Use of received signal strength indicator (RSSI) and global positioning system (GPS) to reduce power consumption in mobile station

#These teachings relate generally to wireless communication terminals or mobile stations, such as powered cellular telephones, and more specifically relate to techniques to optimize the power consumption of portable, battery powered mobile stations.

#An important aspect of the design and operation of battery powered mobile stations, such as cellular telephones and personal communicators, is the optimization of the power consumption. A direct result of the optimization of the power consumption is an increase in both the standby and talk times of the mobile station between battery recharging operations, both of which are readily experienced by and apparent to the user.

#One significant power consuming operation of mobile stations is a requirement to make measurements of signals received from base stations or base sites of neighboring cells when operating within a currently serving cell. In a typical case the mobile station periodically receives a list of neighboring cells from the serving cell base station and then makes measurements, such as received signal strength measurements for radio channels from the neighboring cells. The results of these signal strength measurements are reported back to the base station of the serving cell. These signal strength measurements are useful in determining candidate cells for handoff and reselection purposes. As can be appreciated, these received signal measurement and reporting operations consume some amount of mobile station power.

#The above set forth and other features of these teachings are made more apparent in the ensuing Detailed Description of the Preferred Embodiments when read in conjunction with the attached Drawings, wherein:

#FIG. 1 is a block diagram of a wireless communication system containing a cellular system and a mobile station having a controller and a GPS subsystem that is suitable for practicing the teachings in accordance with this invention;

#FIGS. 2A and 2B each show an equation that is solved by the mobile station of FIG. 1; and

#Referring first to FIG. 1 there is illustrated a simplified block diagram of an embodiment of a wireless communications system 5 that is suitable for practicing these teachings. The wireless communications system 5 includes at least one mobile station (MS) 100. The MS 100 may be embodied as a handheld cellular telephone, a vehicle-installed cellular telephone, a personal communication device, a personal data assistant (PDA) device having wireless communication capabilities, a wireless communication module installable within or with a computer, such as a PCMCIA or similar type of card or module that is installed during use within a portable data processor, such as a laptop or notebook computer, or even a computer that is wearable by the user. In general, the MS 100 may be any device capable of bidirectional communication with a wireless network.

#FIG. 1 also shows an exemplary network operator or cellular system 10 having, for example, a GPRS Support Node (GSN) 30 for connecting to a telecommunications network, such as a Public Packet Data Network or PDN. The GPRS, or General Packet Radio Service, is a GSM phase 2+ service in which radio resources for data transfer are allocated on a per block basis, as opposed to a circuit-switched basis. The network operator 10 also includes at least one base station controller (BSC) 40, as well as a plurality of base stations or base transceiver stations (BTS) 50 that transmit in a forward or downlink direction both physical and logical channels to the mobile station 100 in accordance with the predetermined air interface standard. A reverse or uplink communication path also exists from the mobile station 100 to the network operator, and conveys mobile originated access requests and traffic.

#Each BTS 50 is assumed to support a cell. The BTS 50 through which the MS 100 is currently receiving service is considered to be the serving cell BTS, while at least one other BTS 50 is assumed to be supporting a neighboring or adjacent cell from which the MS 100 is required to periodically make RF signal measurements, as was described above.