一种改进的Ad hoc网络中动态TDMA时隙分配方法

无线自组织网络(Ad hoc)是一种不依赖基础设施的网络,网络中的节点均是有移动主机构成.文中提出了一种改进的TDMA时隙分配方法,根据网络拓扑结构及带宽需求,本方法可以动态的改变帧长和发送机制,而且允许发送者预约邻居节点中未分配的时隙,仿真结果表明此协议优于USAP及802.11协议.     

一种改进的动态TDMA时隙分配算法研究

针对移动自组织网络(Mobile Ad-Hoc Networks,MANET)对多节点场景的需求,在基于时分多址(Time Division Multiple Access,TDMA)固定时隙分配的基础上提出了一种改进的动态TDMA时隙分配算法。该算法根据节点数目的改变,通过针对不同的节点等级动态调整时隙分配策略,提高传输效率。对2种算法进行了对比仿真,仿真结果表明,改进的动态TDMA时隙分配算法更能适应节点数目不断变化的场景。     

一种TD-SCDMA系统的动态信道分配策略

提出了一种适用于TD-SCDMA系统的动态信道分配算法.该算法在进行资源整合的基础上将信道条件较好的用户分配于交叉时隙,从而达到减少交叉时隙干扰,提高频谱效率的目的.仿真结果表明该算法能够有效增加系统容量,改善系统性能.     

一种基于多天线的动态TDMA协议仿真研究

提出一种用于Ad Hoc网络MAC层的多天线、多信道动态TDMA协议,它采用一个全向天线和多个方向性的扇区天线.该协议通过空分复用控制,可提高网络的吞吐量,通过基于动态时隙分配算法和相应的邻居发现策略,以减少时隙空闲,提高信道利用率.利用NS-2平台进行的仿真研究表明,与单一全向天线的MAC协议相比,所提出的协议在吞吐量和时延方面有明显的提高.     

一种TD-SCDMA动态信道分配的改进方案

在TD-SCDMA系统中,由于对上下行不对称业务的需求,使得不同小区间的上下行切换点不同,因此会产生严重的小区间干扰(基站和基站间干扰)。提出一种基于移动台位置的抗基站间干扰的动态信道分配(DCA)的改进方案,它通过增大交叉时隙的空间隔离度和减少交叉时隙的使用机率来改善基站间的相互干扰,同时使每个时隙的用户空间分布更加均匀,最大化提高系统容量,改善非对称业务下系统的整体性能。     

在Ad Hoc 网络中的动态TDMA时隙分配

无线自组织网络（Ad Hoc）是一种不依赖基础设施的网络,网络中节点均是由移动主机构成。文中提出了一个建立在TDMA基础上的Ad Hoc时隙分配协议,它可以提高传输信道的效率,通过动态控制帧长为新加入者提供额外的非分配时隙。相比于传统的时隙分配协议该协议更近一步的促进了信道的实时利用率。     

一种适用于多信道联合组网的时隙分配新算法

分析了多信道联合组网时隙分配问题的特点,提出分配时隙时应该综合考虑容量需求、负载均衡和分配均匀度三方面因素,并设计了估计该三方面需求满足程度的方法。基于遗传算法,提出了适用于求解该问题的优化算法。仿真试验表明,提出的新算法能够有效求解多信道联合组网环境下的时隙分配问题。     

车载自组网中一种分布式自适应TDMA时隙分配策略

提出了一种适用于车载自组网的自适应TDMA时隙分配机制DATS,DATS利用节点的差异性优化TDMA时隙分配机制,并且能根据节点密度自适应地调节时隙分配比例。理论分析和实验结果表明,DATS时隙分配策略能提高节点竞争成功率,降低接入时延;与现有的几种协议相比能减少至少50%的节点冲突,且具有良好的可扩展性,能够适应局部节点密度的变化。     

基于动态优先级表的TDMA时隙分配

Ad Hoc网络组网效率提升的一个重要方面就是研究高效的时隙分配算法,动态TDMA时隙分配机制已经成为提高组网效率的一个热门研究点。这里基于动态优先级表提出一种新颖的动态时隙分配算法,该算法能在时间维上保证各节点对空闲时隙资源竞争使用的公平性。仿真结果表明基于动态优先级表的时隙分配算法能高效利用时隙资源,提高信道利用率。     

A Multichannel TDMA MAC Protocol to Reduce End‐to‐End Delay in Wireless Mesh Networks

Supporting QoS over multihop wireless mesh networks is difficult because end‐to‐end delay increases quickly with the increasing number of hops. This paper introduces a novel multichannel time‐division multiple‐access media access control (McTMAC) protocol that can help to efficiently reduce delay over multihop networks. Performance evaluation results demonstrate that McTMAC outperforms existing alternative protocols. The max‐delay can be reduced by as much as 60% by using McTMAC.     

EASA：一种分簇Ad Hoc网络高效自适应TDMA时隙分配算法

 提出一种适合于分簇Ad Hoc网络的高效自适应TDMA时隙分配算法EASA. EASA采用动态调整帧长以及根据簇内节点MAC层缓存队列长度进行自适应的时隙分配,解决了传统TDMA时隙分配算法中低传输速率节点占用不必要时隙的问题. 多个场景的实验结果表明,与传统TDMA时隙分配算法以及802.11相比,EASA可以大大提高网络吞吐量,很好的提高网络整体性能.     

