Packet Delay Distribution Research Articles

Fault Detection Method for Wi-Fi-Based Smart Home Devices

At present, the dynamic nature and unstable network connections in the deployment environments of Wi-Fi-based smart home devices make them susceptible to component damage, crashes, network disconnections, etc. To solve these problems, researchers have used various fault detection methods, such as alarming when monitored fault parameters exceed the preset values, model-based mathematical methods, device signal processing-based methods, and artificial intelligence-based methods. However, these methods require large numbers of fault parameters, the model are complex, and their fault detection accuracy is relatively poor. To more quickly and accurately detect faults in smart home devices and ensure the continuity of people’s daily work and lives, this paper analyzes both the Wi-Fi traffic characteristics of smart home devices and the complexity and difficulty of traditional fault detection methods and proposes a fault detection method based on TDD (Throughput and Delay Distribution). This method obtains throughput and data packet delay distribution by capturing Wi-Fi communication and sending test data. By dividing the throughput into heartbeat data and command information, we can calculate the real-time throughput and further calculate the similarity between the real-time throughput and the throughput in database. Also, the resulting delay distribution is compared with the probability distribution of delay in the database. When the throughput values are sufficiently similar and the delays are all in the normal range, the smart home secure devices are functioning properly. The experimental results show that the proposed TDD method can detect faults in household devices in real time and that it achieves high recall and good detection accuracy in Wi-Fi communication environment.

Mean-Field Limits for Large-Scale Random-Access Networks

We establish mean-field limits for large-scale random-access networks with buffer dynamics and arbitrary interference graphs. Although saturated buffer scenarios have been widely investigated and yield useful throughput estimates for persistent sessions, they fail to capture the fluctuations in buffer contents over time and provide no insight in the delay performance of flows with intermittent packet arrivals. Motivated by that issue, we explore in the present paper random-access networks with buffer dynamics, where flows with empty buffers refrain from competition for the medium. The occurrence of empty buffers thus results in a complex dynamic interaction between activity states and buffer contents, which severely complicates the performance analysis. Hence, we focus on a many-sources regime where the total number of nodes grows large, which not only offers mathematical tractability but is also highly relevant with the densification of wireless networks as the Internet of Things emerges. We exploit timescale separation properties to prove that the properly scaled buffer occupancy process converges to the solution of a deterministic initial value problem and establish the existence and uniqueness of the associated fixed point. This approach simplifies the performance analysis of networks with huge numbers of nodes to a low-dimensional fixed-point calculation. For the case of a complete interference graph, we demonstrate asymptotic stability, provide a simple closed form expression for the fixed point, and prove interchange of the mean-field and steady-state limits. This yields asymptotically exact approximations for key performance metrics, in particular the stationary buffer content and packet delay distributions.

Delay analysis in the discrete‐time multi‐server queue with batch arrivals of packets having deterministic length

This work considers a discrete-time multi-server queue with batch arrivals of packets having a deterministic length. By a novel analysis, the packet delay distribution is computed with a very light computational workload.

Network Topology Inference Using Higher-Order Statistical Characteristics of End-to-End Measured Delays

Network topology is important information for many network control and management applications. Network tomography infers network topology from end-to-end measured packet delays or losses, which is more feasible than internal cooperation-based methods and attracts many studies. Most of the existing methods for network topology inference usually function under the assumption that the distribution of packet delay or loss follows a given distribution (e.g., Gaussian or Gaussian mixture), and they estimate network topology from the parameters of the given distribution. However, these methods may fail to obtain an accurate estimation because the real distribution of packet delay or loss usually cannot be described by a certain distribution. In this paper, we present a novel network topology inference method based on the unicast end-to-end measured delays. The method abandons the assumption of packet delay distribution and constructs network topology by inferring the higher-order cumulants of internal links from the end-to-end measured delays. The analytical and simulation results show that the proposed method offers over 10% improvement in accuracy compared with that of the state-of-the-art works.

