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Optimizing downlink coordinated multipoint (CoMP) performance through advanced scheduling algorithms enhances V2X communication technology, enabling efficient resource allocation, minimizing interference, and maximizing data rates for reliable and synchronized communication between vehicles and infrastructure. In this paper, several scheduling algorithms were compared, including support vector machine (SVM) linear, SVM Radial Basis Function (RBF), SVM Sigmoid, Deep Neural Networks (DNN), Convolutional Neural Networks (CNN), and Graph Convolutional Networks (GCN). The performance metrics used in this comparison included CoMP decision, throughput, and cell edge throughput. The results showed that the out-rated GCN algorithm had the best-triggering composition for 5G radio networks, outperforming the other algorithms in terms of CoMP decision accuracy and overall throughput. In particular, the GCN algorithm demonstrated significant improvements in cell edge throughput, which is critical for ensuring reliable communication in areas with weaker signal strength. The reported results proves that the integration of advanced scheduling algorithms in the downlink CoMP framework enhances the efficiency of V2X communication, enabling optimized resource allocation, interference mitigation, and maximized throughput, thereby improving system efficiency, reducing latency, and ensuring reliable and seamless information exchange for connected vehicles, smart cities, and industrial automation. [ABSTRACT FROM AUTHOR]

The Narrowband Internet of Things (NB-IoT) has been introduced in the 3rd Generation Partnership Project (3GPP) Rel-13 with the aim to provide low-cost, low-power, wide-area cellular connectivity for the Internet of Things. With the exponentially increasing number of connected wireless devices in the order of 100 billion, it has become crucial that researchers develop efficient resource management techniques to meet the 5th Generation (5G) quality of service (QoS) requirements. Recently, several research challenges including the low modulation data rates, energy-expensive channel coding techniques, and the fast-growing number of connected devices have been identified as some of the main issues encountered in the design and deployment of NB-IoT systems. In addition, several techniques have emerged in the literature to resolve some of these challenges of NB-IoT systems. However, the research activities towards the enhancement of the NB-IoT resource management are yet to continue in the next half-decade before, high data rates, energy-efficient, and scalable NB-IoT specifications can be released for the standardisation and commercialisation. Considering the limited number of existing surveys of such technical enhancement approaches in a broader perspective (i.e. energy efficiency, data rate performance and scalability) and also the non-existence, to the best of our knowledge, of a comparative survey, this paper seeks to elaborate, describe and compare the performances of such resources management approaches. Of the multiple NB-IoT resources, the focus of this paper is on the data rate, energy efficiency, and scalability enhancement schemes that have been proposed for the last three years. The contribution of the paper lies in the analysis, synthesis, comparison and summarised alignments of some of the major existing schemes towards identifying challenges faced by the NB-IoT development. Finally, this work seeks to identify research challenges, open questions, and opportunities that could arise from the existing techniques analysed.

In this work, it is proposed that the use of statistical percentage of errors correlated to the Received Signal Strength (RSS) and to both the output power and noise bandwidth, together with the data rate ratio, can give a clear indication of the communication channel quality in the presence of a noise floor. Simulation of a WSN network with variable Data Rate to Noise Band Width ratio (R), different output power (Ptran), and variable Noise Floor Power (Pnoise), showed that each one of these parameters affects error probability distribution and values, which in turn affect channel utilization. The work also proved that these are critical parameters that, if correlated and optimized, can achieve a high utilization of WSN channels. The largest effect realized is related to Pnoise and interference, which, if present at high values, would reduce the probability of exchanging data by 25%. The work also showed that as the ratio R increases, the probability and magnitude of errors increases, which in turn contributes to lower utilization, as depicted in the tables and plots. The 10-nodes WSN is simulated in a uniform topology setting. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) is a promising technique to provide connectivity to users while providing illumination. To further improve the data rates of VLC systems, multiple sources that transmit multiple simultaneous data streams can be used. This Letter proposes a novel mixture model for VLC systems that make use of multiple sources to provide sufficient flexibility to accurately model the received signal levels for enabling better system designs. The validity of the proposed model is empirically verified through a set of real‐life measurements. [ABSTRACT FROM AUTHOR]

This paper focuses on the design optimization of communication satellites for the constellation in low earth orbit (LEO). The optimization starts with defining an objective function, which is the total mass of satellites, as a function of their orbit altitude, antenna transmit diameter, and nominal data rates. The optimization routine was done in order to minimize the total mass of satellites in order to reduce the total launch mass and the total cost. The use of three different design parameters has led to a genetic algorithm (GA) as an optimization method to find the best value for each design parameter. The results show that the optimization process using a genetic algorithm is successfully applied in solving complex multidisciplinary design problems such as the design of a communication satellite system with acceptable error. [ABSTRACT FROM AUTHOR]

