Patent ID: 6868519

Claim:
Apparatus for transmitting a transmission payload data bit-stream through an optical free-space medium, said apparatus comprising: means for encoding an optical transmission payload data bit-stream into codewords using Reed-Solomon encoding; means for fragmenting said codewords into sequences of segments; a buffer store comprising SDRAM devices for storing physical pages, each said SDRAM device having a cycle rate including a READ rate and a WRITE rate, said SDRAM device being both readable and writable at said cycle rate, and each said SDRAM device matrix of memory cells having a defined repeating x-y row-column submatrix, each for containing a single one of said physical pages; means for interleaving successive blocks of codeword segments into successive said x-y submatrices in WRITE operations having a first page-change overhead operation; means for READING out codeword segments from said x-y submatrices in READ operations having a second page-change overhead operation, to create an encoded and interleaved data-bit stream; means for addressing said WRITE and said READ operations into and out of said submatrices to substantially redistribute said first page-change overhead operation to said second page-change overhead operation, thereby to equalize the rate of said WRITE and said READ operations; and means for transmitting said encoded and interleaved data-bit stream into said optical free space medium.