Communications system, user equipment, mobility management entity and method thereof of transient handover for performing packet offloading

A method of a transient handover for performing packet offloading, used in a mobility management entity (MME) of a cellular network, the method comprising:

• finding at least one qualified user equipment (UE) from a plurality of user equipment (UEs) according to a determining method and transmitting a handover-transient request to the qualified UE;
• releasing a bearer resource of the qualified UE, retaining bearer information of the qualified UE, and handing over the qualified UE from a cellular network to a wireless local area network after receiving a handover-transient ACK transmitted from the qualified UE;
• receiving a first attachment request (ATTACH REQ) transmitted from the qualified UE after handing over the qualified UE from the cellular network to the wireless local area network;
• and
• transferring the qualified UE to an evolved packet system mobility management registered state (EMM-REGISTERED State) and re-establishing a cellular data path to handover the qualified UE from the wireless local area network to the cellular network,
• wherein the first ATTACH REQ is transmitted from the qualified UE when the qualified UE determines that the wireless local area network does not satisfy quality-of-service (Qos) of an application executed by the qualified UE, the first ATTACH REQ comprises a Request Type field, and the Request Type field indicates a handover procedure.

A method of a transient handover for performing packet offloading, used in a user equipment (UE) executing an application, wherein the UE attaches to a cellular network, the method comprising:

• receiving a handover-transient request from a mobility management entity (MME) in the cellular network;
• finding whether there is a wireless local area network;
• transmitting an access request to the wireless local area network when finding the wireless local area network;
• transmitting a handover-transient ACK to the MME when accessing the wireless local area network;
• handed over from the cellular network to the wireless local area network by the MME;
• detecting whether the wireless local area network satisfies quality-of-service (Qos) of the application after the UE is handed over from the cellular network to the wireless local area network;
• determining whether the wireless local area network satisfies the Qos of the application;
• transmitting a first attachment request (ATTACH REQ) to the MME when determining that the wireless local area network does not satisfy the Qos of the application;
• and
• entering an evolved packet system mobility management registered state (EMM-REGISTERED State), and is handed over from the wireless local area network to the cellular network,
• wherein the first ATTACH REQ comprises a Request Type field, and the Request Type field indicates a handover procedure.

A communications system of a transient handover for performing packet offloading, used in a cellular network, comprising:

• at least one qualified user equipment (UE), attaching to the cellular network and executing an application;
• and
• a mobility management entity (MME), coupled to the qualified UE, configured to find the qualified UE from UEs according to a determining method, and transmit a handover-transient request to the qualified UE,
• wherein the qualified UE finds and transmits an access request to a wireless local area network after receiving the handover-transient request;
• the qualified UE transmits a handover-transient ACK to the MME when accessing the wireless local area network;
• the MME releases a bearer resource of the qualified UE, retains bearer information of the qualified UE and hands over the qualified UE from the cellular network to the wireless local area network after receiving the handover-transient ACK;
• wherein the qualified UE detects whether the wireless local area network satisfies quality-of-service (Qos) of the application after the qualified UE is handed over from the cellular network to the wireless local area network;
• the qualified UE determines whether the wireless local area network satisfies the Qos of the application, and transmits a first attachment request (ATTACH REQ) to the MME when determining that the wireless local area network does not satisfy the Qos of the application;
• the MME receives the first ATTACH REQ transmitted from the qualified UE, transferring the qualified UE to an evolved packet system mobility management registered state (EMM-REGISTERED State), and re-establishes a cellular data path to handover the qualified UE from the wireless local area network to the cellular network,
• wherein the first ATTACH REQ comprises a Request Type field, and the Request Type field indicates a handover procedure.

A mobility management entity (MME), used in a cellular network, at least comprising:

• a control circuit;
• a processor installed in the control circuit;
• a memory installed in the control circuit and coupled to the processor;
• wherein the processor is configured to execute a program code stored in memory to execute a transient handover for performing packet offloading by:
• finding at least one qualified user equipment (UE) from a plurality of user equipment (UEs) according to a determining method and transmitting a handover-transient request to the qualified UE;
• and
• releasing a bearer resource of the qualified UE, retaining bearer information of the qualified UE, and handing over the qualified UE from the cellular network to a wireless local area network after receiving a handover-transient ACK transmitted from the qualified UE,
• wherein after handing over the qualified UE from the cellular network to the wireless local area network, the processor further executes:
• transferring the qualified UE to an evolved packet system mobility management registered state (EMM-REGISTERED State) when the MME receives a first attachment request (ATTACH REQ) transmitted from the qualified UE, and
• re-establishing a cellular data path to handover the qualified UE from the wireless local area network to the cellular network,
• wherein the first ATTACH REQ is transmitted from the qualified UE when the qualified UE determines that the wireless local area network does not satisfy quality-of-service (Qos) of an application executed by the qualified UE, the first ATTACH REQ comprises a Request Type field, and the Request Type field indicates a handover procedure.

A user equipment (UE), used to execute an application and attached to a cellular network, comprising:

• a control circuit;
• a processor installed in the control circuit;
• a memory installed in the control circuit and coupled to the processor;
• wherein the processor is configured to execute a program code stored in memory to execute a transient handover for performing packet offloading by:
• receiving a handover-transient request from a mobility management entity (MME) in the cellular network;
• finding whether there is a wireless local area network;
• transmitting an access request to the wireless local area network when finding the wireless local area network;
• transmitting a handover-transient ACK to the MME when accessing the wireless local area network;
• handing over from the cellular network to the wireless local area network by the MME;
• detecting whether the wireless local area network satisfies quality-of-service (Qos) of the application after the UE is handed over from the cellular network to the wireless local area network;
• determining whether the wireless local area network satisfies the Qos of the application;
• transmitting a first attachment request (ATTACH REQ) to the MME when determining that the wireless local area network does not satisfy the Qos of the application;
• and
• entering an evolved packet system mobility management registered state (EMM-REGISTERED State), and is handed over from the wireless local area network to the cellular network,
• wherein the first ATTACH REQ comprises a Request Type field, and the Request Type field indicates a handover procedure.