WO2002054634A1

WO2002054634A1 - Controller for wireless optical communication system

Info

Publication number: WO2002054634A1
Application number: PCT/KR2001/002308
Authority: WO
Inventors: Su-Chan Kim; Myung-Soo Ahn; Se-Ho Park; Jung-Hyuck Cho; Seung-Yong Shin
Original assignee: Standard Laser System Co., Ltd
Priority date: 2000-12-29
Filing date: 2001-12-29
Publication date: 2002-07-11
Also published as: KR20020056828A

Abstract

The disclosure is relevant to a control device for a wireless optical communication system including a trasmittion unit for converting a trasmission data signal into a laser beam and a reception unit for converting the laser beam into reception data signal. The control device is comprised of: a temperature sensor for sensing a temperature in the wireless optical communication system; a CCD array for divisionally receiving the laser beam at cells; a controller for adjusting transmission /reception angles at the units of trasmission and reception; a microprocessor for operating the controller to set the trasmission and reception angles to optimal angles. The invention provides an optimal operation temperature by sensing an internal temperature of the wireless optical communication system, and an optimal receipt condition of a laser beam by controlling pans and tilts in the trasmission and reception units. The system can inform a management system if a data signal is not received for a predetermined period of time, and enables wireless and serial communications to be controllable from a remote site.

Description

CONTROLLER FOR WIRELESS OPTICAL COMMUNICATION

SYSTEM

Technical Field The present invention relates to wireless optical communication systems in general, and more specifically to control devices employed in wireless optical communication systems. The control devices provide a stable data transmission operation of high quality by connecting networks to free space (or air space), optimizing operation temperature by sensing an internal temperature of the wireless optical communication system, and regulating conditions with transmission and reception angles of a laser

Background Art

With the recent spread of LAN (Local Area Network), WAN (Wide Area Network), or Internet communications, there are various kinds of data transmission methods.

It is practically usual, in implementing the data transmission, to construct a network system with wires, e.g., coaxial cables or RF, in a local area, while with optical fibers by an optical communication technique in a wide area. The data transmission through wires (e.g., coaxial cables or RF) or through optical fibers needs a specific line for transmitting data. The specific transmission line is scaled in accordance with several parameters such as rransmittal sections, distances, speeds (or a data rate), and data capacities. And, an installation cost rises according to the scale of the transmission line. Therefore, network providers are demanded to provide high-quality data transmission services with lower costs for installation and maintenance.

Such a demand causes an advancement of wireless optical communication systems through free space. In general, the wireless optical communication system is basically composed of a transmitter, a receiver, and an information channel.

The transmitter modulates an information signal to be transmitted into a signal with a. proper format that is adaptable to be transmitted through the information channel (i.e., the free space), and then sends the modulated signal through the free space via a laser beam. After that, the receiver receives the laser beam and then demodulates the laser beam into an electrical signal.

In the wireless optical communication system, the maximum efficiency of transmission is obtained when transmission and reception angles of the laser beam are identical. In addition, heat is inevitably emitted from provided therein the transmitter due to a high-temperature laser beam. And, the wireless optical communication system is much affected by an environmental temperature since it conducts a data transmission with being exposed in a free space.

On the other hand, a conventional system employs an external sensor to monitor and adjust conditions of a reception signal in order to regulate the transmission and reception angles of the laser beam. Thus, it is impossible to conduct the adjusting works apart from a place where the system is installed, thereby increasing a working time. Moreover, the conventional system with a structure of emitting generated heat is not appropriate to operate at mountain areas or places experiencing abrupt variations of temperature.

Also, if the system is accidentally disabled to prevent transmission or reception of data due to mechanical or electrical problems, it takes a long time to correct the abnormal situation because a system manager cannot identify the current disorder promptly.

Furthermore, there is a limit in operating a multiplicity of wireless optical communication systems, because the conventional systems are independently established and operated, and where not cooperatively developed throughout their operational histories.

Disclosure Of Invention

It is an object of the invention, in order to obviate or mitigate one or more of the above-identified problems, to provide control devices for obtaining optimal transmission and reception angles of laser beams in a wireless optical communication system.

It is another object of the invention to provide a wireless optical communication system capable of maintaining an optimal operation temperature therein.

It is another object of the invention to provide a wireless optical communication system capable of informing a remote site that there is no presence of a received data signal.

It is another object of the invention to provide a wireless optical communication system capable of controlling transmission and reception angles of a laser beam from a remote site.

It is another object of the invention to provide a wireless optical communication system ensuring reliable management by storing and transmitting to a management system, information about current states of operation and control.

Brief Description of the Drawings

Figure 1 is a block diagram schematically illustrating an interconnection feature for transmitting and receiving data between control devices of a wireless optical communication system according to the present invention.

