1260879 九、發明說明： ' 【發明所屬之技術領域】 本發明係關於一種採用OFDM傳送裝置以及0Fdm接 收衣置’尤指一種適用於採用η階相位差調變之〇fdm傳送 放置以及採用n階相位差解調變之〇FDm接收裝置。 【先前技術】 二 在無線通信系統中，多載波系統較單一載波系統具有 許多明顯之優點，其將資料分別藉由不同之子載波以進行 _ 10貝料之傳送。為確保資料之正確性，每一子載波之間需存 在保護頻帶（guard band )，以防止子載波彼此間的干擾。 然而，為了充份利用頻寬之資源並確保資料之正確性，使 · 用者將複數子載波彼此相互正交，如此一來，即可降低子 · 載波彼此相互干擾之現象，此方法稱為正交分頻多工 15 ( 〇rth〇g〇nal Frequency Division Multiplexing，〇fdm )。 依據貫驗之數據，〇FDM系統約可節省5〇%之頻寬。 如圖1所示，傳統0FDM傳送裝置包括下列元件： 馨 編碼器12，係用以輸入數位資料並對其進行錯誤更正 編碼處理，以輸出編碼訊號，如此一來，可強化錯誤更正 20 之能力。 ' 傳統調變器14，係用以輸入編碼訊號並對其進行調變 處理，以輸出調變訊號，其中，調變技術可為二元相移鍵 控调變（Binary Phase Shift Keying，BpSK )、正交相移鍵 5 1260879 控調變（Quadrature Phase Shift Keying，QPSK )、或正交 振幅調變（Quadrature Amplitude Modulation，QAM )。 序列/平行普換器1 6，係用以輸入調變訊號並對其進行 序列/平行轉換處理，以輸出複數平行調變訊號，其中，平 5 行調變訊號之數目等於子載波之數目。 IFFT ( Inverse Fast Fouries Transformer，IFFT)器 18， 係用以輸入複數平行調變訊號並對其進行IFFT處理，以輸 出複數平行IFFT訊號。 平行/序列轉換器20，係用以輸入複數平行IFFT訊號並 ίο對其進行平行/序列轉換處理，以輸出序列IFFT訊號。 循環岫置碼器22，係用以輸入序列IFFT訊號並對其加 入循％子首（cyclic prefix)，以輸出循環聊丁訊號。 數位 /類比轉換器（Digital/Analog Converter，DAC ) 24,係用以輸入循環„^了訊號並對其進行數位/類比轉換處 5 〇以輸出無線通訊信號，再藉由天線而將此無線通訊信 \傳。至遠立而之〇FDM接收裝置，如圖2所示。由於QFDM 接收衣置之運作與係為傳統〇1?£)]^傳送裝置之運作係為反 向運作，使用者可自行類推，故不多作說明。 而，當OFDM接收裝置移動時，無線通訊信號將產 勒位移（D〇ppler shift)，因而降低〇FD]y^|^收裝置 所接^之無線通訊信號之準確率。此外，〇FDM接收裝置 =可此因為本地振盪器所輸出之頻率非理想化，因而使子 服間?失正交性，導致無法解讀無線通訊信號。為克 述問題，使用者需要一種具有頻率位移低敏感性之 1260879 OFDM傳送裝置 【發明内容】 本發明OFDM傳送裝置係採用n階相位差調變以作為 訊號調變之方法，並由本發明〇FDM接收裝置執行係η階相 位差解調變，η為大於!之正整數，較佳為2,故能克服傳統 〇FDM傳送裝置或傳統OFDM接收裝置之缺失。 10 15 本發明OFDM傳送裝置包括下列元件：編碼号，係用 以，入數位資料並對其進行錯誤更正編碼處理以輸出編碼 相位差調變器’係用以輸人編碼訊號並對盆進行 η階差分相移鍵控調變處理以輸出調變訊號；序列/平行轉 換器’係用以輸入調變訊號並對其進行序列 以輸㈣數平行調變訊號；反快速富利葉轉換器轉:用^ 輸入複數平H變訊號絲其進行iff 出 付™H行/序麵器，係用以輸 =訊其進行平行/序列轉換處理，以輸出一 二’係用以輸入序列1FFT訊號並對其加 伟用时入节環IFFT訊號；以及數位/類比轉換器， ===附訊號觸其⑽㈣比轉換處 傳送至遠端。H虎’再精由天線而將無線通訊信號 器，係藉由天：:二收：置包括下列元件··數位/類比轉換 轉換處理以輸㈣=5通/=號’並其進行類比/數位 衣FFTafl號，循環前置碼移除器，係用 20 1260879 ίο 15 …序列/平行轉換器，係用以輸入序列ι™號， σ" •、八進仃序列/平仃轉換處理，以輸出複數平行肿丁訊 號；快速富利葉轉換器，係用以輸入該等平行赠訊號並 對，進行FFT處理以輸出複數平行調變訊號；平行/序列轉 換為’係肖以輸人複數平行調變訊號並對其進行平行/序列 轉換處理以輸出調變訊號；η階相位差解調變器，係用以輸 入凋文吼唬並對其進行η階差分相移鍵控解調變處理以輸 /出編碼訊號，·以及解碼器，係用以輸入編碼訊號並對其進 行錯5吳更正解碼處理以輸出數位資料。其中，η為大於1之 正整數，較佳為2，即本發明〇FDM傳送裝置較佳採用 D PSK以作為訊號調變之方法，並由本發明〇fdm接收裝 置執行相對應d2psk之解調變，由於D2PSK調變配合d2psk 解凋麦而使無線通訊信號具有頻率位移低敏感性之特性， 故此克服使用BPSK、QPSK、或QAM之傳統OFDM傳送裝 置或接收裝置之缺失。 【實施方式】 為能讓貴審查委員能更瞭解本發明之技術内容，特 20舉一較佳具體實施例說明如下。 差分相移鍵控調變又稱為一階相位差分（First_〇rder Phase Difference ’ FOPD )調變，可應用在載波恢復（carrier recovery )為困難之無線通信系統，或接收裝置需精簡化 之無線通信系統。然而，使用差分相移鍵控調變之傳統 1260879 OFDM傳送裝署目士 · 1具有頻率位移高敏感性之缺失。因此’如 圖3所不’在；^银价 ^ m &例中，本發明OFDM傳送裝置係採用執 一2 、’刀相矛夕鍵控調變（Double differential PSK， D PSK )之调變器3〇，以對編碼訊號進行調變處理，以輸 5出可克服頻率偏移效應之調變訊號。其中，D2psK又稱作 第二階相位矣f Q 1 在 V Second-Order Phase Difference，SOPD)調 艾其特欲為儲存二個FOPD之差。由於SOPD如下列方程 式（1 )所示： 「<^各{^ a nm ( 1) · ι〇 &是傳輸在第k個時間區間之訊號的真實相位，m為自 然數’ M及△八-m分別為FOPD，Δ2么即為SOPD。