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We derive a new lower bound for the bandwidth of a graph that is based on a new lower bound for the min-cut problem. Our new semidefinite programming relaxation of [...]

The bandwidth packing problem (BWP) concerns the selection of calls from a given set and the assignment of one path to each selected call. The ultimate aim of the BWP [...]

We study departures from network neutrality through implementing a quality of service tiering regime in which an Internet service provider charges for prioritization on a nondiscriminatory basis. We find that [...]

A study was conducted to propose self-adaptive and efficient bandwidth allocation solutions. This solution features an optical line terminal (OLT) which allocates bandwidth among the optical network units (ONUs) in an efficient manner. The importance of upstream dynamic bandwidth allocation for Gigabit Passive Optical Networks (GPONs) is also discussed.

Nowadays, the demand of transmitted information over networks increase rapidly and the demand for steady bandwidth seems to be out of control. Particularly organizations need to provide updated data to users that might be geographically remote and handling a vast amount of requested data distributed in multiple sites. Problem statement: Replication in distributed environment has become increasingly popular due to its high degree of availability, fault tolerance and enhance the performance of a system. These advantages of replication are important because it enables organizations to provide users with access to current data anytime or anywhere even if the users are geographically remote. However, this way of data organization also introduces low data consistency among replicas when changes are made during transactions. The need to have a system to monitor this data replication arises. Approach: Read-One-Write-All Monitoring Synchronization Transaction System (ROWA-MSTS) has been developed to solve this problem by using Rapid Application Development (RAD). Results: ROWA-MSTS helped to monitor the replicated data distribution over multiple sites while maintaining the data consistency. Conclusion: Results showed that ROWA-MSTS solved the distributed concurrency transactions and guarantees the data consistency in distributed systems. Key words: Distributed system, replication, consistency, transaction, INTRODUCTION In the world where internet does all the business nowadays, the demand of transmitted information over networks increase rapidly and the demand for steady bandwidth seems to be out [...]

Recently, along with the booming of research and production of a CMOS integrated biosensing system (IBS), the ultralow current-mode amplifier (ULCA), which serves for the preamplification of biosensor signals, has been in high demand in areas like ultralow biocurrent analysis and detection, deoxyribonucleic acid probing and surveying systems, etc. in this brief, a novel ULCA is presented and implemented in SMIC 0.18-[micro]m CMOS technology by elaborately considering gain, bandwidth, noise, and offset issues. The experimental results show that the proposed ULCA can completely satisfy the specifications of IBS and stably provide the current gain of 19.9 dB, 3-dB bandwidth of 15 kHz, and input range of -0.4 to 0.4 mA, with only 1.5 nA of dc quiescent current. The input-referred offset and the noise current are 96.6 pA and 37.6 pArms, respectively. Index Terms--Bandwidth, integrated biosensing system (IBS), mismatch, noise, offset, subthreshold, ultralow current-mode amplifier (ULCA).

Uniplanar 180[degrees] hybrids are basic building blocks in uniplanar technology. In this paper, a new rigorous analysis of a uniplanar 180[degrees] magic-T hybrid based on an air-bridged coplanar cross is performed. The analysis proposed is multimodal since it takes into account the coplanar even and odd fundamental modes simultaneously. From this analysis, a complete circuit model for the hybrid is extracted, and the conditions for ideal performance are derived. This new multimodal model is necessary for the design of the hybrid, and allows a quantitative analysis of its performance, notably bandwidth, isolation, and return loss under any actual loading condition. It has been used to design and implement a 180[degrees] hybrid on alumina with a working frequency of 15 GHz. A very good agreement between simulation and measurement is obtained. The experimental results prove a frequency-independent phase-shift behavior with a measured phase error less than [+ or -] 2[degrees]. Index Terms--Coplanar waveguide (CPW) cross, magic T, multimodal models, 180[degrees] hybrid, uniplanar circuit.

