System and method for proactive repeat transmission of data over an unreliable transmission medium

• US 8,238,247 B2
• Filed: 03/25/2009
• Issued: 08/07/2012
• Est. Priority Date: 03/25/2009
• Status: Expired due to Fees

• Current Assignee: Wi-LAN Inc.
• Original Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Inventors: Wu, Shiquan, Yee, Jung
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Huang, Weibin
• Application Number:
  US12/410,807
• Publication Number:
  US 20100246472A1
• Time in Patent Office: 1,231 Days
• Field of Search: 370/229, 370/235, 370/236, 370/241, 370/248, 714/100, 714/1, 714/2, 714/15, 714/18, 714/699, 714/746, 714/748, 714/749
• US Class Current: 370/236
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

A system and method for proactive repeat transmission of data units sent using an unreliable transmission medium for the delivery of time sensitive data content predicts a future condition of a downlink data distribution channel using current channel estimation information. The predicted channel condition is used to determine which data units in a next data frame are likely to decode incorrectly, and a repeat transmission of those data units is explicitly requested by the receiving equipment, or automatically scheduled by the sending equipment using time domain channel state information provided to the sending equipment by the receiving equipment.

Claims

1. A system for proactive repeat transmission of data units sent using an unreliable transmission medium, comprising:

sending equipment adapted to receive a proactive repeat transmission request list and schedule the repeat transmission of data units specified in each proactive repeat transmission request list after data units associated with the proactive repeat transmission request list have been sent using the unreliable transmission medium; and

receiving equipment adapted to analyze data units received via a downlink channel used by the sending equipment to predict a condition of that downlink channel during a next transmission interval, and further adapted to construct the proactive repeat transmission request lists using the predicted condition, and to send a proactive repeat transmission request list to the sending equipment via an uplink channel before the data units associated with the proactive repeat transmission request list have been sent,

wherein the receiving equipment further comprises a channel estimation module that receives output from a fast Fourier transform of data units received from the sending equipment via the downlink channel and computes time domain channel state information using the fast Fourier transform output.

2. The system as claimed in claim 1 wherein the sending equipment further comprises a proactive repeat transmission scheduler that receives the proactive repeat transmission request list from an uplink channel receiver and decoder, and schedules the repeat transmission of the data units.

3. The system as claimed in claim 1 wherein the sending equipment further comprises a proactive repeat transmission and automatic repeat request (ARQ) scheduler adapted to receive the repeat transmission request list as well as automatic repeat request information from the sending equipment.

4. The system as claimed in claim 3 wherein the receiving equipment further comprises a channel prediction module that receives the time domain channel state information and computes a predicted condition of the downlink channel for each data unit to be sent during a next transmission interval to construct the proactive repeat transmission request list that is sent to the sending equipment.

5. The system as claimed in claim 4 wherein the receiving equipment further comprises a data combining and quadrature amplitude modulation (QAM) demapper that receives a copy of the repeat transmission request list and uses the repeat transmission request list to:

determine when all of the data units have been received in the next transmission interval; and

, to combine repeated data units with original data units sent by the sending equipment before the original data units are demapped by the QAM demapper.

6. A system for proactive repeat transmission of data units sent using an unreliable transmission medium, comprising:

sending equipment adapted to receive time domain channel state information and to analyze the time domain channel state information to construct a proactive repeat transmission request list; and

, further adapted to schedule the repeat transmission of data units specified in the proactive repeat transmission request list after data units associated with the proactive repeat transmission request list have been sent using the unreliable transmission medium; and

receiving equipment adapted to analyze data units received via a downlink channel used by the sending equipment to;

compute the time domain channel state information; and

, predict a condition of that downlink channel during a next transmission interval; and

further adapted to construct a corresponding proactive repeat transmission request list using the predicted condition of the downlink channel.

7. The system as claimed in claim 6 wherein the sending equipment further comprises a proactive repeat transmission scheduler that receives the proactive repeat transmission request list constructed by the sending equipment and schedules the repeat transmission of the data units.

