全文获取类型
收费全文 | 1086篇 |
免费 | 65篇 |
国内免费 | 12篇 |
专业分类
化学 | 2篇 |
综合类 | 4篇 |
数学 | 3篇 |
物理学 | 15篇 |
无线电 | 1139篇 |
出版年
2023年 | 6篇 |
2021年 | 3篇 |
2020年 | 15篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 14篇 |
2016年 | 22篇 |
2015年 | 29篇 |
2014年 | 50篇 |
2013年 | 53篇 |
2012年 | 79篇 |
2011年 | 72篇 |
2010年 | 77篇 |
2009年 | 131篇 |
2008年 | 102篇 |
2007年 | 131篇 |
2006年 | 108篇 |
2005年 | 87篇 |
2004年 | 61篇 |
2003年 | 57篇 |
2002年 | 25篇 |
2001年 | 14篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有1163条查询结果,搜索用时 203 毫秒
51.
In this paper, we present MPARC (Multi-Priority Admission and Rate Control), a novel joint admission control and rate policing protocol for multi-priority ad hoc networks. MPARC is based on our novel bandwidth allocation model, which captures the bandwidth allocation for saturated, unsaturated and semi-saturated networks. MPARC guarantees that the throughput of admitted realtime flows will not decrease due to later arriving realtime flows with equal or lower priorities or due to best effort flows. MPARC achieves this goal by performing accurate admission control on every newly arriving realtime flow and appropriate rate policing on all best effort traffic. Through simulation, we demonstrate that MPARC has better performance than existing approaches. 相似文献
52.
53.
Jang-Ping Sheu Chih-Min Chao Wei-Kai Hu Ching-Wen Sun 《Wireless Personal Communications》2007,43(2):185-200
In multihop wireless ad hoc networks, it is important that all mobile hosts are synchronized. Synchronization is necessary
for power management and for frequency hopping spread spectrum (FHSS) operations. IEEE 802.11 standards specify a clock synchronization
protocol but this protocol suffers from the scalability problem due to its inefficiency contention mechanism. In this paper,
we propose an automatic self-time-correcting procedure (ASP) to achieve clock synchronization in a multihop environment. Our
ASP has two features. First, a faster host has higher priority to send its timing information out than a slower one. Second,
after collecting enough timing information, a slower host can synchronize to the faster one by self-correcting its timer periodically
(which makes it becoming a faster host). Simulation results show that our ASP decreases 60% the average maximum clock drift
as compared to the IEEE 802.11 and reduces 99% the number of asynchronism in a large-scale multihop wireless ad hoc networks. 相似文献
54.
Design of an enhanced access point to optimize TCP performance in Wi-Fi hotspot networks 总被引:1,自引:0,他引:1
In the last years, the number of Wi-Fi hotspots at public venues has undergone a substantial growth, promoting the WLAN technologies
as the ubiquitous solution to provide high-speed wireless connectivity in public areas. However, the adoption of a random
access CSMA-based paradigm for the 802.11 MAC protocol makes difficult to ensure high throughput and a fair allocation of
radio resources in 802.11-based WLANs. In this paper we evaluate extensively via simulations the interaction between the flow
control mechanisms implemented at the TCP layer and the contention avoidance techniques used at the 802.11 MAC layer. We conducted
our study considering initially M wireless stations performing downloads from the Internet. From our results, we observed that the TCP downlink throughput
is not limited by the collision events, but by the inability of the MAC protocol to assign a higher chance of accessing the
channel to the base station. We propose a simple and easy to implement modification of the base station’s behavior with the
purpose of increasing the TCP throughput reducing useless MAC protocol overheads. With our scheme, the base station is allowed
to transmit periodically bursts of data frames towards the mobile hosts. We design a resource allocation protocol aimed at
maximizing the success probability of the uplink transmissions by dynamically adapting the burst length to the collision probability
estimated by the base station. By its design, our scheme is also beneficial to achieve a fairer allocation of the channel
bandwidth among the downlink and uplink flows, and among TCP and UDP flows. Simulation results confirm both the improvement
in the TCP downlink throughput and the reduction of system unfairness. 相似文献
55.
56.
57.
IEEE802.16e标准在继承802.16d固定宽带无线接入技术优点的基础上,增加了对移动性的支持。文中介绍了802.16e标准的协议模型,给出了以802.16e为基础的宽带无线城域网技术WiMAX的网络架构;主要针对802.16e的移动性管理进行了探讨,重点讨论了ASN内切换和ASN间切换的过程。 相似文献
58.
Kenan Xu Quanhong Wang Hossam Hassanein 《International Journal of Communication Systems》2005,18(7):619-637
This paper proposes a multi‐dimensional Markov model to analyse the performance of the IEEE 802.11e EDCF MAC protocol. Based on this model, we present extensive performance evaluation in terms of throughput, throughput ratios, and access delay of flows of distinct priorities under RTS/CTS mode. We also provide quantitative analysis of the impact of prioritized parameters, i.e. Arbitration InterFrame Space (AIFS), Contention Window (CW) on Quality of Service (QoS) differentiation. The accuracy of the proposed model is verified by means of comparing the numerical results obtained from both analytical model and simulations. Our research can be used as a guideline for the prediction of how flows belonging to a certain Traffic Category (TC) perform with their TC‐specific parameters, as well as designing EDCF‐based WLANs and tuning the parameters to achieve the desirable differentiated QoS objectives. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
59.
详细分析了WLAN(无线局域网)的最新安全标准IEEE 802.11i,包括标准体系结构、接入认证和访问控制以及加密机制;同时,分析了该标准的网络认证与授权、密钥生成与管理和数据加密机制;最后指出了WLAN安全领域需要进一步研究的课题及802.11i目前仍存在的问题. 相似文献
60.