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Examples of Usage Models
Because the specific profiles define the least common denominator for different Bluetooth units, most devices will support several profiles. Here are some examples of such usage models, but for a complete description, please refer to the Bluetooth specification.
Profiles: Dial-up networking profile, fax profile, LAN access profile, SPP
The divided concept, described more in detail in Chapter 10, “Mobile Internet Devices,” describes how many users will use the phone as a modem and then
use a laptop or PDA for the applications. Bluetooth is an excellent facilitator of this usage model, and the Bluetooth -enabled phone then acts as an Internet bridge. The phone should then have both Bluetooth and GPRS/3G functionality (using the Bluetooth connectivity between the phone and PDA/laptop). This process requires a two-piece protocol stack—one for the actual data and one for AT commands that can control the mobile phone (like a modem, in this case).
The Ultimate Headset
Profiles: Headset profile, SPP
The Ultimate Headset describes how a Bluetooth headset can be used to not only send and receive voice packets, but also to command the phone to (for instance) answer and terminate calls. As with the Internet bridge, this functionality requires a two-piece protocol stack: one for the actual data and one for AT commands that can control the mobile phone. Note that unlike regular mobile phone headsets, a Bluetooth headset can be used with phones from multiple vendors and also with PDAs and laptop computers.
Profile Example in Existing Bluetooth Products
When you specify the capabilities of Bluetooth products, you will likely use the profiles. The official Bluetooth Web site, www.bluetooth.com, lists the latest-released products in a number of categories. Toshiba released its first version of an Internet bridge called a Bluetooth Modem Station. The description is as follows:
Toshiba Bluetooth Wireless Modem Station PROFILES:
Generic access profile Serial port profile Dial-up networking profile Fax profile
Compare this description to the previous section, and you will find that the description is similar to the Internet bridge usage model. Another example is a PC card from Digianswer:
Digianswer Bluetooth PC Card PROFILES:
Generic access profile
Service discovery application profile
Serial port profile Dial-up networking profile Fax profile LAN access profile Object push profile File transfer profile
The PC card consequently is a much more versatile device and is expected to interact with many different kinds of Bluetooth units. The Bluetooth home page is a good source for information about the compliance of released Bluetooth units that can be very helpful when designing applications around them.
The Applications and User Interfaces
We often use the word ‘‘application” in many different contexts and for different things, as mentioned in Chapter 1, “Basic Concepts.” Throughout this book, we talk about software applications and services—but for Bluetooth, there will be many combined hardware/software products that are of great importance. Because there were initially no Bluetooth -enabled devices for developers to play with, the first wave of applications will be of the hardware/software kind (and often standalone applications). As more and more Bluetooth devices appear (and some even with open platforms, such as Communicators), the software can enter the scene on a wide scale and provide a wide range of interesting applications. Bluetooth is one of those technologies that opens up such interesting possibilities that even its creators have no idea what the innovators will come up with as uses for it.
The first Bluetooth implementations are likely to focus on point-to-point communication, such as a wireless headset for mobile phones, PC cards for laptops that can access the Internet through Bluetooth-enabled mobile phones, and so on.
An important question is how Bluetooth will look and feel for the user. We do not mean the radio waves; rather, we are talking about the Man-Machine Interface (MMI) for devices. This issue is really two-fold in the sense that you have one interaction when new devices and services are discovered and one when the service is being used. We describe a few user models and the MMI in the following paragraphs.
Headset MMI Example
When a headset is to be used with a mobile phone, the two units need to discover each other and become paired. The following procedure outlines a common way of performing this task (used by the Ericsson Bluetooth headset).
1. The button on the headset is pressed for 10 seconds so that the light starts blinking red and green. This means that it is ready to get paired.
2. On the phone, the Bluetooth menu alternative is selected, and you can then select to pair the phone with another device.
3. You are then asked to prepare the other unit (here, the headset) and press a button to start the discovery process.