Node Buffer Research Articles

Adaptation with transcriptional regulation

Biochemical adaptation is one of the basic functions that are widely implemented in biological systems for a variety of purposes such as signal sensing, stress response and homeostasis. The adaptation time scales span from milliseconds to days, involving different regulatory machineries in different processes. The adaptive networks with enzymatic regulation (ERNs) have been investigated in detail. But it remains unclear if and how other forms of regulation will impact the network topology and other features of the function. Here, we systematically studied three-node transcriptional regulatory networks (TRNs), with three different types of gene regulation logics. We found that the topologies of adaptive gene regulatory networks can still be grouped into two general classes: negative feedback loop (NFBL) and incoherent feed-forward loop (IFFL), but with some distinct topological features comparing to the enzymatic networks. Specifically, an auto-activation loop on the buffer node is necessary for the NFBL class. For IFFL class, the control node can be either a proportional node or an inversely-proportional node. Furthermore, the tunability of adaptive behavior differs between TRNs and ERNs. Our findings highlight the role of regulation forms in network topology, implementation and dynamics.

Improved Utility-Based Congestion Control for Delay-Constrained Communication

Due to the presence of buffers in the inner network nodes, each congestion event leads to buffer queueing and thus to an increasing end-to-end delay. In the case of delay sensitive applications, a large delay might not be acceptable and a solution to properly manage congestion events while maintaining a low end-to-end delay is required. Delay-based congestion algorithms are a viable solution as they target to limit the experienced end-to-end delay. Unfortunately, they do not perform well when sharing the bandwidth with congestion control algorithms not regulated by delay constraints (e.g., loss-based algorithms). Our target is to fill this gap, proposing a novel congestion control algorithm for delay-constrained communication over best effort packet switched networks. The proposed algorithm is able to maintain a bounded queueing delay when competing with other delay-based flows, and avoid starvation when competing with loss-based flows. We adopt the well-known price-based distributed mechanism as congestion control, but: 1) we introduce a novel non-linear mapping between the experienced delay and the price function and 2) we combine both delay and loss information into a single price term based on packet interarrival measurements. We then provide a stability analysis for our novel algorithm and we show its performance in the simulation results carried out in the NS3 framework. Simulation results demonstrate that the proposed algorithm is able to: achieve good intra-protocol fairness properties, control efficiently the end-to-end delay, and finally, protect the flow from starvation when other flows cause the queuing delay to grow excessively.

基于Geom/G/1模型的Ad Hoc网络节点性能分析

本文将网络中的每一个节点看作一个排队系统，基于Geom/G/1排队模型给出了缓存器中排队分组的平均队长，并利用Little定理得到分组的等待时延。通过计算发送一个分组的平均开销，进而得到了信道的平均利用率的计算方法，并将该方法应用到Ad Hoc网络中，得到了Ad Hoc网络的开销和信道利用率。 In this paper, we consider each node in the network as a queuing system. Based on the Geom/G/1 queuing model, we give the average queue length in the buffer of node, and use the Little theorem to get the waiting delay of the packet. By calculating the average overhead of sending a packet, the method of calculating the average utilization of the channel is obtained, and which is applied to obtain the overhead and channel utilization of the Ad Hoc network.

A* search based next hop selection for routing in opportunistic networks

Opportunistic network (oppnet) is one of the challenging fields of wireless network. It is an intermittently connected mobile network where nodes are mobile and no end-to-end path exists. Connectivity among nodes is established when they are within the transmission range of each other. If a node has message to communicate and no intermediate node is available, then the message is stored in the node's buffer till an appropriate communication opportunity arises which is known as store-carry-forward paradigm. This paradigm has given Oppnets a new direction in the field of research. In any network, efficient and effective routing is very crucial. In this paper, a novel routing technique has been proposed for Oppnets named as A* based opportunistic routing (A*OR) which uses the A* searching technique to select the best forwarders towards the destination. The proposed protocol is compared with prophet, PRoWait and EDR as a benchmark protocols and is found to perform 19%, 11% and 32% better than prophet, PRoWait and EDR, respectively in terms of delivery probability.

