Electronic Design

The All-In-One, Do Everything Handset

Cell phones may be the perfect all-time electronic product. Worldwide sales topped 670 million in 2004. In 2005, we should see sales top 700 million phones, with China being the largest market with over 250 million units.

We love our cell phones. They get better each year while cost stays at a reasonable level. But it doesn't get any easier for the designers who continuously try to cram more features and gadgets into each new model. Color screens and built-in still cameras are virtually standard today, as are text messaging, games, and contemporary ring tones.

Special models like the BlackBerry and Treo with built-in push e-mail and PDAs are hotter than ever. Now there's a growing interest in push-to-talk (PTT) models, such as those pioneered by Nextel. Even worldwide satellite phones, including versions from Globalstar and Iridium, have made a big comeback despite their projected demise. What we have is cell-phone diversity with a cornucopia of features to satisfy everyone.

JUST DON'T CALL IT A CELL PHONE
The cell phone was originally designed as a... duh... wireless telephone. It has since morphed into a nearly indispensable, all-purpose tool. But it's becoming more than that. It's slowly but surely evolving into... ta da... a mobile entertainment product.

The so-called convergence movement seems to be happening first in the cell phone. Most manufacturers appear to be taking a multimedia design approach. You can already get an FM radio, MP3, or other music player in some phones.

Color screens were the first step toward the fully converged cell phone. Then along came still cameras. In forthcoming models, we'll soon begin to see some amazing additions. Several carriers are working toward video presentations including news and sports clips, music videos, and entertainment segments.

Too much video on a cell-phone network would no doubt bring it to its knees. Then why not just put a TV tuner in the cell phone and be done with it? Even though it doesn't seem to make sense to watch TV on a two-inch screen, there's no doubt that TV will be a popular feature. With single-chip tuners already available, it's a relatively easy next step to build that in.

Machine-to-machine (M2M) lets you monitor and control functions from your cell phone. You could check your home security system from anywhere. You could control the lights, thermostat, or appliances, or even link to a small video camera. You may even be able to call a special number to get traffic reports or monitor the video cams on a particular highway. M2M could become one of the most useful functions of all.

What else? How about a cell phone with built-in Wi-Fi? No, your cell phone won't replace your 802.11 link from your laptop to the hot spot. Instead, you will use the cell phone Wi-Fi connection for VoIP. If you lose your cell connection, you can always make your calls via any available hot spot. Or, use your cell phone as your main phone inside a facility that uses wireless access points. Maybe you don't want to stay all that much connected, but you can. Japan's NTT DoCoMo just announced its dual-mode cell phone with Wi-Fi. It's here now and will be even more available as a feature.

DESIGN CHALLENGES
Designers involved in cell-phone design already know the problems of trying to put all this stuff inside a tiny battery-powered handheld device. The key issues they face:

  • Power consumption: The more goodies you add, the more power it eats. This means restricting cell phones to a selected number of features, plus improving power management. The chip companies have made the battery last far longer than anyone ever expected. Hopefully, there's room for improvement.
  • Smaller size: You wouldn't think cell phones could get much smaller. People like small, cute, and cool. While space is limited, we have to make way for the new multimedia and other features.

The clamshell has also made designs tricky. With the color screen in the upper half and the remainder of the circuitry in the lower half, you need a large multiconductor bus to make all of the connections. Such buses become less viable as the multimedia features push bus speeds higher. One solution is a fast serial bus that can do the job between the two parts of the clam shell, and several vendors have already developed such buses.

  • New architectures: Some chip vendors offer new chip sets with architectures that eliminate the separate multimedia processor prevalent in today's designs. Many include MPEG-4 video compression, greatly reducing the data rate for quality video. This new architecture should help with the size and power-consumption problems. And, these mostly DSP-based phones can be more easily updated by downloads from the carrier.
  • Meeting the carrier's specs. Up until now, cell-phone manufacturers have decided what phones to offer, what features to include, and how they should look. It seems as though we're headed toward a period where the carriers will begin specifying phones they sell to better match the features they offer.
  • Security and worse: Security has always been an issue in any wireless application, some more critical than others. It's becoming an issue as the cell phone's modes of communications diversify. At some point, viruses, worms, and spam will become an issue. It's time to anticipate this issue and develop solutions that won't affect the cell-phone user as it has the PC user.
TAGS: Mobile
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