WO2001026407A1

WO2001026407A1 - Method and apparatus for paging and responding to pages in a mobile radio communications system

Info

Publication number: WO2001026407A1
Application number: PCT/SE2000/001813
Authority: WO
Inventors: Per Beming; Ingrid Nordstrand; Walter Müller; Håkan Palm; Pontus Wallentin
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 1999-10-06
Filing date: 2000-09-19
Publication date: 2001-04-12
Also published as: MXPA02003418A; DE60035206T2; CN1231088C; CN1408191A; EP1219132A1; DE60035206D1; AU770884B2; TW494695B; EP1219132B1; ATE364972T1; JP2003511927A; JP4680460B2; US6628942B1; AU7975800A; ES2287035T3; AR032602A1

Abstract

A paging origination identifier associated with an origination of a page to a mobile radio terminal is included with a mobile terminal's response to the page. For example, assuming that the page to the mobile terminal is in a first area, the mobile terminal responds to the page from a second area and includes the identifier in that response. The second area may be a cell controlled by another radio network control node, another radio network operator, or even another type of cellular system. The identifier is used to route the page response through the radio network ultimately to the paging originator. The identifier may be, for example, a paging area identifier, a registration area identifier, or a network exchange identifier. Another example identifier is the cell where the mobile terminal received the page. Cell evaluation and selection processes need only be performed while the mobile terminal is listening to the paging channel, for example, thereby saving mobile terminal battery life. Since the mobile terminal checks for an optimum cell just before it transmits a paging response, it ensures that the optimum cell is used, thereby improving the quality of the communication. As a result, there is less chance of increased interference caused by the uplink transmission, of a lost connection, or of an error in the message.

Description

METHOD AND APPARATUS FOR PAGING AND RESPONDING TO PAGES IN A MOBILE RADIO COMMUNICATIONS SYSTEM

RELATED APPLICATIONS

This patent application is related to commonly assigned U S Patent Application Serial No 09/071,886, filed May 5, 1998, entided "Multicell Area Pagmg for Cellular Communication System" and U.S. Patent Application Serial No. 09/258,151, filed February 26, 1999, and entided "Method and Apparatus for Transferring Information Between Mobile Terminals and Entities in a Radio Access Network." These disclosures are lncorp orated herein by reference.

FIELD OF THE INVENTION

The present mvention finds application to cellular communications and relates to mobile terminal responses to pages in a mobile communications system

BACKGROUND OF THE INVENTION

A cellular telephone is one example of what is generally characterized as a "mobile station" (MS), a "mobile terminal" (MT), or even more generally as "user equipment" (UE). The term mobile terminal is employed hereafter for purposes of description. Telecommunications services are provided between a cellular telecommunications network and a mobile terminal over an air interface, e g., over radio frequencies. An active mobile terminal communicates over the air interface with one or more base stations. The base stations are managed by base station controllers (BSCs), which in some systems, are known as radio network controllers (RNCs). The term RNC is employed hereafter for purposes of description. Radio network controllers are coupled to one or more telecommunications networks by way of one or more control nodes such as a mobile switching center (MSC) node for connecting to connection-oriented, circuit- switched networks such as PSTN and/or ISDN, and a general packet radio service (e.g , GPRS) node for connectmg to connectionless, packet-switched networks such as the Internet

A simplified cellular communications system is shown in function block format m Fig 1 An example core network is connected to several radio network controlleis (RNC) mcludmg RNCl, RNC2, and RNC3 Each RNC controls the allocation of radio resources and radio connectivity operations for a set of cells RNCl controls cells 1 1-1 5, RNC2 contiols cells 2 1-2 5, and RNC3 controls cells 3 1-3 5 The RNCs communicate by way of a signaling network, e g , signaling system number 7 (SS7), and a transport network Each cell is a geographical area where radio coverage is provided by radio base station equipment at the base station site A base station may serve one or more cells A "handover" occurs as a mobile terminal travels from an old cell to a new cell which permits mobile terminals to "roam" considerable distances Each cell is identified usmg a unique identity broadcast in that cell over a common broadcast channel

As indicated in Fig 1, the RNCs, the interconnecting signaling and transport network, and the radio base station equipment in each of the cells together comprise a radio access network (RAN) Mobile terminals (MTs) permit a subscriber access to telecommunications services offered by the core network via the RAN The radio access network controls radio connections and transmissions between the core network and the mobile terminals