A* search based next hop selection for routing in opportunistic networks

Opportunistic network (oppnet) is one of the challenging fields of wireless network. It is an intermittently connected mobile network where nodes are mobile and no end-to-end path exists. Connectivity among nodes is established when they are within the transmission range of each other. If a node has message to communicate and no intermediate node is available, then the message is stored in the node's buffer till an appropriate communication opportunity arises which is known as store-carry-forward paradigm. This paradigm has given Oppnets a new direction in the field of research. In any network, efficient and effective routing is very crucial. In this paper, a novel routing technique has been proposed for Oppnets named as A* based opportunistic routing (A*OR) which uses the A* searching technique to select the best forwarders towards the destination. The proposed protocol is compared with prophet, PRoWait and EDR as a benchmark protocols and is found to perform 19%, 11% and 32% better than prophet, PRoWait and EDR, respectively in terms of delivery probability.

Mitigation of Packet Loss Using Data Rate Adaptation Scheme in MANETs

Node’s mobility, bursty data traffic, and dynamic nature of the network make congestion avoidance and control a challenging task in Mobile Adhoc Networks (MANETs). Congestion results in high packet loss rate, increased delays, and wastage of network resources due to re-transmissions. In this paper, we propose In-route data rate adaptation to avoid packet loss. Proposed scheme is based on the analysis of queue length of the forwarding nodes, number of data source nodes, and rate of link changes. In proposed technique, queue length of forwarding nodes is communicated periodically to the neighbor nodes using existing control messages of the underlying routing protocol. Keeping in view the queue length of forwarding nodes, number of data source nodes, and rate of link changes, initially the intermediate nodes buffer the incoming data packets upto some threshold and then, gradually shift the effect of congestion to the data source nodes. Then, the source node adapts its sending data rate to avoid congestion and to ensure reliable data communication. We have performed simulations in NS-2 simulator by varying different network metrics such as data rate, number of source nodes, and node speed. Results show that proposed technique improves network performance in terms of packet delivery ratio upto 15 %, reduction of average end-to-end delay and packet loss due to interface queue overflow upto 25 % and 14 % respectively, as compared to the static rate adaptation scheme.

Replica Node Detection in Static Wireless Sensor Networks using Neighborhood Information

This study proposes a novel, simple, and efficient algorithm using explorer nodes to overcome the replica node attack in static wireless sensor networks. In the replica node attack, the adversary captures a legitimate node in the network and extracts its important information, including its ID, to generate and inject several replica nodes in the network. These nodes are controlled by the adversary and have the ability to link legitimate nodes. Therefore, these replica nodes can easily have their corruptive impacts on network integrity. The main notion of the proposed algorithm is to collect spatial and neighborhood information by mobile explorer nodes in the network environment to detect replica nodes. The proposed algorithm consists of two parts: 1recording information in the buffer of explorer nodes, and 2verifying buffer content to detect potential replica nodes. The proposed algorithm is implemented and its efficiency is evaluated by a set of experiments in terms of replica node detection rate. Furthermore, evaluation results are compared with existing algorithms and indicate that the proposed algorithm outperforms other methods.

A method of approximate analysis of an open exponential queuing network with losses due to finite shared buffers in multi-queue nodes

We consider a model of an open exponential queuing network where each node comprises several multi-class MR/M/1 queues that share a common waiting space (a buffer) of limited capacity. A customer arriving to a node with fully occupied buffer is lost. An assumption is made that each class input traffic to a node, which is a superposition of the class external Poisson flow and the class flows coming from other nodes, is a Poisson process. Under this assumption a method of an approximate analysis is presented. It is based on solving iteratively a system of non-linear equations for the unknown nodal flow rates. It is shown that the gradient iterations solve the multi-class network equations. For the single-class model we use the direct substitution iterations. In the latter case existence and uniqueness of the solution, obtained by the iterative algorithm, is rigorously proven. It is demonstrated for a few network configurations that the network and node performance characteristics received by analytic approach are close to those obtained by simulation method. Our contribution is a performance evaluation methodology that could be usefully employed in queuing network design.

