Least-squares second-order polynomial filter and fixed-point smoother are derived in systems with uncertain observations, when the variables describing the uncertainty are non-independent. The proposed estimators do not require the knowledge of the state-space model of the signal. The available information is only the moments, up to the fourth one, of the involved processes, the probability that the signal exists in the observations and the (2,2) element of the conditional probability matrices of the sequence describing the uncertainty.

We fabricated 1.3µm AlGaInAs inner-stripe laser diodes (LDs), employing a GaInAsP waveguide layer and an n-InP current blocking layer. We compared the effects of the thickness of n-InP current blocking layer. A blocking layer with 500nm thick restricts the leakage current significantly. The inner-stripe LD was compared with the conventional ridge LD. I-L characteristics of both types of LDs were measured. Threshold currents of the inner-stripe LD and the ridge LD were 8.5 and 10.6mA, respectively. A threshold current of the inner-stripe LD is smaller than that of ridge LD. And the resistance of the inner-stripe LD was a few ohms lower than that of the ridge LD. Output power of 88mW was obtained at 200mA with 300µ m-long cavity. This was twice the power of a conventional ridge laser. The characteristic temperature of the inner-stripe LD was obtained 76 K from 20 to 85. We obtained a good linearity up to 100mA at 85. Therefore the inner-stripe LD has an advantage of high power devices.

Recently, Hwang and Yeh demonstrated that Peyravian-Zunic's password authentication scheme is vulnerable to several attacks, and then proposed a modified version. In this letter, we show that Hwang-Yeh's scheme still has several weaknesses and drawbacks.

Assume that each edge e of a graph G is assigned a list (set) L(e) of colors. Then an edge-coloring of G is called an L-edge-coloring if each edge e of G is colored with a color contained in L(e). In this paper, we prove that any series-parallel simple graph G has an L-edge-coloring if |L(e)| max{3,d(v),d(w)} for each edge e = vw, where d(v) and d(w) are the degrees of the ends v and w of e, respectively. Our proof yields a linear algorithm for finding an L-edge-coloring of series-parallel graphs.

In this paper, we present an Internet personal live-broadcasting server system. Our solution is not only for experts but also for amateur users who want to broadcast using simple multimedia equipment. For scalable broadcasting services, we developed multiple-channel establishment and channel expansion. Concurrent services for a large number of broadcasting channels are effectively provided. Also, the capacity of channels can be expanded as the number of participants increases. Furthermore, for the sake of complete live broadcasting with high-quality transmission, the system supports both TCP (transmission control protocol) and UDP (user datagram protocol) according to the status of network environments as well as the received packet loss in the user system. The performance of the system is effectively evaluated at such practical commercial sites as well-known community and E-business sites.

Many congestion control mechanisms have been proposed to solve the problems of a high loss rate and inefficient utilization of network resources in the present Internet. This problem is caused by competition between traffic flows while the network is congested. Differentiated Services (DiffServ) architecture permits the allocation of various levels of traffic resource requirements needed for Quality of Service (QoS). Random Early Detection (RED) is an efficient mechanism to pre-drop packets before actual congestion occurs, and it is capable of introducing a random early packet dropping scheme, and based on the queue length in reaching a certain degree of fairness for resource utilization. However, it still suffers from a lack of robustness among light traffic load, or in heavy traffic load using fixed RED parameters. In this paper, we modified the RED scheme and proposed a novel adaptive RED model, which we named the OURED model, to enhance the robustness of resource utilization so that it could be utilized in the DiffServ edge router. The OURED model introduces two additional packet dropping traces, one is Over Random Early Detection (ORED), which is used to speed up the dropping of packets when the actual rate is higher than the target rate, and the other one is the Under Random Early Detection (URED), used to slow down the packet dropping rate in the reverse situation. The simulation results show that OURED is not only more robust than MRED in resource utilization, but that it also can be implement efficiently in the DiffServ edge router.

Self-pulsation of Nd3+-doped fluoride fiber laser is experimentally and theoretically demonstrated using a Tm3+-doped fluoride fiber pumped at 808 nm as a saturable absorber. Self-pulsation at finite pump power predicted by linear stability analysis is confirmed through experiments, achieving a pulse width and peak power of 4.5µs and 1.5mW when the Nd3+-doped fiber was pumped at 230mW.

