Dynamic link assignment in a communication system

• US 7,230,908 B2
• Filed: 07/16/2001
• Issued: 06/12/2007
• Est. Priority Date: 07/24/2000
• Status: Expired due to Term

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Thesling, William H., Vanderaar, Mark J., Nimon, Matthew D.
• Primary Examiner(s): Pezzlo; John
• Assistant Examiner(s): Mehra; Inder Pal
• Application Number:
  US09/906,171
• Publication Number:
  US 20020018527A1
• Time in Patent Office: 2,157 Days
• Field of Search: 370/203, 370/208, 370/277, 370/280, 370/294, 370/343, 370/465, 370/468, 370/503, 370/390, 370/391, 379/133, 379/358, 375/340
• US Class Current: 370/203
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals

Abstract

An architecture for the dynamic assignment of links in a multi-user communication system. A plurality of information channels are provided in a forward communication link of the communication system for carrying channel information of the plurality of information channels from a transmitter to a plurality of corresponding receiving devices. The channel information in corresponding select ones of the plurality of information channels is varied dynamically in response to link conditions of the associated receiving devices to more efficiently utilize the channel bandwidth.

Claims

1. A method of communicating data in a multi-user communication system using orthogonal frequency division multiplexing (OFDM), comprising the steps of:

providing channel information for one or more dynamically assigned frequency channels of a plurality of frequency channels in an OFDM communication link;

receiving link information identifying link conditions for one or more devices to receive said channel information;

dynamically varying a modulation and coding format associated with said channel information in said one or more dynamically assigned frequency channels in a response to said identified link conditions;

and transmitting said channel information according to said varied modulation and coding format to said receiving devices in said dynamically assigned frequency channels using a broadcast communication signal;

wherein said channel information includes a unique ID, said unique ID for uniquely identifying each said receiving device;

wherein said unique ID is utilized to transmit said channel information in unicast to select ones of said plurality of receiving devices or in multicast to all said receiving devices.

2. The method of claim 1, wherein said plurality of frequency channels are time division multiplexed.

3. The method of claim 1, wherein said channel information in said one or more dynamically assigned frequency channels in the varying step is varied in gain and frequency in accordance with said identified link conditions.

4. The method of claim 1, wherein said channel information in said one or more of said plurality of frequency channels in the varying step is varied in modulation, coding, gain, and frequency in accordance with said identified link conditions such that synchronization of said respective information channel is maintained.

5. The method of claim 1, wherein the communication system is a satellite communication systems that transmits said channel information in said communication link that is a wireless forward communication link.

6. The method of claim 1, wherein the varying step is performed on select ones of said plurality of frequency channels utilizing time division multiplexing and orthogonal frequency division multiplexing.

7. The method of claim 1, wherein said frequency channels overlap.

8. The method of claim 1, wherein said channel information comprises data to be transmitted over a frequency channel of said plurality of frequency channels.

9. The method of claim 1, further comprising:

dynamically assigning said one or more frequency channels to said one or more receiving devices after said modulation and coding format associated with said channel information is dynamically varied.

10. A method of communicating data in a multi-user communication system using orthogonal frequency division multiplexing (OFDM), comprising the steps of:

providing channel information for one or more dynamically assigned frequency channels in a plurality of frequency channels in an OFDM communication link;

receiving link information identifying link conditions for one or more devices to receive said channel information;

varying a modulation and coding format associated with said channel information in said one or more dynamically assigned frequency channels in response to said identified link conditions;

and transmitting said channel information according to said varied modulation and coding format to said receiving devices in said dynamically assigned frequency channels using a broadcast communication signal;

wherein synchronization of carrier and timing between transmitter and said receiving devices is achieved utilizing a frequency channel of said plurality of frequency channels in said communication link.

11. The method of claim 10, wherein said frequency channel includes a plurality of information slots such that each said information slot must contain information in order to achieve said synchronization of carrier and timing.

