201039587 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種OFDM接收器’尤其是一種副載波不需重 排序的OFDM接收器及OFDM信號處理方法。 【先前技術】 正交頻分復用(Orthogonal Frequency Division Multiplexing， p OFDM)是一種把單一資訊分割成複數個副載波(sub-carrier)並且 為了儘量減少分割後副載波之間的間隔而賦予正交性(orthogonal) 並加以復用(multiplex)後傳輸的多載波(Multi-carrier)傳輸技術。 OFDM可以有效地解決寬帶通信的衰減(fading)問題，可以有效地 利用頻率資源，還可以銜接 MIMCXMultiple Input Multiple Output) 之類的技術，將在第四代通信中獲得廣泛的應用。OFDM可以在 單一載波環境中視為難題的山頂或大樓反射電波所造成多路徑干 涉等問題下依然進行高速通信。 Ο 一般來說’ OFDM發送器可以把需要發送的信號從調幅 (modulation)頻率領域(frequency domain)信號轉換成時間領域(time domain)信號後發送，接收器則把所接收的時間領域信號重新轉換 成頻率領域信號後進行處理。時間領域的信號通過快速傅立葉轉 換(Fast Fourier Transform，FFT)轉換成頻率領域的信號，頻率領域 的信號則通過逆快速傅立葉轉換(Inverse Fast Fourier Transform)後 轉換成時間領域的信號。 第1圖係OFDM發送器與接收器的信號收發流程。 3 201039587 請參閱第1圖’發送器110首先把需要發送的信號加以調幅 後形成調幅頻譜信號111。信號調幅可以採取BPSK(Binary Phase Shift Keying)' QPSK(Quadrature Phase Shift Keying) > 16-QAM(Quadrature Amplitude Modulation)及 32-QAM 方式。調幅 頻譜信號111包括了具備調幅資訊的部分(0〜(N-丨))和不具備調幅 資訊的部分(斜線部分)。調幅頻譜信號lu被排序(〇rdering)成排序 頻譜信號112後經過逆快速傅立葉轉換U3(lnverse Fast Fourier Transform)再發送。排序頻譜信號112使内部頻譜信號旋轉 (rotation)—定量後移動到位於調幅頻譜信號lu下側不具備調幅 資訊的部分(斜線部分)中央部位。 接收器120對於所接受的時間領域信號進行快速傅立葉轉換 ffast Fourier Transform)後轉換成頻率領域信號丨23。轉換後的信號 122對應於發送器no的排序頻譜信號112。在後續的處理過程中 ’利用轉換後的信號122進行頻道估測(Channelestimation)以及隨 着頻道估測而來的頻道補償作業，此時需要把轉換後的信號122 重新排序(reordering)成和發送器11〇的調幅頻譜信號丨丨丨形態相同 的頻譜信號121。 OFDM接收器120進行重排序時可以使用下列方式：轉換後 的信號122儲存到記憶體(mem0Iy)里後再重新排序成調幅信號 121、或者重新計算副載波指數(她carrier index)。然而上述方气 需要針對重排序作業而準備額外的記憶體，而且還需要另外準^ 執行重排序作業的電路或者生成控制信號，導致接收器12〇複雜 201039587 化並增加所佔用的資源(resource)。 【發明内容】 本發明需要解決的技術課題是提供一種副載波不需重排序的 OFDM接收器。 本發明需要解決的另一個技術課題是提供一種副載波不需重 排序的OFDM信號處理方法。 為了解決所述技術課題，本發明的接收器包括：j/q解調器、 〇 FFT處理器、小數倍頻偏糾正單元、第一乘法器、整數倍頻偏糾 正單元、第一加法器及第二加法器。 所述I/Q解調器利用OFDM數位信號對I(In phase)信號及和所 述I信號形成90。相位差的Q(quadrature)信號進行解調。所述第一 乘法器將所述I信號與所述Q信號及所述第一加法器的輪出相乘 。所述FFT處理器則針對所述第一乘法器所輸出的信號進行高速 傅利葉演算後產生頻譜信號。所述小數倍頻偏糾正單元輪出的小 〇 數倍賴鍵值可以把所述第_乘法騎輸㈣信射包含的小 數倍頻偏加以抵消。所述整數倍頻偏糾正單元輸出的整數倍頻偏 補償值可以把所述FFT處理器所輸出的頻譜信號令包含的整數倍 頻偏加以抵消。所述第一加法器把所述小數倍頻偏補償值及所述 第二加法器的輸出相加。所述第二加法器把所述整數倍頻偏補償 值及施加到所述I信號與所述q信號上的偏移值M相加。 解決所述另一個技術課題的本發明〇FDM信號處理方法，是 種把所接收的OFDM信號賴成I/Q信號後進行快速傅立葉轉 201039587 括了物：糊挪，把收到的 〇聰信號解調㈣信號;偏移步驟，對所述i/q信號賦予偏移； 以及頻谱域生成步驟，對於經過了所述偏移的叫信號進行快速 傅立葉轉換後生成頻譜信號。 本發明的接收器及信號處理方法在處理所收到的〇腦信號 時不必在副載波FFT進行重排序，因此可以簡化系統並儘量減 少資源使用量。 為了讓本發明之所述目的、特徵、和優點能更明顯，下文配 合所附圖示與較佳實施例作詳細說明如下。 【實施方式】 第2圖係本發明一較佳實施例的副載波不需重排序的〇FDM接 收器的方塊圖。 請參閱第2圖，所述OFDM接收器200包括：ADC210、I/Q 解調器220、FFT處理器230、小數倍頻偏糾正單元240、第一乘 法器]VO、整數倍頻偏糾正單元250、第一加法器A1、第二加法 器A2、符號延遲部260、第二乘法器M2、頻道估測部270及等 化器280。 ADC210可以把OFDM多天線所收到的類比信號轉換後生成所 述OFDM數位信號。I/Q解調器220則利用OFDM數位信號對I(ln phase)信號及和所述I信號形成90〇相位差的Q(quadrature)信號進 行解調。 第一乘法器Ml將I信號與Q信號及第一加法器A1的輸出加 201039587 以相乘。FFT處理器230則針對第一乘法器奶戶斤輪出的信號進 行高速傅_演魏產生賴錄。小餘軸批單元撕輸 出的小數倍頻偏補償值ER1可以把所述第一乘法器奶所輸出的 信號中包含的樣倍雜滅_。整數_綱正單元25〇輸 出的整數倍頻偏補健ER2可以把FFT處理器23〇所輸出的頻譜 信號中包含的整數倍頻偏加以抵消。第一加法器Αι把小數倍頻偏 Ο201039587 VI. Description of the Invention: [Technical Field] The present invention relates to an OFDM receiver', particularly an OFDM receiver and an OFDM signal processing method in which subcarriers do not need to be reordered. [Prior Art] Orthogonal Frequency Division Multiplexing (p OFDM) is a method of dividing a single information into a plurality of sub-carriers and giving positive to minimize the interval between sub-carriers after division. Multi-carrier transmission technology that is orthogonal and multiplexed. OFDM can effectively solve the fading problem of broadband communication, can