Packet Rejection Probability Research Articles

Destination buffer analysis for packets rejection obliteration in multi-channel networks

In this paper we study a multi-channel network, each station of which is equipped with a network interface that has a receiver buffer of multiple packets. In this way, each station is able to receive multiple packets per time instant. We adopt a synchronous access protocol which is affected by the collisions over the multiple channels and the destination conflicts. The proposed protocol performance crucially depends on the size of the receiver buffer since it determines the packet rejection probability at destination. An analytical probabilistic model based on a Markovian process is adopted for the performance measures derivation by means of closed mathematical formulas. The proposed protocol is compared to relative ones that either totally ignore the receiver collisions or assume a receiver buffer of a single packet capacity. The numerical results show that the increase of the receiver buffer size improves the performance decisively, resulting in higher throughput and lower delay and rejection probability. Also, it is shown that the appropriate receiver buffer size per station in order for the rejections at destination to be effectively eliminated is not unlimited but is limited to three packets for 0.1% accepted maximum level of rejection probability.

The choice of optimal 3-rd order polynomial packet dropping function for NLRED in the presence of self-similar traffic

Abstract Algorithms of queue management in IP routers determine which packet should be deleted when necessary. The article investigates the influence of the self-similarity on the optimal packet rejection probability function in a special case of NLRED queues. This paper describes another approach to the non-linear packet dropping function. We propose to use the solutions based on the polynomials with degree equals to 3. The process of obtaining the optimal dropping packets function has been presented. Our researches were carried out using the Discrete Event Simulator OMNET++. The AQM model was early verified using the discrete-time Markov chain. The obtained results show that the traffic characteristic has the great impact on the network node behavior, but self-similarity of network traffic has no influence on the choosing of the optimal dropping packet function.

Self-stability of slotted ALOHA by limiting the number of retransmission trials in infrastructure-less wireless networks

In infrastructure-less wireless networks, mobile nodes may communicate with each other directly without a central entity (base station) using half-duplex slotted ALOHA protocol. The traffic arrival rate to each receiving mobile node from its neighboring transmitting nodes is independent of the mobile nodes' density. The network traffic can be controlled very precisely from each mobile node. The stability of the system can be achieved without the knowledge of current network condition and we defined it as self-stability and the system as self-stabilized system. In this paper, throughput, packet rejection probability and self-stability with and without retransmission cut-off are studied in terms of five parameters. These five parameters are the new packet transmission probability of each mobile node, probability that a mobile node is in an idle mode, the receiving probability of each mobile node, capture ratio and the number of retransmission trials. Limiting the number of retransmission trials is not needed, if the new packet transmission probability of each mobile node is below a certain limit. The value of this critical limit is derived analytically. The results of this study may be used for a self-stabilized system design of an infrastructure-less contention-based multiple access schemes with and without capture and retransmission cut-off.

A self-optimized random access protocol for an infrastructure-less mission critical wireless networking system

A random access protocol with multiple receivers per mobile node for infrastructure-less mission critical wireless networking system is introduced and analyzed. Each receiver of a mobile node may receive a packet in the presence of collision depending on the receiver quality defined as capture ratio. The maximum throughput per mobile node depends exclusively on the number of receivers per node and the capture ratio. Since the maximum throughput is independent of the variable factors of the network, the network is self-optimized. The self-optimized throughput increases with the increase of the number of receivers per node and the quality of each receiver (defined as capture ratio). On the other hand, the cost per mobile node also increases with the increase of the number of receivers per node and the quality of each receiver. The trade-off between the self-optimized throughput per node and the cost per mobile node is analyzed. In mission critical networking system, most of the traffic may be the real-time traffic, where the number of retransmission attempts is limited. The normalized delay is almost constant if the number of retransmission attempts is more than eight. However, the packet rejection probability decreases with the increase of the number of retransmission attempts.

An Optimized Iterative (Turbo) Receiver for OFDM Systems with Type-I Hybrid ARQ: Clipping and CFO Cases

An optimized iterative (Turbo) receiver for Orthogonal Frequency Division Multiplexing (OFDM) transmission is proposed for improved performance when used with type-I hybrid Automatic Repeat Request (ARQ) protocols. The proposed receiver is a Maximum Aposteriori Expectation-Maximization (MAP-EM) Turbo processor that exploits information from all available transmissions of a packet, including failed and new ones. Two distinct practical problems associated with OFDM are considered: (i) Clipping due to non-linearities in the transmit amplifier, and (ii) Carrier frequency offset (CFO). In the optimized scheme, failed transmissions are combined with the new ones to form an iterative receiver that jointly estimates the channel, compensates for the distortion (clipping, or CFO) and decodes the message. The modulation employed is M-ary Phase Shift Keying (MPSK). The system uses an embedded pilot structure for initial channel estimation of the channel, which is assumed doubly-selective. It is shown that gains on the order of 3 dB are achieved in the packet rejection probability with the proposed system. The performance of the optimized system is close to that of the ideal system, i.e. one that performs packet combining with perfect channel knowledge, no clipping, and no CFO.

Markovian receiver collision analysis of high-speed multi-channel networks

Two synchronous transmission multi-channel multi-access protocols for high-speed network architecture are studied in this paper. Analytic discrete time Markovian models are developed for finite number of stations and finite number of channels for the symmetric and asymmetric access rights proposed protocols. The effect of receiver collision phenomenon is examined and analysed on the performance measures evaluation and estimated by the probability of packet rejection at destination. Also, numerical results are presented for comparison for various numbers of data channels and stations. Copyright © 2005 John Wiley & Sons, Ltd.

