Excavating
Patent
1995-10-12
1998-03-17
Baker, Stephen M.
Excavating
H03M 1300, H03M 1312
Patent
active
057295573
ABSTRACT:
A method and apparatus for using multiple code rates for forward error correction in a cellular digital data radio communication system. Each base station broadcasts a quantity called the power product (PP), which is equal to the base station transmit power, P.sub.BT, multiplied by the power level received at the base station, P.sub.BR. For a mobile unit to determine its appropriate transmit power, P.sub.MT, requires measuring the power received, P.sub.MR, at the mobile unit and performing the following calculation: P.sub.MT ==PP/P.sub.MR. When channel path loss is large, it is possible that the power control calculation will return a value greater than the maximum transmit power capability of the mobile unit. In such a case, the mobile unit selects a lower code rate. Base station receiver sensitivity improves as the code rate decreases, so the result is similar to increasing the transmitter power. In the preferred embodiment, the invention uses 3 different code rates. In most cases, the code rate used is rate 2/3, but when a mobile unit determines that it needs more transmit power than it is capable of providing, the code rate is changed to 1/2, and in severe cases the code rate is changed to 1/3. Other features are that mobile unit code rate selection can be based on the quantity of data to be transmitted, and a base station can determine the code rate used by a mobile unit by attempting to decode all code rates and choosing the best result.
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Gardner Steven H.
Hardin C. Thomas
Petranovich James E.
Baker Stephen M.
Land John
Pacific Communication Systems, Inc.
Violette J. P.
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