Handover between a cellular system and a wireless local area network

Handover between cellular system and wireless local area network

Creative field

This creation is about wireless digital communication. In particular, this creation is about the interaction and connection transfer (handoff) between the cellular network and the regional wireless network where the geographic location of the device can be determined.

background

Mobile wireless communication has progressed from a closed platform in cell phones based mainly on voice to a variety of open platforms that support data and voice, such as smart phones, laptops, and personal digital assistants (PDAs). Different types of wireless services include WLAN and cellular networks. When a user wants to switch between different services in an unfamiliar geographic area, it is difficult to determine the available services. Generally, users must contact the wireless service provider to determine which services are available in a specific geographic area. If a user travels in many different geographic areas, the burden of trying to determine which effective service is available in that geographic area becomes too great.

Therefore, it is relatively simple for the user presence to determine the demand for services in a specific geographic area.

Comprehensive description

A core network in a wireless communication system is used for the handover of a wireless transmission and reception unit (WTRU) between a cellular network and a wireless local area network (WLAN). The WLAN communicates with a cellular network and the location of the WTRU is determined. The area coverage area of the WLAN is determined. When the WTRU approaches the coverage area of WLAN (13), the WTRU is notified of the existence of WLAN (13). When the WTRU is located within the coverage area of the WLAN (13), the WTRU is handed over from the cellular network to the WLAN (13), and vice versa.

Detailed description of the preferred embodiment

This creation will be described in detail with reference to the accompanying drawings, in which the same reference numerals always represent the same elements. This creation is about a wireless communication system with user equipment whose geographic location can be determined. In particular, this creation is a system for handover between a cellular system and a wireless local area network (WLAN) based on his/her location, and vice versa. The user equipment can be, for example, a wireless PDA with a WLAN card. Thereafter, any such user equipment will be marked as a wireless transmission and reception unit (WTRU). The location of the WTRU can be determined by one of several establishment methods. For example, the WTRU may use the built-in GPS receiver to determine its own location. The second method is to use a network based on a regional approach. In the network based on the area method, the network uses AOA (ang1e of arriva1, angle of arrival) or TDOA (time difference of The arrival; arrival time difference) technology or other technologies determine the location of a WTRU, whereby the calculation of the WTRU's location is performed by the network at the base station, point B or anywhere in the fixed part of the network. In the case of a WLAN, this WLAN can provide these calculations. In a cellular mobile phone or a wireless PDA or a WLAN card or a combination of these, in the time distance of the TDOA location, the WTRU establishes communication with the network, and the network determines the location by knowing the transmission and reception time. The WTRU's signal is received at different antenna positions. Because each antenna is at a different distance from the caller (usually), the signal arrives at a slightly different time. The base station receiver related to the antenna position is synchronized by the atomic clock and adjusted for the latency of the internal signal. The base station receiver sends the caller's call and time data to open to mobile handover, where the time is compared and calculated to generate the caller's latitude and longitude. This technology requires signal time information from at least three different antenna locations, but does not require WTRUS to have internal location equipment. The third method can be a hybrid GPS/network location method, where the network assists the WTRU to determine its own location more efficiently than having a built-in independent GPS receiver. This is advantageous because of the limited availability of GPS signals.

In any case, it follows many methods that can be used to determine the location of the WTRU.

Each method will produce an assessment of the location of the relevant difference with the assessment error. The location of this WTRU is known to the network at all times.

The network that provides cell and WLAN coverage also has the geographic location of the coverage area. The geographic location of the coverage area can be calculated by the network by knowing the coverage area of the cellular network or WLAN and knowing the geographic location of the cell or WLAN transmitter. This method allows the network to determine the geographic location of the covered area. The WTRU is a dual-mode device capable of simultaneously accessing cellular networks and WLANs. The WTRU periodically sends the updated location to the core network.

If a user with a WTRU with access to cellular networks and wireless LANs moves through a cellular network and arrives in an area without cell coverage but with WLAN coverage, or the same user is moving through a cell coverage area that also has WLAN access The point of the network, which can be notified of the existence of the WLAN coverage area through the push service. This push service can be any application-level trigger, such as being called (paged), the use of SMS. This will enable the user to decide whether he/she wants to switch to WLAN. This switching decision can be based on many factors, such as the cost of the WLAN, the speed and data processing capacity of the WLAN compared with the cellular network, and the requirements of the currently used applications.

The same technique can be applied when a user with a WTRU with access to the cellular network and wireless LAN is located in the WLAN and has the option of switching to the cellular network.

