Tower discovery and failover

• US 7,043,214 B2
• Filed: 12/11/2002
• Issued: 05/09/2006
• Est. Priority Date: 12/11/2002
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Thompson, R. Donald III, Corbea, Cosmin A.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US10/317,737
• Publication Number:
  US 20040116068A1
• Time in Patent Office: 1,245 Days
• Field of Search: 455/185.1, 455/186.1, 455/45, 455/161.1, 455/2, 455/166.1, 455/179.1, 455/3.01, 455 303- 305, 340 746- 48
• US Class Current: 455/185.1
• CPC Class Codes: H03J 1/0058 provided with channel identification means arrangements for monitoring the use made of broadcast services H04H60/31
• CPC Class Codes: H04H 20/57 for mobile receivers
• CPC Class Codes: H04H 60/41 for identifying broadcast space, i.e. broadcast channels, broadcast stations or broadcast areas
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service
• CPC Class Codes: H04W 84/022 One-way selective calling networks, e.g. wide area paging

Abstract

Described is a communication system including wireless client devices. In the described system, the client devices may be wrist-worn watches such as are in common use today, except that the watches are specially configured to receive transmissions from broadcast towers. A client device is associated with one or more home service regions, and is configured to receive personal messages on a home channel when in the home service region. The client device employs a self-assignment method to identify and select a home channel without the need for interaction by a user. A tower discovery method is employed to identify broadcast towers and available channels within a service region. A failover method is employed to identify a change in the broadcast system, and take appropriate action such as, for example, changing to another broadcast tower, selecting another frequency, selecting a sleep mode, as well as others.

Claims

1. A method for a client device to maintain communications with a broadcast tower within a service region, comprising:

initializing the client device to a receiver channel, further comprising;

initiating a frequency sweep;

selecting a frequency during the frequency sweep;

tuning a receiver to the selected frequency;

receiving frames over a sample-interval with the receiver;

storing the received frames over the sample-interval;

analyzing the received frames;

locking the selected frequency when the received frames identify a valid signal;

selecting another frequency when the received frames indicate an invalid signal;

retrieving a station list when the selected frequency is locked;

selecting a home station from the station list by;

computing a unique code, wherein the unique code is associated with the client device;

determining a home station as station number=N modulo n, wherein N corresponds to at least a portion of the unique code, and n corresponds to the number of stations in the service region; and

selecting the home station for reception; and

receiving messages from the receiver, wherein the receiver is tuned to the locked frequency, wherein the received messages are associated with the home station.

2. The method of claim 1, wherein the frequency sweep corresponds to one of a linear sweep, a logarithmic sweep, a sweep of frequencies in predetermined steps, and selecting frequencies from a table of predetermined frequencies.

3. The method of claim 1, wherein the frequency sweep ranges over the FM broadcast spectrum.

4. The method of claim 1, wherein the frequency sweep ranges between 88 Mhz and 107 MHz in 100 kHz increments.

5. The method of claim 1, wherein analyzing the received frames comprises correlating the stored frames, and identifying the valid signal when the correlation identifies frames that are assigned to a service region that matches the client device home service region.

6. The method of claim 1, further comprising assigning the current service region as the client home service region when the client home service region was previously unassigned, wherein the current service region is identified from the received frames.

7. The method of claim 1, further comprising:

manually assigning the current service region by user selection.

8. The method of claim 1, further comprising identifying a control message from the received frames that includes an assignment of the home service region, and assigning a service region to the client home service region in response to the control message.

9. The method of claim 1, further comprising:

identifying a change control message from the received messages, wherein the control messages indicates that a change has occurred in the system;

receiving a new station list after the change control message; and

selecting the home station from the new station list, wherein the change in the system includes;

an old broadcast tower has gone off-line, a new broadcast tower is brought on-line, and a system reset is initiated.

10. The method of claim 1, wherein selecting a home station further comprises:

computing a unique code, wherein the unique code is associated with the client device;

determining an assigned tower from the unique code; and

selecting the assigned tower for reception.

11. The method of claim 1, wherein N corresponds to a 32-bit number from a 128-bit unique code.

12. The method of claim 1, wherein computing the unique code comprises:

selecting a unique identifier that is associated with the client device, applying the unique identifier as a seed to a code generator that provides a resulting code, and determining the unique code from the resulting code and an encryption string.

13. The method of claim 1, wherein initialization further restarting the initialization when no valid signal is identified within the frequency sweep.

14. The method of claim 1, wherein initialization further restarting the initialization a maximum number of reties when no valid signal is identified within the frequency sweep.

15. The method of claim 1, wherein initializing further comprises increasing the sample size when no valid signal is identified in the frequency sweep.

16. The method of claim 15, wherein initializing further comprises terminating the initialization when no valid signal is identified in the frequency sweep and the sample size is a maximum size.