Different roles may be assigned to RNCs in the RAN depending on circumstances, configurations, etc One RNC role is that of a "controlling" RNC (CRNC) which controls the radio resources in its set of cells In the example shown in Fig 1, the RNCl is the controlling RNC for cells 1 1 to 1 5, the RNC2 is the controlling RNC for cells 2 1 to 2 5, and the RNC3 is the controlling RNC for cells 3 1 to 3 5

Fig 2 shows adjacent cells m a cellular communications network An active cell denotes the cell currendy supporting a radio connection with a mobile terminal Adjacent neighboring cells may be selected by the mobile terminal via forward handover to support the connection Forward handover or cell reselection is a process where a mobile termmal itself contmues an established connection between a core network and the mobile termmal as the mobile terminal moves between different cells in the radio access network Contrasted with traditional handover, the mobile termmal in forward handover mdependendy re-establishes the radio connection with a new cell. This re-establishment of the connection is performed without prior notification via the old cell. Nor is there advance preparation in the network to continue the communication via the new cell. It is the mobile termmal that initiates and orchestrates forward handover rather than the core network, the core network node (e.g., an MSC), or the radio access network (RAN).

Fig. 3 illustrates an example where cells controlled by RNC1-RNC3 are grouped into registration areas, RA1-RA6, each consistmg of one or several cells. Information transmitted on the broadcast channel m each cell may contain cell and registration area identifiers for purposes of registration control. As long as such cell and registration area identifiers broadcast by a specific cell contain the same cell and registration area identifiers assigned to the mobile terminal during the most recent cell or RA update procedure, the mobile termmal need not register. However, when the termmal mobile terminal does not recognize the broadcast cell and registration area identifiers in the cell, it initiates an RA update procedure

To reach a mobile termmal, the radio network initiates a pagmg procedure. More specifically, a pagmg message containing the mobile termmal identity is transmit on a pagmg channel. In order for the pagmg message to be directed to an area where the mobile termmal is located, the radio network stores in memory determines the current location of the mobile station either on a cell level, on a registration area level, or on some other level. The page is then transmitted m a pagmg area which may, for example (although not necessarily), be identical to the registration cell or a registration area. Another example pagmg area may correspond to cells 1:1-1:5 associated with RNCl as shown m Fig.l.

When the mobile termmal listens to the pagmg channel m its current cell, it may be decide to change to another cell using a cell res election process as a result of changed radio conditions More specifically, another cell may have better, current radio conditions for communication for that mobile terminal The cell reselection may be decided based on one or more cell selection evaluation criteria For example in a CDMA based system, the mobile termmal listening for pages need only be concerned about the quality of the downlmk transmission from the base station in the current cell On the other hand, if the mobile termmal must respond to the page, it must consider the uplmk radio conditions over which it must transmit m that cell The uplmk conditions may not be optimal, meanmg that the mobile would have to transmit at a higher power than it would from a more optimal cell In this example, the mobile may select the more optimum cell before it transmits a response to the page If the mobile termmal changes its current cell, the new cell may belong to a new registration area Normally, this would tπgger a registration procedure

Balancing the desire to select the most optimal cell, e g , to find and select the cell with the best uplmk and downlmk radio conditions, is the need to conserve battery power of the mobile terminal Therefore, the mobile termmal may limit cell selection evaluation to certain time periods such as only when the mobile termmal is listening to the paging channel Otherwise, the mobile termmal must use precious battery power to perform the cell reselection evaluation process at another time separate from the time it is powered up to listen to the pagmg channel

The mobile termmal responds to a page by sendmg a pagmg response message to the radio network Traditionally, the mobile termmal responds to the pagmg message in the same cell where it received that pagmg message However, because the mobile termmal is listening to the pagmg channel, it may also be evaluating whether the current cell is the optimum cell, e g , for uplmk transmission m response to the page m a CDMA -based system, before respondmg to the page If the mobile termmal happens to select another, more optimum cell and send a pagmg response message to that new cell, that message may not be routed to the pagmg originator For example, if the newly selected cell belongs to a different RNC than the RNC that oπgmated the page, the pagmg response may not find its way back to the page originating RNC or the page originating, external core network Furthermore, the new cell might belong to another network operator, or even another type of cellular system, e g , GSM instead of wideband CDMA The result is a significant number of "unsolicited" pagmg responses that are not recognized by the receivmg radio network control node, and therefore, are not directed to the pagmg originator In second generation mobile communication systems, such as

GSM, this situation is avoided by prohibiting a mobile termmal from respondmg to a page from a cell outside the registration area where it is registered But this prohibition gready restricts the flexibility and coverage area of the radio network

