System and method for adjusting DIDO interference cancellation based on signal strength measurements

• US 8,971,380 B2
• Filed: 05/01/2012
• Issued: 03/03/2015
• Est. Priority Date: 04/02/2004
• Status: Active Grant

• Current Assignee: Rearden, LLC
• Original Assignee: Rearden, LLC
• Inventors: Forenza, Antonio, Perlman, Stephen G.
• Primary Examiner(s): HA, DAC V
• Application Number:
  US13/461,682
• Publication Number:
  US 20130034130A1
• Time in Patent Office: 1,036 Days
• Field of Search: 375/140, 375/141, 375/144, 375/147, 375/148, 375/220, 375/260, 375/267, 375/285, 375/346, 375/347, 375/349, 370/203, 370/204, 370/278, 370/281, 370/282, 370/317, 370/318, 370/319, 370/328, 370/330, 370/464, 370/465, 370/480, 455/13.4, 455/501, 455/507, 455/524, 455/63.1, 455/67.11, 455/67.13, 455/101, 455/134, 455/135, 4552261-2264
• US Class Current: 375/141
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/0342 QAM
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI

Abstract

A machine-implemented system and method are described for removing interference between adjacent distributed-input-distributed-output (DIDO) clusters comprising. For example, a method according to one embodiment comprises: detecting signal strength at a first client from a main DIDO cluster; detecting interference signal strength at the first client from an interfering DIDO cluster; if the signal strength from the main DIDO cluster reaches a specified value relative to the value of the interference signal strength from the interfering DIDO cluster, then generating channel state information (CSI) defining channel state between one or more antennas of the first client and one or more antennas of the interfering DIDO cluster; transmitting the CSI from the first client to a base transceiver station (BTS) in the interfering DIDO cluster; and implementing DIDO precoding with inter-DIDO-cluster interference (IDCI) cancellation at the BTS in the interfering DIDO cluster to avoid RF interference at the first client.

Claims

1. A machine-implemented method for removing interference between adjacent multiuser (MU) multi antenna system (MU-MAS) clusters comprising:

detecting signal strength at a first client from a first MU-MAS cluster;

detecting interference signal strength at the first client from a second MU-MAS cluster;

if the signal strength from the first MU-MAS cluster reaches a specified value relative to the value of the interference signal strength from the second MU-MAS cluster, then generating channel state information (CSI) defining channel state between one or more antennas of the first client and one or more antennas of the second MU-MAS cluster; and

implementing MU-MAS precoding at a base transceiver station (BTS) in the second MU-MAS cluster based on the CSI to reduce RF interference at the first client.

2. The method as in claim 1 further comprising:

determining whether the specified value of the signal strength from the first MU-MAS cluster reaches the specified value relative to the value of the interference signal strength from the second MU-MAS cluster by estimating a signal-to-interference ratio (SIR) at the first client, the SIR based on a ratio of the signal strength detected by the first client from the first MU-MAS cluster and the interference signal strength detected by the first client from the second MU-MAS cluster; and

generating channel state information (CSI) defining channel state between one or more antennas of the first client and one or more antennas of the second MU-MAS cluster when the SIR moves below a specified threshold.

3. The method as in claim 1 further comprising:

determining whether the specified value of the signal strength from the first MU-MAS cluster reaches the specified value relative to the value of the interference signal strength from the second MU-MAS cluster by estimating a signal-to-interference-plus noise ratio (SINR) at the first client, the SINR based on a ratio of the signal strength detected by the first client from the first MU-MAS cluster and the interference signal strength and noise signal strength detected by the first client from the second MU-MAS cluster; and

generating channel state information (CSI) defining channel state between one or more antennas of the first client and one or more antennas of the second MU-MAS cluster when the SINR moves below a specified threshold.

4. The method as in claim 1 further comprising:

implementing conventional MU-MAS precoding on BTSs of the first MU-MAS cluster to transmit simultaneous non-interfering data streams within the same frequency band to a first plurality of MU-MAS clients including the first client;

implementing conventional MU-MAS precoding on BTSs of the second MU-MAS cluster to transmit simultaneous non-interfering data streams within the same frequency band to a second plurality of MU-MAS clients, the conventional MU-MAS precoding implemented concurrently with the inter-MU-MAS-cluster interference cancellation precoding.

5. The method as in claim 1 wherein detecting interference signal strength at the first client from an second MU-MAS cluster comprises measuring signal strength during designated periods of silence from the MU-MAS antennas of the first MU-MAS cluster.

6. The method as in claim 5 wherein the designated periods of silence are designated based on a predetermined transmission frame structure.

7. The methods as in claim 1 wherein the first MU-MAS cluster and the second MU-MAS cluster comprise multicarrier orthogonal frequency-division multiplexing (OFDM) systems, the method further comprising:

determining whether the specified value of the signal strength from the first MU-MAS cluster reaches the specified value relative to the value of the interference signal strength from the second MU-MAS cluster by estimating a signal-to-interference ratio (SIR) or signal-to-interference-plus-noise ratio (SINR) at the first client, the SIR based on a ratio of the signal strength detected by the first client from the first MU-MAS cluster and the interference signal strength detected by the first client from the second MU-MAS cluster, the SINR based on a ratio of the signal strength detected by the first client from the first MU-MAS cluster and the interference signal strength and noise signal strength detected by the first client from the second MU-MAS cluster, wherein the SIR or SINR is estimated from null tones of the ODFM system.

8. The method as in claim 1 wherein if the signal strength from the first MU-MAS cluster reaches a specified value relative to the value of the interference signal strength from the second MU-MAS cluster, then using training signals from the second MU-MAS cluster to generate the channel state information (CSI) defining channel state between one or more antennas of the first client and one or more antennas of the second MU-MAS cluster.

9. The method as in claim 1 wherein implementing MU-MAS precoding with inter-MAS-cluster interference (IMCI) cancellation at the BTS in the second MU-MAS cluster comprises precoding and transmitting radio frequency (RF) signals to create zero RF energy at the location of the first client.

10. The method as in claim 9 wherein M distributed transmitting antennas in the second cluster create up to (M−

1) points of zero RF energy.

11. The method as in claim 9 wherein the transmitting antennas are aware of the channel state information between the transmitters and the receivers, and the transmitters utilize the channel state information to determine the second signals to be simultaneously transmitted.

12. The method as in claim 11 using block diagonalization precoding.