Encoding of data for transmission

A method for communicating data over a data communications network, the method comprising:

• receiving a sequence of N input blocks of bits wherein each input block comprises one of a data block and a control block, the control block being one of K types of control block and including a block-type field indicating the type of that control block;
• encoding the sequence into an output block by adding an L-bit control indicator, indicating whether the sequence contains any control blocks, as a header to the sequence, and, if the sequence contains any control blocks, producing an output block in which the order of data and control blocks in the sequence is preserved by deleting a set of bits from the block-type field of at least one control block, adding to the sequence an N-bit position indicator indicating positions of data and control blocks in the sequence, and providing in bit positions of remaining bits of the block-type field of the at least one control block an indication of the type of that control block, wherein the position indicator bits are added at bit-positions such that, in a header-first transmission order of the output block, all data and control blocks succeed the position indicator bits indicating positions of those blocks;
• transmitting the output block over the network to a receiver;
• and
• at the receiver, processing the output block in the header-first transmission order to decode the sequence of N input blocks.

A data encoding method for encoding a sequence of N input blocks of bits into an output block for transmission, wherein each input block comprises one of a data block and a control block, the control block being one of K types of control block and including a block-type field indicating the type of that control block, the method comprising sequentially processing the input blocks in the sequence to produce the output block by:

• if the sequence contains any control blocks, deleting a set of bits from the block-type field of the first control block in the sequence, and providing in bit positions of remaining bits of that block-type field an indication of the type of the first control block;
• on processing the Nth input block, adding to the sequence an L-bit control indicator indicating whether the sequence contains any control blocks;
• and
• on processing the Nth input block, if the sequence contains any control blocks, adding to the sequence an N-bit position indicator indicating positions of data and control blocks in the sequence.

A data encoding apparatus for encoding a sequence of N input blocks of bits into an output block for transmission, wherein each input block comprises one of a data block and a control block, the control block being one of K types of control block and including a block-type field indicating the type of that control block, the apparatus comprising an input buffer for receiving the sequence of input blocks, and an encoder for producing the output block from the sequence by:

• adding an L-bit control indicator, indicating whether the sequence contains any control blocks, as a header to the sequence;
• and
• if the sequence contains any control blocks, producing an output block in which the order of data and control blocks in the sequence is preserved by deleting a set of bits from the block-type field of at least one control block, adding to the sequence an N-bit position indicator indicating positions of data and control blocks in the sequence, and providing in bit positions of remaining bits of the block-type field of the at least one control block an indication of the type of that control block;
• wherein the position indicator bits are added at bit-positions such that, in a header-first transmission order of the output block, all data and control blocks succeed the position indicator bits indicating positions of those blocks.

A data encoding apparatus for encoding a sequence of N input blocks of bits into an output block for transmission, wherein each input block comprises one of a data block and a control block, the control block being one of K types of control block and including a block-type field indicating the type of that control block, the apparatus comprising an input buffer for sequentially receiving the input blocks in the sequence, and an encoder for sequentially processing the input blocks to produce the output block by:

• if the sequence contains any control blocks, deleting a set of bits from the block-type field of the first control block in the sequence, and providing in bit positions of remaining bits of that block-type field an indication of the type of the first control block;
• on processing the Nth input block, adding to the sequence an L-bit control indicator indicating whether the sequence contains any control blocks;
• and
• on processing the Nth input block, if the sequence contains any control blocks, adding to the sequence an N-bit position indicator indicating positions of data and control blocks in the sequence.