KR100653174B1 - Apparatus and method for power controlling downlink closed loop which is adaptative environment - Google Patents

Abstract

An environmentally adaptable downlink closed loop power control device and a method thereof are provided to decide on the current area by calculating a reception Rician factor K, and to confirm the type of data received from the area to control downlink power according to the confirmed data, thereby minimizing inter-channel interference and inter-beam interference. An SIR(Signal to Interference Ratio) calculator(21) combines a CPICH(Common Pilot Channel), a DPCCH(Dedicated Physical Control Channel), and an S-CCPCH(S-Common Control Physical Channel) according to environmental conditions, as a signal is received from a satellite/base station(10), and calculates an attenuated SIR undergone on the channels. A comparator(22) compares the calculated SIR with a target SIR set in open loop power control. A TPC(Transmit Power Control) generator(23) generates a TPC command according to the compared results.

Description

Environment-adaptive downlink closed loop power control device and its method {Apparatus and method for power controlling downlink closed loop which is adaptative environment}

1 is a configuration diagram of an embodiment of a mobile communication system to which the present invention is applied;

2 is a detailed configuration diagram of an embodiment of a mobile communication system to which the present invention is applied;

3 is an exemplary explanatory diagram showing a relative timing relationship of pilot channels used in the present invention;

4 is a flowchart illustrating an embodiment of an environmentally adaptive downlink closed loop power control method according to the present invention;

5 is a diagram illustrating an embodiment of a frame structure of a DPCH used in the present invention;

6 is a diagram illustrating an embodiment of a frame structure of a CPICH used in the present invention;

7 is an exemplary diagram illustrating a frame structure of S-CCPCH used in the present invention.

* Explanation of symbols for the main parts of the drawings

10: satellite / base station 11: delay compensation unit

12: TPC decoder 13: transmission power determining unit

20: terminal 21: SIR calculation unit

22: comparator 23: TPC generation unit

The present invention relates to an environment-adaptive downlink closed loop power control apparatus and a method thereof, and more particularly, in downlink power control for transmitting a signal and transmission power control command from a user terminal to a base station such as a satellite or a central station By determining the received Rixian factor (K) to determine the current region (country or downtown), and by checking the type (voice or packet) of data received in the region to control the downlink power accordingly Environment adaptation to control downlink power to maximize the use of finite transmit power to suit the desired service area while minimizing inter beam interference and inter channel interference The present invention relates to a downlink closed loop power control device and a method thereof.

The goal of the next generation satellite or mobile communication system is to provide a wide variety of communication services to anyone, anywhere, anytime. The proposal for the combination of global system for mobile communication (GSM) and wideband code division multiple access (W-CDMA) has gained strong persuasion, and several proposals supporting W-CDMA provide high quality voice and multimedia services. IMT-2000 (International Mobile Telecommunications-2000) has been adopted to provide ground mobile services in many countries.

The W-CDMA system having a pilot symbol structure of Satellite-Universal Mobile Telecommunications Systems (S-UMTS) and Terrestrial-UMTS (T-UMTS) is an important feature of asynchronous cell-to-cell. In addition, in order to improve link capacity, a synchronous demodulation scheme is adopted for uplink and downlink.

The power control technology of the SAT-CDMA system, proposed as one of the IMT-2000 satellite transmission standards, includes both up-down closed loop power control and up-open loop power control, like the terrestrial IMT-2000 system of the 3rd Generation Partnership Project (3GPP). .

In general, closed loop power control is to maintain the received power or the received signal-to-noise ratio at a target value determined by the system. To this end, the receiver generates a power control command by comparing the magnitude of the current received power or signal-to-noise ratio with the target value and transmits it to the transmitter. The transmitter controls the transmit power accordingly.

SAT-CDMA is a LEO / GEO mobile satellite system, which has a large channel characteristic compared to terrestrial systems because the signal delay time between the base station and the terminal reaches tens / hundreds of msec. Therefore, for efficient power control in SAT-CDMA, an algorithm capable of controlling power in advance by predicting a future channel change in consideration of a long delay time is required.

