In a device network, devices such as printers, workstations, or mobile terminals are operably linked to process information using communication resources such as wireless channels or cables. The information includes, for example, data for processing by the devices or control signals for controlling such devices. Typically, data or control signals are provided from one or more devices to one or more other devices. Devices that receive data usually process such data based on control signals associated with the data.
Generally, devices that receive data, referred to hereinafter as “target devices”, have to be selected prior to receiving and processing the data. Selection of a target device includes identifying that target device and is usually done by a user who, via a selecting device, provides one or more control signals that includes selection criteria to select the target device (e.g. a printer). The selecting device can be, for example, a handheld mobile terminal (e.g. a Personal Digital Assistant (or PDA)) at which the user provides the selection criteria. After receiving the selection criteria, a target control signal is generated and transmitted from the selecting device to a controller for controlling the target device. In response to the target control signal, the controller sets the target device to receive the data via the communication resources, whereupon, the target device is able to be utilised.
Communicating control signals to select target devices requires communication elements such as transmitters and receivers that are either a part of the devices or are coupled to such devices. To communicate data or control signals to, for example, a printer, a user has to provide selection criteria that identify the printer. A device address, when known a priori, is typically used as a selection criteria. However, selection by physically pointing to the device is more natural and user friendly, and does not require knowledge of device address.
One existing technique to perform selection by physically pointing at the device is described, for example, in U.S. Pat. No. 5,963,145, issued to Escobosa on Oct. 5, 1999. This patent describes a system having a hand held transmitter that transmits position signals at different infrared frequencies, and along divergent pointing axes, towards a device to be selected. Based on the signal strength of these position signals, a sensor coupled to the selected device determines position of the hand held transmitter. However, in the system as described in U.S. Pat. No. 5,963,145, interference problems are likely when more than one hand held transmitter is used at the same time. Such interference problems arise because target devices that receive the position signals have to be wide-angle sensitive (for example, due to the use of a wide-angle photo-diode), and this allows interfering signals to be received in addition to desired control signals. A second disadvantage of the system as described in U.S. Pat. No. 5,963,145 is that it mandates the use of IR.
In PDAs, mobile terminals and printers, provision for RF wireless communication (for example, using Bluetooth™, which is described in http://www.bluetooth.com) is rapidly replacing IR communication. These devices are typically fitted with omni-directional antennas. As such, in this context, directional techniques such as described in U.S. Pat. No. 5,963,145 are rendered useless.
Therefore, in view of the above limitations of existing techniques to select a target device, a need clearly exists for an apparatus and method for selecting the target device in a device network that is feasible in the context of non-directional wireless communication, without requiring additional support of directional communication such as IR, and is devoid of the aforementioned drawbacks of the IR based system.