Error Rate Constraint Research Articles

Energy-Efficient Transponder Configuration for FMF-Based Elastic Optical Networks

We propose an energy-efficient procedure for transponder configuration in few-mode fiber-based elastic optical networks in which bit error rate and physical constraints are guaranteed and joint optimization of temporal, spectral, and spatial resources are addressed. We use geometric convexification techniques to provide convex formulations for the signal-to-interference plus noise ratio, transponder power consumption, and transponder configuration problem. Simulation results demonstrate that the proposed convex formulation for the transponder configuration problem is considerably faster than its mixed-integer nonlinear counterpart. We consider transmit optical power as a configurable transponder parameter and show its optimization reduces total transponder power consumption more than 20%. We also analyze the impact of mode coupling and number of available modes on power consumption of different transponder elements.

Performance analysis of cross layer design with imperfect channel information in distributed antenna systems

In this paper, based on the imperfect channel state information (CSI), a cross layer design (CLD) scheme is developed for distributed antenna system (DAS) by combining adaptive modulation (AM) at the physical layer and automatic repeat request (ARQ) at the data link layer. The performance of DAS with CLD is investigated over composite fading channel which considers large-scale path loss and small-scale Rayleigh fading. With the performance analysis, the probability density function of the estimated signal-to-noise ratio (SNR) is derived, and then, the switching thresholds under a target packet error rate constraint are further derived. According to these results, and using numerical calculation, the closed form analytical expressions of average packet error rate and spectrum efficiency of DAS with CLD are, respectively, achieved, which will provide better evaluation way for the DAS performance. To decrease the performance loss caused by the conventional single estimation in the presence of imperfect CSI, the multi-estimation method is proposed to increase the system performance by exploiting previous channel estimation information. Numerical results corroborate our theoretical analysis, and the simulation is in consistence with the theoretical result. Moreover, the system performance can be increased by decreasing the estimation error and/or path loss. Especially, the multi-estimation method can enhance the performance effectively and enable the system to tolerate large estimation errors.

A New Dynamic Transmission-Mode Selection Scheme for AMC/HARQ-Based Wireless Networks

In this paper, we study the cross-layer design for the AMC/HARQ-based wireless networks, and propose a new dynamic transmission-mode selection scheme to improve system spectrum efficiency. In the proposed scheme, dynamic thresholds for transmission-mode selection in each packet transmission and retransmission are jointly designed under the constraint of the overall packet error rate. Comparing with the existing schemes, the proposed scheme is inclined to apply higher modulation order at the first several (re)transmissions, which corresponds to higher-rate transmission modes thus higher average system spectrum efficiency. We also extend the cross-layer design to MIMO (Multi-input Multi-output) communication scenarios. Numerical results show that the proposed new dynamic transmission-mode selection scheme generally achieves higher average spectrum efficiency than the conventional and existing cross-layer design.

Dynamic User Grouping and Joint Resource Allocation With Multi-Cell Cooperation for Uplink Virtual MIMO Systems

This paper proposes a novel joint resource allocation algorithm combining dynamic user grouping, multi-cell cooperation, and resource block (RB) allocation for single carrier-frequency division multiple access uplink in multi-cell virtual MIMO systems. We first develop the dynamic multi-cell user grouping criteria using minimum mean square error equalization and adaptive modulation with bit error rate (BER) constraint. Then, we formulate and solve a new throughput maximization problem whose resource allocation includes cell selection, dynamic user grouping, and RB pattern assignment. Furthermore, to reduce the computational complexity significantly, especially in the case of large numbers of users and RBs, we present an efficient iterative Hungarian algorithm based on user and resource partitions to solve the problem by decomposing the large scale problem into a series of small scale sub-problems, which can obtain close-to-optimal solution with much lower complexity. The simulation results show that our proposed joint resource allocation algorithm with dynamic multi-cell user grouping scheme achieves better system throughput with BER guarantee than fixed user grouping algorithm and other proposed schemes in the literature.