Phase type delay distribution with PU return and sensing error in CR networks

Many studies have been done in cognitive radios to maximize the network efficiency. There is always a trade-off between sensing and transmission time which has been addressed fully in the literature. There is also some missed idle times during the waiting phase when secondary user finds the channel busy. Therefore, the longer the transmission time is, the higher the successfully delivered bits would be and the higher the missed idle times in the waiting stage would be expected. In this work, we formulate these missed idle times to addressed this trade-off. Furthermore, interference due to PU re-occupancy is modelled in successful transmitted time and in collision probability. Moreover, we derive secondary user’s packet delay distribution using phase type model at which retransmission due to collision results from both sensing error and PU re-occupancy is considered. Thanks to derived delay distribution, any statistical moments of delay could be found as a closed form mathematical expression. These moments can be used as constraints for applications with delay sensitive packets. Numerical results are given to clarify the network metrics. Finally, the optimized values for sensing and transmission time are computed using genetic algorithm in order to maximize access efficiency.

Packet Delay Distribution Model for Investigating Delay of Network Speech Recognition

Unlike multimedia streaming applications that require a smooth playback at the client, application of network speech recognition (NSR) that recognizes speech signal in a sentence-by-sentence manner might tolerate an acceptable delay. The acceptable delay is a user-defined time in which the entire sentence data should be received by the server. We proposed a calculation method to investigate the acceptable delay of network speech recognition that employs a speech segmenter to send speech signal sentence-by-sentence over TCP channel to the server. The calculation multiplies the mean packet delay of TCP flow at steady-state with the number of created packets. For validation we implemented a MATLAB program and solved it using 2500 Indonesian speech sentences. The results were then compared with the results of our previous model that used a transient analysis method. It was found that this calculation method is not appropriate due to the transient behavior of the streaming sentences.

Performance analysis of binary exponential backoff MAC protocol for cognitive radio in the IEEE 802.16e/m network

We propose a distributed MAC protocol for cognitive radio when primary network is IEEE 802.16e/m WiMAX. Our proposed MAC protocol is the Truncated Binary Exponential Backoff Algorithm where the backoff window size of algorithm is doubled at each collision, and the backoff counter is operated by frame basis in IEEE 802.16e/m and is freezed at a frame with no idle slots. We model our proposed MAC protocol as a 3-dimensional discrete-time Markov chain and obtain steady state probability of the Markov chain by using a censored Markov chain method. Based on this steady state probability, we obtain the throughput, packet loss probability and packet delay distribution of secondary users. Our numerical examples show that the initial contention window size can be determined according to the number of secondary users in order to obtain higher throughput for secondary users, and the maximum backoff window has a large impact on the secondary user's packet loss probability. Secondary users' packet delay distribution is much influenced by the initial contention window size and the number of secondary users.

Performance analysis of IEEE 802.15.4 superframe structure with the inactive period

We analyze the performance of IEEE 802.15.4 MAC with superframe structure including the inactive period where each device is in non-saturated conditions. The superframe structure with a inactive period has the following two primary characterizations: (i) deferment of packet transmission until the following active period due to insufficient backoff slots for completing the packet transmission, (ii) high competition in the head part of the active period due to packets which were deferred from the previous active period and were arrived during the previous inactive period. These characterizations complicate the construction of a mathematical model of MAC with the superframe structure including a inactive period. In this paper, we construct a discrete time Markov chain (DTMC) model which takes into account these characterizations. By analyzing the DTMC, we obtain the main performance measures such as throughput, packet delay distribution, packet loss probability and energy consumptions of devices and the PAN coordinator. We demonstrate high accuracy of the proposed model by comparing the numerical results with simulation results. Finally, we optimize the lengths of the beacon interval and the active period to maximize the battery life of devices while satisfying quality-of-service (QoS) constraints on packet delay and packet loss probability.