A Congestion Avoidance Scheme based on modules of Energy harvesting Sensor Networks

In this paper, We propose a congestion avoidance scheme based on modules to avoid congestion according to various congestion states and energy of sensor nodes on energy harvesting sensor networks. Proposed Scheme is guaranteed confidentiality and integrity in security. Proposed scheme can avoid various congestion according to congestion avoidance modules, which defined energy harvesting states and various estimated congestion. This congestion avoidance modules consist of a differentiated rate control scheme and a selective rate control scheme control differentially sending rate of all sensor node or selective sensor nodes according to their transmission distance. To evaluate a performance of proposed scheme, we simulate the number of lost packet, the amount of packets in a buffer of a sink node, the number of sending packets of sensor nodes. In the results of simulation, proposed scheme is superior to compared scheme.

Cooperative mechanism for PNC two-hop slotted ALOHA network

In this paper, we propose a buffer-information-aided (BIA) request to send (RTS)/clear to send (CTS) mechanism to improve the throughput performance of physical-layer network coding (PNC) in a slotted-ALOHA two-hop relay network. In the proposed BIA mechanism, the relay node collects the information of the destination address of the first several packets at the sending buffers of the client nodes, and determines the transmission client nodes at the next time slot. Therefore, the collision probability can be decreased and the proportion of PNC transmissions among the total transmissions is improved. Simulation results show that compared with the traditional RTS/CTS mechanism, the proposed cooperative mechanism can greatly improve the PNC network throughput.

Globally Stable Wireless Data Flow Control

Packet data flow control from internet nodes to wireless transmission nodes will become increasingly important in 5G wireless systems. One reason is the new requirement to maintain and guarantee a maximum round-trip loop delay for high-bandwidth feedback control applications. Another driver is the emerging multipoint mobile broadband internet access, where data starvation needs to be avoided in the transmit queue buffers of the wireless transmission nodes. Moreover, robust global stability is a requirement, since an only locally stable data flow controller would have a nonzero likelihood to malfunction algorithmically. The resulting networked control problem is further complicated by an uncertain internet backhaul loop delay, in combination with a one-directional data flow that introduces saturation in the feedback loop. The paper therefore contributes with a proof of global robust stability for a nonlinear networked window-based packet flow control algorithm. The performance and stability of the controller are assessed with simulation, which shows that the algorithm performs as required.

MaxHopCount: A New Drop Policy to Optimize Messages Delivery Rate in Delay Tolerant Networks

Communication has become a necessity, not only between every point on the earth, but also on the globe. That includes hard topography, highlands, underwater areas, and also space- crafts on other planets. However, the classic wired internet cannot be implemented in such areas, hence, researchers have invented wireless networks. The big challenge for wireless networking nowadays, is maintaining nodes connected in some difficult conditions, such as intermittent connectivity, power failure, and lot of obstacles for the interplanetary networks. In these challenging circumstances, a new networking model arises; it is Delay Tolerant networking which is based on the Store-Carry-and-Forward mechanism. Thus, a node may keep a message in its buffer for long periods of time; until a delivery or forward chance arises then it transmit it to other nodes. One of the big issues that confront this mechanism is the congestion of nodes buffer due to the big number of messages and the limited buffer size. Here, researchers have proposed buffer management algorithms in order to deal with the buffer overload problem, and they called it Drop Policies. In our present work, we propose a new Drop policy which we have compared to other existing policies in different conditions and with different routing protocols, and it always shows good result in term of number of delivered messages, network overhead and also average of latency.