To realize any coupled-line ring hybrid without any restriction on coupling power, a set of coupled-line sections with two shorts was synthesized using one- and two-port equivalent circuits, and design equations were derived to yield perfect matching regardless of the coupling power. Based on the design equations, a new modified R-type transmission-line equivalent circuit is suggested. It consists mainly of a set of coupled-line sections and can be used to reduce a transmission-line section, especially when the electrical length is greater than 180[degrees]. Therefore, the 270[degrees] transmission-line section of a conventional ring hybrid can be reduced to less than 90[degrees]. To verify the performance of the modified one, two kinds of simulations were performed: in the first, the electrical length of the coupled-line sections was held constant, in the second, the coupling coefficient was held constant. Simulated bandwidths of the resulting small transmission lines depended strongly on coupling power. Using modified and conventional R-type transmission-line equivalent circuits, a small wideband coupled-line ring hybrid (SWCLRH) was designed. Compared to the conventional ring hybrid, the SWCLRH has much wider bandwidth, but is less than one-third as large. To test the method, a microstrip SWCLRH with a total transmission-line length of 220[degrees] was fabricated and tested. Measured [S.sub.21], [S.sub.41], [S.sub.23], and [S.sub.43] were -2.78, -3.34, -2.8, and -3.2 dB, respectively, at a design center frequency of 2 GHz. Matching and isolation with less than -20 dB were achieved in more than 20% fractional bandwidth. Index Terms--Coupled transmission-line sections with two shorts, modified II-type transmission-line equivalent circuit, small wideband coupled-line ring hybrids (SWCLRHs), wideband coupled-line ring hybrids (CLRHs).

Microstrip-line-fed printed wide-slot antenna with a fractal-shaped slot for bandwidth enhancement is proposed and experimentally studied. By etching the wide slot as fractal shapes, it is experimentally found that the operating bandwidth can be significantly enhanced, and the relation between the bandwidth and the iteration order (IO) and iteration factor (IF) of the fractal shapes is experimentally studied. Experimental results indicate that the impedance bandwidth, defined by -10 dB reflection coefficient, of the proposed fractal slot antenna can reach an operating bandwidth of 2.4 GHz at operating frequencies around 4 GHz, which is about 3.5 times that of a conventional microstrip-line-fed printed wide-slot antenna. It also achieved a 2-dB gain bandwidth of at least 1.59 GHz. Index Terms--Bandwidth enhancement, fractal antenna, microstrip-line-fed antenna, slot antenna.

Admission control plays a very important role in guaranteeing the quality-of-service (QoS) in wireless mesh networks (WMNs). In this paper, based on the channel and hidden terminal information, we first estimate the available bandwidth in the operation of medium access control (MAC). We then design an admission control algorithm (ACA) at the MAC layer to address the QoS issue for real-time and nonreal-time traffic. For real-time traffic, all nodes on a route make an admission control decision based on the estimated available bandwidth. For the nonreal-time traffic, a rate adaptation algorithm is proposed to adjust the sending rates of sources to prevent the network from entering the congestion state. Finally, through extensive simulations, we demonstrate the effectiveness of our algorithm. Index Terms--Admission control, medium access control (MAC), quality of service (QoS), wireless mesh networks (WMNs).

This brief presents a new passive element called Pi coil for bandwidth extension. Its transfer function and detailed design tables are given. Based on ideal elements, the proposed Pi coil can achieve the largest bandwidth extension ratio compared to its counterpart, i.e., T coil, and other similar bandwidth-enhancing techniques. In addition, the input return loss (S11) is much improved by using this technique. On-chip implementation methods of the T coil and the Pi coil are also investigated in this brief. Index Terms--Bandwidth extension, inductor, Pi coil, T coil.

Multimode signal transmission concept is employed in this paper to increase the channel capacity of a substrate integrated waveguide (SIW) interconnect. In order to generate two uncoupled channels without adding an additional physical link, [TE.sub.10] and [TE.sub.20] modes of an SIW interconnect are harnessed as signal carriers. To excite these two orthogonal modes simultaneously, a multimode double launcher is proposed and characterized. It is shown that the performance of the launcher is limited by the coupling between the two mode launchers (transitions). Therefore, a method for improving port isolation is suggested, which results in increasing the channel bandwidths. A balun structure based on an SIW is presented and included in the multimode waveguide in order to efficiently excite the [TE.sub.20] mode. Ultimately, the multimode waveguide with the optimized transitions is used in a parallel data transmission system demonstrating excellent transmission quality for the data rate of a 1-Gb/s/channel. Index Terms--Balun, higher order mode, multimode transmission, parallel signaling, substrate integrated waveguide (SIW), waveguide transitions.