An Optimum Retransmission Cut-Off Scheme for Slotted ALOHA

The retransmission cut-off is not needed for a stable operation of slotted ALOHA if the new packet generation rate is below a critical limit. The throughput never reaches its maximum value if the new packet generation rate is less than this critical limit irrespective of the number of transmissions. The maximum throughput is attained by adjusting the number of transmissions, pertaining to the new packet generation rate exceeding the critical limit. A complete analysis for the new packet generation rate with the proper adjustment of the number of transmissions that maximize the channel throughput in a Rayleigh fading channel is executed. A stable operating region in terms of the packet rejection probability and the corresponding number of transmissions is devised.

Buffered Type-II Hybrid ARQ Protocol for DS-SSMA Packet Radio Systems

The performance and stability of a slotteddirect-sequence spread-spectrum multiple-access (DSSSMA)packet radio network employing the type-II hybridautomatic-repeat-request (ARQ) protocol withfinite-length transmitter buffers are considered. Theequilibrium point analysis (EPA) technique is employedto analyze the system stability and to approximatelycompute the system throughput, delay, and packetrejection probability. It is found that the systemexhibits bistable behavior in some situations. Issues ofsystem design, such as the required length of thetransmitter buffers and the desirable region ofoperation based on a predetermined performancerequirement for packet rejection, are alsoinvestigated.

Frequency-hopped spread-spectrum random access with retransmission cutoff and code rate adjustment

A transmission policy for frequency-hopped spread-spectrum random-access communication systems in which the retransmission of a blocked packet at each station is determined as a function of that station's own collision experience is examined. For stability considerations and for channel throughput increase, the information packet is encoded by a Reed-Solomon code. An equilibrium analysis is used to show that undesirable bistable behaviour can be avoided if packets are rejected after a certain number of transmission attempts and the code rate is adjusted accordingly. The region of code rate and number of transmission attempt pairs that guarantees the network stability are investigated. The packet rejection probability, average packet delay, and maximum stable throughput are evaluated. >

Performance analysis of slotted rings with finite buffers

Many modelling studies have been conducted on a slotted ring with station buffers which are assumed to be either one or infinity. In reality, stations have finite buffers and arriving packets are rejected at a full buffer. This paper studies the behaviour of a slotted ring with finite buffering capability using a two-dimensional discrete time Markov chain. The characteristics of the single station and its interactions with the other stations in the ring are modelled and superposed on an N-station ring. From the model, it is relatively easy to compute the properties of the ring such as normalised throughput, mean packet access delay and packet rejection probability. The analytical model is validated via simulations. In addition, an infinite buffer model is constructed and compared with the finite buffer model. Using these two models, an optimum buffer length can be computed.

A simulation study of delay in multichannel CSMA/CD protocols

Simulation is used to estimate the performance of media access control (MAC) protocols derived from carrier-sense multiple access with collision detection (CSMA/CD), and operating in local area networks comprising several parallel broadcast channels. The influence of possible protocol and system alternatives on the network performance is discussed, based on results of the packet delay average, variance, mean square, coefficient of variation, and histogram, as well as the packet rejection probability due to lack of buffer space. The delay incurred by multipacket messages is estimated, comparing the single channel to the multichannel option. Numerical results indicate that the multichannel option provides reductions in both the packet delay average and variance, even when stations are only able to simultaneously receive from a subset of channels.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Theory Of Markovian Access to Collision Channels

In this paper, a unified, analytical framework for analysis of Markovian access control protocols in collision channels with a finite number of buffered users is presented. The theory developed is based on: 1) an appropriate state-space modeling of a network, 2) the averaging theory for the slow-in-the-average Markov walks used for the local analysis, and 3) an asymptotic large deviations theory used for the global analysis. Specific new results obtained here are: 1) formulas for the steady-state buffer OCCupancy and the probability of packet rejection, 2) a relationship between the capacity of the users buffers and the steady-state throughput, time delay, and the probability of packet rejection, 3) an asymptotic formula for the saturation period, and 4) a new adaptive protocol, the adaptive TDMA, is constructed, and it is shown that it is superior to the adaptive ALOHA system.

Queueing analysis of buffered slotted multiple access protocols

Much of the literature on the performance evaluation of multiple access protocols has assumed a buffer capacity of one unit. This assumption is not realistic. In practice the buffer capacities used are larger than one unit in order to reduce the probability of packet rejection. This is more crucial for multiple access protocols, which allow moderate to high values of the expected throughput (URN, Random TDMA etc.). In this paper, a model appropriate for the analysis of buffered slotted multiple access schemes is proposed. The method can be applied to several multiple access protocols such as the URN protocol, the ALOHA protocol, Random TDMA etc. The cases of infinite and finite buffer capacity are examined separately but under the same basic assumptions. The analysis is based on the assumption that each user process can be modelled as an M/G/1 queueing system. The proposed method requires a small amount of computation and is characterized by a high speed, a fact that simplifies the buffer's design as well. The solution obtained is extremely accurate and exhibits excellent agreement with simulation results, which corroborate the accuracy of the model. The special case when the buffer capacity is equal to 1 is examined. In that case, the present approach also allows for computation of the packet delay distribution.

On the Dynamic Control of the Urn Scheme for Multiple Access Broadcast Communication Systems

The Urn scheme is known to perform better than optimal ALOHA and TDMA for all ranges of traffic rates. In this paper we discuss the dynamic behavior of the Urn scheme to show that it possesses bistable behavior in a manner similar to ALOHA schemes and that dynamic control procedures can be applied to improve the system performance effectively. In particular, an input control procedure (ICP) is presented that gives a delay-throughput characteristic very close to optimal (perfect scheduling) for a wide range of throughput rates. The improvement is obtained at no extra cost in terms of information acquisition and the complexity introduced is minimal. An analytical method is described to calculate the expected delay, throughput, and the probability of packet rejection. Numerical results are shown for various values of user population and compared with corresponding results for other schemes.