Retransmission Request Research Articles

Simulation and analysis of C-V2X data transmission in different traffic scenarios based on MAC layer scheduling algorithms

With the rapid development of communication technology, vehicles are becoming more and more intelligent, and Vehicle to Vehicle (V2V) communication has become an important cornerstone for the future intelligence of vehicles. Because of the high-reliability and low-latency characteristics of 5G networks, many applications can be realized by using Vehicle to Network (V2N) communications. Different applications have different requirements for Quality of Service (QoS), which should be met by the network, and the base station can use different scheduling methods to satisfy these different requirements. This paper focuses on the scheduler at the MAC layer in 5G base stations. The scheduler must handle both video signals and other communication signals transmitted by the vehicle, and must also consider Hybrid Automatic Repeat reQuest (HARQ) retransmissions. We performed a C-V2X signaling network transmission simulation by using OMNeT++. We considered urban and motorway, two public transportation scenarios. Different types of data are set to be transmitted in two scenarios. We used different scheduling schemes for data scheduling, then investigated the performance of these scheduling schemes for transmitting data. The methods and simulation experiments mentioned in this paper are important for practical generalization.

Throughput and delay analysis of cognitive M2M communications

In this paper, we analyze throughput and delay performance of clustered Machine Type Communication (MTC) devices which access an eNodeB utilizing a primary spectrum in underlay mode. We assume that the MTC devices form two clusters and there is an optimal preamble allocation between the two clusters to maximize the throughput. We further investigate the impact of the tolerable interference threshold on throughput, successful preamble decoding probability, and delay. Then, the impact of the preamble partition factor and the access barring factor on throughput and delay is analyzed. Finally, we evaluate the impact of the number of devices, retransmission requests, and preamble partitions on the delay.

Saving Energy and Spectrum in Enabling URLLC Services: A Scalable RL Solution

Communication systems supporting cyber-physical production applications should satisfy stringent delay and reliability requirements. Diversity techniques and power control are the main approaches to reduce latency and enhance the reliability of wireless communications at the expense of redundant transmissions and excessive resource usage. Focusing on the application layer reliability key performance indicators (KPIs), we design a deep reinforcement learning orchestrator for power control and hybrid automatic repeat request retransmissions to optimize these KPIs. Furthermore, to address the scalability issue that emerges in the per-device orchestration problem, we develop a new branching soft actor-critic framework in which a separate branch represents the action space of each industrial device. Our orchestrator enables near real-time control and can be implemented in the edge cloud. We test our solution with a 3GPP-compliant and realistic simulator for factory automation scenarios. Compared to the state-of-the-art, our solution offers significant scalability gains in terms of computational time and memory requirements. Our extensive experiments show significant improvements in our target KPIs, over the state-of-the-art, especially for 5th percentile user availability. To achieve these targets, our framework requires substantially less total energy or spectrum, thanks to our scalable RL solution.

A constructive airborne‐ground matrix algorithm for modern telecommunication systems

AbstractConventional Mobile Communication Systems (MCS) reliably transfer critical messages from authorised remote information sources like military bases and ground control stations in the war field. As tactical advancement grows rapidly, the challenges of transmitting tactical messages via conventional satellite methods increase the processing overhead related to cost, Line of Sight (LOS) communication, packet loss, delay, and retransmission requests. Modern mobile communication systems use Airborne Node Networks (ANN) between satellites and Mobile Ground Nodes (MGNs) as they provide many advantages in mobile communication systems. Hence airborne network reduces the burden of satellites as they are only used as relay stations. The mobility problem caused by ANN and MGNs is solved by proposing a novel constructive airborne‐ground matrix algorithm known as the Who‐To‐Whom (WTW) matrix. With the help of this matrix acting as a reference index, it determines which nodes relate to whom at every time interval T in the tactical environment. This WTW matrix holds precise status/information about connectivity among all stakeholders in the operating environment by carefully and effectively accounting for frequent location changes. The methodology of the proposed matrix is that it contains the physical parameters of the nodes and their behaviour in the tactical environment. The WTW matrix construction algorithm discusses how the reference matrix is constructed in every aerial node to monitor the mobile ground nodes by leading them to safety and providing aerial guidance as they move along the tactical environment. The performance metrics are measured with other existing schemes, and the merits and demerits of the proposed WTW matrix are identified and discussed in detail.