As a first conventional technology for overcoming the problems caused by such delay time in a loop, US Patent No. 6,493,541 (Transmitted Power Control Time Delay Compensation In A Wires Systems) is disclosed.

The patent relates to a method for estimating the received power after the delay time in the loop and generating the power control command based on the delay time in the loop until the current power control command is reflected in the received power.

However, the patent has a problem that can not solve the degradation of the performance caused by the channel change during the delay time in the loop.

As a second conventional technology for solving the problems of the first conventional technology, Korean Patent No. 10-2004-0047907 (name of the invention: a closed loop power control device and method thereof in a satellite mobile communication system) is disclosed. have.

The second conventional technique relates to a method for compensating for severe performance deterioration in terms of loop stability by resolving performance deterioration caused by channel change during in-loop latency.

However, the above two conventional techniques do not first consider the finite variable of satellite or base station transmission power in terms of radio resource management, and secondly, only voice-oriented downlink without considering the geographical conditions. By providing only the power control technique, there is a problem that can not be applied to the packet-based communication system.

The present invention has been proposed to solve the above problems, and in the downlink power control for transmitting a signal and a transmission power control command from a user terminal to a base station such as a satellite or a central station, a reception Rixian factor (K). Determine the current region (country or downtown), check the type of data (voice or packet) received in the region and control the downlink power accordingly, thereby inter-interference interference and mutual An environmentally adaptive downlink closed loop power control device and method for controlling downlink power by using a finite transmission power to a desired area while minimizing inter channel interference and a method thereof are provided. The purpose is to provide.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The apparatus of the present invention for achieving the above object is, in the environment adaptive downlink closed loop power control device, a common pilot channel (CPICH), dedicated physical control channel (DPCCH) and S as receiving a signal from the satellite / base station SIR calculation means for calculating a signal-to-interference ratio (SIR) experienced by the channel by combining S-Common Control Physical CHannel (CCPCH) according to environmental conditions; Comparison means for comparing the calculated SIR with the target SIR set in the open loop power control; And TPC generating means for generating a TPC (Transmit Power Control) command according to the comparison result in the comparing means.

On the other hand, the method of the present invention, in the environment adaptive downlink closed loop power control method, by measuring the interference of the CPICH (Common Pilot CHannel), DPCCH (Dedicated Physical Control CHannel) received signal interference of the received signal every one frame period Receiving signal interference calculation step of calculating; Calculating a Lysian factor; Comparing the calculated Risian factor with a threshold to determine a current location as a rural area when the Risian factor exceeds a threshold, and determining a current location as a downtown area when the Risian factor does not exceed a threshold; A SIR calculation step of calculating a signal-to-interference ratio (SIR) in the channel by combining CPICH, DPCCH and S-Common Control Physical CHannel (S-CCPCH) according to the type of received data in the corresponding region; And determining the uplink transmission power according to the calculated SIR.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of an embodiment of a mobile communication system to which the present invention is applied.

As shown in FIG. 1, the mobile communication system to which the present invention is applied compensates for a round trip delay time between satellites and base stations, and decodes a TPC (Transmit Power Control) command received from the terminal 20 to increase power. After determining whether to lower, the satellite / base station 10 to determine the transmission power to be transmitted by the satellite / base station antenna, and transmits a signal to the terminal 20 according to the determined transmission power, and the satellite / base station 10 Calculate the attenuation experienced by the channel as it receives a signal from it, i.e. combine the Common Pilot CHannel (CPICH), Dedicated Physical Control CHannel (DPCCH) and S-Common Control Physical CHannel (S-CCPCH) to match the current SIR. After calculating (Signal-to-Interference Ratio), compare the target SIR set in the open-loop power control with the calculated SIR to predict the power to come in after the next round trip delay time. And a terminal 20 for transmission to the satellite / base station 10.