A Network-Based Dynamic Channel Assignment Scheme for TDMA Cellular Systems

Network-based dynamic channel assignment (DCA) schemes can be used to increase the capacity of TDMA cellular systems. In this paper, a new distributed network-based DCA scheme, known as DCA with interference information, DCA-WI, is proposed and its performance is studied. In this scheme, a base station (BS) assigns a channel in such a way as to minimize the effect on the availability of channels for use in its interfering cells. To accomplish this, each BS maintains an interference information table which contains information about the local cell and its interfering cells. DCA-WI does not require system-wide information. Channel reassignment for new and completed calls are used to further reduce the call blocking probability. Simulation results show that DCA-WI provides a lower call blocking probability compared to other existing schemes in both uniform and nonuniform traffic distributions.     

TDMA卫星通信系统中一种话音业务统计复用算法

本文提出了一种用于计算统计复用ＴＤＭＡ卫星通信系统中话音业务应申请时隙数的算法，给出了计算公式，并进行了分析、计算和模拟。结果证明，采用这种时隙计算算法可在用户能接受的信元丢失概率下，达到比传统ＴＤＭＡ／ＤＡ方案高许多的时隙利用率，同时具有差不多的时延性能。     

Time slot assignment in a heterogeneous environment of a SS/TDMA system

In this paper we consider the time slot assignment for a heterogeneous environment in which circuit-switched traffic and packet-switched traffic share the same satellite. In constructing a single time division multiple access (TDMA) frame for both traffic types, their different characteristics must be taken into account. This problem is known to be NP-complete and a couple of heuristic partial optimization algorithms have been developed. In this paper, we first provide a theoretical result to improve the existing partial optimization algorithms; then a fully optimizing heuristic algorithm is presented. Simulation results show that our algorithm provides a much better solution quality than existing ones. © 1997 John Wiley & Sons, Ltd.     

A pilot-based dynamic channel assignment scheme for wireless access TDMA/FDMA systems

We propose a control architecture for implementing a dynamic channel assignment (DCA) algorithm which optimizes two-way channel quality in a TDMA portable radio system. Computer simulations are used to evaluate the performance of this DCA method. A common control frequency, which is frame-synchronized among base stations, provides (1) beacons for portables to locate base stations and obtain DCA information, (2) broadcast channels for system and alerting information, and (3) pilot signals to permit portables to evaluate downlink interference. This allows low-complexity radio ports and portables to mutually select channels to avoid interference and avoid creating excessive interference. Results from computer simulations demonstrate the good spectrum efficiency of this method and its potential for handling nonuniform traffic demand. This work is targeted toward understanding the implications to local exchange networks of wireless system alternatives that could provide access to those networks.A preliminary work with the same title was presented at the Second International Conference on Universal Personal Communications, October 12–15, 1993, Ottawa, Canada.     

一种短波数据链的动态TDMA协议

针对短波资源有限、传输速率低的特点,提出了基于短波数据链的动态TDMA协议（HF-DTDMA）,该协议能对短波信道资源进行自适应动态分配,提高信道利用率,满足短波网络业务量实时变化的需求。通过建立短波数据链的仿真场景,分析了动态TDMA协议的性能,并且与固定TD-MA机制的性能进行了对比分析,动态TDMA协议在吞吐量和传输时延上性能明显提升。仿真结果也表明,提出的动态TDMA协议在时效性和吞吐率上能满足短波数据链的设计要求。     

VANET中基于协议序列及TDMA的混合信道接入机制

为了提高高速公路场景下用户平均有效数据吞吐量,提出车载自组织网络分布式信道接入机制.通过道路区段划分实现协议序列集复用;通过引入少量反馈并利用UI(User Irrepressibility)序列特性实现节点间接入顺序感知;同区段节点间利用分布式TDMA(Time Division Multiple Access)模式最大化吞吐量.仿真结果表明,其吞吐量性能优于经典的基于GNSS(Global Navigation Satellite Systems)的机制,并且物理层数据传输速率越大,节点通信半径越大,车辆密度越稀疏,其优势越明显.     

Channel Borrowing Without Locking for Asynchronous Hybrid FDMA/TDMA Cellular Communications

The use of real time channel borrowing in digital cellular asynchronous hybrid FDMA/TDMA systems is considered. These systems, which are exemplified by North American digital cellular (IS-54), are asynchronous in the sense that time slots in different cells are not aligned. CBWL (channel borrowing without locking) techniques can be applied but (without cell-to-cell synchronization) borrowing individual time slots from adjacent cells would violate co-channel interference constraints. Instead, frequency carriers can be borrowed. In IS-54, a carrier supports three TDMA slots. So if only one TDMA slot is needed in the borrowing cell, two TDMA slots are unnecessarily transferred. We devised an appropriate carrier borrowing scheme and an analytical model to determine the traffic performance of TDMA/CBWL. Fast carrier returning is used to increase channel utilization by returning borrowed carriers as soon as possible. An efficient computational method that uses macro-states, decomposition, combinatorial analysis and the convolution algorithm is devised to find blocking probabilities. The results show that in comparison with FCA, the new CBWL scheme can significantly improve system performance of asynchronous TDMA cellular systems that use FDMA/TDMA multiplexing.     

一种基于动态TDMA时隙分配的攻击方法研究与实现

基于时分多址（Time Division Multipie Access）的MAC层协议在应用于AdHoc网络时，具有较好的稳定性，但同时也存在一些安全漏洞。文中在已有研究的基础上，进一步分析了TDMA帧结构，提出一种针对TDMA时间帧的攻击方法，并在NS2仿真平台上实现。通过前后网络性能的分析比较，可以看出该攻击效果明显，论证了攻击方法的可行性。论文的最后，我们针对该攻击，对相应的防御机制进行了分析和探讨。