Anxiao's research while affiliated with Texas A&M University and other places

Publications (5)

Article
Full-text available
The current flash memory technology focuses on the cost minimization of its static storage capacity. However, the resulting approach supports a relatively small number of program-erase cycles. This technology is effective for consumer devices (e.g., smartphones and cameras) where the number of program-erase cycles is small. However, it is not econo...
Article
Full-text available
This paper presents a practical writing/reading scheme in nonvolatile memories, called balanced modulation, for minimizing the asymmetric component of errors. The main idea is to encode data using a balanced error-correcting code. When reading information from a block, it adjusts the reading threshold such that the resulting word is also balanced o...
Article
Full-text available
The construction of asymmetric error correcting codes is a topic that was studied extensively, however, the existing approach for code construction assumes that every codeword should tolerate $t$ asymmetric errors. Our main observation is that in contrast to symmetric errors, asymmetric errors are content dependent. For example, in Z-channels, the...
Article
Full-text available
Rank modulation has been recently proposed as a scheme for storing information in flash memories. While rank modulation has advantages in improving write speed and endurance, the current encoding approach is based on the "push to the top" operation that is not efficient in the general case. We propose a new encoding procedure where a cell level is...
Article
Full-text available
Flash memory is well-known for its inherent asymmetry: the flash-cell charge levels are easy to increase but are hard to decrease. In a general rewriting model, the stored data changes its value with certain patterns. The patterns of data updates are determined by the data structure and the application, and are independent of the constraints impose...

Citations

... Researchers have also proposed some innovative data representation schemes with different requirements in terms of read thresholds. For example, rank modulation [17], [18], [19], [20], [21] stores information in the relative voltages between the cells instead of using pre-defined voltage levels. The strategy of writing data represented by rank modulation in parallel to flash memories is studied in [22]. ...
... However, the application of permutation codes and multipermutation codes for use in non-volatile memory storage systems such as flash memory has received attention in the coding theory literature in recent years [1], [12], [13], [17], [21], [22]. One of the main distance metrics in the literature has been the Kendall-τ metric, which is suitable for correction of the type of error expected to occur in flash memory devices [5], [11], [12], [13], [23]. Errors occur in these devices when the electric cell charges storing information leak over time or there is an overshoot of charge level in the rewriting process. ...
... The detector resilience to unknown mismatch by drift can be improved in various ways, for example, by employing coding techniques. Balanced codes [6,7,8,9] and composition check codes [10,11], in conjunction with Slepian's optimal detection [12] offer excellent resilience in the face of channel mismatch on a block of symbols basis. These coding and signal processing techniques are often considered too expensive in terms of code redundancy and hardware, in particular when high-speed applications are considered. ...
... Note that this model also includes the so-called Z-channel where q = 0 such that only 1 → 0 errors occur. The Z-channel captures the fact that in applications q is often significantly smaller than p [14,53]. ...
... ℓ-covering sets are useful in designing codes to flash storage related design, including correct limitedmagnitude errors [8,9,10], design memory application for flash storage [7]. Since we can compress a segment by dividing everything by its slope, algorithm where the running time depends on the size of the numbers in the input can be cut down. ...