Search

This document is an editorial published in Frontiers in Marine Science on the topic of maritime broadband communications and networking. The editorial highlights the importance of digitalization in the maritime industry and the need for new broadband communication technology to support various maritime activities. The document also mentions six published papers that cover different aspects of maritime networking and broadband communications, including topics such as maritime radio channel measurement and modeling, collision avoidance, and satellite systems. The authors conclude that further research in this area is needed to advance maritime broadband communications and networking. [Extracted from the article]

This paper presents the design and development of planar triplexer slot antenna using substrate integrated waveguide (SIW) technology. The proposed antenna is realised using 'Y' shaped slot backed by SIW cavity. SIW cavity is excited by three separate feed lines for resonance at three different frequencies of 5.7 GHz, 6 GHz and 6.4 GHz with unidirectional radiation pattern and gain of 6.26 dBi, 5.87 dBi and 5.19 dBi, respectively. Average isolation of the three ports is better than 24 dB. All the simulations are carried out using high frequency structure simulation (HFSS) software. The proposed antenna is fabricated on RT Duroid 5880substrate and measured results show better performance. The developed antenna is small in size (0.79 λ × 0.78 λ), simple to fabricate and easy to integrate with planar technology making it suitable for C-band application. [ABSTRACT FROM AUTHOR]

With the rapid development of broadband wireless technology and the wide demand of multimedia mobile services, various broadband mobile multimedia services are coming into being. However, the limited radio resources do not adequately guarantee the quality of service requirements for these multimedia mobile services. In this paper, the improved chaotic neural network technology is applied to three typical broadband wireless communication systems. Through the theoretical analysis and the simulation, the proposed algorithm can make full use of the chaotic neural power to search the optimal solution, which can achieve the purpose of further optimizing the wireless resources. At the same time, it also make the positive attempt to promote cross-disciplinary integration. [ABSTRACT FROM AUTHOR]

Two rectangular 1/3-octave passbands were derived from different spectral regions of everyday sentences, with the intelligibility of one band approximately twice the others. Both passbands were then filtered to produce a series of narrower rectangular passbands. Each of the original 1/3-octave passbands in turn served as the fixed bandwidth 'pedestal' and was paired with each of the series of narrower passbands of the other band. Remarkably, dual band intelligibilities were the same, regardless of which band served as pedestal, so the summed bandwidths determined intelligibility: The summed intelligibilities were irrelevant. Implications of this paradoxical 'summed bandwidth rule' are discussed. [ABSTRACT FROM AUTHOR]

Global Satellite Navigation System (GNSS) is applied widely in many fields nowadays, but is still quite limited under complex signal environments, especially weak signal situation. And the major limitation comes from the signal tracking algorithm in GNSS receiver. To solve this problem, this paper mainly deals with performance enhancement for traditional tracking framework. By inviting definition of digital equivalent bandwidth and analyzing sensitivity and stability, this framework is deeply discussed, and the relationship between correlation time and loop bandwidth setting becomes clearer. Based on this foundation, an adaptive tracking algorithm is proposed with longer correlation time under vibrated signal attenuation situation, via statistical learning of carrier phase discriminator outputs. Experiments demonstrate that our proposed algorithm outweighs the traditional one with more gain of sensitivity and stable adaptation under attenuated data situation. [ABSTRACT FROM AUTHOR]

A small broadband and low cost switched-beam smart antenna suitable for mobile WiMAX applications (band class 5-3.5 GHz) is presented in this paper. Present mobile terminal antennas are expected to show increased bandwidth as well as low-loss impedance matching while maintaining low-profile geometry. The proposed structure consists of four planar inverted-F antennas (PIFA) connected forming a cross, sharing the same ground plane, in a configuration designed for symmetrical coverage of the horizontal plane (Cross-PIFA). A custom genetic algorithm (GA) is used in order to optimize the proposed antenna parameters regarding resonant frequency and radiation pattern orientation angle and beamwidth. The optimized antenna exhibits small size (dimensions cm), satisfactory directivity for mobile terminal applications of 3.38 dB over an operation bandwidth of 120 MHz around the central frequency of 3.5 GHz. Simulation and measurement results and parameters range are exposed below followed by the according radiation pattern and variation of the VSWR indicating consistency between design and implementation. [ABSTRACT FROM AUTHOR]

