Adaptive Retransmission Design for Wireless Federated Edge Learning

As a popular distributed machine learning framework,wireless federated edge learning(FEEL)can keep original data local,while uploading model training updates to protect privacy and prevent data silos.However,since wireless channels are usually unreliable,there is no guarantee that the model updates uploaded by local devices are correct,thus greatly degrading the performance of the wireless FEEL.Conventional retransmission schemes designed for wireless systems generally aim to maximize the system throughput or minimize the packet error rate,which is not suitable for the FEEL system.A novel retransmission scheme is proposed for the FEEL system to make a tradeoff between model training accuracy and retransmission latency.In the proposed scheme,a retransmission device selection criterion is first designed based on the channel condition,the number of local data,and the importance of model updates.In addition,we design the air interface signaling under this retransmission scheme to facilitate the implementation of the proposed scheme in practical scenarios.Finally,the effectiveness of the proposed retransmission scheme is validated through simulation experiments.

A New HARQ Scheme for 5G Systems via Interleaved Superposition Retransmission

Within the framework of the 5G new radio(NR),we propose a new hybrid automatic repeat request(HARQ)scheme to improve the throughput performance.The difference between the proposed scheme and the conventional one lies in the first retransmission,where the erroneous coded block group is interleaved and superimposed(XORed)onto a fresh coded block group.At the receiver,an iterative message-passing decoding algorithm can be employed to recover the target erroneous code block group(CBG).Only when the superposed retransmission fails,the conventional incremental redundancy(IR)or repetition redundancy(RR)retransmission is initiated.In any case,since the first retransmission is along with but has negligible effect on the fresh CBG,it costs neither transmitted power nor bandwidth.Monte-Carlo simulation results reveal that the presented HARQ schemes can achieve throughput improvements up to 10%over block fading channels and up to 50%over fast fading channels in comparison with the original 5G CBG-level HARQ scheme but without excessively increasing the implementation complexity.

Mechanism of Fast Data Retransmission in CU-DU Split Architecture of 5G NRG

The 5G radio access network （RAN） architectm＇e is supposed to be split into the central unit （CU） and the distributed unit （DU） in order to support more flexible transport networks and provide enhanced user experience. However, such functional split may also introduce some new technical issues. In this pa- per, we study the data fast retransmission issue introduced by this functional split in different scenarios and solutions are provided to handle this issue. With the fast data retransmis- sion mechanism proposed in this paper, the retransmitted da- ta packets could be identified and handled with high priority. In this way, the data delivery between the CU and DU in 5G RAN is assured.

AN ADAPTIVE OPPORTUNISTIC RETRANSMISSION CONTROL SCHEME ENVIRONMENT-AWARE-BASED FOR WIRELESS MULTIMEDIA MESH NETWORKS

In this paper, we propose an aware-based adaptive opportunistic retransmission control scheme for wireless multimedia Mesh networks. The proposed scheme provides maximum retransmis-sion count optimization based on environment-aware to improve packet relay probability. The scheme discriminates the types of packet loss in wireless link by means of environment information and selects the retransmission count by taking the IEEE 802.11 wireless channel characteristics into consideration. Furthermore, the maximum retransmission count of MAC is adjusted adaptively. Extensive simulations demonstrate that the proposed scheme significantly reduces packet collision probability and packet loss rate, and thus improves network throughput.

The Overload Reduction in SIP Servers through Exact Regulation of the Retransmission Timer of the Invite Message

To initiate voice, image, instant messaging and general multimedia communication, the Session communication must initiate between two participants. SIP (Session initiation protocol) is an application layer control, which task is creating management, and terminating this kind of Sessions. With regard to the independence of SIP from the Transport layer protocols, the SIP messages can be transferred on a variety of Transport layer protocols such as TCP or UDP. The mechanism of Retransmission, which has been embedded in SIP, is able to compensate the missing Packet loss, if needed. The application of this mechanism is when SIP messages are transmitted on an unreliable transmission layer protocol such as UDP. This mechanism, while facing with SIP proxy with overload, causes excessive filling of proxy queue, delays the increase of other contacts and adds the amount of the proxy overload. We in this article, while using UDP, as the Transport layer protocol, by regulating the Invite Retransmission Timer appropriately (T1), have improved the SIP functionality. Therefore, by proposing an Adaptive Timer of Invite message retransmission, we have tried to improve the time of Session initiation and as a result, improving the performance. The performance of the proposed SIP, by the SIPP software in a real network environment has been implemented and evaluated and its accuracy and performance has been demonstrated.

