• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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    • 专利摘要:
    PURPOSE: A method for adaptively transmitting a signal in a wireless communication system and an apparatus therefor are provided to vary a transmission parameter of the signal according to an attenuation state of a communication channel. CONSTITUTION: An attenuation quantity estimator(15) estimates a channel attenuation quantity of a wireless communication channel. A control quantity decider(16) sets a coding rate, a modulation level, and a transmission power of a signal to be transmitted on the basis of the estimated channel estimation quantity. An encoder(12) encodes the signal according to the set coding rate. A modulator(13) modulates the signal according to the set modulation level. A power controller(14) transmits the encoded and modulated signal according to the set transmission power.
    公开号:KR20030034262A
    申请号:KR1020010048180
    申请日:2001-08-10
    公开日:2003-05-09
    发明作者:양우석；김수영
    申请人:한국전자통신연구원；
    IPC主号:
    专利说明:

    Adaptive transmission method in wireless communication system and device
    [5] The present invention relates to a method and apparatus for adaptively transmitting a signal in a wireless communication system, and more particularly, to an adaptive signal transmission method for varying a transmission parameter of a signal according to attenuation state of a communication channel in a wireless communication system. To the device.
    [6] In a mobile communication channel of a wireless communication system, signal attenuation occurs due to surrounding buildings or terrain. In particular, in a mobile communication channel, this attenuation changes over time due to the movement of a moving object. Since the signal sent from the transmitter is aggravated by this attenuation, reliable communication requires a strong signal transmission or a channel coding method with strong error correction capability.
    [7] In order to meet the required bit error rate (BER) in fixed transmission systems using fixed transmission power or fixed channel coding methods, the transmission power value or coding method should be set for the worst case attenuation. In this case, when the channel is good, unnecessary transmission power is used or unnecessary coding redundancy is used, thereby reducing the power efficiency of the overall system or the bandwidth efficiency of the system.
    [8] Therefore, in recent years, the transmission parameters (code rate, modulation level, transmission power, etc.) of a signal are adaptively changed according to a change in attenuation generated in a mobile communication channel, that is, a Rayleigh channel to satisfy a required quality of service such as BER. Alternatively, researches on efficient transmission methods in terms of power and bandwidth have been made.
    [9] Techniques for a conventional adaptive signal transmission method include the following.
    [10] 1) Korean Patent Application No. 98-11997
    [11] 2) US Patent Registration Number US 6137841
    [12] 3) US Patent Registration Number US 5541955
    [13] Prior art 1) relates to an "adaptive channel code / decoding method and a code / decoding device thereof", which selectively uses an encoder, that is, a convolutional encoder and a turbo encoder, according to the BER and data frame length required for a communication service. send. However, only the type of code used and the code rate are varied so that only the required service conditions are satisfied, and the method of maximizing bandwidth efficiency is not considered.
    [14] Prior art 2) relates to " signal power adaptation in QAM communication system " and adjusts the transmit power to a predesigned operable power in accordance with the QAM level in a quadrature amplitude modulation (QAM) communication system. However, this only implements scaling the QAM signal to match the system's maximum average transmit power for each modulation level, and does not describe the maximum implementation of the transmission bandwidth efficiency.
    [15] Prior art 3) relates to an "adaptive data rate modem" and to a method of adapting a code and modulation level to a channel situation. However, this is limited to the structure of the lattice code modulation, and does not propose a method for allocating codes and modulation levels to obtain the maximum data rate, and does not provide an adaptation scheme for power control, which is essential in the current mobile communication environment.
    [16] Therefore, the technical problem to be achieved by the present invention is to solve the above-described problems, and satisfies the required BER by appropriately allocating a code, modulation level, and transmission power of a transmission signal according to attenuation of a communication channel in a wireless communication system. While trying to get the maximum average bandwidth efficiency.
    [1] 1 is a block diagram illustrating a structure of an apparatus for adaptively transmitting a signal and a structure of a receiving side in a wireless communication system according to an exemplary embodiment of the present invention.