SHM-NDN: A seamless hybrid mobility management scheme for named data mobile ad hoc networks

Named Data Networking (NDN), a counterpart of address-centric networking resolves consumer mobility issues to some extent, however, it confronts excessive bandwidth consumption and network congestion problems in Mobile Adhoc Networks (MANET) due to an inefficient default request re-transmission mechanism. The producer mobility in NDN-based MANET, on the other hand, poses even worse challenges owing to the continuous flooding of location advertisement messages in the network. This paper aims to address the aforementioned producer and consumer mobility issues in MANET and proposes SHM-NDN, a seamless hybrid mobility management scheme for NDN-based MANETs. The proposed scheme features new packet types and extends the functionality of wireless mobile FIB data structure to support efficient mobility management. Moreover, the SHM-NDN proposes a path recovery mechanism to deal with the network partitioning problem caused by a low signal-to-noise ratio and high congestion rate. Through an extensive simulation study, we demonstrate that SHM-NDN achieves on average 12.2% less bandwidth and energy consumption compared to CBILEM. Similarly, SHM-NDN also attains on average 25% less bandwidth and energy consumption compared to EEIF.

Energy efficiency in ARQ-based multi-hop systems and the tradeoff with throughput

The minimum energy per bit (EPB) as the energy efficiency (EE) metric in an automatic retransmission request (ARQ) based multi-hop system is analyzed under power and throughput constraints. Two ARQ protocols including type-I (ARQ-I) and repetition redundancy (ARQ-RR) are considered and expressions for the optimal power allocation (PA) are obtained. Using the obtained optimal powers, the EE-throughput tradeoff (EETT) is analyzed and the EETT closed-form expressions for both ARQ protocols and in arbitrary average channel gain values are obtained. It is shown that how different throughput requirements, especially the high levels, affect the EE performance. Additionally, asymptotic analysis is made in the feasible high throughput values and lower and upper EETT bounds are derived for ARQ-I protocol. To evaluate the EE a distributed PA scenario, as a benchmark, is presented and the energy saving-gain obtained from the optimal PA in comparison with the distributed PA for ARQ-I and ARQ-RR protocols is discussed in different throughput values and node locations.

A Cooperative Automatic Retransmission Request Technique Based on Listening Node Participation Competition

To improve the stability of automatic retransmission requests, a competition control method for automatic retransmission requests of cooperative-based listening nodes is proposed. Because the number of source nodes involved in retransmission communication is reduced, the method reduces the communication energy consumption. Cooperative communication consists of two main parts of work. When the source node sends signals to the surrounding nodes, the relay nodes and other nodes receive the broadcast signals. The signals received by both nodes are the same. A node competition mechanism based on the probability of link disruption as an indicator is designed. The node with higher energy is identified as the node that retransmits the signal. An experiment on the performance comparison of multiple algorithms is organized by simulation. The results show that the proposed new strategy has lower values in BER and BER metrics. This indicates that the proposed method transmits high values of signal quality compared to other dominant methods of retransmitting signals. Because the forwarded signal is successfully transmitted and the source node is no longer involved in the retransmission effort. In cooperative communication, the number of retransmission requests is reduced, and the energy consumed by the system is reduced. Because the improved algorithm achieves low-power communication, the proposed algorithm is practical and innovative in cooperative communication.

Dynamic Manager Selection Assisted Resource Allocation in URLLC With Finite Block Length for 5G-V2X Platoons

In this paper, we investigate a fifth generation cellular vehicle-to-everything based platoon system and propose low-complexity dynamic manager selection and resource allocation algorithms in the finite block length regime, to meet the ultra reliable and low latency communication requirements of intra-platoon safety-related data transmission. A closed-form expression for the platoon manager index is derived, based on which a low-complexity dynamic platoon manager selection algorithm is proposed, enabling a significant communication performance enhancement over the conventional head vehicle platoon manager algorithm. This is also the first work to investigate the impact of finite block length on platoon communication. The optimal finite block length coding rate under automatic repeat request retransmission is obtained. A subchannel multiplexing criterion is proposed and closed-form expressions for the optimal transmission powers of the platoon manager and its subchannel multiplexing partner are derived. Based on the theoretical findings, a joint resource allocation and coding rate optimization algorithm is proposed, achieving a near-optimal performance in terms of groupcast latency with a significant complexity reduction over exhaustive search.

