Dynamic signal filter in multi-antenna system

• US 10,164,722 B1
• Filed: 12/16/2015
• Issued: 12/25/2018
• Est. Priority Date: 12/16/2015
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Napoles, Adrian, Khasgiwala, Mudit Sunilkumar
• Primary Examiner(s): Towfighi, Afshawn M
• Application Number:
  US14/971,719
• Time in Patent Office: 1,105 Days
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• CPC Class Codes: H04B 1/715 Interference-related aspects
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 2001/1063 using a notch filter

Abstract

A processing device tracks a frequency hopping sequence implemented by a personal area network (PAN) transmitter in a user device and identifies a set of filter coefficients corresponding to a first frequency of a plurality of frequencies in the frequency hopping sequence, wherein the PAN transmitter is currently transmitting a PAN signal at the first frequency. The processing device configures a tunable notch filter with the set of filter coefficients to cause the filter to remove at least a portion of a PAN component at the current frequency from a combined signal received at a wireless local area network (WLAN) receiver in the user device, the combined signal comprising a WLAN component attributable to a received WLAN signal and the PAN component attributable to the PAN signal.

Claims

1. A method comprising:

determining a plurality of sets of filter coefficient values, each set corresponding to a different respective frequency of a plurality of frequencies in a frequency hopping sequence;

transmitting a BLUETOOTH®

wireless signal at the plurality of frequencies in the frequency hopping sequence over time using a first antenna in a user device;

receiving a combined signal via a second antenna in the user device, the combined signal comprising a received WI-FI®

wireless signal at 2.4 gigahertz and the BLUETOOTH®

wireless signal;

determining, by a processing device, that a received signal strength indicator (RSSI) of the WI-FI®

wireless signal is below a threshold;

identifying, by the processing device, a current frequency of the plurality of frequencies in the frequency hopping sequence being used to transmit the BLUETOOTH®

wireless signal;

identifying a first set of filter coefficient values, from the plurality of sets of the filter coefficient values, the first set corresponding to the current frequency;

setting, by the processing device, one or more filter coefficients of a tunable notch filter in the user device to the first set of filter coefficient values corresponding to the current frequency, the first set of filter coefficient values to cause the tunable notch filter to remove at least a portion of the BLUETOOTH®

wireless signal at the current frequency from the combined signal to generate a filtered signal; and

providing the filtered signal to the processing device for decoding of the filtered signal.

2. The method of claim 1, further comprising:

detecting a change of the current frequency to a second frequency in the frequency hopping sequence; and

setting the one or more filter coefficients of the tunable notch filter to a second set of filter coefficient values corresponding to the second frequency, the second set of filter coefficient values to cause the tunable notch filter to remove at least a portion of the BLUETOOTH®

wireless signal at the second frequency from the combined signal.

3. The method of claim 1, further comprising:

comparing at least one of the RSSI, a packet error rate (PER), a signal to noise ratio (SNR) or a number of packet retransmissions to a corresponding threshold.

4. An apparatus comprising:

a personal area network (PAN) transmitter to transmit a PAN signal at a plurality of frequencies in a frequency hopping sequence over time;

a wireless local area network (WLAN) receiver to receive a combined signal comprising a received WLAN signal and at least a portion of the PAN signal;

a filter coupled to the WLAN receiver;

a memory; and

a processing device, operatively coupled to the memory, the processing device to;

determine a plurality of sets of filter coefficient values, each set corresponding to a different respective frequency of the plurality of frequencies;

track the plurality of frequencies;

identify a first set of filter coefficient values, from the plurality of sets of the filter coefficient values, the first set corresponding to a first frequency of the plurality of frequencies in the frequency hopping sequence at which the PAN transmitter is currently transmitting; and

configure the filter with the first set of filter coefficient values to cause the filter to remove at least a portion of the PAN signal at the first frequency from the combined signal.