The generation of high repetition-rate optical pulse train using a passively mode-locked figure-8 fiber ring laser is presented. The laser employs a novel configuration incorporating a superstructure fiber Bragg grating. Pulse train with repetition rates up to 100GHz is possible and transform-limited pulses with pulsewidth below 1ps can be achieved with chirp compensation. The output pulses can further be reduced to 83fs with an external pulse compressor.

CPCH is an uplink common channel that is used by 3GPP to support reliable packet transport. In this paper, we propose a new access scheme by using the discrimination of backoff timer for providing a prioritized service. We also present a simple system model of CPCH for EPA and use it to derive mathematical results. The results show that multi-class services with different priorities can be served effectively and easily by the proposed scheme.

In recent years, information devices with network communication ability have become very popular, and many people actually own such kind of devices. Those information devices, however, do not share users' data in spite of their communication ability. This paper proposes "OCEAN: Object Communication Environment for Arbitrary Network" architecture, which provides liaison of objects stored in each device according to their profiles and situations. It eliminates redundant user operation on information devices, and enables novel communication scheme among users by sharing common objects in those devices. Furthermore, it maximizes the effective use of each device's limitation according to each environment. Finally, in this paper, we discuss our prototype of OCEAN.

In this paper, we propose the window-based congestion control mechanism using explicit feedback in TCP over ATM ABR service. The proposed scheme is based on notifying the network status as the free buffer length at the congested link to the IP station which informs the window rate by modifying the receivers' advertised window field in TCP ACK returning to the source. Results from simulation show that our proposed algorithm improves the fairness and stability of TCP connections in general network environments even if they have the different round trip times.

This paper presents an observer design methodology for a special class of MIMO nonlinear systems. First, we characterize the class of MIMO nonlinear systems that consists of the linear observable part and the nonlinear part with a block triangular structure. Also, the similarity transformation that plays an important role in proving the convergence of the proposed observer is generalized to MIMO systems. Since the gain of the proposed observer minimizes a nonlinear part of the system to suppress for the stability of the error dynamics, it improves the transient performance of the high gain observer. Moreover, by using the generalized similarity transformation, it is shown that under some observability and boundedness conditions, the proposed observer guarantees the global exponential convergence to zero of the estimation error. Finally, the simulation results for induction motor are included to illustrate the validity of our design scheme.

End-to-end delay and loss measurement is an efficient way for a host to examine the network performance. Unnoticed clock errors that influence the accuracy of the timestamp may result in fatal system errors. In this paper, we discuss the characteristics and defects of the existing clock distortion adjustment algorithms. Those algorithms are not applicable to process a long-term delay trace, which contains periodical NTP clock adjustment. Therefore, we propose a relatively robust algorithm to resolve the problem. The algorithm employs window function to partition the long-term trace into short segments, improves the precision of the estimation of the time and amount of NTP clock adjustment To evaluate the performance of our proposed algorithm, we practice it in adjusting the clock distortion of the real delay traces collected from Internet. The results indicate that our proposed algorithm has excellent effect on the removal of the clock distortion from the long-term delay traces.

A high efficient HBT MMIC power amplifier with a new on-chip bias control circuit was proposed for PCS applications. By adjusting the quiescent current in accordance with the output power levels, the average power usage efficiency of the power amplifier is improved by a factor of 1.4. The bias controlled power amplifier, depending on low (high) output power levels, shows 62(103) mA of quiescent current, 16(28) dBm output power with 7.5(35.4)% of power-added efficiency(PAE), -46(-45) dBc of adjacent-channel power ratio (ACPR), and 23.7(26.9) dB of gain

A new pilot-aided multiuser detection scheme, single code cyclic shift (SCCS) detector, is proposed in this paper for synchronous CDMA multiuser signal reception. The unique feature of the proposed detector is that a receiver can decode multiuser signals even without explicit knowledge of all signature codes active in the system. The transmitting signal from a base station to a mobile contains two separated channels: the pilot and data channels; the former consists of periodically repeated pilot symbols encoded by the same signature codes as the one spreading the latter. Both pilot and data signals for a specific mobile are sent by a base-station using quadrature and in-phase carriers at the same frequency with QPSK modulation. A matched filter bank, consisting of M correlators that match to distinct cyclic-shifted versions of a "single" signature code, is employed for "channel cyclic shift correlation function" estimation, followed by the multiuser detection algorithm based on the channel information obtained earlier. The performance of the proposed SCCS detector is evaluated and compared to decorrelating detector by computer simulations considering various multipath channels with different profiles. The results demonstrate that a synchronous CDMA joint detection can be implemented successfully without necessarily knowing all signature codes of the system.

