Mean Packet Research Articles

CSMA-Based Utility-Optimal Scheduling in the WLAN With a Full-Duplex Access Point

Full-duplex wireless communication has been recognized as an effective technique to improve the system throughput. This paper designs a CSMA-based utility-optimal scheduling scheme to fully explore the performance improvement brought by AP’s full-duplex capability. In particular, to keep the backwards compatibility of the legacy users, we allow users to compete to access the channel using the CSMA protocol in their uplink transmissions while let the AP select its downlink user to communicate with for completing the full-duplex transmission upon each uplink access. Moreover, to achieve the optimal system utility, we then formulate an optimization problem of maximizing the downlink aggregate utility subject to the uplink users’ data rate constraints. The formulated problem falls into a mixed integer nonlinear programming form, which is generally NP-hard to solve. To make the problem tractable, we divide it into user pairing and access-intensity adjustment subproblems. More specifically, we devise a user pairing criterion based on the signal-to-interference-plus-noise ratio to reduce the uplink-downlink interference, and adopt the Hungarian algorithm to find the best matching between uplink and downlink users. After that, we adjust the access-intensity of users (i.e., the ratio of the mean packet transmission time to the mean backoff time) to maximize the downlink aggregate utility based on the geometric programming. Simulation results are presented to evaluate the performance of our scheduling design and demonstrate the downlink aggregate utility improvement compared to other scheduling schemes in full-duplex WLANs.

Design and Analysis of Traffic-Based Discontinuous Reception Operations for LTE Systems

The 3GPP long term evolution (LTE) system is developed to enhance mobile services from the former 3G systems. In order to prolong the battery life time of mobile devices, the discontinuous reception (DRX) scheme is specified in the LTE standard to reduce the power consumption of user equipment. Existing analytical models did not comprehensively consider all essential sleep mode behaviors. Therefore, a performance analysis, including major DRX parameters is proposed in this paper for sleep mode operation. The correctness of proposed model is validated and the improvement can be observed via simulations. Furthermore, according to proposed analytical model, the DRX parameters can significantly influence the power-saving efficiency and quality-of-service (QoS) of LTE system. Hence, a traffic-based DRX cycles adjustment (TDCA) scheme is proposed to adaptively adjust the sleep cycles to balance the sleep ratio and mean packet delay based on traffic estimation. A partially observable Markov decision process is employed to conjecture the present traffic status. The policy for selecting DRX parameters can be constructed-based the evaluation metrics in TDCA scheme. Simulation results show that the proposed TDCA scheme can enhance the energy-saving efficiency while the QoS constraint is still satisfied.

OLT Energy Savings via Software-Defined Dynamic Resource Provisioning in TWDM-PONs

Time and wavelength division multiplexed passive optical network (TWDM-PON) standards dramatically increase the performance of PON systems and address ever-increasing demands for bandwidth. However, these schemes increase the complexity and energy consumption of PON systems because they exploit multiple wavelengths, which requires multiple transceivers in the optical line terminal (OLT). In this paper, we propose to integrate software-defined networking (SDN) into standard PON architectures to facilitate an orchestrated energy-efficient operation in which the SDN controller dynamically provisions the number of wavelengths, link-rates, and timeslot assignments depending on the global traffic conditions. The simulation results show that the proposed architecture and mechanism improves the energy-saving performance of OLTs if the traffic load is less than 80%, while guaranteeing the quality of service requirements in terms of the mean packet delay, jitter, queue length, throughput, and packet loss ratio.

Performance Evaluation of Cognitive Radio VoIP Users in Fading Environment

In this paper we investigate three channel allocation algorithms for multi-channel cognitive radio networks: SNR-based allocation (SA), queue-based allocation (QA), and queue-based SNR-aware allocation (QSA). The efficiency of the proposed algorithms is investigated for VoIP cognitive radio users (CRs). The resource allocation in the SA and QA schemes is performed based on the channel quality status seen by each CR and its queue length, respectively. The channel allocation in the QSA scheme is based on both the queue length and the SNR status. The mean packet loss rate (PLR) as the main quality-of-service (QoS) parameter is scrutinized for each algorithm. Novel analytical structures together with new analyses are developed, by which the level of provisioning QoS of VoIP traffic in each of the proposed algorithms can be evaluated. Numerical results and comparisons are also presented. In particular, the QSA algorithm is shown to present the best QoS level and yield the least PLR among the three allocation schemes.

