WO2009075462A1

WO2009075462A1 - Method of automatic reception gain control in mobile station and apparatus for the same

Info

Publication number: WO2009075462A1
Application number: PCT/KR2008/005458
Authority: WO
Inventors: Tae Joong Kim; Gi Yoon Park; Soo Yun Hwang; Hyeong Jun Park
Original assignee: Electronics And Telecommunications Research Institute; Samsung Electronics.Co., Ltd.
Priority date: 2007-12-10
Filing date: 2008-09-16
Publication date: 2009-06-18
Also published as: KR20090060841A; WO2009075462A8; KR100943765B1

Abstract

The present invention relates to a method of automatic reception gain control in a mobile station, and an apparatus thereof. According to an exemplary embodiment of the present invention, in controlling the reception gain in the mobile station, a method of automatic reception gain control in an asynchronous mode is used when the mobile station does not ensure the synchronization with respect to a base station, and a method of automatic reception gain control in a synchronous mode is used when the mobile station ensures the synchronization with respect to the base station. Accordingly, the method of automatic gain control can be applied in combination. In addition, according to an exemplary embodiment of the present invention, when the method of automatic gain control in the synchronous mode is used in the mobile station, it can reduce the degree of gain variation that is changed in the automatic gain control by using a signal that is always transmitted from the base station at a designated time. Accordingly, the reception gain can be efficiently controlled.

Description

METHOD OF AUTOMATIC RECEPTION GAIN CONTROL IN MOBILE STATION AND APPARATUS FOR THE SAME

Technical Field

[1] The present invention relates to a method of automatic reception gain control in a mobile station, and an apparatus for the same.

[2] The present invention was supported by the IT R&D program of MIC/IITA

[2005-S-404-13, Research & Development of Radio Transmission Technology for 3G evolution].

Background Art

[3] Needs for a service that supports data in a form of packets has been increasing since the third generation mobile communication system. In particular, since packet- switched data has characteristics that a data rate transmission rate is very high and its variation is very large than that of circuit- switched data, needs for a method of efficiently transmitting the packet-switched data have increased.

[4] In order to meet these requests, as an example, in the 3GPP (3rd Generation Project

Partnership) among various communication environments, a standard in which a downlink packet service is offered through the HSDPA (High-Speed Downlink Packet Service) is provided. In addition, as another example, in the TIA/EIA (Telecommunication Industry Association/Electronic Industries Alliance), a standard in which a downlink packet service is offered through IxEV-DO or the like is provided. Since the packet service uses code and time as resources allocated to the packet, a signal variation is very large on a time domain compared to an allocation rule in circuit- switched service.

[5] Furthermore, in 3GPP, OFDM (Orthogonal Frequency Division Multiplexing) is used in the downlink as a signal of the physical layer for the LTE (Long-Term Evolution) standard. In the OFDM mode, a frequency band is divided into multiple bands, each band having a different gain and noise effect, and a proper number of data bits to be transmitted are allocated to each band. That is, in the OFDM mode, a sequence of continuous data in time is divided by a unit of predetermined time, and thereafter is converted in parallel. The data rate transmission rate can be increased in the OFDM mode such that each data converted in parallel is carried on a one or a plurality of allocated bands.

[6] Furthermore, discontinuity of transmission in time can be ensured since the continuous data is transmitted in parallel. Accordingly, scheduling can be efficiently performed in the packet-switched manner in which the variation of data transmission rate is very large. However, since a signal variation on the time domain is increased as much due to the discontinuity of transmission, there is a problem in that it is difficult to use the aforementioned mode in a method of automatic reception gain control in a mobile station.

[7] Therefore, a plan that enables a received signal-to-noise ratio (SNR) in the mobile station to be ensured as high as possible has been requested in order to control a receive gain in the mobile station when the signal variation on the time domain becomes larger.

[8] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Disclosure of Invention Technical Problem

[9] The present invention relates to a method of automatic receive gain control in a mobile station, and an apparatus for the same. More particularly, in controlling the receive gain in the mobile station, the present invention provides a system and a method in which a different method of automatic gain control can be applied according to the status of synchronization in a mobile station. Technical Solution

[10] In order to achieve the technical object of the present invention, the method of automatic receive gain control in the mobile station according to an exemplary embodiment of the present invention includes:

[11] judging whether the mobile station is in the in-sync status or the out-of-sync status; receiving a digital signal and a synchronization signal synchronized to a base station with respect to the digital signal and selecting a digital signal of a duration that is used to calculate a power from the digital signal when the mobile station is in the in-sync status as a result of the judging; calculating the power of the selected digital signal of the duration and calculating an amount of power variation through a difference between a reference power and the calculated power; and determining a reception gain based on the calculated amount of power variation and outputting a control signal for controlling the reception gain.

