Control method and apparatus for wireless data link

• US 5,321,542 A
• Filed: 11/08/1993
• Issued: 06/14/1994
• Est. Priority Date: 10/29/1990
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Freitas, Richard F., Harrison, Colin G., Hortensius, Peter D.
• Primary Examiner(s): Woodiel, Donald O.
• Assistant Examiner(s): BACARES, RAFAEL D
• Application Number:
  US08/148,190
• Time in Patent Office: 218 Days
• Field of Search: 359/113, 359/114, 359/123, 359/124, 359/125, 359/126, 359/135, 359/136, 359/137, 359/144, 359/152, 359/153, 359/159, 359/161, 359/165, 359/172, 370/84, 340/825.54
• US Class Current: 398/127
• CPC Class Codes: H04B 10/1149 Arrangements for indoor wireless networking of information

Abstract

Methods and apparatus for operating an optical communications system having at least two communicating entities (10,12). In accordance with a method of the invention a first step transmits communication link control information from a first entity to a second entity over a first optical channel having a first data bit rate. Responsive to the transmitted communication link control information, a second step of the method transmits data information from the second entity to the first entity over a second optical channel having a second data bit rate that is greater than the first data bit rate. The first optical channel is preferably a relatively low-bandwidth diffuse transmission infrared radiation channel. The second optical channel is preferably a relatively high-bandwidth infrared channel. One of the entities is a network adapter coupled to a wired network. The network adapter is preferably ceiling mounted. The other entity may be a mobile data processor. A plurality of mobile data processors may be served by one network adapter.

Claims

1. A method of operating a wireless optical communications system having at least two communicating entities, comprising the steps of:

providing each of the at least two communicating entities with first means for transmitting and for receiving information over a first wireless optical channel and with second means for transmitting and for receiving information over a second wireless optical channel such that each of the at least two communicating entities are capable of bidirectional communication over the first wireless optical channel and over the second wireless optical channel, wherein each of the first means for transmitting and receiving information operates at a first wavelength and a first data bit rate, wherein each of the second means for transmitting and receiving information operates at a second wavelength and at a second data bit rate, and wherein the first wavelength is longer than the second wavelength and the first data bit rate is less than the second data bit rate;

transmitting communication link control information from a first entity to a second entity over the first wireless optical channel at the first data bit rate; and

responsive to the transmitted communication link control information that is received over the first wireless optical channel, transmitting data information from the second entity to the first entity over the second wireless optical channel at the second data bit rate, wherein the communication link control information is transmitted with a bandwidth that is less than a band width with which the data information is transmitted.

2. A method as set forth in claim 1 wherein the first optical channel is a diffuse transmission infrared radiation channel and wherein the second optical channel is a line-of-sight infrared radiation channel.

3. A method as set forth in claim 1 and further comprising the steps of receiving the transmitted data information with the first entity and re-transmitting the received data information form the first entity to a conductor coupled to a communications network.

4. A method as set forth in claim 3 and further comprising the steps of:

transmitting communication link control information from the second entity to the first entity with the first optical channel; and

responsive to the transmitted communication link control information, transmitting data information other than communication link control information from the first entity to the second entity with the second optical channel, the step of transmitting the data information including the initial steps of receiving the data information from the network with the first entity; and

buffering the information received from the network within the first entity.

5. A method as set forth in claim 2 wherein the second optical channel transmits with a modulation spectrum within a range of approximately 400 kHz to approximately 10 MHz, and wherein the first optical channel transmits with a modulation spectrum within a range of approximately 2 kHz to approximately 300 kHz.

6. A method as set forth in claim 1 wherein the first and the second optical channels each employ a TDMA technique having a repetitively transmitted data frame comprised of a plurality of slots, each slot comprising a plurality of fields including a data field.

7. A method as set forth in claim 6 wherein the step of transmitting communication link control information includes a step of transmitting an identification of at least one slot that is assigned to the second entity for transmitting the date information therein.

8. An optical communication system comprising at least one network adapter means coupled to a network and at least one data processing means optically coupled through a wireless link to the network adapter means, wherein the network adapter means and the data processing means each comprise means for transmitting and for receiving information with one another through a first, diffuse transmission infrared radiation channel at a first bit rate, and wherein the network adapter means and the data processing means each further comprise means for transmitting and for receiving information with one another through a second infrared radiation channel having a second bit rate that is greater than the first bit rate, the network adapter means and the data processing means each further comprising means for transmitting and for receiving wireless link control information with one another through the first, diffuse transmission infrared radiation channel, the network adapter means and the data processing means each also comprising means for transmitting and for receiving data information, other than wireless link control information, with one another through the second infrared radiation channel.

9. An optical communication system as set forth in claim 8 wherein the second infrared radiation channel transmits with a modulation spectrum between approximately 400 kHz to approximately 10 MHz and wherein the first, diffuse transmission infrared channel transmits with a modulation spectrum within the range of approximately 2 kHz to approximately 300 kHz.

10. An optical communication system as set forth in claim 8 wherein the network adapter means and the data processing means each comprise means for transmitting and for receiving the wireless link control information with one another through the first, diffuse transmission infrared radiation channel with a slotted TDMA protocol, and wherein the network adapter means and the data processing means each also comprise means for transmitting and for receiving the data information, other than wireless link control information, with one another through the second infrared radiation channel also with the slotted TDMA protocol.