This paper describes the design of embedded-grating [n.sup.+]-i-[n.sup.+] traveling-wave photodetectors (TWPDs). In the ideal case of perfect electrically matched photodetectors, the TWPD bandwidth is determined by the velocity mismatch between the group velocity of the optical beam and the phase velocity of the electrical photogenerated signal, as well as by the attenuation of the RF signal propagating along the electrodes. Since the group velocity is determined once the layer's thickness is selected, which, in turn, is optimized for coupling the light into the photodetector, only an accurate electrode design allows for the velocity matching. In this paper, we propose a new structure that utilizes a grating integrated within a single-mode waveguide in order to tailor the optical group velocity and match it to the phase velocity of the photogenerated signal. Index Terms--Bandwidth, grating, photodiode, semiconductor device, traveling-wave photodetector (TWPD).

The problem of optimizing access and bandwidth sharing among Transmission Control Protocol (TCP) connections in the mobile digital video broadcasting return channel via satellite (DVB-RCS) is tackled in this paper. After sketching the general system architecture, we explicitly deal with the dynamic assignment of bandwidth to TCP connections on the return link, which is accomplished by a network control center (NCC) placed onboard the satellite. Mobile users access the satellite in multifrequency time-division multiple access (MF-TDMA), whereas they receive data from the NCC in time-division multiplexing (TDM). Two different techniques, based on deterministic and random access, are compared in terms of bandwidth usage and average completion time per connection, when the mobile user acts as both server and client. In the server case, to increase the TCP throughput, both packet-level forward error correction (FEC) on data sent by mobile users and a duplicated and delayed acknowledgment technique for TCP acknowledgment traffic from the NCC to the mobile users are applied. An analysis of the packet losses and a simulation campaign of file transfers by employing a realistic channel model has been carried out. The results of the analysis show the convenience of adopting a technique, in addition to the optimal data redundancy in different cases, such as the server or client role of users, their willingness to pay, the file size, and the environment type. Index Terms--Demand assignment multiple access (DAMA), digital video broadcasting return channel via satellite (DVB-RCS), diversity slotted ALOHA (DSA), satellite mobile environment, Transmission Control Protocol (TCP) throughput.

In this paper we evaluate outage performances of multirelay amplify and forward (AF) transmission over fading channels. We focus on the uplink of a two-hop based network where N (with N [greater than or equal to] 1) single antenna relay stations (RSs) serve as non-regenerative repeaters for the message transmitted by a single antenna source node (or mobile station MS). Performances are derived at high SNR for arbitrary fading distributions over each cooperative link. In Rayleigh fading the high price of cooperation in terms of signalling (e.g. during MS-to-RSs transmissions and control messages broadcasts) causes a significant loss in spectral efficiency. Instead, provided that the RSs can be strategically positioned to benefit from a channel with marginal diffusive fading component compared to Rayleigh, this paper shows that this loss in efficiency can be significantly alleviated depending on the particular propagation environment. Closed form conditions on the fading statistics for the relayed links are derived to guarantee that collaborative transmission performs as if the MS node would benefit from the same diversity and bandwidth efficiency provided by multi-antenna transmission. The proposed conditions are computed for arbitrary distributed fading for the relays-to-BS link and are specialized for Rice faded RSs-to-BS links. Index Terms--Cooperative diversity, amplify and forward relaying, relay deployment, Rice fading.