Here, the satellite / base station 10 decodes a TPC (Transmit Power Control) command received from the delay compensator 11 and the terminal 20 to compensate for the delay time during the round trip delay time between the satellite / base station. According to the TPC decoder 12 for determining the transmission power by determining the TPC command decoded by the TPC decoder 12 and the transmission power determined by the transmission power determination unit 13. And a downlink transmitter 14 for transmitting a signal to the terminal 20.

Meanwhile, the environmentally adaptive downlink closed loop power control device (terminal) according to the present invention calculates the attenuation experienced in the channel as it receives a signal from the satellite / base station 10, that is, a common pilot channel (CPICH) and a DPCCH. SIR calculation unit for combining the Dedicated Physical Control CHannel and S-Common Control Physical CHannel (S-CCPCH) according to environmental conditions (region and data) to calculate the current Signal-to-Interference Ratio (SIR) (21). ), A comparator 22 for comparing the calculated SIR with the target SIR set in the open loop power control, and a TPC generation unit 23 for generating a TPC command according to the comparison result of the comparator 22. Include.

Here, the TPC generation unit 23 generates a TPC command that increases power by the difference when the calculated SIR does not exceed the target SIR as a result of the comparison in the comparator 22, and the calculated SIR is the target SIR. It is desirable to generate a TPC instruction that reduces the power by the difference if it exceeds.

2 is a detailed configuration diagram of an embodiment of a mobile communication system to which the present invention is applied.

As shown in FIG. 2, the pilot channels used in the present invention include CPICH, DPCH, and S-CCPCH, and the like, and receive and receive in the environment adaptive downlink closed loop power control device (terminal) according to the present invention. The reception power of the corresponding channel is measured according to the type of data.

3 is a diagram illustrating an example of a relative timing relationship of pilot channels used in the present invention.

,

, 및

는 i번째 슬롯 동안 위성/기지국 단말기 간의 거리 동안 겪는 채널이득을 의미한다. 여기서, 슬롯의 길이는 10 ms이다. As shown in FIG. 3,

,

, And

Denotes the channel gain experienced during the distance between the satellite / base station terminals during the i-th slot. Here, the length of the slot is 10 ms.

4 is a flowchart illustrating an embodiment of an environmentally adaptive downlink closed loop power control method according to the present invention.

First, by setting the following four environments in consideration of finite transmission power and geographical conditions, a smooth communication service is provided using the finite transmission power of a satellite or a base station to the maximum.

1. Channels used for power control when receiving packet-oriented services in rural areas: CPICH and DPCCH (1.2)

2. Channels used for power control when receiving packet-oriented services in urban areas: DPCCH, CPICH, and S-CCPCH (1.4)

3. Channel used for power control when receiving voice-oriented services in rural areas: DPCCH (0.2)

4. Channels used for power control when receiving voice-oriented services in urban areas: CPICH and DPCCH (1.2)

Here, when the normalized reception power of the CPICH channel is 1, the pilot reception power of the DPCCH and the S-CCPCH is both 0.2. Therefore, the numerical values in parentheses mean the sum of received powers of channels required for SIR prediction.

As described above, the background of selecting channels in each case is that packet-based communication requires a higher SIR, that is, a lower frame error rate (FER), than a voice-based communication. It is selected to be advantageous for packet-based communication in urban areas, which can reduce the transmission power.

Thereafter, rural areas have fewer users than urban areas, so even if more power is used to increase the transmission power of satellites or base stations, interference to other users is relatively less active than urban areas. By using each channel in consideration of the ranking, it has excellent performance both in terms of efficiently using the finite transmit power of each satellite or base station and in terms of channel prediction complexity.

Next, an environmental adaptive downlink closed loop power control method according to the present invention will be described.

First, as receiving the downlink received signal, the interference of the DPCH received signal is measured at predetermined time intervals using Equation 1 below to calculate the interference of the received signal every one frame period (401, 402).

Here, d (t), g (t), p (t), and s (t) denote DPCH received complex symbols, channel gain, transmit power, and pilot symbols of DPCCH, respectively.

Thereafter, the presence or absence of the CPICH received signal is checked (403).

