Accounting for error carryover in error correction on M-bit encoded links
AssigneeAlcatel Lucent
InventorBijan Raahemi
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Abstract
64/66b encoding (IEEE 802.3ae Standard for 10 Gigabit Ethernet) is based on a self-synchronous scrambler which inherently duplicates errors occurring in the transmission line. An error carryover indicator ECI vector is used to correct duplicated errors crossing the codeword boundary and entering into the next codeword. The ECI vector is updated for each codeword C(i) to provide the position of the erroneous bit(s) carried over to the next codeword C(i+1). The codeword C(i+1) is corrected by XOR-ing it with the ECI vector.
Claims19
A method of correcting, at the receive side of a communication system, carryover errors generated by a self-synchronizing scrambler at the transmit side of the communication system, comprising:
- a) defining an error carryover indicator (ECI) vector and initializing said vector to a reset value;
- b) determining the position error_bit of an erroneous bit in a codeword C(i) and correcting said erroneous bit;
- c) if said error_bit is outside a first range defined between bit position 0 and said bit position R1 in said codeword C(i), updating said ECI vector to a current value;
- d) if said error_bit is in said first range, setting said current value of said ECI(i) vector to said reset value;
- e) correcting any carryover error within said codeword C(i+1) using said current value ECI(i) of said ECI vector;
- and
- f) repeating steps b-e for each codeword received at said received side, wherein N is the number of bits in a codeword.
An error control black receiver (ECB_Rx) for decoding N-bit codewords that have been scrambled at transmission using a self-synchronizing scrambler, comprising:
- means for storing M codewords;
- error computation means for detecting and correcting a single-bit error in a codeword C(i);
- a syndrome table for determining the bit position error_bit of said single-bit error;
- an error carryover indicator (ECI) generator for locating a carryover error in a next codeword C(i+1), induced by said single-bit error;
- and
- means for correcting said carryover error using said ECI vector.
Dependencies are inferred from the claim text.