US 5345597

Patent Overview: US5345597A

Title: Call set-up in a radio communication system with dynamic channel allocation
Patent number: US5345597A
Application number: US08/040,395
Inventors: Leo Strawczynski; Howard M. Sandler; Gregory L. Plett; David G. Steer
Original assignee: Northern Telecom Ltd
Current assignee (per listed data): Rockstar Bidco LP
Priority date: 1990-10-17 | Filing date: 1993-03-30 | Publication/grant date: 1994-09-06
Legal status (as listed): Expired – Lifetime; anticipated expiration 2011-09-06
Source: https://patents.google.com/patent/[US5345597](/patent/US5345597)/en

Purpose
The invention addresses call set-up in radio systems using dynamic channel allocation (DCA), especially cellular systems, where each cell may potentially use any traffic channel and the channel choice is made dynamically and in a decentralized manner by the base station or subscriber terminal. The stated problem is that a channel may appear free of interference at one end of the link (e.g., the base station) but suffer appreciable interference at the other end (e.g., the subscriber terminal), degrading link quality. Existing approaches, such as U.S. Pat. No. 4,628,152 (Akerberg), rely on channel information from only one end and require radio signalling channels.

Plain-language scope
A base station scans available traffic channels and compiles a list of channels that are useable/low-interference from its perspective, then forwards that list to the subscriber terminal over a signalling channel. The subscriber terminal scans the listed candidates, selects channels that are also low-interference from its perspective, and reports its choices back over a signalling channel. The reported choices include the channel with the lowest interference level and the channel with the second lowest level, in that order; the call proceeds on the lowest-interference channel. The second channel is noted as useful for hand-over, per a co-pending application. Signalling/traffic channels may use time-division duplex ("ping-pong"). The patent also describes a corresponding system for selecting a traffic channel to complete call set-up. Figures cover a system illustration, a frequency plan, base station/subscriber block diagrams, and call set-up flow diagrams.

What the excerpt does not establish
Only the front-matter, classification, definitions, and partial description were supplied. The full claim set, detailed embodiments, complete references, and the co-pending applications (Ser. No. 568,148; the hand-over application) are not reproduced. Nothing here establishes validity, enforceability, litigation history, or the accuracy of listed assignees and legal status.