The performance of non-data-aided feedback-loop symbol timing synchronization operating with the raised-cosine (RC) and the "better than" raised-cosine (BTRC) pulses is investigated. The individual effects of additive channel noise, self-noise, and their product on the variance of the jitter are studied for the two pulses. The BTRC pulse is shown to have better synchronization performance than the conventional RC pulse, except when the signal-to-noise ratio is very large and the excess bandwidth is large. Furthermore, in the case where a prefilter removing serf-noise is employed, the BTRC pulse always has a performance gain over the RC pulse. The gain is, for example, as much as 1.4 dB for excess bandwidth of 0.35 without a prefilter and is larger when the excess bandwidth is smaller or a prefilter is employed. Index Terms=Better than" raised-cosine pulse, non-data-aided symbol timing-error detection, raised-cosine pulse.

In this paper, a printed microstrip-line-fed rhombus slot antenna with a pair of parasitic strips is presented. With the use of these parasitic elements along the microstrip feed line, bandwidth enhancement for wideband operation can be obtained. From experimental results, the measured impedance bandwidth, with a 10 dB return loss, can operate from 1.80 to 6.09 GHz which is wider than a conventional microstrip-line-fed, printed rhombus slot antenna without parasitic elements. By selecting proper dimensions of parasitic strips, the proposed antenna can provide PCS, IMT-2000, and WiMAX multiband operations for various wireless communication services. Details of the proposed antenna are described, and experimental results are presented and discussed. Index Terms--Bandwidth enhancement, microstrip-line-fed antennas, printed slot antennas.

This brief presents an adaptive-bandwidth (BW) phase-locked loop (PLL) that retains the optimal jitter performance over a wide frequency range via continuous background frequency calibration. The effective center frequency of the voltage-controlled oscillator (VCO) is calibrated by adjusting the feedforward division factor while a dual-PLL architecture hides the switching transients. As a result, the core ring oscillator only needs to operate over a narrow frequency range of 2 : 1 that is optimal for the jitter, supply sensitivity, and charge pump current mismatch over process, voltage, and temperature (PVT) conditions. The prototype PLL was fabricated in a 0.13-[micro]m CMOS process, consumed 36 mW of power, and occupied 1.1 x 0.46 [mm.sup.2] of area. The measured root-mean-square (RMS) tracking jitter was less than 0.2% of the reference clock period for the wide range of output frequency (2 MHz-1 GHz) and multiplication factor ([2.sup.0-9]), which supports that the PLL BW scales adaptively with the reference frequency. Compared to a PLL without frequency calibration, the proposed PLL demonstrated the jitter reduction up to 80%. Index Terms--Adaptive bandwidth (BW), automatic frequency calibration (AFC), CMOS, phase-locked loop (PLL).

This paper presents a novel design for frequency-selective limiters based on reflection-mode nonlinear bandstop filters. This technique enables the use of low-Q lossy resonators for high-Q bandstop filter applications. Frequency-selective limiters described here achieve fast switching, high levels of power limiting, and flexible channel bandwidth. The prototype for a third-order device indicates 2-dB insertion loss for low RF powers. At high RF powers, it demonstrates 18-dB limiting level, 3-dBm limiting threshold, and 300-MHz limiting bandwidth. The switching speed is less than 10 ns, thus the spike leakage is minimized. The single-channel limiters are cascaded to provide limiting in wideband channels. The multichannel device is able to compress the dynamic range of the signals over 30 dB. Index Terms--Bandstop filters, limiting, microstrip resonators, microwave limiters, nonlinear filters.

This paper considers an output feedback learning control for a class of uncertain nonlinear systems with flexible components. The distinct time delay caused by system flexibility leads to the phase lag phenomenon and low system bandwidth. Therefore, the tracking problem of such systems is very difficult and challenging. To improve the tracking performance of such systems, an iterative learning control scheme using the Fourier neural network (FNN) is presented in this paper. This scheme uses only local output information for feedback. FNN employs orthogonal complex Fourier exponentials as its activation functions and the physical meaning of its hidden-layer neurons is clear. The FNN-based learning controller introduced here relies on the frequency-domain method, which converts the tracking problem in the time domain into a number of regulation problems in the frequency domain. A novel phase compensation method is introduced to deal with the phase lag phenomenon, so that the bandwidth of the closed-loop system is increased. Experiments on a belt-driven positioning table are conducted to show the effectiveness of the proposed controller. Index Terms--Fourier neural network (FNN), iterative learning control, orthogonal activation function, output feedback, phase compensation.