Modeling and Performance Analysis of ECS-HTCARQ Protocol in Interference Scenario

To extend the lifetime of energy-constrained wireless networks, this paper proposes a three-node model of the wireless-powered cooperative communication network (WPCCN). The model consists of an energy-constrained source node, an energy-sufficient relay node, and a destination node and considers two different cochannel interference (CCI) sources at the relay and destination nodes. To ensure the reliability of data transmission, we introduce the cooperative automatic retransmission request (CARQ) protocol, propose the energy-constrained source that harvests and cooperates automatic retransmission request (ECS-HTCARQ) protocol in interference scenario, derive a closed-form expression for the outage probability under Rayleigh fading channels, and establish a discrete-time Markov chain (DTMC) model to analyze the system throughput. The relationship between parameters such as the energy harvesting time allocation factor and energy harvesting efficiency on the outage probability and the system throughput is obtained. Numerical results show that the difference in system throughput is small as the increasing number of transmissions at a high signal-to-interference ratio (SIR), but there is a significant reduction in the outage probability. Finally, the optimal value of the energy harvesting time allocation factor is given under this model.

An Efficient Pro-Active Fault-Tolerance Scheduling of IEEE 802.1Qbv Time-Sensitive Network

Time-sensitive network (TSN) has emerged as one of the enhancement Ethernet technologies of real-time applications for future industrial networks. However, the data of TSN messages may be unexpectedly changed within the transmission duration due to electromagnetic interference. A cyclic redundancy check (CRC) can detect such errors and notify the sender node to retransmit the erroneous message through automatic repeat request (ARQ). The time when the error occurs is uncertain. Consequently, the time when performing the retransmission requests is also random, which results in different transmission sequences and violates the deterministic transmission of TSN. In addition, the returned CRC detection messages also might be at fault during transmission. In order to provide the fault tolerance capability of critical flows in TSN without violating the nature of deterministic transmission, this article proposes a pro-active fault-tolerant TSN scheduling algorithm (PFT-TSN), which not only transmits a certain number of instance copies for critical flows but provides network transmission services for noncritical flows. The challenge is that schedulability and safety of critical flows are tradeoffs in terms of the number of transmissions per instance of critical flows and the schedulability. Moreover, the transmission service of noncritical flows can also affect the schedulability of critical flows. We conduct comprehensive experiments with synthetic networks to show that the proposed method can meet both safety and schedulability requirements for critical flows, and noncritical flows are also allowed to be transmitted by the service degradation.

Common Message Acknowledgments: Massive ARQ Protocols for Wireless Access

Massive random access plays a central role in supporting the Internet of Things (IoT), where a subset of a large population of users simultaneously transmit small packets to a central base station. While there has been much research on the design of protocols for massive access in the uplink, the problem of providing message acknowledgments back to the users has been somewhat neglected. Reliable communication needs to rely on two-way communication for acknowledgement and retransmission. Nevertheless, because of the many possible subsets of active users, providing acknowledgments requires a significant amount of bits. Motivated by this, we define the problem of massive ARQ (Automatic Retransmission reQuest) protocol and introduce efficient methods for joint encoding of multiple acknowledgements in the downlink. The key idea towards reducing the number of bits used for massive acknowledgments is to allow for a small fraction of false positive acknowledgments. We analyze the implications of this approach and the impact of acknowledgment errors in scenarios with massive random access. Finally, we show that these savings can lead to a significant increase in the reliability when retransmissions are allowed since it allows the acknowledgment message to be transmitted more reliably using a much lower rate.

Efficient Reservation-based Fault-Tolerant Scheduling for IEEE 802.1Qbv Time-Sensitive Networking

Time-Sensitive Networking (TSN) is one of the enhanced Ethernet technologies for the real-time application of industrial networks in the future. However, unexpected data errors caused by transient influence like electromagnetic interference may be occurred during the data transmission. One common way to tolerate such failures is to directly transmit multiple instance copies, such as IEEE 802.1 CB. However, wasting limited network resources is one of the drawbacks, since not all message copies could be received incorrectly. Cyclic Redundancy Check (CRC) can detect such errors when data is received, then the detection result is notified to the sending node. Despite that the re-transmission is performed only if the returned detection result is negative or time-out, the occurrence of errors are uncertain. Consequently, the time when responding to the re-transmission requests is also random, which results in different transmission sequences and violates the deterministic transmission service of TSN. Furthermore, CRC detection results messages also might be fault during transmission. To tackle the above drawbacks, we propose a novel offline reservation-based fault-tolerance scheduling algorithm for IEEE 802.1 Qbv TSN. Firstly, the Dijkstra algorithm is used to generate the routing for each flow. Then, the resource allocation is generated by Satisfiability Modulo Theories according to TSN constraints formulated to guarantee the deterministic transmission for Time-Trigger (TT) flows, CRC-related flows, and the reserved re-transmissions of TT flows. Finally, the queues are also open for non-TT flows in the time slice reserved for re-transmissions of TT flows to enhance the throughput of non-TT flows. Through extensive simulations, we demonstrate the effectiveness of the proposed approach in terms of acceptance ratio, execution time and the wasted resources.

