Showing papers in "Communications Engineer in 2004"

The design of CMOS radio-frequency integrated circuits, 2nd edition

Abstract: 53 ■ IEEE CIRCUITS & DEVICES MAGAZINE ■ NOVEMBER/DECEMBER 2005 THE DESIGN OF CMOS RADIOFREQUENCY INTEGRATED CIRCUITS, 2ND ED By Thomas Lee, Cambridge University Press, 2003. All-CMOS radio transceivers and system-on-a-chip are rapidly making inroads into a wireless market that, for years, was dominated by bipolar solutions. On wireless LAN and Bluethooth, RF CMOS is especially dominant, and it is becoming also in GSM cellular and GPS receivers. Hence, books that cover this widespread domain respond to a real need. The first edition of this book, published on 1998, was a pioneering textbook on the field of RF CMOS design. This second edition is a very interesting and upgraded version that includes new material and revised topics. In particular, it now includes a chapter on the fundamentals of wireless systems. The chapter on IC components is greatly expanded and now follows that on passive RLC components. The chapter on MOS devices has been updated since it includes the understanding of the model for the shorth-channel MOS and considers and discusses the scaling trends and its impact on the next several years. It has also expanded the topic of power amplifiers; indeed, it now also covers techniques for linearization and efficiency enhancement. Low-noise amplifiers, oscillators, and phase noise are now expanded and treated with more detail. Moreover, the chapter on transceiver architectures now includes much more detail, especially on direct-conversion architecture. Finally, additional commentary on practical details on simulations, floorplanning, and packaging has been added. The first edition of this book widely covered all the main arguments needed in the CMOS design context and provided a bridge between system and circuit issues. This second edition, which is upgraded and improved, is really useful, both in the industry and academia, for the new generation of RF engineers. Indeed, it is suited for students taking courses on RF design and is a valuable reference for practicing engineers. Of course, the arguments treated in the textbook lead up to low-frequency analog design IC topics. Hence, readers have to be intimately familiar with that subject. The book is divided into 20 chapters: 1) A Nonlinear History of Radio 2) Overview of Wireless Principles 3) Passive RLC Networks 4) Characteristics of Passive IC Components 5) A Review of MOS Device Physics; 6) Distributed Systems 7) The Smith Chart and S-Parameters 8) Bandwidth Estimation Techniques 9) High-Frequency Amplifier Design 10) Voltage References and Biasing 11) Noise 12) LNA Design 13) Mixers 14) Feedback Amplifiers 15) RF Power Amplifiers 16) Phase Locked Loop 17) Oscillators and Synthesizers 18) Phase Noise 19) Architectures 20) RF Circuits Through the Ages. Moreover, it contains over 100 circuit diagrams and many homework problems. Gaetano Palumbo

What exactly is . . . ZigBee

Abstract: A new wireless technology named ZigBee is being launched onto the market. However, with Bluetooth, 802.11a, b and g, ultra wideband (UWB) and many more, there may seem to be a surfeit of wireless systems. Already a number of standards, such as HomeRF, have gone by the wayside, and others are sure to follow. But can ZigBee live up to its expectations? Aimed at control and sensor applications, ZigBee is a superset of the IEEE 802.15.4 specification, which defines the physical and MAC layers. Above this, ZigBee defines the application and security layer specifications that enable interoperability between products from different manufacturers. ZigBee supports three network topologies - star, mesh and cluster tree or hybrid networks. The article outlines the specification's foundations. It concludes that, in view of the size of this market, and the way in which considerable wiring cost savings can be realised, ZigBee has a good chance to carve out its own niche in the marketplace. Having already made an impact in the US, it is likely to be around for some time to come.