A new technique is proposed to increase the bandwidth (BW) of a Z-like slot antenna for operation at 2.4 GHz and 5 GHz, over the industrial-scientific-medical (ISM) bands and the Hiperlan2 bands. By splitting two side slots of the Z-like slot antenna into two or three fingers, several additional resonances can be created. After careful optimization of the geometrical parameters of the antenna, the resonances are merged and thus a wide impedance bandwidth is obtained. Index Terms--Double-slot, symmetrically tuning stub, triple-slot, Z-like slot.

We present a new multiresonator loaded band-rejected planar monopole antenna for ultrawideband applications. The proposed microstrip-fed antenna is composed of a flared metal plate, a truncated ground plane, and two pairs of folded strips. By applying the resonance nature of the folded strips and the associated cross coupling effects, the proposed antenna demonstrates bandstop-filter-like response with bandwidth controllability at the targeted rejection band. To illustrate the antenna operating mechanism more clearly, an equivalent circuit model consisting of RLC lumped resonators and J-inverters is discussed and extracted. The antenna input admittance calculated with the help of the equivalent circuit model agrees reasonably well with the simulated one obtained by the full-wave simulator. The design concept and the simulated and experimental results including the return losses, radiation patterns, and gain responses versus frequencies are carefully investigated throughout the paper. A parametric study in terms of the bandwidth tunability of the proposed design at the notched band is performed. The effects of the finite size ground plane are studied in this paper as well. Index Terms--Equivalent circuits, monopole antennas, resonators, ultrawideband (UWB) antennas.

Source extraction was traditionally done by sensor arrays. Recently, sensor networks have been considered as promising candidates for extraction of multiple sources. In a sensor network, each sensor observes an instantaneous linear mixture of the sources and their observations are corrupted by additive white Gaussian noise. Two sensor network models are adopted. The first one is. cluster based, in which a sensor acts as cluster head and performs local extraction of the sources based on its own observation and the received quantized data from the cluster members. Then, the extracted signal is quantized and the quantized data are sent to the sink while the sink performs global extraction of the sources. The other one is cluster free, in which data collected by the sensors are quantized and sent to the sink directly. Then, the sink performs global extraction of the sources. The proposed schemes are evaluated against the benchmarking case where the sensor observations are undistorted. Index Terms--Blind source extraction, distributed estimation, wireless sensor network.

The triple resonance network has emerged as a promising candidate for interstage bandwidth enhancement in cascaded CMOS amplifiers. This paper presents several design procedures for such networks, subject to the condition of moderate (1 dB) or no peaking in the passband, for the case where the devices can be chosen or designed, as well as the case in which the devices are given. Index Terms--Bandwidth enhancement, interstage networks, network theory, triple resonance, wide-band amplifier.

Reducing the channel change time is one of the major concerns of IPTV network deployment. This paper proposes multiple channels being delivered to household set top boxes, with a finite duration, to reduce channel change time. Unlike existing proprietary solutions that require additional equipment, or complex interactions between set top boxes and provisioning devices, the proposed method is easy to implement. We develop mathematical models to evaluate the bandwidth demand and channel change time of this method. We find that in a typical setup, the channel change time is reduced to 20%, yet the peak bandwidth increase on carrier's uplink is less than 50%. We compare the investigated method with existing ones, and argue that it is a promising alternative in terms of required bandwidth, channel change time and implementation complexity. Index Terms--Bandwidth demand, broadband access, channel change time, channel zapping, IPTV.