Delay-Optimal Biased User Association in Heterogeneous Networks

In heterogeneous networks (HetNets), load balancing among different tiers can be effectively achieved by a biased user association scheme with which each user chooses to associate with one base station (BS) based on the biased received power. In contrast to previous studies, where a BS always has packets to transmit, we assume in this paper that incoming packets intended for all the associated users form a queue in the BS. In order to find the delay limit of the network to support real-time service, we focus on the delay optimization problem by properly tuning the biasing factor of each tier. By adopting a thinned Poisson point process model to characterize the locations of BSs in the busy state, an explicit expression of the average traffic intensity of each tier is obtained. On that basis, an optimization problem is formulated to minimize a lower bound of the network mean queuing delay. By showing that the optimization problem is convex, the optimal biasing factor of each tier can be obtained numerically. When the mean packet arrival rate of each user is small, a closed-form solution is derived. The simulation results demonstrate that the network queuing performance can be significantly improved by properly tuning the biasing factor. It is further shown that the network mean queuing delay might be improved at the cost of a deterioration of the network signal-to-interference ratio coverage, which indicates a performance tradeoff between real-time and non-real-time traffic in HetNets.

TRAFFIC DESIGN MODEL FOR OPTIMUM PERFORMANCE ENHANCEMENTS OF IEEE 802.11B QOS PARAMETERS

Purpose: The objective of this research is to design a traffic model for optimum performance analysis and enhancements of IEEE 802.11b QOS parameters. It investigated the effect of traffic distribution on the quality of service parameter on WLAN, in other to establish enhanced WLAN Performance. In order to evaluate the mean packet delay and network throughput performance, this research has presented a traffic loading for MAC DCF which supports WLAN’s QOS Parameters.Methodology: Based on this model, a computer simulation model over a MATLAB Simulink was developed.Results: In this research, results show that the IEEE 802.11b does not perform well in terms of high throughput, and low mean delay at high traffic load conditions. Furthermore, it was also shown that the mean packet delay of arrived packets decreases as the number of workstations decreases, but at saturation, it was shown that throughput decreases, mean packet delay increases. Therefore, to achieve a better enhanced network performance, it was observed that IEEE 802.11b WLAN QOS parameters can be improved to a maximum throughput.

Optimal Resource Allocation for Packet Delay Minimization in Multi-Layer UAV Networks

Research and development of heterogeneous small cell in cellular network accommodates the proliferation of data-hungry devices and applications. Meanwhile, for challenges in providing high-data-rate transmission in poor coverage area, utilizing unmanned aerial vehicles (UAVs) provides a promising solution attracting tremendous attention. However, tight integration of UAVs creates an obstruction in existing network to acquire high efficient resource utilization, which needs investigation in 3 D network architecture. In this letter, we propose a resource allocation optimization mechanism to minimize mean packet transmission delay in 3 D cellular network with multi-layer UAVs. Numerical results demonstrate effectiveness of the proposed algorithm, where optimal spectrum and power allocation can provide minimum packet transmission delay.

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.

Decentralization for Securing Data with Cloud Firewall Framework to Increase QoS

Objectives: To implement the cloud decentralized firewall concept. Methods/Statistical Analysis: A balanced approach is always needed while satisfying the user’s need and at the same time the Quality of Service (QoS) is to increase. The solution could be in allocating the resource dynamically to handle the multiple users and to optimize the cost of the resource provision. Mostly, queuing theory is used for quantitative system analyze. Markov Chain and Z-transform is used to obtain the mean packet in the response time to closed form of expression. Findings: The M/M/1 model is our proposed M/Geo/1 model for better firewall real system. The experimental results also prove that we can set up the firewall in cloud with comfortable cost to cloud users.

QoS-Oriented Mode, Spectrum, and Power Allocation for D2D Communication Underlaying LTE-A Network

This paper investigates the problem of resource allocation for device-to-device (D2D) communication in a Third-Generation Partnership Project (3GPP) Long-Term Evolution Advanced (LTE-A) network. The users in the network can operate either in a traditional cellular mode, communicating with each other via the evolved NodeB (eNB), or in a D2D mode, communicating with each other without traversing the eNB. In the considered model, the D2D users and cellular users share the same radio resources. Particularly, each resource block (RB) within the available bandwidth can be occupied by one cellular and several D2D users. Hence, the problem of interference management is crucial for effective performance of such a network. The twofold aim of the proposed algorithm is to 1) mitigate the interference between cellular and D2D users and 2) improve the overall user-perceived quality of service (QoS). To control the interference, for each user, we define a certain target interference level and constrain the interference from the other users to stay below this level. The corresponding optimization problem maximizes the QoS of the users by minimizing the size of the buffers of user equipments (UEs). The performance of the algorithm has been evaluated by using the OPNET-based simulations. The algorithm shows improved performance in terms of mean packet end-to-end delay and loss for UEs when compared to other relevant schemes.

Optimized design of delay-line buffers with an input-feedback mechanism for asynchronous optical packet switching networks.

