Variable-length Packets Research Articles

ANALYSIS OF DEVELOPMENT TRENDS IN MODERN BUSINESS COMMUNICATIONS

Advanced communication techniques are used to organize fixed-user access to corporate communication network (CCNs) resources, with the ability to quickly change the encoding speed during network overloads. Estimating the probability of a denial of service caused by a lack of free channel resources at Access Network was one of the research's aims. IP based network enable the delivery of different services. Primary determinants of users' subjective quality evaluation of communication: data transmission: fast, without errors or failures; video communication: high-quality images, no delays; audio communication: no voice distortion, no call failures. Important to network operators to make effective use of their own resources while maintaining transmission quality standards. Control over metrics such packet loss ratio, delay variations, and latency is crucial. For certain corporate networks, the implementation of 5G mobile communication equipment holds great potential, especially in terms of enabling remote access for staff members. Simultaneously, concerns over unauthorized access to information and the risk of packet loss during transmission have become increasingly pressing. This paper discusses the effectiveness of Low-Density Parity Check (LDPC) codes and polar codes in variable length packet transmission in a 5G system. The modeling results of 5G communication system operation at a fixed value of packet loss are discussed.

Deficit Round-Robin: A Second Network Calculus Analysis

Deficit Round-Robin (DRR) is a widespread scheduling algorithm that provides fair queueing with variable-length packets. Bounds on worst-case delays for DRR were found by Boyer et al., who used a rigorous network calculus approach and characterized the service obtained by one flow of interest by means of a convex strict service curve. These bounds do not make any assumptions on the interfering traffic hence are pessimistic when the interfering traffic is constrained by some arrival curves. For such cases, two improvements were proposed. The former, by Soni et al., uses a correction term derived from a semi-rigorous heuristic; unfortunately, these bounds are incorrect, as we show by exhibiting a counter-example. The latter, by Bouillard, rigorously derive convex strict service curves for DRR that account for the arrival curve constraints of the interfering traffic. In this paper, we improve on these results in two ways. First, we derive a non-convex strict service curve for DRR that improves on Boyer et al. when there is no arrival constraint on the interfering traffic. Second, we provide an iterative method to improve any strict service curve (including Bouillard’s) when there are arrival constraints for the interfering traffic. As of today, our results provide the best-known worst-case delay bounds for DRR. They are obtained by using the method of the pseudo-inverse.

Performance analysis of asynchronous priority-based internet router under self-similar traffic input - queueing system with Markovian input and hyper-exponential services

In this paper, queueing behaviour of asynchronous priority-based internet router with self-similar traffic input is analysed. As Markov modulated Poisson process (MMPP) emulates self-similar traffic, it is used as input process of pertinent queueing system. For quality of service (QoS) guarantee in a broadband integrated services digital network (B-ISDN), partial buffer sharing (PBS) mechanism is promising one. Since, network traffic is asynchronous and of variable packet lengths, wavelength division multiplexing (WDM) technology is to be employed, according to which, each output port is modelled as multi server queueing system. The service times (packet lengths) are assumed to follow hyper-exponential (Hk) distribution. For the said reasons, router here is modelled as MMPP/Hk/s/C queueing system employing PBS mechanism. High and low priority packet loss probabilities, and mean lengths of non-critical and critical periods are computed, and presented graphically. This analysis is useful in dimensioning the priority-based asynchronous router with self-similar traffic input.

Performance analysis of asynchronous priority-based internet router under self-similar traffic input - queueing system with Markovian input and hyper-exponential services

In this paper, queueing behaviour of asynchronous priority-based internet router with self-similar traffic input is analysed. As Markov modulated Poisson process (MMPP) emulates self-similar traffic, it is used as input process of pertinent queueing system. For quality of service (QoS) guarantee in a broadband integrated services digital network (B-ISDN), partial buffer sharing (PBS) mechanism is promising one. Since, network traffic is asynchronous and of variable packet lengths, wavelength division multiplexing (WDM) technology is to be employed, according to which, each output port is modelled as multi server queueing system. The service times (packet lengths) are assumed to follow hyper-exponential (Hk) distribution. For the said reasons, router here is modelled as MMPP/Hk/s/C queueing system employing PBS mechanism. High and low priority packet loss probabilities, and mean lengths of non-critical and critical periods are computed, and presented graphically. This analysis is useful in dimensioning the priority-based asynchronous router with self-similar traffic input.