Efficient wireless multicast retransmission using network coding

In wireless multicast, network coding has recently attracted attentions as a substantial improvement to packet retransmission schemes. However, the problem of finding the optimal network code which minimizes the retransmissions is hard to solve or approximate. This paper presents two schemes to reduce the number of retransmissions for reliable multicast efficiently. One is retransmission using network coding based on improved Vandermonde matrix （VRNC）, the other is retransmission using network coding based on adaptive improved Vandermonde matrix （AVRNC）. Using VRNC scheme the sender selects the packets all receivers have lost and encodes them with improved Vandermonde matrix; when receivers receive enough encoded retransmission packets, all the lost packets can be recovered. With AVRNC scheme, the sender can obtain the recovery information from all the receivers after sending out per retransmission packet, and then the improved Vandermonde matrix can be updated, thus reducing the complexity of encoding and decoding. Our proposed schemes can achieve the theoretical lower bound assuming retransmission packets lossless, and approach the theoretical lower bound considering retransmission packets loss. Simulation results show that the proposed algorithms can efficiently reduce the number ofretransmissions, thus improving transmission efficiency.

Fault-Tolerant Design for Data Efficient Retransmission in WiNoC

There is a sharp decline in the network performance when the wireless link fails as a data path in the Wireless Network-on-Chip(WiNoC).To counteract this problem,we propose a fault-tolerance mechanism for the efficient retransmission of data in the WiNoC.When an error is detected in the data transmission process,this mechanism works to feed back the fault information to the source node in real time via fault signal lines.In the source node,the highest transmission priority is assigned to the backup retransmitted data,and the corresponding direct link is positioned to enable the data packet for its efficient retransmission to the destination node,thereby ensuring efficiency in fault tolerance.Additionally,we have improved the receiving port of the wireless router,added the corresponding redundant buffers and mux,and dynamically selected the retransmitted non-faulty data packets to be written to the local router in order to avoid the disorderly retransmission of the data packets.The evaluation results of this paper demonstrate that compared with the methods which are under different fault conditions,this fault-tolerant method drastically improves the data throughput rate,reduces the delay,effectively guarantees the reliability of the network,and improves the system performance.

Global optimum encoding packet selection mechanism based on opportunistic network coding for wireless network retransmission

Packet loss cannot be avoided in wireless network due to wireless transmission medium particularity, therefore improving retransmission efficiency is meaningful to wireless transmission. The current retransmission packet selection mechanisms based on oppornistic network coding （ONC） face low retransmission efficiency and high computational complexity problems. To these problems, an optimized encoding packet selection mechanism based on ONC in wireless network retransmission （OONCR） is proposed. This mechanism is based on mutual exclusion packets and decoding gain concepts, and makes full use of ONC advantages. The main contributions of this scheme are to control the algorithm eomplexity of the maximum encoding packets selection effectively, avoid the redundancy encoding packets due to the overlapping among encoding packets, and take the encoding packet local and global optimization problem into consideration. Retransmission efficiency is evaluated according to the computational complexity, the throughput, the retransmission redundancy ratio, and the number of average retransmission. Under the various conditions, the number of average retransmission of OONCR is mainly lower than that of other typical retransmission packet selection schemes. The average retransmission redundancy ratios of OONCR are lower about 5%-40% compared with other typical schemes. Simultaneously the computational complexity of OONCR is comparatively lower than that of other typical schemes.

Retransmission in the network-coding-based packet network

In this paper, retransmission strategies of the network-coding-based packet network are investigated. We propose two retransmission strategies, the packet-loss-edge-based retransmission strategy (PLERT) and the minimum retransmission strategy (MRT), which focus on optimizing the retransmission efficiency without the constraint on the encoding field size. We compared the performances of the proposed retransmission strategies with the traditional automatic repeat-request (ARQ) strategy and the random retransmission strategy. Simulation results showed that the PLERT strategy works well when the packet loss rate is small. Among these retransmission strategies, the performance of the MRT strategy is the best at the cost of the high complexity that is still polynomial. Furthermore, neither of the proposed strategies is sensitive to the encoding field size.

