Wireless infrared communications with edge position modulation for mobile devices

Driven by the Infrared Data Association, wireless infrared communication has become a very popular and widely used method for short-range data transmission between mobile devices like laptops, PDAs, and mobile phones. Especially in ad hoc connection applications, IrDA excels over radio-based solutions like Bluetooth or cable-based solutions like USB, due to the point-and-shoot characteristic of infrared communication. The quality and speed of infrared communications are mainly limited by the bandwidth of infrared transceivers. Therefore, it is important to use a modulation technique with high bandwidth efficiency, while simultaneously maintaining a low bit error rate and high power efficiency. Consequently, the IrDA has continuously improved the modulation techniques of its standards by introducing return to zero inverted (RZI) for the serial infrared (SIR) mode, 4-PPM for the fast infrared mode, and HHH(1,13) for the latest very fast infrared mode. This article presents a new modulation scheme called edge position modulation (EPM) with RLL coding, which offers increased bandwidth efficiency over the previous methods and attractive power efficiency. Since the novel modulation technique can be optimized to the characteristics of the wireless infrared channel, it also maintains low bit error rates.     

Wireless data communications

Wireless data services and systems represent a rapidly growing and increasingly important segment of the communications industry. In the paper the authors present an overview of this field, emphasizing three major elements: (1) technologies utilized in existing and currently planned wireless data services, (2) issues related to the performance of these systems, and (3) discernible trends in the continuing development of wireless data systems. While the wireless data industry is becoming increasingly diverse and fragmented, one can identify a few mainstreams which relate directly to users requirement for data services. On one hand, there are requirements for relatively low-speed data services supporting mobile users over wide geographical areas, as provided by mobile data networks. On the other hand, there are requirements for high-speed data services in local areas, as provided by wireless LANs. The system-level issues are somewhat different for these two categories of services, and this has led to different technology choices in the two domains, which the authors discuss in the paper     

Wireless multicarrier communications

Relying on basic tools such as eigensignals of linear time-invariant systems, linear and circular block convolution, and fast Fourier transforms (FFTs), this article develops a systematic discrete-time framework and designs novel systems for single- and multiuser wireless multicarrier communications-a field rich in signal processing challenges that holds great potential in various applications including audio/video broadcasting, cable television, modem design, multimedia services, mobile local area networks, and future-generation wideband cellular systems. Wireless multicarrier (MC) communication systems utilize multiple complex exponentials as information-bearing carriers. MC transmissions thus retain their shape and orthogonality when propagating through linear time-dispersive media, precisely as eigensignals do when they pass through linear time-invariant (LTI) systems     

Wireless communications — the fundamentals

The primary aim of this paper is to provide an overview of wireless communication fundamentals, and the approach used considers them within the context of the following four categories — radio propagation, wireless air interface, advanced antenna systems and interference effects. In addition to this, a representative set of mobile systems are compared to show that their differences are primarily due to them having different combinations of channel transport, modulation scheme and regulatory constraints on transmit power, channel bandwidth, operating frequency and channel duplex.     

Wireless communications + + +

Commencing with the advancements that may be expected in 3G during the first decade of this century, we move on to anticipate subsequent developments based on what society might need and the technologies that may be required. The near demise of mobile satellite networks and removal of radio broadcasting from potential mobile radio bands will provide the necessary bandwidth for high capacity, high quality multimedia mobile services utilising a dense concentration of fibre networks coupled to radio cells of all sizes. The integration of many factors from high aerial platforms (haps) (that are located in the stratosphere and from terrestrial cells that can be adjusted in size and moved instantly to suit teletraffic changes) to picocells, body-LANs to the fixed network, software agents to soft telecommunications, will be discussed. Finally the possibility of our networks metamorphosing into a global brain, and how man-kind might adapt to this supra-intelligence will be addressed.     

Electronic tracking for wireless infrared communications

A high-speed wireless system (/spl ges/100 Mb/s) for indoor infrared (IR) communications via the line of sight is described and feasibility is shown in an experimental demonstrator. A diffuse link is used for connectivity, and tracked directed links are used for high-speed communications. The transmitter is made of a laser diode array in combination with multiple-beam forming optics. For the receiver (Rx), a wide-angle lens, and an avalanche photodiode array are used. For the diffuse link, the signals from all pixels in the array are combined. Pixels are selectively addressed to realize directed links. Fast electronic tracking of a directed link is possible by switching the signal path onto the right pixel in the array. Diffuse link, directed link, position detection, and tracking can be realized with one and the same transceiver hardware. A favorite system design is derived from constraints due to the IR channel, eye safety, lenses, photodetectors, and the overall system complexity. The experimental system shows some key features, namely 155-Mb/s wireless transmission over a distance of nearly 2 m with electronic tracking at an imaging IR Rx. Electronic tracking of IR links, thus, allows both high data rates and high capacity for wireless access in small office and home environments.     