effectively utilize frequency resources, and can also be connected to technologies such as MIMCX Multiple Input Multiple Output), and will be widely used in the fourth generation communication. OFDM can still perform high-speed communication under the problem of multipath interference caused by a mountaintop or building reflected wave in a single carrier environment. Ο Generally, the OFDM transmitter can transmit the signal to be transmitted from the modulation frequency domain signal to the time domain signal, and the receiver re-converts the received time domain signal. Processing is performed after the frequency domain signal is generated. The signal in the time domain is converted into a signal in the frequency domain by a Fast Fourier Transform (FFT), and the signal in the frequency domain is converted into a signal in the time domain by an Inverse Fast Fourier Transform. Figure 1 shows the signal transmission and reception process of the OFDM transmitter and receiver. 3 201039587 Please refer to FIG. 1 'Transmitter 110 first amplitude-modulates the signal to be transmitted to form amplitude-modulated spectrum signal 111. The signal amplitude modulation can be performed by BPSK (Binary Phase Shift Keying) 'QPSK (Quadrature Phase Shift Keying) > 16-QAM (Quadrature Amplitude Modulation) and 32-QAM. The amplitude modulation spectrum signal 111 includes a portion (0 to (N-丨)) having amplitude modulation information and a portion (hatched portion) having no amplitude modulation information. The amplitude modulated spectrum signal lu is sorted (〇rdering) into a sorted spectrum signal 112 and then transmitted through an inverse fast Fourier transform U3 (lnverse Fast Fourier Transform). The sorted spectral signal 112 rotates the internal spectral signal - quantitatively and then moves to the central portion of the portion (slashed portion) that does not have amplitude modulation information on the lower side of the amplitude modulated spectral signal lu. The receiver 120 performs fast Fourier Transform (ffast Fourier Transform) on the received time domain signal and converts it into a frequency domain signal 丨23. The converted signal 122 corresponds to the ordered spectral signal 112 of the transmitter no. In the subsequent processing, 'channel estimation using the converted signal 122 and the channel compensation operation with the channel estimation, the converted signal 122 needs to be reordered into and sent at this time. The amplitude modulated spectrum signal of the device 11 is the same spectral signal 121 of the same shape. The OFDM receiver 120 may use the following methods for reordering: the converted signal 122 is stored in the memory (mem0Iy) and then reordered into the amplitude modulated signal 121, or the carrier index is recalculated. However, the above-mentioned party needs to prepare additional memory for the reordering operation, and also needs to separately perform the circuit of the reordering operation or generate the control signal, which causes the receiver 12 to be complicated and increase the occupied resources. . SUMMARY OF THE INVENTION The technical problem to be solved by the present invention is to provide an OFDM receiver in which subcarriers do not need to be reordered. Another technical problem to be solved by the present invention is to provide an OFDM signal processing method in which