Multiplex communications – Communication over free space – Signaling for performing battery saving
Reexamination Certificate
1998-10-23
2002-11-12
Hsu, Alpus H. (Department: 2662)
Multiplex communications
Communication over free space
Signaling for performing battery saving
C370S350000, C455S343200, C455S522000, C455S553100, C340S007340, C340S870030
Reexamination Certificate
active
06480476
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to battery-operated mobile radio stations, and more particularly, to balancing the desire to conserve battery power with other factors that effect mobile station performance.
BACKGROUND AND SUMMARY OF THE INVENTION
Mobile communications have developed from first generation, analog-based mobile radio systems to second generation digital systems, such as the European Global System for Mobile communications (GSM). Current developments for a third generation of mobile radio communications are referred to as the Universal Mobile Telephone communications System (UMTS). In simple terms, the UMTS is “communication to everyone, everywhere,” where communication includes the provision of information using different types of media, i.e., multimedia communications. The goal of UMTS services is to combine both fixed and mobile services to form a seamless, end-to-end service for the user.
Because of the widespread success of the existing GSM platform, i.e., a global “GSM-footprint,” as well as the inherent upgradability and modularity of the GSM platform, there is a strong impetus to base the UMTS on an “evolved” GSM platform. Accordingly, the present invention is described in the context of a UMTS based on an evolved GSM platform, and therefore, uses GSM terminology. Of course, the principles of the present invention are not limited to a UMTS, a GSM platform/terminology, or to any specific mobile communications network and may be implemented using other appropriate network platforms and configurations.
Current mobile/cellular telecommunications networks are typically designed to connect and function with Public Switched Telephone Networks (PSTNs) and Integrated Services Digital Networks (ISDNs). Both of these networks are circuit-switched networks—rather than packet-switched—and handle relatively narrow bandwidth traffic. However, packet-switched networks, such as the Internet, are very much in demand and handle much wider bandwidth traffic than circuit-switched networks. While wireline communication terminals, e.g., personal computers, are capable of utilizing the wider packet-switched network bandwidth, wireless mobile radio terminals are at a considerable disadvantage because of the limited bandwidth of the radio/air interface that separates the mobile terminals from packet-switched networks.
There is also a need for a radio access system that provides wireless access at very high data rates and supports enhanced bearer services not realistically attainable with the first and second generation mobile communication systems. This need may be best satisfied by a Wideband-Code Division Multiple Access (W-CDMA) radio access network.
To assist in the following description, a UMTS
10
is now briefly described in conjunction with
FIG. 1. A
representative-connection-oriented, external core network, shown as the cloud
12
, may be for example the Public Switched Telephone Network (PSTN) and/or the Integrated Services Digital Network (ISDN). A representative-connectionless-oriented, external core network, shown as cloud
14
, may be for example the Internet. Both networks
12
and
14
are coupled to corresponding core network (CN) service nodes
16
. The PSTN/ISDN circuit-switched network
12
is connected to a connection-oriented service node shown as a circuit-switched services node
18
which, in a GSM platform, includes a mobile switching center (MSC)
23
and a corresponding visiting location register (VLR)
24
. Also in the existing GSM platform, the circuit-switched services node
18
is connected to a base station system (BSS)
26
which in turn is connected to a radio base station (BS)
28
having a corresponding geographical cell area
34
.
The connectionless-oriented service node is a packet-switched services node
20
tailored to provide packet-switched type services. In the GSM platform, such a node corresponds to one or more of the General Packet Radio Service (GPRS) nodes, e.g., SGSN, GGSN, etc. Each of the core networks
18
and
20
also connects to a home location register (HLR)
22
which stores mobile station identification, subscription, and mobility/location information. Core network service nodes
18
and
20
are also connected to an UMTS radio access network (URAN)
30
which includes one or more radio network controllers (RNC)
32
coupled to one or more base stations
28
, each base station having a corresponding geographical cell area
34
. The radio access network
30
provides services to/from mobile stations
36
over the radio interface to the core network service nodes
18
and
20
without the core networks having to request specific radio resources necessary to provide those services. The UMTS radio access network (URAN)
30
“maps” radio access bearers onto physical radio channels—a task by and large controlled by the radio network controllers
32
. In a W-CDMA system, individual radio channels are allocated using spreading codes. As described above, W-CDMA provides the wide bandwidth for multimedia services and other high rate demands. In addition, it also provides robust features like diversity handoff and RAKE receivers to ensure high communications quality.
When a mobile station is in an idle state, e.g., not involved in a connection with the URAN
30
, the core networks need to be able to locate and communicate with the mobile station. Mobile stations also need to be able to initiate communications with the core networks. Typically, common channels are employed: one on the downlink direction from the base station to the mobile station (a paging channel), and another in the uplink direction from the mobile station to the base station (a random access channel). Periodically, the idle mobile station registers or otherwise makes its presence known to the base station of a particular cell in which it is currently physically located. If the core network service nodes do not know the specific cell where the mobile station is currently located, the core networks service nodes typically know the general location of the mobile station, i.e., a group of cells typically called a location area. Thus, when a call is to be directed from a core network to a mobile station, a paging procedure is performed where a paging message is sent to the mobile station over the downlink paging channel requesting that the mobile station initiate establishment of a connection with the radio access network
30
via the cell where it is currently located.
In order for the mobile station to receive paging messages, it must be “awake,” i.e., powered up, and listening at the appropriate time to the particular control channel over which the specific paging message was transmitted. If the mobile radio is continually powered and always monitoring that paging channel, there is a high probability that it will detect and accurately receive the page. But mobile stations are normally battery operated, and batteries have a limited life before they must be recharged. Continued monitoring of the paging channel therefore dramatically shortens battery life.
Accordingly, it is desirable to eliminate or otherwise minimize battery consumption where practical. The general idea is to place the mobile station into a low power consumption or “sleep” mode to save battery power when the mobile station need not perform any necessary function. In order to make sure that it receives important messages, the mobile station is periodically awakened from its sleep mode to a higher power mode so that it can receive messages such as pages or send periodic updates of its location via a common channel. The basic problem of optimizing the sleep mode is a design tradeoff between a longer sleep mode which conserves the mobile station battery power and a shorter sleep mode which provides greater performance like faster call setup times or shorter data transfer delay in the downlink direction towards the mobile station.
One way to approach this optimization problem is to specify a fixed sleep mode period where all mobile stations experience the same battery consumption dela
Hsu Alpus H.
Nixon & Vanderhye
Qureshi Afsar M.
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