KR100625447B1 - Power control device and method using maximum non-coupling method between layer cells - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a power control apparatus and method using a maximum non-coupling technique between layer cells.

2. The technical problem to be solved by the invention

The present invention eliminates backward interference of a mobile station by applying a hierarchical maximal ratio combining (HMRC) technique in a hierarchical cell environment, thereby reducing system performance without additional frequency allocation between inter-layer cell layers. To provide a power control apparatus and a method for improving the capacity and increasing the capacity, and a computer-readable recording medium recording a program for realizing the method.

3. Summary of Solution to Invention

The present invention relates to a wireless communication system having a hierarchical cell structure consisting of multiple microcells and multiple macrocells, wherein a base station corresponding to a microcell in which the mobile terminal is located in a state where the mobile terminal is located in an arbitrary microcell, The base station corresponding to each of the other microcells adjacent to the cell, the base station corresponding to the upper macrocell of the microcell in which the mobile terminal is located, and the base station corresponding to each of the other macrocells adjacent to the macrocell, respectively, the mobile station. Demodulation of the transmission signal of the terminal, the maximum ratio between the hierarchical cells applying a maximum ratio combination (MRC) to the carrier to interference ratio (CIR) of the mobile station transmission signal demodulated in each base station Mating; And a comparison unit configured to increase or decrease the power of the mobile terminal transmission signal based on a comparison between the maximum non-coupling result value applied by the hierarchical non-coupling unit between the hierarchical cells and a preset threshold.

4. Important uses of the invention

The present invention is used in a wireless communication system having a hierarchical cell structure.

Hierarchical Cell, Maximum Non-Combined (MRC), Maximum Non-Combined Between Layer (HMRC), Microcell, Macrocell

Description

Power control device and method using maximum non-coupling method between layer cells {APPARATUS AND METHOD FOR CONTROLING POWER USING HMRC IN MULTI-LAYER CELL ENVIRONMENT}             

1 is a block diagram of a conventional power control device.

2 is an explanatory diagram showing a hierarchical cell structure including multiple macrocells and microcells according to the present invention;

3 is a diagram illustrating an embodiment of a power control apparatus using a maximum non-coupling technique between hierarchical cells according to the present invention;

4 is a flowchart illustrating an embodiment of a power control method using a maximum non-coupling method between hierarchical cells according to the present invention;

* Explanation of symbols for the main parts of the drawings

31: terminal 32: wireless channel unit

33 ~ 3n: base station 34: maximum non-coupling unit (HMRC) between hierarchical cells

35: comparison unit 36: power control unit

The present invention provides a Code Division Multiple Access (CDMA) cellular mobile communication system, a Personal Communication System (PCS), a Trunk Radio System (TRS), and other mobile devices used in foreign countries. Maximum inter-layer cells in a hierarchical cell environment of a wireless communication system such as a communication system, a next generation mobile communication system such as the International Mobile Telecommunication-2000 (IMT-2000) and the Universal Mobile Telecommunication System (UMTS) currently being promoted in North America and Europe. Power control device and method that can improve system performance and increase capacity without additional frequency arrangement between inter-layers by eliminating backward interference of mobile terminal by applying HMRC technique, and A computer readable recording medium having recorded thereon a program for realizing the method.

1 is a block diagram of a conventional power control apparatus.

As shown in FIG. 1, the transmission signal of the mobile terminal 11 passes through the multi-path wireless channel unit 12 and then decodes through the demodulation unit 13 of the base station and the neighboring base station to which the mobile terminal 11 belongs. Spreading is demodulated.

Subsequently, the signals demodulated through each demodulator 13 are selected by the selective combiner 14 with a signal having a maximum value by comparing these signals at the base station controller. In this way, the signal-to-noise ratio (S / N) of the selected signal is compared with the threshold value through the comparison unit 15 and then transferred to the power control unit 16 to control the transmission power increase and decrease command. This process also applies to handover.

As such, power control is conventionally performed in non-layer cells in which cells do not overlap.