Most of the current research work on the Narrowband Internet of Things (NB-IoT) is focused on enhancing its network coverage. Many of the existing NB-IoT channel coding techniques are based on repeating transmission data and control signals as a way of enhancing the network’s reliability and therefore, enabling long-distance transmissions. Although most of these efforts are made at the expense of reducing the energy consumption of the NB-IoT network, they do not always consider the channel conditions. Therefore, this work proposes a novel NB-IoT Energy-Efficient Adaptive Channel Coding (EEACC) scheme. The EEACC approach is a two-dimensional (2D) approach which not only selects an appropriate channel coding scheme based on the estimated channel conditions (dynamically classified as bad, medium or good from initial based on a periodically assessed BLER performance outcome) but also minimizes the transmission repetition number under a pre-assessed probability of successful transmission (based on the ratio of previous successful transmissions over the total number of transmissions). This results in creating a single mixed gradient based on which a higher or lower Modulating Coding Scheme (MCS) is selected on each transmission. It is aimed at enhancing the overall energy efficiency of the network by dynamically selecting the appropriate Modulation Coding Scheme (MCS) number and efficiently minimizing the transmission repetition number. Link-level simulations are performed under different channel conditions (good, medium, or bad) considerations to assess the performance of the proposed up-link adaptation technique for NB-IoT. The obtained results demonstrate that the proposed technique outperforms the existing Narrowband Link Adaptation (NBLA) as well as the traditional repetition schemes in terms of the achieved energy efficiency as well as network reliability, latency, and scalability.

A 4:1 multiplexer (MUX) circuit in SiGe BiCMOS technology intended to directly drive a plasmonic Mach–Zehnder modulator for transmitter applications is presented. To achieve the highest data rates at a high output voltage swing, a power MUX concept is applied that maps the high‐speed performance of the final clock signal onto the output data. In the clock tree a novel wideband 90° clock phase shifter circuit is utilised for timing adjustment and frequency doubling. Electrical measurements of the chip demonstrate open eye diagrams for non‐return‐to‐zero on‐off‐keying (NRZ‐OOK) signals up to 180 Gbit/s, which is record speed for Si‐based technologies. A differential output voltage swing of 300mVpp was measured that corresponds to an output voltage swing of more than 1Vpp without the bandwidth limit of the measurement equipment. [ABSTRACT FROM AUTHOR]

InAlAs/InGaAs avalanche photodiodes (APD) were simulated using physical device models, then designed and fabricated to detect light in the wavelength range from 1.3 to 1.55 µm. DC characterisation under dark and light conditions were performed at room temperature to measure and investigate the performance of the APD. High‐frequency characterisation was carried out on the device to extract the diode intrinsic and extrinsic parameters. The work reported here focuses on the dark and light physical device simulations (both under DC and AC conditions) which were accomplished using Atlas SILVACO tool. The effect of electron velocity overshoot was considered for accurate bandwidth modelling. All measured data are in excellent agreement with the modelled ones. The internal device gain of the APD is 45 at −23.5 V leading to a ∼220 GHz gain–bandwidth product. This successful APD model can be exploited to further improve the diode structure for higher data rate applications beyond 10 Gb/s. [ABSTRACT FROM AUTHOR]

Miniaturised transceivers are essential in multiband wireless communication systems for higher data rates and low power consumption. Microelectromechanical system (MEMS) resonator filters are actively considered for deployment in transceivers for radio frequency and intermediate frequency (IF) signal filter and oscillator applications. In this study, the authors propose dual frequency capacitive transduced MEMS resonator with two‐port electrical configuration. Clamped–clamped beam resonator was selected to serve as a basic resonant tank for the filter concept validation. Five design strategies low loss structural material, array design, mixed electrical and mechanical coupling scheme, sub‐micro meter transduction gap and large transduction area were explored. With these strategies, the device achieves dual band filter characteristics, narrow pass band, desired bandwidth, low insertion loss and better stop band rejection. Dual frequency response of the proposed resonator is demonstrated at centre frequencies 400 kHz and 2.57 MHz with a narrow pass band of 3 and 20 kHz, respectively. Low insertion loss of 19.8 and 25.6 dB for frequencies centred at 400 kHz and 2.57 MHz, respectively and stop band rejection >35 dB was achieved. The proposed MEMS resonator may be incorporated in the implementation of dual band pass filter for IF signal filter and dual frequency oscillator applications. [ABSTRACT FROM AUTHOR]

The ATLAS Inner Detector will be replaced with a new all-silicon Inner Tracker (ITk) designed for the challenging environment of the High Luminosity LHC (HL-LHC). The ITk layout of the pixel detector was recently successfully optimized to improve tracking performance and object reconstruction. The data rates of the ITk pixel detector have been evaluated to establish that the detector readout system can read out data at the design L0 trigger frequency of 1 MHz. [ABSTRACT FROM AUTHOR]