HARQ Optimization for PDCP Duplication-Based 5G URLLC Dual Connectivity

Packet duplication (PD) with dual connectivity (DC) was newly introduced in the 5G New Radio (NR) specifications to meet the stringent ultra reliable low latency communication (URLLC) requirements. PD technology uses duplicated packets in the packet data convergence protocol (PDCP) layer that are transmitted via two different access nodes (ANs) to the user equipment (UE) in order to enhance the reliability performance. However, PD can result in unnecessary retransmissions in the lower layers since the hybrid automatic retransmission request (HARQ) operation is unaware of the transmission success achieved through the alternate DC link to the UE. To overcome this issue, in this paper, a novel duplication-aware retransmission optimization (DRO) scheme is proposed to reduce the resource usage induced by unnecessary HARQ retransmissions. The proposed DRO scheme can minimize the average channel use while satisfying the URLLC requirements. The proposed DRO scheme derives the optimal HARQ retransmission attempts for different ANs by solving a nonlinear integer programming (NLIP) problem. The performance of the proposed DRO scheme was evaluated using MATLAB simulation and is compared to the existing 5G HARQ support schemes. The simulations results show that the proposed DRO scheme can provide a 14.71% and 15.11% reduced average channel use gain compared to the selective data duplication upon failure (SDUF) scheme and latency-aware dynamic multi-connectivity algorithm (LADMA) scheme, respectively, which are the existing 5G PD schemes that use HARQ.

Modeling of a controlled retransmission scheme for loss recovery in optical burst switching networks

Retransmission in optical burst switching networks is a solution to recover data loss by retransmitting the dropped burst. The ingress node temporarily stores a copy of the complete burst and sends it each time it receives a retransmission request from the core node. Some retransmission schemes have been suggested, but uncontrolled retransmission often increases the network load, consumes more bandwidth, and consequently, increases the probability of contention. Controlled retransmission is therefore essential. This paper proposes a new controlled retransmission scheme for loss recovery, where the available bandwidth of wavelength channels and the burst lifetime are referred to as network conditions to determine whether to transmit a dropped burst. A retrial queue-based analysis model is also constructed to validate the proposed retransmission scheme. The simulation and analysis results show that the controlled retransmission scheme is more efficient than the previously suggested schemes regarding byte loss probability, successful retransmission rate, and network throughput.

On the Performance Evaluations of Cooperative Retransmission Scheme for Cell-Edge Users of URLLC in Multi-Carrier Downlink NOMA Systems.

Non-orthogonal multiple access (NOMA) has a key feature that the cell-center user (CCU) has prior information about the messages of the cell-edge user (CEU) in the same user-pair. It means that CCU can be used for retransmission when the CEU requests retransmission. As ultra-reliability and low-latency communication (URLLC) requires high-reliability constraints (e.g., 99.999%), using CCU for retransmission can be useful to satisfy the reliability constraint. In this study, to ensure the reliability of CEU, cooperative retransmission (CR) scheme for downlink NOMA systems is proposed. And the CR scheme is evaluated with Block error rate (BLER) considering reliability and with packet loss rate (PLR) in terms of reliability and latency constraints. And the evaluation results showed that the proposed CR scheme can satisfy the target BLER for URLLC low SNR compared to the conventional retransmission scheme, and showed the improved PLR compared to the conventional retransmission scheme in low SNRs.

Spatially Coupled LDPC Codes via Partial Superposition and Their Application to HARQ

This paper proposes a new class of spatially coupled codes, which are constructed by sending codewords of a low-density parity-check block code (LDPC-BC) in a block Markov superposition transmission (BMST) manner, resulting in the BMST-LDPC codes. Different from the conventional spatially coupled LDPC (SC-LDPC) codes, the proposed BMST-LDPC codes can have encoder/decoder implemented using the structure of the corresponding LDPC-BCs. The proposed construction is universal , which is applicable to any existing LDPC-BCs including the 5 G New Radio (5G-NR) LDPC-BCs to obtain extra coding gains. The proposed BMST-LDPC codes are also a special class of BMST codes, which have lower error floors even with an encoding memory of one, inheriting a low decoding latency. Moreover, partial superposition , where a fraction of the coded bits are superimposed onto the following codewords, is introduced to alleviate the decoding error propagation. The construction can be optimized, for random long codes, by a protograph-based extrinsic information transfer (EXIT) chart analysis, or by a one-dimensional search for structured block codes. Furthermore, the BMST-LDPC scheme is integrated with the hybrid automatic retransmission request (HARQ) over the block fading channel, improving the throughput performance. Numerical results are presented to validate our analysis and demonstrate the performance advantage of the BMST-LDPC codes over the LDPC-BCs. They also show that the proposed HARQ scheme can yield a throughput improvement of up to 10% over the conventional HARQ scheme.