The delay-line buffer is widely used to solve contention by exploiting the time domain for optical packet switching (OPS) networks. How to optimize the length of the delay-line element to minimize the packet loss is a major challenge in designing delay-line buffers efficiently. In this paper we consider the buffers in asynchronous OPS networks with different incoming traffic patterns. For a specific mean packet length, we first demonstrate that the optimum length value of the delay-line element mainly depends on the incoming traffic load. The dependence of packet loss ratio on the delay-line granularity under different traffic loads and buffer sizes is given by both analytical model and simulation results. An optimum delay granularity is found under each traffic load, and this optimum granularity is independent of the buffer sizes. According to this finding, we designed an adaptive delay-line buffer structure with an input-feedback mechanism, namely an improved multiple-input single-output optical buffer, which could automatically configure the switch fabric and adjust the delay-line granularity according to the incoming traffic load. It is shown that the proposed buffer structure can achieve optimum performance for packet loss rate under different network scenarios.

A high-throughput energy-efficient passive optical datacenter network

Datacenter applications impose heavy demands on bandwidth and also generate a variety of communication patterns (unicast, multicast, incast, and broadcast). Supporting such traffic demands leads to networks built with exorbitant facility costs and formidable power consumption if conventional design is followed. In this paper, we propose a novel high-throughput datacenter network that leverages passive optical technologies to efficiently support communications with mixed traffic patterns. Our network enables a dynamic traffic allocation that caters to diverse communication patterns at low power consumption. Specifically, our proposed network consists of two optical planes, each optimized for specific traffic patterns. We compare the proposed network with its optical and electronic counterparts and highlight its potential benefits in terms of facility costs and power consumption reductions. To avoid frame collisions, a high-efficiency distributed protocol is designed to dynamically distribute traffic between the two optical planes. Moreover, we formulate the scheduling process as a mixed integer programming problem and design three greedy heuristic algorithms. Finally, simulation results show that our proposed scheme outperforms the previous POXN architecture in terms of throughput and mean packet delay.

Game-Theoretic Queue-Stabilizing Backoff Algorithm in S-ALOHA and CSMA Systems

This letter investigates a queue-stabilizing backoff algorithm for slotted ALOHA and carrier-sense multiple access systems from game-theoretic perspective. Since queue stability of each user could be achieved when user’s throughput is greater than its mean packet arrival rate, every user tries to achieve its throughput up to a certain target level, by playing a non-cooperative game of determining a (re)transmission probability. We characterize Nash equilibrium points (NEPs) of this game and the convergence of a distributed backoff algorithm for users to employ to reach the NEPs.

An Analytical Black Hole Attack Model Using a Stochastic Topology Approximation Technique for Reactive Ad-Hoc Routing Protocols

This paper presents an analytical Black Hole attack model to predict the mean packet loss of ad-hoc networks using reactive routing protocols without apriori knowledge of the actual topology configuration. Topology information is summarized as a set of prototypical hop-distance profiles that describe likely hop distance perspectives within the topology and are generated using K-means clustering. Experiments are conducted to validate the theoretical attack condition, the hop-distance profiles, and prediction performance. Results show the model prediction falls within the 95% confidence intervals of packet loss through simulation of a variety of fixed and ad-hoc topologies.

Providing the full DDF link protection for bus-connected SIEPON based system architecture

Abstract Currently a massive amount of traffic per second is delivered through EPON systems, one of the prominent access network technologies for delivering the next generation network. Therefore, it is vital to keep the EPON optical distribution network (ODN) working by providing the necessity protection mechanism in the deployed devices; otherwise, when failures occur it will cause a great loss for both network operators and business customers. In this paper, we propose a bus-connected architecture to protect and recover distribution drop fiber (DDF) link faults or transceiver failures at ONU(s) in SIEPON system. The proposed architecture provides a cost-effective architecture, which delivers the high fault-tolerance in handling multiple DDF faults, while also providing flexibility in choosing the backup ONU assignments. Simulation results show that the proposed architecture provides the reliability and maintains quality of service (QoS) performance in terms of mean packet delay, system throughput, packet loss and EF jitter when DDF link failures occur.

Mitigating the IPTV Zap Time in Enhanced EPON Systems

Zap time (channel switching time) is a critical quality of experience (QoE) metric for IPTV systems where synchronization, signaling, and propagation delays are the components under consideration. An Ethernet passive optical network (EPON) is one of the main infrastructures in broadband access networks that provides high bandwidth with low propagation delay. The functionality of the EPON hardware architecture can be extended by adding programmable networking engine (PNE) and programmable sub-system (PSS) components in the optical line terminal (OLT) and optical network unit (ONU) as described in this paper to improve IPTV delivery performance for synchronization and signaling delays in terms of traffic localization. Furthermore, a new IPTV delivery mechanism is proposed to eliminate synchronization delay by buffering the current I-frames of broadcasted channels in the OLT for possible new coming requests and dropping additional streams along with the main stream. The OLTand ONUs implement a multicasting mechanism to handle part of the IPTV request as intra-domain traffic. Simulation results show that the proposed mechanism significantly improves the QoE and quality of service (QoS). IPTV bandwidth usage and system throughput have improved mean packet delays and packet loss in enhanced EPON architecture.