subcarriers do not need to be reordered. In order to solve the technical problem, the receiver of the present invention comprises: a j/q demodulator, a 〇 FFT processor, a fractional multiple frequency offset correction unit, a first multiplier, an integer multiple frequency offset correction unit, and a first adder. And a second adder. The I/Q demodulator forms 90 with an I (In phase) signal and with the I signal using an OFDM digital signal. The phase difference Q (quadrature) signal is demodulated. The first multiplier multiplies the I signal by the Q signal and the round of the first adder. The FFT processor then generates a spectral signal after performing high speed Fourier calculus on the signal output by the first multiplier. The fractional multiplication key value of the fractional octave correction unit may offset the fractional octave included in the _th multiplication riding (four) signal. The integer multiple frequency offset compensation value output by the integer multiple frequency offset correction unit may offset the integer frequency doubling of the included spectral signal output by the FFT processor. The first adder adds the fractional multiple offset compensation value and the output of the second adder. The second adder adds the integer double frequency offset compensation value and an offset value M applied to the IQ signal to the q signal. The 〇FDM signal processing method of the present invention which solves the other technical problem is to convert the received OFDM signal into an I/Q signal and then perform a fast Fourier transform 201039587. The object is: the paste is moved, and the received signal is received. Demodulating (four) signals; an offset step of assigning an offset to the i/q signal; and a spectral domain generating step of generating a spectral signal after performing fast Fourier transform on the signal subjected to the offset. The receiver and signal processing method of the present invention does not have to be reordered in the subcarrier FFT when processing the received camphor signal, thereby simplifying the system and minimizing resource usage. The above described objects, features, and advantages of the invention will be apparent from the accompanying drawings. [Embodiment] FIG. 2 is a block diagram of a 〇FDM receiver in which subcarriers do not need to be reordered according to a preferred embodiment of the present invention. Referring to FIG. 2, the OFDM receiver 200 includes: an ADC 210, an I/Q demodulator 220, an FFT processor 230, a fractional multiple offset correction unit 240, a first multiplier VO, and an integer multiple frequency offset correction. The unit 250, the first adder A1, the second adder A2, the symbol delay unit 260, the second multiplier M2, the channel estimation unit 270, and the equalizer 280. The ADC 210 can convert the analog signal received by the OFDM multi-antenna to generate the OFDM digital signal. The I/Q demodulator 220 demodulates the I (ln phase) signal and the Q (quadrature) signal which forms a 90 〇 phase difference with the I signal using an OFDM digital signal. The first multiplier M1 multiplies the I signal and the Q signal and the output of the first adder A1 by 201039587. The FFT processor 230 performs a high-speed _ _ wei on the signal of the first multiplier milker. The fractional multiple offset compensation value ER1 of the small residual shaft batch unit can output the sample contained in the signal output by the first multiplier milk. The integer octave unit 25 〇 output integer multiple octave offset ER2 can offset the integer octave bias contained in the spectrum signal output by the FFT processor 23 。. The first adder Αι biases the fractional octave