The design of a tri-band dual-polarization (TBDP) shared-aperture microstrip array antenna for synthetic aperture radar (SAR) applications is presented. It operates at L-, S- and X-bands with a frequency ratio of 1:2.8:8. This TBDP shared-aperture array is assembled by two L/S and L/X DBDP shared-aperture sub-arrays with one L-band dual-polarized sub-array. A prototype array has been fabricated and measured, which exhibits wide impedance bandwidth (VSWR \leq 2) of 13.4%, 14.8%, and 16.8% in L-, S-, and X-bands, respectively. The measured array isolation is better than 37 dB in all three bands. The measured radiation patterns agree well with the simulation, confirming the cross-polarization level of below -27 dB within the main lobe region, and the array scanning capability of \pm27^\circ in S- and X-bands. This array design approach can be further extended to shared-aperture arrays with more than three bands. [ABSTRACT FROM PUBLISHER]

In this paper analysis of multilayer patch antenna has been carriedout. The antenna shows the broad bandwidth when a patch is stacked over fed patch in gap coupled structure. Typically a 42.65% bandwidth is achieved in three layer antenna. Further the bandwidth of the antenna depends inversely on the gap(s). The gain of the antenna is found to be 6.08 dB with 3 dB beam width of 92°. The theoretical results are compared with IE3D simulation and reported experimental data. [ABSTRACT FROM AUTHOR]

A novel dual-mode double square loop resonator (DMD-SLR) for dual-band band-pass filter (BPF) is presented in this paper. The simple meander loop in DMDSLR is studied to improve the performance of the conventional DMDSLR. Significant size reductions over 33% are achieved. In addition, the designed meander-loop DMDSLR filter shows lower insertion loss (2.24 and 2.28 dB), higher rejection level (28/56 dB and 53/36 dB), wider bandwidth (about 8.5% and 28%) at the 2.47 and 5.47 GHz bands, respectively. Two transmission zeros are placed between the two pass-bands and result in a good isolation. [ABSTRACT FROM AUTHOR]

A compact double-balanced monolithic star mixer for Ka-band applications using 0.25 µm GaAs pHEMT process is presented. With multi-coupled lines technology, the proposed dual 180 ° hybrid is produced and applied to a star mixer successfully. The proposed hybrid adopts the power divider and two types of multi-coupled lines to improve the return loss and isolation at the balance outputs of a traditional dual Marchand balun. Output ports are allowed to locate arbitrarily, eliminating a complex layout while the dual 180 ° hybrid is applied to double balanced star mixers. As the measurement results show, the proposed mixer achieves an operation bandwidth of 27 to 36 GHz with the best conversion loss of 6.3 dB at 28 GHz. In addition, the chip dimension can be manufactured as small as 0.81 mm². [ABSTRACT FROM AUTHOR]

Periodic broadcasting (PB) is a scalable technique for providing video-on-demand services. It significantly reduces server input and output (I/O) and backbone network bandwidth requirements, but increases the clients' need for storage space and network bandwidth. Traditional protocols assume homogeneous clients with identical resources. In practice, however, clients have very different bandwidths, which are usually not sufficient for video-on-demand service from a PB server. Existing work on heterogeneous clients has focused on devising broadcast schedules that cater to low-bandwidth clients; these schedules inevitably require additional backbone network bandwidth between the server and the clients. In this paper, we propose a scheme to significantly reduce the waiting time of all heterogeneous clients, without the need for any additional backbone bandwidth. This scheme uses a proxy buffer within video-on-demand systems using PB. In the proposed system, the server broadcasts a video using one of the traditional PB protocols. Simultaneously, the proxy receives the stream from the server and stores it in its local buffer, then broadcasts the stored data to the clients in its local network. Because the proxy provides extra, transparent channels to the server, clients are likely to reduce their reception bandwidth requirements through the use of efficient reception schedules using the extra channels. [ABSTRACT FROM AUTHOR]