[12] In order to achieve the technical object of the present invention, the apparatus for automatic reception gain control in the mobile station according to another exemplary embodiment of the present invention includes: an analog processing section that receives a radio frequency signal, a feedback signal for gain control, and a feedback signal for low noise amplification control, converts the input signal to a digital signal, and outputs the digital signal; a synchronization signal generating section that receives the digital signal output from the analog processing section and outputs a synchronization signal by ensuring time synchronization; and a reception gain controlling section that receives the digital signal and the synchronization signal, selects a signal to be used in power calculation from the digital signal to calculate a reception power, and outputs the feedback signal for gain control and the feedback signal for low noise amplification control to the analog processing section using the calculated reception power.

Advantageous Effects

[13] Since signals used to calculate a power are separately selected in accordance with the in-sync status or the out-of-sync status in the mobile station, it can be possible to reduce the amount of power variation in calculation and enhance the performance of the signal-to-noise ratio. [14] In addition, the clipping effect generated in analog to digital conversion can be reduced and the automatic gain control in the mobile station can be efficiently performed.

Brief Description of the Drawings [15] FIG. 1 is a structural diagram of a general apparatus for automatic reception gain control in a mobile station. [16] FIG. 2 and FIG. 3 are illustrative views showing a time characteristic of a transmitted signal in accordance with a general transmission method. [17] FIG. 4 and FIG. 5 are illustrative views showing a general variation in signal on an axis of time. [18] FIG. 6 is a structural diagram of a general apparatus for automatic reception gain control in a mobile station according to an exemplary embodiment of the present invention. [19] FIG. 7 is an illustrative view showing a variation in signal on an axis of time according to an exemplary embodiment of the present invention. [20] FIG. 8 is a view illustrating status transfer in a method of automatic reception gain control in a mobile station according to an exemplary embodiment of the present invention. [21] FIG. 9 is a flowchart illustrating a method of automatic reception gain control in a mobile station according to an exemplary embodiment of the present invention.

Mode for the Invention [22] In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

[23] Throughout specification, unless explicitly described to the contrary, the word

"comprise" and variations such as "comprises" or "comprising" will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, the terms "-er", "-or" and "module" described in the specification mean units for processing at least one function and operation and can be implemented by hardware components or software components and combinations thereof.

[24] In this specification, a mobile station (MS) may designate a terminal, a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), user equipment (UE), an access terminal (AT), and so on. Moreover, the mobile station may include all or a part of functions of the mobile terminal, the subscriber station, the portable subscriber station, the user equipment, and so on.

[25] In this specification, a base station (BS) may designate an access point (AP), a radio access station (RAS), a node B, a base transceiver station (BTS), a mobile multihop relay (MMR)-BS, and so on. Further, the base station may include all or a part of functions of the access point, the radio access station, the node B, the base transceiver station, the MMR-BS, and so on.

[26] Before an exemplary embodiment of the present invention is described, a general apparatus for automatic reception gain control in a mobile station and a transmission method using the same are described with reference to FIG. 1 to FIG. 3.

[27] FIG. 1 is a structure diagram of a general apparatus for automatic reception gain control in a mobile station

[28] With reference to FIG. 1, a general apparatus for automatic reception gain control in a mobile station may include an antenna 10, an analog processing section 20, and a reception gain controlling section 30. The antenna 10 receives an RF signal. The analog processing section 20 receives the RF signal that is output through the antenna, processes the received RF signal, converts the received RF signal to a form of a digital signal, and outputs the digital signal. The reception gain controlling section 30 receives the digital signal from the analog processing section 20, calculates a power, and outputs feedback signals for gain control and low noise amplification (hereinafter referred to as "LNA") control to the analog processing section 20.

[29] The analog processing section 20 may include a low noise amplifier 21, a gain amplifier 22, and an analog-digital converter 23. The low noise amplifier 21 receives the RF signal, which is output from the antenna 10, and reflects a low noise amplification gain thereon. The gain amplifier 22 receives the signal, which is amplified with low noise, and reflects a reception gain thereon. The analog-digital converter 23 receives the signal that is amplified in gain, converts the signal into a form of digital signal, and transmits the digital signal to the reception gain controlling section 30.

[30] The reception gain controlling section 30 may include a power calculator 31, a power difference calculator 32, and a power accumulator 33. The power calculator 31 receives the digital signal that is processed at the analog processing section 20 and calculates an average power of the digital signal. The power difference calculator 32 calculates the difference between the average power calculated at the power calculator 31 and the reference power to calculate an amount of power variation. The power accumulator 33 adds the amount of power variation that is calculated at the power difference calculator 32 to the power that was already calculated, and calculates an accumulation power to be newly reflected.