An enhanced microstrip antenna is proposed that incorporates a patch that rotates around the inner conductor of the coaxial line or dielectric shaft and a novel coaxial line feeding technique that offers constant electromagnetic coupling. This proposal addresses the disadvantages in our previous patch antenna in which the resonant frequency diverges from the center frequency of the personal handy-phone system (PHS) band and the bandwidth decreases as the patch rotates because of the changing electromagnetic coupling between the patch and microstrip line due to the patch rotation. We verify that this enhanced patch antenna achieves the antenna gain of approximately 0 dBd, which is the same as that of the previously proposed antenna, while suffering no significant gain degradation due to unit inclination over inclination angles from [+ or -] 45[degrees] compared to a conventional quarter-wavelength whip antenna, which experiences a degradation of approximately 2.7 dB. We show that the maximum resonant frequency separation from the center frequency of the PHS band is reduced to 15 MHz from 31.4 MHz of the previous antenna using the novel coaxial line feeding technique. The effective bandwidth needed for PHS is achieved over the inclination angles of -20[degrees] to +40[degrees]. Approximately 93% of the total bandwidth needed for PHS is achieved while the previous microstrip line type achieved only 58% coverage; accordingly, an adequate bandwidth for PHS use is obtained. Index Terms--Electromagnetically coupled microstrip antenna, new coaxial line feeding technique, personal handy-phone system (PHS), rotatable patch antenna.

In this paper, we leverage network coding (NC) to reduce the bandwidth consumption for data broadcast (DB). We use the concept of mixing in a different way from the traditional NC. Traditional NC mixes all data items together. However, we mix each data item from only some data items according to the queried and stored data of receivers. Therefore, each receiver in our approach is required to receive fewer coded data to decode the required information, and the sender, thereby, is able to broadcast fewer data items. We formulate an optimization problem with integer-linear programming to minimize the bandwidth consumption in DB. We prove that the problem is NP-hard and design an approximation algorithm that can be implemented in the data server. In addition, we show that different mixings of data items lead to different decoding costs for receivers. We design an algorithm to optimally code the data items with the minimum decoding cost. Index Terms--Data broadcast, network coding.

The aim of this paper is to study the impact of channel state information on the design of cooperative transmission protocols. This is motivated by the fact that the performance gain achieved by cooperative diversity comes at the price of the extra bandwidth resource consumption. Several opportunistic relaying strategies are developed to fully utilize the different types of a priori channel information. The analytical and numerical results demonstrate that the use of such a priori information increases the spectral efficiency of cooperative diversity, especially at low signal-to-noise ratio. Index Terms--Cooperative diversity, opportunistic relay selection, outage probability.

Time interleaving is one of the most efficient techniques employed in the design of high-speed sampled-data systems. However, the mismatches appearing among different channels will create distortion tones that will degrade the system performance. This paper presents a detailed analysis of the effect of sampling bandwidth mismatches in the statistical behavior of time-interleaved sampling systems. Closed-form and handy signal-to-noise distortion ratio formulas will also be derived which allow quick evaluation of the system performance, and the MATLAB simulations are provided in order to verify the effectiveness of those formulas. Finally, the corresponding design procedure extracted from the formulas will be further addressed through a design example. Index Terms--Bandwidth mismatches, sampled-data systems, time-interleaved (TI) analog-to-digital converter (ADC).

A partially-corporate feed is introduced to realize antennas with a larger bandwidth, by reducing the long line effect associated with the long feed waveguide. In this paper, a four-way divider is proposed to satisfy all the design requirements such as desired ratio of power division, proper phase transmission to the output ports and sufficient suppression of reflection. To confirm the band-widening effect of the partially-corporate feed structure, two 32 by 8 element array antennas with conventional series feed and partially-corporate feed are fabricated for comparison. Measurement results show that the partially-corporate feed reduces the long line effect to a half, and broadens the bandwidth of directivity to 1.5 times of the conventional series feed. Index Terms--Alternating-phase feed, corporate feed, dividers, single-layer, slotted waveguide arrays.

We show that by introducing a gap at the center of the helical sections (where the current is minimum) of a [lambda]/2 quadrifilar helix antenna (QHA) and varying the axial length and radial gap between the overlapping volutes, the antenna gives a 28% impedance bandwidth which is nine times the bandwidth of a conventional QHA. A 16% bandwidth with a front to back ratio of > 14 dB is achievable with 5-14% reduction in the size of the QHA. The structure can yield a monopole radiation pattern suitable for terrestrial applications or a hemispherical pattern suitable for satellite use. The simulation results are validated by measurements at L-band. Index Terms--Dual mode antenna, quadrifilar helix antenna, satellite antenna, size reduction, tunable antenna, wideband antenna.

