Method and apparatus for locating a digital control channel in a radiocommunication system

• US 5,570,467 A
• Filed: 06/07/1995
• Issued: 10/29/1996
• Est. Priority Date: 11/01/1993
• Status: Expired due to Term

• Current Assignee: Optis Wireless Technology, LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Sawyer, Francois
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Patel, Ajit
• Application Number:
  US08/473,583
• Time in Patent Office: 510 Days
• Field of Search: 370/95.1, 370/95.2, 370/95.3, 370/110.1, 340/825.08, 455/33.1, 455/33.2, 455/54.1, 455/54.2, 379/59, 379/60, 379/63, 415/34.1, 415/161.1, 415/166.2
• US Class Current: 455/515
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0046 Code rate detection or code type detection H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091
• CPC Class Codes: H04L 1/0056 Systems characterized by the type of code used H04L1/08 takes precedence
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 1/1685 the supervisory signal being transmitted in response to a specific request, e.g. to a polling signal
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 1/1803 Stop-and-wait protocols
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1848 Time-out mechanisms
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 2001/0093 : Point-to-multipoint
• CPC Class Codes: H04L 9/40 : Network security protocols
• CPC Class Codes: H04W 48/10 : using broadcasted information
• CPC Class Codes: H04W 48/16 : Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 : Selecting an access point
• CPC Class Codes: H04W 52/0212 : managed by the network, e.g. network or access point is master and terminal is slave
• CPC Class Codes: H04W 52/0245 : according to signal strength
• CPC Class Codes: H04W 68/00 : User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: H04W 68/025 : Indirect paging
• CPC Class Codes: H04W 88/02 : Terminal devices
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

A method and system for locating control channels, particularly digital control channels, are described. By grouping the channels which are candidates for carrying supervisory messages in blocks indicative of their relative likelihood for being used as control channels, a mobile station can begin its search for a control channel with channels which are most likely to actually be control channels. Placing location information on other channels allows the mobile station to be redirected to a control channel when it reads one of these other channels. Similarly, by placing information describing the location of a control channel in a message associated with handoff, a mobile station avoids the necessity of having to relocate a new control channel associated with the base station to which the mobile has been handed off.

Claims

1. A method for locating a control channel in a radiocommunication system comprising the steps of:

providing a connection between a mobile station and a base station in said radiocommunication system using a traffic channel;

sending a message when said connection is being terminated, from said base station to said mobile station which includes location information pointing to said control channel; and

tuning to said control channel, at said mobile station, using said location information received from said base station.

2. The method of claim 1, wherein said control channel is a digital control channel.

3. The method of claim 1 wherein said message is release message.

4. A radiocommunication system comprising:

a plurality of control channels over which base stations transmit and receive supervisory data;

a plurality of traffic channels over which base stations transmit and receive traffic data;

at least one mobile station which is connected to one of said base stations using one of said plurality traffic channels; and

means, in said one of said base stations, for transmitting a message over said one of said plurality of traffic channels to said at least one mobile station when said at least one mobile station is disconnecting from said one of said base stations, said message including information which points to one of said control channels.

5. The radiocommuication system of claim 4 wherein said one of said control channel is a digital control channel.

6. The radiocommuication system of claim 4 wherein said message is a release message.

7. A base station comprising:

a transmitter for transmitting supervisory data messages on a control channel and traffic messages on a plurality of traffic channels, said traffic messages including release messages; and

means for determining information included in said supervisory data messages and said traffic messages, wherein said release messages include a field pointing toward said control channel.

8. The base station of claim 7, wherein said control channel is a digital control channel.

9. A mobile station comprising:

a receiver for receiving supervisory data messages on any of a plurality of control channels and traffic messages on any of a plurality of traffic channels; and

a processing unit for extracting location information from a termination message received on one of said plurality of traffic channels which indicates a location of one of said plurality of control channels and for commanding said receiver to tune to said one of said plurality of control channels.

10. The mobile station of claim 9, wherein said one of said plurality of control channels is a digital control channel.

11. A method for disconnecting a mobile station comprising the steps of:

receiving a disconnect message over an air interface;

acquiring location information from said disconnect message which points to the location of a control channel;

disconnecting said mobile station; and

tuning to said control channel using said location information.

12. The method of claim 11, wherein said control channel is a digital channel.