And then going back to the 261 patent:
patents.ibm.com
US5267261: Mobile station assisted soft handoff in a CDMA
cellular communications system
Inventor(s):
Blakeney, II; Robert D., San Diego, CA
Karmi; Gadi, San Diego, CA
Tiedemann, Jr.; Edward G., San Diego, CA
Weaver, Jr.; Lindsay A., San Diego, CA
Applicant(s):
Qualcomm Incorporated, San Diego, CA
Publication Date:
Nov. 30, 1993
Application Date:
March 5, 1992
Application Number:
US1992000847148
IPC Class (Ed. 5):
H04K 001/00;
US Class:
375/001; 455/033.1; 455/034.1; 455/056.1; 455/034.2; 379/060;
Field of Search:
379-060 ; 375-001 ; 455-33,34,56 ;
Abstract: In a code division multiple access (CDMA) spread spectrum cellular communication
system in which a mobile station user communicates with another system user via at least one base
station, wherein each base station transmits a common pilot signal of a different code phase with
respect to other base stations in said system, a method for directing communications between said
mobile station user and said base stations. The mobile station monitors the signal strength of pilots
and reports the measured signal strength to a system controller via the base station through which it
is communicating. Command messages from the system controller to a new base station and the
mobiles station establishes communication through the new base station in addition to the
communication through the current base station. When the mobile station detects the falling below a
predetermined level of the signal strength of a pilot corresponding to at least one of the base stations
through which the mobile station is communicating, the mobile station reports the measured signal
strength indicative of the corresponding base station to the system controller via the base stations
through which it is communicating. Command messages from the system controller to the identified
base station and the mobiles station terminates communication through the corresponding base
station while communications through the other base station or base stations continue.
We claim:
1. In a code division multiple access (CDMA) spread spectrum cellular communication system in
which a mobile station user communicates with another system user via at least one base station,
wherein each base station transmits a common pilot signal of a different code phase with respect to
other base stations in said system, a method for directing communications between said mobile
station user and said base stations comprising the steps of:
measuring at a mobile station signal strength of base station transmitted pilot signals;
communicating a signal strength message, from said mobile station via at least one base
station said mobile station is in communication with, when at least one measured pilot signal
each corresponding to a base station to which said mobile station is not currently in
communication with, exceeds a first predetermined level;
communicating, from at least one of said base stations said mobile station is in communication
with and each base station corresponding to said mobile station measured pilot signal
exceeding said first predetermined level, a direction message; and
establishing, at said mobile station in response to said direction message, communications
through each base station corresponding to said mobile station measured pilot signal
exceeding said first predetermined level. |