A wideband single chip inductor-loaded coplanar waveguide (CPW)-fed inductive slot antenna is proposed and experimentally studied in this paper. In order to have bandwidth broadened and dimensions controlled as well, an inductor with optimal value is shunt at one far end of the inductive slot antenna to help excite an additional lower resonance point. Moreover, the bandwidth is further widened by enlarging the over-the-slot ground height. With both the optimal chip inductor and ground height values, a 10 dB return loss bandwidth of (34.5%, 1756 MHz) centered at 5083 MHz is achieved, which is, in percentage, 3.7 times the (9.3%, 531 MHz) bandwidth of the 5666 MHz stand-alone CPW-fed inductive slot antenna. Index Terms--Antenna, coplanar waveguide (CPW)-fed, inductive slot antenna, inductor-loaded, wideband operation.

Robotic exploration is an excellent method for obtaining information about sites too dangerous for people to explore. The operator's understanding of the environment depends on the rover returning useful information. Robotic mission bandwidth is frequently constrained, limiting the amount of information the rover can return. This paper explores the tradeoff between information and bandwidth based on two years of observations during a robotic astrobiology field study. The developed theory begins by analyzing the search task conducted by robot operators. This analysis leads to an information optimization model. Important parameters in the model include the value associated with detecting a target, the probability of locating a target, and the bandwidth required to collect the information from the environment. Optimizing the information return between regions creates an image and provides the necessary information while reducing bandwidth. Application of the model to the analyzed field study results in an optimized image that requires 48.3% less bandwidth to collect. The model also predicts several data collection patterns that could serve as the basis of data collection templates for improving mission effectiveness. The developed optimization model reduces the bandwidth necessary to collect information, thus aiding missions in collecting more information from the environment. Index Terms--Human computer interaction, images, robot, search.

A novel method for the design of broadband patch antennas is described. The approach taken is to broadside couple two dual-mode patch antennas, resulting in a quad resonance antenna. The equivalent circuit of the antenna is similar to that of microwave filters, thus filter design techniques maybe employed to synthesize the antenna to obtain maximum return-loss bandwidth. This is the first time an increase in the bandwidth is achieved on a relatively thin substrate antenna as a result of coupling four resonant modes using two stacked circular microstrip patches. Electromagnetic simulation and measured results demonstrate bandwidth improvement of over four times that of a single-mode design. Index Terms--Microstrip antennas, microstrip filters, microwave filters, multifrequency antenna, resonators.

Three-dimensional animating meshes have been widely used in the computer graphics and video game industries. Reducing the animating mesh complexity is a common way of overcoming the rendering limitation or network bandwidth. Thus, we present a compact representation for animating meshes based on novel key-frames extraction and animating mesh simplification approaches. In contrast to the general simplification and key-frames extraction approaches which are driven by geometry metrics, the proposed methods are based on a deformation analysis of animating mesh to preserve both the geometric features and motion characteristics. These two approaches can produce a very compact animation representation in spatial and temporal domains, and therefore they can be beneficial in many applications such as progressive animation transmission and animation segmentation and transferring. Index Terms--Animating meshes, deformation analysis, key-frame extraction, simplification.

Low-density parity-check (LDPC) codes are playing more and more important role in digital broadcasting standards due to their excellent error correction performance. In this paper, we study the combination of LDPC codes over GF(q) with q-ary modulations for bandwidth efficient transmission over AWGN channel and consider the design of the codes. Specifically, we develop the concept of quasi-regular codes, and propose an improved Monte Carlo method to optimize the quasi-regular codes. To justify the performance of our proposed scheme, simulation results are presented and analysed. Index Terms--Bandwidth efficient transmission, LDPC codes, Monte Carlo method, q-ary modulations.

