Pilot power setting method and femtocell using the same

A pilot power setting method and a femtocell using the same are disclosed. The pilot power setting method is for using in a femtocell which is operated in a closed mode to provide service to a user equipment (UE). The method includes the following steps. A communication link connecting the UE and the femtocell is established. A command is provided to the UE, which returns n items of path loss information to the femtocell in a pre-determined period according to the command, wherein n is a natural number which is greater than 1. A maximum path loss information between the UE and the femtocell is obtained from the n items of path loss information in the pre-determined period. A predicted pilot power is obtained according to the maximum path loss information. A pilot power of the femtocell is set according to the predicted pilot power.

This application claims the benefit of People's Republic of China application Ser. No. 201110242417.5, filed Aug. 23, 2011, the subject matter of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a pilot power setting method and a femtocell using the same, and more particularly to a pilot power setting method for using in a femtocell and a femtocell using the same.

2. Description of the Related Art

The femtocell technology has been developed to provide convenience to people in their everydayness. The femtocell is mostly used in a household or small office environment. The femtocell is linked to a system provider network via broadband for connecting the micro communication base station of the system provider network and the user equipment (UE) (such as a mobile phone) of the household or small office environment. In other words, through the disposition of the femtocell, the system provider network is extended to the household or small office environment.

Of the current technologies, the pilot power of the femtocell is mostly set by the network administrator by way of manual adjustment. As the femtocell becomes more and more popular, the current method will not be cost-wise in the future. Therefore, how to design a more efficient pilot power setting method has become a prominent task for the industries.

SUMMARY OF THE INVENTION

The invention is directed to a pilot power setting method and a femtocell using the same. A communication link between the femtocell and the user equipment (UE) is established. A command is provided to control the UE to return many items of path loss information to the femtocell in a pre-determined period. A maximum path loss information between the UE and the femtocell is obtained from the many items of path loss information in the pre-determined period. The pilot power setting method and the femtocell using the same of the invention further obtain a pilot power of the femtocell according to the maximum path loss information. As such, in comparison to the conventional femtocell, the pilot power setting method and the femtocell using the same the invention are advantageously capable of having the pilot power configured automatically.

According to a first aspect of the present invention, a pilot power setting method is disclosed. The pilot power setting method is for using in a femtocell which is operated in a closed mode to provide service to a user equipment (UE). The pilot power setting method includes the following steps. A communication link connecting the UE and the femtocell is established. A command is provided to the UE, which returns n items of path loss information to the femtocell in a pre-determined period according to the command, wherein n is a natural number which greater than 1. A maximum path loss information between the UE and the femtocell is obtained from the n items of path loss information in the pre-determined period. A predicted pilot power is obtained according to the maximum path loss information. A pilot power of the femtocell is set according to the predicted pilot power.

According to a second aspect of the present invention, a femtocell operated in a closed mode is disclosed for providing service to UE is provided. The femtocell includes a communication unit, a controlling unit, a path loss calculation unit and a pilot power setting unit. The communication unit is used for establishing a communication between the UE and the femtocell. The controlling unit is used for providing a command to the UE, which returns n items of path loss information to the femtocell in a pre-determined period according to the command, wherein n is a natural number which is greater than 1. The path loss calculation unit is used for obtaining a maximum path loss information between the UE and the femtocell from the n items of path loss information in the pre-determined period. The pilot power setting unit is used for obtaining a predicted pilot power according to the maximum path loss information and for setting a pilot power of the femtocell according to the predicted pilot power.

DETAILED DESCRIPTION OF THE INVENTION

The principles of the structure and operations of the invention are disclosed below with detailed descriptions and accompanying drawings.

Referring toFIG. 1, a block diagram of a femtocell according to an embodiment of the invention is shown. The femtocell1of the invention is operated in a closed mode for providing service to at least one user equipment (UE) having a special identification. In the present embodiment, the femtocell1provides service to one UE2.

The femtocell1includes a communication unit110, a controlling unit120, a path loss calculation unit130and a pilot power setting unit140. The controlling unit120and the path loss calculation unit130are coupled to the communication unit110, and the path loss calculation unit130is coupled to the pilot power setting unit140.

The communication unit110establishes a communication link C between the UE2and the femtocell1. The controlling unit120provides a command CMD to the UE2according to the command CMD, and returns n items of path loss messages PL_1, PL_2, . . . , PL_n to the femtocell1in a pre-determined period, wherein n is a natural number which is greater than 1.

For example, the command CMD is a radio resource control (RRC) command. The UE2continually detects the path loss between the UE2and the femtocell1in the pre-determined period according to the command CMD, and correspondingly returns n items of path loss information PL_1-PL_n.