Achieving fast and precise failure localization has long been a highly desired feature in all-optical mesh networks. Monitoring trail (m-trail) has been proposed as the most general monitoring structure for achieving unambiguous failure localization (UFL) of any single link failure while effectively reducing the amount of alarm signals flooding the networks. However, it is critical to come up with a fast and intelligent m-trail design approach for minimizing the number of m-trails and the total bandwidth consumed, which ubiquitously determines the length of the alarm code and bandwidth overhead for the m-trail deployment, respectively. In this paper, the m-trail design problem is investigated. To gain a deeper understanding of the problem, we first conduct a bound analysis on the minimum length of alarm code of each link required for UFL on the most sparse (i.e., ring) and dense (i.e., fully meshed) topologies. Then, a novel algorithm based on random code assignment (RCA) and random code swapping (RCS) is developed for solving the m-trail design problem. The algorithm is verified by comparison to an integer linear program (ILP) approach, and the results demonstrate its superiority in minimizing the fault management cost and bandwidth consumption while achieving significant reduction in computation time. To investigate the impact of topology diversity, extensive simulation is conducted on thousands of random network topologies with systematically increased network density. [ABSTRACT FROM PUBLISHER]

In limited feedback Transmit Beamforming for MISO systems, the most goals is to respect the constraints of the resources of the feedback channel (bandwidth and power). In the prior work systems, each user quantizes her channel state information (CSI) and fed back the corresponding number of bits to the base station every channel coherence time. Then, for a large number of users and a fixed number of feedback bits per user, the total number of feedback bits is large and the goal is not respected. In this paper, we show that the preference is to fix the total number of feedback bits. Accordingly, the number of users and the number of the feedback per user will be variable. And the number of active users is selected arbitrary from a large number of users. To analyze and validate the performance of this proposed idea, we are applying it to some techniques of transmitting Beamforming such as "the opportunistic Beamformnig (OBF)" and "the switched Sub Codebook (SSC)". Moreover, we study these two techniques with introducing the Schmidt algorithm (SA) to control the generated weights. [ABSTRACT FROM AUTHOR]

In today's digital communication world, digital video communication can be found in many applications such as broadcast services over satellite and terrestrial channels, digital video storage, wire and wireless conversational services, etc. The quantity of data for handling the visual information is very large and needs very high memory for storage and large bandwidth of the transmission channel, so it is not practical to store and transmit the full digital video without processing. For instance, for handling a 720 x 480 pixel quantity of data per frame, having 30 frames/s, with a total of 90 min full color video, the data required is about 167.96 GB. Several video compression algorithms have been developed to reduce the data quantity and provide acceptable quality. This paper explains the basic concepts of video compression techniques. [ABSTRACT FROM AUTHOR]

The combination of digital media, personal computing, and global networking is creating a radical shift in the telecom industry. However, the transport backbone, which was built on 10G wavelengths, is nearing capacity and is driving the need for upgrades to 40G and 100G. 100G Ethernet and OTU4 bring new fundamental concepts, which require new training and new testing. 100G Ethernet and OTU4 equipment is currently in development or in trial, and the next phase is to deploy this equipment in the field. This article is mostly based on the work done by IEEE P802.3ba and ITU-T Study Group 15 to provide an overview of how 100G Ethernet and OTU4 are different from previous technologies, and includes guidance on which tests need to be performed with these emerging technologies. 112G line side testing is also briefly discussed. [ABSTRACT FROM AUTHOR]

