vector subspace generated by interferences affecting this precoded pilot signal as determined from the precoded pilot signals transmitted by the other transmitters of the group;

a calculation process of calculating a global metric associated with each group of said determined set of groups on the basis of the metrics evaluated by the receivers of the NG pairs of the group; and

a selection process of selecting from the determined set of groups a group that optimizes the global metric for communicating over the network.

4. A selection method according to claim 3, wherein the global metric associated with a group is equal to the sum of the metrics evaluated by the receivers of the NG pairs of the group.

5. A non-transitory computer readable medium having stored thereon a computer program including instructions for executing the selection method according to claim 3 when said program is executed by a computer.

6. An evaluation method for evaluating a metric by a receiver of a communications network, said receiver forming a transmitter-receiver pair with a transmitter of the network, the pair belonging to a group having a predetermined number NG of transmitter-receiver pairs, said evaluation method comprising:

an execution process of executing an iterative interference alignment technique during a predetermined number I1 of iterations on signals transmitted by said group;

a reception process of receiving pilot signals transmitted successively by the transmitters of the NG pairs of said group, which pilot signals are precoded with the help of matrices resulting from executing the iterative interference alignment technique; and

an evaluation process of evaluating a metric representative of a distance between a vector subspace generated by the precoded pilot signal transmitted by the transmitter with which the receiver forms a transmitter-receiver pair, and a vector subspace generated by interferences affecting this precoded pilot signal and determined from the precoded pilot signals transmitted by the other transmitters of the group.

7. A method of evaluating a metric according to claim 6, the method further comprising a transmission step process of transmitting said metric to a transmitter with which said receiver forms said pair or to a central unit of the communications network.

8. A method of evaluating a metric according to claim 6, wherein the evaluated metric is representative of a chord distance between said vector subspaces.

9. A method of evaluating a metric according to claim 6, wherein the receiver is provided with MR receive antennas, and wherein the subspace generated by the interferences taken into consideration for evaluating the metric is the vector subspace generated by the MR-1 strongest interferences.

10. A non-transitory computer readable medium having stored thereon a computer program including instructions for executing the selection method of claim 6 when said program is executed by a computer.

11. A central unit of a communications network suitable for selecting a group for communicating over said network, said group comprising a predetermined number NG of transmitter-receiver pairs, and said central unit comprising:

a processor configured to obtain metrics for each group of a determined set of groups, each comprising NG transmitter-receiver pairs, the metrics being evaluated by the receivers of the NG pairs of said group after said group has executed an interference alignment technique for a predetermined number I1 of iterations on signals transmitted by the group and after receiving pilot signals transmitted successively by the transmitters of the NG pairs of said group, the pilot signals being precoded with the help of matrices resulting from executing the iterative interference alignment technique, each metric evaluated by a receiver of said group being representative of a distance between a vector subspace generated by the precoded pilot signal transmitted by the transmitter with which the receiver forms a transmitter-receiver pair, and a vector subspace generated by interferences affecting the precoded pilot signal and determined from precoded pilot signals transmitted by the other transmitters of the group;

a processor configured to calculate a global metric associated with each group of the determined set of groups on the basis of the metrics evaluated by the receivers of the NG pairs of the group; and

a processor configured to select from the determined set of groups a group that optimizes the global metric for communicating over the network.

12. A receiver of a communications network, said receiver forming a transmitter-receiver pair with a transmitter of the network, the pair belonging to a group having NG transmitter-receiver pairs, said receiver comprising:

a processor configured to execute an iterative interference alignment technique during a predetermined number I1 of iterations on signals transmitted by said group;

wherein said receiver is configured to receive pilot signals transmitted successively by the transmitters of the NG pairs of said group and precoded with the help of matrices resulting from executing the iterative interference alignment technique; and

wherein said receiver comprises a processor configured to evaluate a metric representative of a distance between a vector subspace generated by the precoded pilot signal transmitted by the transmitter with which the receiver forms a transmitter-receiver pair, and a vector subspace generated by interferences affecting this precoded pilot signal as determined from precoded pilot signals transmitted by the other transmitters of the group.

13. A communications network system comprising:

a plurality of transmitter-receiver pairs, each formed by a transmitter and a receiver; and

a central unit suitable for selecting from said plurality of transmitter-receiver pairs a group having a predetermined number NG of transmitter-receiver pairs for communicating over the communications network;

wherein said transmitter comprises a processor configured to execute an iterative interference alignment technique during a predetermined number I1 of iterations on signals transmitted by said group and wherein said transmitter is configured to send a pilot signal that is precoded with the help of a matrix resulting from executing the iterative interference alignment technique;

wherein said receiver a comprises a processor configured to execute an iterative interference alignment technique during a predetermined number I1 of iterations on signals transmitted by said group, wherein said receiver is configured to receive pilot signals transmitted successively by the transmitters of the NG pairs of said group and precoded with the help of matrices resulting from executing the iterative interference alignment technique, and wherein said receiver comprises a processor configured to evaluate a metric representative of a distance between a vector subspace by the precoded pilot signal transmitted by the transmitter with which the receiver forms a transmitter-receiver pair, and a vector subspace generated by interferences affecting this precoded pilot signal as determined from precoded pilot signals transmitted by the other transmitters of the group; and

wherein said central unit comprises;

a processor configured to obtain metrics for each group of a determined set of groups, each comprising NG transmitter-receiver pairs, the metrics being evaluated by the receivers of the NG pairs of said group after said group has executed an interference alignment technique for a predetermined number I1 of iterations on signals transmitted by the group and after receiving pilot signals transmitted successively by the transmitters of the NG pairs of said group, the pilot signals being precoded with the help of matrices resulting from executing the iterative interference alignment technique, each metric evaluated by a receiver of said group being representative of a distance between a vector subspace generated by the precoded pilot signal transmitted by the transmitter with which the receiver forms a transmitter-receiver pair, and a vector subspace generated by interferences affecting the precoded pilot signal and determined from precoded pilot signals transmitted by the other transmitters of the group;

a processor configured to calculate a global metric associated with each group of the determined set of groups on the basis of the metrics evaluated by the receivers of the NG pairs of the group; and

a processor configured to select from the determined set of groups a group that optimizes the global metric for communicating over the network.