Average Packet Delay Research Articles

A2T-Boost: An Adaptive Cell Selection Approach for 5G/SDN-Based Vehicular Networks

Heterogeneous ultra-dense networks (HUDNs) are one of the key enabling technologies for the fifth-generation (5G) networks. They aim to provide high capacity, low installation cost, and distributed traffic loads. The cell selection is a challenging issue in HUDNs, due to the different characteristics of base stations (BSs) and the existence of a large number of them. Thus, the traditional cell selection scheme is not applicable in such a network. In this paper, a novel adaptive cell selection strategy is proposed, called adaptive two-tier based on adaptive boosting (A2T-Boost). It can adapt to the various characteristics of base stations, as well as the different movement features of mobile stations such as vehicles and pedestrian. It is a software-defined networking (SDN)/machine learning (ML)-based scheme. A real-world case is considered in the downtown of Los Angeles city. Simulation results demonstrate that A2T-Boost achieves high prediction performance and it outperforms other related schemes in terms of average number of handovers (HOs) by up to 50%. Moreover, it enhances the average achievable downlink sum-rates and network energy efficiency achieved by vehicles by up to 33.76%. Furthermore, the average packet delay is decreased using the proposed scheme by up to 12.87%.

Machine Learning Prediction Based Adaptive Duty Cycle MAC Protocol for Solar Energy Harvesting Wireless Sensor Networks

The dynamic nature of energy harvesting rate, arising because of ever changing weather conditions, raises new concerns in energy harvesting based wireless sensor networks (EH-WSNs). Therefore, this drives the development of energy aware EH solutions. Formerly, many Medium Access Control (MAC) protocols have been developed for EH-WSNs. However, optimizing MAC protocol performance by incorporating predicted future energy intake is relatively new in EH-WSNs. Furthermore, existing MAC protocols do not fully harness the high harvested energy to perform aggressively despite the availability of sufficient energy resources. Therefore, a prediction-based adaptive duty cycle (PADC) MAC protocol has been proposed, called PADC-MAC, that incorporates current and future harvested energy information using the mathematical formulation to improve network performance. Furthermore, a machine learning model, namely nonlinear autoregressive (NAR) neural network, is employed that achieves good prediction accuracy under dynamic harvesting scenarios. As a result, it enables the receiver node to perform aggressively better when there is sufficient inflow of incoming harvesting energy. In addition, PADC-MAC uses a self-adaptation technique that reduces energy consumption. The performance of PADC-MAC is evaluated using GreenCastalia in terms of packet delay, network throughput, packet delivery ratio, energy consumption per bit, receiver energy consumption, and total network energy consumption using realistic harvesting data for 96 consecutive hours under dynamic solar harvesting conditions. The simulation results show that PADC-MAC provides lower average packet delay of the highest priority packets and all packets, energy consumption per bit, and total energy consumption by more than 10.7%, 7.8%, 81%, and 76.4%, respectively when compared to three state-of-the-art protocols for EH-WSNs.

An Adaptive Confidentiality Security Service Enhancement Protocol Using Image-Based Key Generator for Multi-Agent Ethernet Packet Switched Networks

Conventional network Security Protocols provide different types of security services that establish secure connections between network nodes making them robust against different security threats. The security establishment process depends on sharing security keys between connected devices. The level of security provided by such security protocols is static and irrelevant to the status of the network. In this paper, we propose an adaptive security-aware lottery-EDF scheduler for limited resources Ethernet packet switched networks using GAIA multi-agent approach. The proposed system adopts a periodic non-shared cryptographic key-generation process of different sizes (i.e., 64 bits, 128 bits, 160 bits, and 512 bits) using the textural features of digital images stored on a central image-server. The proposed system deploys a security enhancement unit that adaptively enhances the confidentiality security-service level for the real-time packets according to feedback from a congestion control scheme that is based on network resource estimation technique, hence making the network robust against the spoofing security threat while preserving the overall network performance metrics (NPMs). By simulating a real-time Ethernet packet switched network, extensive simulation results show the efficiency of the adaptive proposed protocol over the static-security and IPSec protocols in guaranteeing the QoS requirements for the real-time flows in terms of destination’s buffer consumption and average total packet delays.

