US 11212146

Patent Overview — US11212146B2

Title: "Header repetition in packet-based OFDM systems"
Inventor(s): Joon Bae Kim; Marcos C. Tzannes
Current assignee (as listed): AX Wireless LLC
Application number: US17/136,801 | Filed: 2020-12-29 | Granted/Published: 2021-12-28
Priority date (as listed, an assumption per the source): 2009-08-21 | Anticipated expiration (as listed): 2030-08-20
Status (as listed): Active
Source: https://patents.google.com/patent/[US11212146](/patent/US11212146)/en

Purpose and plain-language scope (from the supplied text only):
The disclosure concerns communications systems—specifically packet-based OFDM systems (also referencing IEEE 802.11, IEEE 802.16, ITU G.9960/G.hn, and DMT). A packet is described as comprising a preamble, header, and payload. Because the header carries control information needed to decode the payload and to determine packet length for virtual carrier sensing, reliably decoding the header is described as essential.

The described techniques involve repeating header information—transmitting multiple OFDM symbols carrying header information, with a repetition count denoted "D" (a maximum denoted D_MAX, and H_MAX, which "can be 2 or larger than 2"). The text notes that fixed D=1 yields differing decodability across bandplans due to differing frequency diversity, while fixed D=2 may help narrowband devices but add unnecessary overhead for wideband devices.

Described aspects include: a transmitter selecting/determining at least one D value; a receiver starting with one OFDM header symbol and, on decode failure, attempting to decode two, and so on, with each additional symbol providing diversity; communicating D (or D_MAX) in a header or MAP frame so nodes need not know D a priori; a domain master selecting fixed or dynamic D values for nodes; and per-TXOP D selection. A "Header Ext" label is noted as possibly containing different header information than "Header," and the payload may be omitted in some cases (e.g., ACK, RTS/CTS). Copied blocks are described as copies, though the copied block's modulation "may not be exactly the same."

What the excerpt does not establish: It provides only definitions and summary passages—no claim language, no full specification, no figures, and no prior-art citations are included. It therefore does not establish the actual claimed scope, the written description's full support for any feature, or validity. All legal-status, assignee, and date entries are expressly labeled in the source as assumptions, not legal conclusions. The excerpt also does not identify which aspects, if any, are claimed versus merely described.