In this issue’s “Antenna Applications Corner” column, author Rainee N. Simons from NASA’s Glenn Research Center describes link analysis of high-throughput satellite communication systems and its impact on the antenna design and performance for future low Earth orbit (LEO) satellites being planned by NASA. The article discusses two scenarios: 1) the first one employs a high data rate link between LEO and ground via relay satellites in geostationary orbit, and 2) the second one is a high data rate link from LEO directly to ground. Link analysis and data rates are shown for both cases, taking into account effective isotropic radiated power, waveforms, elevation angle, path losses, and the receiving antenna gain/system temperature. This article is useful for system and antenna engineers working on link analysis and hardware trades. [ABSTRACT FROM AUTHOR]

A silicon–germanium BiCMOS E‐band power amplifier (PA) for millimetre‐waves for Gbit/s data rates in fifth‐generation cellular wireless backhaul networks is presented. A 69–78 GHz transmission‐line PA is demonstrated by integrating an electrostatic discharge (ESD) and a power detector together. To save this area, a transmission‐line‐based power coupler is shared by the ESD and the power detector. The ESD achieves an insertion loss of <1.5 dB in the frequency range of 17–100 GHz. The linear‐in‐dB output characteristic of the power detector is achieved by an exponential voltage convertor. The designed PA measured a maximum gain of 18.6 dB with 3 dB bandwidth of 68.9–78.7 GHz. The input return loss is better than −10 dB from 50 to 81 GHz. It delivers 10 dBm saturated output power at 73.4 GHz. Transmission line pulsing (TLP) measurement result shows that the voltage is clamped below 6 V even under 10 A ESD current. [ABSTRACT FROM AUTHOR]

In this letter, the performance of non-orthogonal multiple access (NOMA) is investigated in a cellular downlink scenario with randomly deployed users. The developed analytical results show that NOMA can achieve superior performance in terms of ergodic sum rates; however, the outage performance of NOMA depends critically on the choices of the users' targeted data rates and allocated power. In particular, a wrong choice of the targeted data rates and allocated power can lead to a situation in which the user's outage probability is always one, i.e. the user's targeted quality of service will never be met. [ABSTRACT FROM AUTHOR]

Canonical logic units (CLUs) are basic building blocks for complex all‐optical logic operations, and multicast of CLUs can improve the computing capacity and operating flexibility. The authors thus propose and experimentally demonstrate all‐optical reconfigurable multicast two‐input CLUs (i.e. minterms) at 40 Gb/s by using four‐wave mixing in a single highly non‐linear fibre. Each type of CLUs with clear temporal waveform and wide eye opening is achieved in five parallel channels simultaneously. The extinction ratios are >10.3 dB, while the optical signal‐to‐noise ratios are >21 dB. Based on the demonstrated scheme, a method of realising simultaneous full set of two‐input logic operations is proposed and discussed. The proposed scheme can be extended to higher data rates and transferred to on‐chip platforms. [ABSTRACT FROM AUTHOR]

Multimode polymer waveguides constitute a promising technology for use in board-level optical interconnects. However, the continuous improvements in high-speed performance of VCSELs raise important questions about their ability to support such high data rates due to their inherent highly multimoded nature. Thorough experimental studies on the bandwidth of a 1.4-m-long multimode spiral waveguide are presented in this letter, indicating a bandwidth-length product of at least 35 GHz×m even in the case of an overfilled launch. No significant transmission impairments are observed for spatial input offsets, while error-free (BER <; 10-12) data transmission over the 1.4-m-long spiral waveguide is demonstrated at 25 Gb/s. [ABSTRACT FROM PUBLISHER]

A new scheme for a flexible modulation and bit rate independent, polarization-insensitive optical wavelength converter (WC) based on four-wave mixing in a highly nonlinear fiber is demonstrated and characterized for different modulation formats and data rates. Its robustness is demonstrated in a data transmission experiment in which the WC is incorporated at the mid-point of a transmission line based on installed fiber. In addition, an optical feedback system designed to prevent slow polarization drift of the pumps, and consequently, to ensure the long-term stability of the system is implemented and characterized. The WC is tested with the feedback system in place enabling turn-key operation. [ABSTRACT FROM PUBLISHER]

Abstract: To optimize performance of ad hoc networks, the contradicting objectives: energy conservation and high data rate realization need to be jointly considered. In such a case, network interference need to be controlled in a manner that users transmit at minimum power enough to sustain the transmission. This paper proposes a joint power and rate adaptation in ad hoc network based on coupled interference minimization (PRIM) where the formulated network utility maximization (NUM) is solved using reverse engineering based on Karush-Kuhn-Tucker (KKT) conditions. In that way, users determine their transmit power and data rate based on their local observations (coupled interference). Pricing mechanism is employed in PRIM to restrict users from self-interest behaviours. It is demonstrated theoretically that PRIM satisfies the conditions of the super-modular games such that the local optimality is always the global optimality. Simulation results have shown that adapting transmits power and data rates based on the coupled interference (i.e. link dynamics) can improve the performance of ad hoc networks. [Copyright &y& Elsevier]