On the other hand, the CDMA hierarchical cell system is one of the ways to increase the capacity of the system, the macrocell covers a large area with a small amount of call, the microcell covers a small area that is constantly or temporarily busy in the macrocell It is a cell. Therefore, the microcell can be installed dynamically in an area where a hotspot occurs in the macrocell, and the microcell can accommodate the hotspot generated through the macrocell.

However, in the conventional power control method, the overall system performance and capacity are deteriorated unless the hotspot, which is a part of a call in a CDMA cellular system, is covered with a micro cell. In addition, when environmental changes occur in a macrocell covering a large area in the related art, there is a concern that the call may be continuously or temporarily concentrated in some areas.

Therefore, in such a case, it is necessary to introduce a microcell for accommodating such a call without changing the conventional macrocell, and to solve the signal interference problem and the capacity deterioration problem between the microcell and the macrocell that may occur at this time. A solution is required.

The present invention was devised to meet the above requirements, and by applying a Hierarchical Maximal Ratio Combining (HMRC) technique in a hierarchical cell environment to remove the backward interference of the mobile terminal, the hierarchical cell layer To provide a power control device capable of improving system performance and increasing capacity without additional frequency arrangement in the inter-layer, and a method thereof and a computer-readable recording medium recording a program for realizing the method. There is this.

The apparatus of the present invention for achieving the above object is a microcell in a hierarchical cell structure consisting of multiple microcells and multiple macrocells, in which a mobile terminal is located in an arbitrary microcell, where the mobile terminal is located. A base station corresponding to each of the other microcells adjacent to the microcell, a base station corresponding to the upper macrocell of the microcell in which the mobile terminal is located, and each of the other macrocells adjacent to the macrocell. A corresponding base station demodulates a transmission signal of the mobile terminal at each of the corresponding base stations, and a maximum ratio combining ratio (MRC) to a carrier to interference ratio (CIR) of the mobile terminal transmission signal demodulated at each base station. Maximum non-coupling unit between layer cells to apply); And a comparison unit configured to increase or decrease the power of the mobile terminal transmission signal based on a comparison between the maximum non-coupling result value applied by the maximum non-coupling unit between the hierarchical cells and a preset threshold.

On the other hand, the method of the present invention, in a method applied to a wireless communication network of a hierarchical cell structure consisting of multiple microcells and multiple macrocells, in a state where the mobile terminal is located in an arbitrary microcell, the mobile terminal is located in a microcell in which the mobile terminal is located. A corresponding base station, a base station corresponding to each of the other microcells adjacent to the microcell, a base station corresponding to the upper macrocell of the microcell in which the mobile terminal is located, and a corresponding base station corresponding to each of the other macrocells adjacent to the macrocell. Each base station demodulates a transmission signal of the mobile terminal, and when a demodulated mobile terminal transmission signal is received from each base station, a maximum ratio for a carrier to interference ratio (CIR) of each mobile terminal transmission signal is received. Applying Maximal Ratio Combining (MRC); And controlling to increase or decrease the power of the mobile terminal transmission signal based on a comparison between the applied maximum non-coupling result value and a preset threshold value.

On the other hand, the present invention, in the power control device connected to the wireless communication network, in a state where the mobile terminal is located in an arbitrary microcell, each base station corresponding to the microcell in which the mobile terminal is located, and each of the other microcells adjacent to the microcell Demodulating the transmission signal of the mobile terminal in each of the base station corresponding to the base station, the base station corresponding to the upper macro cell of the micro cell in which the mobile terminal is located, and the base station corresponding to each of the other macro cells adjacent to the macro cell, A function of applying a maximum ratio combining (MRC) to a carrier-to-interference ratio (CIR) of each mobile terminal transmission signal when the demodulated mobile terminal transmission signal is received from each base station; And a computer-readable recording medium having recorded thereon a program for realizing a function of increasing or decreasing the power of the transmission signal of the mobile terminal based on a comparison between the applied maximum non-binding result value and a preset threshold value. do.

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The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is an explanatory diagram showing a hierarchical cell structure including multiple macrocells and microcells according to the present invention.

