Method for efficient packet framing in a communication network
Techniques to reduce the transmission overheads in a communication system are disclosed. In an embodiment, a method described herein relates to the elimination of redundant padding to realize an integer number of FEC code-words during the FEC-encoding process of transmission as well as the reduction/elimination of redundant padding to realize an integer number of transmission symbols during the subcarrier modulation mapping process of transmitting OFDM/ACMT/DMT symbols. The techniques are described in the context of a communication system based on the MoCA specification. Furthermore, techniques for channel-profiling, channel-estimation and bandwidth request/grant signaling that facilitate the realization of the method of reduction of transmission overheads in a MoCA system are also described.
1. A method for protecting a data payload communicated between nodes over a network, the method comprising:
encoding, in a hardware processor, a first portion of the data payload into one or more first Forward Error Correction (FEC) code-words of a first size, wherein the hardware processor is operable to execute a sequence of instructions stored in a memory; and
encoding, in the hardware processor, a second portion of the data payload into a second FEC code-word of a second size, the second size being selected from a plurality of different sizes, the selection being based on the size of the second portion of the data payload,
wherein the method comprises modulating each of the one or more first FEC code words using an adaptive constellation multi-tone (ACMT) symbol of a first type and modulating the last FEC code word using an ACMT symbol of a second type, the second type of ACMT symbol being selected from a plurality of different ACMT symbol types, the selection being based on the second size.
2. The method of claim 1 , wherein the method comprises adding an FEC pad to the second portion of the data payload according to the second size and the size of the second portion of the data payload.
3. The method of claim 1 , wherein the last FEC code-word and each of the one or more first FEC code words comprise parity-bytes.
4. The method of claim 1 , wherein the plurality of different sizes comprises the first size and at least one smaller size.
5. The method of claim 1 , wherein the method comprises adding an ACMT pad to the last FEC code word.
6. The method of claim 1 , wherein the plurality of different ACMT symbol types comprises ACMT symbols having 32, 64, 128, and 256 tones.
7. The method of claim 1 , wherein the method comprises determining a signal-to-noise ratio at a tone position of the second type of ACMT symbol by interpolating a plurality of signal-to-noise ratios of the first type of ACMT symbol.
8. A system for protecting a data payload communicated between nodes over a network, the system comprising:
a memory storing a sequence of instructions; and
a Forward Error Correction (FEC) encoder operable to execute the sequence of instructions to encode a first portion of the data payload into one or more first FEC code-words of a first size and operable to encode a second portion of the data payload into a second FEC code-word of a second size, the second size being selected from a plurality of different sizes, the selection being based on the size of the second portion of the data payload,
wherein the system comprises an adaptive constellation multi-tone (ACMT) modulator operable to modulate each of the one or more first FEC code words using a symbol of a first type and operable to modulate the last FEC code word using an ACMT symbol of a second type, the second type of ACMT symbol being selected from a plurality of different ACMT symbol types, the selection being based on the second size.
9. The system of claim 8 , wherein the FEC encoder is operable to add an FEC pad to the second portion of the data payload according to the second size and the size of the second portion of the data payload.
10. The system of claim 8 , wherein the FEC encoder is operable to add parity-bytes to the last FEC code-word and each of the one or more first FEC code words.
11. The system of claim 8 , wherein the plurality of different sizes comprises the first size and at least one smaller size.
12. The system of claim 8 , wherein the ACMT modulator is operable to add an ACMT pad to the last FEC code word.
13. The system of claim 8 , wherein the plurality of different ACMT symbol types comprises ACMT symbols having 32, 64, 128, and 256 tones.
14. The system of claim 8 , wherein the system comprises a channel estimator operable to determine a signal-to-noise ratio at a tone position of the second type of ACMT symbol by interpolating a plurality of signal-to-noise ratios of the first type of ACMT symbol.