WiMAX in-depth [Broadband wireless access]

Abstract: IEEE 80216 is an emerging air-interface standard providing last-mile broadband wireless access This unifying standard - fundamentally different from IEEE 80211 and Wi-Fi - brings the promise that companies will see a return on investment and benefit from the long-awaited hope of equipment interoperability IEEE 80216 has industry representation in the form of the WiMAX (Worldwide Interoperability for Microwave Access) forum The article gives a technical view of the various elements that gave birth to the WiMAX standard

Designing buildings for the wireless age [FSS]

Abstract: A new breed of construction materials with the ability to manage RF signals is set to rock the foundations of the building industry. People at work today are demanding a communications infrastructure that is both universally accessible - therefore including mobility - and secure. But meeting both of these requirements simultaneously can present a considerable challenge. Currently, mobile communication networks and systems are designed on the basis of detailed analysis of RF coverage and capacity requirements. Security and privacy issues can be addressed through good design, but 'eavesdropping' remains a real vulnerability. An emerging technology named FSS (frequency selective surface) is increasingly being proposed as an answer to the deployment of secure wireless systems for indoor environments, taking advantage of innovative techniques in building design and the use of attenuating materials. The signals for indoor systems are attenuated, while those for wider networks are not.

Broadband from heaven [high altitude platforms]

Abstract: It has always been a dream of communications engineers to be able to develop a wireless network that, while covering a wide area, would also have low propagation delay and little multipath fading. Recently, a new way for providing wireless communications services has emerged. Based on airships or aircraft positioned in the stratosphere at altitudes from 17 to 22 km, the technology is known as high altitude platforms (HAP) or stratospheric platforms (SPF). HAPs have most of the advantages of both terrestrial and satellite systems, while they avoid some of their drawbacks. The most important disadvantages of HAPs lie in the immature airship technology and the monitoring of the platform's movement. The article discusses the types of airships or aircraft that may be used, spectrum allocation, network design, rain attenuation, interference, antenna system design and potential applications. In spite of their outstanding features, several factors have so far hampered the deployment of HAP systems. Convincible demonstrations of their usefulness are necessary, as well as further development in antenna, airship and unmanned aircraft technologies.

We know where you are [Location tracking]

Abstract: New services, which bank on cellular networks being able to determine handset position accurately, are said to be the next holy grail for mobile operators. The article describes the main technical flavours and their prospects. There are various practical techniques used to determine the location of a mobile phone. The main ones are: cell identify (cell-ID); enhanced cell ID (e-cell ID); angle-of-arrival (AOA); time-of-arrival (TOA) and time-difference-of-arrival (TDOA); enhanced observed time difference (E-OTD); assisted Global Positioning System (A-GPS); signal strength; hybrid techniques. In order to compare expected theoretical results with real-world performance, we set up a series of field trials based on one of these location finding techniques. Experiments were conducted in both urban and rural environments. The experiment measured the level of accuracy provided by cell-ID with an exclusive GSM parameter (timing advance, or TA), using triangulation.

Coach potato [TV on mobile phones]

Abstract: The inevitable arrival of TV broadcasts on mobile phones moves a step closer. The DVB-T (digital video broadcasting-terrestrial) transmission system has proven its ability to serve both fixed and portable terminals in the various networks it has been deployed. In some networks such as Berlin and Singapore, even mobile terminals are supported. What the standard has been missing is support for handheld terminals, which require specific features from the transmission system. In January 2003, work began on a new version of the standard: DVB-H (DVB handheld). Following a period of consultation and proposals from various industry players, work was completed in January 2004, and the draft standards sent to ETSI for final approval. The article describes the properties of the draft DVB-H system. The specification has been verified via computer simulations, but real-world measurements and tests are yet to be made. Once the pilot phase is complete, it is expected that countries which have adopted DVB-T will see the introduction of commercial services complementing the emerging technology within two to five years.

True broadband for the countryside [5GHz cognitive radio]

Abstract: Although Canada holds one of the world's highest Internet take-up rates, 22% of the population still cannot receive broadband services Canada's wireless community warmly welcomed a recent regulation set by the World Radio Congress (WRC) In June 2003, the WRC allocated new bands at 5250 to 5350 MHz and 5470 to 5725 MHz for unlicensed wireless access applications The new bandwidth offers the promise of affordable broadband wireless built to global standards The allocation and the technologies that support it may offer a viable "last mile" solution to regions around the world that are disadvantaged because of remoteness, cost or lack of infrastructure The article describes the work done by the Canada's Communications Research Centre (CRC) to investigate the use of 5 GHz for rural community applications as part of its rural and remote broadband access programme

3G killer apps everywhere

Abstract: The wireless industry has been searching for 'the' killer application ever since the idea of 3G was proposed. Could it be video calls? Or is it email? How about multimedia messaging? Or perhaps the 3G killer application is a sort of cocktail, a suite or selection of services? The article discusses some of the services which are being introduced around the world.