12. An apparatus for communicating data in a multi-user communication system using orthogonal frequency division multiplexing (OFDM), comprising:

a transmitter configured to transmit data over one or more dynamically assigned frequency channels of a plurality of frequency channels in an OFDM communication link of the communication system for carrying channel information between said transmitter and one or more receiving devices;

a receiver for receiving link information identifying link conditions for at least one of said one or more receiving devices; and

a varying device coupled with said transmitter and said receiver, and configured to control said transmitter to vary a modulation and coding format associated with said channel information in said one or more dynamically assigned frequency channels in response to said identified link conditions;

wherein said channel information is transmitted according to said varied modulation and coding format with said transmitter to said one or more receiving devices in said dynamically assigned frequency channels using a broadcast communication signal;

wherein said channel information includes a unique ID, said unique ID for uniquely identifying each said receiving device;

wherein said unique ID is utilized to transmit said channel information in unicast to select ones of said plurality of receiving devices or in multicast to all said receiving devices.

13. The apparatus of claim 12, wherein said plurality of frequency channels are time division multiplexed.

14. The apparatus of claim 12, wherein said varying device varies channel information in gain and frequency in accordance with said identified link conditions.

15. The apparatus of claim 12, wherein said varying device varies channel information in modulation, coding, gain, and frequency in accordance with said identified link conditions such that synchronization of said respective information channel is maintained.

16. The apparatus of claim 12, wherein the communication system is a satellite communication system that transmits said channel information in said communication link that is a wireless forward communication link.

17. The apparatus of claim 12, wherein said varying device varies only modulation and coding in accordance with said identified link conditions of said corresponding information channel.

18. The apparatus of claim 12, wherein said varying device varies channel information on select ones of said plurality of information channels utilizing time division multiplexing and orthogonal frequency division multiplexing.

19. An apparatus for communicating data in a multi-user communication system using orthogonal frequency division multiplexing (OFDM), comprising:

a transmitter configured to transmit data over one or more dynamically assigned frequency channels of a plurality of frequency channels in an OFDM communication link of the communication system for carrying channel information between said transmitter and one or more receiving devices;

a receiver for receiving link information identifying link conditions for at least one of said one or more receiving devices; and

a varying device coupled with said transmitter and said receiver, and configured to control said transmitter to vary a modulation and coding format associated with said channel information in said one or more dynamically assigned frequency channels in response to said identified link conditions;

wherein said channel information is transmitted according to said varied modulation and coding format from said transmitter to said one or more receiving devices in said dynamically assigned frequency channels using a broadcast communication signal; and

wherein synchronization between said transmitter and said plurality of receiving devices is achieved utilizing a frequency channel of said plurality of frequency channels in said communication link.

20. The apparatus of claim 19, wherein said frequency channel includes a plurality of information slots such that each said information slot must contain information in order to achieve said synchronization, said synchronization including both carrier and timing.

21. A method for dynamically modifying a communication signal in accordance with different link conditions in a communications system, the method comprising:

associating a unique ID with a data packet to thereby identify a receiving device for said data packet;

receiving information identifying a link condition for said receiving device;

dynamically assigning a modulation and coding format for said data packet to account for said identified link condition; and

transmitting said data packet, according to said modulation and coding format, in a dynamically assigned frequency channel of a broadcast communication signal including a plurality of frequency channels formatted to carry data to particular users.

22. The method of claim 21, wherein said dynamically assigned frequency channel comprises time slots in said dynamically assigned frequency channel in an orthogonal frequency division multiplexing communication link.

23. A method for dynamically modifying an orthogonal frequency division multiplexing waveform including a plurality of frequency channels in a multi-user communications system wherein at least a subset of devices in said system receive said waveform under different link conditions, the method comprising:

associating a unique ID with information in said waveform to thereby identify a receiving device for said information;

receiving data identifying link conditions for said receiving device;

dynamically varying a modulation and coding format for said information in a dynamically assigned frequency channel of said plurality of frequency channels to adapt said dynamically assigned frequency channel to said identified link conditions for said receiving device; and

transmitting said waveform as a broadcast communication signal including said plurality of frequency channels in said multi-user communications system.

24. The method of claim 23, further comprising:

dynamically assigning said frequency channel to said receiving device after said modulation and coding format is dynamically varied.

25. The method of claim 23, wherein said dynamically assigned frequency channel comprises time slots in said dynamically assigned frequency channel.