Figure 2 is a block diagram illustrating an interconnection feature between the transmission unit and control devices in the wireless optical communication system shown in Figure 1. Figure 3 is a block diagram illustrating an interconnection feature between the reception unit and control . devices in the wireless optical communication system shown in Figure 1.

Figure 4 is a flowchart showing an operational procedure of the microprocessor shown in Figures 2 and 3.

Best mode for Carrying Out the Invention

According to an aspect of the invention, there is provided a control device for a wireless optical communication system having a transmission unit converting a data signal into a laser beam signal and a reception unit converting the laser beam into a data signal, the control device comprising: a temperature sensor for detecting temperature of the transmitter and receiver; a CCD array for divisionally receiving the laser beam signal at plural cells thereof and for outputting cell signals; a controller for adjusting an transmission/reception angle of the laser beam from the transmitter or at the receiver; and a microprocessor for controlling temperature of the system in response to an output from the temperature sensor and for operating the controller to optimize the transmission/reception angle in response to cell signals from the CCD array.

It is available for the microprocessor to be associated with a keystroke for providing a control value to operate the controller, a serial port for tiansntitting/receiving serial data to operate the system, a wireless communication unit connectable to a remote site, or a storage unit for containing a result of controlling in the system.

The microprocessor controls the system to discharge heat when a current temperature is higher than a predetermined level, and to generate heat when a current temperature is lower than the predetermined level. And also, the microprocessor informs a remote site, through a wireless communication unit, if a data signal is not received at the receiver for a predetermined period of time.

In addition, the microprocessor controls the controller to match the transmission/reception angle to a predetermined reference beam position when the cell signal from the CCD array does not accord with a predetermined reference beam position. On the other hand, the microprocessor controls the controller to settle the transmission/reception angle at a position where signal strength is the highest when the cell signal from the CCD array does not accord with a predetermined reference beam position.

According to another aspect of the invention, a present wireless optical communication system comprises: a transmission unit converting a data signal into a laser beam signal that is to be sent to an air space; a reception unit converting the laser beam into a data signal; a temperature sensor for detecting temperature of the transmitter and receiver; a CCD array for divisionally receiving the laser beam signal at plural cells thereof and for outputting cell signals; a controller for adjusting an transmission/reception angle of the laser beam from the transmitter or at the receiver; and a microprocessor for controlling temperature of the system in response to an output from the temperature sensor and for operating the controller to optimize the transmission/reception angle in response to cell signals from the CCD array.

Now, it will be explained about preferred embodiments of the invention in conjunction with the drawings Figures 1 through 4. Figure 1 illustrates a feature of interfacing data signals between control devices employed in a wireless optical communication system according to an embodiment of the present invention, including networks 100 and 1000, network interfaces 200 and 900, transmission units 300 and 800, reception units 500 and 700, and a free space 600. The network interface 200, and the transmission and reception units, 300 and 500, is included within a control block 150 of the present wireless optical communication system, together with other useful control devices explained later in detail.

As shown in Figure 1, the control block 150 is interposed between the first and second networks, 100 and 1000, so as to conduct a networking operation through the free space 600, that is, wireless not wire, between the networks.

The control block 150 is conditionally adaptable to transmission/reception for digital data of audio/video sets, or for text data of various communication modes such as SDH (synchronous digital hierarchy) /SONET (synchronous optical network), ATM (asynchronous transfer mode), and gigabit Ethernet, or fast Ethernet. The control block 150 also carries out a temperature adjustment operation in the wireless optical commiinication system.

As the system wirelessly networks through the free space with being exposed in the atmosphere, the temperature in the system would be influenced by seasonal variations, e.g., higher during summer, due to direct rays of light, or be lower during winter. Thus, the control block 150 monitors a current temperature in the system and then regulates the temperature to maintain an optimal system temperature. Meanwhile, with respect to the accordance between transmission/reception angles of a laser beam in the environment of the free- space networking, the control block 150 overcomes the difficulties in adjusting the transmission/reception angles within minute ranges at an installation place inconvenient to physically access by a manager. By the control block 150, it is possible to establish an optimal transmission/reception angle automatically, as well as offering a controllable function by means of an operation with keystrokes, computers, or mobile communications.

Figure 2 details a functional construction of control devices associated with the transmission unit 300 shown in Figure 1. There are provided control devices, such as a laser driver 340, a heat sink 410, a pan motor 452, a tilt motor 454, a motor controller 456, a microprocessor 458, a wireless communication unit 460, a keystroke unit 462, a serial port 464, a storage unit 466, and a temperature sensor 468. It is usual that, as shown in Figure 2, an external signal modulator 430, a multiplexer 440, an output amplifier 360, a signal transmitter 370, and an optical filter 380 are embedded in a single body of a telescope 160. Therefore, adjusting a transmission angle of a laser beam can be accomplished by adjusting an outlet angle of the telescope 160. The pan motor 452, or the tilt motor 454, is composed of a stepping motor adjusting the outlet angle of the telescope 160 to be movable up, down, left, or right in response to control signals provided from the motor controller 456.