[31] In addition, the reception gain controlling section 30 may include a power limiter 34, a low noise amplification filter 35, and a power controller 36. The power limiter 34 limits the newly calculated accumulation power to a maximum threshold value when the accumulation power exceeds the maximum threshold value for the reception gain control, limits the newly calculated accumulation power to a minimum threshold value when the accumulation power is less than the minimum threshold value, and outputs a power level signal as it is when the signal is in an operation range. The low noise amplification filter 35 filters the limited power level signal output from the power limiter 34 and outputs a control signal for controlling the low noise amplification. The power controller 36 receives the limited power level signal output from the power limiter 34 and the output signal of the low noise amplification filter, which is output from the low noise amplification filter 35, and generates a feedback signal for gain control and a feedback signal for low noise amplification control that are necessary to perform the gain control at the analog processing section 20.

[32] A time characteristic of a transmitted signal for when a gain of a received signal is controlled through the above apparatus will be described with reference to FIG. 2 and FIG. 3.

[33] FIG. 2 and FIG. 3 are illustrative views showing a time characteristic of a transmitted signal in accordance with a general transmission method. FIG. 2 is an illustrative view showing a time characteristic of transmitted signal in accordance with a continuous transmission method, and FIG 3 is an illustrative view showing a time characteristic of transmitted signal in accordance with an intermittent transmission method.

[34] The signal characteristic shown in FIG. 2 relates to a case where a signal power with respect to a continuously transmitted signal is always maintained, or a case where an amount of variation of the received signal is not large since a continuous resource allocation is achieved in downlink. Accordingly, the amount of power variation in the received signal, which is calculated at the power calculator 31, is not large, and thereby the amount of variation with respect to the reference power is also small.

[35] Therefore, even in a case where a signal-to-noise ratio has been increased by setting the reference power sufficiently high, a clipping phenomenon of the received signal due to an abrupt power increase can be prevented. That is, the reference power can be increased to make the signal-to-noise ratio high when the reception power is stable.

[36] The signal characteristic shown in FIG. 3 relates to a case where a continuously transmitted signal does not exist, or an amount of variation of the received signal is large since a discontinuous resource allocation is achieved in downlink. Accordingly, the amount of power variation in the received signal, which is calculated at the power calculator 31, becomes larger, and thereby the amount of variation with respect to the reference power becomes also larger.

[37] Therefore, the lower level of the power calculated at a specific time makes the higher level of the receive gain. However, in this case, the clipping phenomenon of the received signal may occur when the power of the received signals abruptly increases. This phenomenon can also occur by a time delay of operation that reflects the gain of the received signal in accordance with the variation of power.

[38] Therefore, in a case of the received signal shown in FIG. 3, the reference power

(compared with the level of calculate power) should be set very low in order to reduce the clipping phenomenon. This causes the signal-to-noise ratio to be lowered. As a result, the reference power should be set in accordance with the amount of calculated power variation of the received signal. When the method of using the above apparatus for automatic reception gain control is applied to a case where the amount of power variation is large, the reference power should be lowered.

[39] As described above, when a packet-switched signal that the amount of power of the signal is varied abruptly is used or when resources are allocated in order to effectively use time resources as in OFDM, the signal-to-noise ratio is reduced so that the number of bits in digital output from the analog-digital converter 23 in the analog processing section 20 should be increased. Also, the number of bits of a receiver that processes the digital signal is excessively increased. This is described with respect to FIG. 4 and FIG. 5.

[40] FIG. 4 and FIG. 5 are illustrative views showing a general variation in signal on an axis of time.

[41] As shown in FIG. 4, one time slot (T_n._! - T_n) represents a period of a transmitted signal. At an indicated time, there is always a signal transmitted from the base station. Thus, a predetermined power is maintained in this duration even at a time when packets are not actually allocated.

[42] First, a power is increased in a duration of T₃ - T₄ The increased power is maintained until the time of T₅ The power is decreased again in a duration of T₅ - T₆. Thereafter, the power is increased in a duration of T₆ - T₇ again. The reception gain is not reflected on this signal. This signal may represent a power level of a signal to be input to the analog processing section 20 in the mobile station.

[43] The power level of the signal shown in FIG. 4 is changed into the power level shown in FIG. 5 when the reception gain is reflected on the signal shown in FIG. 4 through the apparatus for automatic reception gain control in the mobile station. Here, a first line represents a level where the clipping occurs at the analog-digital converter 23. The signal exceeding the level can influence the performance since the clipping occurs at the analog-digital converter 23.

[44] A second line is a reception gain level. It is represented that a high level adds a large gain to the analog input signal and a low level adds a small gain to the analog input signal. In this case, the signal of the reception gain level is not abruptly reflected at the boundary of a time slot like the calculated amount of power, but is slowly changed at the boundary of a time slot. This is because the reception gain signal output from the analog processing section 20 is reflected in a condition having a predetermined time delay due to a characteristic of analog elements. A third line represents an amount of power calculated in a time slot. A fourth line represents a reference power level.

