Sasken > Downloads : Times Global Journal

Mahesh Kolar is General Manager - Product Design at Sasken Communication Technologies Ltd. He currently manages the Product Design Portfolio for Handset Solutions Group primarily for wireless devices (mobile phones / POS terminals, GPS loggers, hand-held devices etc.) with a mandate to grow the product design business out of Sasken India, China and Finland for global markets. In his current role, he is working with customers to help with their design needs, either by way of product re-engineering or NPI (new product introduction).

MAHESH KOLAR while highlighting the importance of sophisticated computing performances and improved battery life in next-generation handsets and cell phones explains the various technologies that will impact the design and development of new wireless devices… Next generation handsets now mean having devices with advanced computing performance and decent battery life. These devices will need to handle applications beyond plain voice, SMS, ringtone/game downloads etc. and need to cater to requirements such as multimedia streaming, video downloads and TV broadcasts as well. These call for powerful devices with sophisticated computing performance and good battery life. Mobile devices will have to have high processing speeds, large RAM memories, high resolution wide displays and large storage capacities.Let us briefly examine some of the technologies impacting the design of new wireless devices.

BASEBAND PROCESSORS The field of baseband processors is beginning to see a shift in the market share currently retained by some of the major players. Market leader Texas Instruments perceived to have lost some market share in this space has challenging times ahead to rebound and maintain its competitive position. With new wireless standards under development, the baseband market is up for grabs. The focus is now on having a 45 nanometer product line

APPLICATION PROCESSORS Application processors typically have the ability to run different type of high data rate applications that include multimedia apps as well. ARM architecture dominates in this space with the majority of the market share (about 90%) that includes ARM 7, ARM 9 and ARM 11 chiefly. ARM 11 has some major advantages over previous versions:

The most supported operating systems (OS) by CPU manufacturers tend to be typically Symbian, Microsoft, Palm and Linux as these are considered to be the dominant players in the market for smartphones and hand-held computers. Applications supported by RTOS are generally handled by use of hardware accelerators embedded in the modem.

DISPLAY TECHNOLOGIESLow-end mobile devices continue to ship with monochrome (black & white) displays; this trend is expected to decline over the next couple of years and these displays may even disappear from the market by 2010. With the availability of 2.5G and 3G services, high resolution color displays became necessary to support applications such as camera, Internet browsing, image viewing etc. Till recently, 4K (4096) colors were the most supported depth and this is now expected to be overtaken by 65K. Handset designers need to factor the basic challenge of power consumption when using color displays in their design - this is one area where the display product can be differentiated by providing color displays with high energy and low resolution. Mobile handset makers currently deploy in excess of 150 types of screen resolutions with varying pixel count and supporting more than 50 screen sizes. Some items of note with respect to display technologies currently being used and the future trends are outlined below:

TYPES OF DISPLAY TECHNOLOGIES: LCD Technologies Mobile computing devices are now displaying a trend towards supporting increased functionality and performance. This trend is resulting in display manufacturers working on screens that display additional information content with visual performance with reduced power consumption and cost. LCD displays are usually hard to decipher in low light conditions or at night; these issues are being overcome by LCD vendors by incorporating thin film passive structures in the LCD screens to facilitate the reflection and transmission of light, overcoming viewing constraints and resulting in improved battery life. Polymer-based Technology A promising new technology is the organic light-emitting diode (OLED). OLEDs work by using electric currents to stimulate certain organic molecules or polymers to emit light in a range of colors. OLED technology has the potential to be used in the handset market because of the benefits offered by way of high resolution and low power consumption. The development of OLED displays is expected to gradually improve over a period of time to when it might be actively considered for mass production and commercialisation.

Other Technologies Of interest here is active matrix display that combines electronic ink, color filtering arrays and active matrix techniques. This technology offers low-power consumption and reliable viewing in all lighting conditions but offers resolution only up to 4K color. Some latest handset models (clamshells and sliding bar devices feature two screens - this is usually achieved by having the main screen with high resolution and fast response time (for new applications and services such as viewing pictures and gaming) while the second screen usually displays the clock or caller ID. Imaging Technologies Most handsets today feature an embedded camera module. Initial devices featured complementary metal-oxide semiconductor (CMOS) image sensors with more emphasis on low-power consumption at the expense of image quality. Another technology is the charge-coupled device (CCD).

An evolutionary look at various types of batteries and power resources and their characteristic "product attributes":
Nickel Cadmium		Early type to be used in mobile handsets Mature and low cost. Used in low-end voice only devices. Contains toxic metals, making it environmentally unfriendly. Loses maximum energy capacity if repeatedly charged before being totally discharged.
Nickel metal hydride (NiMH)		Used in mobile phones and laptop computers. Competitive pricing makes it attractive for use in ultra-low-cost phones. Does not contain toxic metals. Does not suffer from memory effect.
Lithium Ion		Popularly used for mobile phone solution. Provide larger energy density. More expensive than other battery types.
Lithium Polymer		More reliable.Smaller in size and weight. Allows for shaping batteries to fit different devices. Offer higher capacity than lithium-ion batteries. Long charge times and slow discharge rates.
Fuel Cell		Increased reliability and low environmental impact. Recharged by the addition of more fuel.
Photovoltaic		Long time needed to recharge batteries. Use of solar energy to charge in bright sunlight.

CMOS sensors have advantages over CCD technology that include factors like cost, power and size. Unlike CCD modules that require extra chips to process and convert analog signals to digital form, CMOS sensors provide for easy integration allowing the combination of image sensing, digital logic and memory functions onto a single chip. CCD sensors, on the other hand offer smaller pixel density and pixel size compared with CMOS, which allows for higher resolution. Given that screen technology is in a continuous state of improvement and the proliferation of high bandwidth services, newer devices now tend to feature high resolution camera modules through the use of CCD sensors.

Low-end devices meanwhile continue to use CMOS technology to keep the power consumption and the cost of the device low. The fact remains that most consumers use the camera feature very sparingly due to image quality issues - this issue is now being addressed by considering increasing the number of pixels in camera phones among other things such as use of lens, filters, size of the image sensor, DSP and software used for image processing. Today's camera phones boast resolution in excess of 3 MP - it is expected that the competition between CMOS and CCD technologies will intensify allowing for CCD to gradually gain momentum and catch up with CMOS technology. Battery Technologies Typical considerations that mark the development of battery technologies for use in mobile phones are:

Smaller weight
Smaller size
Improved power capacity
Reliable performance
Reduced charging time
Low cost

Smart packaging to allow for fitment to various mobile handset form factors. Today's mobile applications such as Internet browsing, multimedia streaming, interactive games or mobile TV call for power-hungry hardware and software components in order to deliver on good performance. Device manufacturers are now working on improving their products by using lower power consumption modules and components. New power resources such as fuel cell, lithium polymer, solar chargers or disposable batteries also have potential to challenge existing technologies by improving battery capacity and having reduced size and weight.