US 5856971

US5856971A — Patent Overview

Title: "Code division multiple access system providing variable data rate access to a user"

Patent number: US5856971A (application US08/504,481)

Assignee: AT&T Inc (original and current assignee per the source listing)

Inventors: Richard Dennis Gitlin; Chih-Lin I

Dates (as listed in the source):

• Prior art date: 1994-05-13 (noted in the source as an assumption, not a legal conclusion)
• Filing date: 1995-07-20
• Publication/grant date: 1999-01-05
• Anticipated expiration: 2014-05-13; legal status listed as "Expired - Lifetime"

Purpose. The patent relates to code division multiple access (CDMA) systems and, more particularly, to a CDMA system giving a user variable and dynamic bandwidth capacity access. In CDMA, a unique binary spreading sequence (code) is assigned per call per user; the user's signal is spread onto a channel wider than the user signal, with the ratio termed the spreading gain, and all active users share the same system channel bandwidth simultaneously.

Plain-language scope. The disclosed multi-code CDMA system lets a radio transmitter unit dynamically change its source data rate. An adjustable coding means spreads and transmits the user's digital information, received at a selected bit rate, to a channel bit rate at least equal to the highest of a plurality of source bit rates. Those source bit rates include a basic bit rate R and at least one bit rate that is an integer multiple M of R, where M is at least 1; the user's input selects a rate by identifying the multiple M to a receiving base station. The excerpt describes three transmitter embodiments (FIGS. 2–4) and a flow chart (FIG. 5) for dynamically changing the source data bit transmission rate, and notes a prior-art arrangement using a fixed number of multiple transmitters/receivers with different spreading codes (citing Wi-LAN Inc. Technical Bulletin No. 3, October 1993, "Multicode Direct Sequence Spread Spectrum").

Source: https://patents.google.com/patent/[US5856971](/patent/US5856971)/en

What the excerpt does not establish: It does not provide full claim text, the complete specification, or omitted portions; it does not establish claim scope, validity, enforceability, or legal status conclusively (the source itself labels legal-status and priority-date information as assumptions). It also does not establish any litigation, ownership transfers, or additional prior art beyond the single Wi-LAN reference mentioned.