The path loss calculation unit130obtains a maximum path loss information MAX_VIP_PATHLOSS (t0) between the UE2and the femtocell1according to the path loss information PL_1-PL_n in the pre-determined period. The maximum path loss information MAX_VIP_PATHLOSS (t0) is the maximum among the n items of path loss information PL_1-PL_n. Under the circumstances that the femtocell1provides service to many UE (such as j UE), the maximum path loss information MAX_VIP_PATHLOSS (t0) is the maximum of the items of path loss information (such as n×j items of path loss information PL1_1-PL1—n, PL2_1-PL2—n, . . . , PLj_1-PLj_n) returned by the UE in the pre-determined period.

The pilot power setting unit140obtains a predicted pilot power P_pilot (t0) according to the maximum path loss information MAX_VIP_PATHLOSS (t0) and accordingly sets a pilot power of the femtocell1. For example, the pilot power setting unit140determines the pilot power according to a received signal code power (RSCP) and a power offset of the UE. In other words, the pilot power setting unit140obtains the predicted pilot power P_pilot (t0) according to the following expression:
P_pilot(t0)=MAX_VIP_PATHLOSS(t0)+UE_acceptable_RSCP+Power_offset
Wherein, the UE_acceptable_RSCP and the power_offset respectively represent the RSCP and the power offset.

Thus, the femtocell1may set the pilot power according to the maximum path loss information MAX_VIP_PATHLOSS (t0) of the UE2in the pre-determined period.

For example, the femtocell1further includes a timing unit150coupled to the controlling unit120and the pilot power setting unit140. The timing unit150is switched on before the controlling unit120provides the command CMD, so as to record the time record TR, starting from the time point that the controlling unit120provides the command CMD.

After the pilot power setting unit140obtains the predicted pilot power P_pilot (t0), the timing unit150determines whether the time record TR is reached to a predetermined measuring time value. If the time record TR is not reached to the predetermined measuring time value, the timing unit150drives the controlling unit120, the path loss calculation unit130and the pilot power setting unit140to repeat their operations to correspondingly obtain another maximum path loss information MAX_VIP_PATHLOSS (t0+1) corresponding in the next pre-determined period and the corresponding predicted pilot power P_pilot (t0+1).

If the time record TR is reached to the predetermined measuring time value, it is indicated that the femtocell1has been performed for a time at least longer the predetermined set time value and many items of the pilot power are obtained. Accordingly, the femtocell1terminates its pilot power setting operation and sets the pilot power according to the lastly obtained predicted pilot power, such as the predicted pilot power P_pilot (t0).

Referring toFIG. 2, a flowchart of a pilot power setting method according to an embodiment of the invention is shown. The pilot power setting method of the present embodiment of the invention is for using in the femtocell1operated in a closed mode for providing service to at least one UE2. The pilot power setting method includes the following steps. Firstly, in step (a), the communication unit110establishes the communication link C between the UE2and the femtocell1.

Next, in step (b), the controlling unit120provides the command CMD to the UE2, which returns n items of path loss information PL_1-PL_n to the femtocell1in the pre-determined period according to the command CMD. Then, in step (c), the path loss calculation unit130obtains the maximum path loss information MAX_VIP_PATHLOSS between the UE2and the femtocell1from the n items of path loss information PL_1-PL_n in the pre-determined period.

Then, in step (d), the pilot power setting unit140obtains the predicted pilot power P_pilot (t0) according to the maximum path loss information MAX_VIP_PATHLOSS. Afterwards, in step (e), the pilot power setting unit140sets the pilot power of the femtocell1according to the predicted pilot power P_pilot (t0).

Referring toFIG. 3, another flowchart of a pilot power setting method according to an embodiment of the invention is shown. In other examples, the pilot power setting method further includes steps (f) and (g), respectively performed before step (b) and after step (d).

After step (a), the pilot power setting method proceeds to step (f), in which the timing unit150records the time record TR. After step (d), the pilot power setting method proceeds to step (g), in which the timing unit150determines whether the time record TR is reached to the predetermined measuring time value. If the time record TR is not reached to the predetermined measuring time value, then the pilot power setting method repeats steps (b) and (c) to obtain another maximum path loss information MAC_VIP_PATHLOSS (t0+1) and the predicted pilot power P_pilot (t0+1) in the next pre-determined period.

Following step (g), if the time record TR is reached to the predetermined measuring time value, it is indicated that the pilot power setting operation of the femtocell1has been performed for a time longer than the predetermined set time value and many items of the pilot power are obtained. In step (e), the femtocell1terminates its pilot power setting operation, and the pilot power setting unit140sets the pilot power of the femtocell1according to the lastly obtained predicted pilot power, such as the predicted pilot power P_pilot (t0).

A pilot power setting method and a femtocell are proposed in the present embodiment of the invention. A communication link between the femtocell and the user equipment (UE) is established. A command is provided to control the UE to return many items of path loss information to the femtocell in a pre-determined period. A maximum path loss information between the UE and the femtocell is obtained from the many items of path loss information in the pre-determined period. The pilot power setting method and the femtocell of the invention further obtain a pilot power of the femtocell according to the maximum path loss information. As such, in comparison to the conventional femtocell, the pilot power setting method and the femtocell according to the present embodiment of the invention are advantageously capable of having the pilot power configured automatically.