In 2006, Hao and Zielinski proposed a two-round anonymous veto protocol (called AV-net), which provided exceptional efficiency compared to related techniques. In this study, the authors add a self-tallying function to the AV-net, making it a general-purpose voting protocol. The new protocol works in the same setting as the AV-net – it requires no trusted third parties or private channels, and participants execute the protocol by sending two-round public messages. Compared with related voting protocols in past work, this is significantly more efficient in terms of the number of rounds, computational cost and bandwidth usage. [ABSTRACT FROM AUTHOR]

We propose and experimentally demonstrate a service-aware optical transport system. The proposed service-aware optical transport system makes a flow based on service type and priority of traffic. The generated flow is mapped to a corresponding sub-? for transport over an optical network. Using sub-λ provided by the centralized control plane, we could effectively provide quality-ofservice guaranteed Ethernet service and best-effort service simultaneously in a single link. The committed information rate (CIR) traffic and best-effort traffic are assigned to different sub-λs. The bandwidth of the CIR traffic is guaranteed without being affected by violation traffic because the bandwidth is managed per each sub-λ. The failure detection time and restoration time from a link failure is measured to be about 60 μs and 22 ms, respectively, in the ring network. The measured restoration time is much smaller than the 50 ms industry requirement for real-time services. The fast restoration time allows the proposed service-aware optical transport system to offer high availability and reliability which is a requirement for transport networks. [ABSTRACT FROM AUTHOR]

Minimizing the number of bandwidth changes of individual stream and enabling the transmission schedule flexible can benefit increasing the number of concurrent multiplexed streams in periodic network without degrading quality of video. However, minimum change bandwidth allocation (MCBA) only provides a fixed transmission schedule for given video and client buffer although it achieves the minimum number of rate changes and the minimum peak rate. So the MCBA schedule cannot be adjusted when multiple streams are multiplexed over a limited bandwidth shared link. In this paper, we propose a relaxing transmission schedule that provides a range of rates for each interval and preserves the minimum number of rate changes without increasing any rate. As a result, the individual schedule can be adjusted by network service to try to satisfy bandwidth constraint when the total required bandwidth of multiplexed streams exceeds the available network capacity. First, we underline that the key of MCBA is to segment video with making each linear trajectory as long as possible. Then we use linear separability and support vector machine under the classification model to compute the longest interval and the required rate, respectively. Due to our proposed decoupled form between segmentation and rate computation, finally, we construct the relaxing schedule bounded by the original MCBA rate and the minimum rate. The simulation using real MPEG4 and H.264 video traces confirms the philosophy and evaluates the relaxing performance of our proposed algorithm. [ABSTRACT FROM AUTHOR]

We analysed stability and predictive capabilities of known nitrogen absorption features between plant material prepared for NIRS (dried) and RS (fresh) studies. Grass spectra were taken of the plant canopy, and again after the grass sample was dried and ground. Models were derived using stepwise multiple linear regression (sMLR). Regression values (adj.r2) produced using the dried material were greater than those produced using canopy material. For dried material only wavebands from the SWIR region were selected. Wavebands selected by sMLR on canopy material were located in both the VNIR and SWIR regions. Using wavebands selected for dried material models produced low adj.r2 values when applied to canopy plant material; differences in adj.r2 values are smaller when wavebands selected in canopy material models are applied to dried material. Widening of nitrogen features produced higher adj.r2 values for both dried and canopy material. This work shows that obtaining models with high predictive capabilities for nitrogen concentration is possible, but waveband selection should not be limited to features identified by NIRS studies. To accommodate for variability in absorption features, and instrument errors, absorption features should be widened. [ABSTRACT FROM AUTHOR]

This paper proposes the semaphore authority management (SAM) controller to optimize the dual-port SDRAM (DPSDRAM) in the mobile multimedia systems. Recently, the DPSDRAM with a shared bank enabling the exchange of data between two processors at high speed has been developed for mobile multimedia systems based on dual-processors. However, the latency of DPSDRAM caused by the semaphore for preventing the access contention at the shared bank slows down the data transfer rate and reduces the memory bandwidth. The methodology of SAM increases the data transfer rate by minimizing the semaphore latency. The SAM prevents the latency of reading the semaphore register of DPSDRAM, and reduces the latency of waiting for the authority of the shared bank to be changed. It also reduces the number of authority requests and the number of times authority changes. The experimental results using a 1 Gb DPSDRAM (OneDRAM) with the SAM controllers at 66 MHz show 1.6 times improvement of the data transfer rate between two processors compared with the traditional controller. In addition, the SAM shows bandwidth enhancement of up to 38% for port A and 31% for port B compared with the traditional controller. [ABSTRACT FROM AUTHOR]

