Mobile edge computing (MEC) provides computational services at the of networks by offloading tasks from user equipments (UEs). This letter employs an unmanned aerial vehicle (UAV) as server to execute offloaded ground UEs. We jointly optimize association, UAV trajectory, and uploading power each UE maximize sum bits all UEs UAV, subject energy constraint quality service (QoS) UE. To address non-convex optimization problem, we first decompose it into three subproblems that are solved with...

We propose coding techniques that simultaneously limit the length of homopolymers runs, ensure GC-content constraint, and are capable correcting a single edit error in strands nucleotides DNA-based data storage systems. In particular, for given <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> , ∈ > 0, we simple efficient encoders/decoders transform binary sequences into DNA base (codewords), namely symbols A, T, C G, satisfy all following...

This letter studies a basic wireless caching network, where source server is connected to cache-enabled base station (BS) that serves multiple requesting users. A critical problem how improve cache hit rate under dynamic content popularity. To solve this problem, the primary contribution of develop novel update strategy with aid deep reinforcement learning. Considering BS unaware popularities, proposed dynamically updates according time-varying requests and cached contents. Toward end, we...

We propose a coding method to transform binary sequences into DNA base (codewords), namely of the symbols A, T, C, and G, that satisfy following two properties: 1) run-length constraint: maximum each symbol in codeword is at most three 2) GC-content close 0.5, say between 0.4 0.6. The proposed scheme motivated by problem designing codes for DNA-based data storage systems, where digital stored synthetic sequences. Existing literature either achieve code rates not greater than 1.78 bits per...

The multi-level-cell (MLC) NAND flash channel exhibits nonstationary behavior over increasing program and erase (PE) cycles data retention time. In this paper, an optimization scheme for adjusting the read (quantized) write (verify) voltage levels to adapt is presented. Using a model-based approach represent channel, incorporating programming noise, random telegraph noise (RTN), cell-to-cell interference as major signal degradation components, write-voltage are optimized by minimizing error...

We consider coding techniques that limit the lengths of homopolymer runs in strands nucleotides used DNA-based mass data storage systems. compute maximum number user bits can be stored per nucleotide when a runlength constraint is imposed. describe simple and efficient implementations avoid occurrence long homopolymers, rates constructed codes are close to theoretical maximum. The proposed sequence replacement method for k-constrained q-ary yields significant improvement redundancy than...

We describe properties and constructions of constraint-based codes for DNA-based data storage which account the maximum repetition length AT/GC balance. Generating functions approximations are presented computing number sequences with balance constraint. routines translating binary runlength limited and/or balanced strings into DNA strands, compute efficiency such routines. Expressions redundancy that both derived.

An indel refers to a single insertion or deletion, while an edit insertion, deletion substitution. In this article, we investigate codes that correct either and provide linear-time algorithms encode binary messages into these of length n. Over the quaternary alphabet, two encoders. One corrects with ⌈log n⌉+ O(loglog n) redundancy bits, other n⌉+2 redundant bits. These encoders are order-optimal. The former encoder is first known order-optimal edit, latter (that indel) reduces best...

The NAND flash memory channel is corrupted by different types of noises, such as the data retention noise and wear-out noise, which lead to unknown offset make non-stationary. In literature, machine learning-based methods have been proposed for detection channels. However, these require a large number training samples labels achieve satisfactory performance, costly. Furthermore, with offset, it may be impossible obtain enough correct labels. this paper, we reformulate transfer learning (TL)...

The central problem in sequence reconstruction is to find the minimum number of distinct channel outputs required uniquely reconstruct transmitted sequence. According Levenshtein's work 2001, this determined by maximum size intersection between error balls any two input sequences channel. In work, we study for single-deletion single-substitution channel, assuming that belongs a $q$-ary code with Hamming distance at least $2$, where $q\geq 2$ fixed integer. Specifically, prove $d\geq 2$,...

In this paper, we construct q-ary codes for correcting a burst of at most t deletions, where t,q≥2 are arbitrarily fixed positive integers. We consider two scenarios error correction: the classical codes, which recover each codeword from one read (channel output), and reconstruction allow to multiple channel reads. For first scenario, our construction has redundancy logn+8loglogn+o(loglogn) bits, encoding complexity O(q7tn(logn)3) decoding O(nlogn). can codewords with reads...