The proliferation of high-bit-rate wireless services such as multimedia and highspeed Internet access is driving the development of next-generation wireless communication systems to support much higher data rates than the current second-generation (2G) and the emerging third-generation (3G) systems. In this article, we present a new technique for a point-to-multipoint network (such as the forward link in a cellular system), which we refer to as spread space-spectrum multiple access (SSSMA). This scheme uses all the degrees of freedom in the frequency, time, and space dimensions for the transmission of each signal. [ABSTRACT FROM PUBLISHER]

Fiber optics is proving to be an essential transmission medium at data rates of 1 Gigabit per second and above because of advantages relative to copper, including increased distance-bandwidth, reduced weight, and reduced cable volume. Whereas implementation in commercial applications is often straightforward, aerospace applications present a number of challenges due to an environment harsher than exists in the commercial world. In order to meet the future needs of military aircraft, designers will have to choose carefully between a number of component and architectural choices now available. This paper examines current trends in aerospace fiber optics and maps future needs for aerospace. [ABSTRACT FROM PUBLISHER]

The metropolitan network environment is a fast-growing and challenging space for optical communications. The environment spans a large range of length scales, channel counts, data rates, and services/formats. The large range of this application space places some unique requirements on the network elements required to implement these networks. The objective of this workshop is to better understand the requirements, design, and implementation of these network elements from both a business and technical point of view-with a special emphasis on amplifiers and active elements. Panelists will provide brief presentations followed by a question and answer session. [ABSTRACT FROM PUBLISHER]

A novel class of constant-length variable-weight optical orthogonal codes is proposed that can support multimedia services with different data rates and quality-of-service requirements. The construction is based on the pairwise balanced designs, or more specifically, on an incidence structure defined on an integer lattice. Proposed codes are suitable for spectral-amplitude coding, fast-frequency hopping, and time-spreading encoding in multimedia environment. A novel dual-balanced decoder is proposed capable of canceling multiuser interference in multimedia applications for spectral-amplitude-coding schemes employing the unipolar codes having nonfixed in-phase cross correlation. [ABSTRACT FROM PUBLISHER]

By employing more than one antenna at the transmitter and by properly coding data across the transmit antennas, physical layers (PHYs) with space-time block codes (STBCs) promise increased data rates with minimal decoding complexity at the receiver. This paper presents a comprehensive study of how the STBC gains at the PHY translate to significant network performance improvement in 802.11a wireless local area networks. We base our study on a detailed, across-all-layers, simulation of an 802.11a system. We have extended the network simulator with an implementation of the 802.11a PHY, which allows us to assess the impact of STBC not only at the PHY layer, but at the higher layers as well. An extensive set of simulations illustrates the merits of transmit diversity (in the form of STBC) and sheds light on how performance can be improved for transmission control protocol (TCP) traffic. Essentially, STBC presents to TCP a "smoother" wireless channel; this is corroborated by a brief theoretical analysis as well. [ABSTRACT FROM PUBLISHER]

Wireless local area networks have emerged as one of today's driving technologies, delivering high data rates on unlicensed spectrum. This article provides an overview of a new signaling system for high-bit-rate wireless LAN, made possible by a novel class of signaling pulses. Called OWSS pulses, they are generated through a combination of orthogonal wavelength-division multiplexing and spread-spectrum concepts. The system offers several advantages including intrinsic robustness to frequency-selective fading, effective equalization due, in part, to the wide spectrum and wide time-support of the pulses used, high data rate, and flexibility in carving different rates versus multiple access schedules at the physical layer. [ABSTRACT FROM PUBLISHER]

This article discusses an evolutionary TDD mode of CDMA-based path for 3.5G/4G systems. This technology has already been the basis of two 3G standards: TD-CDMA and TD-SCDMA with a synchronous uplink. Several techniques have been developed that allow TDD-CDMA-based systems to transmit at rates usually associated with 3.5G to 4G, up to 10-20 Mbit/s with wide area coverage. The present TDD-CDMA-based 3G standards are evolving to provide these higher rates, while fully retaining the coverage and mobility associated with, and expected from, the present mobile communications systems. This article discusses how TDD-CDMA specific techniques facilitate delivering services at data rates associated with 3.5G and 4G. We review how TDD-CDMA can provide for asymmetric uplink and downlink transmissions, facilitate deployment of advanced antennas for improved downlink coverage, and enable provision of advanced receiver techniques in base stations and mobiles. We also discuss how these techniques affect systems capacity in full packet-switched IP-based systems. We then discuss 4G TDD CDMA systems: those with different modulation techniques for uplink and downlink communications. These are generally based on a multicarrier mode of CDMA, and may incorporate OFDM technique. [ABSTRACT FROM PUBLISHER]

