HK1187758A - A method for use in a wireless transmit/receive unit (wtru) - Google Patents

Abstract

The present invention discloses a method for use in a wireless transmit/receive unit (WTRU), the method comprising: transmitting a request message to an access network to request information regarding the access networks; receiving a response message from the access network that is responsive to the request message, the response message including handoff policy information related to access networks of two or more technology types; initiating a handoff to a selected target access network of the access networks in the response message based on the handoff policy.

Description

Method for use in a wireless transmit/receive unit (WTRU)

The application is a divisional application of Chinese patent application with the application number of 200680017165.3, the application date of 2006 of 5/16, and the name of 'method and device for implementing handover between wireless access networks configured according to different wireless access technologies'.

Technical Field

The present invention relates to wireless communication systems. More particularly, the present invention relates to a method and apparatus for performing a handover between Radio Access Networks (RANs) that are configured according to different radio access technologies.

Background

Today, there are many different types of wireless access systems providing different types of services, including, for example, Wireless Local Area Networks (WLANs), such as IEEE802 based networks, and cellular networks, such as universal mobile telecommunications system (UMT) terrestrial radio access network (UTRAN), evolved UTRAN (E-UTRAN), GPRS/EDGE radio access network (GERAN), etc., each of which is well developed and provides specific applications.

With the widespread adoption of wireless communication networks in businesses, homes, and public areas, there is a need to support continuous connectivity as users move from one network to another. In order to achieve an "always-on" situation, a wireless transmit/receive unit (WTRU) (i.e., a Mobile Station (MS)) needs to support multiple different networks. Therefore, a seamless handover between these networks is required.

Disclosure of Invention

The present invention relates to a method and apparatus for performing handover between RANs, which are configured according to different RATs. A WTRU is equipped with at least two radio units to support the RAT. Each RAN sends a list of RANs co-located in the RAN coverage area to the WTRU. The WTRU stores the list and determines whether one of the co-located RANs meets handover criteria. The WTRU then initiates a handover from the current RAN to the target RAN if the target RAN meets the handover criteria. Alternatively, the WTRU sends a measurement report to the current RAN, whereby the current RAN determines whether the selected co-located RAN meets handover criteria and initiates a handover to the selected RAN if the handover criteria are met.

Drawings

The invention will be understood in more detail from the following description of a preferred embodiment, given as an example, and with reference to the accompanying drawings, in which:

fig. 1 illustrates a handover procedure in a wireless communication system configured in accordance with the present invention;

FIG. 2 is a signaling diagram of a WTRU-initiated handover procedure from an E-UTRAN to an I-WLAN based on location based, in accordance with the present invention;

FIG. 3 is a signaling diagram of a WTRU-initiated handover procedure from an E-UTRAN to an I-WLAN based on power, in accordance with the present invention;

FIG. 4 is a signaling diagram of a WTRU-initiated, non-broadcast, power-based handover procedure from an E-UTRAN to an I-WLAN, in accordance with the present invention;

figure 5 is a signaling diagram of a WTRU-initiated handover procedure from an E-UTRAN to an I-WLAN, in accordance with the present invention;

figure 6 is a signaling diagram of a WTRU-initiated handover procedure from an I-WLAN to an E-UTRAN, in accordance with the present invention; and

FIG. 7 is a signaling diagram of a power-based E-UTRAN-initiated handover procedure from an I-WLAN to an E-UTRAN, which is implemented in accordance with the present invention.

Detailed Description

When referred to hereafter, a "wtru" includes but is not limited to a user equipment, a mobile station, a fixed or mobile subscriber unit, a pager, or any other device capable of use in a wireless environment.

The features of the present invention may be integrated within an Integrated Circuit (IC) or may be configured in a circuit comprising a multitude of interconnecting components.

Fig. 1 illustrates a handover procedure in a wireless communication system 100 including a plurality of RANs 110a, 110b and a core network 120, the RANs 110a, 110b being configured according to different RATs, and the core network 120 being an all-IP network (AIPN). The core network 120 is connected to other networks, such as a Public Switched Telephone Network (PSTN) 130, the internet 140, and so on. Each of the RANs 110a, 110b may be a Generic Access Network (GAN), GERAN, UTRAN, E-UTRAN, IEEE-based interactive WLAN (I-WLAN), or any other type of radio access network.

For optimal mobility between the different RANs 110a, 110b, the core network 120 provides an open interface to the Mobility Management (MM) 122 that allows an operator of the core network 120 to direct the WTRU150 to the most appropriate RAN110a, 110 b. The core network 120 also provides open interfaces that allow the WTRU150 access to other AIPN services, such as Session Control (SC) 124, authentication, authorization, and accounting (AAA) 126, and policy control 128.

WTRU150 is a multi-mode WTRU equipped with at least two radio units configured to support communication of at least two different RATs. For example, the WTRU150 may include one radio of an E-UTRAN and another radio of an I-WLAN. The WTRU150 establishes a connection with one of the RANs and may perform a handover action to the target RAN if the target RAN meets handover criteria.