Variable rate and power M‐QAM for DPS/DPB CoMP with adaptive modulation

AbstractDynamic point selection/dynamic point blanking (DPS/DPB)–based coordinated multipoint (CoMP) has attracted lots of interest because of the significant performance improvement with a particular low complexity. In this paper, we first investigate the average spectral efficiency (ASE) of M‐ary quadrature amplitude modulation (M‐QAM) satisfying instantaneous bit error rate constraint for DPS/DPB CoMP system with 3 different adaptive modulation strategies. Closed‐form expressions of the ASE for continuous‐rate M‐QAM are obtained in which calculus of variations is used to obtain the optimal power allocation policy. We also analyze the ASE for discrete‐rate M‐QAM which is more useful for the practical DPS/DPB CoMP wireless communication systems. Average bit error rate for DPS/DPB CoMP discrete‐rate M‐QAM is also investigated in this paper. Monte Carlo simulations are used to verify the correctness of our analysis. The results reveal that in M‐QAM DPS/DPB CoMP systems, when the channel condition is unfavorable, the transmit power is the crucial parameter to enhance the ASE, otherwise the transmit rate is the key parameter. We can also notice that by using adaptive modulation, DPS/DPB CoMP has an obvious channel capacity improvement compared to the case without coordination among different transmission points.

Three-Dimensional Adaptive Modulation and Coding for DDO-OFDM Transmission System

We propose a 3-D adaptive loading algorithm (ALA), which can individually allocate proper modulation formats, power levels, and the forward error correction codes to each orthogonal frequency division multiplexing (OFDM) subcarrier according to the estimated channel state information (CSI). The introduced look-up table operation can reduce the iterations and improve the convergence speed. To evaluate the performance of the proposed algorithm, we tailor the system parameters of direct detection optical OFDM (DDO-OFDM) to investigate the difference of effective data rate (EDR) between fixed schemes and proposed adaptive modulation and coding (AMC) schemes. When the fiber length is set to 90 km and received optical power (ROP) is −10 dBm in simulation, the AMC scheme achieves 7.86 Gb/s EDR, which is 1.93 times of the maximum EDR the fixed schemes can achieve under the bit error rate (BER) constraint. Compared with the Levin−Campello algorithm, the 3-D ALA improves about 3% and 6% data rates in poor and good CSI, respectively. In experiments, when the fiber length and ROP are 50 km and −18 dBm, respectively, the AMC scheme achieves the EDR of 4.96 Gb/s, which is 2.84 times of the maximum EDR of the fixed schemes under the BER constraint.

Capacity Analysis of Joint Transmission CoMP With Adaptive Modulation

Joint transmission (JT)-based Coordinated Multipoint (CoMP) systems achieve high performance gains by allowing full coordination among multiple cells, transforming unwanted intercell interference into useful signal power. In this paper, we present an analytical model to perform adaptive modulation for a typical JT CoMP system, consisting of three transmission points, under a target bit error rate (BER) constraint. Probability density functions of the signal-to-interference-plus-noise ratio (SINR) are derived for different JT CoMP schemes, and based on them, closed-form expressions for the average spectral efficiency (ASE) are obtained when adopting continuous-rate adaptive modulation. The study of ASE is also extended for the case of discrete-rate modulations, where the performance comparison of different practical quantized modulation schemes is carried out.

Performance Analysis of an Adaptive Incremental Cooperative Relaying Scheme for Wireless Relay Networks

In wireless relaying networks, the traditional incremental cooperative relaying scheme (IR) could improve the system throughput enormously over fading channels by exploiting relay nodes to retransmit the source data packet to the destination. In order to enhance the system throughput over time-varying fading channels, this paper proposes an adaptive incremental cooperative re-laying scheme (AIR) based on adaptive modulation and coding, which implements adaptive rate transmission for the source and relay nodes according to channel state information. We derive expressions for the AIR system throughput, and then give a gradient-based search algorithm to find the optimized adaptive solution for the AIR system by maximizing throughput subject to the constraint of packet error rate at the data link layer. The results indicate that throughput of AIR system outperforms that of traditional IR system greatly for any SNR value.