Optimization of Contention Window and Relay Selection for Efficient Routing Using Fuzzy Logic Model

The rapid increase in vehicle density on roads owing to urbanization and motorization has led to increased risks of roadblocks, traffic jams, and accidents. To ensure the reliability of transportation, it is crucial to have stable and timely transmission of safety messages through Vehicle Ad-hoc Networks (VANETs). However, frequent vehicle movement and changes in the network topology may cause link breakage and packet loss. This paper proposes a solution that uses a fuzzy logic system in both the Medium Access Control (MAC) layer and the network layer to broadcast safety messages efficiently. The proposed rule-based model optimizes the Contention Window (CW) and relay selection process to adapt to different traffic conditions. The dynamic CW MAC (DYCW-MAC) model selects the optimum size of CW based on network parameters such as density, velocity, and link quality factor. For multi-hop communication, the model determines the next forwarding relay by considering factors such as direction, velocity difference, coverage factor, and Fast-Expected Transmission Count (F-ETX) between the sender vehicle and surrounding vehicles within its transmission range. The simulation results indicate that the DYCW-MAC model enhances the network throughput and decreases the average packet delay in comparison to other models.

Buffer-Aided Max-Link Relaying for Free Space Optical Communication With Delay Constraints

In this paper, we introduce the concept of buffer-aided cooperative relaying for a free-space optical (FSO) communication system. The proposed FSO system consists of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$K$</tex-math></inline-formula> decode-and-forward(DF) relays, each equipped with a buffer of size <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L$</tex-math></inline-formula> . The proposed system undergoes both path loss and atmospheric turbulence (AT) induced fading, and to evaluate the system performance a weak, as well as strong AT region is considered. The Markov chain (MC) approach is used to derive the state transition matrix of the system, which is then further used to model the evolution of buffer states. Analytical expressions of the outage probability and average bit error rate (ABER) are obtained with the help of state transition matrix. The average packet delay of the system is also evaluated with the help of obtained outage probability. The performance of the considered system is analyzed for different values of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$K$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L$</tex-math></inline-formula> . The performance is then further compared with the non-buffer-aided (NBA) cooperative relaying for FSO communication systems and it has been observed that the proposed buffer-aided FSO system significantly outperforms the NBA FSO systems for entire range of turbulence. Finally, the impact of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$K$</tex-math></inline-formula> on the average packet delay of the system is examined.

A seven-dimensional state flow traffic modelling for multi-controller Software-Defined Networks considering multiple switches

Software-Defined Networking (SDN) improves flexibility in network management and programmability through decoupling the control and the data planes. In SDN, traffic analysis and modelling are important for tracking network activity and availability to detect abnormalities, such as security and operational problems. In this paper, a seven-dimensional state model is used to model SDN TCP and UDP flows, unlike other models that are used in previous work which use three or four-dimensional states. We formulate seven-dimensional states with transitions which consider flow-level arrivals to get more accurate knowledge about modelling the SDN traffic. The proposed work uses multiple controllers and multiple switches with limited capacities unlike other models in related work which may use one controller or switch with an infinite buffer. Using multiple controllers improves the security of the network, due to the backup capability. In addition, it enhances the network’s scalability since there are enough controllers to serve more switches. Also, using multiple switches can provide more accurate results to better reflect the actual case of traffic in the network. The packet average delay and loss probability are tracked to measure the performance of the developed models. Simulation results are formulated and compared to analytical ones. The results prove that the proposed modelling is accurate compared to the recent work.

A Self-Adaptable Angular Based K-Medoid Clustering Scheme (SAACS) for Dynamic VANETs

Prior study suggests that VANET has two types of communications: Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) communications. V2V is very important and ensures cooperative communications between vehicles and safety measures. It is also defined as Inter-Vehicle Communication (IVC).The communication is based on clustering the nodes to transmit the data from vehicle to vehicle. The overhead and stability are considered as main challenges that need to be addressed during vehicle intersections. In this paper, a novel self-adaptable Angular based k-medoid Clustering Scheme (SAACS) is proposed to form flexible clusters. The clusters are formed by estimating the road length and transmission ranges to minimize the network delay. And the Cluster Head (CH) is elected from a novel performance metric, ‘cosine-based node uncoupling frequency,’ that finds the best nodes irrespective of their current network statistics. The parametric analysis varies according to the number of vehicular nodes with the transmission range. The experimental results have proven that the proposed technique serves better in comparison to existing approaches such as Cluster Head Lifetime (CHL), Cluster Member Lifetime (CML), Cluster Number (CL), Cluster Overhead (CO), Packet Loss Ratio (PLR) and Average Packet Delay (APD). CHL is enhanced 40% as compare to Real-Time Vehicular Communication (RTVC), Efficient Cluster Head Selection (ECHS) whereas CML is 50% better than RTVC and ECHS. Packet loss ratio and overhead is 45% better in our proposed algorithm than RTVC and ECHS. It is observed from the results that the incorporation of cosine-based node uncoupling frequency has minimized the incongruity between vehicular nodes placed in dense and sparse zones of highways.