Design and Implementation of Secure and Reliable Information Interaction Architecture for Digital Twins

In order to improve the comprehensive defense capability of data security in digital twins(DTs),an information security interaction architecture is proposed in this paper to solve the inadequacy of data protection and transmission mechanism at present.Firstly,based on the advanced encryption standard(AES)encryption,we use the keystore to expand the traditional key,and use the digital pointer to avoid the key transmission in a wireless channel.Secondly,the identity authentication technology is adopted to ensure the data integrity,and an automatic retransmission mechanism is added for the endogenous properties of the wireless channel.Finally,the software defined radio(SDR)platform composed of universal software radio peripheral(USRP)and GNU radio is used to simulate the data interaction between the physical entity and the virtual entity.The numerical results show that the DTs architecture can guarantee the encrypted data transmitted completely and decrypted accurately with high efficiency and reliability,thus providing a basis for intelligent and secure information interaction for DTs in the future.

Streaming and congestion control using scalable video coding based on H.264/AVC

This paper presents a streaming system using scalable video coding based on H.264/AVC. The system provides a congestion control algorithm supported by channel bandwidth estimation of the client. It uses retransmission only for packets of the base layer to disburden the congested network. The bandwidth estimation allows for adjusting the transmission rate quickly to the current available bandwidth of the network. Compared to binomial congestion control, the proposed system allows for shorter start-up times and data rate adaptation. The paper describes the components of this streaming system and the results of experiments showing that the proposed approach works effectively for streaming video.

RTP-Packets’ Loss Recovery Scheme Based on Layered Buffer-Routers

This paper introduces an RTP-packets' loss recovery scheme in MPEG-4 playback type multicast application model, which is based on retransmission scheme. Through the auxiliary and coordinated buffer playing scheme of layered “buffer-routers”, the RTP-packets' loss recovery in limited time is made possible. We consider in the scheme to handle retransmission request with buffer waiting when network congestion occurs. Thus, neither the degree of congestion will be worsened nor the retransmission request will be lost when sending the request to higher-level buffer router. The RTP-packets' loss recovery scheme suggested by us is not only applied to MPEG-4 multicast application in LAN, but also can be extended to more spacious WAN (wide area network) when user groups comparatively centralize in certain number of local areas. Key words MPEG-4 - retransmission - RTP - loss recovery CLC number TP 393 Foundation item: Supported by the “Tenth Five-year Plan” 211 Engineering Construction ItemBiography: XU Xian-bin(1954-), male, professor Ph. D candidate, research directions: computer network and communication, distributed parallel processing, mass information storage.

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.

Markov Model for Packet Scheduling in the Transmission of Streaming Media

The difficulties in the transmission of streaming media are analyzed, the packet scheduling on the streaming media server is studied. A Markov model is proposed under the effect of the complex dependency among the streaming media packets and the parameters of the transmission channel. On the basis of the Markov model, a policy is made to queue the streaming media packets in the sending buffer by using the iteration method, which can optimize the playback quality under the lack of the channel bandwidth.

Transmission Delay Based Control over Networks with Wireless Links

To achieve the mobility of computers during communication, the TCP connections between fixed host and mobile host may often traverse wired and wireless networks, and the recovery of losses due to wireless transmission error is much different from congestion control. The paper analyzes the side effect of RTT estimation while making the TCP source to handle congestion and wireless error losses properly. Then present a strategy using information feedback by the last hop acknowledgement and monitoring the queuing level of the wired bottleneck link by calculating the changes in transmission delay along the path. With the identification of the early stage of congestion, it can respond to wired congestion quickly while keeping wireless link more reliable, and make TCP react to the different packets losses more appropriately.