補償值ER1及第二加法器A2的輸出相加。第二加法器齡所述 整數倍頻偏補償值ER2及施加到所述ϊ信號與所述Q信號上的偏 移值Μ相加. ° ~ 符號延遲部260可以把構成FFT處理器23〇所輸出頻譜信號的 符號加以延遲。頻道估測部27()利用FFT處理器23G所輸出的頻 譜信號對頻道進行估測後輸出頻道補償信號。帛二乘法器…把 2號延遲部260的輸出信號及頻道估測部27()的輸出信號加以相 等化器280對第一乘法器M2的輸出進行等化(叫⑽脇祕理 〇 第3圖定義了第2圖所示偏移值M。 請參閱第3圖，對應於頻譜信號(第1圖的出，m)，按昭具備 =資訊的-部分區域A、不具備調幅資訊的部分(斜線)及。調 2訊的錄部Μ _序__時，仰使鱗健旋轉， :值_旋轉量滅於具備調_觸-部分關Α及不具備 調幅資訊的部分(斜線)之和。 其匕符號延遲部26〇、頻道估測部WO及等化器MO的動作屬 201039587 於已知内容，此處不予詳細說明。 下面是憑藉第2圖所示接收器對i/q信號偏移的補償作用而不 再需要在FFT之後進行重排序的數學解釋。 OFDM信號藉着對正交性載波進行調幅後形成，使用了由所輸 入的位元流(bit stream)映射(mapping)到作為複數符號(c〇mplex symbol)的I/Q符號後生成的符號序列(seqUence)。透過該過程減少 了位元流的OFDM信號可以由數學式1表示。 【數學式1】 W~m, J7=0 w-w=：ei-% 此時，N表示副載波(sub-carrier)數量，x[m]表示[〇，N-1]區段 的第m個符號。 假設數學式1所示副載波在頻率領域調變(shift)的量’調變後 的副載波可以由數學式2表示。 【數學式2】The outputs of the compensation value ER1 and the second adder A2 are added. The second adder ages the integer multiple frequency offset compensation value ER2 and the offset value Μ applied to the chirp signal and the Q signal. The symbol delay unit 260 can constitute the FFT processor 23 The sign of the output spectrum signal is delayed. The channel estimation unit 27() estimates the channel by using the spectrum signal output from the FFT processor 23G, and outputs a channel compensation signal. The second multiplier ... equalizes the output signal of the delay unit 260 and the output signal of the channel estimation unit 27 () to the equalizer 280 to equalize the output of the first multiplier M2 (called (10) The figure defines the offset value M shown in Fig. 2. Please refer to Fig. 3, corresponding to the spectrum signal (outlet in Fig. 1, m), according to the section with the information = part of the area A, the part without the amplitude modulation information (slash) and the recording part of the 2 signal _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ The operation of the 匕 symbol delay unit 26〇, the channel estimation unit WO, and the equalizer MO is known from 201039587 and will not be described in detail herein. The following is the receiver pair i/q shown in Fig. 2. The compensation of the signal offset eliminates the need for a mathematical interpretation of the reordering after the FFT. The OFDM signal is formed by amplitude modulation on the orthogonality carrier, using mapping of the input bit stream (mapping) a sequence of symbols (seqUence) generated after the I/Q symbol as a complex symbol (c〇mplex symbol). The OFDM signal with less bit stream can be expressed by Mathematical Formula 1. [Math 1] W~m, J7=0 ww=:ei-% At this time, N represents the number of sub-carriers, x[m ] represents the mth symbol of the [〇, N-1] section. It is assumed that the subcarrier of the subcarrier shown in Mathematical Formula 1 is shifted in the frequency domain. The subcarrier after modulation can be expressed by Math. Mathematical formula 2]
