Efficient multi-cast broadcasting for packet data systems

• US 20030112778A1
• Filed: 12/19/2001
• Published: 06/19/2003
• Est. Priority Date: 12/19/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lundby, Stein A.
• Granted Patent: US 6,856,604 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0006 by adapting the transmission format
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 12/1836 with heterogeneous network architecture
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
• CPC Class Codes: H04L 12/189 in combination with wireless systems selective distribution or broadcast in wireless communication networks H04W4/06
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint
• CPC Class Codes: H04W 4/08 User group management
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 72/54 based on quality criteria
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support

Abstract

Methods and apparatus are presented for efficient broadcasting in wireless packet data systems. A single MAC_ID is used for broadcasting to a group of subscribers. By using the channel quality information of the group of subscribers, a base station determines the identity of the subscriber with the worst channel conditions. The timing and the transmission format of the multi-cast are then tailored so that the subscriber with the worst channel conditions is capable of recovering the transmission. If the timing and the transmission format is chosen in relation to subscriber with the worst channel conditions, it is probable that other subscribers will be able to recover the transmission as well. Hence, only a single MAC_ID need to be used to make a single broadcast, rather than sending multiple transmissions to multiple subscribers.

Claims

1. An apparatus for multi-cast transmissions that minimize channel resources, comprising:

a memory element; and

a processing element for executing a set of instructions stored in the memory element, the set of instructions for;

generating an identifier for a group of subscribers, wherein the identifier is for accessing a multi-cast service;

using channel quality information for at least one subscriber to determine the timing of the multi-cast service to the group of subscribers; and

transmitting the identifier and the multi-cast service on at least one channel, wherein the multi-cast service is transmitted in accordance with the timing determined by the channel quality information.

2. The apparatus of claim 1, wherein transmitting the identifier and the multi-cast service on at least one channel comprises:

transmitting the identifier on a first channel; and

transmitting the multi-cast on a second channel.

3. The apparatus of claim 2, wherein the processing element is further for executing instructions for:

scrambling the multi-cast service before transmitting the multi-cast service on the second channel, wherein the scrambling is performed by using a code known only to the group of subscribers.

4. The apparatus of claim 1, wherein using channel quality information for at least one subscriber to determine the timing of the multi-cast service comprises:

choosing channel quality information by selecting the channel quality information associated with the subscribers with the worst channel conditions; and

determining the timing of the multi-cast service in accordance with the subscribers with the worst channel conditions.

5. The apparatus of claim 4, wherein the channel quality information is a measurement of the channel interference of the forward link common pilot signal.

6. The apparatus of claim 4, wherein the channel quality information is derived from the transmission power levels of a base station.

7. The apparatus of claim 4, wherein the channel quality information is a plurality of acknowledgment signals.

8. The apparatus of claim 7, wherein choosing the channel quality information of the subscribers with the worst channel conditions comprises:

transmitting a plurality of test data packets to the group of subscribers;

waiting for a plurality of acknowledgment signals from the group of subscribers in response to the plurality of test data packets; and

transmitting the multi-cast service if the plurality of acknowledgment signals indicates a response from a predetermined percentage of the group of subscribers.

9. The apparatus of claim 1, wherein using channel quality information for at least one subscriber to determine the timing of the multi-cast service comprises:

choosing the channel quality information of the subscriber with the worst channel conditions;

determining the timing of the multi-cast service in accordance with the subscriber with the worst channel condition.

10. The apparatus of claim 9, wherein the channel quality information is an acknowledgment signal from the subscriber with the worst channel condition.

11. An apparatus for multi-cast transmissions that minimize channel resources, comprising:

a memory element; and

a processing element for executing a set of instructions stored in the memory element, the set of instructions for;

generating an identifier for a group of subscribers, wherein the identifier is for accessing a multi-cast service;

using channel quality information for at least one subscriber to determine the transmission format of the multi-cast service to the group of subscribers; and

transmitting the identifier and the multi-cast service on at least one channel, wherein the multi-cast service is transmitted in accordance with the transmission format determined by the channel quality information.

