Method and system for a handoff in a broadcast communication system

• US 7,254,394 B2
• Filed: 03/15/2004
• Issued: 08/07/2007
• Est. Priority Date: 08/20/2001
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tiedemann, Edward G. Jr., Wang, Jun, Chen, Tao, Sinnarajah, Ragulan, Butler, Brian K.
• Primary Examiner(s): GELIN, JEAN ALLAND
• Application Number:
  US10/801,221
• Publication Number:
  US 20040180661A1
• Time in Patent Office: 1,240 Days
• Field of Search: 455/437, 455/442, 455/435.2, 455/435.3, 455/436, 455/438, 455/439, 455/423, 455/518, 455/519, 455/522, 455/527, 455/66.11, 455/67.16, 370/331, 370/332, 370/328
• US Class Current: 455/437
• CPC Class Codes: H04W 36/0007 for multicast or broadcast services, e.g. MBMS multicast or broadcast application services H04W4/06; resource management for broadcast services H04W72/30; connection management for selective distribution or broadcast H04W76/40
• CPC Class Codes: H04W 36/0027 for a plurality of data sessions of end-to-end connections, e.g. multi-call or multi-bearer end-to-end data connections
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/304 due to measured or perceived resources with higher communication quality
• CPC Class Codes: H04W 36/362 Conditional handover
• 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 72/30 Resource management for broadcast services

Abstract

A method and system for a handoff in a broadcast communication system is disclosed. A subscriber assisted handoff is impractical in a broadcast communication system due to e.g., a high signaling load, a difficulty to synchronize the broadcast transmission. On the other hand, the small number of broadcast channels enables the subscriber station to perform the handoff autonomously. To streamline the autonomous handoff decision process, several distinct sets of pilot identifiers and rules for transitioning among the sets are defined. To fully integrate broadcast services with the services provided by the cellular telephone systems in a subscriber environment, a methods for various handoff scenarios are analyzed.

Claims

1. A subscriber station apparatus for set management in a broadcast communication system, comprising:

means for receiving a first list identifying a first set of sectors;

means for measuring a quality metric of a forward link tmnsmitted by each identified sector;

means for removing from said first list an identifier of a sector whose mess tired quality metric exceeds a first predeteimined level;

means for placing the identifier of the sector into a second list;

means for generating a third list identifying a third set of sectors identifying all sectors unlisted in the first set or the second set;

means for removing from the third set an identifier of a sector whose measured quality metric exceeds the first predetermined level; and

means for placing the identifier of the sector in the second list.

2. A subscriber station apparatus for set management in a broadcast communication system, comprising:

means for receiving a first list identifying a first set of sectors;

means for measuring a quality metric of a forward link transmitted by each sector identified in the first list;

means for removing from said first list an identifier of a sector whose measured quality metric exceeds a first predetermined level;

means for placing the identifier of the sector in a second list; and

means for generating a third list identifying a third set of sectors in accordance with said measured quality metric, comprising;

means for removing from said second list an identifier of a sector whose measured quality metric exceeds a second predetermined level; and

means for placing the identifier of the sector in the third list.

3. The subscriber station apparatus of claim 2, further comprising:

means for removing from said second list an identifier of a sector whose measured quality metric falls below the first predetermined level; and

means for placing the identifier of the sector in the first list.

4. A subscriber station apparatus for set management in a broadcast communication system, comprising:

means for receiving a first list identifying a first set of sectors;

means for measuring a quality metric of a forward link transmitted by each sector identified in the first list;

means for removing from said first list an identifier of a sector whose measured quality metric exceeds a first predetermined level;

means for placing the identifier of the sector in a second list; and

means for generating a third list identifying a third set of sectors in accordance with said measured quality metric, comprising;

means for starting a timer when an identifier of a sector is placed in the second list;

means for removing from said second list the identifier of the sector when said timer expires and the sector'"'"'s quality metric is above the second predetermined level; and

means for placing the identifier of the sector in the third list.

5. The subscriber station apparatus of claim 4, further comprising:

means for stopping the timer when the sector'"'"'s quality metric falls below the second predetermined level.

6. The subscriber station apparatus of claim 5, further comprising:

means for removing from said second list the identifier of the sector when the sector'"'"'s quality metric falls below the first predetermined level; and

means for placing the identifier of the sector in the first list.

7. An apparatus for set management in a broadcast communication system, comprising:

a receiver for receiving a first list identifying a first set of sectors;

a measuring device for measuring a quality metric of a first forward link transmitted by each identified sector;

an apparatus for removing from said first list an identifier of a sector whose measured quality metric exceeds a first predetermined level;

an apparatus for placing the identifier of the sector into a second list;

a generating apparatus for generating a third list identifying a third set of sectors identifying all sectors unlisted in the first set or the second set;

an apparatus for removing from the third set an identifier of a sector whose measured quality metric exceeds the first predetermined level; and

an apparatus for placing the identifier of the sector in the second list.

8. An apparatus for set management in a broadcast communication system, comprising:

receiver for receiving a first list identifying a first set of sectors;

a measuring device for measuring a quality metric of a forward link transmitted by each sector identified in the first list;

an apparatus for removing from said first list an identifier of a sector whose measured quality metric exceeds a first predetermined level;

an apparatus for placing the identifers of the sector in a second list;

an apparatus for generating a third list identifying a third set of sectors in accordance with said quality metric, comprising;

apparatus for removing from said second list an identifer of a sector whose measured quality metric exceeds a second predetermined level; and

apparatus for placing the identifier of the sector in the third list.

9. The apparatus of claim 8, further comprising:

an apparatus for removing from said second list an identifier of a sector whose measured quality metric falls below the first predetermined level; and

apparatus for placing the identifier of the sector in the first list.

10. An apparatus for set management in a broadcast communication system, comprising:

receiver for receiving a first list identifying a first set of sectors;

a measuring device for measuring a quality metric of a forward link transmitted by each sector identified in the first list;

an apparatus for removing from said first list an identifier of a sector whose measured quality metric exceeds a first predetermined level;

an apparatus for placing the identifier of the sector in a second list; and

a generating apparatus for generating a third list identifying a third set of sectors in accordance with said measured quality metric, comprising;

a timer initiator for starting a timer when an identifier of a sector is placed in the second list;

an apparatus for removing from said second list the identifier of the sector when said timer expires and the sector'"'"'s quality metric is above the second predetermined level; and

an apparatus for placing the identifier of the sector in the third list.

11. The apparatus of claim 10, further comprising:

a timer stopping device for stopping the timer when the sector'"'"'s quality metric falls below the second predetermined level.

12. The apparatus of claim 11, further comprising:

an apparatus for removing from said second list the identifier of the sector when the sector'"'"'s quality metric falls below the first predetermined level; and

an apparatus for placing the identifier of the sector in the first list.