It is similarly possible to constram the mobile termmal so that it only responds to the page m the cell where it received the page However, the mobile termmal may be forced to remain on a non-optimal cell with poor radio conditions, possibly resulting m erroneously received or transmitted messages The mobile terminal would need to monitor the uplink and downlmk conditions of its current and neighboring cells to determine and select the optimum cell at times other than when receivmg a page This may be acceptable if such evaluations occur frequendy, but at the cost of mcreased battery loss at the mobile termmal resulting from those frequent evaluations Furthermore, even with mcreased evaluation periods, the radio conditions may be changing rapidly so that there is a possibility that the radio conditions may have changed for the worse by the time the mobile termmal is listening/responding to a page

The present mvention solves these problems by providing a mechanism to efficientiy and reliably route a pagmg response from a mobile termmal to the page originator— even if the mobile termmal has selected a new, more optimum cell just before respondmg to the page As a result, the cell evaluation and selection process need only be performed while the mobile is listening to the pagmg channel, thereby savmg mobile termmal battery life Smce the mobile termmal checks for the optimum cell just before it transmits a pagmg response, there is less chance of mcreased mterference caused by the uplmk transmission, of a lost connection, or of an error m the message

A pagmg origination identifier is associated with an origination of a page to a mobile radio termmal. The mobile termmal responds to the page usmg the identifier. For example, assummg that the page to the mobile termmal is m a first area, the mobile termmal responds to the page from a second area and mcludes the identifier m that response The pagmg response may be part of an initial random access message or mcluded with a pagmg access message sent by the mobile termmal after a connection is made with the radio network. The identifier is used to route the page response through the radio network ultimately to the pagmg originator. Various example routing embodiments usmg the identifier in a pagmg response from the mobile terminal are described below The identifier may be for example a pagmg area identifier, a registration area identifier, or a network exchange identifier and may be mcluded m the page.

Alternatively, the identifier need not be mcluded with the page. An example identifier in this situation is the cell identity where the mobile terminal received the page.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregomg and other objects, features, and advantages of the mvention will be apparent from the following description of preferred example embodiments as well as illustrated in the accompanymg drawings m which reference characters refer to the same parts throughout While individual functional blocks are shown m many of the figures, those skilled m the art will appreciate these functions may be performed by individual hardware circuits, by a suitably programmed digital microprocessor or general purpose computer, by an application specific mtegrated circuit (ASIC), and/or by one or more digital signaling processors (DSPs).

Fig. 1 is a simplified function block diagram of a radio communications system with a radio access network;

Fig. 2 is a diagram lllustratmg conceptually a cellular radio network identifying active cells surrounded by neighbormg cells;

Fig. 3 illustrates example registration areas; Fig. 4 is a function block diagram of a mobile communications system mcludmg both a wideband CDMA -based universal mobile telephone system (UMTS) and a Global System for Mobile Communication system (GSM);

Fig 5 is a function block diagram of an RNC and a base station shown m

Fig 6 is function block diagram of a mobile termmal shown m Fig. 4;

Fig 7 is a flowchart diagram lllustratmg a Page Response m Neighbor Cell procedure m accordance with one example embodiment of the present mvention;

Figs 8A-8D illustrate example simplified formats for a pagmg message, an initial random access message, and a pagmg response message, respectively, mcorporatmg a pagmg origination identifier;

Fig 9 illustrates an example, non-hmitmg page/page response scenario m which the present mvention is employed;

Figs. 10 and 11 are signaling diagrams lllustratmg different example implementations of the mvention in accordance with the example page/page response scenario of Fig. 9;

Fig 12 is another example, non-limiting page/page response scenario m which the present mvention is employed;

Fig. 13 illustrates four (A-D) signaling diagrams of different example implementations of the mvention in accordance with the example shown m Fig. 12; and

Fig 14 is yet another example, non-limitmg page/page response scenario m which the present mvention is employed. DETAILED DESCRIPTION OF THE DRAWINGS

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular embodiments, network architectures, signaling flows, protocols, techniques, etc., in order to provide an understandmg of the present mvention However, it will be apparent to one skilled m the art that the present mvention may be practiced in other embodiments that depart from these specific details. For example, the present mvention is sometimes disclosed m the example context of radio access networks having radio network control node a wideband-CDMA based mobile radio communications system. However, those skilled m the art will appreciate the present mvention can be apphed to other types of mobile radio systems and radio networks In other instances, detailed descriptions of well-known methods, mterfaces, devices, protocols, and signaling techniques are omitted so as not to obscure the descπption of the present mvention with unnecessary detail.