Estimation of Medium Access Control Layer Packet Delay Distribution for IEEE 802.11

The most important standard in wireless local area networks is IEEE 802.11. This is why much of the research work for the enhancement of wireless network is usually based on the behavior of IEEE 802.11 protocol. However, some of the ways in which IEEE 802.11 medium access control layer behaves is still unreliable to guarantee quality of service. For instance, medium access control layer packet delay, jitter and packet loss rate still remain a challenge. The main objective of this research is to propose an accurate estimation of the medium access control layer packet delay distribution for IEEE 802.11. This estimation considers the differences between busy probability and collision probability. These differences are employed to achieve a more accurate estimation. Finally, the proposed model and simulation are implemented and validated - using MATLAB program for the purpose of simulation, and Maple program to undertake the calculation of the equations.

Analytical Analysis of Applying Packet Fragmentation Mechanism on Both Basic and RTS/CTS Access Methods of the IEEE 802.11b DCF Network Under Imperfect Channel and Finite Load Conditions

The mathematical modeling and performance evaluation of the IEEE 802.11 network in all its various extensions (802.11b, 802.11a, 802.11g, 802.11e, 802.11n, etc.) have already been widely explored over the past years. However, the Packet Fragmentation Mechanism (PFM), which is proposed by the IEEE work group to enhance the MAC sub-layer of the IEEE 802.11 standard in an error-prone channel, has been missed in the available literature. Yet, the PFM is the only existing solution to reduce the influence of bit error rate and the length of data packets on the packet error rate, and consequently on the performances of IEEE 802.11 networks. In this paper, we propose a new three-dimensional Markov chain in order to model, for the first time in the literature, the PFM in both Basic and RTS/CTS access methods of the IEEE 802.11b DCF network under imperfect channel and finite load conditions. Then, we develop mathematical models to derive a variety of performance metrics, such as: the overall throughput, the average packet delay successfully transmitted, the average packet drop time, the delay jitter and the packet delay distribution. Performance analysis of applying PFM on both Basic and RTS/CTS access methods of the IEEE 802.11b DCF network under imperfect channel and finite load conditions shows original results and leads to new conclusions that could not be intuitively expected.

Joint delay and energy model for IEEE 802.11 networks

Popularity of IEEE 802.11 networks has increased dramatically over the past number of years. Nowadays audio/video conferencing, gaming and other quality of service (QoS) sensitive services are being delivered to the end users over wireless. Commonly probability for a packet to overstay a specific timeout serves as a QoS metric, and obtaining media access control layer packet delay distribution is highly important for this QoS prediction. Usually wireless devices are equipped with energy supplies of limited capacity, and accurate estimation of their energy expenditure is essential from the network design point of view. Meanwhile, as packets of longer delay normally have higher energy transmission cost, there is a certain dependency between the two metrics. This paper considers internal structure of the metrics and proposes a mathematical model that allows obtaining their individual distributions together with the joint distribution. The model presents a random sum, where the summand formation is determined by a Terminating Markov Process. The model has been validated through comparison with results of NS3 simulation.

Multi-parameter performance analysis for decentralized cognitive radio networks

In this paper, we investigate the impact of primary user activity, secondary user activity, interface switching, channel fading and finite-length queuing on the performance of decentralized cognitive radio networks. The individual processes of these service-disruptive effects are modeled as Markov chains based on cross-layer information locally available at the network nodes. A queuing analysis is conducted and various performance measures are derived regarding the packet loss, throughput, spectral efficiency, and packet delay distribution. Numerical results demonstrate the impact of various system parameters on the system performance, providing insights for cross-layer design and autonomous decision making in decentralized cognitive radio networks.

