System and method for managing inter-cluster handoff of clients which traverse multiple DIDO clusters

• US 20110003606A1
• Filed: 06/16/2010
• Published: 01/06/2011
• Est. Priority Date: 04/02/2004
• Status: Active Grant

• Current Assignee: Rearden, LLC
• Original Assignee: Rearden, LLC
• Inventors: Forenza, Antonio, Perlman, Stephen G.
• Granted Patent: US 9,826,537 B2
• Time in Patent Office: Days
• US Class Current: 455/501
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• 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 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0029 Reduction of the amount of signalling, e.g. retention of useful signalling or differential signalling power control H04W52/04
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 25/03891 Spatial equalizers MIMO diversity systems H04B7/0413
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

A system and method are described for adjusting communication with a first distributed-input-distributed-output (DIDO) client as the first DIDO client moves from a first DIDO cluster to a second DIDO cluster: For example, in one embodiment of the system and method, different signal strength thresholds are specified and either conventional DIDO precoding and/or DIDO precoding with inter-DIDO-cluster interference (IDCI) cancellation to avoid RF interference at the DIDO client are employed based on measured signal strengths from a main DIDO cluster and an interfering DIDO cluster.

Claims

1. A machine-implemented method for adjusting communication with a first distributed-input-distributed-output (DIDO) client as the first DIDO client moves from a first DIDO cluster to a second DIDO cluster, the method comprising:

detecting signal strength between the first DIDO client and the first DIDO cluster (“

S1”

) and between the first DIDO client and the second DIDO cluster (“

S2”

);

when the first DIDO client is within a first specified zone in which S2 is sufficiently low with respect to S1, then implementing conventional DIDO precoding on at least one of the base transceiver stations (BTSs) in the first DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to a first plurality of DIDO clients including the first client, and implementing conventional DIDO precoding on the BTSs in the second DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to a second plurality of DIDO clients not including the first client;

when the first DIDO client is within a second specified zone in which S2 has increased relative to S1 and/or S1 has decreased relative to S2 such that the relative values of S2 and S1 have resulted in a first threshold being reached, then generating channel state information (CSI) defining channel state between one or more antennas of the first DIDO client and one or more antennas of the second DIDO cluster, wherein a BTS of the second DIDO cluster uses the CSI to implement DIDO precoding with inter-DIDO-cluster interference (IDCI) cancellation to avoid RF interference at the first DIDO client;

when the first DIDO client is within a third specified zone in which S2 has increased relative to S1 and/or S1 has decreased relative to S2 such that the relative values of S2 and S1 have resulted in a second threshold being reached, then implementing conventional DIDO precoding on the BTSs in the second DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to the second plurality of DIDO clients including the first client and generating channel state information (CSI) defining channel state between one or more antennas of the first DIDO client and one or more antennas of the first DIDO cluster, wherein a BTS of the first DIDO cluster uses the CSI to implement DIDO precoding with inter-DIDO-cluster interference (IDCI) cancellation to avoid RF interference at the first client; and

when the first DIDO client is within a fourth specified zone in which S2 has increased relative to S1 and/or S1 has decreased relative to S2 such that the relative values of S2 and S1 have resulted in a third threshold being reached, then implementing conventional DIDO precoding on at least one of the base transceiver stations (BTSs) in the second DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to the second plurality of DIDO clients including the first client, and implementing conventional DIDO precoding on the BTSs in the first DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to the first plurality of DIDO clients not including the first client.

2. The method as in claim 1 further comprising:

calculating the signal-to-interference-plus-noise ratio (SINR) and/or the signal-to-interference ratio (SIR) for S1 and S2; and

defining the first, second and third thresholds based on values of SIR and/or SINR.

3. The method as in claim 1 further comprising:

adjusting each of the first through third threshold values dynamically to implement a hysteresis loop in response to the first DIDO client moving between zones to avoid repetitive switches between each of the zones based on the relative values of S1 and S2.

4. The method as in claim 1 wherein a determination as to the zone in which the DIDO client currently resides is made by the DIDO client.

5. The method as in claim 1 wherein a determination as to the zone in which the DIDO client currently resides is made by a BTS in the first DIDO cluster and/or the second DIDO cluster.

6. The method as in claim 1 implemented with a finite state machine, the finite state machine implemented as a processor executing sequences of instructions.

