Tower discovery and failover

• US 20070060084A1
• Filed: 03/09/2006
• Published: 03/15/2007
• Est. Priority Date: 12/11/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Corbea, Cosmin, Thompson, R.
• Granted Patent: US 7,403,754 B2
• Time in Patent Office: Days
• US Class Current: 455/185.100
• 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 communicate with a broadcast tower within a service region, the method 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 utilizing a unique code that is associated with the client device; 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 the 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 selecting a home station further comprises:

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

determining a home station from the unique code; and

selecting the home station for reception.

12. The method of claim 11, wherein determining a home station from the unique code comprises determining a station number 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.

13. The method of claim 12, wherein N corresponds to a 32-bit number from a 128-bit unique code.

14. The method of claim 11, 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.

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.

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

18. 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.

19. A method for a client device to communicate with at least one broadcast tower within a service region, the method comprising:

during a service activation;

allocating a home frequency; and

allocating a home service region;

after the service activation;

identifying a valid broadcast channel for the client device, comprising;

initiating a frequency sweep;

selecting a station frequency during the frequency sweep;

tuning a receiver to the selected station frequency;

receiving frames over a sample-interval with the receiver;

storing the received frames over the sample-interval;

analyzing the stored frames to determine a validity status associated with the stored frames;

locking the selected station frequency when the stored frames identify a valid signal; and

selecting another station frequency when the stored frames indicate an invalid signal;

after a valid broadcast channel is identified;

extracting the assigned home frequency from the stored frames;

extracting the assigned home service region from the stored frames; and

assigning the home frequency and home service region to the client device.

20. The method of claim 19, further comprising retrieving a broadcast tower list associated with the service region from the stored frames after a valid broadcast channel is identified.

21. The method of claim 19, wherein extracting the assigned home frequency from the stored frames comprises:

applying a unique identifier associated with the client device to a code generator to identify a decryption code, and decrypting the assigned home frequency from the stored frames with the identified decryption code.

22. The method of claim 19, wherein extracting the assigned home service region from the stored frames comprises:

applying a unique identifier associated with the client device to a code generator to identify a decryption code, and decrypting the assigned home frequency from the stored frames with the identified decryption code.

23. The method of claim 19, wherein extracting the assigned home frequency from the stored frames comprises:

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

determining the home frequency from the unique code by;

identifying a station number 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.

24. The method of claim 19, further comprising assigning a broadcast tower to the client device by:

retrieving a broadcast tower list associated with the service region from the stored frames after a valid broadcast channel is identified;

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

identifying the assigned broadcast tower for the client device as an offset relative to the retrieved broadcast tower list, wherein the offset is determined by offset=N modulo n, wherein “

N”

corresponds to at least a portion of the computed unique code, and “

n”

corresponds to the number of stations in the service region, wherein N corresponds to the number of broadcast towers that are available in the service region.

25. The method of claim 19, wherein tuning the receiver to the selected station frequency, further comprises tuning the receiver for reception according to at least one of a frequency modulated (FM) transmission, and a sub-carrier based frequency modulated transmission.

26. The method of claim 19, wherein analyzing the stored frames to determine the validity status associated with the stored frames further comprises:

identifying a data sync pattern in the frame such that a correlation of the data sync pattern by the client device indicates a valid signal reception by the client device.

27. The method of claim 26, wherein the data sync pattern is encoded with a unique identifier that is associated with the client device.

28. The method of claim 26, wherein the data sync pattern is encoded in a distributed manner over several segments of the transmission.

29. The method of claim 19, the received frames comprising:

a frame header and a message payload.

30. The method of claim 29, wherein information is encoded in the frame header, wherein the encoded information includes at least one of a station list, a broadcast tower list, and a control message.

31. The method of claim 29, wherein the frame header is encoded control information to identify at least one of:

a broadcast condition associated with the service region for the broadcast tower, a change in available channels associated with the service region for the broadcast tower, an assignment of a particular channel for the client device, an assignment of another particular channel for all client devices, and a change counter that is arranged to indicate when a change has taken place in the system.

32. The method of claim 19, further comprising:

receiving a transmission from a valid broadcast channel;

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

decoding a personal message for the client device from the stored frames using the computed unique code.

33. A client device that is arranged in communication with at least one broadcast tower, the client device comprising:

a means for scheduling reception on the client device;

a means for tuning a receiver in the client device to a selected station;

a means for receiving a transmission frame with the client device when scheduled for reception, wherein the transmission frame includes a frame header and a message payload;

a means for storing the received transmission frame;

a means for analyzing that is arranged to determine a validity status associated with the stored transmission frame;

a means for changing the selected station when the validity status is determined as invalid;

a means for extracting a station list from the frame header when the validity status is determined as valid;

a means for selecting a home station from the station list, wherein the home station is automatically assigned by the client device utilizing a unique code that is associated with the client device; and

a means for changing the default for the selected station to the home station; and

a means for decoding a personal message from the stored transmission frame, wherein the stored transmission frame is encoded with an encryption key that is determined from the unique code that is identified with the client device.

34. The method of claim 33, further comprising a means for automatically assigning a home broadcast tower to the client device by extracting information from the frame header utilizing the unique code that is associated with the client device.