A reliable tree-based data aggregation method in wireless sensor networks

Aggregating the sensed data by nodes is a natural way to increase the network lifetime and reduce the number of bits sent and received by each sensor node. This paper presents a reliable tree-based data aggregation method. In the proposed method, sensor nodes are organized in the form of a binary tree. Then, aggregation requests are authenticated by a shared key, and if the request is acknowledged, the aggregation process begins. In the proposed method, using dynamic generator polynomial-size for cycle error detection code (CRC), the error generated along the path is detected hop by hop. In case of an error, the request for retransmission will be sent to the previous hop. Also, intermediate nodes apply certain aggregating functions like summation or averaging on the received packages, which cause a reduction in the amount of data transmission on the network. This method reduces the number of sent packets and the amount of energy consumed, so the network has a longer lifetime. Also, this method significantly increased reliability using the CRC code. The proposed method is compared with EESSDA, SDAACA, and LAG methods. The simulation results show that the proposed method has greater superiority over its comparative techniques, particularly on aspects such as energy consumption, network lifetime, and reliability.

Data Transmission Model with Lost Fragments Recovery Based on Application Layer ARQ

Wireless networks in difficult conditions of signal receiving are characterized by a high level of burst data losses, at which a large number of data fragments can be lost in a row. In this case, to recover the lost data, the use of forward error correction methods (FEC) in most cases does not give a sufficient effect. The use of standard data loss recovery methods based on automatic retransmission request (ARQ) at the data link and transport layers of the OSI model can lead to significant delays, which is often unacceptable for real-time streaming services. In such a case, it may be preferable to skip the piece of data rather than delay waiting for the piece to be delivered on retransmissions. The use of ARQ-based techniques on application layer of OSI model for data streaming allows for a more efficient recovery of lost data chunks in wireless networks with a high level of burst losses. The known models of a discrete channel for wireless networks allow for analytically assessing the probability of data loss, however, they do not take into account cases with retransmission of lost data. The study proposes a mathematical model of data transmission in a wireless communication channel based on the Gilbert model, which takes into account the loss recovery by the ARQ method and allows you to calculate the data loss ratio. To check the adequacy of the proposed model, a software was developed that ensures the transmission of data streaming in a wireless communication network with recovery of fragment losses at the application level, and a corresponding experimental study was carried out. It is shown that the mathematical model takes into account the burstiness of transmitted data losses and their recovery by the ARQ method.

Live Cloud Ingest Using Open Alternatives RIST & SRT

As cloud production becomes an integral part of broadcasters’ live workflows, the corresponding cloud infrastructure becomes an integral part of the media transport network. Cloud infrastructure providers, often public in nature, are accessible either through the public internet or through leased lines. Regardless of public or private, experience shows that these connections are not up to the quality standards required for low latency live streaming media, making quality-enhancing technologies, such as retransmission or Automatic Repeat reQuest (ARQ), an imperative part of the network infrastructure to deliver on the requirements for broadcast quality transmission. Two solutions have emerged as front runners on the quest for the next de facto standard for broadcast retransmission—Reliable Internet Stream Transport (RIST) and Secure Reliable Transport (SRT). This report compares these two alternatives from a theoretical and performance perspective and compares them with a commercial reference alternative .

Reduction of HARQ Latency for URLLC 5G Services Based on Network Slicing and Massive MIMO Hybrid Beamforming

Ultra-Reliable and Low-Latency Communications (URLLC) is one of the three generic 5G services and probably the most challenging one, with strict quality of service requirements of 99.999% or more reliability and less than 1 milliseconds (ms) radio latency. To achieve latency targets, contributors to latency need to be addressed. Hybrid automatic repeat request (HARQ) retransmissions are major contributor to latency and need to be limited. The objective of this paper is to study the benefit of using Massive MIMO (M-MIMIO) along with radio network slicing to reduce number of HARQ retransmissions. A practical type of M-MIMO beamforming named hybrid beamforming is used. The performance of the proposed system is evaluated with slicing, without slicing and by alternating number of data streams per user. This work highlights the importance of technology enablers, such as M-MIMO and network slicing, in addressing quality-of-service (QoS) latency requirements for URLLC applications.