Figure 1 shows the general structure of a wireless communication system, which includes a cellular network 10, a core network 11, a mobile unit, such as a wireless transmission and reception unit (WTRU) 12, and a WLAN 13. In many cases, the cellular network 10 will be an integral part of the core network 11, and the WLAN 13 will sometimes also be an integral part of the core network 11. The WTRU 12 communicates with the core network 11 via a radio frequency access network (RAN) 10 for transmission to the WLAN 13. The core network 10 can be any network connected to a cellular radio frequency access network (RAN) (such as GSM RAN, IS-95RAN, CDMA RAN or WCDMA RAN) (similar to IS-41 core network, GPRD IP core network, or expanded GSM core network). The WTRU 12 can communicate with a cellular radio frequency access network (RAN) 10 or a different local area network, such as WLAN 13.

The core network 11 includes a WLAN service location database 23 and a location comparison device 24. The location device 26 allows the core network 11 to determine the location of the WTRUS 12.

According to this creation, the WTRU 12 has the ability to support connection transfer between the cellular network 10 and the WLAN 13. The WTRU 12 includes a cellular network device 32, a WLAN communication device 33, and a connection transfer device 34. Alternatively, WTRUs 12 may have a GPRS receiver 35.

The location determination can be performed by the cell 10 or the core network 11, using location information that already exists in the network, or by the WTRU 12, for example, using a GPS receiver 35. The location of WTRU 12 may be determined by using signals from WTRU 12. This signal can be established from one of the GPS receivers, using AOA (angle of arrival), TDOA (time differenCe of arrival), hybrid GPS/network location method, or any other convenient method. In addition, a cell service location database 27 is provided, which includes the coverage area location information of the cell service instead of the WLAN 13 coverage area. The WLAN service area database 23 and the cellular service location database 27 are matched with the location information by the location comparison device 24. The use of the database enables the information in the databases 23, 27 to be used when the mobile connection can be transferred from WLAM to the cellular network. This allows information related to the usability of the cellular network to be pushed through the WLAN 13.

If the WTRU 12 determines the location, the location is sent to the core network 11, for example by sending information signals. The WLAN service location database 23 includes information related to the geographic location of the WLANS, such as the WLAN 13. The WLAN 13 communicates with the core network 11 and can update/modify the content of the WLAN service location database. The WTRU 12 includes a cellular netbook communication device 32, a WLAN communication device 33, and a connection transfer device 34 for assisting the connection transfer between the core network 11 and the WLAN 13. The location comparison device 24 uses the WLAN service location database 23 to find the WLANs serving the WTRUs 12 at the determined location.

In operation, the core network 11 communicates with the WTRU 12 via the cellular radio frequency access network (RAN) 10, such as the base station 25. As part of the communication function, the core network 11 can provide connection transfer information. This includes the availability of WLAN 13 based on the location of WTRUS.

In the configuration, the WTRU 12 provides location data from the GPS receiver 35 to the core network 11. This location data indicates the location of the WTRU 12. This information is provided to the location comparison device 24, which compares the location of the WTRU 12 with the service area of a known local wireless network, such as WLAM 13, and the base station 25 of the core network 11 and the WLAN service location database 23 provided with these The mapping data related to the radio frequency coverage area of the local wireless network.

Further information, such as price, speed, service existence, and available coverage area of WLANS are also provided to WTRU 12. Effectively, this information is provided by push communication to the user, such as by the push service device 36 as indicated. "Push communication" means to describe the requirements of information, called "push" service, and does not have the information that users specifically request at that time. To illustrate, the network 11 identifies a WLAN 13 in the vicinity of a WTRUs. The network 11 sends the price and speed information of the WLAN 13 to the WTRU 12. The user of the WTRU 12 can decide whether to use the WLAN 13, or can be selected "on the fly" during the school-based notification of the WLAN service. When deciding whether to accept a connection transfer in advance, the user can edit the program of the connection transfer information in advance.

Similarly, there may be certain types of users wishing to end the communication or end the communication when leaving the coverage area of the WLAN. An example is the use of free or low-cost services, such as high-bandwidth data transmission, or the provision of regional voice communication services. Therefore, it is better for the WLAN 13 to notify the WTRU when the WLAN service will lose connection or there is a connection transfer to one of the core networks 11. Preferably, the user can refuse to continue the service after the connection is transferred to the core network 11, and it is better that the user can decide whether to accept the connection transfer before the connection transfer.

