Systems, methods, and devices for interference mitigation in wireless networks
Example systems, methods, and devices for mitigating interference in wireless networks are discussed. One example method includes the operations of passing channel frequency offsets of a plurality of LTF symbols on a plurality of subcarriers through a high pass frequency band, encoding the plurality of LTF symbols with a plurality of LTF sequences across frequency, and encoding the LTF symbols in time and/or frequency. Another example includes the operations of receiving a plurality of LTF symbols on a plurality of subcarriers for channel estimation of one or more streams, removing the encoding across time, removing the encoding across frequency, and removing the LTF sequence(s), and passing the modified LTF symbols through a smoothing filter, for example, a low pass filter for removing the interference due to CFOs. Methods, apparatus, and systems described herein can be applied to 802.11ax or any other wireless standard.
1. A computer-readable non-transitory storage medium that contains computer-executable instructions, which when executed by one or more processors result in performing operations comprising:
identifying one or more data streams comprising one or more encoded long training field (LTF) symbols over a wireless communication channel;
encoding the one or more data streams comprising the one or more LTF symbols using an orthogonal matrix, wherein dimensions of the orthogonal matrix are determined by a number of data streams comprised in the one or more data streams and a number of LTF symbols comprised in the one or more LTF symbols;
determining a first phase of the wireless communication channel using a first LTF symbol of the one or more LTF symbols;
determining a second phase of the wireless communication channel using a second LTF symbol of the one or more LTF symbols;
determining a phase difference between the first phase and the second phase;
determining a channel frequency offset (CFO) of the wireless communication channel using the phase difference; and
determining a wireless communication channel response based at least in part on the determined CFO.
2. The medium of claim 1 , wherein the operations further comprise:
determining a zero-forcing filter or a minimum mean square error estimation (MMSE) filter for mitigating interference on the wireless communication channel due to channel frequency offsets (CFOs) between two or more data streams of the one or more data streams; and
determining a channel response of the one or more data streams.
3. The medium of claim 1 , wherein the first LTF symbol is a first LTF symbol in a sequence of LTF symbols comprised in the one or more data streams, and wherein the second LTF symbol is a later LTF symbol in the same sequence of LTF symbols comprised in the one or more data streams.
4. The medium of claim 1 , wherein the operations further comprise:
determining a number of LTF symbols comprised in the one or more data streams based on a number of data streams determined to be comprised in the wireless communication channel.
5. The medium of claim 4 , wherein the wireless communication channel comprises one or more subbands, and wherein each subband is configured to transmit the one or more data streams comprising the determined number of LTF symbols.
6. The medium of claim 1 , wherein the operations further comprise:
determining the number of data streams comprised in the one or more data streams is less than the number of LTF symbols comprised in the one or more LTF symbols; and
adding one or more additional LTF symbols to the one or more LTF symbols to be encoded in the one or more data streams so that a total number of LTF symbols encoded in the one or more data streams is equal to the determined number of data streams comprised in the one or more data streams, wherein the total number of LTF symbols comprises a first decodable set of LTF symbols and a second decodable set of LTF symbols.
7. A method for mitigating interference in a wireless network, the method comprising:
identifying, by a wireless communication device, one or more data streams comprising one or more encoded long training field (LTF) symbols over a wireless communication channel;
encoding the one or more data streams comprising the one or more LTF symbols using an orthogonal matrix, wherein dimensions of the orthogonal matrix are determined by a number of data streams comprised in the one or more data streams and a number of LTF symbols comprised in the one or more LTF symbols;
determining, by the wireless communication device, a first phase of the wireless communication channel using a first LTF symbol of the one or more LTF symbols;
determining, by the wireless communication device, a second phase of the wireless communication channel using a second LTF symbol of the one or more LTF symbols;
determining, by the wireless communication device, a phase difference between the first phase and the second phase;
determining, by the wireless communication device, a CFO of the wireless communication channel using the determined phase difference; and
determining, by the wireless communication device, the wireless communication channel response based at least in part on the determined CFO.
8. The method of claim 7 , further comprising:
determining, by the wireless communication device, a zero-forcing filter or a minimum mean square error estimation (MMSE) filter for mitigating interference due to channel frequency offsets (CFOs) between two or more data streams; and
determining a channel response of the one or more data streams.
9. The method of claim 7 , wherein the first LTF symbol is a first LTF symbol in a sequence of LTF symbols comprised in the one or more data streams, and wherein the second LTF symbol is a later LTF symbol in the same sequence of LTF symbols comprised in the one or more data streams.
10. The method of claim 7 , wherein the method further comprises:
determining, by the wireless communication device, a number of LTF symbols comprised in the one or more data streams based on a number of data streams determined to be comprised in the wireless communication channel.
11. The method of claim 10 , wherein the wireless communication channel comprises one or more subbands, and wherein each subband is configured to transmit one or more data streams comprising the determined number of LTF symbols.
12. The method of claim 7 , wherein the encoding further comprises:
determining, by the wireless communication device, the number of data streams comprised in the one or more data streams is less than the number of LTF symbols comprised in the one or more LTF symbols; and
adding one or more additional LTF symbols to the one or more LTF symbols to be encoded in the one or more data streams so that a total number of LTF symbols encoded in the one or more data streams is equal to the determined number of data streams comprised in the one or more data streams, wherein the total number of LTF symbols comprises a first decodable set of LTF symbols and a second decodable set of LTF symbols, wherein one or more additional LTF symbols are added to the first decodable set using an orthogonal matrix of a first size and one or more additional LTF symbols are added to the second decodable set using an orthogonal matrix of a second size different from the first size.
13. A device, comprising:
at least one memory comprising computer-executable instructions stored thereon; and
one or more processing elements to execute the computer-executable instructions to:
determine a number of long training field (LTF) symbols comprised in one or more data streams based at least in part on a number of data streams comprised in a wireless communication channel;
encode one or more LTF symbols, in a time and/or frequency domain, into the one or more data streams of the wireless communication channel, wherein the encoding is performed using an orthogonal matrix, wherein dimensions of the orthogonal matrix are determined by the number of data streams and the number of LTF symbols; and
cause to transmit the one or more data streams comprising the one or more encoded LTF symbols over the wireless communication channel.
14. The device of claim 13 , wherein the device is further configured to:
determine a number of LTF symbols comprised in the one or more data streams based on a number of data streams determined to be comprised in the wireless communication channel.
15. The device of claim 14 , wherein the wireless communication channel comprises one or more subbands, and wherein each subband is configured to transmit one or more data streams comprising the determined number of LTF symbols.
16. A computer-readable non-transitory storage medium that contains computer-executable instructions, which when executed by one or more processors result in performing operations comprising:
determining, by a wireless communication device, a number of long training field (LTF) symbols comprised in one or more data streams based at least in part on a number of data streams comprised in a wireless communication channel;
encoding, by the wireless communication device, the one or more LTF symbols in a time and/or frequency domain into the one or more data streams of the wireless communication channel, wherein the encoding is performed using an orthogonal matrix, wherein dimensions of the orthogonal matrix are determined by the number of data streams and the number of LTF symbols; and
causing to transmit, by the wireless communication device, the one or more data streams comprising the one or more encoded LTF symbols over the wireless communication channel.
17. The medium of claim 16 , wherein the operations further comprise:
determining a number of LTF symbols comprised in the one or more data streams based on an indication from a multiuser receiver device.
18. The medium of claim 16 , wherein the wireless communication channel comprises one or more subbands, and wherein each subband is configured to transmit one or more data streams comprising the determined number of LTF symbols.