    [2] 2 is a diagram illustrating channel information in a method for adaptively transmitting a signal in a wireless communication system according to an exemplary embodiment of the present invention. Is a graph showing the code, modulation level, and transmission power allocation scheme.
    [3] 3 is a flowchart illustrating an operation sequence of a transmitter according to a method for adaptively transmitting a signal in a wireless communication system according to an exemplary embodiment of the present invention.
    [4] 4 is a flowchart illustrating an operation sequence of a receiving end in a method for adaptively transmitting a signal in a wireless communication system according to an exemplary embodiment of the present invention.
    [17] According to an aspect of the present invention, there is provided a method for adaptively transmitting a signal, comprising: estimating channel attenuation information of a wireless communication channel; Setting a code rate, modulation level, and transmission power of a signal to be transmitted based on the estimated channel attenuation information; Encoding a signal according to the set code rate; Modulating a signal according to the set modulation level; And transmitting a coded and modulated signal according to the transmission power set above.
    [18] Channel attenuation information when transmitting at code rate R i and modulation level M j in the setting step The transmit power P varies according to ) So that the received SNR value is SNR ij Set to. here Is a Rayleigh random variable , SNR ij is " 0 " and is a received SNR value that satisfies the required BER when transmitted from additive white gaussian noise (AWGN) at a code rate R i and modulation level M j .
    [19] In addition, the setting step is a plurality of code rate And modulation level Combination To transmit the average data rate at a given average transmit power condition using the method of transmit power control described above. According to code rate R ( ), Modulation level M ( ), Transmit power P ( ).
    [20] Code rate, modulation level, and transmission power setting method are as follows. Average transmit power to use first during system initialization Combination of transfer parameters to use Given the boundary value that determines the code rate, modulation level, and transmit power type. This is determined. These thresholds have the transmit power form described above, and average transmit power conditions. Bandwidth efficiency while satisfying Are the maximum values. [R / B] k is the bandwidth efficiency when the transmission combination (R i (k) , M j (k) ) is used, and is the number of pure data per modulation symbol. Then, in the actual transmission phase, this threshold And current channel estimate The code rate, modulation level, and transmit power value are determined by E.g < If 1 , no data transfer takes place When the code rate is R ( ) = R i (k) , M ( Modulation level with) = M j (k) , Transmit power is allocated.
    [21] According to another aspect of the present invention, an apparatus for adaptively transmitting a signal in a wireless communication system includes: an attenuation estimator estimating an amount of channel attenuation of a wireless communication channel; A control amount determiner for setting a code rate, modulation level, and transmission power of a signal to be transmitted based on the estimated channel attenuation amount; An encoder for encoding a signal according to the set code rate; A modulator for modulating a signal according to the set modulation level; And a power controller for transmitting a coded and modulated signal according to the set transmission power.
    [22] DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
    [23] 1 illustrates a structure of an apparatus for adaptively transmitting a signal (hereinafter, referred to as an adaptive transmission apparatus) in a wireless communication system according to an exemplary embodiment of the present invention.
    [24] As shown in FIG. 1, the adaptive transmission device 10 according to the embodiment of the present invention is connected to the reception device 30 through a channel and an additional system 20, and a buffer for storing an input signal. (11), an encoder 12 for encoding the signal, a modulator 13 for modulating the encoded signal, a power controller 14 for adjusting the power of the modulated signal, and an attenuation estimator 15 for estimating the attenuation of the channel. And a control amount determiner 16 which controls the encoder 12, the modulator 13 and the power controller 14 according to the channel attenuation situation to obtain the maximum bandwidth efficiency according to the channel condition.
    [25] In an embodiment of the present invention, the encoder 12 has a plurality of code rates. The modulator 13 has a plurality of modulation levels Has The control amount determiner 16 stores a table in which a code rate, a modulation level, and a transmission power value are matched to obtain the maximum bandwidth efficiency according to the channel attenuation information. The control amount determiner 16 is provided from the attenuation estimator 15. The table is searched based on the attenuation information to select the code rate and modulation level and to set the transmit power value. As described above, the transmission signal in which the coding rate, modulation level, and transmission power are adaptively changed according to the channel attenuation situation is transmitted through the channel and the additional system 20. Here, the channel and additional system 20 includes a transmit antenna and a receive antenna.