Reduced-Packet-Delay Generalized Buffer-Aided Relaying Protocol: Simultaneous Activation of Multiple Source-to-Relay Links

Motivated by the recent buffer-aided relaying protocol that selects the best available link at each time slot, we herein introduce an additional degree of freedom to the protocol by simultaneously exploiting multiple links between the source node and the multiple buffer-aided relay nodes, which is enabled owing to the broadcast nature of wireless channels. More specifically, the proposed schemes are designed to allow multiple relay nodes to receive a source packet through source-to-relay broadcast channels, resulting in multiple copies of the source packet, which are stored in relay node buffers. As the explicit benefits of its increased design degree of freedom, the proposed protocols attain a significantly lower end-to-end packet delay than the conventional buffer-aided relaying protocols, which is achieved without imposing any substantial penalty on the achievable outage probability. Furthermore, the proposed protocol is capable of reducing the overhead required for monitoring the available links and buffer statuses of the relay nodes. Based on the Markov chain model, we derive the theoretical bounds of the outage probabilities of the proposed protocols.

On Demand Priority Packet Forwarding for TCP Performance Enhancement in Cognitive Mobile IP Networks

Spectrum mobility packet drops due to dynamic channel handover in optimized cognitive mobile IP leads to end-to-end connection disruption and severe performance degradation in transmission control protocol (TCP). In traditional mobile IP, buffered packet drops in between base station and the mobile node are only due to node mobility and network congestion. To date, number of packet buffering and forwarding mechanisms were proposed to reduce the node mobility and buffer overflow packet drops. But, dynamic spectrum access in cognitive mobile IP introduces spectrum mobility packet drops apart from node mobility and network congestion. Hence, it is significant to enhance the existing mobile IP to support the spectrum handover framework and reduce spectrum mobility packet drops during primary user (PU) active in the current cognitive radio channel. In this work, on-demand priority packet forwarding with spectrum handover support is proposed to reduce the packet drops due to spectrum mobility, node mobility and network congestion. In addition, adaptive power control algorithm is proposed to reduce the collisions due to hidden PU receivers at edge PU coverage area. Experimental results disclose that the performance of TCP with proposed on-demand priority packet forwarding outperforms the existing packet buffering mechanisms.

Characterisation of the output process of a discrete-time GI / D / 1 queue, and its application to network performance

In this paper we use the burst factor of a packet stream, which is defined in a general setting, to quantify the long-term variability, or burstiness, of such a stream. We briefly review some existing results to show that this parameter plays an important role in the performance assessment and dimensioning of buffers in network nodes, even in a non-Markovian setting. We then focus on the calculation of this parameter at the egress of a discrete-time GI / D / 1 queueing system, considering different routing scenarios, and show how it can be expressed in terms of the parameters that characterise the arrival process in such a queue. In addition, we demonstrate how these results can be applied to evaluate the buffer performance in the subsequent nodes of a network. The analytic results that are derived throughout this paper are supported by simulations.

À Load-balancing and Self-adaptation Clustering for Lifetime Prolonging in Large Scale Wireless Sensor Networks

Abstract Hierarchical routing is an efficient way to lower energy consumption within a cluster, performing data aggregation and fusion in order decrease the number of transmitted messages to the BS. In this paper, a novel hierarchical approach called distributed energy efficient adaptive clustering protocol with gathering data (DEACP) is proposed for Wireless sensor network. Since nodes in a sensor network have limited energy, prolonging the network lifetime and improving scalability become important. we have proposed (DEACP) approach to reach the following objectives: reduce the overall network energy consumption, balance the energy consumption among the sensors and extend the lifetime of the network, the clustering must be completely distributed, the clustering should be efficient in complexity of message and time, the cluster-heads should be well-distributed across the network, the load balancing should be done well, the clustered WSN should be fully-connected. As a result transmission power of the node is reduce which subsequently reduces the energy consumption of the node. Our proposed work is simulated through Network Simulator (NS-2). We consider the problem of conserving energy in a single node in a wireless sensor network by turning off the node's radio for periods of a fixed time length. While packets may continue to arrive at the node's buffer during the sleep periods, the node cannot transmit them until it wakes up. The objective is to design sleep control laws that minimize the expected value of a cost function representing both energy consumption costs and holding costs for backlogged packets. The resource reservation is used to decompose the total simulation time of network into smaller time slots depending upon number of nodes in the network using TDMA technique. Simulations show that (DEACP) clusters have good performance characteristics.