12. The apparatus of claim 11, wherein transmitting the identifier and the multi-cast service on at least one channel comprises:

transmitting the identifier on a first channel; and

transmitting the multi-cast on a second channel.

13. The apparatus of claim 12, wherein the processing element is further for executing instructions for:

scrambling the multi-cast service before transmitting the multi-cast service on the second channel, wherein the scrambling is performed by using a code known only to the group of subscribers.

14. The apparatus of claim 11, wherein using channel quality information for at least one subscriber to determine the transmission format of the multi-cast service comprises:

choosing channel quality information by selecting the channel quality information associated with the subscribers with the worst channel conditions; and

determining the transmission format of the multi-cast service in accordance with the subscribers with the worst channel conditions.

15. The apparatus of claim 14, wherein the channel quality information is a measurement of the channel interference of the forward link common pilot signal.

16. The apparatus of claim 14, wherein the channel quality information is derived from the transmission power levels of a base station.

17. The apparatus of claim 14, wherein the channel quality information is a plurality of acknowledgment signals.

18. The apparatus of claim 17, wherein choosing the channel quality information of the subscribers with the worst channel conditions comprises:

transmitting a plurality of test data packets to the group of subscribers;

waiting for a plurality of acknowledgment signals from the group of subscribers in response to the plurality of test data packets; and

transmitting the multi-cast service if the plurality of acknowledgment signals indicates a response from a predetermined percentage of the group of subscribers.

19. The apparatus of claim 11, wherein using channel quality information for at least one subscriber to determine the transmission format of the multi-cast service comprises:

choosing the channel quality information of the subscriber with the worst channel conditions;

determining the transmission format of the multi-cast service in accordance with the subscriber with the worst channel condition.

20. The apparatus of claim 19, wherein the channel quality information is an acknowledgment signal from the subscriber with the worst channel condition.

21. An apparatus for multi-cast transmissions that minimize channel resources, comprising:

a memory element; and

a processing element for executing a set of instructions stored in the memory element, the set of instructions for;

determining the channel quality information for a plurality of subscribers;

identifying the subscriber with the worst channel conditions;

scrambling a multi-cast service using a scrambling code known to the plurality of subscribers; and

transmitting the scrambled multi-cast service to the plurality of subscribers, wherein the scrambled multi-cast service is transmitted in accordance with a transmission format that is optimal for the subscriber with the worst channel conditions.

22. A method for broadcasting to a group of subscribers in a cellular communication network, comprising:

determining the channel quality information for a plurality of subscribers;

identifying the subscriber with the worst channel conditions;

scrambling a multi-cast service using a scrambling code known to the plurality of subscribers; and

transmitting the scrambled multi-cast service to the plurality of subscribers, wherein the scrambled multi-cast service is transmitted in accordance with a transmission format that is optimal for the subscriber with the worst channel conditions.

23. A method for broadcasting to a group of subscribers in a cellular communication network, comprising:

generating an identifier for a group of subscribers, wherein the identifier is for accessing a multi-cast service;

using channel quality information for at least one subscriber to determine the timing of the multi-cast service to the group of subscribers; and

transmitting the identifier and the multi-cast service on at least one channel, wherein the multi-cast service is transmitted in accordance with the timing determined by the channel quality information.

24. A method for broadcasting to a group of subscribers in a cellular communication network, comprising:

generating an identifier for a group of subscribers, wherein the identifier is for accessing a multi-cast service;

using channel quality information for at least one subscriber to determine the transmission format of the multi-cast service to the group of subscribers; and

transmitting the identifier and the multi-cast service on at least one channel, wherein the multi-cast service is transmitted in accordance with the transmission format determined by the channel quality information.

25. A method for efficient multi-cast broadcasting, comprising:

generating an identifier for a group of subscribers, wherein the identifier is for accessing a multi-cast service;

identifying the subscriber with the worst channel quality by analyzing a plurality of channel quality feedback indicators from a group of subscribers;

selecting a timing and a transmission format of the multi-cast service so that the multi-cast service will be received by the subscriber with the worst channel conditions; and

transmitting the identifier on a first channel and the multi-cast service on a second channel in accordance with the timing and the transmission format as determined by the subscriber with the worst channel quality.