A clearer channel for SMS

Abstract: Signaling System 7 (SS7) is a global standard that defines the signaling architecture and protocol used by public switched telephone networks (PSTN). Call setup, call forwarding, toll-free calling and customer billing are some of the common functions of SS7. Also called the "out-of-band" network, SS7 is separate from the voice channel. Its network architecture defines a set of nodes that provide the network entry points, switches for routing and databases for accessing call information. The proliferation in the use of mobile phones and, particularly, of short message service (SMS) technology has created a new form of network congestion, marked by sporadic bottlenecks directly caused by SMS which transmits data across the out-of-band SS7 data network. There are two ways to alleviate SMS congestion in SS7 networks. One method is to add more equipment but this is cost-prohibitive. A more economical and efficient approach is to increase the capacity of each signaling link. This can be done using clear channel SS7. Clear channel SS7 is defined by ITU specification Q.703 Annex A. Its link combines multiple channels to form a pipe, thus greatly increasing the capacity of the link. This expands network capacity for handling calls and SMS traffic without adding extra hardware.

ADSL2: a sequel better than the original?

Abstract: The growing number of applications based on IP network infrastructure has introduced the need for greater symmetry in broadband connectivity. Following the rapid success of ADSL deployments around the world, a new flavour of the standard, ADSL2, is promising more than double upstream rates and backward compatibility with existing customer premise equipment (CPE). Based on a series of measurements performed on a real-life testbed network, it is possible to get a valuable insight into the performance and interoperability capabilities of ADSL2 technology. The evaluation of the results indicates that the migration towards an ADSL2 infrastructure can be both economically viable and technologically efficient, even without upgrading existing CPEs. This offers the provider a cost-effective solution to address growing customer needs while keeping in pace with the advancing technology.

Super-locator [RFID tracking]

Abstract: The noise surrounding radio frequency identification (RFID) technology, the bar code's natural successor for tracking goods through the supply chain, is getting louder by the minute. A plan by fashion chain Benetton to embed RFID tags in garments had to be abandoned following a campaign that suggested the tags pose an invasion of privacy by tracking an individual's buying habits. On a more positive note, the Auto-ID Centre, funded by over 100 companies, completed its four-year mission. The result of its work was the emergence of EPC Global, a body with the mission to promote electronic product code (EPC) technology and specifications. Unlike bar codes, RFIDs employ radio frequencies to transmit data to readers within a certain distance. There are three RFID ranges: low-frequency (125 kHz or 134 kHz); high-frequency (13.56 MHz); ultrahigh-frequency (UHF) (300 MHz to 1 GHz). Most RFID applications have used low-frequency or high-frequency tags, not UHF, but supply chain applications will need the longer range that UHF provides. Besides standards and privacy concerns, the cost of tags and readers and their reliability are impediments to commercial implementation. The article discusses these issues.

High-speed security [Embedded security]

Abstract: Most companies today take the risks of unwanted network intrusion, theft, sabotage and malicious damage very seriously Historically, only high-end networking equipment required, or could justify, the additional cost of implementing security features onto a final network design However, the explosion of home networking and the growing number of connected users, and hence possible system attacks, have produced a widespread requirement for low-cost, high-performance security solutions Different applications have, of course, different security requirements for data privacy, integrity and authentication In today's communications networks, populated by applications demanding increasing amounts of bandwidth, the ultimate goal of a transparent security processing solution in the end system is impossible to achieve through software A high-performing secure solution can only be achieved through the use of some form of hardware assistance, specifically designed to off-load the main CPU or network processor from performing the required mathematically intensive security algorithms The article reviews some of the options

Low-power transceivers get patients mobile [Wireless medical applications]