Wireless ultrawideband communications and sensor networks

An actively advancing branch of wireless ultrawideband communications is considered. Direct chaotic transceivers of two types are described. The transceivers were developed at the Institute of Radio Engineering and Electronics, Russian Academy of Sciences. Application of these transceivers in wireless sensor networks is demonstrated.     

Trellis-coded multiple-pulse-position modulation for wireless infrared communications

We present new trellis codes based on multiple-pulse-position modulation (MPPM) for wireless infrared communication. We assume that the receiver uses maximum-likelihood sequence detection to mitigate the effects of channel dispersion, which we model using a first-order lowpass filter. Compared to trellis codes based on PPM, the new codes are less sensitive to multipath dispersion and offer better power efficiency when the desired bit rate is large, compared with the channel bandwidth. For example, when the bit rate equals the bandwidth, trellis-coded (17 2)-MPPM requires 1.4 dB less optical power than trellis-coded 16-PPM having the same constraint length.     

Wireless communications and networking: an overview

This paper presents an overview of wireless local-area networks (LANs) and wireless personal area networks (PANS), with emphasis on the two most popular standards: IEEE 802.11, and Bluetooth. While there are many such surveys in the current literature and online, we attempt here to present wireless LANs and PANS in a unified fashion as a viable alternative to wired LANs, while stressing the remaining challenges and limitations     

Wireless communications in the automated factory environment

The networking issues involved in the use of infrared communications in a factory environment are described. A brief history of the use of infrared and radio for indoor (factory environment) communications is given, and the physical infrared environment is reviewed. Topology and protocol alternatives are compared     

Wireless communications: a decade of progress

The enormous progress of wireless technology during the last ten years and the lack of institutional mechanisms for coping with the fast-paced change in technology are discussed. The fracturing of the cellular industry due to the lack of a single standard and the emergence of personal communication services based on the cordless phone are examined     

Wireless personal communications: trends and challenges

The rapid expansion of the field of wireless personal communication services is described, focusing on statistics showing demands and on recent events on the industry. Some propagation research results that should have an impact on the design and implementation of future cellular and personal communication services are surveyed. A number of antenna and propagation research problems which need to be solved to improve the spectral efficiency, and thus the system capacity, of emerging high-density personal-communication systems are discussed     

IrDA infrared wireless communications: protocol throughput optimization

The delivery of the maximum data rate to users from IrDA IR wireless links depends not only on the physical layer, but also on higher-layer protocols being optimized. This article reviews the IrDA link layer protocol, IrLAP, and examines how to maximize its throughput performance. Simple equations yield to simple rules for the optimization of IrLAP. The analysis presented can also be employed in studying the physical layer requirements of the predicted future data rate increases (40 Mb/s and 100 Mb/s) of the IrDA 1.x standard. The model gives insights for the optimum control of the infrared connection for high performance. Simple formulas are derived for the optimum values of the window and frame size link layer parameters that maximize throughput. Results show that, for the proposed 16 Mb/s extension, significant throughput increase is observed if optimum link layer parameter values are employed. At high error rates, the significance of the minimum turnaround time (a physical layer parameter) and of the transmission control passing mechanism is studied. When the links are adapted to using the optimum window and frame size, combined with low minimum turnaround values and an efficient transmission control passing scheme, we observe performance improvements even at high error rates.     

Wireless broadband communications: some research activities inSingapore

Almost a decade ago, Singapore started crafting and implementing its IT2000 master plan to transform the city-state into an information-technology-based intelligent island. Since 1997, the main infrastructure of a high-speed ATM-based backbone network, called SingaporeONE, has been in place along with a host of commercial and governmental application service sites providing a plethora of online services. Because of its small size and extensive wired infrastructure, broadband access to homes and offices is currently provided via ADSL and cable modems. There is, however, interest in the use of wireless broadband communication technologies to access SingaporeONE, motivated primarily by its lower cost and faster deployment. In this article we describe some of our R&D activities motivated by the above interest to provide wireless broadband access to SingaporeONE. Specifically, we describe our study of LMDS, and the design and development of a wireless ATM LAN