VTC Spring 2009 - IEEE 69th Vehicular Technology Conference最新文献_第7页

Traffic Measurement and Analysis of a Broadband Wireless Internet Access 宽带无线互联网接入的流量测量与分析

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073890

R. Pries, Florian Wamser, D. Staehle, K. Heck, P. Tran-Gia

引用次数: 29

Quantifying Performance Requirements of Vehicle-to-Vehicle Communication Protocols for Rear-End Collision Avoidance 车对车通信协议对追尾避碰性能的量化要求

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073822

M. Nekovee

引用次数: 51

Non-Colliding First Messages in Slotted ALOHA: Further Insights Toward a Practical Solution 开槽ALOHA中的非碰撞第一信息:对实用解决方案的进一步见解

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073714

Günther Brandner, Udo Schilcher, M. Gyarmati, C. Bettstetter

{"title":"Non-Colliding First Messages in Slotted ALOHA: Further Insights Toward a Practical Solution","authors":"Günther Brandner, Udo Schilcher, M. Gyarmati, C. Bettstetter","doi":"10.1109/VETECS.2009.5073714","DOIUrl":"https://doi.org/10.1109/VETECS.2009.5073714","url":null,"abstract":"Consider n nodes competing for access on a channel using slotted ALOHA. Our aim is to maximize the probability Φ that the first message within s slots does not collide. We derive an expression for the transmit probabilities in each slot, maximizing Φ. As opposed to previous work, the expression is non-recursive, thus easier to calculate and more convenient for practical implementations. Furthermore, we address the problem that, in practical applications, the number of competing nodes n is likely to be unknown and has to be estimated by each node. We study the sensitivity of channel access scheme with respect to deviations from the actual n via simulations. It is shown that overestimation of n is a better strategy than underestimation. • First, the computation of the optimum transmit proba- bilities requires each node to know the number n of nodes participating in the channel access competition on the shared medium. If this number is unknown, a node has to estimate it. An open research issue is thus to determine the impact on the performance due to errors in this estimation. The paper at hand investigates this issue, analyzing the sensitivity of the non-colliding first message probability as a function of the relative estimation error. It is shown that significant estimation errors lead to only small performance degradations, and that in general an overestimation of n is better than an underestimation. • Second, the calculation of the optimal slot access strategy is based on a recursive equation that depends on n in each recursion. This means the following: if the number of nodes changes, all s recursions must be recalculated. The paper at hand derives an alternative expression for the optimal transmit probabilities that enables us to store them in a table, where the values are independent from the number of nodes n.","PeriodicalId":253546,"journal":{"name":"VTC Spring 2009 - IEEE 69th Vehicular Technology Conference","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131402787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

An Asymptotically Fair Subcarrier Allocation Algorithm in OFDM Systems OFDM系统中渐近公平子载波分配算法

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073378

H. Rasouli, A. Anpalagan

{"title":"An Asymptotically Fair Subcarrier Allocation Algorithm in OFDM Systems","authors":"H. Rasouli, A. Anpalagan","doi":"10.1109/VETECS.2009.5073378","DOIUrl":"https://doi.org/10.1109/VETECS.2009.5073378","url":null,"abstract":"Dynamic subcarrier allocation improves the performance of OFDM systems by exploiting multi-user diversity. Fairness index is a parameter which indicates how fairly the sub-carriers are allocated among the users in a system. A greedy sub-carrier allocation algorithm optimizes the system performance in terms of throughput, but it sacrifices the instantaneous fairness. In this paper, we define a new term called \"asymptotic fairness\". It is shown that for a small number of users greedy subcarrier allocation algorithm leads to a normalized fairness index close to unity after a few channel realizations; therefore, if the users of the same group can wait for a few OFDM symbols, they all can get almost the same data rate. To generalize the idea for larger number of users, we have proposed grouping of the users into smaller group sizes. The proposed subcarrier allocation algorithm allocates the subcarriers in two steps: group-allocation and user-allocation. Group-allocation is performed to maintain fairness among different groups by using a fairness-oriented subcarrier allocation algorithm such as max-min algorithm. In the user-allocation step, the subcarriers are allocated to the users within the group using the greedy algorithm to maximize the throughput. The proposed algorithm is specifically suitable for non-real-time applications. According to the required average fairness index in the system and the maximum allowable waiting time, it is possible to find the proper group size in the proposed two-step subcarrier allocation.","PeriodicalId":253546,"journal":{"name":"VTC Spring 2009 - IEEE 69th Vehicular Technology Conference","volume":"90 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133821632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 14