Sink-based cross-layer routing for image delivery in wireless sensor networks

With the advent of wireless technology, various applications in traditional wired networks have been adopted in wireless networks. To transmit multimedia in wireless networks, it is required to balance the power control and lifetime with the quality constraints. In this paper, we develop cross-layer mechanism based on power and modulation rate control for a multi-path routing protocol subject to total end-to-end quality level specified in terms of packet error rate and time constraint. The proposed sink-based maximal minimal residual energy (MMRE) AOMDV algorithm uses the information such as image size, node gain, noise, time constraint and residual energy of the nodes available in the route request packets to calculate the optimal power and rate vectors and the number of packets that can be sent by the source on each disjoint path to the sink. The source is freed from the complex algorithmic executions and hence the energy is conserved.

Single-Event Performance of Sense-Amplifier Based Flip-Flop Design in a 16-nm Bulk FinFET CMOS Process

The increasing need for high-speed logic circuits is causing the conventional flip-flop (FF) designs to migrate to differential FF designs. With the small magnitude of input voltages (and the resulting small noise margins) needed for proper operation, sense-amplifier based FF designs (SAFF) are susceptible to single-event effects (SEE). Single event upset (SEU) performance of high-speed SAFF designs is investigated in this paper for 16-nm bulk FinFET CMOS technology. SEU cross-sections for SAFF are evaluated over particle LET, temperature, and operating frequency. Results show significant increases in cross-sections as a function of frequency, but not so for temperature. Results presented in this work can guide designers to harden the SAFF that satisfies their specific circuit SEU error rate constraints.

An Adaptive Subcarrier Sharing Scheme for OFDM-Based Cooperative Cognitive Radios

Incorporation of orthogonal frequency division multiplexing (OFDM) in cooperative cognitive radio network facilitates subcarrier sharing to achieve spatial diversity with opportunistic spectrum access. In addition, adaptive modulation has been adopted widely in wireless communication to improve spectral efficiency. Use of adaptive modulation for cooperative cognitive relaying transmission to maximize throughput under bit error rate (BER) constraint is an open issue. In this paper, we propose an adaptive subcarrier sharing scheme for OFDM-based cooperative cognitive radio system, wherein cognitive (secondary) system helps the primary system to achieve its target rate of communication in exchange for opportunistic spectrum sharing. Secondary transmitter uses adaptive mode of transmission to relay the primary signal with higher throughput while maintaining the BER constraint of primary system. At primary receiver, a BER-based selection combining scheme is employed to combine the signals received in two phases. Closed-form analytical expressions for BER and outage probability of primary and secondary system for a Rayleigh flat fading channel have been derived. Results show that the outage probability with the proposed scheme (for dissimilar modulation) outperforms direct transmission and conventional maximal ratio combining scheme (for similar modulation).

Flash Memories: ISPP Renewal Theory and Flash Design Tradeoffs

In the write process of multilevel per cell (MLC) flash memories, an iterative approach is used to mitigate the monotonicity problem. The monotonicity in programming is considered to be the major restriction in MLC flash. To solve this issue, an iterative approach called incremental step pulse programming (ISPP) is used to concurrently program lots of cells in small steps. In this paper, we are mostly concerned with deriving a mathematical model for iterative programming using the framework of renewal theory . We obtain a closed-form approximation for the probability distribution of the number of steps required in the ISPP process. We also bound the maximal error between the true distribution and our approximation. Moreover, the results obtained help to accurately analyze the effect of inter-cell interference in this type of memory. Finally, we devise an adaptive step size approach for write process to strike a balance between latency and lifetime under fixed bit error rate constraints or information rate constraints.

Multi-User Sum-Rate Optimization for Visible Light Communications With Lighting Constraints

In visible light communication (VLC) systems, white light emitting diodes (LEDs) are used as illumination sources and transmitters simultaneously. Compared to the phosphor-converted LEDs, multi-chip LEDs have higher modulation bandwidth. Consequently, the multi-chip based VLC systems have great potential for high data rate transmission. Since each chip of the multi-chip LEDs can be modulated independently, parallel communication channels are viable for information transmission. In this paper, in order to maximize the multi-user sum-rate for the multi-chip based multi-input single-output VLC systems, an electrical and optical power allocation scheme is proposed in consideration of the luminance, chromaticity, amplitude and bit error rate constraints. From the perspective of human color vision, the chromaticity constraint is defined within a MacAdam ellipse. As a result, the degree of freedom can be achieved by relaxing the chromaticity constraint from a fixed color point to an elliptic region. Numerical results demonstrate that with the increase of the total luminous flux, the maximum sum-rates present an open-down parabolic tendency due to the limited dynamic range of LEDs. Higher data rate can be achieved under higher correlated color temperature (CCT) for the variation of light components. In addition, the simulation results indicate that the shapes of the chromaticity constrained region (either ellipse or quadrangle) have little impact on the multi-user sum-rate at the same CCT.