5. The apparatus of claim 4, wherein the plurality of sets of filter coefficient values comprises the first set of filter coefficient values and a second set of filter coefficient values, wherein the second set of filter coefficient values corresponds to a second frequency of the plurality of frequencies in the frequency hopping sequence.

6. The apparatus of claim 4, wherein the processing device further to:

determine that a performance level of the WLAN signal is below a threshold by comparing at least one of a received signal strength indicator (RSSI), a packet error rate (PER), a signal to noise ratio (SNR) or a number of packet retransmissions to a corresponding threshold.

7. The apparatus of claim 4, wherein the filter comprises at least one of a tunable analog notch filter or a tunable digital notch filter.

8. The apparatus of claim 4, wherein the PAN signal comprises a BLUETOOTH®

wireless signal and wherein the WLAN signal comprises a WI-FI®

wireless signal.

9. The apparatus of claim 4, further comprising:

a first antenna coupled to PAN transmitter, the PAN transmitter to transmit the PAN signal via the first antenna; and

a second antenna coupled to the WLAN receiver, the WLAN receiver to receive the combined signal via the second antenna.

10. The apparatus of claim 4, wherein the processing device further to:

detect a change of the current frequency to a second frequency in the frequency hopping sequence;

identify a second set of filter coefficient values corresponding to the second frequency; and

configure the filter with the second set of filter coefficient values to cause the filter to remove at least a portion of the PAN signal at the second frequency from the combined signal.

11. A method comprising:

determining a plurality of sets of filter coefficient values, each set corresponding to a different respective frequency of a plurality of frequencies in a frequency hopping sequence;

tracking, by a processing device, the plurality of frequencies;

identifying, by the processing device, a set of filter coefficient values, from the plurality of sets of the filter coefficient values, the first set corresponding to a first frequency of the plurality of frequencies in the frequency hopping sequence at which the transmitter is currently transmitting by accessing the predetermined filter calibration data stored in the memory; and

configuring, by the processing device, a tunable notch filter in the user device with the set of filter coefficient values, the configuring to cause the tunable notch filter to remove at least a portion of a signal at the first frequency received by a receiver in the user device.

12. The method of claim 11, wherein tracking the frequency hopping sequence implemented by the transmitter comprises tracking the frequency hopping sequence implemented by a personal area network (PAN) transmitter.

13. The method of claim 12, wherein configuring the tunable notch filter comprises configuring the tunable notch filter to cause the tunable notch filter to remove at least a portion of a PAN signal at the first frequency from the signal received by a wireless local area network (WLAN) receiver.

14. The method of claim 13, further comprising:

determining that a performance level of the signal received by the WLAN receiver is below a threshold; and

initiating a filter adaptation routine to configure the tunable notch filter.

15. The method of claim 14, wherein determining that the performance level of the signal received by the WLAN receiver is below the threshold comprises comparing at least one of a received signal strength indicator (RSSI), a packet error rate (PER), a signal to noise ratio (SNR) or a number of packet retransmissions to a corresponding threshold.

16. The method of claim 11, further comprising:

receiving an indication of transmission of a PAN signal at the first frequency of the plurality of frequencies in the frequency hopping sequence by the PAN transmitter; and

identifying the first frequency of the plurality of frequencies in the frequency hopping sequence from the indication.

17. The method of claim 11, further comprising:

receiving an indication of reception of a combined signal by the WLAN receiver, the combined signal comprising a received WLAN signal and a PAN signal.

18. The method of claim 11, further comprising:

detecting a change of the first frequency to a second frequency in the frequency hopping sequence;

identifying a second set of filter coefficient values corresponding to the second frequency; and

configuring the tunable notch filter with the second set of filter coefficient values to cause the tunable notch filter to remove at least a portion of the signal at the second frequency.

19. The method of claim 11, wherein the signal received by the receiver comprises a combination of a BLUETOOTH®

wireless signal and a WI-FI®

wireless signal.