The switching may be initiated manually or automatically. If a handover procedure is manually initiated by the user of the WTRU150, the user knows that another RAT exists in his current location and may handover in between. And an auto-initiated handover procedure may be initiated by the WTRU150, or the RAN110a, 110b, or the core network 120.

In terms of WTRU-initiated handover, the WTRU150 detects the presence of another RAT and initiates a handover procedure according to the preferences of the user of the WTRU 150. The WTRU150 receives the necessary information (e.g., handover policy, resource status, etc.) from the network (i.e., the RAN110b or the core network 120). The WTRU150 tracks the location of the coverage area of the RAN110a, 110b and initiates the handover procedure based on predetermined handover criteria.

In system-initiated handover, the core network 120 (or the RAN110a, 110 b) recognizes that the WTRU150 may support multiple RATs and requests the WTRU150 for the necessary information (such as power measurements). The core network 120 (or the RANs 110a, 110 b) keep track of the location of the WTRU150 and initiate the handover procedure upon the WTRU150 entering the coverage area of a target RAN based on a set of criteria, such as mobility of the WTRU150, requested bandwidth, applications, load balancing, user profile, measurement reports provided by the WTRU150, and the like.

An operator may provide (optionally upon WTRU request) the WTRU with inter-access network information regarding regionally-efficient third generation partnership project (3 GPP) and non-third generation partnership project access technologies. The inter-access network information may include operator preferences based on regionally efficient third generation partnership project (3 GPP) and non-third generation partnership project access technologies, and the information may be limited to access technologies and/or networks used by the wtru based on capabilities and/or subscriptions of the wtru.

The invention will be described below in terms of E-UTRAN and IEEE-based I-WLAN, however it should be noted that the invention is also applicable to any form of RAN using any form of RAT.

Figure 2 is a signaling diagram of a WTRU-initiated handover procedure 200 from the E-UTRAN160 to the I-WLAN170 based on location, implemented in accordance with the present invention. The WTRU150 is currently attached to the E-UTRAN160 and listens to E-UTRAN channels such as the Broadcast Control Channel (BCCH) (step 202). The E-UTRAN160 sends (i.e., broadcasts, multicasts, or unicasts) a list of RANs (e.g., I-WLAN, UTRAN, GERAN, or GAN) that are valid within the coverage area of the E-UTRAN160 (step 204). The WTRU150 receives the list and stores the list (step 206). The WTRU150 then sends a request to the E-UTRAN160 for the location of the RAN's service area in the list (step 208). The E-UTRAN160 then retrieves the location information and sends it to the WTRU150 (step 210). The list may contain information about the location of the service area, the radio technologies used by the RANs in the list, supported frequencies, and data rates, among other things.

The WTRU150 constantly monitors its location as the WTRU150 moves around the coverage area of the E-UTRAN 160. The WTRU150 triggers a handover procedure if its location is within the coverage area of another RAN, such as the I-WLAN170 (step 212). If the WTRU150 determines that the WTRU150 is within the coverage area of the I-WLAN170, the WTRU150 sends a message to the I-WLAN170 to initiate a WLAN service (step 214). When the I-WLAN170 receives the message, the I-WLAN170 initiates an authentication procedure to authenticate the WTRU150 and may assign a new IP address based on the interactive situation (step 216). Authentication messages are exchanged between the I-WLAN170 and the E-UTRAN160 (step 218). Once the WTRU150 is authenticated, the I-WLAN170 sends an access grant message to the WTRU150 indicating that it grants access to the WLAN services (step 220). The WTRU150 then initiates a handover procedure to the I-WLAN170 by sending a handover initiation message to the E-UTRAN160 (step 222). Control messages for routing data via the I-WLAN170 are exchanged between the E-UTRAN160 and the I-WLAN170 (step 224). Once a new route is established, the E-UTRAN160 sends a handover complete message to the WTRU150 (step 226) and the services provided to the WTRU150 resume via the I-WLAN170 (step 228).

The procedure 200 is applicable to any form of inter-RAN handover. For example, the process 200 may be used for handover from a UTRAN to an I-WLAN, in which case the UTRAN sends a list of active RANs in the UTRAN's coverage area and the WTRU uses the list to trigger a handover from the UTRAN to the I-WLAN based on the location of the WTRU and the I-WLAN.

Figure 3 is a signaling diagram of a WTRU-initiated handover procedure 300 from the E-UTRAN160 to the I-WLAN170 based on power class, implemented in accordance with the present invention. The WTRU150 includes an E-UTRAN radio 152, a WLAN radio 154, and a handover controller 156 such that the WTRU150 may handover between the E-UTRAN160 and the I-WLAN 170. The WTRU150 is currently attached to the E-UTRAN160 and listens to E-UTRAN channels (e.g., BCCH) (step 302). The E-UTRAN160 sends (i.e., broadcasts, multicasts, or unicasts) a list of other RANs (e.g., I-WLAN, UTRAN, GERAN, or GAN) that are active within the coverage area of the E-UTRAN160 (step 304). The E-UTRAN radio unit 152 of the WTRU150 receives the list and stores the list (step 306). The E-UTRAN radio 152 then initializes the WLAN radio 154 (step 308). The list from the E-UTRAN160 preferably includes a list of frequencies for the I-WLAN170 so that the WTRU radio 154 may use the list of frequencies to search for a valid WLAN.