Multipath dispersion and fluorescent light interference are two major problems in indoor wireless infrared communications systems. Multipath dispersion introduces intersymbol interference at data rates above 10 Mb/s, while fluorescent light induces severe narrowband interference to baseband modulation schemes commonly used such as OOK and PPM. This article reviews the research into the application of direct sequence spread spectrum techniques to ameliorate these key channel impairments without having to resort to complex signal Processing techniques. The inherent properties of a spreading sequence are exploited in order to combat the ISI and narrowband interference. In addition, to reducing the impact of these impairments, the DSSS modulation schemes have strived to be bandwidth-efficient and simple to implement. Three main DSSS waveform techniques have been developed and investigated. These are sequence inverse keying, complementary sequence inverse keying, and M-ary biorthogonal keying (MBOK). The operations of the three systems are explained; their performances were evaluated through simulations and experiments for a number of system parameters, including spreading sequence type and length. By comparison with OOK, our results show that SIK, CSIK, and MBOK are effective against multipath dispersion and fluorescent light interference because the penalties incurred on the DSSS schemes are between 0-7 dB, while the penalty on OOK in the same environment is more than 17 dB. The DSSS solution for IR wireless transmission demonstrates that a transmission waveform can be designed to remove the key channel impairments in a wireless IR system. [ABSTRACT FROM PUBLISHER]

Ambient light is the main impairment in indoor wireless optical communication systems for data rates up to several megabits per second. Its wide dynamic range, associated with the strong directivity of wireless optical signals, produce large variations on the received signal-to-noise ratio. This article discusses experimental results obtained from a testbed developed to compare different techniques for SNR improvement. The two techniques analyzed are rate-adaptive transmission, which introduces adaptive levels of redundancy in the transmitted signal to improve connectivity, and angle diversity reception, which exploits the inherent directionality of both signal and noise to improve the SNR at the receiver. Furthermore, systems employing both techniques simultaneously were also considered. The testbed replicated a typical indoor environment with both natural and artificial light, containing incandescent and fluorescent light sources. Both the SNR and the associated coverage areas were determined for all considered techniques. Our results show that the combined use of angle diversity based on maximal ratio combining and rate adaptation through the use of repetition coding achieves very good performance with only moderate complexity, allowing connectivity at all locations with data rates close to the maximum possible. In particular, with incandescent illumination and without angle diversity, the data rate had to be decreased down to 2 and 1 Mb/s in 25.9 and 7.7 percent of the room, area, respectively, whereas with maximal ratio combining a decrease to 2 Mb/s was only needed in 0.7 percent of the room area. [ABSTRACT FROM PUBLISHER]

An architecture demonstrator of an innovative interconnect scheme called the optical centralized shared-bus is presented. This architecture retains the advantages of shared-bus topology while at the same time specifying a uniform interface between the electrical and the optical backplane layers in contrast to other proposed architectures. For the first time, a fanout equalized optical backplane bus is demonstrated. In this architecture demonstrator, the data paths required for the microprocessor-to-memory interconnects are provided by the optical centralized shared-bus. The optoelectronic interface modules are optimized to support data rates up to 1.25 Gb/s. The objective of this microprocessor-to-memory interconnects demonstration is to ensure the feasibility of applying this innovative architecture in real systems. [ABSTRACT FROM PUBLISHER]

The problem of jointly controlling the data rates and transmit powers of users, so as to maximize throughput in cellular direct-sequence code-division multiple-access (CDMA) networks is addressed. The multicode (MC)-CDMA system, where the processing gain of each code is fixed and high-rate users use multiple codes for transmission, and the variable gain (VG)-CDMA architectures are considered. The throughout maximization problem is formulated as a classical optimization problem, modeling the constraints arising from the data rate requirements and power budgets. Optimal strategies to maximize throughput in both systems are derived. While the MC-CDMA system has a simple optimal rate-power allocation algorithm, the VG-CDMA system has a more complex solution. [ABSTRACT FROM PUBLISHER]

A major problem for TCP connections over wireless links is that errors introduced by the wireless channel interfere with the TCP protocol, leading to reduced data rates and power wastage. Based on accurate simulations for the TCP and IEEE 802.11 MAC protocols, we discuss recipes to optimize transmission. It is argued that the best approach is to restrict modifications to the mobile device. While this requires separate solutions for the uplink and downlink, the results of optimization are then available when roaming into any WLAN obeying the relevant MAC protocol. Simulation results show that the combination of specific strategies with a vertical interaction between the protocol layers can lead to the required improvements, giving a promising approach to enhance the performance of wireless mobile terminals. [ABSTRACT FROM PUBLISHER]

The need for wireless communication systems has grown rapidly during the last few years. Moreover, there is a steady growth in the required data rates due to the fact that more and more users request high-bit-rate services. To meet those requirements, current and next-generation wireless systems and networks such as wireless LANs (e.g., IEEE 802.11a) will support much higher data rates compared with established standards. This is basically done by applying advanced transmission schemes and usage of bandwidth resources. Another very promising approach is the introduction of multiple antennas at one or both ends of a link to exploit the spatial dimension of signal transmission for improved link quality and enhanced system capacity. Smart antenna concepts are extensively discussed in this context. The application of concepts with multiple antennas necessitates the introduction of more advanced and computational expensive transmitter and receiver structures, where space-time (ST) processing techniques are required to carry out spatial and temporal information processing jointly. This article introduces a new ST processing concept to enable reduced dimension ST receiver signal processing. The signal dimension can be considerably reduced compared to the number of antennas by exploiting spatial correlation properties of the received antenna signals. The associated signal transformation applies the concept of the Karhunen-Loeve transformation (KLT). A great advantage of the proposed ST processing concept over traditional multiple antenna approaches is the insensitivity of the algorithms to the antenna characteristics and antenna spacing, which allows the use of low-cost antennas. Another significant advantage of the proposed concept is more robust channel estimation due to spatial dimension reduction and the resulting limitation of estimation parameters. [ABSTRACT FROM PUBLISHER]