Design of QoS-aware long-reach optical backhaul for wireless and FTTx networks with enhanced backup resource utilization

• Proposed a long-reach optical access network architecture (LCQ-LR-OAN) that utilizes backup resources for providing the protection and alleviating network congestion. The LCQ-LR-OAN can simultaneously support different types of users with different QoS requirements. • Proposed a partial protection strategy that provides protection to all shared optical resources while keeping the unshared optical resources unprotected. We also developed survivability and network congestion alleviating mechanisms using a single set of optical resources. • Considered user priority (e.g., FTTH, FTTC, FTTB and FTTO) with reference to providing the protection. • Proposed a novel DBA scheme (EBA) to allocate the bandwidth of the backup OLT to the LR-PONs during the network congestion periods. • The LCQ-LR-OAN requires lower cost compared to that of the other existing LR-OAN architectures. The LCQ-LR-OAN architecture does not depend on any specific PON standard, viz., EPON, GPON. Thus, it can be used with all the PON standards. In this paper, we explore a low-cost and quality-of-service (QoS)-aware long-reach optical backhaul for the wireless and fiber-to-the-x (FTTx) networks. We exploit the reserved and idle optical resources to provide protection against failures and offer extra bandwidth to the users in the network congestion hours. We use a single set of optical resources to both provide protection and reduce network congestion, thereby incurring the minimum total expenditure. For the practical network scenarios, the simulation outcomes reveal that the proposed architecture can reduce 11 - 79 % average packet delay in the network congestion hours. It offers higher connection availabilities, i.e., five-nine availability ( ∼ 0.99999 ) with full protection and four-nine availability ( ∼ 0.9999 ) with partial protection. Meantime, it requires ∼ 30 % less capital expenditure cost than the other existing benchmark and state-of-the-art long-reach optical backhaul architectures. The proposed architecture is validated by simulation studies and practical data.

Improved Buffer-Aided Selective Relaying for Free Space Optical Cooperative Communications

This paper tackles the performance analysis and relaying strategies for two-relays buffer-aided (BA) parallel relaying cooperative free space optical (FSO) networks. We first provide an asymptotic analysis of the existing selective relaying scheme that simultaneously activates the strongest source-relay (S-R) and relay-destination (R-D) optical links. We then propose an improvement of this scheme and highlight on its advantages by deriving closed-form accurate expressions for the asymptotic values of the outage probability (OP) and average packet delay (APD). The theoretical evaluation and numerical analysis demonstrate the capability of the improved scheme in enhancing the diversity order with finite buffer sizes unlike the selective relaying scheme that achieves diversity gains only with infinite-size buffers entailing infinite delays. The OP performance is significantly enhanced for all network topologies whether the relays are closer to S, closer to D or placed at the same distance from S and D. On the other hand, the reaped APD gains depend on the positions of the relays.

Research on SDN Fingerprint Attack Defense Mechanism Based on Dynamic Disturbance and Information Entropy Detection

As an emerging type of network architecture, SDN is widespread used and security issues have also received more and more attention. Fingerprint attacks represent one of the most significant threats to network security. Attackers obtain key fingerprint information of the target network, which lays the foundation for subsequent more threatening attacks. Currently, research on domestic and international SDN fingerprint attacks focuses on how to attack, and less research is being done on how to defend against fingerprinting attacks. This paper proposes a mechanism for defending fingerprint attacks that combines dynamic disturbance and information entropy detection. This mechanism adopts the principle of fingerprint attack, combined with a moving average algorithm, Bloom Filter, and packet delay tool, to confuse opponents by disturbing a small number of packets, simultaneously, combined with the information entropy detection to make real-time processing feedback to the network. The experimental results show that this mechanism works effectively to defend SDNs against fingerprint attacks without affecting the normal network communication.

