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Voice over Internet Protocol (VoIP) over a wireless local area network (WLAN) is poised to become an important Internet application. However, unacceptable VoIP performance in the presence of coexisting traffic from other applications is still one of the major problems standing in its development way. For this point, in this paper, a novel adapted adjustment packet segmentation method is proposed to...
Currently embedded remote monitoring technology step into a rapidly developing period. With the advancement of related technology, low cost remote monitoring system which is web-based, powerful and reliable at the same time will become the mainstream. Under this background, this paper presents a lightweight embedded remote monitoring system. The owerall system established a LAN using zensys's Z-WAVE...
After the analysis of the working principle of WAPI, its security weaknesses are pointed out: it does not securely realize the goal of identity authentication and key agreement. According to the security weaknesses, the key agreement part is improved without changing the framework of WAPI. The improved protocol is not only SK-secure but also UC-secure, thus realizing identity authentication and key...
The authentication process of wireless local area network authentication and privacy infrastructure, namely, WAI protocol, is researched and analyzed, and the security analysis is made to its the key-agreement process by using CK model. The analysis shows that: WAI can realize security attributes such as mutual key-control, key confirmation and so on, and it can also statisfy the secure goal of wireless...
In this paper, we investigate the training problem of wireless local area networks (WLANs) with downlink multi-user multiple input multiple output (DL MU MIMO) capability. We extend the 802.11 MAC protocol and propose a few training protocols at the MAC layer to support DL MU MIMO. We provide a capacity analysis based on measurement results from an 802.11n systems, evaluate the overhead of these training...
IEEE 802.11 Wireless Local Area Network (WLAN) Physical Layer (PHY) offers multiple data rates. In multi-rate WLANs, 802.11 Medium Access Control (MAC) protocol, Distributed Coordination Function (DCF), essentially provides equal transmission opportunities to each sender host, causing the degradation of system throughput due to some hosts using low rates. In this paper we propose a cross-layer link...
Cooperative communications achieve tremendous improvements in system performance. Meanwhile, it tends to change the conventional access and transmission schemes in wireless networks. Thus, CoopMAC is proposed and analyzed for fully connected WLANs. It improves the performance of the network dramatically by enabling additional collaboration from other nodes. However, how does it work in multi-hop Ad...
TCP's downlink performance during FMIPv6-enabled IEEE802.11g handoff is examined. The use of a user-initiated Handoff Notification, sent prior to handoff, is proposed. Therefore, the correspondent node is aware of the handoff-induced disruption, hence avoiding dropping the congestion window size and triggering Fast Retransmission mechanisms. During handoff, it continues to send data packets which...
For ad-hoc home networks without central coordinator, IEEE 802.11 systems merely support service differentiation. In many usage scenarios of a typical home network with applications requiring a strict quality of service (QoS), this MAC functionality is not sufficient. In order to counteract this problem, we developed in previous works a modified MAC scheme based on the IEEE 802.11 enhanced distributed...
The seamless integration of heterogeneous wireless access networks is currently one of the issues of major interest in the field of telecommunication systems. In an early future technologies like UMTS, WLAN and WiMAX will give broadband access to users that perform their voice/video calls or data sessions without knowledge of the specific technology their terminals are using, following the paradigm...
In order to imitate the channel characteristics of 802.11n WLAN, this paper analyzes channel model mechanism of Markov stochastic process and implements the extensional module of 802.11n channel in NS2. In the end, through comparing simulation results with standard TGn model, we verify the accuracy of this module which provides efficient physical layer channel simulation foundation for the research...
In this paper we focus on the concept of IEEE 802.11 DCF error frame model. Based on the analysis of the model in detail, we point out the error of the simulation algorithm of the DCF error frame model in QualNet simulation environment. Furthermore, we modify the simulation algorithm in QualNet strictly according to the specifications of the DCF error frame model. The simulation results show that...
Wireless local area networks (WLANs) provide mobility and convenience to users, the efficiency of today's WLANs are still far from satisfactory. In this paper discusses the performance of wireless Ad-Hoc networks, our main contribution is analyze transmission's power level to compare the throughput performance on simulation results. We describe NS-2 (Network Simulation) implementations for fine-tuning...
This paper presents a comparative analysis, set in Vanet scenarios and based on simulations, between the well-known IEEE 802.11p standard and an efficient slotted protocol based on RR-Aloha (MS-Aloha). Notably the chosen slotted protocol is completely distributed and based on reservation, and has been specifically designed to face issues typical of mobility, while preserving quality of service guarantee...
TCP, the facto standard used in today's Internet, has been found to perform poorly in Mobile Ad Hoc Networks (MANETs). This is exacerbated by contention with increasing UDP-based high priority multimedia traffic and the class differentiation introduced in current QoS protocols, which results into TCP starvation and increased spurious timeouts. In this paper, we propose a cross-layer TCP enhancement...
Carrier sense multiple access with collision avoidance (CSMA/CA) is one of the basic media access control (MAC) protocols specified in the IEEE 802.11 to support many stations to share a channel in the network. This paper analyzes how the performance of CSMA/CA is affected by the back-off time. We propose to use random back-off time and simulation results show that it can achieve better performance...
Wireless sensor networks have become very useful in so many applications. Applications such as grape monitoring, insect movement monitoring and etc., that allows connectivity between sensor network and Internet can solve many remote control and monitoring problems. IPv6 over low power WPAN (6lowPAN) protocols are suitable technology that can be adapted in wireless sensor network. The deployment of...
We propose a new vertical handoff method in which the number of signaling and registration processes is lowered as a result of reduced utilization of home agent and correspondent nodes while users are mobile. Throughput performance of the integrated network is improved by reducing handoff delays and packet losses. Special conditions such as boundary condition also considered. Performance and delay...
IEEE 802.11 proposed a number of standards and each one had a specific goal. They can be configured in infrastructure mode or ad hoc mode. In the study of infrastructure mode, the focus was on 802.11 b/g co-existence along with other single mode operations to analyze the throughput and traffic drop through simulation. In the study of ad hoc mode, the focus was to analyze the behavior of ad hoc networks...
One of the most important issues in wireless and mobile communication technologies is the mobility management when a mobile node moves between different access networks. Many alternative ways to realize mobility management have been proposed on different layers. In this paper we discuss the vertical handoff behavior when a mobile node moves from IEEE 802.11 network to IEEE 802.16 network and vice...
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