3G wireless systems are still in the early stages of development. In fact, it may be another five to 10 years before we know their full market impact. However, there are already limitations and problems. Some of these problems are technical in nature, while others are business-related. Getting different access networks to interoperate in a seamless manner without a fixed infrastructure still holds many challenges. High data rates and adequate bandwidth to handle multimedia applications like full-motion video and wireless teleconferencing still need work. [ABSTRACT FROM PUBLISHER]

We have investigated three interferometric all-optical switches based on cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs), the semiconductor laser amplifier in a loop mirror (SLALOM) switch, the Mach-Zehnder interferometer (MZI) switch, and the ultrafast nonlinear interferometer (UNI) switch. Switching windows with different widths are measured under similar conditions for all three switching configurations. We introduce the integrated contrast ratio (ICR) as a measure to evaluate the performance of a switch from switching windows. Using the ICR, the switches are compared and their application is discussed as demultiplexer in optical time division multiplexing (OTDM) systems for data rates of 40, 80, and 160 Gb/s [ABSTRACT FROM PUBLISHER]

We demonstrate an elementary grating-based optical code division multiple access (OCDMA) code generation and recognition system incorporating a nonlinear optical loop mirror (NOLM) within the receiver. We show that the NOLM can act as a nonlinear processing element capable of reducing both the pedestal associated with conventional matched filtering and the width of the associated code-recognition pulse. The pedestal rejection allows for an improved code recognition signal-to-noise ratio (SNR) relative to simple matched filtering alone, and reduced intra- and interchannel interference noise due to code overlap. The system benefits of using the NOLM are experimentally demonstrated under both single- and multiuser operation within a variety of seven- and 63-chip 160-Gchip/s code generation, recognition, and transmission experiments based on the use of bipolar superstructure fiber Bragg grating (SSFBG) coding-decoding pairs. Incorporation of the NOLM is shown to allow error-free penalty-free operation at data rates as high as 2.5 Gb/s under single-user operation, and to provide error-free performance with reduced power penalty in two-user experiments. The narrowed pulse recognition signature offers major advantages in terms of the further all-optical processing of decoded signals, such as code regeneration and recoding [ABSTRACT FROM PUBLISHER]

Combining fiberoptics for point-to-point communication and millimeter waves for short-range wireless communication simultaneously provides fast data rates, high security levels, and mobility. The article describes the system architecture, including some of the key design tradeoffs that have been and are currently being considered, and the demonstration/validation (DEMVAL) results. Highlights of the progress include the transmission of data, digital video, and voice from a fixed computer terminal to a portable/wearable computer over the hybrid fiberoptic/millimeter-wave link. These results demonstrate system architecture proof-of-concept as well as significant risk reduction in critical subsystems [ABSTRACT FROM PUBLISHER]

The current status of lithium-niobate external-modulator technology is reviewed with emphasis on design, fabrication, system requirements, performance, and reliability. The technology meets the performance and reliability requirements of current 2.5-, 10-, and 40-Gb/s digital communication systems, as well as CATV analog systems. The current trend in device topology is toward higher data rates and increased levels of integration. In particular, multiple high-speed modulation functions, such as 10-Gb/s return-to-zero pulse generation plus data modulation, have been achieved in a single device [ABSTRACT FROM PUBLISHER]

Third-generation wireless systems call for strategies that can improve achievable performance and data rates while providing flexibility and affordability. Software-defined radio technology is promising to provide the required flexibility in radio frequency, intermediate frequency, and baseband signal processing stages. Baseband signal processing techniques such as interference cancellation for direct-sequence code-division multiple access systems have the potential to provide the higher performance requirements of 3G systems. With advances in digital signal processor technology, the gap between the complexity of interference cancellation algorithms and available processing speeds is narrowing. However, 3G system requirements are ever pushing the envelope of signal processing algorithms required, including multi-user detection schemes, that are considered to be attractive and viable candidates. WINLAB has been working on an attractive SDR solution, to provide flexibility and handle the processing speeds required of 3G radio receivers. The approach is based on SDR architectures that partition radio receiver processing into two core technologies (field programmable gate arrays and DSP devices). We present a summary of the SDR work at WINLAB that is based on using this mixed signal processing approach for implementation of nonlinear interference cancellation and linear multi-user detection algorithms [ABSTRACT FROM PUBLISHER]