A Novel Deep Learning-Based Cooperative Communication Channel Model for Wireless Underground Sensor Networks.

Wireless Underground Sensor Networks (WUSNs) have been showing prospective supervising application domains in the underground region of the earth through sensing, computation, and communication. This paper presents a novel Deep Learning (DL)-based Cooperative communication channel model for Wireless Underground Sensor Networks for accurate and reliable monitoring in hostile underground locations. Furthermore, the proposed communication model aims at the effective utilization of cluster-based Cooperative models through the relay nodes. However, by keeping the cost effectiveness, reliability, and user-friendliness of wireless underground sensor networks through inter-cluster Cooperative transmission between two cluster heads, the determination of the overall energy performance is also measured. The energy co-operative channel allocation routing (ECCAR), Energy Hierarchical Optimistic Routing (EHOR), Non-Cooperative, and Dynamic Energy Routing (DER) methods were used to figure out how well the proposed WUSN works. The Quality of Service (QoS) parameters such as transmission time, throughput, packet loss, and efficiency were used in order to evaluate the performance of the proposed WUSNs. From the simulation results, it is apparently seen that the proposed system demonstrates some superiority over other methods in terms of its better energy utilization of 89.71%, Packet Delivery ratio of 78.2%, Average Packet Delay of 82.3%, Average Network overhead of 77.4%, data packet throughput of 83.5% and an average system packet loss of 91%.

Buffer State Based Relay Selection for Half-Duplex Buffer-Aided Serial Relaying Systems

This work investigates multi-hop serial relaying half-duplex (HD) networks comprising one source, one destination and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> decode-and-forward (DF) relays. Buffer-aided (BA) relays are considered where finite size buffers are added to relays. For this setup, we propose a novel BA relaying strategy that selects the node that must transmit over one epoch in a block fading environment. Selecting a node depends on the buffer state information of all relays and on the availability of the hops. Moreover, the proposed relaying scheme is controlled by an adjustable parameter that allows the system to achieve multiple levels of tradeoff between the average packet delay (APD) and the outage probability (OP). A Markov chain model is adopted to evaluate the system’s performance and simple closed-form expressions were derived for the APD and OP based on an asymptotic analysis. The performance analysis proves the ability of the suggested relaying scheme to achieve significant OP and APD gains with small buffer sizes. Two variants of the proposed relaying scheme are particularly appealing. The APD-prioritizing variant achieves the smallest APD of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2K$ </tex-math></inline-formula> without improving the diversity order. The second OP-prioritizing variant reaches the full diversity order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K+1$ </tex-math></inline-formula> while increasing the asymptotic APD to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K(K+3)$ </tex-math></inline-formula> .

Risk-Resistant Resource Allocation for eMBB and URLLC Coexistence Under M/G/1 Queueing Model

In this paper, we study the joint resource scheduling problem for multiplexing two distinct 5 G services: enhanced mobile broadband (eMBB) and ultra-reliable low latency communications (URLLC). While eMBB services require high data rates, URLLC services lay more emphasis on extremely low latency and high reliability. To satisfy these heterogeneous requirements for eMBB and URLLC coexistence, we propose a risk-resistant scheme for resource allocation to both eMBB and URLLC traffic that aims to maximize the eMBB data rate, while considering the URLLC delay threshold violation to maintain URLLC delay requirements. Based on the M/G/1 queueing model, the URLLC packet latency target is realized by minimizing the average packet delay in violation cases, where &#x201C;violation&#x201D; is judged by introducing the &#x201C;conditional value at risk (CVaR)&#x201D; as a risk metric (i.e., &#x201C;risk&#x201D; here is defined as URLLC delay threshold violation). To solve the formulated problem, we transform it into two convex optimization problems to obtain a near-optimal resource allocation solution. Simulation results show that the proposed scheme improves the fairness among the eMBB users and eMBB throughput by <inline-formula><tex-math notation="LaTeX">$30\%\sim 34\%$</tex-math></inline-formula> compared to existing works, while satisfying the stringent URLLC delay requirements.