In order to accord accurate transmission/reception angles between wireless optical communication systems, the pan motor 452 and the tilt motor 454 are precisely driven with accuracy of 0.0001° through plural operation steps of 1-1024.

The laser driver 340, for generating a laser beam, easily warms up due to its inherent heat generation properties, and thereby occasionally reaches a high temperature that is deleterious to a normal operation. The temperature sensor 468 detects a current temperature of the laser driver 340 through the heat sink 410 that discharges the heat generated from the laser driver 340. The temperature sensor 468 applies a temperature sensing signal TS to the microprocessor 458. The microprocessor 458 controls the temperature and a transmission angle, and is connected with various operative equipments, such as a manager's system through the wireless communication unit 460, or a portable computer through the serial port 464. Therefore, it is possible to control the present wireless optical communication system by means of portable computers or remote computers connectable thereto through a wireless network.

The keystroke unit 462, connected to the microprocessor 458, is provided to directly control the pan and tilt motors, 452 and 454, to adjust a transmission angle (or an outlet angle of the microscope 160) by entering a desirable value of the angle. The storage unit 466 stores data generated during the adjustment controlled by the microprocessor 458.

As operative terminal means for adjusting the transmission angle, the wireless communication unit 460 may be a mobile terminal operable in a CDMA

(code-division multiple access) environment, as an example. It is available for the keystroke unit 462 to use a keypad equipped with numeral and function keys, and for the storage unit 466 to use a RAM (ransom access memory).

Figure 3 details a functional construction of control devices associated with the reception unit 500 shown in Figure 1, including a CCD (charge-coupled device) array 470, a signal receiver 540, and a demultiplexer 550. First, a laser beam from the free space is received at the optic unit 560 through an optical filter 570. The laser beam output from the optic unit 560 is demultiplexed by wavelengths in the demultiplexer 550.

The signal receiver 540 converts the laser beam signal, passing through the optic unit 560 and demultiplexer 550, into an electrical signal (hereinafter, a reception data signal). The reception data signal generated from the signal receiver 540 is applied to the signal demodulator 520 and the microprocessor 458. The microprocessor 458 detects the reception data signal RS from the signal receiver 540 and then confirms there is a normal reception state for a laser beam.

The laser beam from the demultiplexer 550 is also applied to the CCD array 470. The CCD array 470 is positioned at the central region of the telescope, and is, for example, composed of four quad-cells, each of which generates a cell signal CS. The cell signals CS are applied to the microprocessor 458.

After that, the microprocessor 458 evaluates distribution profiles from the cell signals CS, and converts the evaluation results into control parameters for the motor controller 456 in correspondence with a predetermined reference position of a laser beam. By this procedure, the microprocessor 458 continuously operates the motor controller 456 until the distribution profile of the cell signal CS accords with the reference beam position.

On the other hand, the microprocessor 458 may also take the strength of the cell signal CS into account to adjust a reception" angle, without evaluating the distribution profiles for a laser beam, as in the former procedure. That is, the microprocessor 458 instructs the motor controller 456 to select an angle point, which receives largest total output from the cell signals, as a target for an optimal reception angle.

In approximating a reception angle of the laser beam at an initial state, it is necessary to optionally perform an adjusting operation rather than evaluating the cell signals CS. In this case, the adjusting operation is practicable by employing a computer connected to the microprocessor 458 through the serial port 464, the keystroke unit 462, or the wireless communication unit 460, from a remote site. Figure 4 shows typical sequential steps conducted by the microprocessor

458 shown in Figures 2 and 3, for regulating a temperature of the laser driver 340 and the transmission/reception angles in the present wireless communication system.

First, at a step SI 10, the microprocessor 458 detects a current temperature of the laser driver 340 by means of the temperature sensor 468, and then determines whether or not the sensed temperature is within a predetermined reference range, e.g., -40~60°C as normal, at a step S120. In the case of a non- optimal temperature, if it is determined at a step S260 that the temperature sensing signal TS from the sensor 468 indicates a current temperature is higher than the reference, the heat sink 410 is driven to discharge the heat of the laser driver 340 at a step S270. If a current temperature is lower than the reference, the temperature sensing signal TS makes the heat sink 410 turn off. When a current temperature of the laser driver 340 is much lower than the reference, that is, the temperature conditions is insufficient to generate a laser beam, thermal wires (not shown) heat up the laser driver 340 at a step S280.

When a current temperature of the laser driver 340 is within the normal reference the microprocessor 458 detects the reception data signal RS from the signal receiver 540 at a step S130 and checks whether or not the reception data signal RS is normal at a step S140. If there is an abnormal reception of RS, the microprocessor 458 informs a manager's system of the presence of the abnormal RS at a step s 150.

