Technical Articles and Whitepapers

Links to technical articles at other sites that we found of interest.

Connecting with a Bluetooth Piconet - This overview explains many of the paging and integration processes that take place between devices in a Bluetooth piconet.

Wireless Data Communications Application Guide Contains a very good explanation of the different types of Spread Spectrum communications- Micrilor

Spread Spectrum Technology in Wireless Telecommunication Networks - Spread spectrum microwave radio systems are among the most interference tolerant communication networks in use today. Spread spectrum signals are very difficult to detect and, by their nature, are highly resistant to jamming and interference.

How it works - The "How To" of Satellite Communications. Satellite Communications Magazine

Handheld Satellite /Cellphone from Global Star - In brief article on Globalstar and the Qualcomm handset. (812kB PDF Format) - Nuts and volts Magazine

Hidden Sounds on your telephone line.

A world without wires

Mobile Radio Technology Magazine - An interesting magazine covering Mobile Radio and associated Technology. Some good technical articles in 'Techspeak' sections of back dated versions.
- The finer point of re-banding
- Measuring 800MHz interference
- Demystifying RF attenuators
- Ensuring RF is a multi-faceted task
- Site noise vs. system noise figure - No matter how good the noise figure of individual components of a receiving system may be, it is the overall system noise figure that represents the...
- Co-channel interference: How bad is it? - As the land mobile radio frequency spectrum has become overcrowded, interference has become the rule, rather than the exception.
- Optimizing Performance and maximizing capacity in CDMA systems - Several techniques can improve the performance and capacity of CDMA systems. RF engineers now realize that CDMA offers and opportunity to trade off capacity,...
- High-performance antenna design
- Intermod: Getting the upper hand (Part 1)
- Intermod: Getting the upper hand (Part 2)
- Getting back to basics: Filter terminology - PDF Version - Filters are indispensable in radio communications systems. Receivers and transmitters use them in RF stages, intermediate frequency stages and audio frequency stages. Much of the basic filter terminology applies to all types of filters used in receivers, transmitters, multicouplers, combiners and antenna systems.
- Using and converting RF units of measure - Many RF measuring units, as well as various forms of those measuring units, are in use today.
- Microwave path design - The Basics - This series of four articles is a primer on some of the propagation-related basics of microwave path design. - Part 4, Part 3, Part 2, Part 1
- Reduce noise in distributed communications systems - Back-end design fixes cannot improve a bad "noise lunch" at the radio system input, but tower -mounted amplifiers can improve overall system noise figure.
- Transmitter noise/ receiver desense primer When locating multiple stations at a single site, several precautions must be taken to guard against interference to all stations at the site. Among factors to be considered are transmitter noise and receiver desensitization.
- Tower-top amplifiers and noise figure (Part 1 of 2) - Part 2 of 2
- Tower-top amplifiers and noise figure
- Testing Tower Top Amplifiers (TTA) - The proliferation of the cellular telephones, PCS telephones, low power two-way radios, and wireless LANs, has created a need for tower top amplifiers (TTA)
- Ready, set, calculate - Erlangs? Queuing? Grade of service? Once you know the basics, you can use software to analyze trunked system capacity. Follow these steps to practical capacity planning for your radio system.
- Feed design and selection for microwave antennas
- Computer analysis of intermod requires a pragmatic approach -A prescription for an effective computer program to calculate intermod includes practical and user-friendly techniques for entering and analyzing data.
- Is your two-way radio system balanced? - The base station noise floor, vehicle noise and ambient noise in the service area can all contribute to throwing a radio system out of balance. Here's how to fix it.
- Why we can't talk? - It's the interference - Interference from wireless telephone base station antennas in public safety communications. The FCC has the power to prevent the interference.
- Does the digital radio standard come up short? - Computer modeling reveals why many coverage predictions do not agree with real world performance. When designing digital systems, engineers overlook the importance of carrier-to-noise ratios at their peril.
- Unlicensed microwave: Blessing or curse? Engineering discipline and rigor should be applied to system planning and design to use unlicensed ISM band equipment to its best advantage.
- Predicting Radio Channel Capacity - This article discusses how the capacity of a conventional two-way radio channel can be predicted by using a model that compares the behavior of human users on conventional voice channels to that of packets in a data transmission. Comparisons to the efficiencies in a trunked radio system are also discussed.
- Understanding Wireless Communications in Public Safety. Concluding excerpts from a guidebook to technology, issues, planning and management for public safety communications professionals.
- RF samplers and Directional Couplers
- Voice over IP: The next generation - Transmitting voice traffic over Internet Protocol offers a cost effective way to enhance existing communications operations without adding extensive infrastructure.
- What you should know about reframing - What do the reframing orders really mean, and how do they affect your decision to use centralized or decentralized UHF trunking.
- Transmission line measurements
- Antenna system troubleshooting simplified
- SWR, impedance and line loss - Standing waves on a transmission line affects both the impedance seen at the input and the overall loss of the transmission line the higher the SWR, the greater the effect on these parameters
- Data above voice systems - In the last 20 years, long-haul transmission networks were upgraded to transport digital signals due to the huge growth of the information
- Technical techniques: A primer for transmission lines Part 1 , Part 2
- Antenna system troubleshooting simplified - What is the quick est and most efficient way to determine the root cause of a failed transmission system?