The Long Range Fading Prediction algorithm for Slow Frequency Hopping (SFH) systems is proposed and demonstrated to enable combined Adaptive Modulation and adaptive Frequency Diversity to mitigate the effects of fading and partial-band interference. Significant performance gains are demonstrated relative to non-adaptive methods in realistic mobile radio SFH channels where the total bandwidth does not exceed approximately 15 times the coherence bandwidth. Index Terms--Slow frequency hopping, channel state information, long range prediction, adaptive transmission, partial-band interference, diversity.

This brief presents a new quadrature phase-shift keying (QPSK) modulator for Bluetooth applications with an optimal transaction bandwidth control. The modulator reduces the bandwidth of the modulated carrier by minimizing their transition sharpness. CMOS active transformers are developed and utilized in quadrature oscillator and multiplexer of the modulator to provide comparable phase noise performance without using spiral inductors and transformers. The performance of the modulator is assessed using a 1.6-GHz QPSK base-band modulator implemented in TSMC 0.18-[micro]m 1.8-V CMOS technology and analyzed using SpectreRF from Cadence Design Systems with BSIM3v3 device models. The total transistor area and power consumption of the modulator are 2840 [micro][m.sup.2] and 30 mW, respectively. The phase noise of the quadrature oscillator is--110 dBc/Hz at 500-kHz frequency offset.

In video applications, the storage requirement is considerably large and hence they require large amount of network resources for their transmission. For transmitting the videos through a physical channel, there are two types of channelization--constant bandwidth and variable bandwidth channelization. It has been reported that using variable bandwidth channelization the buffer storage requirement is less than that of constant bandwidth channelization. Therefore, using variable bandwidth channelization a stochastic model is proposed for estimating the buffer storage so that the continuous delivery of the video data can be provided to the users. Index Terms--Jitter delay, uniform distribution, video channelization.

In this paper, a novel cognitive multiple-access strategy in the presence of a cooperating relay is proposed. Exploiting an important phenomenon in wireless networks, source burstiness, the cognitive relay utilizes the periods of silence of the terminals to enable cooperation. Therefore, no extra channel resources are allocated for cooperation and the system encounters no bandwidth losses. Two protocols are developed to implement the proposed multiple-access strategy. The maximum stable throughput region and the delay performance of the proposed protocols are characterized. The results reveal that the proposed protocols provide significant performance gains over conventional relaying strategies such as selection and incremental relaying, specially at high spectral efficiency regimes. The rationale is that the lossless bandwidth property of the proposed protocols results in a graceful degradation in the maximum stable throughput with increasing the required rate of communication. On the other hand, conventional relaying strategies suffer from catastrophic performance degradation because of their inherent bandwidth inefficiency that results from allocating specific channel resources for cooperation at the relay. The analysis reveals that the throughput region of the proposed strategy is a subset of its maximum stable throughput region, which is different from random access, where both regions are conjectured to be identical. Index Terms--Cooperative communications, delay analysis, diversity techniques, multiple access, queueing theory, relay channel, stability analysis, stability region.

To ensure the current sharing among the interleaved phases, the peak-current control is widely used in the voltage regulator (VR) applications. Meanwhile, to save the cost and footprint by reducing the output capacitance, high control bandwidths are mandatory. Because of the sample-hold effect in the peak-current loop, there exist stringent challenges to the high-bandwidth designs for VRs. In this paper, the influence from the sample-hold effect is investigated to clarify the difference between the VR and conventional applications. After that, two approaches for higher bandwidth are introduced. To decrease the phase delay due to the sample-hold related double poles, excessive external ramps are inserted to the modulators. To increase the effective sampling frequency, the phase inductor currents are coupled, either by the coupled-inductor structure or through the feedback control. In addition, a small-signal model including the sample-hold effect is derived for the coupled-inductor buck to explain the improvement. High-bandwidth designs are verified by the simulation and experimental results. A bandwidth of one-third switching frequency is demonstrated with a coupled-inductor VR. Index Terms--Coupled inductors, high bandwidth, multiphase buck, peak-current control, voltage regulators (VRs).