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Given a wireless network topology, a maximum number of users with specified Quality of service “QoS” requirements, including delay constraints, are allowed to transmit and receive data. Therefore, the best solution is to establish a partition of radio resources that provides a minimum quality for each user in the network. If all users can not be served in the same time, it is important to classify...
In the case of the Ubiquitous Robot, the robot elements such as sensor, controller and actuator are distributed in the environment. This system aims at supporting robots and human beings by enabling their cooperation. In order to get high customizability, modularized robot elements are desired. For this reason, it is preferred that the functionality of each element is small. When one promotes the...
Power optimization of wireless network cards plays a significant role in the development of mobile and pervasive computing. However current wireless power management often substantially degrades performance when used with interactive applications, which account for a large fraction of software usage on modern mobile devices. We observed that user initiated interface event drives the execution of interactive...
This paper addresses the multicast handover in the wireless networks based on the Proxy Mobile IPv6 (PMIP). The existing PMIP-based multicast schemes tend to induce severe packet losses, large handover delays and unnecessary data transmissions during handover. To overcome these problems, we propose the use of Multicast Handover Agent (MHA) for fast handover. In the proposed scheme, called PMIP-MHA,...
Quality of Service (QoS) of video streaming service over wireless and mobile network is determined by many intermingled factors. Some of the factors can be adjusted. Video resolution, audio rate, and bandwidth are among of them. Other factors are not fully controllable such as network throughput, delay, and packet lost probability. In order to increase user satisfaction, efforts to make better quality...
We consider the sizing of network buffers in IEEE 802.11-based networks. Wireless networks face a number of fundamental issues that do not arise in wired networks. We demonstrate that the use of fixed-size buffers in 802.11 networks inevitably leads to either undesirable channel underutilization or unnecessary high delays. We present two novel dynamic buffer-sizing algorithms that achieve high throughput...
Supporting real-time traffic in a wireless network is a challenging task due to the high probability of errors and to the interference that can be provoked by other networks in the same area. There may be situations in which alien traffic is present by default and communication systems have to deal with difficulty by adapting their characteristics to provide the highest possible level of timing guarantees...
This paper investigates a TCP proxy that splits a TCP connection into two parts consisting of a wireless link and a wired network. The TCP proxy is effective for improving TCP performance in such a heterogeneous network including a wireless link, on which transmission errors occur. This paper describes how the TCP proxy produces large size forward data due to a packet loss on the wireless link. It...
Forward error correction (FEC) is one popular error control technique to protect the video bitstream by encoding the redundancies to recover the source information errors/losses. However, the FEC redundancy trades additional bandwidth consumption to protect video data, and therefore the wireless channel properties such as burst errors and limited bandwidth impair the FEC efficiency. In this paper,...
Currently, more and more research work has been done for the optimization of TCP performance in wireless networks. The majority of these schemes proposed are trying to optimize the system within the single layer. Obviously, jointly considering the interaction between transport layer and other layers, it may bring the improvement for TCP performance. In this paper, we propose a novel approach using...
It is difficult to provide QoS guarantees for streams in wireless network based on IEEE802.11 DCF because of limited bandwidth. Taking CBR traffic as example, we studied the traffic performance with different parameters in this paper. The results show that for an overloaded network, the traffic with longer packet size has greater throughput. Since the MAC layer performs the same competitive algorithm,...
In the article, we propose a adaptive FEC algorithm implemented in the Access Point (AP) to improve the quality of progressively compressed 3D models transmission over wireless networks(such as IEEE 802.11).Most FEC-based error control algorithms, which add redundant data to transmission data in a fixed number. However, most are unable to successfully hide the effects of burst losses (periods with...
This paper focuses on a comparative statistical analysis of the performance of VoIP calls under various situations, namely, during a handover and under different background traffic conditions at a wireless access point (AP). Using empirical-based measurements, it demonstrates that these network conditions exhibit distinct statistical behaviour, in terms of SNR, packet losses and end-to-end delays,...
Network-assisted diversity multiple access (NDMA) was recently developed to resolve collision and achieve high throughput. The blind NDMA method using independent component analysis (ICA), named ICA-NDMA, has been shown to overcome the difficulties of synchronization and orthogonal identification codes required by the training-based NDMA protocols. In this paper, we propose a novel blind collision...
This paper studies the problem of utility maximization for clients with delay based QoS requirements in wireless networks. We adopt a model used in a previous work that characterizes the QoS requirements of clients by their delay constraints, channel reliabilities, and timely throughput requirements. In this work, we assume that the utility of a client is a function of the timely throughput it obtains...
This paper presents a distributed Functional Electrical Stimulation architecture based on a wireless network, for therapeutic training of disabled patients. On this distributed architecture, a global controller can pilot a set of stimulation and acquisition units and modify dynamically stimulation and acquisition parameters. This solution intend to be a tool for researchers and therapist to develop...
This paper proposes a new backoff algorithm to enhance both the delay and the throughput of the Distributed Coordination Function (DCF) in the IEEE 802.11 based wireless networks. The proposed algorithm, which is named as the Estimation-based Backoff Algorithm (EBA), observes the number of the idle slots during the backoff period in order to estimate the number of active nodes in the network. Especially,...
A mobile ad hoc network is a wireless network without any fixed infrastructure or centralized control. Due to the infrastructure-less mode of operation, mobile ad-hoc networks are gaining popularity. In order to cover a wider area with less fixed infrastructure, sometimes the ad hoc network may be combined with a wired one to form a hybrid network. In such a combined network, in order to transfer...
Although TCP is one of the key protocols of the Internet infrastructure, it is not optimized for either wireless environment or multimedia streaming applications. It fails to meet the service requirement of streaming applications because of its strict adherence to congestion control. Besides, non-congestion packet loss fools TCP to slow down its sending rate over wireless links. Fast TCP and TCP Westwood+...
Shrinking process tolerances due to decreasing device sizes and increasing chip complexity in semiconductor manufacturing are motivating efforts to improve methods of equipment data acquisition (EDA). Prior work shows that the lack of precise time-stamping and clock synchronization is a critical hindrance to reliable data acquisition and real-time process control systems. The ultimate goal in the...
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