A Performance Study of Bandwidth Measurement Tools over Mobile Connections 移动连接上带宽测量工具的性能研究

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073327

Erik Bergfeldt, S. Ekelin, J. Karlsson

{"title":"A Performance Study of Bandwidth Measurement Tools over Mobile Connections","authors":"Erik Bergfeldt, S. Ekelin, J. Karlsson","doi":"10.1109/VETECS.2009.5073327","DOIUrl":"https://doi.org/10.1109/VETECS.2009.5073327","url":null,"abstract":"The knowledge of the present available bandwidth on a network path is essential in numerous contexts, such as network management and streaming applications. A network path nowadays often contains at least one wireless link. This is obviously true for mobile users having a wireless connection to the Internet through a laptop or mobile terminal. The existing tools for measuring end-to-end available bandwidth are developed and optimized for paths with only guided media links. Since the characteristics for wired links and radio links differ in many aspects, such as fluctuations in capacity and stability, the network tools need to be evaluated also for network paths containing wireless links. In this investigation we have performed experiments over a high-speed downlink UMTS channel. This makes the present paper unique in the sense that it evaluates and analyzes the applicability of available-bandwidth measurement tools over a radio interface in a wide-area mobile communication network. For the experiments, a commercial mobile network has been used. The measurements show that it is feasible to achieve reliable estimates under certain circumstances. However, some cases pose challenges which motivate further studies.","PeriodicalId":253546,"journal":{"name":"VTC Spring 2009 - IEEE 69th Vehicular Technology Conference","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133795608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

BICM-ID Using Extended Mapping and Repetition Code with Irregular Node Degree Allocation 基于不规则节点度分配的扩展映射和重复码BICM-ID

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073423

Danfeng Zhao, Axel Dauch, T. Matsumoto

引用次数: 16

On the Analysis of Combined Synchronization Error Effects in OFDM Systems OFDM系统中联合同步误差效应分析

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073724

Wen-Long Chin, Sau-Gee Chen

引用次数: 8

Investigation on Optimum Radio Link Connection Using Remote Radio Equipment in Heterogeneous Network for LTE-Advanced LTE-Advanced异构网络中使用远程无线电设备的最佳无线电链路连接研究

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073617

A. Morimoto, M. Tanno, Y. Kishiyama, K. Higuchi, M. Sawahashi

引用次数: 18

Cooperative Control for Antenna Array Calibration in OFDMA/TDD Systems OFDMA/TDD系统中天线阵列校准的协同控制

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073465

Y. Hara, Y. Yano, H. Kubo

引用次数: 3

A Geographic-Based Approach to Relay Selection for Wireless Ad Hoc Relay Networks 基于地理的无线自组织中继网络中继选择方法

VTC Spring 2009 - IEEE 69th Vehicular Technology Conference Pub Date : 2009-04-26 DOI: 10.1109/VETECS.2009.5073295

Chin-Liang Wang, S. Syue

{"title":"A Geographic-Based Approach to Relay Selection for Wireless Ad Hoc Relay Networks","authors":"Chin-Liang Wang, S. Syue","doi":"10.1109/VETECS.2009.5073295","DOIUrl":"https://doi.org/10.1109/VETECS.2009.5073295","url":null,"abstract":"In this paper, we propose a novel relay selection scheme based on geographical information, aiming to minimize the symbol error probability (SEP) for wireless ad hoc relay networks. The proposed scheme utilizes only the source-relay and relay-destination distances as selection criteria to choose the best relay. In particular, such geographical information is often available during network initialization. Thus, the proposed scheme does not need extra procedures to examine which relay has the best channel quality and, hence, reduces significantly the computational complexity. By contrast, most existing relay selection schemes rely on strict channel state information (CSI) and coherent time intervals, drastically increasing the difficulty in practical realizations, especially for large relay networks in which the fading channels are sufficiently fast-varying. In our scheme, the accuracy of the distance information is the main factor resulting in non-best relay selection. An ideal scheme (in which the distances between nodes are exact) and a practical scheme (in which there exists distance estimation errors) will be discussed respectively. Simulation results demonstrate the proposed relay selection method can efficiently improve the SEP performance and outperform the random relay selection scheme.","PeriodicalId":253546,"journal":{"name":"VTC Spring 2009 - IEEE 69th Vehicular Technology Conference","volume":"194 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124335388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 26