Hybrid error control mechanism for wireless ATM based on traffic type

In comparison to Ultra-Reliable Low-Latency Communications (URLLC) in 5G mobile communication systems, the next generation URLLC (xURLLC) requires even lower latency and higher reliability. To address these requirements, we propose a novel redundancy version (RV)-adaptive hybrid automatic repeat request (HARQ) scheme. Our approach builds upon the existing 5G HARQ framework and 5G low-density parity-check (LDPC) codes, introducing an adaptive selection of the RV for the subsequent transmission based on the current decoding states. To determine the optimal RV, we use a modified version of the reciprocal channel approximation (RCA) algorithm to compare the decoding thresholds of all available RVs and select the one with the lowest threshold to maximize the likelihood of successful decoding. To further reduce processing delay, we apply a deep neural network (DNN) to predict the optimal RV for the next transmission. This prediction is made prior to the decoding process, ensuring that no additional delay is introduced. Since the selection is made before the decoding starts, our proposed method can seamlessly integrate with other adaptive-HARQ and fast HARQ schemes.

Transmission efficiency is an interesting topic for data link layer developers. The overhead of protocols and coding should be reduced to a minimum. This maximizes a link throughput. This is especially important for high-speed networks, where a small degradation of efficiency will degrade the throughput by several Gbps. We describe a redundancy balancing algorithm for an adaptive hybrid automatic repeat request with Reed-Solomon coding. We introduce a testing environment, most important technical issues, and results generated on a field programmable gate array. The hybrid automatic repeat request and Reed-Solomon algorithms are explained. We provide a mathematical description, and a block diagram of the adaptation algorithm. All necessary algorithm simplifications are explained in details. The algorithm can be represented by basic operations in hardware. In most cases, it finds the optimal coding for a predefined bit error rate.

There are two kinds of technique used for error control: FEC (forward error correction) and ARQ (automatic repeat request). Combining these two schemes, which is called HARQ (hybrid ARQ), makes it possible to increase the channel throughput. The error of the channel quality estimate that is used to select the MCS (modulation coding scheme) in type I HARQ can be a serious problem in scenarios when the mobile station moves at high speeds. Furthermore, in a system dominated by packet services, the interference level may be bursty, and thus it is difficult to predict the interference level. Therefore, the type II HARQ scheme is a more robust solution compared with type I HARQ. In order to improve channel throughput while at the same time satisfying quality of service (QoS) under various channel conditions, an efficient hybrid ARQ type II scheme is proposed. The optimum redundancy size for every transmission is calculated to maximize the throughput using QoS parameters, the performance of LDPC code and channel conditions. The proposed scheme, together with such benefits as QoS support, provides a way of achieving higher throughput in wireless communication systems.

Hybrid automatic repeat request (HARQ) is a high-performance communication protocol, leading to the effective use of the wireless channel and the resources with only limited feedback about the channel state information (CSI) to the transmitter. In this paper, the throughput of HARQ with incremental redundancy (IR) and fixed transmission rate is studied in the presence of statistical queuing constraints imposed as limitations on buffer overflow probabilities. In particular, tools from the theory of renewal processes and stochastic network calculus are employed to characterize the maximum arrival rates that can be supported by the wireless channel when HARQ-IR is adopted. Effective capacity is employed as the throughput metric, and a closed-form expression for the effective capacity of HARQ-IR is determined for small values of the quality-of-service (QoS) exponent. The impact of the fixed transmission rate, queuing constraints, and hard-deadline limitations on the throughput is investigated, and comparisons with type-I HARQ and HARQ with Chase Combining are provided.

A combined hybrid ARQ error control and adaptive scheduling scheme is proposed for TDMA/TDD MAC protocols in wireless ATM networks. The type-II hybrid ARQ is chosen as the error recovery scheme, while adaptive fair-queueing is designed to achieve a fair and efficient resource allocation. In particular, the weight of a connection used in the fair-queueing algorithm is dynamically adjusted according to the varying channel conditions and the types of services. Simulation results show that the proposed scheme can achieve better throughput and transfer reliability with minimized delay and cell loss rate when compared with the conventional MAC layer control.

This paper presents a cross-layer design of adaptive modulation and coding (AMC) with truncated hybrid automatic repeat request (HARQ) for one-to-many multicast transmission, in order to increase the spectral efficiency under the quality-of-service (QoS) constraints. For adaptive transmission over the channel common to the multicast group users, the AMC mode is chosen with the minimum SNR among the users to guarantee the target performance of all users. In the meanwhile, the minimum SNR required to support an AMC mode is aggressively designed by allowing retransmission with HARQ schemes. For the proposed design, we derive the average packet error rate, average number of transmission, and spectral efficiency and provide the performance numerically obtained. Numerical results show that the cross-layer design for multicast provides a significant performance gain at a small number of retransmissions as in unicast. In particular, it is observed that AMC design with HARQ is more beneficial in the low SNR region where multicast performs worse than unicast.

