Search

an increase number of wireless applications consist of a network of mobile nodes moving together in high velocity, existing protocols focused on roaming of single node, and there are no mature solutions to keeping uninterrupted high-speed mobile communications for roaming the entire subnet with a moving velocity as high as a vehicle. In this paper, firstly we propose the idea of the new handover scheme based on mobile IP, and then introduce the principle and key issues for subnet mobility in networks. The station (STA), a wireless communications equipments in mobile wireless subnet, taking the access point (AP) as the gateway, implements the multiple-hop subnet mobile IP by cooperation of the home agent, the foreign agent, interior network routing agent and reused tunneling, thus to overcome the limitation of one hop between the movement node (MN) to the exit of the tunnel. A dynamic next AP scanning and finding model and a handover trigger model named Well-time is designed to provide low latency. We implement the scheme on re-designed STA and AP, the experiment shows that the new scheme enables a mobile subnet to handover seamlessly across heterogeneous wireless networks and maintains all ongoing high-speed communications with the nodes in fixed networks, when moving at a high velocity up to 50km/h. [ABSTRACT FROM AUTHOR]

Wireless communications using microwaves are increasingly important, e.g. Wi-Fi. Performance is a very relevant issue, resulting in more reliable and efficient communications. Laboratory measurements are made about several performance aspects of Wi-Fi (IEEE 802.11a, b, g) point-to-point links using available access points from Enterasys Networks (RBT-4102). Through OSI levels 3, 4 and 7, detailed results are presented and discussed, namely: latency, ICMP packet loss, TCP throughput, jitter, percentage datagram loss and FTP transfer rate. [ABSTRACT FROM AUTHOR]

Nowadays, high computing demands are often tackled by clusters of computers, each of which is basically an assembly of a growing number of CPU cores and main memory; these nodes are connected by some kind of communication network. With the growing speed and number of CPU cores, the network becomes a severe bottleneck limiting overall cluster performance. High-speed interconnects like SCI and Dolphin DX are good for alleviating this communication bottleneck, when the communication software is either based on IP or specifically adapted to the interconnect. Software written to communicate directly via Ethernet frames can not be used this way, though. In this article, we present ETHOM, a driver that implements an Ethernet interface on top of the Dolphin Express software stack. It enables the Dolphin networks SCI and DX to be used as high-speed replacement for Ethernet. Offering an Ethernet and with that an IP interface, it enhances their functionality and allows usage of layer-2 kernel functionality like interface bonding and bridging. This driver is an improvement of ETHOS, the Ethernet over Sockets driver, delivering lower latencies at the cost of higher CPU load. By means of various measurements, we show that ETHOM with SCI or DX offers a two-fold increase in communication performance over Gigabit Ethernet. [ABSTRACT FROM AUTHOR]

This working prototype system can detect handwritten digits from a scanned image of an input form by using Neural network technique. Hand writing recognition and Image detection through this methodology is very fast and effective as compared to old fashioned image pixel comparison methodology, which is comparably slow. In the initial phase for handwritten digit input we have designed a form which can take hand writing samples from different people. The form must have specific format so user can give multiple input in 10 rows, and hand write 0,1,2,3,4,5,6,7,8,9 in the corresponding sampling cells ( rows* columns). The cell must also have width according to your requirement (e.g set it to 20*2 pixels). Once the blank forms have been manually filled by different people then scan these forms with the help of scanner. So now we have images of hand writing samples of digits. In the 2nd phase, we use image slicing technique to slice sample image of size 16*16 pixel for each digit from the scanned form [1]. Each scanned form image will make nearly 100 images of 16*16 pixels. Repeat the same step for all scanned sample forms and place all these 16*16 pixel images ( sample pool) into one location. In the detection phase, a three-layered neural network is used: After training, the obtained weight and bias are stored for each digit sequence(signature). It is now possible to identify the meaning of any hand written digit with the help of AI engine. So now when ever any handwritten digit will be given as sample input in to the system , the output array will automatically give the digit whose corresponding match value is detected. The above process is a blueprint of human cognitive thinking process. [ABSTRACT FROM AUTHOR]

This paper examines the bit-error rate (BER) for an optical direct-detection code-division multiple-access (OCDMA) system employing a novel prime code family, hereby referred to as 'Double-Padded Modified Prime Code (DPMPC)' for the spreading and de-spreading operations in addition to coherent homodyne dual-balanced detection. As a coherent modulation, binary phase-shift keying (BPSK) format is deployed where the phase is modulated by either an external phase-modulator or injection-locking methods. The phase limitation and the performance for both phase-modulations including multiple access interferences (MAI) in a shot-noise limited regime are studied and moderate penalty associated with the limited phase excursion is revealed. [ABSTRACT FROM AUTHOR]

Describes the design and experimental implementation of a high-speed transputer-based memory subsystem for the HTPNET transport protocol. Discussion on the data transfer design; Design of HTPNET Protocol Engine; Prototype implementation of the HTPNET on an off-shelf transputer platform.

Describes the implementation of a high performance Remote Procedure Call (RPC) communication network interface which is compatible with existing operating systems. Discussion on the Advanced Networked Systems Architecture (ANSA); Extraction of the RPC mechanism Remote Execution Protocol (REX) from the UNIX ANSA environment; Effect of the optimization of REX and User Datagram Protocol packet code for outgoing and incoming packets.