Method and apparatus for switching connection in wireless communication system

1. A method for switching, by a source cell, a connection in a wireless communication system, the method comprising:

receiving a first indication indicating that a target cell finishes expanding coverage or turning on power, from the target cell;

if the source cell receives the first indication, deciding radio resource control (RRC) connection switching to the target cell when the source cell is going to turn power off or shrink coverage, wherein the RRC connection switching is decided without a measurement report transmitted from a user equipment (UE);

if the source cell decides the RRC connection switching to the target cell, transmitting an aggregated UE context transfer message to the target cell and transmitting an RRC connection switching message to all UEs in coverage of the source cell, wherein the aggregated UE context transfer message and the RRC connection switching message are transmitted after the source cell knows that the target cell finishes expanding coverage or turning on power before the source cell starts turning power off or shrinking coverage; and

turning power off or shrinking coverage when the RRC connection switching to the target cell is finished,

wherein the RRC connection switching message includes information on an identity of the target cell, a second indication to inform the all UEs that the source cell is going to turn power off or shrink coverage and a period during which the UE should finish the RRC connection switching to the target cell,

wherein the period is determined by the source cell, and

wherein coverage of the source cell is included in coverage of the target cell which finishes expanding coverage or turning on power.

2. The method of claim 1 , further comprising:

receiving an aggregated UE context transfer acknowledge message which indicates successful reception of the aggregated UE context transfer message from the target cell.

3. The method of claim 1 , wherein the RRC connection switching message is transmitted via a broadcasting message or an RRC message.

4. The method of claim 1 , further comprising:

transmitting an aggregated sequence number (SN) status transfer message to the target cell.

5. The method of claim 1 , further comprising:

receiving a UE context release message from the target cell; and

releasing resource for the UE.

6. A method for switching, by a user equipment (UE), a connection in a wireless communication system, the method comprising:

if radio resource control (RRC) connection switching to a target cell is decided by a source cell without a measurement report transmitted from the UE, receiving a RCC connection switching message from the source cell which serves the UE after the source cell knows that the target cell finishes expanding coverage or turning on power before the source cell starts turning power off or shrinking coverage, wherein the RRC connection switching message includes information on an identity of the target cell, a second indication to inform all UEs that the source cell is going to turn power off or shrink coverage and a period during which the UE should finish RRC connection switching to the target cell,

performing synchronization to the target cell before the source cell starts turning power off or shrinking coverage;

receiving an RRC connection switching complete message from the target cell before the source cell starts turning power off or shrinking coverage; and

resuming communication with a network when the RRC connection switching to the target cell is finished,

wherein the period is determined by the source cell,

wherein coverage of the source cell is included in coverage of the target cell which finishes expanding coverage or turning on power,

wherein the source cell decides the RRC connection switching to the target cell when the source cell is going to turn power off or shrink coverage and receives a first indication from the target cell, and

wherein the first indication indicates that the target cell finishes expanding coverage or turning on power.

7. The method of claim 6 , wherein the RRC connection switching message is received via a broadcasting message or an RRC message.

8. The method of claim 6 , further comprising:

transmitting an RRC connection reconfiguration message to the target cell.

9. An eNodeB (eNB) controlling a source cell in a wireless communication system, the eNB comprising:

a radio frequency (RF) unit for transmitting or receiving a radio signal; and

a processor coupled to the RF unit, and configured to:

receive a first indication indicating that a target cell finishes expanding coverage or turning on power, from the target cell;

if the source cell receives the first indication, decide radio resource control (RRC) connection switching to the target cell when the source cell is going to turn power off or shrink coverage, wherein the RRC connection switching is decided without a measurement report transmitted from a user equipment (UE);

if the source cell decides RRC connection switching to the target cell, transmit an aggregated UE context transfer message to the target cell and transmit an RRC connection switching message to all UEs in coverage of the source cell, wherein the aggregated UE context transfer message and the RRC connection switching message are transmitted after the source cell knows that the target cell finishes expanding coverage or turning on power before the source cell starts turning power off or shrinking coverage; and

turn power off or shrink coverage when the RRC connection switching to the target cell is finished,

wherein the RRC connection switching message includes information on an identity of the target cell, a second indication to inform the all UEs that the source cell is going to turn power off or shrink coverage and a period during which the UE should finish the RRC connection switching to the target cell,

wherein the period is determined by the source cell, and

wherein coverage of the source cell is included in coverage of the target cell which finishes expanding coverage or turning on power.

10. The eNB of claim 9 , wherein the RRC connection switching message is transmitted via a broadcasting message or an RRC message.