Tower Mounted Amplifiers - Diagnostics and Isolations Measurements - How to use a Anritsu Sitemaster S251C to test TMAs.

Microwaves and RF Magazine - Articles from Microwaves and RF Magazine
- Filtering Interference From Cellular Receivers - Band-reject filters can be applied quite effectively in reducing or removing unwanted IMD interference signals from the operating band of a cellular receiver system.
- Filtering compromises from Co-located Systems - The cocktail of co-located spectrum and cell-based wireless services is leading to interference issues that can severely impact network performance, although custom co-location RF filters offer a practical solution.

TMA CDMA Coverage - A mathematical explanation of the benefits of using Tower Mounted Amplifiers (TMAs) in a CDMA system - Base Station Earth Station Magazine.

IEEE Spectrum magazine
- Cellular Security: Better, but foes still lurk - Service providers have largely solved the cloning problem, but eavesdropping is still an issue, and e-commerce has barely been addressed.
- Satellites free the mobile phone - The moment of truth is near for a number of ambitious satellite ventures designed to enable users of handheld wireless phones to communicate with one another from any two points on earth.
- Bluetooth's slow dawn - Hype gives way to hard work as expectations for the mini radio network encounter nettlesome interoperability issues. Contains a good simple explanation of specifications, and basic operation.
- A cell phone for all standards - Software running on general purpose hardware means not having to throw away your cellphone when standards change.
- The mobile phone meets the internet. Fifteen years ago mobile telephones were an exotic extravagance. Today, as cellular phones, they are often given away as freebies in support of marketing schemes and product promotions.
- Cell phones, Radars, and Health - Exposure standards for electromagnetic radiation do not adequately address current realities
- Radio interfaces make the difference in 3G cellular systems. More service providers opt for wideband code-division multiple access for the radio interface, but time-division multiple access is not dead yet.
- How does it sound? - To check voice quality, designers of compressed and packetized networks are enlisting computer-based techniques.
- Personal Locator services emerge.
- Designing a positioning system for finding things and people indoors.
- X marks the spot, maybe

Wireless Systems Design Magazine - For designers of Communications and computer systems
- The Design Challenges Of A 3G Video Cell Phone - Next-generation cell-phone design requires a strategy to optimize the quality of video and pictures sent over a 2.5G or 3 G network.
- Cancel Multipath In Spread-Spectrum Communications- An innovative cancellation approach can effectively migrate multipath problems with delays ranging from one chip period to multiple symbol periods.
- What's Up With 3G These Days? - Third generation technology promises ample benefits. Unfortunately, it also poses many challenges. Learn which new developments will help ease this growing design burden.
- Get The Signal Loud And Clear - Will tomorrows antennas provide the performance, range, and capability the wireless community demands at a price that they can afford?
- Can Bluetooth And 802.11b Co-Exist?- Carving out space for wireless communications based on established standards in the crowded 2.4 GHZ ISM band might be more difficult than first thought.
- Bluetooth Technology Integration: Which Path Should You Choose? - Flexible system architectures are critical for integrating bluetooth technologies, since design requirements determine what is right for an given device.
- TMAs Alleviate Cellular Network Strain - Although they offer cost and performance benefits, tower-mounted amplifiers must still prove themselves against interference.

Communications Systems Design Magazine
- Suppressing Errors in WCDMA Mobile Devices - As the final specs for WCDMA near completion, handset designs offering wireless Internet access with voice and data capabilities are close behind. But to make these products a reality, designers must first get a grip on minimizing BER in the RF front end.

Technology Review Magazine
- The Universal Cell Phone - software-based technology developed by the U.S. military could slice through the maze of conflicting standards and make it possible to use wireless devices anywhere, anytime-even downloading all the latest features as they appear on the market.

Microwaves and RF Magazine
- Comparing Infrared And Bluetooth Short-Range Solutions - Bluetooth and infrared short-range communications technologies can work well together when targeted to specific applications.
- Clarify Antenna Gain for Accurate Mobile Measurements - Understanding the true meaning of "Antenna gain" can help improve the accuracy of handset measurements.

Ericsson White papers - A collection of technical white papers from Ericsson.
- Publications

Telephony Online Whitepapers
- Can multicarrier PAs resurrect old cell-site assests? - Multicarrier power amplifiers (MCPAs) claim much in terms of flexibility, adaptability, and the range of applications in which they can be employed. Is all this hype justified, especially from a technology with its roots in a 1920s patent?
- Pico Cells, Femto Cells, and DAS - Spurred by new products from vendors such as ipaccess, Ubiquisys, 3Way, and Motorola, the marketplace has shown growing interest in pico and femto cells as a solution for in-building wireless connectivity.
- Evaluating Noise - What "noise" means in a cellualy system depends on whomm you're talking to.

CDG Whitepapers - A seelction of whitepapers on 3G CDMA2000 and CDMA Technology

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