7. The method as in claim 1 wherein implementing DIDO precoding with IDCI cancellation to avoid RF interference at the first DIDO client comprises a plurality of transmitting radio frequency (RF) signals to create locations in space with zero RF energy.

8. The method as in claim 7 wherein M distributed transmitting antennas create up to (M−

1) points of zero RF energy.

9. The method as in claim 7 wherein the locations of zero RF energy are receivers, 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 interfering signals to be simultaneously transmitted.

10. The method as in claim 9 using block diagonalization precoding.

11. A system for adjusting communication with a first distributed-input-distributed-output (DIDO) client as the first DIDO client moves from a first DIDO cluster to a second DIDO cluster, the method comprising:

the first DIDO client detecting signal strength between the first DIDO client and the first DIDO cluster (“

S1”

) and between the first DIDO client and the second DIDO cluster (“

S2”

);

when the first DIDO client is within a first specified zone in which S2 is sufficiently low with respect to S1, then implementing conventional DIDO precoding on at least one of the base transceiver stations (BTSs) in the first DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to a first plurality of DIDO clients including the first client, and implementing conventional DIDO precoding on the BTSs in the second DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to a second plurality of DIDO clients not including the first client;

when the first DIDO client is within a second specified zone in which S2 has increased relative to S1 and/or S1 has decreased relative to S2 such that the relative values of S2 and S1 have resulted in a first threshold being reached, then generating channel state information (CSI) defining channel state between one or more antennas of the first DIDO client and one or more antennas of the second DIDO cluster, wherein a BTS of the second DIDO cluster uses the CSI to implement DIDO precoding with inter-DIDO-cluster interference (IDCI) cancellation to avoid RF interference at the first DIDO client;

when the first DIDO client is within a third specified zone in which S2 has increased relative to S1 and/or S1 has decreased relative to S2 such that the relative values of S2 and S1 have resulted in a second threshold being reached, then implementing conventional DIDO precoding on the BTSs in the second DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to the second plurality of DIDO clients including the first client and generating channel state information (CSI) defining channel state between one or more antennas of the first DIDO client and one or more antennas of the first DIDO cluster, wherein a BTS of the first DIDO cluster uses the CSI to implement DIDO precoding with inter-DIDO-cluster interference (IDCI) cancellation to avoid RF interference at the first client; and

when the first DIDO client is within a fourth specified zone in which S2 has increased relative to S1 and/or S1 has decreased relative to S2 such that the relative values of S2 and S1 have resulted in a third threshold being reached, then implementing conventional DIDO precoding on at least one of the base transceiver stations (BTSs) in the second DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to the second plurality of DIDO clients including the first client, and implementing conventional DIDO precoding on the BTSs in the first DIDO cluster to transmit simultaneous non-interfering data streams within the same frequency band to the first plurality of DIDO clients not including the first client.

12. The system as in claim 11 further comprising:

the first client and/or the BTSs calculating the signal-to-interference-plus-noise ratio (SINR) and/or the signal-to-interference ratio (SIR) for S1 and S2; and

defining the first, second and third thresholds based on values of SIR and/or SINR.

13. The system as in claim 11 further comprising:

the first DIDO client and/or the BTSs adjusting each of the first through third threshold values dynamically to implement a hysteresis loop in response to the first DIDO client moving between zones to avoid repetitive switches between each of the zones based on the relative values of S1 and S2.

14. The system as in claim 11 wherein a determination as to the zone in which the DIDO client currently resides is made by the DIDO client.

15. The system as in claim 11 wherein a determination as to the zone in which the DIDO client currently resides is made by a BTS in the first DIDO cluster and/or the second DIDO cluster.

16. The system as in claim 11 implemented with a finite state machine, the finite state machine implemented as a processor executing sequences of instructions.

17. The system as in claim 11 wherein implementing DIDO precoding with IDCI cancellation to avoid RF interference at the first DIDO client comprises a plurality of transmitting radio frequency (RF) signals to create locations in space with zero RF energy.

18. The system as in claim 17 wherein M distributed transmitting antennas create up to (M−

1) points of zero RF energy.

19. The system as in claim 17 wherein the locations of zero RF energy are receivers, 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 interfering signals to be simultaneously transmitted.

20. The system as in claim 19 using block diagonalization precoding.