11. An optical communication system as set forth in claim 8 wherein the network adapter means and the data processing means each comprise means for buffering data information transmitted to or received from the wireless link.

12. An optical communication system as set forth in claim 8 wherein the data processing means includes a single infrared transmitting means for transmitting both the first, diffuse transmission infrared radiation channel and also the second infrared radiation channel.

13. An optical communication system as set forth in claim 8 wherein the data processing means includes a first infrared transmitting means for transmitting the first, diffuse transmission infrared radiation channel and further includes a second infrared transmitting means for transmitting the second infrared radiation channel.

14. An optical communication system as set forth in claim 8 wherein the data processing means includes a single infrared receiving means for receiving both the first, diffuse transmission infrared radiation channel and also the second infrared radiation channel.

15. An optical communication system as set forth in claim 8 wherein the data processing means includes a first infrared receiving means for receiving the first, diffuse transmission infrared radiation channel and further includes a second infrared receiving means for receiving the second infrared radiation channel.

16. An optical communication system comprising at least one network adapter means coupled to a network and at least one data processing means optically coupled through a wireless link to the network adapter means, wherein the network adapter means and the data processing means each comprise means for transmitting and for receiving information with one another through a first, diffuse transmission infrared radiation channel at a first bit rate, and wherein the network adapter means and the data processing means each further comprise means for transmitting and for receiving information with one another through a second infrared radiation channel having a second bit rate that is greater than the first bit rate, wherein the network conforms to a TCP/IP protocol.

17. In a wireless infrared link communication system comprising at least one network adapter means coupled to a network and a plurality of data processing means optically coupled through the wireless infrared link to the network adapter means, a method for communicating between the network adapter means and each of the data processing means, comprising the steps of:

transmitting and receiving communication control information through a first, diffuse transmission infrared radiation channel having a first bandwidth; and

responsive to received communication control information, transmitting and receiving data information through a second infrared radiation channel having a second bandwidth that is greater than the first bandwidth.

18. A method as set forth in claim 17 and further comprising the steps of buffering within the network adapter means data information received from the network or from one of the data processing means.

19. A method as set forth in claim 17 and, in response to a condition wherein the second infrared radiation channel is not operable to transmit and receive the data information, further comprising a step of communicating the data information between the network adapter means and one or more of the data processing means only with the first, diffuse transmission infrared radiation channel.

20. In a wireless infrared link communication system comprising at least one network adapter means coupled to a network and a plurality of mobile data processing means optically coupled through the wireless infrared link to the network adapter means, a method of establishing communication between the network adapter means and one of the mobile data processing means, comprising the steps of:

before the mobile data processing means comes within operable communication range of the network adapter means through a first infrared data transmission channel,

transmitting and receiving communication control information between the mobile data processing means and the network adapter means through a second, diffuse transmission infrared radiation channel;

the control information including information for enabling the mobile data processing means to be assigned to an active group of mobile data processing means that is associated with the network adapter means; and

after the mobile data processing means comes within operable communication range of the network adapter means through the first infrared data transmission channel,

transmitting and receiving data information between the network adapter means and the mobile data processing means through the first infrared data transmission channel.

21. A network adapter for use in coupling a wired network to a wireless communication medium, the network adapter comprising:

means for coupling to the wired network; and

means for coupling to the wireless communication medium, the coupling means including first means for transmitting and for receiving modulated optical radiation having a first bandwidth having diffuse propagation characteristics associated therewith, the modulated optical radiation that is transmitted and received with the first means including wireless communication medium control information;

the means for coupling to the wireless communication medium further including second means for transmitting and for receiving modulated optical radiation having a second bandwidth that is greater than the first bandwidth, the modulated optical radiation that is transmitted and received with the second means including information other than wireless communication medium control information.

22. Network adapter means as set forth in claim 21 wherein the first means and the second means each operate within a range of optical wavelengths that is greater than approximately 700 nanometers.

23. Network adapter means as set forth in claim 21 wherein the second means includes means for transmitting with a modulation spectrum within a range of approximately 400 kHz to approximately 10 MHz, and wherein the first means includes means for transmitting with a modulation spectrum within a range of approximately 2 kHz to approximately 300 kHz.

24. A data processor for use with a wireless communication medium, the data processor comprising:

means for coupling the data processor to a wireless communication medium, including first means for transmitting and for receiving modulated optical radiation having a first bandwidth having diffuse propagation characteristics associated therewith, the modulated optical radiation that is transmitted and received with the first means including wireless medium communication control information;

the means for coupling to the wireless communication medium further including second means for at least receiving modulated optical radiation having a second bandwidth that is greater than the first bandwidth, the modulated optical radiation that is received with the second means including information other than wireless communication medium control information.

25. Data processing means as set forth in claim 24 wherein the first means and the second means each operate within a range of optical wavelengths that is greater than approximately 700 nanometers.

26. Data processing means as set forth in claim 24 wherein the second means includes means for receiving optical radiation having a modulation spectrum within a range of approximately 400 kHz to approximately 10 MHz, and wherein the first means includes means for transmitting with a modulation spectrum within a range of approximately 2 kHz to approximately 300 kHz.