US Patent No. 9,075,738

EFFICIENT LDPC CODES


Patent No. 9,075,738
Issue Date July 07, 2015
Title Efficient Ldpc Codes
Inventorship Micha Anholt, Tel Aviv (IL)
Naftali Sommer, Rishon Lezion (IL)
Tal Inbar, Hod-Hasharon (IL)
Assignee Apple Inc., Cupertino, CA (US)

Claim of US Patent No. 9,075,738

6. A method, comprising:
initializing a decoder with a first Error Correction Code (ECC), wherein the first ECC is defined by a first set of parity
equations;

receiving a plurality of input code words, wherein each input code word of the plurality of input code words is encoded with
a second ECC, wherein the second ECC is defined by a second set of parity equations, wherein the second set of parity equations
is a proper subset of the first set of parity equations;

receiving an indication of which parity equations are included in the first set of parity equations but excluded from the
second set of parity equations;

and
decoding, iteratively, each input code word of the received plurality of input code words based upon messages transferred
between the symbol node memory and the check node memory, wherein the messages transferred between the symbol node memory
and the check node memory are controlled such that messages originating from check nodes that correspond to parity check equations
excluded from the second set of parity equations are prevented from affecting the symbol nodes by assigning to symbol nodes
respective artificial confidence metrics that indicate a zero value with a maximal likelihood based upon the received indication
of the parity equations included in the first set of parity equations but excluded from the second set of parity equations.