The WLAN radio 154 is then activated and listens to the WLAN channel based on the frequency list and measures the power level of the signal received by the I-WLAN170 (step 310). If the measured power level meets the predetermined threshold, the handover controller 156 triggers a handover procedure (step 312). The WTRU150 sends a message to the I-WLAN170 to initiate WLAN service (step 314).

When the I-WLAN170 receives the message from the WTRU150, the I-WLAN170 initiates an authentication procedure to authenticate the WTRU150 and may assign a new IP address based on the interactive situation (step 316). Authentication messages are exchanged between the I-WLAN170 and the E-UTRAN160 (step 318). Once the WTRU150 is authenticated, the I-WLAN170 sends an access grant message to the WTRU150 (step 320). The WLAN radio 154 then sends a handover initiation message to the E-UTRAN radio 152 (step 322). The E-UTRAN radio 152 then sends a message to the E-UTRAN160 to initiate a handover to the I-WLAN170 (step 324). Control messages for routing data via the I-WLAN170 are exchanged between the E-UTRAN160 and the I-WLAN170 (step 326). Once a new route is established, the E-UTRAN160 sends a handover complete message to the E-UTRAN radio 152, which is forwarded to the WLAN radio 154 (steps 328, 330). The service is then resumed via the I-WLAN (step 332).

The procedure 300 is applicable to any form of handover between RANs. For example, the process 300 may be used for handover from a UTRAN to an I-WLAN, in which case the UTRAN sends a list of active RANs in the UTRAN's coverage area and the WTRU uses the list to trigger a handover from the UTRAN to the I-WLAN based on measurements of the WTRU and/or the I-WLAN.

Figure 4 is a signaling diagram of a WTRU-initiated handover procedure 400 from the E-UTRAN160 to the I-WLAN170 based on power class and no broadcast, implemented in accordance with the present invention. The WTRU150 includes an E-UTRAN radio 152, a WLAN radio 154, and a handover controller 156. The WTRU150 is currently attached to the E-UTRAN160 and the WLAN radio 154 is in an on state (steps 402, 404). The E-UTRAN radio 152 initializes the WLAN radio 154 for possible handover to the I-WLAN170 (step 406). Since the WTRU150 is not aware of the active RANs in the coverage area of the E-UTRAN160, the WLAN radio 154 monitors the WLAN channels for any active WLAN services (step 408). If the WLAN radio 154 finds any WLAN channel, the WLAN radio 154 locks onto the WLAN channel and measures the power level of the signal passing through the channel (step 410). If the measured power level meets the predetermined threshold, the handover controller 156 triggers a handover procedure and the WTRU150 sends a message to the I-WLAN170 to initiate WLAN service (step 412).

When the I-WLAN170 receives the message, the I-WLAN170 initiates an authentication procedure and may assign a new IP address based on the interactive situation (step 414). Authentication messages are exchanged between the I-WLAN170 and the E-UTRAN160 (step 416). Once the WTRU150 is authenticated, the I-WLAN170 sends an access grant message to the WTRU150 (step 418). The WLAN radio 154 then sends a handover initiation message to the E-UTRAN radio 152 (step 420). The E-UTRAN radio 154 then sends a message to the E-UTRAN160 to initiate a handover to the I-WLAN170 (step 422). Control messages for routing data via the I-WLAN170 are exchanged between the E-UTRAN160 and the I-WLAN170 (step 424). Once a new route is established, the E-UTRAN160 sends a handover complete message to the E-UTRAN radio 152, which is forwarded to the WLAN radio 154 (steps 426, 428). The service is then resumed via the I-WLAN170 (step 430).

The procedure 400 is applicable to any form of handover between RANs. For example, the process 400 may be used for handover from a UTRAN to an I-WLAN, in which case the WTRU monitors an I-WLAN channel and triggers a handover from the UTRAN to the I-WLAN based on measurements of the signals from the UTRAN and/or the I-WLAN.

Figure 5 is a signaling diagram of a WTRU-initiated handover procedure 500 from an I-WLAN170 to an E-UTRAN160, implemented in accordance with the present invention. The WTRU150 includes an E-UTRAN radio 152, a WLAN radio 154, and a handover controller 156. The WTRU150 is currently attached to the I-WLAN170 and listens to the I-WLAN channel (step 502).

The I-WLAN170 sends (i.e., broadcasts, multicasts, or unicasts) a list of other services for the active E-UTRAN within the I-WLAN170 coverage area (step 504). The WTRU150 receives the E-UTRAN list and stores the list (step 506). The WTRU150 may send a request for additional information of the E-UTRAN (step 508). The I-WLAN170 then retrieves the request message and sends it to the WTRU150 (step 510). The additional information includes, but is not limited to, the location of the E-UTRAN, the frequencies supported by the E-UTRAN, and the data rate.

