1. A method of providing location service for Wireless Local Area Network (WLAN) subscribers with a location subsystem preset in a WLAN and the WLAN subscribers having access to a 3rd Generation (3G) network via the WLAN location subsystem, the method comprising:
a) the WLAN location subsystem detecting whether a location request is received from a Location Service (LCS) client in the 3G network, if yes, going to b), otherwise repeating a);
b) the WLAN location subsystem locating a target User Equipment (UE) in the WLAN based on the received location request and returning a location result of the target UE in the WLAN to a Gateway Mobile Location Center (GMLC);
c) the GMLC forwarding the locating result to the LCS client;
wherein the WLAN location subsystem and the GMLC are connected with an Authentication, Authorization, Accounting (AAA) Server, respectively, the method further comprising before a):
a1) the LCS client sending the location request to the AAA Server;
a2) the AAA Server obtaining a subscription LCS information of the target UE, and detecting whether the target UE is permitted to be located based on the subscription LCS information; if yes, going to a3), otherwise returning to the LCS client the location result with error information, and ending;
a3) the AAA Server detecting whether the target UE is in an idle state, if not, sending the location request to the WLAN location subsystem and going to a), otherwise going to a4);
a4) the AAA Server further detecting whether there has been the location result corresponding to the target UE in the WLAN location subsystem, if yes, going to a5), otherwise sending the location request to the WLAN location subsystem and going to a);
a5) the AAA Server detecting whether the AAA Server is permitted to return the location result of the target UE in the WLAN location subsystem, if yes, returning the location result to the LCS client via the GMLC and then ending, otherwise returning to the LCS client the location result with error information, and ending; and,
further comprising in b) before the WLAN location subsystem locates the target UE based on the received location request, the WLAN location subsystem detecting whether there has been the location result of the target UE in the WLAN, if not, locating the target UE, storing the location result obtained, then returning the location result to the GMLC, otherwise obtaining the location result existing already in the WLAN location subsystem and returning the location result to the GMLC;
wherein the WLAN location subsystem returning the location result to the GMLC comprises the WLAN location subsystem sending via the AAA Server the location result corresponding to the target UE to the GMLC.', 'a) the WLAN location subsystem detecting whether a location request is received from a Location Service (LCS) client in the 3G network, if yes, going to b), otherwise repeating a);', 'b) the WLAN location subsystem locating a target User Equipment (UE) in the WLAN based on the received location request and returning a location result of the target UE in the WLAN to a Gateway Mobile Location Center (GMLC);', 'c) the GMLC forwarding the locating result to the LCS client;', 'wherein the WLAN location subsystem and the GMLC are connected with an Authentication, Authorization, Accounting (AAA) Server, respectively, the method further comprising before a):', 'a1) the LCS client sending the location request to the AAA Server;', 'a2) the AAA Server obtaining a subscription LCS information of the target UE, and detecting whether the target UE is permitted to be located based on the subscription LCS information; if yes, going to a3), otherwise returning to the LCS client the location result with error information, and ending;', 'a3) the AAA Server detecting whether the target UE is in an idle state, if not, sending the location request to the WLAN location subsystem and going to a), otherwise going to a4);', 'a4) the AAA Server further detecting whether there has been the location result corresponding to the target UE in the WLAN location subsystem, if yes, going to a5), otherwise sending the location request to the WLAN location subsystem and going to a);', 'a5) the AAA Server detecting whether the AAA Server is permitted to return the location result of the target UE in the WLAN location subsystem, if yes, returning the location result to the LCS client via the GMLC and then ending, otherwise returning to the LCS client the location result with error information, and ending; and,', 'further comprising in b) before the WLAN location subsystem locates the target UE based on the received location request, the WLAN location subsystem detecting whether there has been the location result of the target UE in the WLAN, if not, locating the target UE, storing the location result obtained, then returning the location result to the GMLC, otherwise obtaining the location result existing already in the WLAN location subsystem and returning the location result to the GMLC;', 'wherein the WLAN location subsystem returning the location result to the GMLC comprises the WLAN location subsystem sending via the AAA Server the location result corresponding to the target UE to the GMLC.