The present mvention may be applied in any mobile communications system mcludmg that shown m Fig. 1 described earlier. Another non-limitmg example is the mobile communications system shown m Fig 4 now described A representative, circuit- switched, external core network, shown as a cloud 12 may be for example the public switched telephone network (PSTN) and/or the mtegrated services digital network (ISDN) Another circuit-switched, external core network may correspond to another Public Land Mobile radio Network (PLMN) 13. A representative, packet-switched, external core network shown as cloud 14 may be for example an IP network such as the Internet. The core networks are coupled to corresponding network service nodes 16 The PSTN /ISDN network 12 and other PLMN network 13 are connected to a circuit- switched core node (CSCN), such as a Mobile Switching Center (MSC), that provides circuit- switched services.

Each of the core network service nodes 18 and 20 is part of an existmg second generation type of mobile communications system like the Global System for Mobile Communications (GSM) In GSM, the MSC 18 is connected over an mterface A to a GSM base station subsystem (BSS) 22 which in turn is connected to a radio base station 23 over an mterface A'. The packet-switched network 14 is connected to a packet- switched core node (PSCN), e.g , a GSM Packet Radio Service (GPRS) node 20 tailored to provide packet-switched type services in the context of GSM which is sometimes referred to as the Servmg GPRS Service Node (SGSN). The GPRS node is connected to the GSM BSS 22 over an mterface Gb

Each of the core network service nodes 18 and 20 is also part of a third generation, Universal Mobile Telecommunications System (UMTS). In UMTS, the core network service nodes 18 and 20 are coupled to a UMTS terrestrial radio access network (UTRAN) 24 over a radio access network mterface. The UTRAN 24 mcludes one or more radio network systems (RNS) 25 each with a radio network controller (RNC) 26 coupled to a plurality of base stations (BS) 28 and to the RNCs m the UTRAN 24.

Radio access over GSM is based upon the well known time division multiple access (TDMA) principle where time slot channels are time multiplexed on various frequencies. Radio access over the UMTS radio mterface is based upon wideband, Code Division Multiple Access (WCDMA) with individual radio channels allocated usmg CDMA channelization or spreading codes. Of course, other access methods may be employed. WCDMA provides wide bandwidth for multimedia services and other high transmission rate demands as well as robust features like diversity handoff and RAKE receivers to ensure high quality communication service m a frequendy changing environment. Each mobile station is assigned its own scramblmg code in order for a base station 28 to identify transmissions from that particular mobile station. The mobile station also uses its own scramblmg code to identify transmissions from the base station either on a general broadcast or common channel or transmissions specifically mtended for that mobile station. That scramblmg code distinguishes the scrambled signal from all of the other transmissions and noise present m the same area.

Different types of control channels are shown bridging the radio mterface For example, in the forward or downlmk direction, there are several types of broadcast channels mcludmg a general broadcast channel (BCH), a paging channel (PCH), and a forward access channel (EACH) for providing various types of control messages to mobile stations In the reverse or uplmk direction, a random access channel (RACH) is employed by mobile stations whenever access is desired to perform location registration, call origination, page response, and other types of access operations.

Simplified function block diagrams of the radio network controller 26 and base station 28 are shown m Fig. 5. The radio network controller 26 mcludes a memory 50 coupled to data processmg circuitry 52 that performs numerous radio and data processmg operations required to perform its control function and conduct communications between the RNC and other entities such as the core network service nodes, other RNCs, and base stations. Data processmg circuitry 52 may mclude any one or a combmation of suitably programmed or configured general purpose computer, microprocessor, microcontroller, dedicated logic circuitry, DSP, ASIC, etc., as described above. The base station 28 mcludes a data processmg and control unit 54 which, m addition to performing processmg operations relatmg to communications with the RNC 26, performs a number of measurement and control operations associated with base station radio equipment mcludmg transceivers 56 connected to one or more antennas 58.