The handover to the E-UTRAN160 may be initiated by the user or automatically by the handover controller 156 based on predetermined criteria, such as signal quality (step 512). If the handover is initiated, the WLAN radio unit 154 sends a radio initialization signal to the E-UTRAN radio unit 152 (step 514). The E-UTRAN radio 152 then initiates an E-UTRAN service initialization procedure that includes attach, registration, context activation, etc. (step 516). The E-UTRAN160 then sends a message to the WTRU150 to grant access to the E-UTRAN160 (step 518). The WLAN radio 154 then sends a message to the I-WLAN170 to initiate handover to the E-UTRAN160 (step 520). Control messages for routing data via the I-WLAN170 are exchanged between the E-UTRAN160 and the I-WLAN170 (step 522). Once a new route is established, the I-WLAN170 sends a handover complete message to the WTRU150 (step 524). The WLAN radio 154 forwards the handover complete message to the E-UTRAN radio 152, which responds with an acknowledgement message (ACK) (steps 526, 528). The WLAN radio 154 is then turned off (step 530) and the service is resumed via the E-UTRAN160 (step 532).

The procedure 500 is applicable to any form of handover between RANs. For example, the process 500 may be used for handover from an I-WLAN to a UTRAN, in which case the I-WLAN sends a list of active RANs within the coverage area of the I-WLAN and the WTRU uses the broadcast list to trigger a handover from the I-WLAN to the UTRAN.

Figure 6 is a signaling diagram of a WTRU-initiated handover procedure 600 for a broadcast-free handover from an I-WLAN170 to an E-UTRAN160, implemented in accordance with the present invention. The WTRU150 includes an E-UTRAN radio 152, a WLAN radio 154, and a handover controller 156. The WTRU150 is currently connected to the I-WLAN 170. The handover to the E-UTRAN160 may be initiated by the user or automatically by the handover controller 156 based on predetermined criteria, such as signal quality (step 602). The WLAN radio 154 sends a signal to the E-UTRAN radio 152 to initialize the E-UTRAN radio 152 (step 604). Since the WTRU150 is not aware of a valid E-UTRAN, the E-UTRAN radio unit 152 searches for the E-UTRAN channel and locks on to the E-UTRAN channel once found (step 606).

The E-UTRAN radio 152 then initiates an E-UTRAN service initialization procedure that includes attach, registration, context activation, etc. (step 608). If the E-UTRAN160 decides to allow the user to be served, the E-UTRAN160 sends a message to the WTRU150 to grant access to the E-UTRAN160 (step 610). The WLAN radio 154 then sends a message to the I-WLAN170 to initiate handover to the E-UTRAN160 (step 612). Control messages for routing data via the I-WLAN170 are exchanged between the E-UTRAN160 and the I-WLAN170 (step 614). Once a new route is established, the I-WLAN170 sends a handover complete message to the WTRU150 (step 616). The WLAN radio 154 forwards the handover complete message to the E-UTRAN radio 152, which responds with an ACK (steps 618, 620). The WLAN radio 154 is then turned off (step 622) and the service is resumed via the E-UTRAN160 (step 614).

The procedure 600 is applicable to any form of handover between RANs. For example, the process 600 may be used for handover from I-WLAN to UTRAN.

Fig. 7 is a signaling diagram of an E-UTRAN initiated handover procedure 700, based on power class, from the I-WLAN170 to the E-UTRAN160, implemented in accordance with the present invention. The WTRU150 includes an E-UTRAN radio 152, and a WLAN radio 154. The WTRU150 is currently attached to the E-UTRAN160 and listens to E-UTRAN channels (e.g., BCCH) (step 702). The E-UTRAN160 sends (i.e., broadcasts, multicasts, or unicasts) a list of other RANs (e.g., I-WLAN, UTRAN, GERAN, or GAN) that are active within the coverage area of the E-UTRAN160 (step 704). The WTRU150 receives the list and stores the list (step 706). The WTRU150 then sends an additional information request, such as the location of the service area of the RAN (step 708). The E-UTRAN160 then retrieves the request message and sends it to the WTRU150 (step 710). The information may include information regarding service area location, radio technology used by the RAN, supported frequencies, and data rates, among other things.

The E-UTRAN radio 152 then forwards the I-WLAN information to the WLAN radio 152, which includes a list of frequencies to assist the WLAN radio in searching for a valid WLAN and activating the WLAN radio (steps 712, 714). The WLAN radio 154 monitors the WLAN channel according to the frequency list and measures the power level of the signal from the I-WLAN170 (step 716). The WLAN radio 154 then sends the measurement report to the E-UTRAN radio 152 (step 718), and the E-UTRAN radio 152 forwards the measurement report to the E-UTRAN160 (step 720).

The E-UTRAN160 selects a target I-WLAN based on the measurement report (step 722). The E-UTRAN160 sends a handover trigger message to the WTRU150 containing information about the target I-WLAN (step 724). The E-UTRAN radio 152 forwards the information to the WLAN radio 154 (step 726). The WLAN radio 154 then searches for the channel of the target WLAN based on the information and locks onto the target WLAN (step 728). The WLAN radio 154 sends a message to the I-WLAN170 to initiate the WLAN service (step 730).