Composite DNA is a recent novel method to increase the information capacity of DNA-based data storage above theoretical limit 2 bits/symbol. In this method, every composite symbol does not store single nucleotide but mixture four nucleotides in predetermined ratio. By using different mixtures and ratios, alphabet can be extended have much more than symbols naive approach. While enables higher content per synthesis cycle, potentially reducing cost, it also imposes significant challenges for...

The multi-level-cell (MLC) NAND flash memory exhibits a diversity of the raw bit error rate (BER) over different program/erase (P/E) cycles and types bits within cell. In this letter, we first apply protograph-based extrinsic information transfer chart analysis to MLC channel design novel rate-adaptive protograph low-density parity-check (RAP-LDPC) codes by using code extension approach. proposed RAP-LDPC has multiple rates, which can be adapted dynamically P/E cycles. To mitigate unbalanced...

We consider construction of deletion and substitution correcting codes with low redundancy efficient encoding/ decoding. First, by simplifying the method Sima <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al</i> . (ISIT 2020), we construct a family binary single-deletion <inline-formula xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$s$ </tex-math></inline-formula> -substitution notation="LaTeX">$(s+1) (2s+1)\log...

Accurate modeling and estimation of the threshold voltages flash memory can facilitate efficient design channel codes detectors. However, most models are based on Gaussian distributions, which fail to capture certain key properties voltages, such as their heavy-tails. To enhance model accuracy, we first propose a piecewise student's t-distribution mixture (PSTMM), features degrees freedom control left right tails voltage distributions. We further an PSTMM expectation maximization (PSTMM-EM)...

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In this paper, we first propose a simple but general analytical channel model for bit-patterned media (BPM) systems. It facilitates the generation of accurate readback signals with large amount noise, as well design equalizer and partial response (PR) target. We further an approach to jointly two-dimensional (2-D) one-dimensional (1-D) PR target BPM systems according minimum mean square error...

Spin-torque transfer magnetic random access memory (STT-MRAM) is a promising non-volatile technology widely considered to replace dynamic (DRAM). However, there still exist critical technical challenges be tackled. For example, process variation and thermal fluctuation may lead both write errors read errors, severely affecting the reliability of array. In this paper, we first propose novel cascaded channel model for STT-MRAM that facilitates fast error rate simulations more importantly...

By accommodating overlapping transmissions over non-orthogonal resources, multiple access (NOMA) integrated with massive multiple-input multiple-output (MIMO) can boost spectral efficiency and obtain vast diversity for wireless multiuser systems. However, NOMA requires channel state information (CSI) at the receiver coherent detection, resulting in unaffordable complexity estimation as number of users goes large. Add to that, introduction MIMO makes even more challenging. In this letter, we...

The practical NAND flash memory suffers from various non-stationary noises that are difficult to be predicted. For example, the data retention noise induced channel offset is unknown during readback process, and hence severely affects reliability of recovery cell. In this paper, we first propose a novel recurrent neural network (RNN)-based detector effectively detect stored in multi-level-cell (MLC) without prior knowledge channel. However, compared with conventional threshold detector,...

The sequence reconstruction problem, introduced by Levenshtein in 2001, considers a communication scenario where the sender transmits codeword from some codebook and receiver obtains multiple noisy reads of codeword. common setup assumes to be entire space problem is determine minimum number distinct that required reconstruct transmitted Motivated modern storage devices, we study variant <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML"...

In this paper, optimization of low-density parity-check (LDPC) codes to approach the symmetric information rate (SIR) two-dimensional (2-D) intersymbol interference (ISI) channels is proposed for high-density magnetic recording, such as bit-patterned recording (BPMR) and 2-D (TDMR). The code design makes use modified Extrinsic Information Transfer (EXIT) chart, where optimal variable node degree searched by selecting best check fit decoder (CND) EXIT curve (VND) combined with detector....

In this letter, a novel scheduling scheme for decoding irregular low-density parity-check (LDPC) code, based on the column weight of variable nodes in code graph, is introduced. scheme, LDPC decoded using shuffled belief-propagation (BP) algorithm by selecting descending order their weight. Via numerical simulation, it shown that proposed high-to-low column-weight schedule can noticeably increase convergence speed at medium to high signal-to-noise ratio (SNR) over AWGN and Rayleigh fading...