A simplified function block diagram of a mobile station 30 is shown m Fig. 5. The mobile station 30 mcludes an antenna 74 for transmittmg signals to and for receivmg signals from a base station 28. The antenna 74 is coupled to radio transceivmg circuitry mcludmg a modulator 70 coupled to a transmitter 72 and a demodulator 76 coupled to a receiver 80. The radio transceived signals mclude signaling mformation m accordance with an air mterface standard(s) applicable to the GSM and wideband CDMA systems shown m Fig. 4. The data processmg and control unit 60 and memory 62 mclude the circuitry required for rmplementmg audio, logic, and control functions of the mobile station. Memory 62 stores both programs and data Conventional speaker or earphone 82, microphone 84, keypad 66, and display 64 are coupled to the data processmg and control unit 60 to make up the user mterface A battery 68 powers the various αrcuits required to operate the mobile station One example implementation of the mvention is now described usmg the flow chart diagram shown m Fig. 7 identified as Page Response m Neighbor Cell (block 100) Initially, a mobile terminal is paged rn a current cell(s) or area(s) where the mobile is believed to be located (block 102). An identifier, sometimes called a paging origination identifier, is associated with the page and may be mcluded or not mcluded with the page (block 102). The identifier is associated with the originator of the page and can identify some point, port, node, or address m the radio access network where the page originated, for example In block 106, the mobile terminal evaluates if any neighbormg cells is more optimal than the current servmg cell. If so, the mobile termmal selects that more optimal cell. The mobile termmal identified m the page responds, (e.g., from anywhere m the radio access network), to the radio access network usmg the identifier (block 108). If the mobile termmal selected a more optimal neighbormg cell, the page response would be transmitted from that newly selected cell rather than from the cell which the page was received.

The radio access network detects the identifier and uses it to route the pagmg response of the mobile termmal to the originator of the page, e.g., to the pomt, port, node, or address m the radio access network where the page originated (block 110). In this way, if the mobile termmal responds to the page from a neighbor cell that is now more optimum than the cell m which the page was received by the mobile termmal, the radio access network(s) ιs(are) nevertheless able to properly route the pagmg response by virtue of the identifier. Indeed, the neighbormg cells may mclude cells belongmg to other RNCs, other cellular operators, or even other types of radio access systems For example, when the mobile termmal receives the page via a WCDMA/UTRAN cell, it may be more optimal to respond m a GSM cell.

Figs. 8A-8D show non-limiting, example, simplified signal formats that may be used m pagmg messages and pagmg responses from the mobile termmal. Fig. 8A illustrates a simplified portion of a pagmg message mcludmg a mobile termmal identifier (MT ID) field as well as a pagmg origination identifier field. The MT ID is used withm the pagmg originator node to associate the page response with the page The pagmg origmation identifier could be a pagmg area identity, a registration area identity, or an RNC identifier or address

As an alternative to mcludmg the pagmg origination identifier m the page message, a cell ID corresponding to the cell where the mobile termmal received the page may be used as the pagmg origmation identifier Smce the cell ID is broadcast to all mobile terminals m the cell over the cell's broadcast channel, there is no need to mclude the cell ID in the pagmg message thereby simplifying implementation of the mvention m existing s₎ stems smce the format of the pagmg message need not be altered

In any pagmg response signal from the mobile termmal, the pagmg origmation identifier received m the page is mcluded and used by radio network to route the pagmg response to the paging originator Fig 8B illustrates a non-limitmg example where the pagmg response is mcluded m an initial random access message before a connection is established between the mobile terminal and the radio network The mobile termmal mcludes the pagmg ongination identifier received m the page or some other broadcast message from the radio network m addition to the usual fields such as an MT ID field The initial random access message may be received by a base station associated with an RNC A different from the RNC B controlling the base station that transmitted the page received by the mobile terminal In that case, the contents of the initial random access message are forwarded to the RNC B by RNC A usmg the pagmg origmation identifier In this example, the responsibility of the connection with the mobile termmal is the RNC B that transmitted the page to the mobile termmal

The initial random access message may mclude the cell ID as well as the usual fields such as MT ID as shown in Fig 8C The cell ID refers to the cell where the mobile termmal received the page The initial random access message may be received by a base station associated with an RNC A different from the RNC B controlling the base station that transmitted the page received by the mobile termmal In that case, the contents of the initial random access message are forwarded to the RNC B by RNC A usmg the cell ID Another example, non-limitrng pagmg response format is a pagmg response message shown in Fig. 8D transmitted by the mobile station after a connection is established between the mobile termmal and an RNC associated with the cell m which the mobile termmal responds. In other words, the mobile termmal does not mclude the paging origmation identifier m the initial random access message sent back to the radio network Instead, the initial random access and the connection to the mobile termmal are handled by the RNC associated with the base station receivmg the initial random access message, which is not necessarily the same RNC that sent the page When the connection with the mobile terminal is established, the mobile termmal sends a pagmg response message that mcludes the paging origmation identifier This pagmg response message is then forwarded to the RNC that sent the page.