As shown in FIG. 2, an area covered by one base station is defined as a cell, and a plurality of microcells exist in one macrocell, and each microcell has a structure adjacent to another microcell. Each macrocell also has a structure adjacent to other macrocells. Of course, the microcell configured outside the macrocell has a structure adjacent to other macrocells and microcells configured outside the other macrocell.

3 is a diagram illustrating an embodiment of a power control apparatus using a maximum non-coupling technique between hierarchical cells according to the present invention.

Referring to FIG. 2 for the purpose of understanding the present invention, in the hierarchical cell having the structure as shown in FIG. 2, in the present invention, when the mobile terminal is located in the microcell 1, the transmission signal of the mobile terminal is the microcell 1. A base station corresponding to microcell 2, microcell 3, and microcell 4 adjacent to this microcell 1, a base station corresponding to macrocell 1, which is an upper macrocell of this microcell 1, and this macro. Base station corresponding to each of the macro cell 2 and the macro cell 3 adjacent to the cell 1, demodulated in each, and thus the maximum ratio combining with respect to the carrier to interference ratio (CIR) of the mobile terminal transmission signal demodulated in each base station (MRC; Maximal Ratio Combining) is applied, and the power of the mobile terminal transmission signal is increased or decreased based on the comparison between the maximum ratio combining result and a preset threshold. Will perform control. For example, as mentioned above, the microcell in which the mobile terminal is located, the other microcells adjacent to the microcell, the upper macrocell of the microcell in which the mobile terminal is located, and the other macrocells adjacent to the macrocell, respectively, In the present invention, the maximum ratio combining (MRC) is applied to the carrier-to-carrier interference ratio (CIR) of the demodulated mobile station transmission signal in the present invention, which is defined as hierarchical maximal ratio combining (HMRC). Then, referring to Figure 3 will be described with respect to the device proposed in the present invention. As shown in FIG. 3, the transmission signal of the mobile terminal 31 passes through the multi-channel wireless channel unit 32 and then corresponds to a plurality of microcells in the vicinity of the cell where the mobile terminal 31 is located. The demodulators 331 to 3n1 and the demodulators 332 to 3n2 of each base station corresponding to the plurality of macrocells near the upper cell of the cell in which the mobile terminal 31 is located are de- demodulated.

The maximum non-coupling unit (34) between the hierarchical cells receiving the demodulated mobile terminal transmission signal by each base station applies the maximum non-coupling to the carrier-to-carrier interference ratio (CIR) of each mobile terminal transmission signal, and applies the maximum noncoupling result. The value is transferred to the comparator 35. Accordingly, the comparison unit 35 performs control to increase or decrease the power of the transmission signal of the mobile terminal based on a comparison between the maximum non-coupling result value received from the maximum non-coupling unit 34 between hierarchical cells and a preset threshold. . For example, the comparison unit 35 issues a power reduction command to the power control unit 36 when the maximum non-coupling result value is larger than the threshold value, and sends a power increase command to the power control unit when the maximum noncoupling result value is smaller than the threshold value. Get down to 36. Accordingly, the power control unit 36 performs power increase and decrease control on the transmission signal to the mobile terminal 31 according to the command of the comparator 35.

The aforementioned carrier-to-interference ratio (CIR) of the maximum uncombined mobile terminal transmission signal between hierarchical cells is determined by the difference between the microcell in which the mobile terminal is located, the other microcells adjacent to the microcell, and the microcell in which the mobile terminal is located. It is expressed as the sum of the macro cell and the other macro cells adjacent to the macro cell, and the carrier-to-interference wave ratio (CIR) of the mobile terminal transmission signal demodulated in each.

CIR _i = CIR _{macro1_i} + CIR _{macro2_i} +. + CIR _{macroN_i} + CIR _{micro1_i} + CIR _{micro2_i} +. + CIR _{microM_i}

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Where _i is the mobile terminal, CIR _i is the carrier-to-interference ratio of the maximum _uncombined mobile terminal transmission signal between hierarchical cells, CIR _{microM_i} is the _microcell where the mobile terminal is located, and each of the other microcells adjacent to the microcell. Carrier _bandwidth interference ratio of the demodulated mobile terminal transmission signal, CIR _{macroN_i} is the carrier _bandwidth interference of the demodulated mobile terminal transmission signal in the upper macro cell of the _microcell in which the mobile terminal is located and the other macro cells adjacent to the macro cell Represents a parbi.

