Dynamic configuration of a flexible orthogonal frequency division multiplexing PHY transport data frame
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.
1. A method comprising:
generating, by a processor, a frame comprising a payload portion and a non-payload portion, the payload portion of the frame including a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols, each OFDM symbol having a useful portion and a cyclic prefix;
dividing, by the processor, the payload portion of the frame into at least one partition;
calculating, by the processor, a sum of a number of samples in the payload portion of the frame and a number of samples in the non-payload portion of the frame;
computing, by the processor, a number of excess samples based at least in part on a difference between a total number of samples assigned to the frame and the calculated sum;
increasing a cyclic prefix size of each OFDM symbol in the payload portion of the frame based at least in part on the computed number of excess samples; and
transmitting the frame.
2. The method of claim 1 , wherein increasing the cyclic prefix size of each OFDM symbol in the payload portion of the frame comprises:
increasing a first cyclic prefix size of said each OFDM symbol in a first partition of the payload portion of the frame by a first number of samples;
increasing a second cyclic prefix size of said each OFDM symbol in a second partition of the payload portion of the frame by a second number of samples;
wherein the first number of samples is different than the second number of samples.
3. The method of claim 2 , further comprising setting the second number of samples to zero.
4. The method of claim 2 , wherein the first number of samples and the second number of samples are determined according to an algorithm known to a remote computing device configured to receive the frame.
5. The method of claim 1 , wherein the cyclic prefix satisfies a size constraint based on a corresponding minimum guard interval duration.
6. The method of claim 1 , wherein one of the at least one partition of the payload portion of the frame represents an initial contiguous subset of the OFDM symbols in the payload portion of the frame.
7. The method of claim 1 , further comprising embedding signaling information in the frame.
8. The method of claim 1 , further comprising interleaving the plurality of OFDM symbols in the payload portion of the frame to form OFDM symbol clusters.