Extremely high throughput trigger based (EHTTB) legacy preamble puncturing for fine timing and frequency offset estimation

A method comprising:

• determining that a quantity of client devices within a plurality of client devices exceed a number of available sub-channels;
• determining, for each of the plurality of client devices, in response to determining that the quantity of client devices within the plurality of client devices exceed the number of available sub-channels, a respective corresponding plurality of distances the plurality of client devices are away from an Access Point (AP);
• placing the plurality of client devices into a plurality of clusters based on the respective corresponding plurality of distances the plurality of client devices are away from the AP;
• allocating, within a user information field of a trigger frame, a legacy preamble puncturing pattern to each of the plurality of client devices wherein each of the plurality of clusters is allocated with at least one respective corresponding non-overlapping sub-channel;
• receiving, from each of the plurality of client devices on their respective corresponding non-overlapping sub-channel, a respective corresponding preamble;
• and
• performing time and frequency synchronization on a cluster-by-cluster basis for each of the plurality of client devices based on their respective corresponding preamble.

A system comprising:

• a memory storage;
• and
• a processing unit coupled to the memory storage, wherein the processing unit is operative to:
• allocate, within a user information field of a trigger frame, a legacy preamble puncturing pattern to each of a plurality of client devices wherein each of the plurality of client devices is allocated with at least one respective corresponding non-overlapping sub-channel;
• receive, from each of the plurality of client devices on their respective corresponding non-overlapping sub-channel, a respective corresponding preamble;
• and
• perform time and frequency synchronization for each of the plurality of client devices based on their respective corresponding preamble wherein the processing unit being operative to perform time and frequency synchronization comprises the processing unit being operative to perform a fine timing and Carrier Frequency Offset (CFO) estimation wherein the processing unit being operative to perform the fine timing and CFO estimation comprises the processing unit being operative to use cross-correlation based techniques using a Legacy Long Training Field (L-LTF).