Wireless Communications Hardware and Applications
The following are wireless communications system configurations in the form of hardware and applications as well as sample installation schematics, as shown in Figures 5 to 8 12:
- Handheld communications terminal
- Wireless interface processor
- Remote data collection
- Example of an ArielNet wireless communications application
Figure 5 Single HHCT user application.
Figure 6 Using a modem as a message repeater.
Figure 7 Multiple HHCT users.
Figure 8 Multiple HHCT users over a wide area network (WAN).
Handheld Communications Terminal
The handheld communications terminal (HHCT) consists of a liquid crystal display (LCD), 40-key keyboard, and RF modem housed in a lightweight, portable case. The low-power microprocessor in the HHCT provides the processing and communications functions. The HHCT unit provides most of the functions of an ANSII standard terminal. The HHCT is battery-operated for up to 12 hours on a charge and has provisions for connecting a bar code wand as an additional data-collection device.
Communications between the wireless interface processor (WIP) and HHCT are carried over a narrowband FM radio channel at a rate of 9600 baud. Any number of HHCTs can be addressed by the WIP as each HHCT has a unique identification number. The communications process is transparent to the user.
Wireless Interface Processor
The wireless interface processor (WIP) is a small electronic enclosure that houses the microprocessor, the radio transmitter, the radio receiver, and the antenna and communications interface. A WIP provides a connection to fixed resources such as instruments, computers, machinery, inventory, and property. The WIP provides the communication path from a remote site to a host system, as well as to HHCTs. The host system provides access to information such as inventory databases, equipment status and scheduling, process status, and control. A WIP also allows the HHCT user to access networks such as the Internet and its global information services, including email.
Remote Data Collection
A remote data collection system can be implemented by using a wireless interface processor connected to the serial communications port of a computer system that has an inventory database application running. A handheld communication terminal with a bar-code scanner attached can then be used to communicate inventory data over a large area. By connecting a bar-code scanner, the HHCT can be used as an inventory-control or data-capture device.
The WIP is connected to the communications port (COM port) of the host computer. The host computer has its console assigned to the COM port and is executing an inventory or database application. The HHCT now can function as the computer console and provide data gathering and control of the host computer at up to 1,000 feet away.
The wireless components of the ArielNet Wireless Communications System12 operate in compliance with Federal Communications Commission allocations (part15) for license-free operation. This puts the communication range for each element of the wireless network at 1,000 feet. With an array of devices, much larger areas can be covered.
Example of an ArielNet Wireless Communications Application
This application describes the use of wireless communications and the wireless interface processor in a product delivery service enterprise. The enterprise is a bakery, and the problem is inventory control. The bakery would like to sell all of its product while it is still fresh. Trucks are loaded each morning with the product, and each evening the trucks return with some product not sold that day. The product dispatcher would like a correct inventory of day-old products at the start of the day and would like to have them placed on the truck so they are delivered to the correct customers. The delivery trucks each have a computer and an ArielNet WIP. The truck computer could be a notebook computer system that provides customer order information, truck inventory, and route information to the driver. The truck computer also connects to a bar-code reader that can read the bar codes on the product. Information is sent to the truck computer each morning as it is loaded, and updated information is sent back each evening by wireless to the bakery's main control computer.
Bakery Delivery and Product Control Sequence
The bakery computer sends customer information and the routing schedule to the truck computer. As the truck is loaded, each product is scanned with the bar-code scanner, and the count is entered into the truck computer.
The truck computer communicates to the people loading the truck that the truck has the correct product loaded and sends this information to the bakery computer. The driver follows the computer route and scans each customer's product as it is delivered. The driver then returns to the terminal at the end of the day. As the truck is unloaded, any undelivered product is scanned. This information is sent to the bakery computer. If the information is complete, the driver is relieved; otherwise, corrective action is taken.
Next, let's look at narrowband and broadband personal communications service (PCS). This part of the article will also cover the pros and cons of wireless LANs in the enterprise and the technology options that they offer. It will also look at how the mobile nature of wireless communications provides consumers with the opportunity to access from any place at any time.