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US 7099269
Added 9/23/2026, 10:37:11 AM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US 7,099,269 B2
Title: Methods and apparatus for generating and utilizing training codes in a space division multiplexing communication system
Patent number: US 7,099,269 B2
Inventor: Didier Johannes R. van Nee
Original assignee: Agere Systems LLC (later recorded as Avago Technologies International Sales Pte. Ltd.)
Key dates: Priority date 2000-11-13; filing date 2001-11-13; publication date 2006-08-29. Google Patents lists the status as "Expired – Lifetime," adjusted expiration 2024-06-08 (noted as an assumption, not a legal conclusion).
Purpose and plain-language scope:
Space division multiplexing (SDM) sends a communication signal over multiple parallel transmission paths. In a non-wired setting the transmitters interfere, so each receiver sees a mix: for two paths, r1 = h1·x1 + h2·x2 and r2 = h3·x1 + h4·x2. The system must learn the constants h before information is sent. A straightforward training scheme sends a training symbol from each transmitter in turn while the others are idle, requiring at least n training symbols for n paths — costly overhead for high-rate wireless packet links (at 100 Mbps, a 1000-byte packet lasts only 80 µs).
The invention reduces training time by having the training means generate a training code with at least nearly ideal cyclic auto-correlation properties — its cyclic auto-correlation function is nearly zero for all cyclic shifts. The transmitters send this code concurrently, mutually shifted. The receiver performs a cyclic auto-correlation on the received training signal, yielding either n·hi or zero (h i being a constant to estimate, n a known normalization factor). In theory only one training-symbol duration is needed to recover all constants.
Further disclosed aspects: the receiver may itself generate the cyclic shifts and correlate them with the received code; the code may comprise a concatenation of the rows of a Fourier matrix (Frank and Zadoff-Chu sequences, with ideal auto-correlation properties); code length preferably equals the number of connection paths or an integer multiple; dummy codes may precede and follow the training codes to avoid overlap in the auto-correlation output; and the training means may include a pre-correction filter.
Source: https://patents.google.com/patent/US7099269/en
What the excerpt does not establish: It is an excerpt, with omitted text; it does not provide the full claims, the complete description, drawing contents, or the exact per-claim scope. It does not establish validity, enforceability, ownership history in legal effect, or prior-art distinctions.
Generated 10/1/2026, 9:54:10 PM
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Prior art
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