Quality assessment of the packet transport of peer-to-peer video traffic in high-speed networks

Dealing with the quality of the packet transport of multimedia services in overlay networks, we present the relation between the packet missing probability Pm of transmitted packets of a variable bitrate video stream and distributions of the length of the overlay path, the upload capacity of nodes and the playback delay at a destination node. As active streams share the capacity of a transport channel, we select an equivalent bandwidth based on a bufferless fluid-flow model. A smallest equivalent capacity u∗ which provides the best trade-off between the mean delay between successfully delivered packets and the mean lossless time that is determined by the duration of consecutive successful packet transmissions is proposed as an optimal upload capacity. u∗ is less than the peak rate. The playback delay b is selected as a quantile of a packet delay distribution. The normalized distribution of the length of the overlay path is derived to be geometric. The estimation of u∗ and b requires inter-arrival times between packets, packet lengths of a peer-to-peer video flow and end-to-end packet delays. For SopCast IPTV data it is concluded that the signaling traffic does not impact on u∗ and increasing b leads to the decrease of Pm.

Packet-Level Performance Analysis for Video Traffic over Two-Hop Mobile Hotspots

Focusing on the uplink video transmission over a two-hop mobile network, we analyze the video performance in terms of packet loss probability and packet delay distribution. The burst arrival nature and strong correlation of video traffic are taken into account by using a discrete-time batch Markovian arrival process. The impact of packet transmissions between the two hops is investigated by properly modelling the packet departure process of the first hop. To address a strict delay constraint for video services, we consider a buffer size limit in the first hop and a proactive packet discard policy in the second hop. Numerical results based on video traces demonstrate the effectiveness of the proposed analytical approach.

Delaying Transmissions in Data Communication Networks to Improve Transport-Layer Performance

Packet losses in the network have a considerable performance impact on transport-layer throughput. For reliable data transfer, lost packets require retransmissions and thus cause very long delays. This tail of the packet delay distribution causes performance problems. There are several approaches to trading off networking resources up-front to reduce long delays for some packets (e.g., forward error correction, network coding). We propose packet pacing as an alternative that changes traffic characteristics favorably by adding intentional delay in packet transmissions. This intentional delay counters the principle of best effort but can reduce the burstiness of traffic and improve overall network operation - in particular in network with small packet buffers. As a result, pacing improves transport-layer performance, providing a tradeoff example where small amounts of additional delay can significantly increase connection bandwidth. We present a Queue Length Based Pacing (QLBP) algorithm that paces network traffic using a single queue and that can be implemented with small computational and memory overhead. We present a detailed analysis on delay bounds and the quantitative impact of QLBP pacing on network traffic. Through simulation, we show how the proposed pacing technique can improve connection throughput in small-buffer networks.

Virtually Dedicated Resource Allocation for VoIP Traffic in the Downlink Mobile WiMAX System With Hybrid ARQ

This paper introduces the concept of a virtually dedicated resource allocation (VDRA) scheme that significantly reduces signaling overhead for accommodating low/medium data traffic, including real-time VoIP traffic. The basic concept of the VDRA scheme is to allocate the virtually dedicated resource to each user and to use the resource only when there are data to be transmitted. The performance of the proposed VDRA scheme in downlink is analyzed using a queuing system with hybrid automatic repeat request retransmissions to derive the distribution of packet delay and user capacity. In addition, the analytical results are verified through simulation results. The performance of the proposed VDRA scheme is compared with the persistent allocation scheme and the dynamic scheduling scheme. The proposed VDRA scheme yields a 15%-28% increase in user capacity and a 26%-69% decrease in the size of signaling overhead compared with the dynamic scheduling scheme. The proposed VDRA scheme yields slightly better performance in terms of user capacity and signaling overhead than the persistent allocation scheme for accommodating even voice over Internet Protocol (VoIP) traffic. In addition, the proposed VDRA scheme yields much smaller mean packet delay performance than the persistent allocation scheme. Moreover, the application of the persistent allocation (PA) scheme is limited to only real-time periodic VoIP traffic. On the other hand, the applicability of the proposed VDRA scheme is much wider than the PA scheme, including periodic and nonperiodic traffic, as well as real-time and non-real-time traffic, because the proposed VDRA scheme requires no constraint to the input traffic.

