Preamble structure supporting full duplex communications
A method at a network node that is configured to simultaneously transmit and receive wireless RF signals, comprising: transmitting, from the network node, a downlink message, the downlink message having a preamble that includes channel estimation information for estimating a self-interference channel; monitoring at the network node, during an initial duration while transmitting the downlink message, for the channel estimation information, and estimating a self-interference channel based on received portions of the channel estimation information; and using the estimated self-interference channel to cancel self-interference while receiving an uplink message and simultaneously transmitting a remainder of the downlink message.
1. A method at a network node that is configured to simultaneously transmit and receive wireless RF signals, the method comprising:
transmitting, from the network node, a downlink message having a preamble that includes channel estimation information followed by a data portion;
monitoring, at the network node, a frequency channel for the channel estimation information included in the downlink message, and prior to transmitting the data portion of the downlink message, estimating and cancelling a self-interference channel in the frequency channel based on the monitored channel estimation information; and
receiving, at the network node, an uplink message in the frequency channel during a time period that overlaps with transmitting the data portion of the downlink message,
wherein auto-detection information is included in the preamble of the downlink message, and theauto-detection information in the preamble comprises information encoded using a different modulation than other information in the preamble.
2. The method of claim 1 wherein the network node transmits the downlink message in a frequency channel that is the same as the frequency channel.
3. The method of claim 1 wherein the network node transmits the downlink message using a frequency channel that is adjacent to the frequency channel.
4. The method of claim 1 wherein the downlink message is transmitted in a first spatial stream in the frequency channel to a first wireless station, and the uplink message is received in a second spatial stream in the frequency channel from a second wireless station.
5. The method of claim 1 wherein the channel estimation information is included sufficiently early in the preamble to permit the network node to estimate the self-interference channel prior to transmission of the data portion by the network node.
6. The method of claim 5 including monitoring the frequency channel for the auto-detection information prior to the channel estimation information.
7. The method of claim 5 wherein the channel estimation information includes one or more long training fields that are each populated with a channel estimation sequence.
8. The method of claim 7 wherein each channel estimation sequence includes a Golay sequence.
9. The method of claim 5 wherein the preamble includes a group of intermediate fields that are not long training fields following the channel estimation information, and at least one or more additional long training fields after the intermediate fields, the one or more additional long training fields including channel estimation sequences for use by a remote receiver to estimate a channel.
10. The method of claim 1 wherein the auto-detection information is encoded using quadrature binary phase shift keying and the other information is encoded using binary phase shift keying.
11. The method of claim 1 wherein the preamble comprises a legacy preamble portion followed by a further preamble portion, the auto-detection information being included at a beginning of the further preamble portion, wherein the auto-detection information is encoded using a first modulation and all other information in the preamble is encoded using a second modulation.
12. A network node for simultaneously transmitting and receiving wireless RF signals, the network node configured to:
transmit a downlink message having a preamble that includes channel estimation information followed by a data portion;
monitor a frequency channel for the channel estimation information;
prior to transmitting the data portion of the downlink message, estimate and cancel a self-interference channel in the frequency channel based on the monitored channel estimation information; and
receive an uplink message in the frequency channel during a time period that overlaps with the network node transmitting the data portion of the downlink message,
wherein auto-detection information is included in the preamble of the downlink message, and the auto-detection information in the preamble comprises information encoded using a different modulation than other information in the preamble.
13. The network node of claim 12 wherein the network node is configured to transmit the downlink message in a frequency channel that is the same as the frequency channel.
14. The network node of claim 12 wherein the network node is configured to transmit the downlink message using a frequency channel that is adjacent to the frequency channel.
15. The network node of claim 12 wherein the network node is configured to transmit the downlink message in a first spatial stream in the frequency channel to a first wireless station, and receive the uplink message in a second spatial stream in the frequency channel from a second wireless station.
16. The network node of claim 12 wherein the channel estimation information is included sufficiently early in the preamble to permit the network node to estimate the self-interference channel prior to transmission of the data portion by the network node.
17. The network node of claim 16 wherein the network node is configured to include the auto-detection information in the preamble before the channel estimation information and the network node is configured to monitor the frequency channel for the auto-detection information.
18. The network node of claim 12 wherein the network node is an access point in a local wireless area network.
19. The network node of claim 12 wherein the auto-detection information is encoded using quadrature binary phase shift keying and the other information is encoded using binary phase shift keying.
20. A method comprising:
receiving, in a frequency channel at a station, at least an initial portion of a downlink message from a node, the downlink message including a preamble that includes channel estimation information followed by a data portion, wherein the node uses the channel estimation information to estimate and cancel a self-interference channel prior to transmission of the data portion of the downlink message, wherein auto-detection information is included in the preamble, and the auto-detection information in the preamble comprises information encoded using a different modulation than other information in the preamble; and
transmitting, at the station, an uplink message for the node in the frequency channel in response to receiving the initial portion during a time period that overlaps with transmission of the data portion of the downlink message.