蓝牙分组传输性能分析与自适应分组选择策略

分析了蓝牙2．0＋EDR新规范定义的3种调制方式在AWGN信道下的位错误率与平均接收信噪比的关系，推导了ACL分组的重传概率与平均接收信噪比的函数表达式。通过分组的重传概率与特性分析了ACL分组的传输性能，包括平均吞吐量、平均重传次数、平均传输时延等。提出了AWGN信道下的自适应分组选择策略，通过在不同的信噪比情况下选择合适的分组类型进行传输而获得最大吞吐量，给出了进行分组类型切换的信噪比门限值。分析结果与提出的策略适用于蓝牙数据传输性能的优化。     

蓝牙L2CAP协议的功能及应用分析

本文针对蓝牙协议中的逻辑链路控制和适配层（L2CAP）的功能及其应用作了描述和讨论。     

一种自适应cdma2000无线链路层重传算法

TCP应用是3G无线网络中常用的分组数据业务,而无线网络较大的物理层帧差错率(FER)是影响网络性能的一个主要因素,链路层重传技术是改善网络性能因无线信道误码率大而下降的一项重要措施。主要研究cdma2000中链路层重传技术对无线TCP数据传输的影响。提出一种能改善TCP传输性能的自适应链路层重传算法。通过OPNET仿真工具对该重传算法进行仿真,验证了该算法在一定程度上能提高cdma2000无线网络中的TCP数据传输吞吐量。     

面向轨道交通的数据无线分组自适应选择策略

本文提出了一种基于SNR估计的蓝牙分组自适应选择策略.接收端采用M2M4估计方法对接收到的分组进行SNR估计,并根据SNR估计值所属区间来判定信道的最佳分组类型,通过返回PDU通知发送端需要选择的分组类型.该策略通过对信道进行SNR估计,很好的了解了信道的变化情况,保证了传输分组为最佳分组使系统的吞吐量达到最大.     

基于分组策略的RFID自适应防碰撞算法的研究

针对射频识别系统中的标签碰撞问题,提出了一种基于分组策略的RFID自适应防碰撞算法。该算法在二叉树搜索算法的基础上引入分组策略、后退策略、自适应地选择四叉树搜索策略和动态调整标签碰撞检测过程策略,减少了搜索次数和读写器与标签间的通信量,提高了识别效率。     

蓝牙协议一致性测试和蓝牙测试仪

该文介绍了蓝牙协议一致性测试技术,提出蓝牙协议一致性测试的三种典型测试解决方案,并简要介绍了IVT公司推出的第一台蓝牙测试仪。     

自适应判决门限延时相关分组检测算法

提出了结合双滑动窗口方法和延时相关分组检测的优化算法。该算法利用双滑动窗口算法在峰值点可以用于估计接收信号信噪比的特点,通过对接收信号信噪比的简单估计来确定最佳判决门限,动态跟踪信道变化,使分组同步更加准确。新算法在IEEE802.11a系统中进行了仿真,结果表明新算法的性能比原延时相关分组检测算法有了很大提高。     

蓝牙跳频算法的分析与改进

文章首先介绍了蓝牙跳频系统中跳频序列的产生算法,接着以此算法为基础,以躲避干扰为目的,从提高系统抗干扰能力的角度出发,提出了一种改进的自适应跳频方案来进一步改善系统的性能。     

OFDM系统中采用自适应天线阵列的下行分组调度算法研究和性能比较

基于OFDM下行系统,提出并比较了自适应天线阵列和分组调度算法结合的三种方式:(1)分组调度选择用户,自适应天线服务用户;(2)自适应天线参与选择用户,并且服务用户;(3)空分方式选择用户,自适应天线服务用户.仿真结果显示自适应天线阵列可以明显提高小区吞吐率等指标,并且(2)和(3)的性能优于(1).     

分组交换网络传输信道分类选择算法优化研究

为了提高分组交换网络的信道均衡性,改善通信质量,降低网络传输的误码率,提出一种基于判决反馈自适应筛选的分组交换网络传输信道分类选择算法。采用自适应加权控制对分组交换网络的信道相位信息进行星座图划分,采用横向时域滤波器方法进行信道中的干扰抑制,然后结合判决反馈自适应筛选方法实现网络传输信道的分类选择及均衡处理。最后进行实验分析,结果表明采用该算法进行分组交换网络传输信道分类选择时,信道的自适应均衡性能较好,网络数据传输的误码率较低。     