A novel study of ultra wideband (UWB) communication over the indoor powerline channel, in a wide frequency range up to 1 GHz is presented. An exhaustive measurement campaign was conducted on a test bed that replicated the environment of an indoor powerline network. The aim of this study was to observe and analyse the transmission and noise properties of such a broadband powerline channel. A time domain channel model has been used to study the broadband channel response of the powerline. Measurement and modelling results show that the indoor powerline channel provides a communication link in the 50–550 MHz frequency range. Channel capacity is greatly enhanced by exploiting the 500 MHz bandwidth. The conclusions of this study indicate that gigabit per second data rate transmission are possible over the indoor powerline channel in 50–550 MHz. [ABSTRACT FROM AUTHOR]

This paper focuses on assessment and design of transmission systems for distribution of digital signals over standard Category-7A copper cables at speeds beyond 10 Gbps. The main contribution of this paper is on the technical feasibility and system design for data rates of 40 Gbps and 100 Gbps over copper. Based on capacity analysis and rate optimization algorithms, system parameters are obtained and the design implementation trade-offs are discussed. Our simulation results confirm that with the aid of a decision-feedback equalizer and powerful coding techniques, namely, TCM or LDPC code, 40 Gbps transmission is feasible over 50 m of CAT-7A copper cable. These results also indicate that 100 Gbps transmission can be achieved over 15 m cables. [ABSTRACT FROM AUTHOR]

This article presents comprehensive methods for the design of a wideband CMOS transmit/receive (T/R) switch. Techniques such as RF floated body to extend the bandwidth and decrease the insertion loss (IL), and stacking architecture with high substrate isolation to enhance the power-handling capability, are used for the design of a T/R switch on a standard 0.18-μm triple-well process. The measured performance of the T/R switch demonstrates the effectiveness of the methods presented in this article such that IL less than 1.28 dB, isolation higher than 24 dB, and input 1 dB compression point of 27 dBm can be achieved from 2 to 5.8 GHz. [ABSTRACT FROM AUTHOR]

This paper proposes a novel planar Wilkinson power divider operated in 2.4 GHz/UWB with a notch characteristic in the 5.2 GHz WLAN band (4.7–5.7 GHz) by using a simple defected ground structure (DGS). Over the whole operating band except the notched frequency band, the measured results explore broadband operation with return loss of higher than 10 dB, a low insertion loss of less than 0.8 dB and good isolation of higher than 10 dB. It shows good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

The caching of frequently accessed data items on the client side is an effective technique to improve performance in a mobile environment. Caching data in a wireless mobile computer can significantly reduce the bandwidth requirement. However, cache content needs to be validated; classical cache invalidation strategies are not suitable for mobile environments due to the disconnection frequency and mobility of the mobile clients. Attractive cache invalidation techniques are based on invalidation reports (IRs). But, IR-based cache invalidation schemes result in considerable consumption of uplink and download bandwidth. In this paper, we address these problems by presenting a new energy-efficient cache invalidation method for the wireless mobile environment. The new cache invalidation scheme is called Adaptive Energy Efficient Cache Invalidation Scheme (AEECIS). The algorithm is adaptive since it changes the data dissemination strategy based on the current conditions. To reduce the bandwidth requirement, the server transmits in one of three modes: slow, fast or super-fast. The mode is selected based on thresholds specified for time and the number of clients requesting updated objects. An efficient implementation of AEECIS is presented and simulations have been carried out to evaluate its caching effectiveness. The results demonstrate that it can substantially improve mobile caching by reducing the communication bandwidth (thus energy consumption) for query processing. Also, the reported results demonstrate that compared to previous IR-based schemes, AEECIS can significantly improve the bandwidth consumption and the number of uplink requests. [ABSTRACT FROM AUTHOR]

