Both the value and convenience of wired networks is inversely proportional to the distance they cover. Few doubt the value of a very high bandwidth, worldwide network that provides a backbone for large volume voice and data transmission. Telecommunications and fiber providers linking this backbone to ISPs and individual companies are also providing high value and an essential service. Both of these services provide a "many-to-many" connection that more than justifies the cost of the wire infrastructure.
Local area networks (LANs) for individual businesses are a different story. The cost and inconvenience to wire a small or even medium-sized business is high, but generally considered worthwhile to provide connectivity among individual computer users, one or more network servers and the world outside the company.
The home is even more difficult. For example, home users are likely to have a number of different devices that may make sense to network together, but in the home there are typically fewer users than devices. The home user is also likely to be less willing to spend the money and time needed to wire a private residence to connect the TV set-top box, home theater, telephone, computer and other appliances together to the outside world.
An extension of the home is the individual. Today, the digital user may be carrying a PDA, cellular telephone, digital camera, and pager, plus have a GPS receiver and computer in the car. All of these devices are designed to provide services to the user, and to make everyday life simpler and more efficient.
But it's not that simple. The digital user of today spends too much time coordinating information between these various devices, and establishing communications links to gain a significant advantage in efficiency. For example, you may receive an e-mail on your cellular telephone, but really need the information contained in that e-mail on your PDA. You may also have to set an appointment on the calendar on your PDA based on a page from the pager.
It's not possible to manage these types of transactions easily. In many cases, they may not be possible at all. The user is stuck with data on one device that simply can't be moved elsewhere. At the same time, wireless networking technology is getting ready to move into the product mainstream. Packet-based wireless connections are well within existing technology. Wireless LANs based on Ethernet have been available for quite some time, and the price point has come down to the point where it's become feasible for common use.
It seems logical to tie together these two trends to use wireless, packet-based network technology to establish data communications channels between an increasing array of home and personal electronic devices. This approach can ease the convenience of personal devices for the individual, paving the way for the next digital revolution.
The answer to the dilemma of data exchange among personal digital devices is coming out of the IEEE 802.15 Working Group, which is defining the next-generation wireless personal-area network, or WPAN. WPAN can be viewed in terms of the other network structures available today: the wide-area network (WAN), the metropolitan-area network (MAN) and the local-area network (LAN).
WANs tend to interconnect large groups in different cities and even countries. Most international business enterprises have a WAN for internal communications. MANs, also known as campus-area networks, interconnect smaller groups in buildings in an office park, college campus or other contiguous locations. LANs, of course, connect individuals, usually at a single location or within a single company.
The WPAN scales down still further, to become, in effect, a personal network for a single individual, handling that individual's interactions with their digital devices. It provides the connection infrastructure between the various personal, home and office electronic systems that a person uses daily. It is aimed at addressing the problem of seamlessly getting information between those devices.
There are a number of potential technical issues with the specification of a personal network. In effect, since each WPAN device is a radio, there are problems with power management, radio frequencies, transmission ranges and bandwidths. Currently, existing and proposed wireless networking technologies operate in the unlicensed 2.4-GHz industrial, scientific and medical band.
In addition to the concerns of building products with integrated wireless networking, there are issues surrounding interference in wireless transmission. Many network protocols are designed to protect against packet loss through acknowledgement and retransmission, which works fine for some applications. That approach increases bandwidth requirements, however, which can reduce overall transmission rates. Depending on bandwidth availability, this may present problems for transmitting streaming media such as audio or video.
Interference problems can also occur if two such networks get too close to each other. To address that potential problem, it may become necessary to define the network so that the transmission packets identify each personal network uniquely.
Fortunately, teams of designers are working to solve the technical issues behind the design and implementation of WPAN networks and to standardize designs so that communications between them are seamless. The IEEE 802.15 Working Group was formed to develop media access controller (MAC) and physical (PHY) interface standards for short-distance, personal wireless networks to support personal, home and office mobile devices. About 50 companies are taking part in the development of the WPAN standard.
One of the group's goals is to achieve coexistence with 802.11 wireless LANs. The IEEE 802.11 standard defines interfaces and protocols for wireless nodes to communicate with each other and with various access points on a network.
The IEEE 802.15 Working Group has made advances on several fronts since its formation. For example, in December of last year the group announced the selection of a design approach and corresponding language that depends on formal methods to ensure the correctness of the design. Specifically, it has selected the Telelogic Tau SDL Suite to develop the new 802.15 standard. Telelogic Tau uses the Specification and Description Language (SDL) to produce a formal design. SDL combines both a formal syntax and a graphical representation. It's a programming language that is object-oriented, formal and graphical, and it can be fully tested and exercised before implementation.
The IEEE 802.15 Working Group is developing a draft standard based on Bluetooth version 1.0b. Bluetooth is an open specification for the wireless communication of data and voice based on a low-cost, low-power, short-range (around 10 meters or just over 30 feet) radio link built into a microchip. The Bluetooth Special Interest Group (SIG) was created to quickly develop a de facto standard to meet the communication needs of new mobile devices.
Bluetooth enables laptops, cellular phones, headsets, personal digital assistants (PDAs) and other types of portable communications devices to communicate with one another and with several types of appliances such as printers, desktops and fax machines without cables. This wireless, radio-based system technology will allow users to answer their mobile phone with a wireless headset, download e-mail from the cellular phone to the laptop even if it remains in the briefcase, print e-mail messages received on the PDA, and take photos and download them to the laptop and desktop simultaneously via e-mail.
Bluetooth has developed ad hoc networks called piconets, which are dynamically created as they are required, and consist of up to eight nodes, any of which can be a slave or master. That arrangement is highly consistent with a communications architecture where a variety of personal devices may be entering and leaving the network at random times.
Conveniently, major Bluetooth development efforts are also using SDL to specify, design and build Bluetooth-based products.
The result of the IEEE 802.15 Working Group's efforts will be a specification that allows vendors to produce the MAC and PHY communications layers of a WPAN device that will likely be compatible with existing wireless standards. The specification will likely be implemented as a low-power, single-chip solution that can be integrated into existing designs, or form the basis for new classes of products.
WPAN chips running TCP/IP software, or even using a special lightweight communications protocol, can be embedded into very small and nonintrusive devices, such as medical monitors, pagers and perhaps even wristwatches. Individual software applications can be more oriented toward processing data, without the requirement that the data be accessible to the user on the device.
This means that new personal digital products can be designed for function rather than for easy data display. In a coordinated personal network, a user may have a pager, cellular telephone, personal stereo, vital signs monitor and PDA, but only the larger and more functional PDA would have a user interface. The other devices would automatically transmit data to the PDA for display. Likewise, the user would have applications on the PDA for controlling each of the other devices.See related chart