# US 5,345,597 A · Call set-up in a radio communication system with dynamic channel allocation

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- Number: US 5,345,597 A
- Document ID: US5345597A
- Status: Granted
- Kind: A
- Application number: 08/040,395
- Filed: 1993-03-30
- Granted: 1994-09-06
- Earliest claimed: 1990-10-17
- Assignees: Northern Telecom Limited
- Inventors: Leo Strawczynski; Howard M. Sandler; Gregory L. Plett; David G. Steer
- Web page: https://patentgrep.com/patent/US5345597A

## CPC

- H04W 72/541: using the level of interference
- H04W 36/06: Reselecting a communication resource in the serving access point
- H04W 24/00: Supervisory, monitoring or testing arrangements
- H04W 24/10: Scheduling measurement reports {; Arrangements for measurement reports}
- H04W 52/0206: {in access points, e.g. base stations}
- H04W 72/02: Selection of wireless resources by user or terminal
- H04W 72/20: Control channels or signalling for resource management
- H04W 76/10: Connection setup
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

The call set-up technique of this invention is characterized by the use of channel information from both base station and subscriber terminal in determining the radio traffic channel upon which to set-up a new call. Communication between the base station and subscriber terminal is carried out on a signalling channel until the traffic channel is chosen. Calls are set-up so that they proceed on the radio channel which, of a set of channels under consideration by the subscriber terminal, contains the least amount of interference as measured at the subscriber terminal. The set of channels under consideration by the subscriber terminal is a subset of the entire set of channels allocated to the service. This subset is comprised of those channels having little interference, as measured by the base station. The call set-up technique thereby assures that calls proceed on channels containing little interference from the viewpoints of both base station and subscriber terminal.

## Claims

### Claim 1

In a radio communication system having a number of base stations, each communicating with a plurality of subscriber terminals over separate traffic channels and each base station having access to each of said plurality of traffic channels, a method of selecting a traffic channel for completing call set-up of incoming and outgoing calls between a base station, a subscriber terminal and the Public Switched Telephone Network (PSTN), comprising the steps of:
receiving, at said base station, an incoming call attempt from a subscriber or from the PSTN;
scanning, at said base station, said plurality of traffic channels for the presence of radio power levels above a first specified threshold;
measuring the power level of a scanned traffic channel;
selecting from the scanned traffic channels, traffic channels with radio power levels below said first specified threshold;
storing a list of selected traffic channels;
sending to the subscriber terminal, along a signalling channel linking the base station and the subscriber terminal, the list of selected traffic channels;
receiving the list at the subscriber terminal;
scanning the traffic channels on the list;
measuring the power level on each scanned traffic channel on said list;
selecting from the scanned traffic channels of the list, traffic channels with radio power levels below a second specified threshold;
storing the traffic channel selection at said subscriber terminal;
sending, to the base station, along the signalling channel, the subscriber terminal's traffic channel selection, which provides an indication of the subscriber terminal's preferred traffic channel and redundant traffic channel to be selected if the preferred traffic channel becomes unusable;
receiving the traffic channel selection at said base station;
switching the base station and the subscriber terminal to the preferred traffic channel; and
proceeding with call connection.

### Claim 2 (depends on 1)

A method as defined in claim 1, wherein of the traffic channels scanned at said base station, only a first number of sequentially scanned traffic channels having radio power levels below said first specified threshold are selected and stored in said list.

### Claim 3 (depends on 1)

A method as defined in claim 1, wherein each of said plurality traffic channels are scanned at said base station and only a first number of traffic channels having the lowest radio power levels below said first specified thresholds are selected and stored in said list.

### Claim 4 (depends on 1)

A method as defined in claim 1, wherein said plurality of traffic channels are scanned by switching said base station on an available frequency channel using frequency synthesizer means.

### Claim 5 (depends on 4)

A method as defined in claim 4, wherein said traffic channels are prescanned prior to call set-up attempt.

### Claim 6 (depends on 4)

A method as defined in claim 4, wherein said traffic channels are scanned continuously to maintain a list of useable traffic channels.

### Claim 7 (depends on 1)

A method as defined in claim 1, further comprising the step of:
selecting from the scanned traffic channels, traffic channels with radio power levels above said first specified threshold if the number of traffic channels with power levels below said first threshold in insufficient.

### Claim 8 (depends on 7)

A method as defined in claim 7, further comprising, at said subscriber terminal, the step of:
selecting from the scanned traffic channels those traffic channels having the lowest radio power levels.