8. The system as claimed in claim 6 wherein the sending equipment further comprises a proactive repeat transmission and automatic repeat request (ARQ) scheduler adapted to receive the repeat transmission request list constructed by the sending equipment as well as automatic repeat request information sent by the sending equipment.

9. The system as claimed in claim 6 wherein the receiving equipment further comprises a channel estimation module that receives output from a fast Fourier transform of data units received by the receiving equipment via the downlink channel, and computes the time domain channel state information using the fast Fourier transform output.

10. The system as claimed in claim 9 wherein the receiving equipment further comprises a channel prediction module that receives the time domain channel state information, sends the time domain channel state information to the sending equipment, and uses the time domain channel state information to compute a corresponding proactive repeat transmission request list.

11. The system as claimed in claim 10 wherein the receiving equipment further comprises a data combining and quadrature amplitude modulation (QAM) demapper that receives the corresponding repeat transmission request list and uses the corresponding repeat transmission request list to:

determine when all of the data units have been received in the next transmission interval; and

, to combine repeated data units with original data units sent by the sending equipment before the original data units are demapped by the QAM demapper.

12. A method of sending data units to receiving equipment using an unreliable transmission medium, comprising:

computing a predicted condition of a downlink channel, to determine which of a predetermined number of the data units to be sent are data units likely to decode incorrectly during a transmit interval when the predetermined number of the data units are to be sent, wherein computing the predicted condition of the downlink channel comprises using channel estimation information extracted from a signal received via the downlink channel by the receiving equipment to predict the condition of the downlink channel during a transmit interval when the predetermined number of data units are to be sent;

scheduling a proactive repeat transmission of the data units likely to decode incorrectly so that the proactive repeat transmission of the data units occurs after the predetermined number of data units are sent by sending equipment to the receiving equipment via the downlink channel; and

creating a proactive repeat transmission request list using the predicted condition of the downlink channel and sending the proactive repeat transmission request list to the sending equipment via an uplink channel before the predetermined number of data units are to be sent by the sending equipment.

13. The method as claimed in claim 12 wherein computing a predicted condition of the downlink channel over which the data units are to be sent comprises:

using time domain channel state information computed by the receiving equipment using information extracted from a signal received via the downlink channel and sent by the receiving equipment to the sending equipment before the predetermined number of data units are to be sent;

whereby the sending equipment predicts the condition of the downlink channel when the predetermined number of data units are to be sent using the time domain channel state information received from the receiving equipment, and uses the predicted condition of the downlink channel to compile a proactive repeat transmission list that is used to schedule the proactive repeat transmission of the data units predicted to decode incorrectly.

14. The method as claimed in claim 13 wherein a proactive repeat transmission scheduler schedules the proactive repeat transmission of the data units using the proactive repeat transmission request list compiled by the sending equipment.

15. The method as claimed in claim 12 further comprising respectively storing in a buffer of the receiving equipment each of the predetermined number of the data units as well as repeated data units;

and, combining the repeated data units with corresponding ones of the predetermined number of data units before the predetermined number of data units are decoded.

16. The method as claimed in claim 15 further comprising sending automatic repeat request (ARQ) information from the receiving equipment to the sending equipment in an event that the predetermined number of data units fail to decode correctly.

17. A method of sending high-definition television content to receiving equipment using TV white space bandwidth, comprising:

computing a predicted condition of a downlink channel over which a predetermined number of the data units are to be sent, to determine which of the predetermined number of the data units to be sent are data units likely to decode incorrectly; and

scheduling a proactive repeat transmission of the data units likely to decode incorrectly so that the proactive repeat transmission of the data units occurs after the predetermined number of data units are sent by sending equipment to the receiving equipment via the downlink channel;

wherein computing a predicted condition of the downlink channel over which the data units are to be sent comprises using time domain channel state information computed by the receiving equipment using information extracted from a signal received via the downlink channel and sent by the receiving equipment to the sending equipment before the predetermined number of data units are to be sent, whereby the sending equipment predicts the condition of the downlink channel when the predetermined number of data units are to be sent using the time domain channel state information received from the receiving equipment, and uses the predicted condition of the downlink channel to compile a proactive repeat transmission list that is used to schedule the proactive repeat transmission of the data units predicted to decode incorrectly.