As a result of the check 403, the interference of the CPICH received signal is measured at predetermined time intervals as the received signal exists to calculate the interference of the received signal every one frame period (404). At this time, if the received signal does not exist, the process proceeds to "405" without calculating the interference of the received signal. In addition, the interference of the received signal is calculated in the same manner as in [Equation 1].

Then, in order to obtain geographic information, the Risian factor is calculated using Equation 2 below (405).

Using the probability density function above, find the Lysian factor.

는 각각 원하는 신호성분, 직접파 성분, 그리고 원하는 성분의 평균 제곱을 의미한다.Where r and C and

Denotes the desired signal component, the direct wave component, and the mean square of the desired component, respectively.

Then, the calculated Lysian factor (gamma_K-factor) is compared with a threshold (406).

In the comparison result 406, if the Risian factor exceeds a threshold, the current location is determined as a rural area and the process proceeds to step 407. If the Risian factor does not exceed the threshold, the current location is determined as a downtown area. Proceed to step "413". Here, the threshold is adjustable according to the system situation.

Thereafter, as the current location is a rural area, the format of the received data is checked (407).

As a result of the check 407, if the packet-based service corresponds to the "CASE 1", the received signal interference combination is generated using the received power experienced by the DPCCH and the CPICH channel to calculate the SIR, and the uplink transmit power to be transmitted to the satellite / base station. Determine (408 to 410).

를 의미하며,

,

는

을 만족시키는 임의의 변수이다.Here, the received signal interference combination is

Means,

,

Is

Any variable that satisfies

On the other hand, if the check result 407, voice-based service (411), the SIR is calculated using Equation 3 below using the received power of the DPCCH channel corresponding to the "CASE 3" and the satellite / base station The uplink transmission power to be transmitted is determined (409, 410).

Meanwhile, as the current location is the downtown area, the format of the received data is checked (413).

As a result of the check 413, if it is a packet-based service, it corresponds to the "CASE 4" requesting the highest received SIR and the lowest FER at the same time, and checks whether the S-CCPCH channel is received to increase the received SIR (414). .

As a result of the check 414, if the S-CCPCH channel is received, the SIR is calculated through Equation 3 below by creating a received signal interference combination using the received power experienced by the DPCCH, CPICH and S-CCPCH channel (415). , 417), and proceeds to the "410" process, and if the S-CCPCH channel is not received, calculates the SIR through Equation 3 below by creating a received signal interference combination using the received power experienced by the DPCCH and CPICH channels. (416, 417), and proceeds to the "410" process.

를 의미하며,

,

,

는

을 만족시키는 임의의 변수이다.Here, the received signal interference combination is

Means,

,

,

Is

Any variable that satisfies

,

그리고

은 각각 직교인자(orthogonality factor), 채널 이득, 그리고 CPICH의 파일럿 성분을 의미한다.here,

,

And

Denotes an orthogonality factor, channel gain, and pilot component of the CPICH, respectively.

As a result of the check 413, if it is a voice-based service, the process proceeds to step “408” to perform the following process. In other words, it handles the same as packet-based services in rural areas.

5 is a diagram illustrating an embodiment of a frame structure of a DPCH used in the present invention.

As shown in FIG. 5, the SIR estimation is performed using a pilot symbol in which the control channel of the DPCCH and the data channel of the DPDCH are time-division multiplexed and transmitted for SIR prediction estimation. . The chip rate is 3.84 Mcps, each slot has 2560 chips and 15 slots have one frame.

6 is a diagram illustrating an embodiment of a frame structure of a CPICH used in the present invention.

As shown in FIG. 6, this channel is used for the downlink physical layer with a fixed symbol rate of 30 kbps and has a symbol pattern known to both the satellite / base station and the terminal.

Therefore, it can be used very easily for channel prediction. That is, in order to estimate the SIR channel change rate, the channel estimation is performed by transmitting pilot symbols in a predefined pattern known to the transmitter and the receiver.