其中，Δ2么之 值將為下述集合之其中之一：1260879 IX. Description of the invention: 'Technical field to which the invention pertains>> The present invention relates to an OFDM transmission device and an OFDM reception device, in particular, a 〇fdm transmission placement suitable for η-order phase difference modulation and using n-order The phase difference demodulation becomes a 〇FDm receiving device. [Prior Art] In the wireless communication system, the multi-carrier system has many obvious advantages over the single carrier system, and the data is transmitted by different sub-carriers respectively. To ensure the correctness of the data, a guard band is required between each subcarrier to prevent interference between the subcarriers. However, in order to make full use of the bandwidth resources and ensure the correctness of the data, the user can orthogonalize the plurality of subcarriers to each other, thereby reducing the phenomenon that the subcarriers interfere with each other. This method is called Orthogonal frequency division multiplexing 15 (〇rth〇g〇nal Frequency Division Multiplexing, 〇fdm). Based on the data from the inspection, the FDM system can save about 5% of the bandwidth. As shown in FIG. 1, the conventional OFDM transmission device includes the following components: a singular encoder 12 for inputting digital data and performing error correction coding processing to output an encoded signal, thereby enhancing the ability of error correction 20 . The conventional modulator 14 is used to input a coded signal and perform a modulation process to output a modulated signal. The modulation technique can be Binary Phase Shift Keying (BpSK). , Quadrature Phase Shift Key 5 1260879 Control Phase Shift Keying (QPSK), or Quadrature Amplitude Modulation (QAM). The sequence/parallel converter 16 is used to input the modulation signal and perform sequence/parallel conversion processing to output a plurality of parallel modulation signals, wherein the number of the 5-line modulation signals is equal to the number of sub-carriers. An IFFT (Inverse Fast Fouries Transformer, IFFT) unit 18 is configured to input a complex parallel modulation signal and perform an IFFT processing to output a plurality of parallel IFFT signals. The parallel/sequence converter 20 is configured to input a complex parallel IFFT signal and perform parallel/sequence conversion processing to output a sequence IFFT signal. The cyclic coder 22 is used to input a sequence IFFT signal and add a cyclic prefix to the loop to output a cyclical signal. A digital/analog converter (DAC) 24 is used to input a loop signal and perform a digital/analog conversion at 5 〇 to output a wireless communication signal, and then wirelessly communicate with the antenna. Letter\传. To the far-reaching FDM receiving device, as shown in Figure 2. Since the operation of the QFDM receiving clothing is the same as the operation of the traditional device, the user operates in reverse. It can be analogized by itself, so it is not explained. However, when the OFDM receiving device moves, the wireless communication signal will be shifted (D〇ppler shift), thus reducing the wireless communication of the 〇FD]y^| The accuracy of the signal. In addition, the 〇FDM receiving device=may because the frequency output by the local oscillator is not idealized, so the orthogonality between the sub-services is lost, and the wireless communication signal cannot be interpreted. There is a need for a 1260879 OFDM