This paper proposes a wireless scheduling algorithm that can provide the Internet with delay proportional differentiated services in wireless networks. When considering wireless network environments that include burst and location-dependent channel errors, the proposed WDPS (Wireless Delay Proportional Service) scheduling algorithm can adaptively serve packets in class queues based on the delivered delay performance for each class. The significant characteristics of the WDPS scheduler include support for a fair relative delay service, the provision of graceful throughput and delay compensations, and the avoidance of class queue-blocking problems. Simulations show that the proposed algorithm can achieve the desirable properties for providing delay proportional services in wireless networks.

We propose new language models to represent phrasal structures by patterns extracted from parse trees. First, modified word trigram models are proposed. They are extracted from sentences analyzed by the preprocessing of the parser with knowledge. Since sentences are analyzed to create sub-trees of a few words, these trigram models can represent relations among a few neighbor words more strongly than conventional word trigram models. Second, word pattern models are used on these modified word trigram models. The word patterns are extracted from parse trees and can represent phrasal structures and much longer word-dependency than trigram models. Experimental results show that modified trigram models are more effective than traditional trigram models and that pattern models attain slight improvements over modified trigram models. Furthermore, additional experiments show that pattern models are more effective for long sentences.

There is a growing demand that mobile networks should provide quality-of-service (QoS) to mobile users since portable devices become popular and more and more applications require real-time services. Providing QoS to mobile hosts is very difficult due to mobility of hosts. The resource ReSerVation Protocol (RSVP) establishes and maintains a reservation state to ensure a given QoS level between the sender and receiver. However, RSVP is designed for fixed networks and thus it is inadequate in wireless mobile networking environments. In this paper, we propose a resource reservation protocol for mobile hosts in mobile networks. The proposed protocol extends the RSVP by introducing RSVP agents in local networks to manage the reservations. The proposed protocol reduces packet delay, bandwidth overhead, and the number of RSVP messages to maintain reservation states. We examined the performance of the proposed protocol by simulation and we got an improved performance over the existing protocols.

The differentiated services (DiffServ) architecture is proposed to provide a service differentiation between traffic classes or behavior aggregates in a scalable manner. A key functional element to deploy DiffServ is traffic conditioning, more specifically traffic marker. This paper proposes an adaptive and aggregated traffic marker embodying the functions: (1) inter-connect two-rate three color markers (trTCMs), (2) estimate the aggregate rate of Assured Forwarding (AF) classes, and (3) re-mark the some parts of excessive portion of assigned link-rate per AF class queue with some down-grading probability to lower AF class. Both analysis and simulations are used to evaluate the performance of the proposed aggregate-traffic marker. The analysis of the proposed marker shows its clear service differentiation among behavior aggregates (BAs) under different traffic load conditions. Also a performance evaluation is performed through network simulation with more realistic traffics as unbalanced intensities among different BAs. Shortly, our proposed aggregate-traffic marker enables to keep the priority orders in terms of loss rate and delay/jitter among BAs in spites of varying and unbalanced traffic intensities.

Assume that each edge e of a graph G is assigned a list (set) L(e) of colors. Then an edge-coloring of G is called an L-edge-coloring if each edge e of G is colored with a color contained in L(e). It is known that any series-parallel simple graph G has an L-edge-coloring if either (i) |L(e)| max{4,d(v),d(w)} for each edge e=vw or (ii) the maximum degree of G is at most three and |L(e)| 3 for each edge e, where d(v) and d(w) are the degrees of the ends v and w of e, respectively. In this paper we give a linear-time algorithm for finding such an L-edge-coloring of a series-parallel graph G.