Decentralized SIEPON-Based ONU-Initiated Tx/TRx Energy-Efficiency Mechanism in EPON

An Ethernet passive optical network (EPON) has the least energy consumption among access network technologies and is the best candidate for improving energy consumption by time utilization. Current studies have proposed OLT-initiated schemes to turn off the transmitter/ receiver of an optical network unit (ONU) for a substantial time in order to achieve energy savings. In this paper, a new SIEPON-based ONU-initiated energy-saving mechanism is proposed in which the ONU calculates the transmitter (Tx) sleep duration based on the current queue state and maximum boundary delay requirements and forwards it to the OLT; then, the OLT calculates the ONU’s receiver (Rx) sleep duration and decides the ONU's sleeping mode in Tx or TRx sleep mode. Furthermore, the Sleep manager and Green DBA and TRx controller components are proposed in the OLT and ONU architectures to more precisely manage the energy-saving mechanism. Simulation results show that the proposed energy-saving mechanism significantly improves energy savings up to 47% and 42% in the up- and downstream directions, respectively, and guarantees the QoS requirement in terms of mean packet delay, packet loss, throughput, and jitter. Moreover, the proposed energysaving mechanism has better delay performance compared with the OLT-initiated energy-saving mechanism such as upstream centric scheduling.

A separate design principle for priority-aware packet collection in industrial cyber-physical systems

Industrial cyber-physical systems (ICPS) bridge the physical factory floor and the cyber computational space by leveraging the emerging techniques, such as wireless sensor networks for ubiquitous connection and perception, where sensors are deployed to monitor and collect industrial data according to different timeliness requirements. Priority-aware schemes are often used to tackle the differentiated data packet collection. However, it is challenging to coordinate the multichannel access while meeting the priority-aware transmission requirement in ICPS. In this paper, we propose a separate design principle (SDP) for priority-aware packet collection. In SDP, the transmission of each priority class of sensors is separately scheduled by a multichannel superframe which fully uses the available channels. As a result, each time slot on each channel is repeatedly scheduled to sensors of different priorities by different superframes. Then, a priority-aware transmission mechanism is devised to coordinate the transmissions of different sensors in the predefined priority order. Simulation results show that for four priorities, SDP achieves as low as 16, 18, 23, and 36 % of the mean packet transmission delay of non-overlap TDMA scheduling for each priority class, respectively. Moreover, SDP greatly outperforms IEEE 802.15.4e protocol for packet collection with two priorities. We also demonstrate the feasibility of SDP based on the implementation of software-defined radios.

Dynamic Buffer Status-Based Control for LTE-A Network With Underlay D2D Communication

This paper explores the problem of joint mode selection, spectrum management, power control, and interference mitigation for device-to-device (D2D) communication underlaying a Long Term Evolution-Advanced (LTE-A) network. We consider a dynamic mode selection scenario, in which the modes (D2D or cellular) of the devices depend on optimal allocations. To improve the quality of service (QoS) for the users, the optimization objective in a corresponding problem is formulated in terms of buffer size of user equipments (UEs), which is estimated based on buffer status information collected by the UEs. The realizations of a resource allocation approach presented in the paper include its real-time and non-real-time implementations, as well as two modifications applicable to a standard LTE-Direct (LTE-D) network. Performance of the proposed algorithms has been evaluated using the OPNET-based simulations. All algorithms show improved performance in terms of mean packet end-to-end delay when compared to most relevant schemes proposed earlier.

Performance analysis of passive optical networks with energy saving through the integrated sleep mode

Improving the energy efficiency has become an important aspect of designing optical access networks to minimize their carbon footprints. In this context, interleaved polling with adaptive cycle time (IPACT) with the integrated sleep mode is considered as a medium access control (MAC) scheme to improve the energy efficiency of passive optical networks (PONs). The decision criterion for energy saving is to put an ONU in the sleep mode when no upstream and downstream traffic exists, without impairing the desired quality of service (QoS) requirements in terms of the mean packet delays. We derive approximated and conservative closed form expressions of the upstream and downstream mean packet delays for the integrated sleep mode by modeling a PON as an N-user M/G/1 queue with reservations and vacations. Simulation experiments are conducted to validate the need of joint consideration of upstream and downstream traffic to avoid excessive delays in packet transmissions. Simulation experiments also validate the analytical results and show that the mean packet delays are relatively insensitive to packet arrival statistics for large sleep periods. Hence, our analytical results may also be applied to more practical scenarios with non-Poisson packet arrivals.