Throughout 1998, the TDMA community investigated and defined an enhanced suite of voice and data services for TIA/EIA-136 while also improving its basic system capabilities. These enhancements, collectively named 136+, provide improved voice quality, increased capacity, higher data rates, and improved tools for RF system engineering. The enhancements are obtained by introducing a new modulation scheme (8-PSK), new slot formats, and the addition of several new interleaving and coding options. As a result, TIA/EIA-136 now supports a new vocoder mode, the GSM enhanced full-rate (US1) for improved fidelity applications, a robust IS-641 vocoder mode with a 4 dB BER enhancement on the IS-136 downlink, and a new packet data service capable of providing usable data rates of 14.4, 28.8, or 43.2 kb/s on a full-rate, double full-rate, or triple full-rate channel, respectively. The packet data service is truly evolutionary in nature, having a new medium access control layer with a network layer very similar to that used for the existing digital control channel. In addition, it maximizes commonalities among TDMA technologies, using identical higher layers and network architecture to the general packet radio service specified in GSM. Furthermore, by using a concept known as tunneling to pass TIA/EIA-136 messages through the GPRS network elements, the existing features defined on the DCCH are maintained. This article provides an overview of these 136+ applications, as well as insight into near-term improvements, such as the ability to support six voice users per 30 kHz (IDMA6), downlink time diversity, and fast power control [ABSTRACT FROM PUBLISHER]

This article provides an overview of the flexible, high-performance packet data channel that has been designed for high-rate packet data services over IS-136 TDMA channels. To achieve the highest data rates in the limited 30 kHz channel bandwidth, the packet data channel is designed for adaptive modulation and, in addition to a fixed coding mode, permits operation using an incremental redundancy mode [ABSTRACT FROM PUBLISHER]

A silicon microring modulator for ON-OFF keying intensity modulation is presented and experimentally characterized. Modulation operation is based on carrier depletion effect in a p-n junction. The resonance wavelength shift is measured for bias voltages in the range between 0 and -7 V and modulation is demonstrated by employing electrical signals with data rates of 25 and 30 Gb/s and peak-to-peak voltage of 3.75 V. Performance in terms of bit error rate as a function of the optical signal-to-noise ratio for point-to-point transmission over 10 km of single mode fiber at both the data rates is experimentally evaluated, manifesting to be suitable for short- and medium-reach optical interconnects applications. [ABSTRACT FROM PUBLISHER]

Most of the current research work on the Narrowband Internet of Things (NB-IoT) is focused on enhancing its network coverage. Many of the existing NB-IoT channel coding techniques are based on repeating transmission data and control signals as a way of enhancing the network's reliability and therefore, enabling long-distance transmissions. Although most of these efforts are made at the expense of reducing the energy consumption of the NB-IoT network, they do not always consider the channel conditions. Therefore, this work proposes a novel NB-IoT Energy-Efficient Adaptive Channel Coding (EEACC) scheme. The EEACC approach is a two-dimensional (2D) approach which not only selects an appropriate channel coding scheme based on the estimated channel conditions (dynamically classified as bad, medium or good from initial based on a periodically assessed BLER performance outcome) but also minimizes the transmission repetition number under a pre-assessed probability of successful transmission (based on the ratio of previous successful transmissions over the total number of transmissions). This results in creating a single mixed gradient based on which a higher or lower Modulating Coding Scheme (MCS) is selected on each transmission. It is aimed at enhancing the overall energy efficiency of the network by dynamically selecting the appropriate Modulation Coding Scheme (MCS) number and efficiently minimizing the transmission repetition number. Link-level simulations are performed under different channel conditions (good, medium, or bad) considerations to assess the performance of the proposed up-link adaptation technique for NB-IoT. The obtained results demonstrate that the proposed technique outperforms the existing Narrowband Link Adaptation (NBLA) as well as the traditional repetition schemes in terms of the achieved energy efficiency as well as network reliability, latency, and scalability. [ABSTRACT FROM AUTHOR]

A new kind of modulating retro-reflector using cat's eye optics and a multiple quantum-well electro-absorption modulator array is described. The device exhibits retro-reflection over a 30° field of view and can support data rates of up to 50 Mb/s using 1-mm pixels. The use of the device in free-space optical communication is discussed. [ABSTRACT FROM PUBLISHER]

In high-rate wireless LAN, complementary code keying (CCK) is adopted in the IEEE 802.11b standard to support data rates up to 11 Mbps, much higher than the 2-Mbps data rate in the previous wireless LAN standard. Due to less-than-ideal characteristics of the CCK codewords, the CCK performs quite poorly in large-delay-spread multipath channels. In this paper, a new modulation scheme that combines the trellis coding with the CCK modulation is proposed. This scheme is shown, through simulation, to achieve much better error rate performance in medium-to-large channel delay spread environments [ABSTRACT FROM PUBLISHER]