When the maximum non-coupling between hierarchical cells is not used, the amount of mutual signal interference varies according to the proximity distance between the base station corresponding to the microcell and the base station corresponding to the macrocell in FIG. 2, and the system capacity and Although the performance is degraded, when the maximum non-coupling method between the hierarchical cells proposed in the present invention is used, a uniform CIR value can be obtained regardless of the installation position of the base station corresponding to the microcell.

In addition, in the hierarchical cell system, when the maximum non-coupling technique between layers is used, the system capacity is limited only to the total capacity (microcell capacity + macrocell capacity) and not limited to the capacity of individual cells. That is, even if the capacity in the microcell is exceeded, it can be accommodated in the macrocell. Therefore, using the maximum non-coupling technique between hierarchical cells, even if the microcell is placed anywhere in the existing macrocell, the reverse performance improvement and capacity increase effect can be obtained.

FIG. 4 is a flowchart illustrating a power control method using a maximum non-coupling technique between hierarchical cells according to the present invention, and will be described with reference to FIG. 2 for the purpose of understanding the present invention.

When the mobile terminal is located in the microcell 1, the base station corresponding to the microcell 1, the base station corresponding to each of the microcell 2, microcell 3 and microcell 4 adjacent to the microcell 1, and the A base station corresponding to the macro cell 1, which is an upper macro cell, and a base station corresponding to each of the macro cell 2 and the macro cell 3 adjacent to the macro cell 1, respectively, receive a signal from the mobile terminal through the reverse link (301). Accordingly, each of the base stations (microcell base stations 1 to m and macro cell base stations 1 to n) demodulates the mobile station transmission signals received by the base stations (302). The mobile station transmission signal demodulated by each base station is input to the maximum non-coupling unit 34 between hierarchical cells, and thus the maximum noncoupling unit 34 between hierarchical cells has a maximum ratio with respect to a carrier band interference ratio (CIR) of each mobile station transmission signal. After applying the combination, the applied maximum non-binding result is transmitted to the comparator 35 (303). Accordingly, the comparison unit 35 performs control to increase or decrease the power of the transmission signal of the mobile terminal based on a comparison between the maximum non-coupling result value received from the maximum non-coupling unit 34 between hierarchical cells and a preset threshold. 304. For reference, the result of applying the maximum ratio combining to the carrier-to-interference ratio (CIR) of each mobile terminal transmission signal is the signal-to-noise ratio (S / N) [Note; The interference wave usually means noise.

That is, the comparison unit 35 issues a power reduction command to the power control unit 36 when the maximum non-coupling result is greater than the threshold (305), and increases the power increase command when the maximum non-coupling result is smaller than the threshold. Lower to the power control unit 36 (306). Accordingly, the power control unit 36 performs power increase and decrease control on the transmission signal to the mobile terminal 31 according to the command of the comparator 35.

As a result, the reverse power control scheme using the maximum non-coupling between hierarchical cells controls the transmission power of each terminal to obtain a uniform CIR value for all terminals at the base station, and the capacity of the system can be maximized. In the CDMA cellular system, the system capacity of the reverse link can obtain the largest system capacity when the noise level of the terminals measured by the base station is the same. In the CDMA cellular system, the power control is to increase the system capacity by controlling the transmission power of the terminal as described above and making the reception level uniform for the terminals measured by the base station.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

According to the present invention as described above, if the reverse system capacity can be increased in the hierarchical cell structure, the power control can be easily performed without changing the system capacity even if the microcell is placed at an arbitrary position without frequency allocation work when the microcell is placed in the macrocell. There is an effect that can be performed.

