[54] RANDOM ACCESS IN MOBILE RADIO TELEPHONE SYSTEMS
[75] Inventor: Paul W. Dent, Stehag, Sweden
[73] Assignee: Ericsson GE Mobile Communications Inc., Paramus, N.J.
[21] Appl. No.: 222,008
[22] Filed: Apr. 4,1994
Related U.S. Application Data
[63] Continuation of Ser. No. 867,149, Apr. 10, 1992.
[51] Int. CL« H04J 13/04; H04B 7/216
[52] U.S. CI 375/200; 455/54.2;
455/70
[58] Field of Search 375/1; 455/70, 54.2
[56] References Cited
U.S. PATENT DOCUMENTS
4,222,115 9/1980 Cooper et al 375/1
4,435,840 3/1984 Kojima et al 455/33
4,485,486 11/1984 Webbetal 455/54.2
4,613,990 9/1986 Halpern 455/33
4,677,687 6/1987 Matsuo 455/10
4,694,467 9/1987 Mui 375/1
4,696,027 9/1987 Bonta 379/60
4,811,421 3/1989 Havel et al 455/67.1 X
4,870,698 9/1989 Katsuyama et al 455/67.1
4,984,247 1/1991 Kaufmann et al 375/1
5,056,109 10/1991 Gilhousen et al 375/1
5,151,919 9/1992 Dent 375/1
The present invention includes a system and method for minimizing interference between two radio stations, e.g., a mobile radio telephone and a fixed base station, at the initiation of a radio communication. A mobile station initiates a random access at the lowest power level and increases the transmission power level until the base station detects the access signal. Once detected, the power level of the message is maintained at the detected level so that the signal interference is avoided. The present invention also provides a mechanism for synchronizing random access communications between mobile stations and the base station despite variation in distances between the mobile and base stations.
43 Claims, 6 Drawing Sheets
JO