transmission device with low frequency sensitivity. [Inventive] The OFDM transmission device of the present invention employs n-th order phase difference modulation as a method of signal modulation, and is implemented by the 〇FDM receiving apparatus of the present invention. The phase difference is demodulated, and η is a positive integer greater than !, preferably 2, so that the absence of the conventional 〇FDM transmission device or the conventional OFDM reception device can be overcome. 10 15 The OFDM transmission device of the present invention includes the following components: code number, For inputting digital data and performing error correction coding processing to output a coded phase difference modulator for inputting a coded signal and performing an n-step differential phase shift keying modulation process on the basin to output a modulation signal; The serial/parallel converter is used to input the modulation signal and sequence it to input the (four) number of parallel modulation signals; the inverse fast Fourier converter: use ^ to input the complex flat H signal to perform the iff payment TMH line/sequencer is used to input parallel/sequence conversion processing to output one or two 'systems for inputting sequence 1 FFT signals and adding them to the ring-shaped IFFT signal; and digital/analog The converter, === the signal is touched (10) (four) is transmitted to the far end than the conversion. The H tiger 'refines the wireless communication signal by the antenna, by the day:: two: the following components · · digits / Analog conversion conversion processing to lose (four) = 5 /=#' and its analog/digital FFTafl number, cyclic preamble remover, with 20 1260879 ίο 15 ... sequence / parallel converter, used to enter the sequence ιTM number, σ " •, eight into仃 sequence/quad conversion processing to output a plurality of parallel swollen signals; a fast Fourier converter for inputting the parallel novo signals and performing FFT processing to output complex parallel modulation signals; parallel/sequence conversion In order to 'transform the parallel variable modulation signal and perform parallel/sequence conversion processing to output the modulation signal; the n-th order phase difference demodulation transformer is used to input the deduction file and perform the n-order The differential phase shift keying demodulation process is to input/output the encoded signal, and the decoder is used to input the encoded signal and perform a decoding process to output digital data. Where η is a positive integer greater than 1, preferably 2, that is, the 〇FDM transmission device of the present invention preferably adopts D PSK as a signal modulation method, and performs demodulation of the corresponding d2psk by the 〇fdm receiving device of the present invention. Because the D2PSK modulation combined with the d2psk solution, the wireless communication signal has the characteristics of low frequency displacement sensitivity, thus overcoming the lack of the conventional OFDM transmission device or receiving device using BPSK, QPSK, or