When the I-WLAN170 receives the message, the I-WLAN170 initiates an authentication procedure and may assign a new IP address based on the interactive situation. Authentication messages are exchanged between the I-WLAN170 and the E-UTRAN160 (step 732). Once the WTRU is authenticated, the I-WLAN170 sends an access grant message to the WTRU150 (step 734). The WLAN radio 154 then sends a handover complete message to the E-UTRAN radio 152 (step 736). The E-UTRAN radio 152 then forwards the handover complete message to the E-UTRAN160 (step 738). Control messages for routing data via the I-WLAN170 are exchanged between the E-UTRAN160 and the I-WLAN170 (step 740). Once a new route is established, the E-UTRAN160 sends an ACK to the E-UTRAN radio 152 (step 742), and the E-UTRAN radio 152 forwards the ACK to the WLAN radio 154 (step 744). The service is then resumed via the I-WLAN170 (step 746).

The procedure 700 is applicable to any form of handover between RANs. For example, the process 700 may be used for handover from UTRAN to I-WLAN, in which case the UTRAN sends a list of valid RANs, each within the coverage area of the UTRAN, and the WTRU reports measurements to the UTRAN, and the UTRAN triggers handover from the UTRAN to the I-WLAN based on the measurements.

Examples

1. In a wireless communication system including a plurality of Radio Access Networks (RANs) configured according to different Radio Access Technologies (RATs) and a wireless transmit/receive unit (WTRU), a method for initiating a handover between the RANs.

2. The method of embodiment 1 comprising a first RAN sending a list to the WTRU, the list comprising RANs commonly located within a coverage area of the first RAN.

3. The method as in any embodiments 1 and 2 comprising the WTRU receiving a list from the first RAN and storing the list.

4. A method as in any of embodiments 1-3 comprising the WTRU determining whether one of the co-located RANs complies with a handover criterion and selecting one of the co-located RANs that complies with the handover criterion.

5. The method as in any embodiments 1-4 comprising the WTRU initiating a handover from the first RAN to the selected RAN.

6. The method as in any embodiments 1-5 further comprising the WTRU requesting information about service area locations of the co-located RANs from the first RAN, whereby the WTRU initiates a handover to the selected RAN if the service area location of the selected RAN is within a predetermined range.

7. The method of embodiment 6 wherein the WTRU continuously determines whether the service area location of the selected RAN is within the predetermined range as the WTRU moves.

8. The method as in any one of embodiments 1-7 further comprising the WTRU measuring a signal power level received from the co-located RAN and the first RAN, whereby the WTRU initiates the handover to the selected RAN if a signal power level received from the selected RAN exceeds the signal power level received from the first RAN.

9. The method as in any embodiments 1-8 further comprising the WTRU requesting additional information comprising at least one of: the serving location, radio technology, and frequency and data rate of the co-located RAN in the list, whereby the WTRU may trigger the handover based on the additional information.

10. A method as in any of embodiments 2-9 wherein a first RAN is an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) and the co-located RANs in the area are at least one of: a UMTS Terrestrial Radio Access Network (UTRAN), a GSM/EDGE radio Access network (GERAN), a Generic Access Network (GAN), and an IEEE-based Interactive Wireless local area network (I-WLAN).

11. A method as in any of embodiments 2-9 wherein the first RAN is an IEEE-based interactive wireless local area network (I-WLAN) and the co-located RAN is at least one of: an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), a UMTS Terrestrial Radio Access Network (UTRAN), a GSM/EDGE radio access network (GERAN), and a Generic Access Network (GAN).

12. A method as in any of embodiments 2-9 wherein the first RAN is a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN) and the co-located RAN is an IEEE-based interactive wireless local area network (I-WLAN).

13. A method as in any of embodiments 2-9 wherein the first RAN is an IEEE-based interactive wireless local area network (I-WLAN) and the co-located RAN is a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN).

14. A wireless communication system includes a plurality of Radio Access Networks (RANs) configured according to different Radio Access Technologies (RATs) and a WTRU.

15. The system of embodiment 14 wherein a first RAN is configured to send a list of RANs that are commonly located within a coverage area of the first RAN.

16. A system as in any of embodiments 14-15 wherein a wireless transmit/receive unit (WTRU) is configured to receive the list from the first RAN.

17. The system as in any of embodiments 14-16 wherein the wireless transmit/receive unit (WTRU) is configured to determine whether one of the co-located RANs complies with a handover criterion.

18. A system as in any of embodiments 14-17 wherein a wireless transmit/receive unit (WTRU) is configured to select one of the co-located RANs that meets the handover criteria.

19. The system as in any one of embodiments 14-18 wherein the wireless transmit/receive unit (WTRU) is configured to initiate a handover from the first RAN to the selected RAN.

20. The system as in any of embodiments 14-19 wherein the WTRU is configured to request information regarding service area locations of the co-located RANs from the first RAN, monitor the service area locations of the WTRU and the selected RAN, and initiate a handover to the selected RAN if the service area location of the selected RAN is within a predetermined range.

21. The system as in any of embodiments 14-20 wherein the WTRU is configured to measure a power level of signals received from the co-located RAN and the first RAN, whereby the WTRU initiates the handover to the selected RAN based on the measured power level.

