Method and apparatus for power level control in area networks

• US 4,816,825 A
• Filed: 02/27/1987
• Issued: 03/28/1989
• Est. Priority Date: 02/27/1987
• Status: Expired due to Term

• Current Assignee: Zenith Electronics Corporation (LG Corporation)
• Original Assignee: Zenith Electronics Corporation (LG Corporation)
• Inventors: Chan, John K., Sirazi, Semir D., Reichard, Gordon E.
• Primary Examiner(s): 4
• Assistant Examiner(s): Yusko, Donald J.
• Application Number:
  US07/019,808
• Time in Patent Office: 760 Days
• Field of Search: 340/825.5, 340/825.06, 379/66, 379/347, 379/348, 379/401, 370/17, 375/13, 455/10
• US Class Current: 370/447
• CPC Class Codes: H04L 12/2801 Broadband local area networks

Abstract

The disclosure depicts in a two-way broadband communications network employing a carrier sense multiple access with collision detection protocol an apparatus and method for controlling station transmit signal levels. Signal level detection circuitry is coupled to one or a plurality of locations in the network transmission medium to determine the signal level generated by each of the plurality of stations periodically transmitting into the medium. The detected signal level from a station is compared to a predetermined range of appropriate values for the station and where the station is transmitting signals outside of the predetermined range, a correction factor is applied to the station to adjust the transmit levels of the station.

Claims

1. In a two way broadband data communications system comprising a plurality of stations communicating with one another through a headend frequency translator or a remodulating head end, wherein said stations are adapted to transmit signals on a reverse channel and to receive signals on a forward channel, and wherein stations contend for access to said communications system under a carrier sense multiple access with collision detection protocol, an improvement comprising:

measurement means included in each station adapted to generate an output signal responsive to the level of a signal received by a receiving station;

means included in each station for identifying whether said signal was generated by said receiving station;

transmit level adjustment determination means included in each station, said transmit level adjustment determination means including means responsive to indication from said identifying means that said receiving station transmitted said signal and to said output signal for calculating an appropriate transmit level adjustment required of said receiving station to achieve a predetermined signal level on said forward channel for signals transmitted by said receiving station on said reverse channel, and further including means for generating an appropriate transmit level adjustment command for said receiving station; and

means included in each station responsive to said appropriate transmit level adjustment command for controlling the transmit level of said receiving station;

such that each station adjusts the transmit level of each respective station on said reverse channel in response to the levels of signals on said forward channel;

whereby said system maintains the levels of signals on said forward channel in a range calculated to avoid capture of the detector of any one station by any one of a plurality of signals on said forward channel.

2. In a two-way broadband data communications system comprising a plurality of stations communicating with one another through a head-end frequency translator or a remodulating headend, wherein said stations are adapted to transmit signals on a reverse channel and to receive signals on a forward channel, and wherein stations contend for access to said communicating system under a carrier sense multiple access with collision detection protocol, an improvement comprising:

measurement means coupled to said forward channel for generating an output signal responsive to the level of a signal on said forward channel;

transmit level adjustment means connected to said measurement means, said transmit level adjustment means including means for identifying a source station of a signal on said forward channel, and means responsive to said output signal for calculating and generating a transmit level adjustment command for said source station appropriate to maintain the level of said signal on said forward channel within a predetermined range of values;

means for transmitting said transmit level adjustment command to said source station; and

means included in said source station responsive to said transmit level adjustment command for controlling the transmit level of said source station;

such that said system is provided with a system for automatic adjustment of the transmit level for each station in response to the levels of signals on said forward channel;

whereby said system maintains the levels of signals on said forward channel in a range calculated to avoid capture of the signal detector of any station in said system by any one of a plurality of signals on said forward channel.