2. A method according to claim 1, wherein the AAA Server obtaining the subscribing location information in a2) comprises obtaining the subscription LCS information from a Home Location Register (HLR) or a Home Subscriber Server (HSS).

3. A method according to claim 1, wherein the WLAN subscribers are roaming ones; the GMLC in the 3G network comprises a Visiting Gateway Mobile Location Center (VGMLC) and a Home Gateway Mobile Location Center (HGMLC); and the AAA Server is connected with the VGMLC;
wherein the AAA Server sending the location result to the GMLC comprises sending the location result of the target UE to the HGMLC via the VGMLC; and
wherein the GMLC sending the location result to the LCS client comprises sending the location result of the target UE to the LCS client via the HGMLC.', 'wherein the AAA Server sending the location result to the GMLC comprises sending the location result of the target UE to the HGMLC via the VGMLC; and', 'wherein the GMLC sending the location result to the LCS client comprises sending the location result of the target UE to the LCS client via the HGMLC.

4. A method according to claim 1, wherein the LCS client is an external LCS client; the LCS client sending the location request to the AAA Server comprises the external LCS client sending the location request to the GMLC; and the GLMC, after receiving the location request, obtaining the routing information of the target UE and sending the location request to the corresponding AAA Server based on the routing information.

5. A method according to claim 1, wherein the LCS client is a 3G network; the LCS client sending the location request to the AAA Server comprises the 3G network sending the location request to the GMLC; and the GMLC, after receiving the location request from the 3G network, obtaining the routing information of the target UE and sending the location request to the corresponding AAA Server based on the routing information.

6. A method according to claim 4, wherein the GMLC obtaining the routing information of the target UE comprises obtaining the routing information of the target UE from a Home Location Register (HLR) or a Home Subscriber Server (HSS).

7. A method according to claim 1, wherein the LCS client is a WLAN subscriber; and the LCS client sending the location request to the AAA Server comprises the WLAN subscriber initiating the location request to the AAA Server via the WLAN.

8. A method according to claim 1, wherein the AAA Server in a5) detecting whether the AAA server is permitted to return the location result of the targeted UE in the WLAN location subsystem to the GMLC comprises the AAA Server detecting whether the AAA server is permitted to return the last location result of the target UE in the WLAN location subsystem to the GMLC according to the subscribing location information obtained in a2).