Claims (6)

In a wireless communication system of a hierarchical cell structure consisting of multiple microcells and multiple macrocells, With the mobile terminal located in an arbitrary microcell, the base station corresponding to the microcell in which the mobile terminal is located, the base station corresponding to each of the other microcells adjacent to the microcell, and the parent of the microcell in which the mobile terminal is located Demodulating a transmission signal of the mobile terminal in each of a base station corresponding to a macro cell and a base station corresponding to each of the other macro cells adjacent to the macro cell, A maximum inter-cell maximum combining unit for applying a maximum ratio combining (MRC) to a carrier-to-interference ratio (CIR) of a mobile station transmission signal demodulated in each base station; And A comparator configured to increase or decrease the power of the transmission signal of the mobile terminal based on a comparison between a maximum non-coupling result value applied by the hierarchical non-coupling unit between the hierarchical cells and a preset threshold; Power control apparatus using a maximum non-coupling technique between layer cells comprising a. The method of claim 1, The comparison unit, If the maximum non-coupling result is greater than the threshold, control the power reduction command to be issued to the mobile terminal. If the maximum non-coupling result is less than the threshold, control to increase the power increase command to the mobile terminal. Power control device using a maximum non-coupling method between the layer cells. The method according to claim 1 or 2, The maximum uncombined result value includes a carrier bandwidth interference ratio of the maximum uncombined mobile terminal transmission signal between hierarchical cells, and the carrier bandwidth interference ratio of the maximum uncombined mobile terminal transmission signal between hierarchical cells is expressed by the following equation. Power control apparatus using the maximum non-coupling method between the layer cells, characterized in that represented. [Equation] CIR _i = CIR _{macro1_i} + CIR _{macro2_i} +. + CIR _{macroN_i} + CIR _{micro1_i} + CIR _{micro2_i} +. + CIR _{microM_i} Where _i is the mobile terminal, CIR _i is the carrier-to-interference ratio of the maximum _uncombined mobile terminal transmission signal between hierarchical cells, CIR _{microM_i} is the _microcell where the mobile terminal is located, and each of the other microcells adjacent to the microcell. Carrier _bandwidth interference ratio of the demodulated mobile terminal transmission signal, CIR _{macroN_i} is the carrier _bandwidth interference of the demodulated mobile terminal transmission signal in the upper macro cell of the _microcell in which the mobile terminal is located and the other macro cells adjacent to the macro cell Represents a favour. In the method applied to a wireless communication network of a hierarchical cell structure consisting of multiple microcells and multiple macrocells, With the mobile terminal located in an arbitrary microcell, the base station corresponding to the microcell in which the mobile terminal is located, the base station corresponding to each of the other microcells adjacent to the microcell, and the parent of the microcell in which the mobile terminal is located Demodulating a transmission signal of the mobile terminal in each of a base station corresponding to a macro cell and a base station corresponding to each of the other macro cells adjacent to the macro cell, Applying a maximum ratio combining (MRC) to a carrier-to-interference ratio (CIR) of each mobile terminal transmission signal when the demodulated mobile terminal transmission signal is received from each base station; And Performing control to increase or decrease the power of the mobile terminal transmission signal based on a comparison between the applied maximum non-coupling result value and a preset threshold value; Power control method using a maximum non-coupling method between layer cells including a. The method of claim 4, wherein In the performing of the mobile terminal transmission signal power increase and decrease control, If the maximum non-coupling result is greater than the threshold, control the power reduction command to be issued to the mobile terminal. If the maximum non-coupling result is less than the threshold, control to increase the power increase command to the mobile terminal. A power control method using a maximum non-coupling method between layer cells. In the power control device connected to the wireless communication network, With the mobile terminal located in an arbitrary microcell, the base station corresponding to the microcell in which the mobile terminal is located, the base station corresponding to each of the other microcells adjacent to the microcell, and the parent of the microcell in which the mobile terminal is located Demodulating a transmission signal of the mobile terminal in each of a base station corresponding to a macro cell and a base station corresponding to each of the other macro cells adjacent to the macro cell, A function of applying a maximum ratio combining (MRC) to a carrier-to-interference ratio (CIR) of each mobile terminal transmission signal when the demodulated mobile terminal transmission signal is received from each base station; And A function of increasing or decreasing the power of the mobile terminal transmission signal based on a comparison between the applied maximum non-coupling result value and a preset threshold value. A computer-readable recording medium having recorded thereon a program for realizing this.

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