US 10,477,585 B1Granted

Microwave interference mitigation

AssigneeAmazon Technologies, Inc.

InventorsKun Ting Tsai, Chirag Bhavsar, Huanchun Ye, Varadarajan Gopalakrishnan, QingYun Wei, Morris Hsu, James Edwin Christy

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Abstract

Microwave interference mitigation techniques and systems are disclosed herein. In some embodiments, microwave interference mitigation involves coordinating wireless traffic in accordance with a magnetron's on-and-off cycle so that data is not sent during the magnetron's on period, and is exclusively sent during the magnetron's off period. Wireless traffic can be coordinated using a voltage monitoring and zero-crossing point detection technique coupled with a Clear To Send (CTS) packet. For non-microwave devices, wireless traffic coordination can be achieved using a pattern matching algorithm coupled with a Clear Channel Assessment (CCA) threshold adjustment during the magnetron's on-and-off cycles. Additional, or alternative, microwave interference mitigation techniques involve decreasing a maximum packet size for data packets that are to be transmitted wirelessly in the environment, which guarantees successful transmission of data packets during the magnetron's off periods.

Claims20

Dependent claims

A microwave oven comprising:

a magnetron configured to operate in accordance with an on-and-off cycle where the magnetron emits microwave energy during an ‘on’ period of the on-and-off cycle and the magnetron does not emit microwave energy during an ‘off’ period of the on-and-off cycle;
a WiFi radio chip configured to operate in an environment of the microwave oven;
a microcontroller configured to determine that the magnetron is operating by determining that a voltage supplied to the magnetron transitions from a first voltage value greater than a threshold voltage to a second voltage value less than the threshold voltage;
and
logic configured to:
determine a start time of the ‘on’ period, wherein the start time corresponds to a zero-crossing point between an input power associated with the magnetron and an electrical current associated with the magnetron;
broadcast, via the WiFi radio chip, a Clear To Send (CTS) packet before the start time, the CTS packet including:
a destination address of the microwave oven;
and
a Network Allocation Vector (NAV) that specifies a duration corresponding to the ‘on’ period;
and
cause the microwave oven to refrain from sending data via the WiFi radio chip during the ‘on’ period.

9 more elements

A method, comprising:

determining, by a wireless communication device, that a magnetron is operating in an environment of the wireless communication device, the magnetron operating in accordance with an on-and-off cycle where the magnetron emits microwave energy during an ‘on’ period of the on-and-off cycle and the magnetron does not emit microwave energy during an ‘off’ period of the on-and-off cycle;
determining, by the wireless communication device, a start time of the ‘on’ period, wherein the start time corresponds to a zero-crossing point between an input power associated with the magnetron and an electrical current associated with the magnetron;
sending, by the wireless communication device, a Clear To Send (CTS) packet before the start time of the ‘on’ period, wherein the CTS packet specifies a duration that is based at least in part on the ‘on’ period;
sending, by the wireless communication device, data during the ‘off’ period;
and
ceasing, by the wireless communication device, the sending of the data during the ‘on’ period.

3 more elements

A wireless communication device comprising:

a wireless transceiver configured to operate in an environment of the wireless communication device;
and
logic configured to:
determine that a magnetron in the environment is operating, the magnetron operating in accordance with an on-and-off cycle where the magnetron emits microwave energy during an ‘on’ period of the on-and-off cycle and the magnetron does not emit microwave energy during an ‘off’ period of the on-and-off cycle;
determine a start time of the ‘on’ period, wherein the start time corresponds to a zero-crossing point between an input power associated with the magnetron and an electrical current associated with the magnetron;
send a Clear To Send (CTS) packet before the start time of the ‘on’ period, wherein the CTS packet specifies a duration that is based at least in part on the ‘on’ period;
send data during the ‘off’ period;
and
cease sending the data during the ‘on’ period.

6 more elements

Dependencies are inferred from the claim text.