蓝牙网络上的IP传输

介绍了一种运行于蓝牙网络的IP机制,提出了解决IP分组如何在蓝牙协议上传输的方案,从而实现蓝牙的无线接入。     

基于Bluetooth的局域网接入规范

Bluetooth是一项全球统一的短距离无线通信标准，具有广阔的应用前景。首先介绍了其中的规范之一--LAP，然后就他与Bluetooth的其他规范和应用模型之间的关系进行论述，最后描述其协议和实体以及用户界面。     

An enhanced XOR‐based scheme for wireless packet retransmission problem

Solving wireless packet retransmission problem (WPRTP) using network coding (NC) is increasingly attracting research efforts. However, existing NC‐based schemes for WPRTP are with high computational complexity resulting from computation on larger Galois field (GF(2^q)), or the solutions on GF(2) found by the schemes are less efficient. In this paper, combining the basic ideas in two existing schemes, denoted as ColorNC and CliqueNC, respectively, we present a new scheme named as ColorCliqueNC. The advantages of ColorCliqueNC include the following: (i) it is suitable for all kinds of WPRTP instances; (ii) it works on GF(2); thus, it is computationally efficient than the schemes working on larger Galois fields; and (iii) the solutions found by ColorCliqueNC usually have fewer packet retransmissions than those by ColorNC and CliqueNC despite that they all work on GF(2). Theoretical analysis indicates that ColorCliqueNC is superior to ColorNC and CliqueNC. Simulation results show that ColorCliqueNC generally outperforms ColorNC and CliqueNC. Compared with ColorNC, ColorCliqueNC can save up to 10% packet retransmissions. Copyright © 2013 John Wiley & Sons, Ltd.     

家庭信息网络与“蓝牙”技术

论述家庭信息网络和一种新型的短距离无线连接技术“蓝牙”,探讨家庭信息网络的特点,比较几种无线连接技术的优缺点,在此基础上提出家庭信息网络拓扑结构,并详细介绍“蓝牙”技术独特的核心协议。最后描绘家庭信息网络和“蓝牙”技术的应用前景。     

Adaptive threshold control scheme for packet acquisition

An adaptive threshold control scheme for packet acquisition is described. The threshold control is done adaptively by setting the threshold proportional to the maximum likelihood estimate of the noise power     

Weight Pick: an efficient packet selection algorithm for network coding based multicast retransmission in mobile communication networks

This paper proposes an efficient packet selection algorithm, called Weight Pick, for improving the efficiency of a network coding based multicast retransmission protocol in mobile communication networks. Unlike existing packet selection algorithms, Weight Pick introduces the concept of a dynamic combination number in performing network coding. Based on this concept, a base station dynamically determines the number of packets combined or encoded in a retransmission packet based on the current packet receiving status of users and the combination number for each retransmission packet can be different. In packet selection, Weight Pick attempts to find an encoding combination whose weight is not less than (C ? 1) for every user, where C is the combination number of that retransmission packet. Simulation results show that Weight Pick can significantly improve the retransmission performance as compared with existing packet selection algorithms in terms of both packet loss ratio and packet transmission delay.     

Random network coding‐based optimal scheme for perfect wireless packet retransmission problems

Solving wireless packet retransmission problems (WPRTPs) using network coding (NC) approach is increasingly attracting research efforts. However, existing researches are almost all focused on solutions in Galois field GF(2), and consequently, the solutions found by these schemes are usually less optimal. In this paper, we focus on optimal NC‐based scheme for perfect WPRTPs (P‐WPRTPs) where, with respect to each receiver, a packet is either requested by or already known to it. The number of retransmitted packets in optimal NC‐based solutions to P‐WPRTPs is firstly analyzed and proved. Then, random network coding‐based optimal scheme (RNCOPT) is proposed for P‐WRPTPs. RNCOPT is optimal in the sense that it guarantees to obtain a valid solution with minimum number of packet retransmissions. Furthermore, in RNCOPT, each coding vector is generated using a publicly known pseudorandom function with a randomly selected seed. The seed, instead of the coding vector, is used as decoding information to be retransmitted together with the coded packet. Thus, packet overhead of RNCOPT is reduced further. Extensive simulations show that RNCOPT distinctively outperforms some previous typical schemes for P‐WPRTPs in saving the number of retransmitted packets. Copyright © 2011 John Wiley & Sons, Ltd.     

Adaptive wavelet packet basis selection for zerotree image coding

Image coding methods based on adaptive wavelet transforms and those employing zerotree quantization have been shown to be successful. We present a general zerotree structure for an arbitrary wavelet packet geometry in an image coding framework. A fast basis selection algorithm is developed; it uses a Markov chain based cost estimate of encoding the image using this structure. As a result, our adaptive wavelet zerotree image coder has a relatively low computational complexity, performs comparably to state-of-the-art image coders, and is capable of progressively encoding images.