Adaptive Control of Congestion in Tough Wireless Environments Using DCM+ Algorithm

The aim of this paper is to present DCM+, a new congestion control protocol for data networks. It stands for Dynamic Congestion control for Mobile networks. New metrics have been newly invented and introduced like normalized advancing index (NAI) and complete transmission time (CTT). The simulations are done for a simple single-hop-topology (sender-router-receiver). The outcomes of this protocol are excellent and, in most cases, better than other approaches. The excellent properties of our proposed protocol were possible through tracking the available slow-start threshold. We achieved performance improvement, minimized end-to-end delay and large reduction in transmission time. DCM+ was able to combine many advantages at same time of the protocols NewReno and Westwood+. The results show, that DCM+ is extremely adequate for different types of networks. Feedback as main principle of control theory was used to control the congestion in the network. The parameters Round-Trip-Time (RTT) and Retransmission Timeout (RTO) are used as feedback signals to adjust the next congestion window (cwnd).

Balance energy-efficient and real-time with reliable communication protocol for wireless sensor network

In many wireless sensor network applications, it should be considered that how to trade off the inherent conflict between energy efficient communication and desired quality of service such as real-time and reliability of transportation. In this paper, a novel routing protocols named balance energy-efficient and real-time with reliable communication （BERR） for wireless sensor networks （WSNs） are proposed, which considers the joint performances of real-time, energy efficiency and reliability. In BERR, a node, which is preparing to transmit data packets to sink node, estimates the energy cost, hop count value to sink node and reliability using local information gained from neighbor nodes. BERR considers not only each sender＇ energy level but also that of its neighbor nodes, so that the better energy conditions a node has, the more probability it will be to be chosen as the next relay node. To enhance real-time delivery, it will choose the node with smaller hop count value to sink node as the possible relay candidate. To improve reliability, it adopts retransmission mechanism. Simulation results show that BERR has better performances in term of energy consumption, network lifetime, reliability and small transmitting delay.

Research of multi-path routing based on network coding in space information networks

A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks. On the basis of traditional multi-path routing, the algorithm uses a random linear network coding strategy to code data pack- ets. Code number is determined by the next hop link status and the number of current received packets sent by the upstream node together. The algorithm improves retransmission and cache mechanisms through using redundancy caused by network coding. Meanwhile, the algorithm also adopts the flow distribution strategy based on time delay to balance network load. Simulation results show that the proposed routing algorithm can effectively improve packet delivery rate, reduce packet delay, and enhance network performance.

An Overview of Data-Importance Aware Radio Resource Management for Edge Machine Learning

The 5G network connecting billions of Internet of things(IoT)devices will make it possible to harvest an enormous amount of real-time mobile data.Furthermore,the 5G virtualization architecture will enable cloud computing at the(network)edge.The availability of both rich data and computation power at the edge has motivated Internet companies to deploy artificial intelligence(AI)there,creating the hot area of edge-AI.Edge learning,the theme of this project,concerns training edge-AI models,which endow on IoT devices intelligence for responding to real-time events.However,the transmission of high-dimensional data from many edge devices to servers can result in excessive communication latency,creating a bottleneck for edge learning.Traditional wireless techniques deigned for only radio access are ineffective in tackling the challenge.Attempts to overcome the communication bottleneck has led to the development of a new class of techniques for intelligent radio resource management(RRM),called data-importance aware RRM.Their designs feature the interplay of active machine learning and wireless communication.Specifically,the metrics that measure data importance in active learning(e.g.,classification uncertainty and data diversity)are applied to RRM for efficient acquisition of distributed data in wireless networks to train AI models at servers.This article aims at providing an introduction to the emerging area of importance-aware RRM.To this end,we will introduce the design principles,survey recent advancements in the area,discuss some design examples,and suggest some promising research opportunities.

Rate control for streaming media transmission over WLAN

In order to solve the problems of link layer retransmission and packet fragment strategies for IEEE 802.11,this paper proposes a variable packet TCPfriendly rate control(VPTFRC)scheme for streaming media transmission over wireless local area network(WLAN)by researching on the policy of packet size adjustment in transport layer based on the minimum retransmit-delay constraint.Unlike other proposals,this process considers the impact of wireless packet error ratio(PER)on the packet size adjustment and the performance of rate control.Simulation results demonstrate that our proposed process can simultaneously achieve higher throughput,better fairness,shorter transmission delay and less jitter than TFRC.Among them,the ratio of delay,jitter and packet loss rate can reach a maximum improvement ratio of 58%,42% and 85% respectively.