Fig 9 illustrates an example application of the present mvention to a scenario where the mobile termmal is at or near the border between cell 1 5 and cell 2:1. Cell 1.5 is controlled by RNC 1, and cell 2:1 is controlled by RNC 2 The two RNCs are coupled together by way of a lmk b The mobile termmal MT is paged m all of the cells 1 1-1.5 controlled by RNC 1. So the RNC 1 is associated with the oπgmation of the page. However, the mobile termmal responds to the page m cell 2 1 In this non-limiting example, the address of the RNC 1 is mcluded m the page and serves as the pagmg origmation identifier As a result of that mcluded pagmg origmation identifier, the pagmg response m the initial random access message to cell 2-l is routed to the RNC 1 via lmk b Fig 10 illustrates a simplified signaling diagram where the page is sent to the mobile termmal from RNC 1 to the MT via cell 1:5. The MT sends its response m the initial random access (RA) message to cell 2T forwarded to RNC 2 which re-routes that message to RNC 1 Instead of mcludmg a pagmg response m the mitial random access message like that shown m Fig 10, the mobile termmal may mclude the cell ID of the cell where the mobile termmal received the page message m the mitial random access message. In this case, the mitial random access message is routed to RNC 1 via RNC 2 usmg the cell ID

Alternatively, if the mobile terminal does not mclude the paging origmation identifier m the mitial random access message, a connection is established between RNC 2 and the mobile termmal When the connection to the mobile termmal is established, the mobile termmal sends a pagmg response message mcludmg the paging origmation identifier identifymg RNC 1 Consequentiy, RNC 2 forwards the pagmg response message to RNC 1 via lmk b Fig. 11 is a simplified signaling diagram for this alternate, example implementation

The mvention is readily applied to more complicated routmg scenarios. Consider the example illustrated m Fig. 12. Three RNCs are shown with adjacent RNCs communicatmg via lmks b and c. RNC 1 controls cells 1:1-1 5; RNC 2 controls cells 2:1- 2:5; and RNC 3 controls cells 3 1-3:5. Both RNCs 1 and 2 are coupled to an external core network node, which m this example, is MSC 1 via lmks a and f, respectively. RNC 3 is coupled via lmk e to another external core network node, which m this example, is MSC 2. The MSCs are coupled together by lmk d. The mobile termmal is located at or near the border of cells 2:5 and 3:1

The page originates from MSC 1, and the mobile termmal is paged m cells 1:1-2:5 While the mobile termmal receives the page m cell 2:5, it responds m cell 3:1.

Four example alternatives are illustrated m the simplified signaling diagrams A-D shown m Fig. 13. In diagram A, the pagmg origmation identifier identifies RNC 2. The page response from the mobile termmal m the mitial random access message to cell 3.1 mcludes the RNC 2 identifier. RNC 3 receives that message and re-routes it to RNC 2 via lmk c. The RNC 2 then forwards the page response via lmk f to MSC 1.

Alternatively, the page message may not mclude a pagmg origmation address. Instead, the mobile termmal mcludes the cell ID of cell 2:5 m the mitial random access message. The mitial random access message is routed usmg the cell ID to RNC 2, and the connection is established between RNC 2 and the MT. Then the pagmg response message is sent from the mobile termmal usmg the estabhshed connection via RNC 2 to MSC 1.

In diagram B, the mobile termmal does not mclude the pagmg originator address m the mitial random access message. Instead, a connection is established between RNC 3 and the mobile termmal. Thereafter, the mobile termmal sends a paging response message mcludmg the paging origmation identifier (here identifymg RNC 2) to RNC 3. RNC 3 then forwards that message via lmk c to RNC 2, and RNC2 sends the message to MSC 1 via lmk f. This scenario is applicable when the mobile termmal receives a page after a connection to RNC 3 is already established.

In signalmg diagram C, the mobile termmal pagmg response to RNC 3 mcludes a pagmg origmation identifier, which m this example, identifies MSC 1. As the MSC 2 is above RNC 3 m the architecmral hierarchy, the page response is routed via link e to MSC 2. The MSC 2 routes the page response to MSC 1 via link d couplmg the two MSCs. In signalmg diagram D, the pagmg origmation address of the mobile termmal pagmg response again identifies MSC 1. Although MSC 1 is not above RNC 3, a lmk g may be provided to couple MSC 1 and RNC 3 if desired. If this is the case, the page response may then be routed by RNC 3 directly to MSC 1 via lmk g.