[45] With reference to FIG. 5, a general operation in the apparatus for automatic reception gain control in the mobile station is described. An average power during a time slot is calculated in the power calculator 31. Here, the amount of power is calculated relatively less compared to the signal level in a duration where the signal to be used exists. The difference between the amount of power calculated in this manner and the reference power level set currently is calculated at the power difference calculator 32. The difference is added to the power accumulator 33, thereby changing the current reception gain level.

[46] That is, when a signal that is greater than the reference power is received at the power difference calculator 32, a "negative" power difference is generated. The signal is added to the current reception gain level, thereby lowering the reception gain level. Accordingly, the apparatus operates toward lowering the reception gain level when a signal having a high power level is input.

[47] The reception gain level is not changed in durations of T₀ - T₁, T₁ - T₂, and T₂ - T₃ since the amount of power calculated at these durations is equal to the reference power. However, the amount of power calculated in the duration of T₃ - T₄ is abruptly increased, and the difference between the increased power and the reference power is calculated to reflect on the current reception gain. Therefore, the apparatus operates toward decreasing the reception gain (T₄ - T₅, the second line). Accordingly, the signal input to the analog processing section 20 in the duration of T₄ - T₅ shown in FIG. 4 is decreased like the signal power level in the duration of T₄ - T₅ shown in FIG. 5. That is, a small reception gain is reflected.

[48] Here, since the input signal power level is abruptly increased in the duration of T₃ - T

4, the clipping occurs when the instantaneous signal power level exceeds the clipping level. In order to prevent the clipping phenomenon, the clipping level should be increased. Meanwhile, in order to increase the clipping level, an additional bit should be allocated to the analog-digital converter 23. Therefore, the system complexity is increased. Accordingly, it is an important factor to decrease the clipping phenomenon in designing the apparatus for automatic reception gain control in the mobile station.

[49] The input signal in the duration of T₅ - T₆ has the same power as the signals in the durations of T₀ - T₃ have. However, since the reception gain in the mobile station has already been decreased, the signal output from the analog-digital converter 23 in the duration of T₅ - T₆ is input to the power calculator 31 in the condition of being lower than the signal in the duration of T₀ - T₃. In this case, the clipping phenomenon does not occur. However, since the difference between the clipping level and the signal level is increased, the analog-digital conversion is implemented in the condition that sufficient bits are not used in the conversion, and thereby the degradation of performance is generated in the characteristic of signal-to-noise ratio. Accordingly, when the operation of the apparatus for automatic reception gain control in the mobile station is designed, it is included in important factors to reduce the difference between the clipping level and the power level of the received signal in order to realize the characteristic of the signal-to-noise ratio as sufficiently as possible.

[50] The reception gain is increased in the duration of T₆ - T₇ due to the low power level measured in the duration of T₅ - T₆. However, the signal having a high level is actually input in the duration of T₆ - T₇, so that the clipping phenomenon occurs in the duration of T₆ - T₇ again. This clipping phenomenon can be prevented by further lowering the reference power. However, if the reference level is lowered, the performance of the signal-to-noise ratio is degraded, and thereby additional bits are required. Eventually, the structure of the receiver becomes complicated.

[51] According to a general operation of an apparatus for automatic reception gain control in a mobile station, if an input signal level is abruptly changed, a clipping phenomenon occurs or a phenomenon in which a signal level is extremely decreased in comparison to a clipping level occurs. Therefore, it is required that an apparatus for automatic reception gain control in a mobile station can reduce the possibility of the clipping and ensure the signal-to-noise ratio. This is described in detail with reference to FIG. 6.

[52] FIG. 6 is a structure diagram of a general apparatus for automatic reception gain control in a mobile station according to an exemplary embodiment of the present invention.

[53] As shown in FIG. 6, the apparatus for automatic reception gain control according to an exemplary embodiment of the present invention may include an analog processing section 100, a synchronization signal generating section 300, and a reception gain controlling section 200.

[54] The analog processing section 100 may include a low noise amplifier 130, a gain amplifier 110, and an analog-digital converter 120. Although constituent elements required to perform the function of a filter, a mixer, a frequency controller, or the like are included in the analog processing section 100 in addition to the low noise amplifier 130, the gain amplifier 110, and the analog-digital converter 120, constituent elements in association with only the apparatus for automatic reception gain control in the mobile station are described in the exemplary embodiment of the present invention.

[55] First, the low noise amplifier 130 reflects a low noise amplification gain on an RF signal input through an antenna. In this case, the low noise amplifier 130 receives a feedback signal for the low noise amplification control generated from a power controller 226 that is described below, and reflects the low noise amplification gain on the RF signal.

