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GPRS and 3G Wireless application - Anderson C.

Anderson C. GPRS and 3G Wireless application - Wiley publishing , 2001. - 356 p.
ISBN: 0-471-41405 -0
Download (direct link): gprsand3gwirelessapplica2001.pdf
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One important aspect of the operatorís involvement is that the device must not limit the choice of business model. The operatorís portal and service network components must be configurable and given a prominent placing. This process requires many options to be configurable, which in turn can potentially make the device less user friendly. Many users will get their first mobile Internet device after only using a cellular telephone, where they did not have to do anything more than dial the number and press the dial button. You cannot expect those users to pull up the configuration menu and choose what WAP gateway to use. One solution is Over-the-Air (OTA) configuration, where a message (usually an SMS) that contains the settings is sent to the phone from the operator. The phone then interprets this message and automatically configures the device accordingly. Nokia and Ericsson phones support this feature, but there is no standard available.
The Man-Machine Interface
Even if advances in battery and display technology result in larger displays with color support and a higher refresh rate, the size of those displays will still be limited for the majority of devices. For hand-held devices, the name indicates that users are not likely to want devices that are significantly larger than todayís PDAs. The task for device manufacturers is instead to get as much display from the limited form factor without sacrificing battery life. The display of a color PDA stands for a large part of the total battery consumption, and a larger display means a shorter battery life. Another factor that limits the display size is also the robustness of the device. A large screen is more sensitive than a small one. I have dropped my phone on the floor many times without any problems, while my PDA broke the first time that I dropped it on the floor from a distance of one meter.
By saying Man-Machine Interface (MMI) we mean the way in which the device enables the user to interact with it. The MMI is constructed so that it enables the user to control the device in sufficient detail without making things too complicated. Typically, the MMI makes choices by asking the user questions, which removes some of the details that are likely to cause confusion. For example, a user might want to connect his or her laptop to a General Packet Radio Services (GPRS) network via a GPRS-enabled PC card. The modem software on the laptop then gives the user easy access to the network card, and one
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click on an icon initiates the connection. In the background, this action has Attached the GPRS user to the network, initiated a Packet Data Protocol (PDP) context activation, and obtained an IP address. A hand-held device also needs to provide this kind of abstraction.
The main challenge of designing the MMI is the large number of features that many devices now have. The R520, for example, has five bearers over which a connection can be made: GSM circuit-switched (HSCSD), SMS, infrared, GPRS, and Bluetooth. For future devices, you can add EDGE and WCDMA to that list. If the user then wants to use the WAP browser, how can the device know whether the user wants to use SMS, GPRS, WCDMA, or HSCSD in order to attach to a network server (or perhaps use WAP over Bluetooth to access an information kiosk that is nearby)? More than likely, the majority of users will not be able to (or want to) make these kinds of decisions.
One solution is to preconfigure a preferred bearer for each kind of service and then let this bearer be configurable through settings on the device. For sending business cards, it is likely that the preferred bearer is Bluetooth (or possibly infrared), while GPRS conveniently handles WAP. In this way, the MMI makes it easy for the user to get started with the device, but advanced users can still affect the configurations.
One of the great challenges of future devices is to handle the different Quality of Service (QoS) classes of (primarily) the 3G systems. With the different parameters of each QoS class, there will be tens of thousands of QoS combinations. If the operator then wants the users to pay different prices for different levels of QoS, things become tough. Some of the QoS settings will be available to the application through APIs (not yet specified). This point is where application developers will be even more closely involved with the mobile Internet value chain. Suddenly, the way in which the application selects these QoS parameters affects how much money the subscriber is charged. This situation cries out for a closer relationship between the involved parties.
Communication
In addition to the dilemma of knowing which bearer the user prefers, numerous other issues are connected to the design of wireless devices. Wireless standards are generally constructed so that the network can choose whether to support some features that can then be added later as a network is upgraded every once in a while. The terminals and the devices, on the other hand, must usually support a majority of the functionalities from the beginning. One example is the coding schemes for GPRS. As we described in Chapter 3, ďGPRS-Wireless Packet Data,Ē there are four coding schemes (CS1 -4) while some infrastructure vendors will only support CS-1 and CS-2 initially. Handset manufacturers, on the other hand, have to support all four coding schemes.
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