22. A system as in any of embodiments 14-21 wherein the WTRU is configured to request additional information comprising at least one of: service area location, radio technology, and frequency and data rate at the co-located RAN, whereby the WTRU may trigger the handover based on the additional information.

23. A system as in any of embodiments 15-22 wherein the first RAN is an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) and the co-located RAN is at least one of: a UMTS Terrestrial Radio Access Network (UTRAN), a GSM/EDGE radio Access network (GERAN), a Generic Access Network (GAN), and an IEEE-based Interactive Wireless local area network (I-WLAN).

24. A system as in any of embodiments 15-22 wherein the first RAN is an IEEE-based interactive wireless local area network (I-WLAN) and the co-located RAN is at least one of: an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), a UMTS Terrestrial Radio Access Network (UTRAN), a GSM/EDGE radio access network (GERAN), and at least one Generic Access Network (GAN).

25. A system as in any of embodiments 15-22 wherein the first RAN is a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN) and the co-located RAN is an IEEE-based interactive wireless local area network (I-WLAN).

26. A system as in any of embodiments 15-22 wherein the first RAN is an IEEE-based interactive wireless local area network (I-WLAN) and the co-located RAN is a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN).

27. In a wireless communication system including a plurality of Radio Access Networks (RANs) configured according to different Radio Access Technologies (RATs) and at least one wireless transmit/receive unit (WTRU), a method for initiating a handover between the RANs.

28. The method of embodiment 27 comprising a first RAN sending a list to the WTRU, the list comprising RANs commonly located within a coverage area of the first RAN.

29. The method of embodiment 28 comprising the WTRU receiving a list from the first RAN and storing the list.

30. A method as in any of embodiments 28-29 comprising a WTRU measuring a quality of a signal received from a co-located RAN.

31. A method as in any of embodiments 28-30 comprising the WTRU sending a signal quality measurement report to the first RAN.

32. A method as in any of embodiments 28-31 comprising the first RAN determining whether the co-located RAN meets a handover criterion and selecting one of the co-located RANs that meets the handover criterion.

33. A method as in any of embodiments 28-32 comprising the first RAN initiating a handover from the first RAN to the selected RAN.

34. A method as in any of embodiments 27-33 comprising the WTRU requesting additional information from the first RAN comprising at least one of: serving location, radio technology, and frequency and data rate at the co-located RAN, whereby the WTRU may use the additional information to measure the signal quality.

35. A method as in any of embodiments 28-34 wherein the first RAN is an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) and the co-located RAN is at least one of: a UMTS Terrestrial Radio Access Network (UTRAN), a GSM/EDGE radio Access network (GERAN), a Generic Access Network (GAN), and an IEEE-based Interactive Wireless local area network (I-WLAN).

36. A method as in any of embodiments 28-34 wherein the first RAN is an IEEE-based interactive wireless local area network (I-WLAN) and the co-located RAN is at least one of: an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), a UMTS Terrestrial Radio Access Network (UTRAN), a GSM/EDGE radio access network (GERAN), and a Generic Access Network (GAN).

37. A method as in any of embodiments 28-34 wherein the first RAN is a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN) and the co-located RAN is an IEEE-based interactive wireless local area network (I-WLAN).

38. A method as in any of embodiments 28-34 wherein the first RAN is an IEEE-based interactive wireless local area network (I-WLAN) and the co-located RAN is a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN).

39. A wireless communication system includes a plurality of Radio Access Networks (RANs) configured according to different Radio Access Technologies (RATs) and a WTRU.

40. The system of embodiment 39 wherein a first RAN is configured to send a list of RANs that are co-located within a coverage area of the first RAN and initiate a handover if the selected RAN meets a handover criterion based on a measurement report received by the first RAN.

41. The system as in any one of embodiments 39-40 wherein the wireless transmit/receive unit (WTRU) is configured to measure signal quality received from the co-located RAN and send a signal quality measurement report to the first RAN.

42. The system as in any of embodiments 39-41, wherein the WTRU is configured to request additional information from the first RAN including at least one of: the serving location, radio technology, and frequency and data rate of the co-located RAN, whereby the WTRU may use the additional information to measure the signal quality.

43. A system as in any of embodiments 40-42 wherein the first RAN is an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) and the co-located RANs in the area are at least one of: a UMTS Terrestrial Radio Access Network (UTRAN), a GSM/EDGE radio Access network (GERAN), a Generic Access Network (GAN), and an IEEE-based Interactive Wireless local area network (I-WLAN).

44. A system as in any of embodiments 40-42 wherein the first RAN is an IEEE-based interactive wireless local area network (I-WLAN) and the co-located RAN is at least one of: an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), a UMTS Terrestrial Radio Access Network (UTRAN), a GSM/EDGE radio access network (GERAN), and a Generic Access Network (GAN).

45. A system as in any of embodiments 40-42 wherein the first RAN is a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN) and the co-located RAN is an IEEE-based interactive wireless local area network (I-WLAN).

46. A system as in any of embodiments 40-42 wherein the first RAN is an IEEE-based interactive wireless local area network (I-WLAN) and the co-located RAN is a Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (UTRAN).