[56] The gain amplifier 110 receives the RF signal on which the low noise amplification gain is reflected at the low noise amplifier 130, and reflects a reception gain thereon. The gain amplifier 110 receives a feedback signal for gain control generated from the power controller 226 in order to reflect the reception gain.

[57] The analog-digital converter 120 receives the analog signal in which the gain is amplified at the gain amplifier 110, converts the analog signal to a digital signal, and transmits the digital signal to the reception gain controlling section 220.

[58] The reception gain controlling section 200 may include a signal selector 210 and a reception gain generator 220. The reception gain generator 220 may include a power calculator 221, a power difference calculator 222, a power accumulator 223, a power limiter 224, a low noise amplification filter 225, and a power controller 226.

[59] The signal selector 210 receives the synchronization signal generated from the synchronization signal generating section 300 and the digital signal output from the analog processing section 100, and selects a signal to be used to calculate a power of a digital signal.

[60] The synchronization signal generating section 300 receives the digital signal output from the analog processing section 100, and ensures time synchronization with the base station to output the synchronization signal. That is, the synchronization signal generating section 300 performs the functions of actually generating the synchronization signal and transmitting the ensured synchronization signal to the reception gain controlling section 200. In addition, the synchronization signal generating section 300 performs a function of setting the gain controller 200 to a synchronous mode.

[61] The synchronization is lost at the synchronization signal generating section 300 while the apparatus for automatic reception gain control is operated in the synchronous mode using the ensured synchronization signal. At this time, the synchronization signal generating section 300 judges that the synchronization signal generated by the synchronization signal generating section is unreliable. Then, the synchronization signal generating section 300 sets the reception gain controlling section 200 such that the mode of the reception gain controlling section 200 is changed to an asynchronous mode and the reception gain controlling section 200 is operated in the asynchronous mode.

[62] The power calculator 221 receives the digital signal that is selected at the signal selector 210 and calculates an average power of the digital signal. The power difference calculator 222 calculates the difference between the power calculated at the power calculator 221 and the reference power in order to calculate an amount of power variation. The power accumulator 223 adds the amount of power variation that is calculated at the power difference calculator 222 to the power that was already calculated, and calculates an accumulation power to be newly reflected on the signal gain control input to the analog processing section 100.

[63] The power limiter 224 compares the accumulation power calculated at the power accumulator 223 with a maximum threshold value or a minimum threshold value, and thereby a power is output in a limited state. That is, when the accumulation power calculated at the power accumulator 223 exceeds the maximum threshold value, the calculated accumulation power is limited to the maximum threshold value before the power level signal is output. In addition, when the accumulation power calculated at the power accumulator 223 is less than the minimum threshold value, the calculated power is limited to the minimum threshold value before outputting the power level signal. When the calculated accumulation power is in a range of operation, the calculated accumulation power is output as it is.

[64] The low noise amplification filter 225 filters the power level signal output from the power limiter 224 and outputs a control signal for controlling the low noise amplification. The power controller 226 receives the power level signal output from the power limiter 224 and the output signal of the low noise amplification filter output from the low noise amplification filter 225, and generates signals that are necessary to perform the gain control at the analog processing section 100. The signals generated at the power controller 226 are divided into a feedback signal for gain control that is input to the gain amplifier 110 and a feedback signal for low noise amplification control that is input to the low noise amplifier 130.

[65] With reference to FIG. 7, a characteristic of a received signal on which a gain control is reflected in the apparatus for automatic reception gain control having the above constituent elements is described. [66] FIG. 7 is an illustrative view showing a variation in signal on an axis of time according to an exemplary embodiment of the present invention.

[67] As shown in FIG. 7, by increasing the reference power and by not increasing the clipping level, the difference between the clipping level and the reference power can be decreased while the clipping phenomenon is decreased to some extent. Accordingly, the signal-to-noise ratio can be increased.

[68] Here, a first line represents a level where the clipping occurs at the analog-digital converter 120. The signal exceeding the level can influence the performance since the clipping occurs at the analog-digital converter 120.

[69] A second line is a reception gain level. It is represented that a high level adds a large gain to the analog input signal and a low level adds a small gain to the analog input signal. In this case, the signal of the reception gain level is not abruptly reflected at the boundary of time slot like the calculated amount of power, but is slowly changed at the boundary of time slot. This is because the reception gain signal output from the analog processing section 100 is reflected in a condition having a predetermined time delay due to a characteristic of analog elements.

[70] A third line represents an amount of power calculated in a time slot. A fourth line represents a reference power level. A fifth line represents an increased clipping level.

[71] When the signal-to-noise ratio is set as in FIG. 5 by increasing the clipping level like the fifth line, the clipping phenomenon dose not occur, and thereby a performance gain can be ensured. This is described in more detail. A power is calculated only at a time corresponding to a location indicated by a circle in FIG. 4.