In yet another example, non-limitmg application of the mvention illustrated m Fig. 14, the mobile termmal receives a page m a cell belongmg to one type of radio access system, ι.e., a WCDMA based system, m cell 2:5. The mobile termmal then selects a cell 4.1 belongmg to another type of mobile communications system, ι.e., a GSM system, and establishes a connection with the BSC. In this example, a pagmg origination identifier identifies MSC 1. A paging response message mcludmg the pagmg origmation identifier is sent by the mobile termmal on the established connection and is routed to MSC 1 via MSC 2. In this particular example configuration, MSC 2 consults with a node address server (NAS) usmg the pagmg origmation identifier and the MT ID The NAS returns the MSC 1 address which MSC 2 then uses the MSC 1 address to route the pagmg message by way of the signalmg network to MSC 1.

Usmg the pagmg origmation identifier of the mvention m page responses from the mobile termmal offers many advantages First, the inclusion of the pagmg origmation identifier is simple and does not require separate messages, new communication protocols, or extra signalmg Second, smce the mobile termmal does not need to find the optimum cell before it listens to the pagmg channel for pages, the termmal battery power is conserved The mobile termmal can listen for pages in a non-optimum cell and at the same time make the necessary measurements to determine a more optimum cell The pagmg response can be transmitted from a new, more optimum cell which may even be controlled by another operator or another type of cellular system Even if that cell is not m the same hierarchical chain of the non-optimum cell where the page was received, the page response can still be routed reliably back to the originating hierarchical chain Third, and as a result, the number of unsolicited pagmg responses that are not recognized because they are outside of the originating pagmg hierarchy is reduced Fourth, and also as a result, the risk of droppmg a connection durmg the pagmg response procedure is reduced because the mobile termmal is permitted to find the optimum cell at the time of page receipt and page response transmission Fifth, the risk of producmg extra mterference as a result of the higher transmit power level typically required from a non-optimum cell is reduced

While the present mvention has been described m terms of particular examples, those skilled m the art will recognize that the present mvention is not limited to those example described and illustrated herein Different formats, implementations, and adaptations besides those shown and described as well as many modifications, variations, and equivalent arrangements may also be used to implement the mvention Accordmgly, it is mtended that the mvention be limited only by the scope of the claims appended hereto

Claims

WHAT IS CLAIMED IS:

1 In a mobile radio communications system mcludmg a radio network providmg communications services to mobile radio termmals over a radio interface, a method comprising pagmg a mobile termmal m a first area, providmg an identifier associated with an origmation of the page to the mobile terminal, and receivmg a response from the mobile termmal to the page that incorporates identifier.

2. The method m claim 1, wherem the response is received from a second area.

3. The method m claim 1, wherem the identifier identifies a node m the radio network.

4. The method m claim 3, wherem the node is a servmg radio network control node that receives a request to page the mobile termmal from an external network.

5. The method m claim 1, further compπsmg: mcludmg the identifier m the page, wherem the identifier is a pagmg area identifier, a registration area identifier, or a network identifier

6. The method in claim 1, wherem the first area corresponds to a cell, and the identifier is the identity of the cell where the mobile termmal received the page.

7. The method m claim 6, further comprising- broadcastmg the cell identity to all mobile termmals m the cell over a broadcast channel

8. The method m claim 1, wherem the response is part of an mitial random access message.

9 The method m claim 2, wherem the response is a pagmg response message

10 In a mobile radio communications system mcludmg a radio network providmg communications services to mobile radio termmals over a radio mterface, a method comprising: generating a page for a mobile terminal, and providmg to the mobile termmal a pagmg origmation identifier associated with an origin of the page to be used m a response to the page by the mobile terminal

11 The method in claim 10, further compπsmg the mobile termmal transmitting a page response over the radio mterface that mcludes the pagmg origmation identifier.

12 The method m claim 11, further compπsmg the radio network routmg the page response toward an originator of the page usmg the pagmg origmation identifier.

13 The method m claim 11, further compπsmg transmitting the page with the pagmg oπgmation identifier to the mobile termmal m a first cell; receivmg the page response mcludmg the pagmg origination identifier from the mobile termmal from a second cell, and routmg the page message through the radio network toward and originator of the page usmg the pagmg oπgmation address

14 The method m claim 13, wherem the page is transmitted by a first radio network control node associated with a first plurality of cells mcludmg the first cell, and wherem the second cell is one of a second plurality of cells associated with a second radio network control node.