    [26] The signal transmitted through the channel and the additional system 20 is received by the receiving device 30, and the receiving device 30 receives the signal based on the code, modulation level information, or attenuation information of the transmitting side provided through the channel. The demodulator 31 includes a demodulator 31 for demodulating corresponding to the modulation level, a decoder 32 for decoding the demodulated signal corresponding to the coding rate of the transmitting side, and a buffer 33 for storing the decoded signal.
    [27] In the adaptive transmission apparatus according to the embodiment of the present invention having such a structure, a code rate, a modulation level, and a transmission power value for obtaining maximum bandwidth efficiency according to channel attenuation information are obtained as follows.
    [28] 2, in the adaptive transmission method according to the embodiment of the present invention, channel attenuation information A graph showing a symbol, a modulation level, and a transmission power allocation scheme is shown.
    [29] In the embodiment of the present invention, the maximum bandwidth efficiency is obtained by optimally allocating the code rate, modulation level, and transmission power according to the channel attenuation information, and the transmission power control scheme used at this time satisfies the required BER. .
    [30] First, a description is given of satisfying the required BER by performing power control so that the reception SNR becomes the target reception SNRij value in one combination of modulation level and code rate.
    [31] In an embodiment of the invention, the encoder Supports code rate of modulator It supports modulation level of. In this case, there is a received signal to nosie ratio (SNR) value that satisfies the target BER in additive white gaussian noise (AWGN) for each combination of code rate and modulation level {R i , M j }. . When this value is referred to as the target reception SNR ij , power control is performed so that the reception SNR becomes the target reception SNR ij value even in a fading channel, thereby satisfying the required BER.
    [32] Specifically, if the transmission power, the channel attenuation value, the power density and bandwidth of the unidirectional noise are P, G, NO , and B, respectively, when the power control is not performed (when the transmission power P is fixed), the received SNR is Becomes This received SNR varies over time by the channel attenuation value G.
    [33] On the contrary, when the transmit power is changed according to the channel attenuation state without fixing the transmit power P, P ( Send transmit power) Becomes At this time, the variable transmit power P ( ) Satisfies the purpose received SNR ij When the value is received, the received SNR value always satisfies the target received SNR ij .
    [34] end If you use Becomes here And Is the probability density function in Rayleigh attenuation channels. Has
    [35] Thus, the required BER and power control so that the received SNR object received SNR ij values from one modulation level and the combination of code rate {R i, M j} can be satisfied.
    [36] Next, the channel situation, that is, channel attenuation information. According to code rate , And modulation level The optimal allocation of the transmission combinations of s to obtain the maximum average bandwidth efficiency is described.
    [37] Code rate And modulation level The number K of the combination of to be. Where for each {R i , M j } the pure data rate per modulation symbol is Becomes
    [38] [R / B] ij can be expressed as [R / B] k by combining each code rate and modulation level in the order of low data rate and giving subscript from 1 to K. Satisfies. Similarly, the coding rate, modulation level, and target received SNR corresponding to [R / B] k are represented by R i (k) , M j (k) , and SNR k , respectively.
    [39] If the channel is bad, no data should be sent or a combination of low data rates should be used. On the other hand, when the channel is good, a transmission combination with a high data rate should be used for efficient transmission. That is, as a transmission combination allocation method for increasing the pure data rate About < i does not send data About To transmit data with the data efficiency of transmission. When such a transmission parameter allocation method is used, the average bandwidth efficiency is expressed by Equation 1 below.
    [40]
    [41] When using the power control scheme that satisfies the required BER for the above transmission parameter allocation scheme, the following Equation 2, which is an average transmission power condition, must be satisfied.