Secure Location-Aided Routing Protocols With Wi-Fi Direct For Vehicular Ad Hoc Networks

Secure routing protocols are proposed for the vehicular ad hoc networks. The protocolsintegrate the security authentication process with the Location-Aided Routing (LAR) protocol to supportWi-Fi Direct communications between the vehicles. The methods are robust against various security threats.The security authentication process adopts a modified Diffie-Hellman key agreement protocol. The Diffie-Hellman protocol is used with a short authentication string (SAS)-based key agreement over Wi-Fi Directout-of-band communication channels. It protects the communication from any man-in-the-middle securitythreats. In particular, the security process is integrated into two LAR routing schemes, i.e., the request-zoneLAR scheme and the distance-based LAR scheme.We conduct extensive simulations with different networkparameters such as the vehicular node density, the number of the malicious nodes, and the speed of thenodes. Simulation results show that the proposed routing protocols provide superior performance in securedata delivery and average total packet delay. Also, the secure distance-based LAR protocol outperforms thesecure request-zone LAR protocol.

Fuzzy Based Optimal QoS Constraint Services Composition in Mobile Ad Hoc Networks

In recent years, computational capability of mobile devices such as Laptops, mobile phones, PDAs, etc., are greatly improved. Implementation of SOA ("Service Oriented Architectures") in mobile ad hoc networks increases the flexibility of using mobile devices. On composing different available services to satisfy end user requirement is a critical challenge in MANETs ("Mobile Ad Hoc Network") due to dynamic topology, Resource heterogeneity, Band width constraint and highly distributed service providers. Existing composition services approaches are not suitable for MANETs due to lack of constraints consideration while choosing services. In this paper, we proposed Fuzzy based optimal QoS constrained Service Composition in MANETs. We consider Energy constraint, hop count, Response time &amp; service throughput as QoS Constraints composing optimal services. We proposed fuzzy logic based system to provide rating to the services for optimal selection of services. We also considered that each node can provide one or more services. The service composition failure rate will be reduced by selecting optimal services in available services. The simulation result demonstrates that the proposed method outperformed than the traditional AODV in terms of average packet delay, energy constraint, throughput and turnaround time.

Enhancing the performance of downlink NOMA relaying networks by RF energy harvesting and data buffering at relay

Recently, non-orthogonal multiple access (NOMA) and energy harvesting (EH) from radio frequency (RF) have been considered as promising candidates for next-generation mobile communications. In this paper, we investigate a novel solution to enhance the reliability and the supply stability of a downlink NOMA relaying networks, in which we integrate two techniques: (i) simultaneous wireless information and power transfer, i.e. the relay node can harvest the energy from source signals and use this energy to help forward information from source node to two user nodes; and (ii) data buffer aid at relay node, i.e. the data packets received from the source can be stored in a buffer and then be re-transmitted to the destination nodes only when the channel condition is good. The performance of the proposed system is analyzed rigorously to derive the system outage probability (OP), throughput and the average packet delay. Furthermore, a power allocation optimization problem to minimize the OP is formulated and solution to this problem is also provided. In addition, the optimal transmission rates to maximize the throughput of each user are presented in numerical results. Monte Carlo simulations are conducted to verify the analytical results, which confirms that with data buffer at relay, the overall outage probability (OOP) can be reduced significantly.

Adaptive Hurst-Sensitive Active Queue Management.

An Active Queue Management (AQM) mechanism, recommended by the Internet Engineering Task Force (IETF), increases the efficiency of network transmission. An example of this type of algorithm can be the Random Early Detection (RED) algorithm. The behavior of the RED algorithm strictly depends on the correct selection of its parameters. This selection may be performed automatically depending on the network conditions. The mechanisms that adjust their parameters to the network conditions are called the adaptive ones. The example can be the Adaptive RED (ARED) mechanism, which adjusts its parameters taking into consideration the traffic intensity. In our paper, we propose to use an additional traffic parameter to adjust the AQM parameters—degree of self-similarity—expressed using the Hurst parameter. In our study, we propose the modifications of the well-known AQM algorithms: ARED and fractional order and the algorithms based on neural networks that are used to automatically adjust the AQM parameters using the traffic intensity and its degree of self-similarity. We use the Fluid Flow approximation and the discrete event simulation to evaluate the behavior of queues controlled by the proposed adaptive AQM mechanisms and compare the results with those obtained with their basic counterparts. In our experiments, we analyzed the average queue occupancies and packet delays in the communication node. The obtained results show that considering the degree of self-similarity of network traffic in the process of AQM parameters determination enabled us to decrease the average queue occupancy and the number of rejected packets, as well as to reduce the transmission latency.

