Introduction

As human beings, we accept without question that we have the ability to communicate,
that if we speak or write according to a pre-defined set of linguistic
rules that we will succeed in conveying information to one another.The tools of
human communication, producing sounds that are perceived as speech or creating
words on a page, once learnt are used without thought.The limitation on these
physical processes that we take for granted is the actual translation of thoughts
into effective and meaningful statements.When it comes to electronic communication,
however, there is very little that can be assumed or taken for granted.
Communication between electronic devices can only be achieved when they also
abide by a set of predetermined rules and standards—the Open Systems
Interconnect (OSI) model for communications systems protocol stacks being the
primary example, and the basis from which many others have evolved.
These standards need to be applied to every aspect of the communication
process, from the manipulation of data at the highest level to the utilization of
physical transmission media at the lowest. Electronic communication has evolved
significantly over the last decade from the earliest packet switched data networks
(PSDNs) and the Xerox, Ethernet, and IBM Token Ring local area network
(LAN) technologies, to the now common-place mobile telephony and dedicated
high-speed data communication. (How would we survive without e-mail and
the WWW?)
New technologies are now emerging that allow wireless communication.The
IEEE 802.11b or Wi-Fi standard is becoming accepted as the choice for the networking
community as it supports features that enable it to perform handovers
between access points, and it can effectively become a transparent wireless network,
expanding the static wired network. IEEE 802.11b has a data throughput
of up to 11 Mbps, which gives it viability against wired networks.This is evolving
further with the advent of IEEE 802.11a and its competitor HyperLAN2 with
even greater data rates.This technology is expensive and therefore not compatible
with price-conscious consumer products, but we have now been provided with
the means to create wireless, low-power, cost-effective, unconscious and ad-hoc
connectivity between our devices. Its name: Bluetooth. If we believe all of the
hype surrounding Bluetooth technology, we can expect our fridge to use our
mobile phone to order groceries over the Internet, and, of course, end up
ordering an extremely expensive new car instead of a steak! Yes, we have all seen
the jokes, but in reality we can utilize this technology now to develop products
that will allow us to throw away all the wires—and communicate without cables.
Excellent, we all think, and our imagination races into the realms of Science
Fiction, removing the wires from everything! Musing on using our mobile phone
to communicate and control everything the same way we use the TV remote to
operate our entertainment systems.
This is a book for engineers in the real world, so let’s take a long hard look
at what Bluetooth technology really does offer. For some applications, Bluetooth
technology delivers the dream of convenient wireless connectivity. For other
applications, however, it just isn’t the right answer.You do not want to spend a
lot of time and effort learning about Bluetooth technology only to realize it isn’t
for you, so we are going to start out by analyzing what the features of a really
good Bluetooth product are. If your application does not fit into the Bluetooth
scheme of things, you can put the book down after this chapter and go and look
elsewhere.
If you make it past this chapter, you can be confident Bluetooth technology is
right for you.There will still be quite a few make or break pitfalls before you
have a killer application, but they are minor issues compared to choosing the
wrong technology.
What you need to know before reading this chapter:
 There are no pre-requisites for this chapter, though a broad familiarity
with communications products will be useful.
Why Throw Away Wires?
Wired or wireless? Let’s examine just why we’d want to connect without wires,
and what it might offer us in tangible terms; we can use the paradigm of our
own personal area network (PAN).We have a PC with its ubiquitous mouse and
keyboard, a laptop, a personal digital assistant (PDA), a mobile phone with a
“hands free” kit and a printer. How do we currently communicate between these
devices? The answer is: with a rather unwieldy network of cables, hubs, and connectors—
plugging, unplugging, and synchronizing often with the compulsory
intervention of the overworked and often less-than-friendly IT department!
In the wired solution scenario that we are all accustomed to, all of the mobile
devices are used in the singular—the interaction between them is always userinitiated.
We generally keep our contacts’ addresses in our PCs or laptops, while
their phone numbers also need to be entered into our mobile phone’s directory.