15 The method m claim 14, further compπsmg the mobile termmal respondmg to the page to the second radio network control usmg the pagmg originator identifier, and the second radio network control node detecting the pagmg originator identifier, and as a result, routmg the pagmg response to the first radio network control node

16 The method m claim 14, further comprising establishing a connection between the second radio network control node and the mobile termmal, and transmittmg a pagmg message from the mobile termmal mcludmg the pagmg onginatoi identifier over the connection

17 The method in claim 16, wherem the pagmg message is forwarded to the first radio network control node by the second radio network control node based on the pagmg origmation identifier

18 The method m claim 14, wherem the second radio network control node forwards the pagmg response to a core network node external to the radio network that originated the page

19 The method m claim 14, wherem the second radio network control node forwards the pagmg response to a first external core network associated with the second radio network control node, and wherem the first core network node forwards the pagmg response to a second core network node associated with the page ongmator

20 The method in claim 14, wherem the pagmg origmation identifier is a pagmg area identifier, a registration area identifier, or a network identifier

21 The method m claim 10, wherem the pagmg origmation identifier is the identity of the first cell where the mobile termmal received the page

22 The method m claim 11, wherem the mobile termmal reselects a cell after receivmg the page but before sending a response to the page

23 In a mobile radio communications system mcludmg a radio network providmg communications service with mobile termmals over a radio mterface, a mobile termmal comprising. radio circuitry capable of sending and receivmg information with the radio network over the radio mterface; and data processmg circuitry, coupled to the radio circuitry, configured to detect a page mtended for the mobile termmal, to determine a page origmation identifier, and to send via the radio cuxuitry over the radio mterface to the radio network a response to the page that mcludes the page origmation identifier.

24 The mobile termmal in claim 23, wherem the page contams the page ongmation identifier, the page is detected m a first cell, and the page response is sent to a second cell.

25. The mobile termmal m claim 23, wherem the pagmg ongmator identifier is a pagmg area identifier, a registration area identifier, or a network identifier.

26. The mobile termmal in claim 23, wherem the paging identifier is the identity of the cell m which the page is detected.

27 The mobile termmal m claim 23, wherem the data processmg circuitry is configured to send the page response durmg an mitial random access with the radio network.

28. The mobile termmal in claim 23, wherem detects the page m a first cell and selects a new cell before respondmg to the page.

29. In a mobile radio communications system mcludmg a radio network providmg communications services to mobile termmals over a radio mterface, a radio network control node, comprising- data processmg circuitry configured to provide a pagmg ongmation identifier to a mobile termmal and to generate a page message for the mobile termmal; and radio circuitry, coupled to the data processmg circuitry, for transmittmg the page message over a radio mterface

30 The radio network control node in claim 29, wherem the pagmg ongmation identifier is provided to the mobile termmal with the page message

31 The radio network control node m claim 29, wherem the pagmg oπgmation identifier is provided to the mobile termmal m some fashion other than with the page message

32 The radio network control node m claim 29, wherem the pagmg oπgmation identifier is a cell identification, and the radio circuitry broadcasts the cell identifier to a cell in which the mobile termmal is currently located

33 The radio network control node m claim 29, wherem the pagmg ongmation identifier is a pagmg area identifier, a registration area identifier, a cell identifier, or a network address

34 In a mobile radio communications system mcludmg a radio network providmg communications sen _ce with mobile terminals over a radio mterface, apparams compπsmg means for transmittmg a page m a first set of one or more cells mtended for a mobile terminal, and means for detectmg a page response from the mobile termmal that mcludes a page ongmation address and directing the page response towards an ongmator of the page based on the page ongmation address

35 The apparams m claim 34, wherem the page response from the mobile termmal is received from a cell m a second set of one or more cells

36 The apparams m claim 35, wherem the second set of cells belongs to a different network operator than the first set of cells

37. The apparatus in claim 35, wherem the second set of cells belongs to a different type of mobile communications network than the first set of cells.

38. The apparams m claim 34, wherem the pagmg oπgmation address is a paging area identifier, a registration area identifier, a cell identifier, or a network address.

39 The apparams in claim 34, wherem the pagmg ongmation address pomts to an external network that originated the page

40 The apparams m claim 34, wherem the means for transmitting mcludes the page ongmation address m the transmitted page

41. The apparams m claim 34, wherem the means for transmittmg mcludes the page ongmation address in a broadcast message other than the page.