Shared-link AXI provides decent communication performance and requires half the cost of its crossbar counterpart. The authors analysed the performance impact of the factors in a shared-link AXI system. The factors include interface buffer size, arbitration combination and task access setting (transfer mode mapping). A hybrid data locked transfer mode was also proposed to improve the performance due to AXI's extra transition cycle. The analysis is carried out by simulating a multi-core platform with a shared-link AXI backbone running a video phone application. The performance is evaluated in terms of bandwidth utilisation, average transaction latency and system task completion time. The analysis showed that channel-independent arbitration could contribute up to 23.2% of bandwidth utilisation and completion time difference. Moreover, the analysis suggests that the proposed hybrid data locked mode should be used only by long access latency devices. Such setting resulted in up to 21.1% completion time reduction compared with the setting without the hybrid data locked mode. The design options in shared-link AXI bus are also discussed. [ABSTRACT FROM AUTHOR]

A novel ultra-wide bandwidth (UWB) channel measurement approach based on chirp pulse sounding signal in an automotive vehicle is proposed. An UWB channel impulse response (CIR) estimator using de-convolution technique is constructed to verify that the chirp pulse sounding signal generated with rectangular window is 12.71 dB better in accuracy than the Gaussian pulse sounding signal to measure the CIR of the UWB channel. The UWB channel measurement in the frequency band of 4.25–4.75 GHz is carried out inside an automotive vehicle. The experimental results validate the correctness of using chirp pulse sounding signal to measure the UWB channel inside an automotive vehicle with windows closed through the root mean square delay spread for Cases A and B radio propagation channel models of IEEE 802.15.3a UWB standard when the threshold is properly chosen. Also, test results show that opening the vehicle's window may change the channel characterisation. [ABSTRACT FROM AUTHOR]

In this paper, we analyze bit error rate performance of a special case of multitone CDMA systems that is Replica MT-CDMA system. It is shown that with the same bandwidth, the Replica MT-CDMA outperforms the conventional system that we name it S/P MT-CDMA. We also propose a low-rate bandwidth efficient channel coding scheme for Replica MT-CDMA that by using it, the coded Replica MT-CDMA system needs the same bandwidth as the uncoded one. In this paper, we compare the proposed low-rate coded and uncoded Replica MT-CDMA systems with S/P MT-CDMA system over uplink Rayleigh fading channel. Our results show that with the same bandwidth, the performance of the coded Replica MT-CDMA system with the proposed channel coding scheme is considerably better than that of both uncoded MT-CDMA systems. [ABSTRACT FROM AUTHOR]

Due to the recent popularization of digital broadcasting systems, selective contents, i.e., watching contents selected by users themselves, have attracted great attention. For example, in a news program, after a user selects an interesting content, he/she watches it. In selective contents broadcasting, since the server needs to deliver many contents, the necessary bandwidth for continuously playing the data increases. Conventional schemes reduce the necessary bandwidth by producing an effective broadcast schedule. However, they do not consider the upper limit in the bandwidth. When an upper limit exists in the bandwidth, users may wait to play the data. In this paper, we propose a broadcasting scheme that reduces waiting time by considering available bandwidth. In our proposed scheme, by acquiring the channel bandwidth that is the same as the data consumption rate, we effectively reduce the waiting time. [ABSTRACT FROM AUTHOR]

In the last few years, IPTV has emerged as one of the major distribution and access techniques for broadband multimedia services. It is one of the primary growth areas for the telecommunications industry. However, existing IPTV systems are generally based on proprietary implementations that do not provide interoperability. Recently, many international standard bodies have published, or are developing, a series of IPTV related standards.. This paper is an overview of the most significant recent and upcoming IPTV standards. [ABSTRACT FROM AUTHOR]