Today's wireless core network is based on a circuit-switched SS7 architecture similar to that found in wireline telecommunications networks. With the advent of IP technologies and the tremendous growth in data traffic, the wireless industry is evolving its core networks toward IP technology. Wireless telecommunications started as an offshoot of wireline telephony, and the absence of global standards resulted in regional standardization. Two major mobile telecommunications standards have dominated the global wireless market, namely, TDMA/CDMA developed by the TIA in North America and GSM developed by the ETSI in Europe. As we move toward third-generation wireless, there is a need to develop standards which are more global and collaborative. The global wireless industry has created two new global partnership projects, SGPP and 3GPP2, to address the issue of the limited data capabilities of 2G systems, motivating the partnership projects (PPs) to start work on 3G wideband radio technologies that can provide higher data rates. This work resulted in 3G wireless radio technologies that will provide data rates of 144 kb/s for vehicular, 384 kb/s for pedestrian, and 2 Mb/s for indoor environments, and meet the ITU IMT-2000 requirements. Now that the radio technology standards to support higher data rates have been developed, the PPs are focusing on development of standards for all-IP networks. We discuss the genesis of 3GPP and 3GPP2 IP work, outlining the important architectural differences of the two groups. Currently, 3GPP and 3GPP2 offer divergent proposals that need to be harmonized if convergence toward an IP-based mobile telecommunications networks is to become a reality [ABSTRACT FROM PUBLISHER]

Perfluorinated graded-index polymer optical fibers (GI-POF's) have been developed that offer low losses (<50 dB/km) and high bandwidth (>0.3 GHz km) at data communication wavelengths (0.85 and 1.3 μm). Here we demonstrate that such fibers can support data rates up to 11 Gbit/s for 100 m with low-power penalty and large-power margins. Although a restricted launch was used, differential mode delay measurements show that, in a large central region of the fiber core (50% of the core diameter), very large bandwidths can be obtained with modest alignment requirements. These improved transmission characteristics (obtained using inexpensive, uncooled, unisolated 1.3-μm Fabry-Perot sources and pin detectors) together with potential low-cost connectorization and a small fiber bend-radius make perfluorinated GI-POF's a candidate for premise networks and short-reach telecom and computer interconnections [ABSTRACT FROM PUBLISHER]

Optical networks which are rapidly reconfigurable and bit-rate transparent require agile clock and data regeneration (CDR) circuits that can respond quickly to different bit-rates. Real-time optical packet switching will also require burst-mode response. Present CDR techniques can be modified to rapidly synchronize to burst data if they are first tuned to the desired bit-rate. We propose and demonstrate a rapid-response bit-rate detection and selection circuit which can handle a discrete and continuous range of data rates from 10 Mb/s to 1.3 Gb/s. The circuit is suitable for programming conventional and burst mode CDR functions in regeneration, line termination, and real-time switching applications [ABSTRACT FROM PUBLISHER]

We have fabricated vertical-cavity surface-emitting lasers (VCSELs) which, for the first time, effectively combine a shallow ion implanted aperture, for current confinement under a thin highly conducting lateral current injection layer, and an independent index guide for optical beam confinement (I2-VCSELs). Both features are possible only because they are made before a top dielectric mirror is deposited and patterned, and are photolithographically defined for improved size reproducibility compared to oxide-confined designs. The devices emit near 980 nm and have optical power outputs of 1 mW at 2.5-mA input. The 12-VCSEL design also easily incorporates coplanar contacts allowing us to operate flip-chip bonded I2-VCSEL's on silicon test chips at data rates of nearly 1 Gb/s [ABSTRACT FROM PUBLISHER]

A photoreceiver optoelectronic integrated circuit based on InP with a bandwidth of 37 GHz is presented. The receiver consists of a 50 GHz waveguide-integrated photodiode and a distributed amplifier with a bandwidth of 39.5 GHz, which is composed of four high-electron mobility transistors. A system experiment at 40 Gb/s receiving an return-to-zero coded optical input signal is demonstrated, and a good quality of eye pattern is achieved [ABSTRACT FROM PUBLISHER]

We describe a method for estimating achievable data rates in urban microcells using multiple-input/multiple-output (MIMO) techniques. Specifically, we use site maps and a versatile ray-tracing tool to compute MIMO gain matrices as a function of terminal location; and we use these matrices to determine achievable rates for various MIMO transmission modes (spatial multiplexing, beamforming, and diversity). Numerical results are generated for specific paths in Boston and Manhattan, though our results are shown to be fairly insensitive to neighborhood or city. We also show that, in urban microcells, data rate prediction using site-specific ray tracing is more informative than using stochastic models; and that adaptive switching among MIMO transmission modes as a terminal moves along its trajectory can help sustain high data rates. A new mode-switching algorithm is proposed that requires switching rates lower than those for the optimal scheme by a factor greater than 10, with little loss in average data rate. We also propose a novel software algorithm for optimally placing microcell bases. For a Manhattan neighborhood of area 0.5 km^2, we find that full coverage can be obtained using only 5 bases, and that the highest total throughput is achieved using a frequency reuse factor of 1. [ABSTRACT FROM PUBLISHER]