Systems and methods for transmitting a preamble within a wireless local area network (WLAN)
Some embodiments described herein provide a method for transmitting a preamble in accordance with a wireless local area network communication protocol. In some embodiments, a data frame may be obtained for transmission including a preamble compliant with the wireless local area network communication protocol. It may be determined that the preamble includes a first preamble portion that spans multiple symbol durations and a second preamble portion that spans a single symbol duration. The first preamble portion via beamforming may be transmitted based on a first beamforming matrix. When a transmission mode of the second preamble portion is beamforming, a second beamforming matrix may be generated based on the first beamforming matrix, each tone for the second preamble portion may be calculated based on the second beamforming matrix. Each calculated tone may be transmitted in accordance with the wireless local area network communication protocol.
1. A method for transmitting a preamble in accordance with a wireless local area network communication protocol, the method comprising:
obtaining a data frame for transmission including a preamble compliant with the wireless local area network communication protocol;
determining that the preamble includes a first preamble portion that spans multiple symbol durations and a second preamble portion that spans a single symbol duration;
transmitting the first preamble portion via beamforming based on a first beamforming matrix; and
when a transmission mode of the second preamble portion is beamforming:
generating a second beamforming matrix based on the first beamforming matrix;
calculating each tone from a plurality of tones used to transmit the second preamble portion based on the second beamforming matrix; and
transmitting each calculated tone in accordance with the wireless local area network communication protocol.
2. The method of claim 1 , wherein:
the first preamble portion includes a high efficiency short training field (HESTF), and a high efficiency long training field (HELTF); and
the second preamble portion includes legacy training fields and signaling configuration fields.
3. The method of claim 1 , further comprising:
when the transmission mode of the second preamble portion is omni-directional, transmitting the second preamble portion in omni-direction with no data transmission on guard tones that are configured in accordance with the wireless local area network communication protocol.
4. The method of claim 3 , further comprising:
performing channel estimation using a first training field contained in the first preamble portion even if channel estimation has been performed based on a second training field contained in the second preamble portion.
5. The method of claim 1 , further comprising:
filling guard tones in accordance with the wireless local area network communication protocol with extended symbols.
6. The method of claim 5 , wherein the extended symbols are known symbols for a receiver to perform channel estimation.
7. The method of claim 1 , further comprising:
applying at least one of cyclic delay diversity (CDD) and cyclic shift diversity (CSD) to the preamble.
8. The method of claim 7 , wherein: when the CSD is applied in time domain to the second preamble portion, the same CSD is applied in time domain to the first preamble portion.
9. The method of claim 7 , wherein: when the CDD is applied in frequency domain to the second preamble portion, the same or a different CDD is applied in frequency domain to the first preamble portion.
10. The method of claim 1 , further comprising:
transmitting the second preamble portion via a mixed transmission mode of beamforming and omni-direction, wherein the mixed transmission mode is specified via a data value transmitted with the preamble, or implied by a transmission characteristic of the second preamble portion.
11. A system for transmitting a preamble in accordance with a wireless local area network communication protocol, the system comprising:
processing circuitry configured to:
obtain a data frame for transmission including a preamble compliant with the wireless local area network communication protocol, and
determine that the preamble includes a first preamble portion that spans multiple symbol durations and a second preamble portion that spans a single symbol duration;
a network interface configured to:
transmit the first preamble portion via beamforming based on a first beamforming matrix;
wherein:
when a transmission mode of the second preamble portion is beamforming:
the processing circuitry is configured to generate a second beamforming matrix based on the first beamforming matrix; and
calculate each tone from a plurality of tones used to transmit the second preamble portion based on the second beamforming matrix; and
the network interface is configured to transmit each calculated tone under the wireless local area network communication protocol.
12. The system of claim 11 , wherein:
the first preamble portion includes a high efficiency short training field (HESTF), and a high efficiency long training field (HELTF); and the second preamble portion includes legacy training fields and signaling configuration fields.
13. The system of claim 11 , wherein the network interface is further configured to:
when the transmission mode of the second preamble portion is omni-directional,
transmit the second preamble portion in omni-direction with no data transmission on guard tones that are configured in accordance with the wireless local area network communication protocol.
14. The system of claim 13 , wherein the processing circuitry is further configured to:
perform channel estimation using a first training field contained in the first preamble portion even if channel estimation has been performed based on a second training field contained in the second preamble portion.
15. The system of claim 11 , wherein the processing circuitry is further configured to:
fill guard tones in accordance with the wireless local area network communication protocol with extended symbols.
16. The system of claim 15 , wherein the extended symbols are known symbols for a receiver to perform channel estimation.
17. The system of claim 11 , wherein the processing circuitry is further configured to:
apply cyclic delay diversity (CDD) or cyclic shift diversity (CSD) to the preamble.
18. The system of claim 17 , wherein: when the CSD is applied in time domain to the second preamble portion, the same CSD is applied in time domain to the first preamble portion.
19. The system of claim 17 , wherein: when the CDD is applied in frequency domain to the second preamble portion, the same or a different CDD is applied in frequency domain to the first preamble portion.
20. The system of claim 11 , wherein the network interface is further configured to:
transmit the second preamble portion via a mixed transmission mode of beamforming and omni-direction,
wherein the mixed transmission mode is specified via a data value transmitted with the preamble, or implied by a transmission characteristic of the second preamble portion.