Jt_ Q 請參閱數學式2，在頻率領域調變了 M量的副載波可以透過 和時間領域中具備M/N頻率的正弦波相乘後得到。請參閱第2圖 ，本發明提供的副載波不需重排序的OFDM接收器憑藉對I信號 及Q信號賦予的偏移Μ而實現頻譜信號的旋轉處理。 先前的OFDM接收器僅對I/q信號給予一定量的頻偏後進行 FFT，然後針對FFT後的信號進行重排序過程。請參閱第2圖， 201039587Jt_ Q Please refer to Mathematical Formula 2. The subcarriers that have been modulated in the frequency domain by M can be obtained by multiplying the sine wave with M/N frequency in the time domain. Referring to FIG. 2, the OFDM receiver provided with the subcarriers without reordering according to the present invention realizes the rotation processing of the spectrum signal by virtue of the offset 赋予 given to the I signal and the Q signal. The previous OFDM receiver performs FFT only after giving a certain amount of frequency offset to the I/q signal, and then performs a reordering process on the FFT signal. Please refer to Figure 2, 201039587
本發明則如第2圖所示對FFT之前的信號賦予偏移而不必在FFT 完畢後進行重排序或者儘量減少重排序塊(block)。 前文僅對接收器做了詳細說明，但接收器所執行的過程可以 如下類推。即接收器的〇FDM信號處理方法採取的是把所接收的 OFDM信號解調成I/Q信號後進行快速傅立葉轉換的〇fdm信號 處理方法’其包括：解調步驟，把所接收的OFDM信號解調成I/(j 信號；偏移步驟’對所述i/Q信號賦予偏移；以及頻譜信號生成步 驟’對於經過了所述偏移的!/Q信號進行快速傅立葉轉換後生成頻 譜信號。 、/前文係觸本剌之雛實_和賦為本剌之技術特徵 進行具體之說明，但所述較佳實施並不能限定本發明之範圍。熟 悉此項技術之人士當可在不脫離本發明之精神與原則下對本發明' 進行變更與修改，而該等變更與修改，皆應涵蓋於如下申請專利 範圍所界定之範疇中。 Q 【圖式簡單說明】 第1圖係OFDM發送器與接收器的信號收發流程。 第2圖係本發明一較佳實施例的副載波不需重排序的接收 器方塊圖。 第3圖定義了第2圖所示偏移值Μ。 【主要元件符號說明】 發送器 110 調幅頻譜信號 ill 9 201039587 排序頻譜信號 112 逆快速傅立葉轉換 113 接收器 120 頻譜信號 121 轉換後的信號 122 頻率領域信號 123 OFDM接收器 200 ADC 210 I/Q解調器 220 FFT處理器 230 小數倍頻偏糾正單元 240 整數倍頻偏糾正單元 250 符號延遲部 260 頻道估測部 270 等化器 280 偏移值 Μ 第一乘法器 Ml 第二乘法器 M2 第一加法器 A1 第二加法器 A2The present invention assigns an offset to the signal before the FFT as shown in Fig. 2 without having to reorder after the FFT is completed or to minimize the reorder block. The receiver has only been described in detail above, but the process performed by the receiver can be analogized as follows. That is, the 〇FDM signal processing method of the receiver adopts a 〇fdm signal processing method for performing fast Fourier transform after demodulating the received OFDM signal into an I/Q signal, which includes: a demodulation step, and the received OFDM signal Demodulating into an I/(j signal; an offset step 'to assign an offset to the i/Q signal; and a spectral signal generating step' to perform a fast Fourier transform on the !/Q signal subjected to the offset to generate a spectral signal The prior art is described in detail with reference to the technical features of the present invention, but the preferred embodiment does not limit the scope of the present invention. Those skilled in the art can The present invention is subject to changes and modifications of the present invention, and such changes and modifications are intended to be included within the scope of the following claims. Q [Simple Description] Figure 1 is an OFDM transmitter. The signal transmission and reception process with the receiver. Fig. 2 is a block diagram of the receiver in which the subcarriers do not need to be reordered according to a preferred embodiment of the present invention. Fig. 3 defines the offset value 第 shown in Fig. 2. Symbolic Transmitter 110 Amplitude Spectrum Signal ill 9 201039587 Sort Spectrum Signal 112 Inverse Fast Fourier Transform 113 Receiver 120 Spectrum Signal 121 Converted Signal 122 Frequency Domain Signal 123 OFDM Receiver 200 ADC 210 I/Q Demodulator 220 FFT Processing Counter 230 fractional frequency offset correction unit 240 integer multiple frequency offset correction unit 250 symbol delay unit 260 channel estimation unit 270 equalizer 280 offset value Μ first multiplier M1 second multiplier M2 first adder A1 Two adder A2