This paper investigates the secure transmission in hybrid automatic repeat request (HARQ)-assisted non-orthogonal multiple access (NOMA) networks, where a security-required (SR) user is paired with an opportunity-served (OS) user to perform NOMA. Different from the previous works where NOMA and HARQ are separately considered for secure transmissions, in this paper, both NOMA and HARQ are utilized to enhance the security of the SR user. We derive the closed-form expressions for connection outage probability (COP), secrecy outage probability (SOP), reliable and secure transmission probability (RSP) and effective secrecy throughput (EST) of the SR user in both maximum ratio combining (MRC) and selection combining (SC) schemes. The security-reliability trade-off (SRT) results of the SR user in both MRC and SC schemes are also provided. Analysis and simulation results show that HARQ improves secrecy performance in MRC and SC schemes in terms of RSP, especially in low transmit power region. Besides, since every retransmission is utilized in the MRC scheme, it strictly outperforms the SC scheme in terms of the SRT metric. However, the SC scheme has the potential to achieve higher EST than the MRC scheme by optimizing the transmit power or the power allocation factor. Significantly, the quality of service (QoS) of the OS user can be guaranteed by pairing an SR user who is far away from the transmitter and the secrecy performance of the SR user can be enhanced by pairing an OS user.

We evaluate the performance of an adaptive error correction scheme for wireless ATM networks (WATM). This scheme attempts to minimize the system throughput in order to satisfy the user defined quality of service (QoS) constraints. Indeed, error control for high speed wireless ATM networks is an important research topic, even wireless communication channels are highly affected by unpredictable factors like co-channel interference, adjacent channel interference, propagation path loss and multipath fading. We propose an intelligent-agent architecture to implement our mechanism A-BCH-FEC (adaptive BCH FEC scheme) for a Rayleigh fading environment. Intelligent agents are distributed over all system entities. In the latter, base station agents cooperate with other agents to choose the appropriate BCH coding scheme related to a specific level of signal-to-noise-ratio (SNR). Finally, we illustrate our implementation by some simulation results from a cellular system. These results show that the adaptive scheme using BCH codes improves significantly the system performance.

This paper is concerned with a wireless access system with adaptive modulation and coding (AMC) at the physical layer (PHY), Type-Ill hybrid automatic repeat request (HARQ) at the data link layer (LL) and transport control protocol (TCP) at the transport layer. In order to evaluate the quality-of-service (QoS) of TCP, we analyze the queueing behavior induced by both AMC and Type-Ill HARQ with an embedded Markov chain and study the interaction between AMC, Type-Ill HARQ and TCP via a fixed-point procedure. To maximize the TCP throughput for QoS-guaranteed traffic, we propose a cross-layer design which optimizes the target packet error rate (PER) for AMC at the PHY as well as the maximum number of retransmission for Type-III HARQ at the LL.

With networks increasingly moving into virtually every aspect of our daily life, security is gaining importance, not only from the traditional perspective of communication but the network's growing role in modern automation and control. The traditional, certification based approach attempts to guarantee the security of a network through certification. Certified networks are generally confined to a limited domain and, as a result, they are isolated, costly, and under-utilized. In contrast, this paper presents a new principle – user-level, security-on-demand system, wherein the network allocates, where possible, the security resources commensurate with the user's request for transporting message(s) through the network securely. This principle is successfully demonstrated for the current Asynchronous Transfer Mode (ATM) networks, and is the result of an integration of the fundamental framework for network security, recently proposed by the authors in the literature, with the unique characteristics of ATM networks. The framework encapsulates the fundamental knowledge and set of relationships in network security and permits scientific and systematic reasoning about network security. It also enables all user groups – military, government, industry, and academia, to define their security requirements in a uniform manner. The security-on-demand approach promises the development of a "mixed use" class of networks in the future that may be simultaneously shared by different groups of users, with the system sustaining the diverse security requirements of each user. A unique characteristic in ATM network design is the dynamic call setup process. Under it, a network first establishes a virtual path or route for a user's call, guided by the user's requirements, and then transports the messages when a route has been successfully determined. This unique ATM characteristic is integrated with the framework to yield a successful demonstration of the proposed, user-level, security-on-demand approach. Utilizing the security framework as the foundation, every element of the network – node and link, is characterized by a security matrix that reflects its security resources. Every user is permitted to specify the security requirement for the call through a matrix, which expresses the limits of the security resources that the traffic cells must encounter during their transport through the network. Thus, during the dynamic establishment of the virtual path, every node and link is examined to ensure that the user-specified security is met, in addition to bandwidth and other Quality of Service (QoS) requirements. Traffic is launched when the call setup succeeds, otherwise, the call fails. Like all networks, the ATM network inherently consists of geographically dispersed entities and, as a result, the resource allocation strategy is necessarily distributed. Furthermore, as the network operation progresses, the resource availability scene changes dynamically. This paper proposes a unique function that reduces the key network resource parameters at a node to a single value, termed Node Status Indicator (NSI). The NSI value is computed dynamically at every node and disseminated across the network to be utilized by a node to refine its determination of a virtual path for a user call. The aim of the NSI is to improve the resource utilization in the network. The proposed approach is modeled for a large-scale, representative, 40-node ATM network. Utilizing stochastic input traffic that is synthesized to reflect realistic operating conditions, the model is simulated extensively on a testbed of 35+ Pentium workstations, under Linux, configured as a loosely-coupled parallel processor, utilizing an accurate, asynchronous, distributed simulator. The simulator implements the key characteristics of the ATM Forum proposed P-NNI 1.0 and UNI 3.0 standards. While the simulation results reflect a successful realization of the proposed approach, analysis reveals minimal impact of incorporating security on ATM network performance, as measured through call success rates and call setup times. In contrast, the tradition has been to incorporate security into large-scale systems and networks as an afterthought, i.e. adding hardware and software devices after the design has been completed, resulting in performance degradation. Also, while the use of NSI is observed to yield slightly lower average call setup rates and slightly higher average call setup times, a careful analysis of the trace of the calls as they progress through the system, reveals that, in general, calls are dispersed throughout the network, seeking to utilize all available resources of the network more evenly.