In addition, since the CPICH channel is transmitted without performing power control at the transmitter, the CPICH channel is very useful for recovering data experienced by the receiver and for estimating frequency offset.

7 is an exemplary diagram illustrating a frame structure of S-CCPCH used in the present invention.

As shown in FIG. 7, the channel change rate is estimated using the pilot symbols of the S-CCPCH for SIR estimation. The background of adopting the channel in the present invention is because it is similar to the data rate of the DPCH and power control can be performed in the same manner.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

As described above, in the downlink power control in which a user terminal transmits a signal and a transmission power control command to a base station such as a satellite or a central station, the present region may be calculated by calculating a reception factor (K). Internal beam interference and inter-channel interference by determining the type of data (voice or packet) received in the region and controlling downlink power accordingly. While minimizing interference, it is possible to control downlink power by maximally using a finite transmission power for a desired service in an appropriate region.

Claims (8)

In the environment adaptive downlink closed loop power control device, Attenuation experienced in the channel by combining Common Pilot CHannel (CPICH), Dedicated Physical Control CHannel (DPCCH), and S-Common Control Physical CHannel (S-CCPCH) according to environmental conditions upon receiving signals from satellite / base stations. SIR calculating means for calculating -to-Interference Ratio); Comparison means for comparing the calculated SIR with the target SIR set in the open loop power control; And TPC generation means for generating a TPC (Transmit Power Control) command according to the comparison result in the comparison means Environment adaptive downlink closed loop power control device comprising a. The method of claim 1, The environmental conditions, Combine CPICH and DPCCH for packet data in rural areas, combine DPCCH, CPICH, and S-CCPCH for packet data in urban areas, combine DPCCH for voice data in rural areas, and CPICH for voice data in urban areas. An environmentally adaptive downlink closed loop power control device comprising combining a DPCCH. The method according to claim 1 or 2, The TPC generating means, Generating a TPC command that increases power by the difference if the calculated SIR does not exceed the target SIR; and generates a TPC command that reduces power by the difference when the calculated SIR exceeds the target SIR. Environmental adaptive downlink closed loop power control device. In the environment adaptive downlink closed loop power control method, A received signal interference calculation step of measuring interference of a common pilot channel (CPICH) and a dedicated physical control channel (DPCCH) received signal and calculating the interference of the received signal every one frame period; Calculating a Lysian factor; Comparing the calculated Risian factor with a threshold to determine a current location as a rural area when the Risian factor exceeds a threshold, and determining a current location as a downtown area when the Risian factor does not exceed a threshold; A SIR calculation step of calculating a signal-to-interference ratio (SIR) in the channel by combining CPICH, DPCCH and S-Common Control Physical CHannel (S-CCPCH) according to the type of received data in the corresponding region; And Determining an uplink transmission power according to the calculated SIR Environment adaptive downlink closed loop power control method comprising a. The method of claim 4, wherein The SIR calculation step, SIR is calculated by combining CPICH and DPCCH for packet data in rural areas, and SIR is calculated by combining DPCCH, CPICH, and S-CCPCH for packet data in urban areas. And calculating the SIR by combining the CPICH and the DPCCH when the voice data is in the urban area. The method according to claim 4 or 5, The received signal interference calculation step, An environmentally adaptive downlink closed loop power control method characterized by calculating using Equation A below. Equation A

Here, d (t), g (t), p (t), and s (t) denote DPCH received complex symbols, channel gain, transmit power, and pilot symbols of DPCCH, respectively. The method of claim 6, The Lysian factor calculation step, An environmentally adaptive downlink closed loop power control method characterized by calculating using Equation B below. Equation B

Using the probability density function above, find the Lysian factor.

Where r and C and

Denotes the desired signal component, the direct wave component, and the mean square of the desired component, respectively. The method of claim 7, wherein The SIR calculation step, An environmentally adaptive downlink closed loop power control method characterized by calculating using Equation C below. Equation C

here,

,

And

Denotes an orthogonality factor, channel gain, and pilot component of the CPICH, respectively.

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