    [42]
    [43] P ( ) = 0, < One ,
    [44] Therefore, the boundary value for selecting the code rate, modulation level, and transmission power to obtain the maximum bandwidth efficiency while satisfying the required BER Should be optimized. These bounds Equation 2 satisfies Equation 2 while maximizing Equation 1, and is obtained by using the Lagrange multiplier.
    [45]
    [46] Is, 1 is a value that satisfies the following equation (4).
    [47]
    [48] Thus, the boundary value used for code rate, modulation level, and transmission power allocation that satisfies the required BER and obtains the maximum average bandwidth efficiency. The code rate, modulation level and transmission power are allocated as shown in FIG.
    [49] For example, referring to FIG. 2, the estimated channel attenuation information end < If 1 , no data transfer takes place 1 < < 2 , the code rate is R 1 , the modulation level is M 1 , and the transmit power is Is assigned to.
    [50] In other words, k < < when k + 1 il of code rate R k code, M k of modulation levels, Transmit power is allocated.
    [51] As described above, in order to obtain maximum bandwidth efficiency, the possible channel attenuation information is divided into a plurality of intervals and the boundary value in each interval. Optimally allocates the code rate, modulation level, and transmit power for each interval, and then transmits data as follows.
    [52] 3 illustrates an operation sequence of a transmitting end, that is, a transmitting device, according to an adaptive transmission method according to an embodiment of the present invention.
    [53] First, as described above, the target received SNR for each code and modulation level is The boundary value that determines the code and bounds the code, modulation level, and transmit power accordingly. Determine (S100). The values thus determined are, for example, tabulated and stored in an internal memory (not shown) of the control amount determiner 16 or in a separate memory.
    [54] Next, data to be transmitted, such as voice and text (hereinafter referred to as data), is input to the buffer 11, and the attenuation estimator 15 inputs a channel attenuation amount, that is, Estimate There are various channel estimation methods. In the case of TDD transmission method, there is a method of estimating channel attenuation based on the strength of data received. In the case of non-TDD transmission method, a call channel or an additional channel is received at the receiving end. There is also a method of transmitting the channel state to the transmitter through the transmitter to estimate the amount of channel attenuation. In addition, the channel attenuation amount can be estimated in more various ways.
    [55] The attenuation estimator 15 estimates the estimated channel attenuation Is provided to the control amount determiner 16, the control amount determiner 16 is estimated Estimated by comparing the control tables with The coded section, the modulation level, and the transmit power strength of the corresponding section are found, and the encoder 12, the modulator 13, and the power controller 14 are operated according to the determined control amount.
    [56] The encoder 12 encodes the data stored in the buffer 11 according to the code rate R k under the control of the control amount determiner 16, and the modulator 13 modulates the encoded data according to the modulation level M k .
    [57] As such, after the data is coded and modulated at a coding rate and modulation level capable of obtaining maximum bandwidth efficiency according to the channel attenuation amount, the power controller 14 transmits power that can satisfy the BER required for communication even at the current channel attenuation amount. The power of the raw data is controlled and then provided to the channel and the additional system 20 to be transmitted to the receiving device 20.
    [58] Therefore, high-speed data transmission is achieved with low power while satisfying the BER required in the communication channel where attenuation occurs.
    [59] 4 illustrates an operation sequence of a receiving end in the adaptive transmission method according to the embodiment of the present invention.
    [60] The demodulation / decoding controller 34 of the signal receiving receiver 30 transmitted from the transmission apparatus 10 estimates the code rate and modulation level used by the transmission apparatus 10, and according to the estimated result, the demodulator 31 and The decoder 32 is operated. Here, the transmitting end transmits a code rate, modulation level information or control signal to a transmission signal through a communication channel or an additional channel, and the demodulation / decoding controller of the receiving end estimates the code rate and modulation level of the signal based on this data. In addition, it is possible to estimate the code rate and modulation level of the signal transmitted by more various methods.
    [61] The demodulation / decoding controller 34 of the reception device 30 that receives the signal transmitted from the transmission device 10 uses the code rate and modulation level used by the transmission device 10 based on the control information included in the received signal. The demodulator 31 and the decoder 32 are operated in accordance with the estimated result.
