Method and system for quickly finding a control channel in a private cellular system

• US 6,285,881 B1
• Filed: 09/13/1996
• Issued: 09/04/2001
• Est. Priority Date: 05/31/1996
• Status: Expired due to Fees

• Current Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Huang, Chenhong
• Primary Examiner(s): TO, DORIS HA
• Application Number:
  US08/713,383
• Time in Patent Office: 1,817 Days
• Field of Search: 455/403, 455/422, 455/434, 455/450, 455/452, 455/454, 455/455, 455/462, 455/464, 455/465, 455/515, 455/516, 455/517, 455/67.1, 455/553, 455/552, 455/161.1 , 455/179.1, 455/188.1, 455/426, 375/216, 375/260, 375/343, 375/349, 375/207, 375/340, 375/341, 375/290
• US Class Current: 455/434
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

The method of quickly locating non-standard control channels in private cellular systems is accomplished in an embodiment of the present invention by determining the modulation type of a particular channel. The mobile station scans a received RF channel. The received signal is used for the evaluation of the modulation type of that channel by using matched filters designed for the specific signal of interest, and/or in another embodiment of the present invention is used for producing the spectral energy distribution of the channel revealing the type of modulation.

Claims

1. In a radio communication system utilizing a plurality of channels, a method for identifying one of the channels as a control channel including the steps of:

accepting an input signal from one of said channels;

comparing said input signal to a predetermined baseline signal by passing said input signal through a matched filter configured to identify a predetermined characteristic of the input signal;

identifying the input signal as a control channel based on a predetermined characteristic of the comparison results;

wherein the radio communication system is a mobile radiotelephone system and the plurality of channels is divided into a plurality of voice/data channels and a plurality of control channels.

2. The method of claim 1 wherein the step of comparing further includes the step of passing the signal to a plurality of matched filters, each filter optimized to identify one of a plurality of predetermined characteristics.

3. The method of claim 2 wherein the predetermined characteristic is one of the group of FM, QPSK and FSK modulation types.

4. The method of claim 3 further including the steps of:

identifying the input signal as a control signal; and

selecting a channel identified as containing a control signal for initiating and controlling communication with a base station.

5. The method of claim 4 further including the step of:

storing the channel number so identified.

6. A method of identifying and selecting a control channel from a plurality of voice/data channels within a cellular network including a base station and a mobile unit, the method comprising the steps of:

accepting an input signal from one of said channels;

comparing said input signal to a predetermined baseline signal by passing the signal to a plurality of matched filters, each filter optimized to identify a modulation type of the input signal as one of the group of FM, FSK and QPSK modulation types;

identifying the input signal as a control channel based on said modulation type;

selecting a channel identified as containing a control signal for initiating and controlling communication with a base station; and

storing the channel number in memory.

7. A mobile unit for use in a wireless telephone system comprising:

means for receiving an input signal;

means for comparing said input signal to a predetermined baseline signal;

means for generating a comparison result including matched filter means operably connected to the input signal for identifying a predetermined characteristic of the input signal based on the comparison of the baseline and input signal;

means for identifying the input signal as a control channel based on a predetermined characteristic of the comparison result; and

means for selecting the identified control channel identified for initiating and controlling communication with a base station.

8. A mobile unit as in claim 7 further comprising means for storing the channel identifier of an identified control channel and wherein the predetermined characteristic of the input signal is of the group FM, QPSK and FSK.