47. In a wireless communication system including an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) and a wireless transmit/receive unit (WTRU), a method for initiating a handover from the E-UTRAN to another Radio Access Network (RAN).

48. The method of embodiment 47 comprising the E-UTRAN sending a list to the WTRU, the list comprising RANs commonly located within a coverage area of the E-UTRAN.

49. A method as in any of embodiments 47-48 comprising the WTRU receiving a list from the E-UTRAN and storing the list.

50. A method as in any of embodiments 47-49 comprising the WTRU determining whether one of the co-located RANs meets a handover criterion and selecting one of the co-located RANs that meets the handover criterion.

51. A method as in any of embodiments 47-50 comprising the WTRU initiating a handover from the E-UTRAN to the selected RAN.

52. A method as in any of embodiments 47-51 comprising the WTRU requesting information about service area locations of the co-located RANs from the E-UTRAN whereby the WTRU initiates a handover to the selected RAN if the service area location of the selected RAN is within a predetermined range.

53. A method as in any of embodiments 47-52 comprising the WTRU measuring received signal power levels from the co-located RAN and the E-UTRAN, whereby the WTRU initiates the handover to the selected RAN if a received signal power level from the selected RAN exceeds a received signal power level from the E-UTRAN.

54. The method as in any embodiments 47-53 comprising the WTRU requesting additional information comprising at least one of: serving location, radio technology, and frequency and data rate of co-located RANs in the list, whereby the WTRU may trigger the handover based on the additional information.

55. A wireless communication system includes an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) configured to send a list of Radio Access Networks (RANs) to the WTRUs, the RANs being co-located within a coverage area of the E-UTRAN, at least one co-located RAN configured according to different Radio Access Technologies (RATs) and a WTRU.

56. The system of embodiment 55 wherein the WTRU is configured to receive the list from the E-UTRAN.

57. The system as in any of embodiments 55-56 wherein the WTRU is configured to determine whether one of the co-located RANs complies with a handover criterion.

58. The system as in any of embodiments 55-57 wherein the WTRU is configured to select one of the co-located RANs that meets the handover criteria.

59. The system as in any of embodiments 55-58 wherein the WTRU is configured to initiate a handover from the E-UTRAN to the selected RAN.

60. The system as in any of embodiments 55-59, wherein the WTRU is configured to request information from the E-UTRAN regarding service area locations of the co-located RANs, monitor service area locations of the WTRU and the selected RAN, and initiate a handover to the selected RAN if the service area location of the selected RAN is within a predetermined range.

61. The system as in any of embodiments 55-60 wherein the WTRU is configured to measure a power level of signals received from the co-located RAN and the E-UTRAN, whereby the WTRU initiates the handover to the selected RAN based on the measured power level.

62. The system as in any embodiments 50-61, wherein the WTRU is configured to request additional information comprising at least one of: service area location, radio technology, and frequency and data rate at the co-located RAN, whereby the WTRU may trigger the handover based on the additional information.

63. In a wireless communication system including an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) and a wireless transmit/receive unit (WTRU), a method for initiating a handover from a second Radio Access Network (RAN) to the E-UTRAN.

64. The method of embodiment 63 comprising the second RAN sending a list to the WTRU, the list comprising E-UTRAN co-located within a coverage area of the E-UTRAN.

65. A method as in any of embodiments 63-64 comprising the WTRU receiving a list from the second RAN and storing the list.

66. A method as in any of embodiments 63-65 comprising a WTRU determining whether the E-UTRN meets a handover criterion.

67. A method as in any of embodiments 63-66 comprising the WTRU initiating a handover from the second RAN to the E-UTRAN if the handover criteria are met.

68. The method as in any embodiments 63-67 comprising the WTRU requesting additional information comprising at least one of: serving location, radio technology, and frequency and data rate of the E-UTRAN, whereby the WTRU may trigger the handover based on the additional information.

69. A wireless communication system includes an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), at least one other radio access network co-located within a coverage area of the E-UTRAN, and a WTRU.

70. The system of embodiment 69 wherein the another RAN is configured to send a list of active E-UTRAN within a coverage area of the another RAN.

71. The system as in any of embodiments 69-70 wherein the WTRU is configured to receive the list from the another RAN.

72. The system as in any of embodiments 69-71 wherein the WTRU is configured to determine whether the E-UTRN meets a handover criterion.

73. The system as in any of embodiments 69-72 wherein the WTRU is configured to initiate a handover from the another RAN to the E-UTRAN if the handover criteria is met.

74. The system as in any of embodiments 69-73 wherein the WTRU is configured to request additional information comprising at least one of: service area location, radio technology, and frequency and data rate of the E-UTRAN, whereby the WTRU may trigger the handover based on the additional information.

75. In a wireless communication system including an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), an interactive wireless local area network (I-WLAN), and a wireless transmit/receive unit (WTRU), a method for initiating a handover between the E-UTRAN and the I-WLAN.

76. The method of embodiment 75 comprising the WTRU monitoring I-WLAN channels while the WTRU is attached to the E-UTRAN.