Impulse radio ultra wideband (IR-UWB) can achieve high resolution in ranging because it uses a very short pulse with a duration of less than 1 ns. In order to reduce cost and power consumption, a ranging system with high-speed comparators has been proposed. In this system, it is necessary to reduce noise power through averaging the comparator outputs. The authors evaluate the effect of clock offset on the averaging process, and a two-stage averaging scheme for the IR-UWB ranging system is proposed. Through computer simulation, it is proved that the proposed scheme can reduce the effect of the clock offset with appropriate numbers of initial averaging. [ABSTRACT FROM AUTHOR]

Significant research has been dedicated to active probing methods used to estimate the end-to-end available bandwidth (avail-bw) of a network path. The measurement speed of an avail-bw estimation tool is vital to real-time network services such as transport control protocol (TCP) slow start, path selection for P2P applications and video streaming services and so on. In addition, a fast avail-bw estimation tool sends less probing traffic to a measured network. Pathload, a one way delay (OWD) based tool, has been widely regarded as one of the most accurate tools, but its estimation speed is often 10 or more seconds per measurement. A fast OWD-based avail-bw estimation scheme has been explored. This scheme is based on the proposed asymptotic OWD comparison model, and an estimation tool called Pathpair has been developed. Validated in a real Internet environment, experimental results show that with Pathpair the measurement speed has been significantly improved (1–3 s per measurement), while preserving accuracy compared with other major tools like Pathload and Spruce. [ABSTRACT FROM AUTHOR]

In the tone reservation (TR) scheme of the orthogonal frequency division multiplexing (OFDM) systems, there exists a trade-off between the peak to average power ratio (PAPR) reduction performance and the peak reduction tone (PRT) set size. In this paper, we propose a multi-stage TR scheme for PAPR reduction, which adaptively selects one of several PRT sets according to the PAPR of OFDM signal while the PRT set is fixed for the conventional TR scheme. It is shown that the PAPR reduction performance of the proposed scheme is better than that of the conventional TR scheme when the tone reservation rate (TRR) is the same. [ABSTRACT FROM AUTHOR]

Usually, power filters are characterised by their insertion loss (IL). By definition, the IL is applicable to two-port networks, but most filters have a higher number of ports. Single-phase power filters are four-port networks and measurements of their suppression characteristics require one measurement for the common-mode (CM) and another for the differential-mode (DM) IL. Normally, the measurement apparatus have unbalanced ports and CM measurements are relatively easy to perform. However, the DM measurements require balanced–unbalanced conversion at the input and output of the filter. Wideband transformers (baluns) are used for this conversion. Instead of measuring it directly, the CM or DM IL can be calculated from the four-port parameters of the filter. The equations for IL in terms of four-port network parameters are derived theoretically and verified experimentally. The adoption of four-port parameters in engineering practice would reduce the amount of measurement work and increase the reliability and repeatability of the results because the use of baluns or other changes in the equipment under test are not necessary. [ABSTRACT FROM AUTHOR]

In this paper, we extend the results of our previous work, which mainly focuses on homogeneous services, and discuss the heterogeneous scenario. A cross-layer design is proposed for IEEE 802.16/WiMAX networks, in which three modules are added: 1) an M-gated scheduler; 2) an admission controller; and 3) a parameter controller. The parameter setting for the M-gated scheduler is based on performance analysis and different services' features, whereas the admission controller policy is deployed on the theoretical results. Using the probability-generating function, a queuing model is developed for the system under the proposed cross-layer design. In the queuing model, the "wireless" feature that the capacity of the channel randomly varies with time is considered. Simulations validate the theoretical results and demonstrate the performance of the proposed cross-layer scheme. For real-time services, the proposed scheme can achieve the goal of users' quality-of-service (QoS) demand in most cases and saves more surplus bandwidth for the best effort (BE) service. For BE, the proposed scheme can make a good tradeoff between bandwidth utilization and the left bandwidth for BE. [ABSTRACT FROM AUTHOR]