Enhanced Privacy Preservation in the Routing layer with Variable-length packet data for Attack Free IoT Sector

Enhanced Privacy Preservation in the Routing layer with Variable-length packet data for Attack Free IoT Sector

Wireless Feedback Control With Variable Packet Length for Industrial IoT

This letter considers a wireless networked control system (WNCS), where a controller sends packets carrying control information to an actuator through a wireless channel to control a physical process for industrial-control applications. In most of the existing work on WNCSs, the packet length for transmission is fixed. However, from the channel-encoding theory, if a message is encoded into a longer codeword, its reliability is improved at the expense of longer delay. Both delay and reliability have great impact on the control performance. Such a fundamental delay-reliability tradeoff has rarely been considered in WNCSs. In this letter, we propose a novel WNCS, where the controller adaptively changes the packet length for control based on the current status of the physical process. We formulate a decision-making problem and find the optimal variable-length packet-transmission policy for minimizing the long-term average cost of the WNCSs. We derive a necessary and sufficient condition on the existence of the optimal policy in terms of the transmission reliabilities with different packet lengths and the control system parameter.

Design of a 640-Gbps Two-Stage Switch Fabric for Satellite On-Board Switches

Due to the limitation of hardware resources and high reliability requirements for satellite-borne switching equipments and the demand for the increasing network bandwidth, a new type of two-stage satellite on-board switch fabric is presented in this paper. The fully connected structure is composed of eight input modules and eight output modules. And each module has four shared-buffer memories, which guarantee the premise of high-throughput. Compared with the traditional three-stage CLOS switch fabric, central modules are not used in this design. And compared with the complicated inter-stage scheduling algorithm, this paper uses an improved WRR algorithm which supports multi-priority variable-length packets scheduling. This design reduces the consumption of hardware resources and meets the design requirements of satellite-borne switches. In addition, we used the Xilinx FPGA to implement this $32\times32$ two-stage switch fabric, and used ModelSim 10.6d to simulate and analyze the entire design. The simulation results show that the peak throughput of this structure can reach 640 Gbps when the system clock frequency is 200 MHz.

Studying The Effect of Sampling Time and Network Load on Wireless Networked Control Systems.

Wireless networked control systems (WNCS) are considered one of the main attracting topics in the control, communication and computing domains. One of the main problems that face these systems is the various time delays which occur in the measurements. The control design process would be complicated if there is a time delay in the feedback loop. Moreover, this delay affects the system performance in terms of instability. The literature of WNCS shows that the available controllers can deal with a limited number of nodes. Beyond this limit, the system becomes unstable. In this paper, an optimized Particle Swarm Optimization (PSO)-based PID and FOPID controllers are proposed for WNCS to control the plant wirelessly. The proposed controllers aim at minimizing the time delays and can make the system remains stable when the network tackles a large number of nodes with variable length packet sizes. The performances of the proposed optimized controllers are compared to show which one of them can be more robust against the challenges of WNCS, namely varying time-delays, to handle a greater number of nodes. The results show that the FOPID is more powerful than the PID controller.

Impact of Variable Packet Length on the Performance of Heterogeneous Multimedia Wireless Sensor Networks

Performance valuation of wireless sensor network (WSN) routing protocols calls for realistic data traffic models because of their application specific nature. Since energy limitations is a cardinal issue for WSNs, network lifetime has become a key performance metric. In the quest towards energy efficiency, data packet length is an essential factor, especially in the multimedia applications. On one hand, a modest packet length brings down the packet loss, nonetheless, it results in dissipation of more energy. Thus, there comes forth a tradeoff in resolving the data packet length, where both low and high bit rates lead to certain energy inefficiency problems. This paper analyses the effect of variable packet length, being majorly ignored by routing protocols, on the network lifetime, throughput and reliability. The presented work is validated using computer simulations.

Optimization of Packet Length for MIMO systems

In this article, a method to enhance the throughput for Multiple Input Multiple Output (MIMO) systems by optimizing packet length is proposed. Two adaptation algorithms are proposed. In the first algorithm, we use the Average Signal to Noise Ratio (ASNR) to choose the optimal packet length and Modulation and Coding Scheme (MCS) in order to maximize the throughput. In the second algorithm, packet length and MCS are adapted with respect to the Instantaneous received SNR (ISNR). This article concludes that the variable packet length gives up to 1.8 dB gain with respect to the Fixed Packet Length (FPL).