Abstract: The growing use of radio communications to monitor medical conditions is making life easier for patients and their carers. Wireless systems enabled by low-power radio technology are delivering mobility, higher levels of patient care and relative comfort inside and outside the medical facility environment. Both 'on-the-skin' and implantable medical electronic devices are benefiting from transceivers that use the latest mixed-signal ASIC technology to provide desired rates of data transfer over short ranges. Electronics used in medical environments - especially implanted devices - need to have a low-power consumption and high reliability design. Low-power radio devices that use ASICs are already starting to be specified in applications such as cardiac pacemakers, blood glucose monitoring and body temperature sensing. There are two protocols that relate to devices of this type. The first is known as medical implant communications services (MICS). It applies to implantable technologies that need to communicate with the outside world periodically, or when there is a deviation from specified parameters. The second is wireless medical telemetry service (WMTS), which deals with non-implanted (on-the-skin) patient monitoring systems that communicate on a far more regular, timed basis with a suitably equipped remote location, such as a nursing station. Present designs and the future of such systems are discussed.

UWB: the start of a dark age?

Abstract: Time is running out before the global radio community makes a decision that could have drastic consequences for the wireless establshment.

The clearest voice [IP telephony]

Abstract: IP telephony is on its way to succeeding the World Wide Web as the next breakthrough application for all-IP networks. Two standards are currently competing for dominance in IP telephony - the H.323 protocol suite by the International Telecommunication Union (ITU) and the session initiation protocol (SIP) by the Internet Engineering Task Force (IETF). Both protocols exchange multimedia data over the real time protocol (RTP), so the choice of protocol suite does not influence Internet telephony QoS. However, H.323 and SIP do differ in a range of implementation aspects. The article examines these differences. It finds that SIP has clear advantages over H.323. It is more powerful, modular and extendable. It has been gaining in popularity, especially in North America and with new entrants into the VoIP market. However, H.323 has the advantage of being implemented first, which resulted in many of the early VoIP adopters embracing it. This situation makes it hard to simply conclude on one winning technology over the other. Instead, there will be a need for interoperability between SIP and H.323 signaling, for interconnection between different existing VoIP networks and PSTN/ISDN legacy deployments.

Roaming from on G to another [Inter-RAT handover]

Abstract: The introduction of 3G technology brings a range of previously unavailable multimedia services to the mobile user However, it also presents operators and equipment designers with a number of fresh challenges One of these challenges is that, until complete 3G coverage is achieved, if it ever occurs, users will depend on the existing 2G/25G networks to ensure complete coverage To achieve this, they will need to roam ubiquitously and seamlessly between the two different radio access technologies (RAT) Inter-RAT (or intersystem) handover is the process of maintaining a phone connection while moving from one cell to another of different RAT A number of solutions have been developed to overcome the problems specifically associated with inter-RAT handover between UMTS and GSM/GPRS The article discusses some of them

The challenge of keeping applications secure [3G testing]

Abstract: 3G could replace the Internet as the primary target for the armies of highly intelligent and capable hackers that continuously seek security loopholes in company IT networks, Web sites and even home users with always-on broadband access The article covers the technical aspects surrounding 3G security and the common risk scenarios that are already being encountered by major network and application developers

Avoiding the downhill [cellular voice quality]

Abstract: A study has been carried out to find out how the voice quality offered by four cellular networks in the USA compared both to each other and to the traditionally high standards attained by the local telephone companies (PSTNs). There was a measurable difference in quality among the different operators, particularly in the downlink section (traffic moving from the PSTN to the wireless user). The second clear finding is that the downlink consistently outperforms the uplink in all networks. This should not come as a major surprise considering that the party regularly paying the operator's bill at the end of each month is the wireless user and not those at the other end of the line. The question of how much worse voice quality really is in the cellular world compared to that of the incumbents also received a resounding answer: a full listening quality MOS (mean opinion score) point when the average overall performance for the four networks is considered (3.3 MOS versus the accepted 4.3 MOS level shown by typical PSTNs). Another interesting discovery was that a mobile phone indicating good signal reception will not necessarily translate into increased voice quality.

Smile for the (wireless) camera [Digital broadcasting]

Abstract: The advent of new digital technologies and the use of innovative electronic design is starting to provide the broadcast industry with reliable solutions, offering perfect pictures and unlimited flexibility. The development of digital wireless camera systems over the last two years is finally freeing the cameraman from the constraint of the umbilical cable.