While, if the reception data signal RS is stationing normally, the microprocessor 458 detects the cell signal CS from the CCD array 470 at a step S160. At this time, if it is determined at a step S170 that the cell signal CS from the CCD array 470 is not received at an optimal transmission reception angle, the microprocessor 458 operates the motor controller 456 to establish an optimal condition of reception at a step S180.

While it is determined at the step SI 70 that the cell signal CS from the CCD array 470 provides an optimal angle of transmission/reception, the microprocessor 458 checks whether there is a presence of an input from the keystroke unit 462 at a step SI 90. If there is an input from the keystroke unit 462, the microprocessor 458 operates the motor controller 456 to adjust a transmission/reception angle in response to the input of the keystroke unit 462 at a step S200.

In the same manner, if there is a presence of a signal to control a transmission/reception angle from the serial port 464 at a step S210, the microprocessor 458 operates the motor controller 456 to adjust a transmission/reception angle in response to the signal from the serial port 464 at a step S220.

And, if there is a request from a manager's system, through a wireless communication network from a remote site at a step S230, the microprocessor 458 offers a connection between the control devices and the manager's system through the wireless communication unit 460 to adjust a transmission/reception angle by the manager's remote control at a step S240. During this adjustment, the microprocessor 458 transfer data held in the storage unit 466 to the manager's system in response to a request from the manager's system.

Finally, at a step S250, the microprocessor 458 inputs data, which has been obtained from the control processes, into the storage unit 466.

Thus, it is possible for the manager's system to operate an integrative manage the wireless optical communication system, because it can take and use the data stored in the storage unit.

According to the forgoing discussion, the invention provides solutions overcoming the various disadvantages involved in the conventional wireless optical communication systems such as: a conventional system employs an external sensor to monitor and adjust conditions of a reception signal in order to regulate the transmission and reception angles of the laser beam. Thus, it is impossible to conduct the adjusting works apart from a place where the system is installed, resulting in a longer working time. Moreover, the conventional system with a structure of emitting generated heat is not appropriate to operate at mountain areas or places experiencing abrupt variation of temperature.

The invention provides an optimal operating temperature by sensing an internal temperature of the wireless optical communication system, and further provides an optimal receipt condition of a laser beam by controlling pans and tilts in the transmission and reception units. The system can inform a management system if a data signal is not received for a predetermined period of time, and enables wireless and serial communications to be controllable from a remote site.

Claims

What Is Claimed Is :

1. A control device for a wireless optical communication system having a transmission unit converting a data signal into a laser beam signal and a reception unit converting the laser beam into a data signal, the control device comprising: a temperature sensor for detecting temperature of the transmitter and receiver; a CCD array for divisionally receiving the laser beam signal at plural cells thereof and for outputting cell signals; a controller for adjusting a transmission/reception angle of the laser beam from the transmitter or at the receiver; and a microprocessor for controlling temperature of the system in response to an output from the temperature sensor and for operating the controller to optimize the transmission/reception angle in response to cell signals from the CCD array.

2. The control device of claim 1, wherein the microprocessor comprises a keystroke for providing a control value to operate the controller.

3. The control device of claim 1, wherein the microprocessor comprises a serial port for tiansmitting/receiving serial data to operate the system.

4. The control device of claim 1, wherein the microprocessor comprises a wireless commumcation unit connectable to a remote site.

5. The control device of claim 1, wherein the microprocessor comprises a storage unit for containing a result of controlling in the system.

6. The control device of claim 1, wherein the microprocessor controls the system to discharge heat when a current temperature is higher than a predetermined level, while to generate heat when a current temperature is lower than the predetermined level.

7. The control device of claim 1, wherein the microprocessor informs a remote site, through a wireless communication unit, of an absence of the data signal at the receiver for a predetermined length of time.

8. The. control device of claim 1, wherein.the microprocessor controls the controller to match the transmission/reception angle to a predetermined reference beam position when the cell signal from the CCD array does not accord with a predetermined reference beam position.

9. The contiol device of claim 1, wherein the microprocessor controls the controller to settle the transmission/reception angle at a position where a signal strength is the strongest when the cell signal from the CCD array does not accord with a predetermined reference beam position.

10. A wireless optical communication system comprising: a transmission unit converting a data signal into a laser beam signal that is to be sent to an air space; a reception unit converting the laser beam into a data signal; a temperature sensor for detecting temperature of the transmitter and receiver; a CCD array for divisionally receiving the laser beam signal at plural cells thereof and for outputting cell signals; a controller for adjusting an transmission/reception angle of the laser beam from the transmitter or at the receiver; and a microprocessor for controlling temperature of the system in response to an output from the temperature sensor and for operating the controller to optimize the transmission/reception angle in response to cell signals from the CCD array.