Multi-device task offloading with time-constraints for energy efficiency in mobile cloud computing

Nowadays, in order to deal with the increasingly complex applications on mobile devices, mobile cloud offloading techniques have been studied extensively to meet the ever-increasing energy requirements. In this study, an offloading decision method is investigated to minimize the energy consumption of mobile device with an acceptable time delay and communication quality. In general, mobile devices can execute a sequence of tasks in parallel. In the proposed offloading decision method, only parts of the tasks are offloaded for task characteristics to save the energy of multi-devices. The issue of the offloading decision is formulated as an NP-hard 0–1 nonlinear integer programming problem with time deadline and transmission error rate constraints. Through decision-variable relaxation from the integer to the real domain, this problem can be transformed as a continuous convex optimization. Based on Lagrange duality and the Karush–Kuhn–Tucker condition, a solution with coupled terms is derived to determine the priority of tasks for offloading. Then, an iterative decoupling algorithm with high efficiency is proposed to obtain near-optimal offloading decisions for energy saving. Simulation results demonstrate that considerable energy can be saved via the proposed method in various mobile cloud scenarios.

RF Power Gating: A Low-Power Technique for Adaptive Radios

In this paper, we propose a low-power technique, called RF power gating, which consists in varying the active time ratio (ATR) of the RF front end at a symbol time scale. This technique is especially well suited to adapt the power consumption of the receiver to the performance needs without changing its architecture. The effect of this technique on the bit error rate (BER) performances is studied for a basic estimator in the specific case of minimum-shift keying signaling. A system-level energy model is also derived and discussed to estimate precisely the power reduction based on the characteristics and the power consumption of each block. This model allows highlighting the different contributors of the power reduction. The BER results and the energy model are finally merged to determine the best ATR meeting the design constraints. Applying this technique to the IEEE 802.15.4 standard, this paper shows that an ATR of 20% is a good tradeoff to meet the packet error rate constraint while maximizing the energy reduction ratio. Using typical block power consumptions, an energy reduction ratio around 20% can be reached. Even better energy reduction ratios ( $\sim 60$ %) are also achievable when most of the blocks are power-gated.

Fuzzy-Based Optimized QoS-Constrained Resource Allocation in a Heterogeneous Wireless Network

A new joint scheduling and link adaptation scheme is designed using fuzzy logic. A unified scheduler is designed which provides different throughput requirements and optimally allocates the shared media to the users based on their importance. Adaptive modulation, coding, and transmit power is used provisioning an average power constraint depending on each user’s power supply. Various bit error rate and QoS-delay constraints are provided for all links. Numerical evaluations show that the proposed fuzzy-based scheme has the performance quite close to the analytical approach, however, with substantially lower complexity.

Energy-efficient resource allocation for multiuser OFDMA system based on hybrid genetic simulated annealing

Orthogonal frequency division multiple access (OFDMA) is adopted in 4G wireless communication standard, where bandwidth resources can be split into smaller granular units. Tailored for slow adaptive OFDMA system, we study the energy-efficient resource allocation problem based on chance-constrained programming. The optimization objective is to minimize the power consumption over subcarrier and power allocation. The constraints include the outage probability constraint and target bit error rate (BER) constraint. Because the optimization problem contains the probabilistic constraint, it is a chance-constrained programming problem. Hence, support vector machine (SVM) is adopted to compute the outage probability constraint. Then, we integrate SVM and genetic simulated annealing (GSA) to develop hybrid genetic simulated annealing (HGSA). Simulation tests verify that HGSA not only has the lower consumption power, but also satisfies the outage probability constraint.