9. A method according to claim 1, wherein the interface between the GMLC and the AAA Server conforms to a Mobile Application Part (MAP) protocol.', '10. A method according to claim 1, further comprising before c): the GMLC sending a message of acknowledgement to an Authentication, Authorization, Accounting (AAA) Server.', '11. A method according to claim 1, wherein the WLAN location subsystem is connected with an Authentication, Authorization, Accounting (AAA) Server; and
in b), the WLAN location subsystem, before the locating operation, obtaining from the AAA Server a location parameter used for locating.', 'in b), the WLAN location subsystem, before the locating operation, obtaining from the AAA Server a location parameter used for locating.', '12. A method according to claim 5, wherein the GMLC obtaining the routing information of the target UE comprises of obtaining the routing information of the target UE from a Home Location Register (HLR) or a Home Subscriber Server (HSS).', '13. A system for providing location service for Wireless Local Area Network (WLAN) subscribers and the WLAN subscribers having access to a 3rd Generation (3G) network, the system comprising:
a WLAN location subsystem preset in a WLAN;
a Location Service (LCS) client is operable for initiating a location request in the 3G network;
a Gateway Mobile Location Center (GMLC), the GMLC is operable for forwarding a locating result to the LCS client; and
wherein the WLAN location subsystem is operable to detect whether the location request is received from the LCS client, the WLAN location subsystem locates a target User Equipment (UE) in the WLAN based on the received location request and returns the location result of the target UE in the WLAN to the GMLC;
an Authentication Authorization Accounting (AAA) Server connected with the WLAN location subsystem and the GMLC respectively;
wherein the AAA Server is operable for:
receiving the location request sent by the LCS client;
obtaining a subscription LCS information of the target UE and detecting whether the target UE is permitted to be located based on the subscription LCS information;
if the target UE is not permitted to be located, returning to the LCS client the location result with error information, and ending;
detecting whether the target UE being permitted to be located is in an idle state, otherwise sending the location request to the WLAN location subsystem if the target UE being permitted to be located is not in the idle state;
detecting whether there has been the location result corresponding to the target UE in the WLAN location subsystem if the target UE is in the idle state;
returning to the LCS client the location result with error information, and ending if there is no location result corresponding to the target UE;
detecting whether the AAA Server is permitted to return the location result of the target UE in the WLAN location subsystem if there has been the location result corresponding to the target UE;
returning the location result to the LCS client via the GMLC, and then ending if the AAA Server is permitted to return the location result of the target UE; and
returning to the LCS client the location result with error information, and ending if the AAA Server is not permitted to return the location result of the target UE;
wherein the WLAN location subsystem is further operable for detecting whether there has been the location result of the target UE in the WLAN, if not, locating the target UE, storing the location result obtained, then sending via the AAA Server the location result corresponding to the target UE to the GMLC; otherwise obtaining the location result existing already in the WLAN location subsystem and sending via the AAA Server the location result corresponding to the target UE to the GMLC.', 'a WLAN location subsystem preset in a WLAN;', 'a Location Service (LCS) client is operable for initiating a location request in the 3G network;', 'a Gateway Mobile Location Center (GMLC), the GMLC is operable for forwarding a locating result to the LCS client; and', 'wherein the WLAN location subsystem is operable to detect whether the location request is received from the LCS client, the WLAN location subsystem locates a target User Equipment (UE) in the WLAN based on the received location request and returns the location result of the target UE in the WLAN to the GMLC;', 'an Authentication Authorization Accounting (AAA) Server connected with the WLAN location subsystem and the GMLC respectively;', 'wherein the AAA Server is operable for:', 'receiving the location request sent by the LCS client;', 'obtaining a subscription LCS information of the target UE and detecting whether the target UE is permitted to be located based on the subscription LCS information;', 'if the target UE is not permitted to be located, returning to the LCS client the location result with error information, and ending;', 'detecting whether the target UE being permitted to be located is in an idle state, otherwise sending the location request to the WLAN location subsystem if the target UE being permitted to be located is not in the idle state;', 'detecting whether there has been the location result corresponding to the target UE in the WLAN location subsystem if the target UE is in the idle state;', 'returning to the LCS client the location result with error information, and ending if there is no location result corresponding to the target UE;', 'detecting whether the AAA Server is permitted to return the location result of the target UE in the WLAN location subsystem if there has been the location result corresponding to the target UE;', 'returning the location result to the LCS client via the GMLC, and then ending if the AAA Server is permitted to return the location result of the target UE; and', 'returning to the LCS client the location result with error information, and ending if the AAA Server is not permitted to return the location result of the target UE;', 'wherein the WLAN location subsystem is further operable for detecting whether there has been the location result of the target UE in the WLAN, if not, locating the target UE, storing the location result obtained, then sending via the AAA Server the location result corresponding to the target UE to the GMLC; otherwise obtaining the location result existing already in the WLAN location subsystem and sending via the AAA Server the location result corresponding to the target UE to the GMLC.', '14. A system according to claim 13, wherein the WLAN location subsystem is connected with an Authentication, Authorization, Accounting (AAA) Server and the WLAN location subsystem is further operable for obtaining from the AAA Server a location parameter used for locating.']