Performances of two contention resolution units in optical SOA-MZI router

. We propose an optical router architecture with contention resolution unit. This router operates with asynchronous and variable length packets. FIFO technique is chosen for packet priority. The proposed router is implemented with SOA-MZI gates. The contention resolution unit is tested with two separate strategies, namely the deflection routing and the wavelength conversion. Error-free transmission up to 100 Gbps is guaranteed for both strategies with a penalty around 1 dB for wavelength conversion.

Analytical Study of Internet Routers Under Self-Similar Network Traffic with Voids

In this paper, Internet router employing priority based partial buffer sharing mechanism under self-similar variable length packet input traffic is investigated. Markovian arrival process (MAP) is employed to emulate self-similar traffic. Voids that occur in asynchronous networks are considered and are assumed to follow uniform distribution. Accordingly, average lengths of critical and non-critical periods against system parameters and traffic parameters studied by means of matrix geometric solutions and approximate Markovian models. This kind of study is useful in dimensioning the router under self-similar input traffic to provide differentiated services (DiffServ) and Quality of service (QoS) guarantee.

A Design for an Internet Router with a Digital Optical Data Plane

This paper presents a complete design for an optical Internet router based on the component steps required for Internet protocol (IP) packet forwarding. Implementations of hop count decrement and header matching are integrated with a simulation-based approach to variable-length packet traffic merging that avoids recirculation, demonstrating an approach for an all-optical data plane. A method for IPv4 checksum computation is introduced, and this and previously designed components are extended from binary to higher-density (multiple bits per symbol) encodings. The implications of this design are considered, including the potential for chip-level and system integration, as well as the requirements of basic optical processing components.

Loss behaviour analysis of asynchronous internet switch under self-similar traffic input using MMPP/PH/c/K queueing system employing PBS mechanism

In this paper, we analyse the loss behaviour of the wavelength division multiplexing (WDM) priority-based switch with self-similar traffic. As Markov modulated Poisson process (MMPP) emulates self-similar internet traffic one can use MMPP that is fitted for self-similar traffic as input process to investigate the queueing behaviour of the switch. In view of WDM technology in networking, each output port of switch is modelled as multi-server queueing system. In general, network traffic is asynchronous and of variable packet lengths. Service times (packet lengths) are assumed to follow more general one namely phase-type (PH) distribution. Partial buffer sharing (PBS) mechanism is employed to guarantee quality of service (QoS). Finally, switch under consideration is equivalent to MMPP/PH/c/K queueing system with PBS mechanism. The performance measures, high priority and low priority packet loss probabilities are computed. This type of analysis is useful in dimensioning the switch employing PBS mechanism under self-similar traffic input.

E-MAC: An evolutionary solution for collision avoidance in wireless ad hoc networks

Transmission collision is a main cause of throughput degradation and non-deterministic latency in wireless networks. Existing collision-avoidance mechanisms for distributed wireless networks are mostly based on the random backoff strategy, which cannot guarantee collision-free accesses. In this paper, we design a simple collision-avoidance MAC (E-MAC) for distributed wireless networks that can iteratively achieve collision-free access. In E-MAC, each transmitter will adjust its next transmission time according to which part of its packets suffering from the collision. And the iteration of this adjustment will quickly lead group of nodes converging to a collision-free network. E-MAC does not require any central coordination or global time synchronization. It is scalable to new entrants to the network and variable packet lengths. And it is also robust to system errors, such as inaccurate timing.

Performance Analysis of Wavelength Division Multiplexing Asynchronous Internet Router Employing Space Priority Mechanism under Self-Similar Traffic Input—Multi-Server Queueing System with Markovian Input and Erlang-k Services

In this paper, we analyze the queueing behaviour of wavelength division multiplexing (WDM) Internet router employing partial buffer sharing (PBS) mechanism with self-similar traffic input. In view of WDM technology in networking, each output port of the router is modelled as multi-server queueing system. To guarantee the quality of service (QoS) in Broadband integrated services digital network (B-ISDN), PBS mechanism is a promising one. As Markov modulated Poisson process (MMPP) emulates self-similar Internet traffic, we can use MMPP as input process of queueing system to investigate queueing behaviour of the router. In general, as network traffic is asynchronous (unslotted) and of variable packet lengths, service times (packet lengths) are assumed to follow Erlang-k distribution. Since, the said distribution is relatively general compared to deterministic and exponential. Hence, specific output port of the router is modelled as MMPP/Ek/s/C queueing system. The long-term performance measures namely high priority and low priority packet loss probabilities and the short-term performance measures namely mean lengths of critical and non-critical periods against the system parameters and traffic parameters are computed by means of matrix-geometric methods and approximate Markovian model. This kind of analysis is useful in dimensioning the router under self-similar traffic input employing PBS mechanism to provide differentiated services (DiffServ) and QoS guarantee.