77. The method as in any embodiments 75-76 comprising the WTRU locking onto a detected I-WLAN channel.

78. The method as in any one of embodiments 75-77 comprising the WTRU initiating a handover procedure if a criterion for handover to the I-WLAN is met.

79. A wireless communication system includes an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), an IEEE-based interactive wireless local area network (I-WLAN), and a wireless transmit/receive unit (WTRU).

80. The system of embodiment 79 wherein the WTRU comprises an E-UTRAN radio unit.

81. The system as in any of embodiments 79-80 wherein the WTRU includes an I-WLAN radio.

82. The system as in any embodiments 79-81 wherein the WTRU includes a handover controller.

83. The system of embodiment 82 wherein the handover controller is configured to monitor an I-WLAN channel while the WTRU is attached to the E-UTRAN.

84. The system as in any embodiments 82-83, wherein the handover controller is configured to lock onto a detected WLAN channel.

85. The system as in any of embodiments 82-83 wherein the handover controller is configured to initiate a handover procedure by the WTRU if a criterion for handover to the I-WLAN is met.

86. In a wireless communication system including an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), an interactive wireless local area network (I-WLAN), and a wireless transmit/receive unit (WTRU), a method for initiating a handover between the E-UTRAN and the I-WLAN.

87. The method of embodiment 86 comprising the WTRU monitoring E-UTRAN channels while the WTRU is attached to the I-WLAN.

88. A method as in any of embodiments 86-87 comprising the WTRU locking to a detected E-UTRAN channel.

89. A method as in any of embodiments 86-88 comprising the WTRU initiating a handover procedure if handover criteria from the I-WLAN to the E-UTRAN are met.

90. A wireless communication system includes an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), an IEEE-based interactive wireless local area network (I-WLAN), and a wireless transmit/receive unit (WTRU).

91. The system of embodiment 90 wherein the WTRU comprises an E-UTRAN radio unit.

92. The system as in any of embodiments 90-91 wherein the WTRU includes an I-WLAN radio.

93. The system as in any embodiments 90-92 wherein the WTRU comprises a handover controller.

94. The system of embodiment 93 wherein the handover controller is configured to monitor an E-UTRAN channel while the WTRU attaches to the I-WLAN.

95. The system as in any one of embodiments 93-94, wherein the handover controller is configured to lock onto a detected E-UTRAN channel.

96. The system as in any embodiments 93-95, wherein the handover controller is configured to initiate a handover procedure if a handover criterion to the E-UTRAN is met.

97. In a wireless communication system including a plurality of radio access networks and a wireless transmit/receive unit, the radio access networks are configured according to different radio access technologies, a method of initiating a handover between the radio access networks.

98. The method of embodiment 97 comprising transmitting an inter-access network message with a first radio access network to a wireless transmit/receive unit regarding locally available third generation partnership project and non-third generation partnership project access technologies.

99. A method as in any of embodiments 97-98 comprising receiving and storing the inter-access network information with the wtru.

100. A method as in any of embodiments 97-99 comprising initiating the handover with the wtru based on the inter-access network information.

101. A method as in any of embodiments 98-100 wherein the inter-access network information is provided at the time of the wtru request.

102. A method as in any of embodiments 98-101 wherein operator preferences are included in the inter-access network information based on locally available third generation partnership project and non-third generation partnership project access technologies.

103. A method as in any of embodiments 98-102 wherein the inter-access network information is limited to access technologies and networks that the wtru is capable of using based on at least one of the wtru capabilities or wtru subscription.

Although the features and elements of the present invention are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention. Although the present invention has been described in terms of preferred embodiments, other variations which do not depart from the scope of the invention as claimed will become apparent to those skilled in the art.

Claims (11)

1. A method for use in a wireless transmit/receive unit (WTRU), the method comprising:

transmitting a request message to an access network to request information about the access network;

receiving a response message from the access network in response to the request message, the response message including handover policy information related to access networks of two or more technology types;

initiating a handover to a target access network selected from the access networks in the response message based on the handover policy.

2. The method of claim 1, wherein the information related to the access networks comprises access technology types and communication parameters for each access network.

3. The method of claim 1, wherein transmitting the request message and receiving the response message are performed using an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) network.

4. The method of claim 1, wherein transmitting the request message and receiving the response message are performed using an ieee802.xx network.

5. The method of claim 1, wherein the target access network is an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) network.

6. The method of claim 1, wherein the target access network is an ieee802.xx network.

7. A method for use in a wireless transmit/receive unit (WTRU), the method comprising:

receiving a first message comprising a list of access networks of one or more technology types;

transmitting a request message to an access network to request information about the access network in response to the first message;

receiving a response message from the access network in response to the request message and including handover policy information;

and initiating the switching to the selected target access network based on the switching strategy information.

8. The method of claim 7, wherein transmitting the request message and receiving the response message are performed using an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) network.

9. The method of claim 7, wherein transmitting the request message and receiving the response message are performed using an ieee802.xx network.

10. The method of claim 7, wherein the target access network is an evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) network.

11. The method of claim 7, wherein the target access network is an IEEE802.xx network.