Delay performance of priority-queue equipped UAV-based mobile relay networks: Exploring the impact of trajectories

UAV-based mobile relay communication systems have an important position in future wireless networks, such as Beyond 5G and 6G, which provide ubiquitous network services. Along this line, UAV-based single-hop relay systems have numerous applications in emergency situations, such as data ferry and assisting post-disaster areas. Although there have been numerous works on optimizing trajectories and other communication resources on such systems, there are few studies on delay performance at the granular packet level. In addition to having homogeneous traffic, such a system can be equipped with diverse traffic with different QoS requirements, owing to the emergence of various applications in today’s communication networks. Based on the traffic requirements, packets with high-priority traffic should be served ahead of those with low-priority ones. To this end, we aim to analytically study the average end-to-end packet delay and buffer overflow performance of such a system at the granular packet level. However, packet-level queuing analysis of heterogeneous traffic is not as straightforward as that of homogeneous traffic. While considering different traffic requirements, we establish a priority queuing model for the source and the UAV nodes based on the stochastic process. Then, on the basis of the established queuing model, the average end-to-end packet delay and buffer overflow probability of the system under different trajectories are studied. Through extensive numerical simulations, we verified the accuracy and effectiveness of the proposed analytical model. The results show that the average packet delay and packet drop probability of high-priority packets under all trajectories are significantly better compared to low-priority packets. UAV trajectory has a great impact on network performance, and an appropriate mobile trajectory that takes full use of channel capacity is superior to a static one.

Multiantenna Multisource Multirelay Spectrum Sharing Networks: Buffer-Aware Direct Link Activation for Higher Reliability and Lower Overhead

Cooperative relaying can be implemented in spectrum sharing networks to extend the range of reliable communication. In this paper, we incorporate multiple-antenna technology and buffer-aided relaying to guarantee a highly reliable connectivity for the secondary network with several source nodes. The multi-antenna configuration for the sources and destination nodes suggests that there are several potential source-to-destination channels which can be auspicious for the network in two ways. First: to balance up the buffer states. Second: to expand the link selection opportunity at each time step. Motivated by this rationale, we propose a buffer-aware communication protocol to incorporate the direct transmissions along the relaying links without incurring excess overhead for circulation of channel-state-information (CSI). Considering Nakagami-m fading, we derive closed-form expressions for the end-to-end ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ete</i> ) outage probability and average packet delay of the secondary network under the proposed protocol. Through Monte-Carlo simulations, we investigate the influential network parameters and evaluate the proposed technique in comparison to two benchmark schemes, one with buffer-based link-prioritization and one without prioritization. Findings demonstrate that the proposed protocol outperforms both benchmarks in terms of outage probability and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ete</i> delay, especially as the number of nodes scales up. However, the superior performance comes at the cost of more CSI circulation. Furthermore, it is shown that if the global CSI cannot be collected accurately, then the dependency of the link selection on the global CSI should be relaxed to mitigate the performance loss. The theoretical and Monte-Carlo results coincide in several simulation examples, verifying the presented theoretical analysis.

ESMD-Flow: An intelligent flow forwarding scheme with endogenous security based on Mimic defense in space-air-ground integrated network

The Space-Air-Ground Integrated Network (SAGIN) realizes the integration of space, air, and ground networks, obtaining the global communication coverage. Software-Defined Networking (SDN) architecture in SAGIN has become a promising solution to guarantee the Quality of Service (QoS). However, the current routing algorithms mainly focus on the QoS of the service, rarely considering the security requirement of flow. To realize the secure transmission of flows in SAGIN, we propose an intelligent flow forwarding scheme with endogenous security based on Mimic Defense (ESMD-Flow). In this scheme, SDN controller will evaluate the reliability of nodes and links, isolate malicious nodes based on the reliability evaluation value, and adapt multipath routing strategy to ensure that flows are always forwarded along the most reliable multiple paths. In addition, in order to meet the security requirement of flows, we introduce the programming data plane to design a multiprotocol forwarding strategy for realizing the multiprotocol dynamic forwarding of flows. ESMD-Flow can reduce the network attack surface and improve the secure transmission capability of flows by implementing multipath routing and multi-protocol hybrid forwarding mechanism. The extensive simulations demonstrate that ESMD-Flow can significantly improve the average path reliability for routing and increase the difficulty of network eavesdropping while improving the network throughput and reducing the average packet delay.