[72] At the time corresponding to the location, there always exists a signal transmitted from the base station. In code division multiplexing access (CDMA), a whole time corresponds to this. In Mobile Wimax (also referred to as Wibro), a time of sending a preamble is repeated every 5ms. In 3GPP LTE, an OFDM symbol duration where a downlink reference signal is located corresponds to this. Also, in other systems, a mobile station grasps a power in a duration where a signal is set to be transmitted from a base station all the time.

[73] In order to set the aforementioned duration, the signal selector 210 receives the synchronization signal output from the synchronization signal generating section 300 and the digital signal output from the analog processing section 100, selects only the signal corresponding to the duration where a signal is set to be transmitted from a base station all the time, and transmits the selected signal to the power calculator 221. The power calculator 221 calculates an average power during a time slot only with respect to the signal selected by the signal selector 210. Since the signal to be used is selected in a condition that the mobile station has already recognized that the base station transmits the signal, the power is not calculated in the duration where the signal does not exist. Accordingly, the average power is increased to a predetermined level.

[74] The amount of power calculated in this manner is input to the power difference calculator 222. The power difference calculator 222 calculates the difference between the amount of power and the predetermined reference power level. The difference is added to the power accumulator 223, thereby changing the current reception gain level. That is, when a signal that is greater than the reference power is received at the power difference calculator 222, a "negative" power difference is generated. The signal is added to the current reception gain level, thereby lowering the reception gain level. Accordingly, the apparatus operates toward lowering the reception gain level when a signal having a high power level is input.

[75] The reception gain level is not changed in durations of T₀ -T₃ shown in FIG. 7 since the amount of power calculated at these durations is equal to the reference power. However, since the amount of power calculated in the duration of T₃ - T₄ is abruptly increased, the difference between the increased power and the reference power is calculated by the power difference calculator 222 to reflect the current reception gain (T₄ - T₅, the second line). However, since the average power has already been increased to a predetermined level, the amount of power variation is less than that in FIG. 5.

[76] Accordingly, the signal input to the analog processing section 100 during the duration of T₄ - T₅ shown in FIG. 4 is decreased like the signal power level in the duration of T₄ - T₅ shown in FIG. 7. That is, a small reception gain is reflected. Although the signal is abruptly decreased in FIG. 5 the signal is not abruptly decreased in this case. Since the amount of power variation is decreased, only a small variation is represented.

[77] Here, since the input signal power level is abruptly increased in the duration of T₃ - T

4, the clipping occurs when the instantaneous signal power level exceeds the clipping level. Since the reference power is increased in order to increase the signal-to-noise ratio, the phenomenon occurs. When the clipping level is increased in a condition of maintaining the signal-to-noise ratio as in FIG. 7 (the fifth line), the clipping does not occur. Since the apparatus for automatic reception gain control in the mobile station according to an exemplary embodiment of the present invention ensures a small amount of power variation, the clipping phenomenon is overcome, and thereby it is possible to obtain an effect of increasing the signal-to-noise ratio.

[78] The input signal in the duration of T₅ - T₆ has the same power that the signals in the durations of T₀ - T₃ have. However, since the reception gain in the mobile station has already been decreased, the signal output from the analog-digital converter 120 in the duration of T₅ - T₆ is input to the power calculator 221 in the condition of being lower than the signal in the duration of T₀ - T₃. [79] Here, unlike in FIG. 5 where the received signal is set to be excessively small due to the abrupt variation in the amount of power in comparison to the clipping level, only a small decrease in the signal is reflected. Thus, it is prevented that the received signal is excessively decreased in comparison to the clipping level (the value indicated as "G2" in FIG. 7). Accordingly, a sufficiently high signal-to-noise ratio can be ensured.

[80] In addition, since the power level measured in the duration of T₅ - T₆ is low, the reception gain is increased during the period of T₆ - T₇. However, since the amount of variation is small, the clipping phenomenon does not occur. The digital signal can be stably output at the analog processing section 100.

[81] The aforementioned method of automatic reception gain control is a method in accordance with a synchronous mode. However, in a condition in which the mobile station is initialized or the mobile station loses the synchronization signal, it is difficult to perform the method of automatic reception gain control through the synchronous mode. Therefore, a synchronous mode and an asynchronous mode should be able to be used selectively. This will be described with reference to FIG. 8.

[82] FIG. 8 is a view illustrating a status transfer in a method of automatic reception gain control in a mobile station according to an exemplary embodiment of the present invention.

[83] As shown in FIG. 8, the initialized status in the mobile station is in the asynchronous mode. Accordingly, the power is calculated using the method of automatic reception gain control in accordance with the asynchronous mode. Here, the method of automatic reception gain control in accordance with the asynchronous mode is used since the synchronization signal is not acquired in the method of automatic reception gain control in the mobile station according to the above embodiment of the present invention. In the asynchronous mode, the synchronization signal generated from the synchronization signal generating section 300 is ignored and an arbitrary signal among signals input from the analog processing section 100 is selected to calculate a power.