Throughput and Latency in Finite-Buffer Line Networks

This work investigates the effect of finite buffer sizes on the throughput capacity and packet delay of line networks with packet erasure links that have perfect feedback. These performance measures are shown to be linked to the stationary distribution of an underlying irreducible Markov chain that models the system exactly. Using simple strategies, bounds on the throughput capacity are derived. The work then presents two iterative schemes to approximate the steady-state distribution of node occupancies by decoupling the chain to smaller queueing blocks. These approximate solutions are used to understand the effect of buffer sizes on throughput capacity and the distribution of packet delay. Using the exact modeling for line networks, it is shown that the throughput capacity is unaltered in the absence of hop-by-hop feedback provided packet-level network coding is allowed. Finally, using simulations, it is confirmed that the proposed framework yields accurate estimates of the throughput capacity and delay distribution and captures the vital trends and tradeoffs in these networks.

A study of on/off timing channel based on packet delay distribution

An on/off timing channel is a typical network covert timing channel, which can be used by attackers to steal information from compromised systems without triggering network firewalls and intrusion detection systems. In this paper, we discuss the principle of the information transmission in an on/off timing channel and categorize such channels into two types: deterministic channels and non-deterministic channels. We then analyze the components of packet delay and their characteristics, and provide a method of calculating the maximum transmission rate of a non-deterministic channel based on the packet delay distribution. After that, we conduct experiments to obtain the packet delay distribution in real network, and calculate the maximum transmission rate via our method. Then we construct an actual channel, and attain the actual transmission rate based on the observed symbol transmission probabilities. Our experiments show that the transmission rate calculated through our method is close to the real one, and can reveal the risk of the information leakage via on/off time channels in a network. In addition, the results indicate that non-deterministic channels may bring more threat than deterministic ones in the same network, and the information leakage via on/off timing channels should gain more intention.

Queuing Delay Analysis for Packet Schedulers With/Without Multiuser Diversity Over a Fading Channel

In this paper, we focus on a packet scheduling algorithm exploiting multiuser diversity in wireless networks. We compare the delay performance of the individual user under the scheduling algorithm exploiting multiuser diversity with that under the round-robin (RR) scheduling algorithm in order to reveal the characteristics of the scheduling algorithm exploiting multiuser diversity. For this purpose, we develop an approximate formula to estimate the tail distribution of packet delay for an arbitrary user under the scheduling algorithm exploiting multiuser diversity and under the RR scheduling algorithm. Numerical results exhibit that, in contrast to the throughput performance of the overall system, the scheduling algorithm exploiting multiuser diversity is not necessarily superior to the RR scheduling algorithm for the delay performance of the individual user. More specifically, it is shown that the former is superior to the latter only when the system lies in a severe environment, e.g., when the arrival rate is large, the burstiness of the arrival process is strong, or the average signal-to-noise ratio is low.

A Proposal for Service Differentiation by a Link Layer Protocol Based on SR ARQ and Its Evaluation

This paper studies the situation where multiple IP flows are aggregated over a single wireless channel and an error recovery by retransmissions is performed by Selective-Repeat (SR) ARQ. We propose MQ-PFRS (Multi-QoS Per-Flow Resequencing) ARQ that provides a differentiated service for an IP flow depending on its QoS class, such as real-time or non-real-time. MQ-PFRS ARQ eliminates interferences among IP flows by resequencing received packets independently for each IP flow. It also controls the maximum packet delay by limiting the persistency of retransmissions and the maximum resequencing time for each packet. This paper also presents an analysis of the probability distribution of real-time packet delays. Simulation results show that the delay variation of real-time traffic is effectively controlled by proposed MQ-PFRS ARQ and the packet delay distribution is quite consistent with the results of the analysis. This means that MQ-PFRS is effective for handling multiple QoS classes of IP flows and the quality of real-time traffic transferred by the scheme can be predicted by the analysis.