The core network 11 may additionally provide information to the WLAN 13 to assist in handover, for example, information indicating that the WTRU I2 may be able to receive signals from the WLAN 13. After the handover, WLAN 13 can also provide a "push broadcast" service.

These services can be provided continuously. Such information may include shopping information, or information related to directions in the WLAN 13. Mobile users can choose to receive this information. To illustrate, the user can enable a WLAN feature, and the WTRU 12 can receive WLAN information without requiring it. The provision of the WLAN service location database 23 and the cell service location database 27 provide information on the effectiveness of connection transfer between the WLAN and the cell service. This database information may also be provided to the WTRU 12 through a "push broadcast" sent to the WTRU via a WLAN or cellular network.

WTRU 12 may provide information to WLAN 13 when WTRU 12 is served by WLAN 12. When any WTRU 12 provides location information to the WLAN 13, or when the WLAN 13 determines the location of the WTRU 12, the location information of the WTRU 12 is updated by the WLAM 13 in the core network 11. This information is used by the location comparison device 24 in the core network 11 for connection transfer from the WLAN to the cellular network, if necessary.

Referring to FIG. 2, the WTRU 12 passes through the cellular network 10. The location of this WTRUs is tracked. The WLAN boundary 62 is provided by the known plaintext ciphertext pair (priori) of the network 11 or by the WLAN 13. Therefore, the core network 11 knows the current or approximate location of the WTRU 12 and the coverage area of the WLAN 13. As can be seen, the information from the WTRU 12 is provided to the core network 11, where the WTRU 12 periodically updates the core network 11 with respect to the location of the WTRU 12. It can also be seen that the WLAN 13 provides information to the core network 11. This information may include information such as the coverage area of the WLAN 13 and the services provided by the WLAN 13. The core network 11 provides information about the existence of the WLAN 13 network to the WTRU 12. The information from the core network to the WTRU 12 can be a "push broadcast" guest news.

When the WTRU 12 moves through the geographic area served by the WLAN 13, the cellular network 10 serving the WTRU 12 notifies the WTRU 12 of the existence of the WLAN 13, for example, by using the cellular network 10's "push" service. The user can then choose to switch networks, switching from cellular network 10 to WLAN 13.

In another step as shown in Figure 3, switching between networks can be performed automatically. In Figure 3, the cellular RAN 10 no longer exists in the geographic area that WTRU1 2 faces.

As can be seen, information from the WTRU 12 is provided to the core network 11, where the WTRU 12 periodically updates the core network 11 with respect to the location of the WTRU 12.

At the same time, it can also be seen that the WLAN 13 provides information to the core network 11. This information can include the coverage area of the WLAN 13 and the guest information of the services provided by the WLAN 13, as well as provide information about the existence of the WLAN 13 network to the WTRU. 12. Your news from the core network to WTRU 12 can be "push broadcast" information.

As shown in FIG. 2, the cell RAN10 has a coverage area 61. The WLAN 13 has a coverage area 62, part of which is outside the core network coverage area 61. If the core network 11 determines that the location of the WTRU 12 is within the WLAN coverage area 62, the core network 11 can notify the WTRU 12 of the availability of the WLAN service. When the WTRU 12 leaves the geographic coverage area 61 of the core network 11, the WTRU 12 is provided with information identifying the WLAN 13 related to the WLAN area 61 to the WTRU 12.

In this step, the handover to the WLAN 13 can be performed without the knowledge of the mobile user. Alternatively, mobile users can be advertised through the "push broadcast" service to determine whether the current wireless service is dropped or supported by the WLAN 13, which may be at an additional cost. If the WTRU is GPS-enabled or provided with location information, the WTRU may directly decide whether to initiate the handover.

The advantage of using the "push broadcast" service is that at the application level, the user can choose to switch the network and the cost and speed information related to the new service can be provided as part of the information that is pushed to the user. These costs can vary and depend on the number of users in the service providers network or other criteria. This "push broadcast" service allows users to have the latest information at all times.

<p>Figure 1 shows the general structure of a wireless communication system, one of which is a wireless mobile unit</p><p>To communicate with a core network in order to transfer the connection with the WLAN.</p><p>Figure 2 illustrates that the mobile terminal is served by a cellular network and has the option of using WLAN</p><p>Selected steps.</p><p>Figure 3 shows that the cellular network no longer exists and the mobile terminal is served by WLAN</p><p>Regional steps.</p>