Wireless Systems Design

Guarantee The Success Of Future 3G Handsets

To Obtain GPRS/UMTS Terminals That Succeed Technically And Make A Profit, Six Requirements Must Be Met.

Interactive content could lead companies out of the current UMTS predicament. According to research conducted by Forrester Research, consumers in Europe spent some 101 billion Euros on communication via fixed network, mobile phone, and post in 1999. The research also uncovered an interesting fact: New interactively assisted content could produce a host of successful services. Frost & Sullivan ascribe a further lion's share of the revenue to mobile gaming. By 2008, it predicts that 178.8 million mobile gamesters will exist.

Interactive content places highly complex requirements on mobile systems. It involves a combination of flexibility and wide-ranging functionality with minimal memory size, processor, and battery power. Memory protection also is part of the mix. Hardware restrictions have to be offset by means of intelligent software. As a result, the profitable development of mobile communications systems calls for fundamental importance to be assigned to six main requirements.

Before delving into the six requirements, it's important to note that ensuring cost-efficient production can be difficult. Over the long term, however, it does safeguard investments in development. The use of a common basic platform for differing handset models presents an ideal solution (FIG. 1). In the 3G handset, for example, the hardware and software platform will become like the chassis of a car. The same chassis can be used for several types of car models.

In this way, 3G-handset applications can be compared to the features of a car, such as air conditioning, electric moon roof, dual air bags, etc. The 3G mobile phones that are built on one general platform will host different and varying applications. The handset manufacturer will differentiate the devices so that they range from low-end to high-end. That manufacturer will also design handsets for different user profiles.

A 3G platform cannot be exactly the same for all types of terminals. For example, the memory configurations and possibly the CPU extensions are different when comparing a voice-only mobile telephone and a multimedia terminal. For various applications, however, the basic design and architectural versions can be used more than once. A significant potential for savings can be gained by reusing the system software in the various hardware configurations. Such software includes telephone protocols, baseband software, a call control system, and voice coding and decoding.

In general, six requirements exist that must be met in order to obtain successful GPRS/UMTS terminals. These requirements assume the use of a common basic platform. They comprise the following:

Dynamic Program Loading In Real Time
A key feature of 3G is the ability to update the software inside the telephone at any time. This aspect gives manufacturers and end users higher flexibility. The hardware and operating-system platform must therefore support the dynamic loading and unloading of programs in run time (FIG. 2). In addition, the handset must be upgradable at any type of usage by equipping it with different applications. The manufacturer can then update software with new versions at a very late stage in the production cycle—or even after the unit is shipped. For the user, this translates into the ability to get a new phone simply by purchasing new applications to add to the existing factory-installed capabilities. Subsequently, the user's handset can be turned into anything: a phone, a PDA, or perhaps even something not yet imagined. Business-to-business applications also are sure to appear on the market.

Cost Efficient Use Of Memory
Saving memory is probably the most significant cost-saving factor for a 3G handset. To compensate for limited memory, more demand is placed on the handset software. This is particularly true for the platform software. As a result, the operating system itself must be compact, modular, and highly configurable. It should consist of several modules that can be included or excluded, depending on the required functionality.

For example, in the OSE for Wireless Devices operating system, each component's footprint (code only, no data) ranges from 60 to 150 kB. An extensive choice of modules usually results in a system of approximately 700 kB. Each component should offer several configuration options that can scale the component up or down in both functionality and size. The operating system also must consume as little RAM as possible when executing. It can achieve this goal by limiting the use of buffering and advanced memory management, including efficient methods of preventing memory fragmentation. If all operating-system components are able to execute out of either RAM or Flash, costly RAM is saved.

Another mechanism that saves space is shared libraries. This approach allows several applications to run the same code with different data. When implementing shared libraries, keeping the real-time characteristics of an RTOS can become a somewhat complicated process. But in OSE for Wireless Devices, shared libraries can be used without the typical traditional shortcomings, such as longer interrupt latency.

Transparency In Distributed Systems
A 3G terminal is a good example of a typical multiprocessor design in which application programs can run more efficiently. To attain this efficiency, the processor operations are distributed over CPUs and DSPs. With one standardized RTOS that supports both general-purpose CPUs and DSPs, the software can be used repeatedly in different hardware configurations. The same system software, like telephone protocols, works with one or the other microprocessor on both the CPU and DSP at the same time. Or, it works on one DSP. If the RTOS offers a common application programming interface (API) and transparent communication over CPUs, the CPU boundaries become invisible. Applications can then be easily moved from one CPU to another with little to no changes required (FIG. 3).

Reliable And Robust Service
What is the "killer application" for 3G handsets? As with 2G mobile phones, voice communication will most likely take top billing. In order for it to succeed, however, the reliability of the phone call must be outstanding. It must rarely fail to connect. It also has to connect quickly. In addition, it must almost never disconnect spontaneously.

Several ways exist to ensure a robust system. Error handling in the RTOS kernel, for example, enables the isolation of errors and their handling. In OSE, calls do not return error codes. Instead, whenever returning from a system call, the application understands that the call was successfully performed. If the call fails, control is transferred to an error handler with an error code for identification. The error handler can then take appropriate action. It might, for example, perform another system call, inform another application of the problem, or restart an application (FIG. 4).