Resource allocation based on cross-layer QoS-guaranteed scheduling for multi-service multi-user MIMO–OFDMA systems

Cross-layer strategies for resource allocation in wireless networks are essential to guaranty an efficient utilization of the scarce resource. In this paper, we present an efficient radio resource allocation scheme based on PHY/MAC cross layer design and QoS-guaranteed scheduling for multi-user (MU), multi-service (MS), multi-input multi-output (MIMO) concept, orthogonal frequency division multiple access (OFDMA) systems. It is about a downlink multimedia transmission chain in which the available resources as power and bandwidth, are dynamically allocated according to the system parameters. Among these parameters, we can mention the physical link elements such as channel state information, spectral efficiency and error code corrector rate, and MAC link variables, which correspond to the users QoS requirements and the queue status. Primarily, we use a jointly method which parametrizes these system parameters, according to the total power, and the bit error rate constraints. Secondly, we propose a QoS-guaranteed scheduling that shares the sub-carriers to the users. These users request several type of traffic under throughput threshold constraints. The main objective in this work is to adjust the average throughput per service of each user, according to their needs and likewise to satisfy a great number of connexions. Subsequently, we consider a model of moderated compartmentalization between various classes of services by partitioning the total bandwidth into several parts. Each class of service will occupy a part of the bandwidth and will be transmitted over a maximum number of sub-carriers. The simulation results show that the proposed strategy provides a more interesting performance improvement (in terms of average data rate and user satisfaction) than other existing resource allocation schemes, such as nonadaptive resource allocation strategy. The performances are also analyzed and compared for the two multi-service multi-user MIMO---OFDMA systems; with sub-carriers partitioning and without sub-carriers partitioning.

RS-LDPC Concatenated Coding for the Modern Tape Storage Channel

In modern tape storage, user data are recorded and retrieved along multiple tracks of rapidly moving, flexible magnetic medium that give rise to a variety of channel impediments including occasional long erasures, more frequent amplitude fades as well as a large amount of random errors. This work considers reliable recovery of data from such tape channels using a novel concatenation of an inner Reed-Solomon (RS) code and an outer nonbinary low-density parity-check (LDPC) code. This particular concatenation scheme and a highly tailored iterative decoding algorithm are chosen to efficiently handle the assortment of the tape channel impediments while meeting the stringent target error rate constraint as well as key practical requirements of the mass tape storage system. Despite the use of a nonbinary LDPC code, the proposed scheme allows excellent performance-complexity tradeoffs. In stark contrast to any existing coding schemes that involve LDPC codes, the proposed concatenation strategy allows semianalytic error rate performance evaluation at rates below what is possible using modern computers, thus providing an ability to ensure satisfactory low-error-rate performance.

Conventional and modified TAS/OSTBC schemes in dual‐hop fixed‐gain amplify‐and‐forward relaying systems with imperfect feedback

AbstractModified transmit antenna selection (TAS)/orthogonal space‐time block coding (OSTBC) (M‐TAS/OSTBC) schemes have been shown to achieve superior error performance together with a reduced‐rate feedback channel in the presence of feedback errors (FEs) when compared with the conventional TAS/OSTBC (C‐TAS/OSTBC) schemes. This paper focuses on the bringing of fixed‐gain amplify‐and‐forward (FGAF) relaying schemes that employ M‐TAS/OSTBC schemes at both hops that provides reduced feedback‐rate and robust error performance in the presence of erroneous‐feedback channels. The exact expressions of the outage and error probabilities for both dual‐hop FGAF relaying schemes in Nakagami‐m fading channels have been derived and validated via Monte Carlo simulations. Additionally, with the help of high signal‐to‐noise ratio (SNR) (i.e., asymptotic) approaches and some analytical approximations, the asymptotic diversity order analysis has been carried out. Besides, by providing a simulation‐based examination on the inclusion of power allocation within the modified scheme, the additional advantages on the performance have been exhibited. The extensive investigation and comparisons to the conventional schemes have shown that M‐TAS/OSTBC schemes employed at each transmission link provide full diversity order and considerable error performance as the C‐TAS/OSTBC scheme in ideal feedback cases and also achieve more robust error performance in the presence of FEs. Thus, by using M‐TAS/OSTBC schemes, the overall performances of the dual‐hop FGAF relaying schemes have been enhanced, which would result in reductions on the average SNR requirements to achieve a specified error rate constraint. Copyright © 2015 John Wiley & Sons, Ltd.