Browse Prior Art Database

Physical Layer Repeater for Infrared Cableless Local Area Network

IP.com Disclosure Number: IPCOM000038740D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 3 page(s) / 27K

Publishing Venue

IBM

Related People

Clark, GL: AUTHOR [+5]

Abstract

A technique is described whereby an infrared (IR) cableless local area network (LAN) repeater utilizes time slot signals which are physically layered. The technique utilizes a media access method for repeaters, so as to capture the ether in a predictable and orderly fashion. The concept uses a physical time slot orientation of the media, thereby eliminating the need to rewrite the basic input/output system (BIOS) or application software. The physical layer is structured in such a way so as to provide the following features, or advantages, over other repeater schemes: The repeater signals will never collide with each other. . PACKET INFORMATION IS ONLY REPEATED IF IT IS IN THE LINK PATH. . Will recognize that the packet information is not in the link path. . RETAIN PACKET INFORMATION IN ITS ORIGINAL DATA CONTENT. .

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Physical Layer Repeater for Infrared Cableless Local Area Network

A technique is described whereby an infrared (IR) cableless local area network (LAN) repeater utilizes time slot signals which are physically layered. The technique utilizes a media access method for repeaters, so as to capture the ether in a predictable and orderly fashion. The concept uses a physical time slot orientation of the media, thereby eliminating the need to rewrite the basic input/output system (BIOS) or application software. The physical layer is structured in such a way so as to provide the following features, or advantages, over other repeater schemes: The repeater signals will never collide with each other. . PACKET INFORMATION IS ONLY REPEATED IF IT IS IN THE LINK PATH. . Will recognize that the packet information is not

in the link path. . RETAIN PACKET INFORMATION IN ITS ORIGINAL DATA CONTENT. . ADD OR DELETE REPEATERS WITHOUT RECONFIGURING THE SYSTEM. Provide simulation capability through the use of a

deterministic computer. In prior art, utilization of repeaters in the infrared transmission of data, as in LAN applications, presented significant problems due to such items as the physical movement of objects within a room, the amount of light in a room and other objects which may affect the flow of information. To cope with these variables, it was often necessary to rewrite BIOS, introducing a read-only memory (ROM) change or rewriting application software. The technique described herein is a media access method whereby time slots control the repeater in an orderly fashion. Four different classes of media access slots are used: 1) System acknowledge (ACK) slots 2) Repeater ACK slots 3) Repeater slots 4) Random slots for system unit access The four media access time slots are typically sectioned, as shown in the figure, whereby the gate array in the repeater is able to assemble an acknowledge, an ACK, and transmit it after receiving a packet in one of the first nine media access time slots. The system ACK slot 1 has the highest priority since it informs repeating stations that a specific packet has reached its destination. A repeater receiving a system ACK of a matching packet not on a link list will purge that packet. The eight slots which make up the repeater ACK slots (2) will repeat the same system...