    [62] First, the demodulator 31 demodulates the received data according to the control of the controller 34 according to the estimated modulation level (S202), and then the decoder 32 decodes the demodulated data according to the estimated code rate. (S203). The decoded data is stored in the buffer 33 (S204), and then processed and output or displayed as audio, text or video signals, respectively.
    [63] Although the present invention has been described with reference to the most practical and preferred embodiments, the present invention is not limited to the above disclosed embodiments, but also includes various modifications and equivalents within the scope of the following claims.
    [64] As described above, according to the embodiment of the present invention, it is possible to perform high-speed data transmission with low power while satisfying the BER required in the radio channel with attenuation.
    权利要求:
    Claims (6)
    [1" claim-type="Currently amended] Estimating channel attenuation information of the wireless communication channel;
    Setting a code rate, modulation level, and transmission power of a signal to be transmitted based on the estimated channel attenuation information;
    Encoding a signal according to the set code rate;
    Modulating a signal according to the set modulation level; And
    Transmitting a coded and modulated signal according to the transmission power set above
    Adaptive signal transmission method in a wireless communication system comprising a.
    [2" claim-type="Currently amended] The method of claim 1,
    The setting step
    Combination of Multiple Code Rates and Modulation Levels in and Channel attenuation information when And the threshold that determines the combination of transmission parameters (code rate, modulation level) Estimated channel attenuation information end In this case, the signal is transmitted using (R i (k) , M j (k) ), and the average bandwidth efficiency [R / B] at this time satisfies the following conditions. Adaptive signal transmission method in a wireless communication system.

    ,
    SNR k : Destination received SNR value when (R i (k) , M j (k) ) is used
    : Rayleigh probability density function
    [3" claim-type="Currently amended] The method of claim 2,
    The setting step
    The transmit power that varies according to the channel attenuation information is P ( ), The transmission power P ( ) Satisfies the destination reception SNR k An adaptive signal transmission method in a wireless communication system, characterized in that the following conditions are set.

    ,
    G: Channel gain in Rayleigh channel
    N 0 B: Noise Average Power
    [4" claim-type="Currently amended] The method according to claim 2 or 3,
    Thresholds That Determine Transmission Parameters this

    Conditions are met, where 1 is an adaptive signal transmission method in a wireless communication system, characterized by following conditions.

    [5" claim-type="Currently amended] An attenuation estimator estimating an amount of channel attenuation of the wireless communication channel;
    A control amount determiner for setting a code rate, modulation level, and transmission power of a signal to be transmitted based on the estimated channel attenuation amount;
    An encoder for encoding a signal according to the set code rate;
    A modulator for modulating a signal according to the set modulation level;
    A power controller for transmitting a coded and modulated signal according to the set transmission power
    Adaptive signal transmission apparatus in a wireless communication system comprising a.
    [6" claim-type="Currently amended] The method of claim 5,
    The control amount setter,
    Combination of Multiple Code Rates and Modulation Levels in and Channel attenuation information when And the threshold that determines the combination of transmission parameters (code rate, modulation level) Estimated channel attenuation information end In this case, the signal is transmitted using (R i (k) , M j (k) ), and the average bandwidth efficiency [R / B] at this time satisfies the following conditions. Adaptive signal transmission apparatus in a wireless communication system.

    ,
    SNR k : Destination received SNR value when (R i (k) , M j (k) ) is used
    : Rayleigh probability density function
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    同族专利:
    公开号 | 公开日
    KR100418196B1|2004-02-11|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2001-08-10|Application filed by 한국전자통신연구원
    2001-08-10|Priority to KR10-2001-0048180A
    2003-05-09|Publication of KR20030034262A
    2004-02-11|Application granted
    2004-02-11|Publication of KR100418196B1
    优先权:
    申请号 | 申请日 | 专利标题
    KR10-2001-0048180A|KR100418196B1|2001-08-10|2001-08-10|Adaptive transmission method in wireless communication system and device thereof|
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