Group improved enhanced dynamic frame slotted ALOHA anti-collision algorithm

With the development of information technology and declining in the cost of tags, radio frequency identification (RFID) system has become more and more popular, which has been widely used in a lot of areas, such as logistics tracking, animals identification, medicine, electronic toll collection, inventory, asset management, manufacturing, etc. However, when we use RFID technology to identify the objects, tag collision is one of the important factors to influence the identification efficiency. Currently, Aloha-based algorithm is one of the popular anti-collision algorithms which performs well when the number of tags is small. But it is not very efficient for cases with large number of tags and some areas which tags’ number can be estimated, such as warehouse, supermarket, the production lines of smart factory and so on. So in this paper, we proposed a new anti-collision algorithm called group improved enhanced dynamic frame slotted ALOHA (GroupIEDFSA) by estimating the number of unread tags first, comparing the maximum frame size and dividing tags into groups when the number of tags which are activated is large. What is more, compared with enhanced dynamic frame slotted ALOHA (EDFSA) algorithm in the process of identification, GroupIEDFSA algorithm will combine new group based on the unread tags’ number. Simulation results show that the efficiency of GroupIEDFSA algorithm system improves by 20 % in time and over 50 % in rounds than EDFSA algorithm in the standard mode, and increases by 1 % in time when we used fast mode.     

一种改进的RFID动态帧时隙ALOHA算法

射频识别(RFID)系统中,存在多个电子标签同时响应读写器的可能性,这将使得电子标签产生碰撞现象。在对帧时隙ALOHA算法分析的基础上,提出了一种改进的RFID动态帧时隙ALOHA算法。该算法通过对读写器范围内的标签数进行估计,设置最佳帧长度,使RFID系统获得最大吞吐量,从而提高标签的识别效率。仿真结果表明:与传统ALOHA算法相比,性能有明显改善。     

基于汉明重分组的动态帧时隙ALOHA 防碰撞算法

针对射频识别(RFID)系统中标签较多时动态帧时隙 ALOHA 算法识别效率快速下降的问题,在动态帧时隙 ALOHA 算法的基础上,利用标签 ID 前 M位的汉明重量对阅读器范围内标签进行分组,提出了一种基于汉明重分组的动态帧时隙 ALOHA 算法(LGDFSA),并利用 MATLAB 对它进行了仿真模拟。仿真结果表明,LGDF-SA 算法与动态帧时隙 ALOHA 算法相比,当标签数较多时,系统吞吐量提高,并趋于稳定,总操作数有所减少,系统总体效率提高。     

Enhanced frameless slotted ALOHA protocol with Markov chains analysis

In this paper, we propose a novel approach to enhance the performance of frameless slotted ALOHA (SA) protocol. We employ signature codes to help the receiver identify the packets contained in collisions, and use successive interference cancellation (SIC) for packet recovery. We model the proposed scheme as a two-state Markov model represented by a uni-partite graph. We evaluate the throughput, expected delay and average memory size of the proposed scheme, and optimize the proposed scheme to maximize the throughput. We show that the theoretical analysis matches well with simulation results. The throughput and expected delay of the proposed protocol outperform the conventional slotted ALOHA protocol significantly.     

Irregular repetition slotted ALOHA with total transmit power limitation

Dear editor, The slotted ALOHA(SA)[1]protocol has been widely used in the multiple access networks,wherein the frame is di-vided into equal-length slots and all...     

An adaptive buffer control scheme for slotted ALOHA satellite channels

The behaviour of the slotted-ALOHA random access satellite channel wherein each user with a finite buffer changes the retransmission probability in accordance with the queue length is studied. The finite buffer of each user is divided into a number of strata and whenever the queue length moves from one stratum to the other, the retransmission probability is changed to reduce the average queueing delay. The analysis carried out in this paper reveals that significant reduction in the delay can be achieved by this technique employing only a few strata.     

Throughput analysis of slotted ALOHA with cooperative transmission using successive interference cancellation

With a cross-layer design approach, a novel random access protocol is proposed in this paper, which is based on conventional slotted ALOHA (S-ALOHA) using successive interference cancellation (SIC) technique to separate collided packets and cooperative transmission to exploit the physical layer advantages. And a general theoretic analysis model is presented to obtain its throughput, which is also suitable for analyzing the performance of other protocols (such as S-ALOHA and S-ALOHA with cooperative transmission (C-ALOHA)) and is shown to be right and effective. Numerical results demonstrate that the proposed protocol can improve the maximal throughput by 190% and 132% over a Rayleigh fading channel, respectively, as compared with S-ALOHA and C-ALOHA. And the results show that our protocol can provide an effective random access method with high throughput for wireless transmission.     

自适应动态时隙ALOHA防碰撞算法的研究

时隙ALOHA算法是射频识别系统中通过分时复用方式的一种防碰撞算法,应答器在分配到的时隙中与阅读器进行数据交互.提出一种改进的自适应帧时隙ALOHA防碰撞算法,能够使得时隙到优化分配,进一步提高应答器的识别效率.     

Power level selection schemes to improve throughput and stability of slotted ALOHA under heavy load

We propose and analyse three different power selection schemes for slotted ALOHA random access protocol operating under multiple power levels. Through analysis and numerical examples we demonstrate that these schemes can significantly improve the performance of slotted ALOHA, in terms of throughput and stability, under heavy load. The proposed schemes are truly distributive in nature and can be easily implemented in wireless access systems without requiring any centralised control.     