[84] However, when the mobile station acquires the synchronization with respect to the corresponding base station, the status of the mobile station is transferred to the in-sync status, so that the method of automatic reception gain control in accordance with the synchronous mode is used. In the method of automatic reception gain control according to the synchronous mode, the signal used to calculate the power is selected using the method described with reference to FIG. 6 and FIG. 7.

[85] That is, when the mobile station is initialized, the automatic gain control is performed under the asynchronous mode and the asynchronous mode is maintained until the synchronization is acquired through the synchronization acquisition process. The synchronization signal generating section 300 ensures the synchronization with respect to the base station to generate the synchronization signal and orders the reception gain controlling section 200 to be set to the synchronous mode together with the generated synchronization signal. Then, the apparatus for automatic reception gain control transfers to the in-sync status and operates in the synchronous mode.

[86] In a case of acquiring the synchronization, the mobile station performs the automatic reception gain control in accordance with the synchronous mode. When losing the synchronization, the mobile station transfers to the out-of-sync status. In this case, the mobile station again performs the process for synchronization acquisition. Here, when the synchronization signal generating section 300 judges the synchronization signal generated from the synchronization signal generating section 300 to be unreliable due to the loss of synchronization, the synchronization signal generating section 300 is set such that the reception gain controlling section 200 can be changed to the asynchronous mode and be operated in the asynchronous mode. Since this operation is already known to the public, the detailed description is omitted in the exemplary embodiment of the present invention.

[87] The aforementioned method of performing the automatic reception gain control in the mobile station by selectively using the in-sync status and out-of-sync status is described with reference to FIG. 9.

[88] FIG. 9 is a flowchart illustrating a method of automatic reception gain control in a mobile station according to an exemplary embodiment of the present invention.

[89] As shown in FIG. 9, since the status of the mobile station is set to be asynchronous when the mobile station is initialized, the automatic gain control is performed in the out-of-sync status (SlOO). Then, it is judged whether the synchronization signal generating section 300 acquires the synchronization with respect to the base station or not (SI lO). Here, since the process of judging whether the synchronization is acquired or not is already known to the public, the detailed description about this is omitted in the exemplary embodiment of the present invention.

[90] When the synchronization signal is received from the synchronization signal generating section 300 through the synchronization acquisition, the status of the mobile station is transferred to the in-sync status from the out-of-sync status (S 120), and thereafter the automatic reception gain control in accordance with the synchronous mode is performed. First, the analog processing section 100 converts the received RF signal to the digital signal (S 130). The signal selector 210 receives the converted digital signal and the synchronization signal output form the synchronization signal generating section 300 (S 140), and selects a digital signal to be used to calculate a power (S 150).

[91] Then, the power calculator 221 calculates the power with respect to the selected digital signal (S 160). Comparing the reference power with the power calculated at the power calculator 221, the power difference calculator 222 calculates the amount of power variation (S 170). The power accumulator 223 adds the amount of power variation that is calculated at the power difference calculator 222 to the power that was already calculated, and calculates an accumulation power to be newly reflected on the signal gain control input to the analog processing section 100.

[92] The power limiter 224 limits the newly calculated accumulation power to output the power level signal, and the power controller 226 determines the reception gain based on this and generates a signal required to perform the gain control (S 180). Thereafter, the synchronization signal generating section 300 judges whether the synchronization with respect to the base station is lost or not (S 190). If the synchronization is lost, the status of the mobile station is transferred to the out-of-sync status from the in-sync status and the reception gain is controlled in the asynchronous mode. However, if the synchronization is not lost, the mobile station controls the reception gain as described above while maintaining the in-sync status.

[93] The exemplary embodiment of the present invention as described above is not necessarily implemented only through the method and apparatus. The exemplary embodiment of the present invention can be realized through a program or through a recording medium on which the program is recorded having the function corresponding to the construction of the exemplary embodiment of the present invention. This modification from the exemplary embodiment of the present invention can be easily realized to a person of ordinary skill in the art.

[94] While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

[1] A method of automatic reception gain control in a mobile station, the method comprising: judging whether the mobile station is in an in-sync status or an out-of-sync status; receiving a digital signal and a synchronization signal synchronized to a base station with respect to the digital signal and selecting a digital signal of a duration that is used to calculate a power from the digital signal when the mobile station is in the in-sync status as a result of the judging; calculating the power of the selected digital signal of the duration and calculating an amount of power variation through a difference between a reference power and the calculated power; and determining a reception gain based on the calculated amount of power variation and outputting a control signal for controlling the reception gain.

