A Method to Extend Orthogonal Latin Square Codes

Abstract

Error correction codes (ECCs) are commonly used to protect memories from errors. As multibit errors become more frequent, single error correction codes are not enough and more advanced ECCs are needed. The use of advanced ECCs in memories is, however, limited by their decoding complexity. In this context, one-step majority logic decodable (OS-MLD) codes are an interesting option as the decoding is simple and can be implemented with low delay. Orthogonal Latin squares (OLS) codes are OS-MLD and have been recently considered to protect caches and memories. The main advantage of OLS codes is that they provide a wide range of choices for the block size and the error correction capabilities. In this brief, a method to extend OLS codes is presented. The proposed method enables the extension of the data block size that can be protected with a given number of parity bits thus reducing the overhead. The extended codes are also OS-MLD and have a similar decoding complexity to that of the original OLS codes. The proposed codes have been implemented to evaluate the circuit area and delay needed for different block sizes.

Error Correction Codes Derived from Orthogonal Latin Square Codes

“…Syndrome bits thus calculated are connected to majority logic and correction module. To detect / correct a data bit di, syndrome bits having the same di as one of its input, are given to the OS-MLD gate [1] [6]. Inputs of OS-MLD correction logic for data bit d0 are shown in Fig.5.…”

“…However it requires more number of parity bits compared to other ECC"s. With increase in number of error correction bits, parity bits increase rapidly. Research is being done to reduce the parity bits and a method has been proposed recently [6]. In this paper different advancements in OLS-MLD codes are present.…”

Extend orthogonal Latin square codes for 32-bit data protection in memory applications

“…Authors in [20] have proposed a method based on the properties mentioned above to extend OLS codes. They use the same number of parity bits as the original OLS codes but providing the same correction capability for a larger number of data bits.…”

“…The proposed scheme uses the method in [20] which satisfies the constructions of OLS codes and the principles of the OS-MLD decoding algorithm that was discussed above for constructing a code that fits 32-bit data. Seven columns that correspond to data bits and three rows that correspond to parity bits are added to the H matrix for (45, 25) OLS code that is shown in Fig.…”

“…In some application, this disadvantage can be offset by flexibility and simple and fast decoding implementation. In addition, some enhancements have been proposed in order to extend the number of data bits by using the same number of parity bits, which increase the rate of a code [20]. However, for a typical memory word length of 32-bit, there are no OLS codes that can be directly used.…”