Effect of Transmission Control Protocol on Limited Buffer Cognitive Radio Relay Node

Transmission Control Protocol (TCP) is the most important transport layer protocol being used nowadays. It suffers from many problems over mobile networks especially over Cognitive Radio (CR). CR is one of the latest mobile technologies that brings its own share of problems for TCP. The buffer overflow for CR secondary network relay node can affect the performance of TCP. The contribution of this paper is the novel cross-layer model being used to evaluate the effect of the TCP congestion control on the secondary relay node buffer size in Cognitive Radio Network (CRN). The performance has been assessed by buffer overflow probability.

Hybrid Algorithm to Control Congestion in Wireless Sensor Networks

The Congestion in wireless sensor networks occurs when packets arrive at a fully loaded buffer of a sensor node. Due to lack of space in the buffer, packets are dropped. It also leads to packet delay, retransmission of packets, reduced QoS and throughput. A hybrid of rate control and resource control algorithms can be used to control congestion considering the priority of the packets. Congestion is detected when the service time is greater than the interarrival time of packets. The inter-arrival time can be increased by a certain factor computed as congestion degree, thus reducing the rate of sending packets. The congestion degree which is the ratio of service time to inter-arrival time can be sent to the sources. The sources can then adjust the rate of sending packets accordingly to control congestion in the upstream nodes. At the time of congestion, high priority packets are sent using multiple paths after increasing the time between generations of packets thus decreasing the rate of sending packets. Low priority packets are sent using a single path after decreasing the packet sending rate thus increasing the time between sending consecutive packets. The method also serves as a hybrid of congestion control and congestion avoidance.

Enhanced fuzzy logic‐based spray and wait routing protocol for delay tolerant networks

SummaryDelay tolerant networks are a class of ad hoc networks that enable data delivery even in the absence of end‐to‐end connectivity between nodes, which is the basic assumption for routing in ad hoc networks. Nodes in these networks work on store‐carry and forward paradigm. In addition, such networks make use of message replication as a strategy to increase the possibility of messages reaching their destination. As contact opportunities are usually of short duration, it is important to prioritize scheduling of messages. Message replication may also lead to buffer congestion. Hence, buffer management is an important issue that greatly affects the performance of routing protocols in delay tolerant networks. In this paper, Spray and Wait routing protocol, which is a popular controlled replication‐based protocol for delay tolerant networks, has been enhanced using a new fuzzy‐based buffer management strategy Enhanced Fuzzy Spray and Wait Routing, with the aim to achieve increased delivery ratio and reduced overhead ratio. It aggregates three important message properties namely number of replicas of a message, its size, and remaining time‐to‐live, using fuzzy logic to determine the message priority, which denotes its importance with respect to other messages stored in a node's buffer. It then intelligently selects messages to schedule when a contact opportunity occurs. Because determination of number of replicas of a message in the network is a difficult task, a new method for estimation of the same has been proposed. Simulation results show improved performance of enhanced fuzzy spray and wait routing in terms of delivery ratio and resource consumption. Copyright © 2014 John Wiley & Sons, Ltd.

On the packet loss overhead in buffer-limited ad hoc networks

This paper focuses on the routing overhead analysis in ad hoc networks. Available work in this research field considered the infinite buffer scenario, so that buffer overflow will never occur. Obviously, in realistic ad hoc networks, the node buffer size is strictly bounded, which leads to unavoidable packet loss. Once a packet is dropped by a relay node, the bandwidth consumption for the previous transmission is actually wasted. We define the extra wasted bandwidth as the packet loss (PL) overhead. A theoretical analysis framework based on G/G/1/K queuing model is provided, to estimate the PL overhead for any specific routing protocols. Then, with this framework, we propose a distributed routing algorithm termed as novel load-balancing cognitive routing (NLBCR). The OPNET network simulator is further conducted to compare the performance among the NLBCR, AODV and CRP. The results indicate that NLBCR can reduce routing overhead to a considerable extent, as well as improve the network throughput and decrease the end-to-end delay.