Channel-Adaptive Packetization Policy for Minimal Latency and Maximal Energy Efficiency

This article considers the problem of delay optimal bundling of the input symbols into transmit packets in the entry point of a wireless sensor network such that the link delay is minimized under an arbitrary arrival rate and a given channel error rate. The proposed policy exploits the variable packet length feature of contemporary communications protocols in order to minimize the link delay via packet length regularization. This is performed through concrete characterization of the end-to-end link delay for zero error tolerance system with First Come First Serve (FCFS)queuing discipline and Automatic Repeat Request (ARQ) retransmission mechanism. The derivations are provided for an uncoded system as well as a coded system with a given bit error rate. The proposed packetization policy provides an optimal packetization interval that minimizes the end-to-end delay for a given channel with certain bit error probability. This algorithm can also be used for near-optimal bundling of input symbols for dynamic channel conditions provided that the channel condition varies slowly over time with respect to symbol arrival rate. This algorithm complements the current network-based delay-optimal routing and scheduling algorithms in order to further reduce the end-to-end delivery time. Moreover, the proposed method is employed to solve the problem of energy efficiency maximization under an average delay constraint by recasting it as a convex optimization problem.

Dynamic Antenna Management for Uplink Energy Efficiency on 802.11n Mobile Devices

An increasing number of mobile devices are being equipped with 802.11n interfaces to support bandwidth-intensive applications; however, the improved bandwidth increases power consumption. To address the issue, researchers are focusing on antenna management. In this paper, we present a dynamic antenna management (DAM) scheme to improve the uplink energy efficiency on mobile devices whose packet workloads may vary significantly and frequently. First, we model antenna management as an optimization problem, with the objective of minimizing the energy required to transmit a sequence of variable-length packets with random arrival times. Then, we propose an optimal offline algorithm to solve the problem, as well as a competitive online algorithm that has a provable performance guarantee and allows compatible implementations on 802.11n mobile devices. To evaluate our scheme, we conducted extensive simulations based on real mobile user traces and application transmission patterns. Nearly all commercial 802.11n mobile devices support the power save mode (PSM). Our results demonstrate that DAM can improve the energy efficiency of PSM significantly at a cost of slight throughput degradation.

End-to-End Delay Bounds for Variable Length Packet Transmissions under Flow Transformations

A fundamental contribution of network calculus is the convolution-form representation of networks which enables tight end-to-end delay bounds. Recently, this has been extended to the case where the data flow is subject to transformations on its way to the destination. Yet, the extension, based on so-called scaling elements, only applies to a setting of identically sized data units, e.g., bits. In practice, of course, one often has to deal with variable-length packets. Therefore, in this paper, we address this case and propose two novel methods to derive delay bounds for variable-length packets subject to flow transformations. One is a relatively direct extension of existing work and the other one represents a more detailed treatment of packetization effects. In a numerical evaluation, we show the clear superiority of the latter one and also validate the bounds by simulation results.

Performance analysis of buffers with train arrivals and correlated output interruptions

In this paper, we study a discrete-time buffer system with a time-correlated packet arrival process and one unreliable output line. In particular, packets arrive to the buffer in the form of variable-length packet trains at a fixed rate of exactly one packet per slot. The packet trains are assumed to have a geometric length, such that each packet has a fixed probability of being the last of its corresponding train. The output line is governed by a Markovian process, such that the probability that the line is available during a slot depends on the state of the underlying $J$-state Markov process during that slot. &nbsp First, we provide a general analysis of the state of the buffer system based on a matrix generating functions approach. This also leads to an expression for the mean buffer content. Additionally, we take a closer look at the distributions of the packet delay and the train delay. In order to make matters more concrete, we next present a detailed and explicit analysis of the buffer system in case the output line is governed by a $2$-state Markov process. Some numerical examples help to visualise the influence of the various model parameters.