On a single CPU, the OSE mechanism's supervision of tasks, programs, applications, and entire units is very useful. In a distributed environment, however, it is essential. Application A can request supervision from any other application B. If the supervised application B is for some reason not available, A will get an automatic notification. Then, A can take an appropriate action. It may, for instance, redirect its communication to C. The OSE for Wireless Devices OS provides a mechanism called hunting for an application. Issuing a hunt request causes the kernel to send the identification number (task ID) of the application's name as soon as the application is available.

Memory protection shields the system from crashes due to memory violations. The handset will have certain software, such as telephony protocols, that simply must not crash. Because a 3G handset will have many more applications than today's phones, it is inherently more vulnerable. It is simply unacceptable for faulty applications to crash other applications or even the system itself.

In the next-generation handsets, system software will put very high demands on reliability. It will be forced to co-exist with less critical software, such as games. Applications downloaded in run time also can be memory protected. Perhaps more importantly, the system can be protected from downloaded applications. For these reasons, products like the OSE operating system integrate a memory manager and protection software with run-time loading functionality.

Combined Memory Model
Great care has to be taken when selecting the memory-management facility for a mobile terminal. The combination of three different memory-addressing methods provides an efficient solution. These methods include Single Address Space Equal (SASE), Single Address Space (SAS), and Multiple Address Space (MAS).

Of the three methods specified, the MAS method is the newest. This technology is used for virtual memory systems in most desktop OSs, such as Solaris, Linux, and NT. But in a real-time system that requires high processor performance with the minimum amount of space, MAS presents a number of disadvantages. Consequently, combining SASE, SAS, and MAS invites a host of advantages. Each memory-addressing method presents advantages for different code and data types. MAS is only used in areas that actually require it. This approach accelerates execution while offering real-time behavior.

Minimum Power Consumption
A long standby and operating time rank among the main factors that will ensure the success of mobile terminals. In spite of their minimum power demand, CPUs and DSPs should be operated at the lowest possible frequency whenever possible. The mobile applications also should reduce power usage. When possible, savings should permit applications to be powered down. In addition, the power of all modules should be reduced whenever they are not directly required.

I/O modules could, for example, be powered down. The processor could then switch to a power-saving mode. In most cases, however, a power down entails using up further time and power. Accordingly, powering down a module does not always present the best solution. Consequently, the user program should be capable of determining the modules for which this activity makes sense. Subsequently, it should be able to figure out the time for which each module must be powered down in order to achieve effective power savings.

The power-management facility of OSE for Wireless Devices permits this type of intelligent decision with the aid of an additional halt feature. If specific conditions have been met, the module switches to a power-saving mode.

Following the six criteria that are described in detail above will allow 3G handset manufacturers to obtain successful GPRS/UMTS terminals. Com-bining the criteria with advanced applications gives a profitable and compelling handset product. OSE Systems' collaborations with Synergenix for mobile gaming and with 3GLAB for mobile branding are examples of this. OSE Systems and Synergenix recently introduced the Mophun game engine for OSE for Wireless Devices.

Manufacturers can now build robust and power-efficient mobile devices with advanced gaming. For the end user, that means access to enjoyable mobile gaming that is similar in quality to gaming consoles. The graphics-rich, real-time interactive games can be downloaded directly from the Internet or over the air. The Mophun gaming platform, for example, runs on extremely limited hardware resources. It boasts a minimum requirement of an 8-b processor running on 12 MHz (FIG. 5).

Consumers are increasingly demanding mobile phones with advanced multimedia capabilities. At the same time, network operators are looking to bring to market high-quality, own-branded devices that enable the delivery of advanced services. The pre-integration of 3GLAB's Trigenix mobile interface software and OSE's real-time operating system provides engineers with a pre-validated dynamic software solution. This solution is based on the core ARM architecture. OSE's run-time program loading provides the dynamic functional updates. Meanwhile, Trigenix's over-the-air customizable user interface provides ease of use. It enables the rapid development of mobile phones with user interfaces that can be fully branded and "themed" to meet operator market needs (FIG. 6).

For more information on the topic discussed, please refer to the references listed here:

  • www.ose-systems.de

Here you will find a white paper on the OSE wireless platform, as well as detailed information on the development of third-generation handsets.

  • www.powerrankings.forrester.com/ ER/Research/Report/Summary/0,1338,14551,FF.html

Go to this site to download a copy of the Forrester study entitled, "Conversational Content Unlocks Revenue."

  • www.frost.com/prod/servlet/fcom? ActionName=DisplayReport&id=7914-01-00-00-00&ed=1&fcmseq=1030477355169

At this site, you can check out the studies of mobile gaming that were conducted by Frost & Sullivan.

  • www.strategyanalytics.com/cgi-bin/greports.cgi?rid=142002070631

This Web site features a market report on the topic of mobile phones with Digicam.

TAGS: Mobile
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