基于排队理论的时隙ALOHA防碰撞算法

针对射频识别技术中存在的标签冲突问题,在时隙ALOHA算法的基础上,提出了一种改进算法.该算法利用排队理论,每次都让排在队首的标签进入空闲时隙,改善了时隙ALOHA射频防碰撞算法的时隙拥堵,这样就能减少时隙中标签的碰撞,并且还进一步对标签的应答建立了数学模型.通过理论分析以及在MATLAB软件上的仿真结果表明,该方法的识别率较高,同时降低了时隙内的碰撞概率.     

基于标签分组的动态帧时隙ALOHA算法

为解决无线射频识别技术系统中的多标签碰撞问题,提出一种基于标签分组的动态帧时隙ALOHA算法.将标签以ID信息分组为256个组后,阅读器按照标签ID号连续抽取8组,从该8组里每组挑取一个标签进行查询识别,标签收到命令后发送识别请求,阅读器记录碰撞时隙和空闲时隙数量情况并返回数值,标签以此调整时隙进行信息发送,标签按照确...     

一种基于ALOHA的改进RFID防碰撞算法

标签碰撞是无线射频识别(RFID)技术中的常见问题,它使得系统效率降低。ALOHA算法是解决此类问题的重要方法,提出了一种基于ALOHA的改进防碰撞算法,并分别给出了应用该方法处理碰撞时,阅读器和标签各自需要执行的程序步骤。仿真结果表明,该算法具有较高的效率,尤其在标签数量较大时相比动态帧时隙算法(DFSA)消耗时隙更少。     

Comments on "Analysis, stability, and optimization of slotted ALOHA with a finite number of buffered users"

The model of a buffered slotted ALOHA scheme presented by Saadawi and Ephremides in the above paper is improved by refining the USER and SYSTEM Markov chains. New expressions are proposed for the transition probabilities in the USER chain. The SYSTEM chain is also modified to account for the influence of an arriving packet on all possible transitions. The principle of flow balance at equilibrium (the net packet input flow rate should be equal to the rate of successful packet transmissions) is employed to justify these changes. Incorporating the proposed modifications, the packet flow equivalence condition is established analytically for the two-user, single-buffer case and numerically for systems with a larger number of users, each one having a single, finite, or an infinite buffer.     

改进ALOHA算法在RFID多目标识别中的应用

RFID系统中,由于多标签引起的冲突一直是影响系统性能的大问题。ALOHA算法是运用比较普遍的一种防冲突算法,在标签数目较少的情况下,现有的ALOHA算法也有较高的效率,但是随着标签数目的急剧增加,算法时间也成指数往上增长,本文提出一种改进的ALOHA算法,在标签总数未知的情况下,动态估计标签数目,以选择合适的窗口大小,获得较高的系统效率。仿真结果表明,跟传统ALOHA算法相比,性能有明显改善。     

A multiaccess tree algorithm with free access, interference cancellation and single signal memory requirements

Tree algorithms are a well studied class of collision resolution algorithms for solving multiple access control problems. Successive interference cancellation, which allows one to recover additional information from otherwise lost collision signals, has recently been combined with tree algorithms with blocked access [Y. Yu, G.B. Giannakis, SICTA: A 0.693 contention tree algorithm using successive interference cancellation, in: INFOCOM 2005. 24th Annual Joint Conference of the IEEE Computer and Communications Societies, Miami, USA, 2005, pp. 1908–1916], providing a substantially higher maximum stable throughput (MST): 0.693 for Poisson arrivals, given an infinite number of memory locations for storing signals. We propose a novel tree algorithm for a similar problem, but with two relaxed model assumptions: free access is supported and a single signal memory location suffices. A study of the maximal stable throughput of this algorithm is provided using matrix analytical methods; as a result, an MST of 0.5698 for Poisson arrivals is achieved. Our methodology also allows us to investigate the MST when the multiple access channel is subject to Markovian arrival processes.     

Analysis of a multiaccess control scheme

We consider a multiaccess channel under the infinite source model and ternary feedback. We consider a recently proposed scheme for the decentralized control of transmissions through the channel, and we prove that it is stable, as long as the rate of generation of new packets is smaller than e^-1.     

Performance analysis of a novel traffic scheduling algorithm in slotted optical networks

This paper considers the scheduling problem in a new slotted optical network called Time-Domain Wavelength Interleaved network (TWIN). The TWIN architecture possesses interesting properties, which may offer solutions for next-generation optical networks. Besides, better Quality of Service (QoS) could be achieved in TWIN by minimizing two parameters: queueing delay and delay variance. However, to the best of our knowledge, most of the existing scheduling algorithms in TWIN ignored consideration of QoS and focused mainly on maximizing the throughput. In this paper, we formulate the scheduling problem into an Integer Linear Programming (ILP) problem and propose a novel heuristic – Destination Slot Set (DSS) algorithm to solve it fast and efficiently. Besides, we derive an analytical model for TWIN and investigate the performance of DSS in it. By means of simulations, we demonstrate that our analytical model approximates the TWIN network very well; moreover, DSS incurs smaller queueing delay and delay variance, which ensures better QoS.     

On the instability of large-scale systems

A set of sufficient conditions for the instability of large-scale systems is presented. These conditions are much less restrictive than similar conditions derived in [1].