Dynamic Configuration of a Flexible Orthogonal Frequency Division Multiplexing PHY Transport Data Frame

• US 20160043830A1
• Filed: 08/07/2015
• Published: 02/11/2016
• Est. Priority Date: 08/07/2014
• Status: Active Grant

• Current Assignee: One Media LLC (Sinclair, Inc.)
• Original Assignee: One Media LLC (Sinclair, Inc.)
• Inventors: Simon, Michael J., Shelby, Kevin A., Earnshaw, Mark
• Granted Patent: US 9,866,421 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 27/26025 Numerology, i.e. varying one or more of symbol duration, subcarrier spacing, Fourier transform size, sampling rate or down-clocking allocating sub-channels of the transmission path H04L5/003
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• 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: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

A base station may generate and transmit a transport stream including a sequence of frames. A frame may include a plurality of partitions, where each partition includes a corresponding set of OFDM symbols. For each partition, the OFDM symbols in that partition may have a corresponding cyclic prefix size and a corresponding FFT size, allowing different partitions to be targeted for different collections of user devices, e.g., user devices having different expected values of maximum delay spread and/or different ranges of mobility. The base station may also dynamically re-configure the sample rate of each frame, allowing further resolution in control of subcarrier spacing. By allowing the cyclic prefixes of different OFDM symbols to have different lengths, it is feasible to construct a frame that conforms to a set payload duration and has arbitrary values of cyclic prefix size per partition and FFT size per partition. The partitions may be multiplexed in time and/or frequency.

Claims

1. A method for constructing a data frame, the method comprising the steps of:

dividing, by a processor, a frame into a plurality of partitions;

for each of the plurality of partitions, determining, by a processor, a length of an associated OFDM symbol;

calculating, by a processor, a sum of OFDM symbol lengths in a union of the OFDM symbols over the plurality of partitions;

computing, by a processor, a number of excess samples based on the calculated sum and based on a length of a payload region of the frame; and

for each OFDM symbol in the union, assigning, by a processor, the OFDM symbol to one of at least one subset of the union using at least one of the number of excess samples and an index of the OFDM symbol, and adding a number to a cyclic prefix size of each OFDM symbol in each of the at least one subset of the union, prior to embedding the OFDM symbols in the frame.

2. The method of claim 1, wherein the OFDM symbol length is based on a corresponding FFT size and a corresponding cyclic prefix size, and wherein the corresponding cyclic prefix satisfies a size constraint based on a corresponding minimum guard interval duration.

3. The method of claim 1, wherein a unique number is used for each of the at least one subset of the union.

4. The method of claim 1, further comprising the step of the computer, for one of the at least one subset of the union, setting the unique number for that subset to zero.

5. The method of claim 1, wherein one of the at least one subset of the union represents an initial contiguous subset of the OFDM symbols in the union.

6. The method of claim 1, wherein the at least one subset of the union and the unique number for each of the at least one subset of the union are determined according to an algorithm known to a remote computing device configured to receive the data frame.

7. The method of claim 1, further comprising the step of the computer embedding signaling information in the data frame.

8. The method of claim 1, further comprising the step of the computer interleaving the OFDM symbols of the partitions to form OFDM symbol clusters.

9. A system for constructing a data frame, the system comprising one or more processors, one or more non-transitory computer-readable storage devices, and computer executable program instructions stored on at least one of the one or more storage devices for execution by at least one of the one or more processors, the program instructions comprising:

instructions for constructing a plurality of partitions, wherein each of the partitions comprise a corresponding set of OFDM symbols, wherein the OFDM symbols in each partition conform to a corresponding FFT size and satisfy a corresponding minimum guard interval; and

instructions for constructing a frame by time interleaving the OFDM symbols of the partitions to form OFDM symbol clusters, wherein the OFDM symbol clusters are defined by;

a specified value of OFDM symbol cluster size for each partition; and

a specified value of OFDM symbol cluster period for each partition.

10. The system of claim 9, wherein the program instructions further comprise program instructions for

determining a length of an associated OFDM symbol for each of the plurality of partitions;

calculating a sum of OFDM symbol lengths in a union of the OFDM symbols over the plurality of partitions;

computing a number of excess samples based on the calculated sum and based on a length of a payload region of the frame; and

for each OFDM symbol in the union, assigning the OFDM symbol to one of at least one subset of the union using at least one of the number of excess samples and an index of the OFDM symbol, and adding a number to a cyclic prefix size of each OFDM symbol in each of the at least one subset of the union, prior to embedding the OFDM symbols in the frame.

11. The system of claim 9, wherein the instructions for constructing a plurality of partitions are configured to construct a first of the partitions for transmission to a mobile computing device, and to constructs a second of the partitions for transmission to fixed computing device, wherein the FFT size corresponding to the first partition is smaller than the FFT size corresponding to the second partition.

12. The system of claim 9, wherein the program instructions further comprise program instructions for embedding signaling information in the frame, wherein the signaling information indicates a specified value of the OFDM symbol cluster size for each partition and the specified value of the OFDM symbol cluster period for each partition.

13. The system of claim 9, further comprising a user device, wherein the user device comprises one or more processors, one or more non-transitory computer-readable storage devices, and computer executable instructions stored on at least one of the one or more storage devices for execution by at least one of the one or more processors, the program instructions comprising:

instructions for determining, for a particular partition to which the user device has been assigned, the corresponding specified values of OFDM symbol cluster size and OFDM symbol cluster period based on the signaling information in the frame; and

instructions for recovering the OFDM symbols belonging to the OFDM symbol clusters of the particular partition, using the corresponding specified values.

14. The system of claim 9, further comprising a transmitter configured to transmit the data frame over a wireless communication channel.

15. A computer program product for constructing a transport stream including a data frame, the computer program product comprising one or more non-transitory computer-readable storage devices having stored thereon computer executable instructions that when executed cause at least one processor to:

construct a payload region of the frame, wherein samples in the payload region correspond to a specified sample rate, wherein the specified sample rate is selected from a universe of sample rates supported by transmission circuitry of a base station, wherein first program instructions are further configured to divide the samples in the payload region into one or more partitions, wherein each of the partitions comprises a corresponding set of OFDM symbols; and

embed signaling information in the transport stream, wherein the signaling information comprises data indicative of the specified sample rate.

16. The computer program product of claim 15, wherein the first program instructions are configured to receive data indicative of the specified sample rate from an operator of a broadcast network.

17. The computer program product of claim 15, wherein the second program instructions are configured to embed the signaling information in a non-payload region of the frame.

18. The computer program product of claim 15, wherein the one or more partitions comprises a corresponding value of FFT size for OFDM symbols associated with the one or more partitions.

19. The computer program product of claim 18, wherein the first program instructions are further configured to, for each partition, select the FFT size for the partition and the specified sampling rate to define a subcarrier spacing for the partition that satisfies a specified minimum subcarrier spacing for the partition.