US 5619492

Patent Overview — US 5,619,492 A

Title: CDMA communication system in which bit rates are dynamically allocated

Patent number / application: US 5,619,492 A; application US 08/491,033

Inventors: Harry B. Press; Thomas R. Giallorenzi; Mark T. Rafter

Assignee: Unisys Corporation (original assignee and current assignee as listed)

Key dates: Priority/filing date 1995-06-16 (application filed by Unisys); publication/grant date 1997-04-08; anticipated expiration 2015-06-16. Legal status listed as "Expired – Fee Related." The source notes legal status is an assumption, not a legal conclusion.

Purpose: The patent addresses drawbacks in multipoint-to-point CDMA systems — specifically, buffer overload at transmitting stations and exceeding total network bit-rate capacity when many stations transmit — by dynamically allocating bit rates.

Plain-language scope: A CDMA system has multiple transmitting stations and one receiving station coupled over a CDMA channel and a feedback channel. Each transmitting station sends control signals at spaced time intervals requesting bit rates; the receiving station's bit-rate allocating circuit responds with feedback messages addressed to individual stations, granting bit rates. Each station receives messages bearing its address and transmits CDMA data at the granted rate. A transmitting station may include a data buffer holding a time-varying number of bytes and request rates based on that number. Stations encode data using a spreading code at a fixed chips-per-second rate and a selectable chips-per-bit count corresponding to the granted rate. The allocating circuit tallies granted bit rates and keeps the tally below a predetermined maximum aggregate bit rate. The specification notes one embodiment uses a pre-existing coaxial cable in a cable television network, with transmitting stations in houses and the receiving station at the cable plant. Figures include formats for CDMA signals and feedback messages, station circuit diagrams, a bit-rate allocation program, and a rate-change timing diagram.

Source: https://patents.google.com/patent/US5619492/en

What the excerpt does not establish: The excerpt omits the full description and all claims, so exact claim language, claim count, and specific numerical limits are not established. It does not establish figures or reference numerals, the specific allocation program logic, detailed circuit implementations, or the precise CDMA signal/feedback message formats. It also does not establish examination history, cited references, or the accuracy of the listed legal status, expiration, or assignee data.