In this research work, the authors propose an error constrained data transmission approach using non-orthogonal multiple access (NOMA) protocol with hybrid automatic repeat request (HARQ) and different packet combining schemes. In this proposed work, the transmitter simultaneously transmits two data packets to the users (UEs) by considering the superposition coding technique in the power domain. The decoding scheme of the receiver changes according to the message decoding status in the previous rounds. This combined protocol has the capability of realizing ultra-reliability, error correction power in high error prone wireless links. The receiver adopts successive interference cancelation (SIC) to decode its own packet. Retransmission process is performed when the data is erroneously received by the destination and the receiver corrects the error by applying HARQ with Packet Combining (HARQ-PC) and HARQ with Aggressive Packet Combining (HARQ-APC) schemes. This paper analyzes the data rates, outage probabilities and bit error rates of UEs for downlink NOMA systems with respect to the transmit power using some basic parameters. The proposed schemes can greatly outperform the conventional NOMA with HARQ (NOMA-HARQ) in terms of data rates, outage probability and bit error rate in dynamic wireless channels.

Emerging low date-rate Machine-to-Machine (M2M) communications call for promising Hybrid Automatic Repeat-reQuest (HARQ) schemes with improved link reliability and feedback efficiency. This motivates us to develop a novel adaptive HARQ scheme by exploiting the knowledge of Channel Quality Information (CQI), which can be obtained through either channel estimation techniques or location- aided technology. The proposed adaptive HARQ scheme will determine the suitable transmission mode to guarantee a specific Frame Error Rate (FER) during the first transmission with the aid of location information. Simulation results demonstrated that our proposed scheme can achieve more attractive throughput performance, while maintaining a similar FER, compared to conventional HARQ schemes.

An asynchronous transfer mode (ATM) network is a high-speed multimedia network which handles various kinds of traffic with different bit-rates and different qualities of service (QoS). In order to maintain the QoS for each traffic source and to avoid possible congestion problems, an ATM network requires highly sophisticated and flexible controllers to insure that this demanding performance can be achieved under unexpected changes in traffic conditions. In this paper, we propose an intelligent architecture using recurrent neural networks and an expert system for traffic control in ATM networks. This traffic control using neural networks is suitable for ATM because neural networks can learn the traffic characteristics and the dynamic changes in the traffic. The proposed mechanism is based on the adaptive prediction of the future values of the traffic and the flow rate for each traffic source. At every given time slot, the controllers in the proposed architecture predict whether the congestion will happen or not and regulate the volume of input traffic for each traffic source before the congestion happens, maintaining the user-required QoS for each traffic source based on the predefined rules. Consequently, the mechanism guarantees the QoS for each traffic source and efficiently prevents congestion.

We propose a new data link control protocol for wireless ATM networks. This new protocol can support both real time and non-real-time services by adopting different error control mechanisms. For real-time traffic, only forward error control (FEC) is used for error correction. For non-real-time traffic, a hybrid automatic repeat request (ARQ) scheme is adopted to reduce the cell loss ratio to a minimum level. In both the FEC and hybrid ARQ schemes, the coding rate is adapted to the channel conditions. When the signal-to-noise ratio (SNR) is high, the coding rate may be higher; while when the channel is bad, the coding rate is adjusted to be lower. The automatic coding rate adaptiveness guarantees the high utilization of the scarce wireless channel resources.

This paper considers the influence of switch fabric design on the performance of resource allocation and connection admission algorithms for asynchronous transfer mode (ATM) networks. In particular, the goal of predictable and guaranteed quality of service (QoS) can be achieved within an ATM network by considering the above factors in the design of the ATM switch fabric. The paper focuses on the identification of the functional requirements of the switch fabric at the ATM layer, and develops an improved architecture which considers QoS at the switch fabric, along with an interface to the resource management. The resultant switch results in ATM networks which have reliable and predictable parameters and which have reduced complexity in connection admission control.