We are effectively forced to become database managers simply in order to maintain
an up-to-date record of our contact’s details.We connect to our company
LAN via user-initiated password entry and connect to a printer only if we have
already installed the driver or have administrator rights on our PC’s—nothing is
unconscious.
Figure 1.1 illustrates the alternative scenario—to Bluetooth-enable all of these
devices.The simple act of utilizing Bluetooth technology as cable replacement
removes the problem of the actual physical connections and the unconscious and
ad-hoc connection capability of the technology can allow communication
between the devices with no user intervention at all (OK, after some software
configuration and initial device setup!).
This fully wireless scenario can be achieved because of the master/slave nature
of the Bluetooth technology. All devices are peers, identified by their own unique
48-bit address, and can be assigned as a master either by function or user intervention.
A master can connect to up to seven slaves at the same time, forming a
piconet—this “point-to-multipoint” feature is what sets Bluetooth apart from other
wireless technologies. Figure 1.2 illustrates several connection scenarios.
Figure 1.1 A Bluetooth PAN (Doesn’t Include Power Cables to PC
and Printer)
Headset
Cellular
Phone
PDA
Laptop
Mouse
Printer
In the ultimate scenario, a member of one piconet can also belong to another
piconet. Figure 1.3 illustrates the scatternet, wherein a slave in one piconet is also
the master of a second piconet—thus extending the networking between devices.
A device in my PAN can communicate with one in yours!
Let us put this into context by interpreting exactly what “unconscious and
ad-hoc connections” can mean to us in real life, and how the fundamental components
of the Bluetooth PAN in Figure 1.1 can be integrated into a wireless
infrastructure to enhance our lives and even reduce the need to queue!
Adding Usability to Products
Mr. I.M.Wireless is embarking on a business trip. At the airport, as he gets
within range of the airline’s counter, his reservation is confirmed and a message
is sent to his mobile phone detailing flight confirmation, personal boarding reference,
seat information and departure gate number, which he listens to via a
headset being that his phone is actually in his briefcase.While in the departure
lounge, he connects to the Internet and accesses his e-mail via his mobile
phone or the wireless LAN Access Point fitted in the lounge. He boards his
flight and during the journey composes e-mails which will be sent as he enters
the range of a LAN in the arrivals lounge or again via his mobile phone. He
walks to the rental car company’s counter to pick up his keys—as with the airline,
all booking, payment, and car location details would have been transmitted
between his PDA/mobile telephone and the rental company’s computer. He
starts to drive the rental car and his PDA downloads his hotel information into
the car’s on-board systems, which allows the navigation system to smoothly
direct him to its location. On arrival, his room booking reservation is already
confirmed. At his meeting, the normal 15-minute exchange of business cards is
removed as all of the personal information is exchanged automatically via his
PDA. He then uses his PDA to run his presentation from his laptop, which all
attendees at the meeting are viewing simultaneously on their own laptops. Back
in his hotel room after the meeting, his PDA synchronizes with both his laptop
and mobile phone—now the telephone details of all the new contacts he met
are stored in his mobile phone directory and the address and e-mail information
in his laptop. Later, while relaxing, he listens to MP3 files stored on his
laptop with the same headset that he answers his phone with. He also uses his
digital camera to send “an instant postcard” via his mobile phone and the
Internet to his wife’s PC at home (obviously, it won’t be a picture from the
Karaoke evening arranged by his clients!)
If we extract some conclusions from this slightly excessive example, we find
that wireless connectivity offers us immense freedom and convenience. It allows
us to perform tedious tasks with a minimum of intervention, allows some of our
devices to have dual functionality, and makes the vast array of cables we inevitably
always leave in the office redundant. Bluetooth technology “will” change the
assumptions we all have about our electronic devices.With the cables gone, the
idea of having a particular gadget for a specific job will no longer be relevant.
With many of the devices already available to consumers, this scenario grows
closer to reality every day.