[2] The method of automatic reception gain control of claim 1, wherein the selecting of the digital signal comprises: arbitrarily selecting a signal to be used to calculate the power during a predetermined time irrespective of the synchronization signal to be input when the mobile station is in the out-of-sync status; and performing a synchronization acquisition process for acquiring the synchronization signal.

[3] The method of automatic reception gain control of claim 2, wherein when the status of the mobile station is transferred to the in-sync status by the synchronization acquisition, a signal to be used to calculate the power is selected based on the digital signal that is input in a time duration designated within a time duration provided based on the input synchronization signal.

[4] The method of automatic reception gain control of claim 2, wherein: the status of the mobile station is transferred to the in-sync status from the out- of-sync status when the mobile station acquires the synchronization signal; and the status of the mobile station is transferred to the out-of-sync status from the in-sync status when the mobile station loses the synchronization signal.

[5] The method of automatic reception gain control of claim 1, wherein the determining of the reception gain comprises: calculating an accumulation power by adding the amount of variation in power to the power that was previously calculated; outputting the power level signal after restricting the power by comparing the calculated accumulation power with a predetermined operation range; outputting a control signal for controlling low noise amplification by filtering the power level signal; and receiving the power level signal and the control signal and outputting a signal that is necessary to perform the gain control.

[6] The method of automatic reception gain control of claim 5, wherein the outputting of the power level signal comprises: outputting the power level signal by limiting the calculated accumulation power to a predetermined maximum threshold value, when the calculated accumulation power exceeds the predetermined maximum threshold value; and outputting the power level signal by limiting the calculated accumulation power to a predetermined minimum threshold value, when the calculated accumulation power is less than the predetermined maximum threshold value.

[7] An apparatus for automatic reception gain control in a mobile station, the apparatus comprising: an analog processing section that receives a radio frequency signal, a feedback signal for gain control, and a feedback signal for low noise amplification control, converts the input signal to a digital signal, and outputs the digital signal; a synchronization signal generating section that receives the digital signal output from the analog processing section and outputs the synchronization signal by ensuring time synchronization; and a reception gain controlling section that receives the digital signal and the synchronization signal, selects a signal to be used in power calculation from the digital signal to calculate a reception power, and outputs the feedback signal for gain control and the feedback signal for low noise amplification control to the analog processing section using the calculated reception power.

[8] The apparatus for automatic reception gain control of claim 7, wherein the reception gain controlling section comprises: a signal selector that receives the synchronization signal generated from the synchronization signal generating section and selects the signal to be used in power calculation from the digital signal to be output from the analog processing section; and a reception gain generator that calculates a power by using the selected digital signal and determines the reception gain based on the calculated power.

[9] The apparatus for automatic reception gain control of claim 8, wherein the signal selector selects the signal to be used to calculate the power by using the synchronization signal, when the mobile station is in the in-sync status, and the signal selector arbitrarily selects a signal to be used to calculate the power irrespective of the synchronization signal, when the mobile station is in the out- of- sync status.

[10] The apparatus for automatic reception gain signal of claim 9, wherein the reception gain generator comprises: a power calculator that receives the digital signal that is selected at the signal selector and calculates an average power of the digital signal; a power difference calculator that calculates a difference between the power calculated at the power calculator and a reference power to calculate an amount of power variation; a power accumulator that adds the amount of power variation calculated at the power difference calculator to the power that was previously calculated to calculate an accumulation power that is reflected on a received signal; a power limiter that limits the power to output the power level signal after judging whether the accumulation power reflected on the received signal is in an operation range, the accumulation power being calculated at the power accumulator; a low noise amplification filter that filters the power level signal output from the power limiter and outputs a control signal for controlling the low noise amplification; and a power controller that receives the power level signal output from the power limiter and the control signal output from the low noise amplification filter and generates the feedback signal for gain control and the feedback signal for low noise amplification control.

[11] The apparatus for automatic reception gain control of claim 10, wherein: the power limiter limits the calculated accumulation power to a predetermined maximum threshold value to output the power level signal, when the calculated accumulation power exceeds the predetermined maximum threshold value; and the power limiter limits the calculated accumulation power to a predetermined minimum threshold value to output the power level signal, when the calculated accumulation power is less than the predetermined minimum threshold value.

[12] The apparatus for automatic reception gain control of claim 7, wherein the analog processing section comprises: a low noise amplifier that receives the radio frequency signal and the feedback signal for low noise amplification control to reflect a low noise amplification gain thereon; a gain amplifier that receives the radio frequency signal and the feedback signal for gain control on which the low noise amplification gain is reflected, reflects a reception gain thereon, and outputs the radio frequency signal on which the reception gain is reflected; and an analog-digital converter that receives the radio frequency signal on which the reception gain is reflected, converts the input radio frequency signal to a digital signal, and outputs the converted digital signal.