QAM. [Embodiment] In order to enable the reviewing committee to better understand the technical contents of the present invention, a preferred embodiment will be described below. Differential phase shift keying modulation, also known as First_〇rder Phase Difference 'FOPD' modulation, can be applied to wireless communication systems where carrier recovery is difficult, or the receiving device needs to be simplified. Wireless communication system. However, the traditional 1260879 OFDM transmission setup using differential phase shift keying modulation has a high frequency displacement sensitivity. Therefore, the 'OFDM transmission device of the present invention adopts the adjustment of the double differential PSK (D PSK) in the example of the silver price ^ m & The transformer 3〇 is used to modulate the encoded signal to output a modulated signal that overcomes the frequency offset effect. Among them, D2psK is also called second-order phase 矣f Q 1 in V Second-Order Phase Difference (SOPD). It is intended to store the difference between two FOPDs. Since the SOPD is as shown in the following equation (1): "<^ each {^ a nm ( 1) · ι〇& is the true phase of the signal transmitted in the kth time interval, m is the natural number 'M and △ Eight-m is FOPD, and Δ2 is SOPD. The value of Δ2 will be one of the following sets:
1=0，1，···，Μ-1，並於第k個時間區間中進行資料之傳 15送’此時間區間之時間長度t為^雄+ i)r。當—丨時，F〇pD 表是相鄰時間區間的訊號相位差，此時，s〇pD可表示成方 程式（2) : · △2火=A》k 一 △么丨=(n) 一 (<d) ϋΗ + ι—2 ( 2) 20 因此，D2pSK訊號可以藉由雙重差分編碼器（d〇uble differential encoder) 34 以及 Μ 元相移鍵控（Mary phase Shift Keying，MPSK)調變器36而獲得，如圖4所示。因此， 本發明OFDM傳送裝置係以調變器3〇以替代傳統調變器 M，使本發明0FDM傳送裝置所輸出之無線通訊信號於接 9 1260879 收端解調時具有頻率位移低敏感 30包括： 性之特性，其中 調變器 序餅賴㈣A係用讀人編碼㈣並對其進行 序列/平行轉換處理’以輸出厘元資料序列（―“ 5 sequence)，而μ為正整數。 '差分編碼器34，係用以輪入Μ元資料序列並對其進行 差分編碼處理，以輸出差分訊號。1=0,1,···,Μ-1, and data transmission in the kth time interval 15 send 'The time length t of this time interval is ^雄+ i)r. When 丨, the F〇pD table is the signal phase difference of adjacent time intervals. At this time, s〇pD can be expressed as equation (2): · △2 fire = A"k △ 丨 丨 = (n) (<d) ϋΗ + ι—2 ( 2) 20 Therefore, the D2pSK signal can be modulated by a dual differential encoder 34 and a phase shift key shift (MPSK). Obtained by the device 36, as shown in FIG. Therefore, the OFDM transmission apparatus of the present invention replaces the conventional modulator M with a modulator 3, so that the wireless communication signal output by the OFDM transmitting apparatus of the present invention has a frequency shift low sensitivity 30 when the terminal 12 1260879 is demodulated. : Sexual characteristics, in which the modulator order is based on (4) A is read by the person code (4) and is subjected to sequence/parallel conversion processing to output the numerogen data sequence ("5 sequence", and μ is a positive integer. 'Differential The encoder 34 is configured to rotate the data sequence of the unit and differentially encode the same to output a differential signal.
Μ元相移鍵控調變器3 6 ’係、用以輸人差分訊號並對並 進行Μ元相移鍵控調變處理，以輸出D4SK調變訊號至序 Η)列砰行轉換器18，再由序列/平行轉換器18對〇2聊調變訊 號進行序列/平行轉換處理，以輸出複數平行調變訊號。由 於序列/平行轉換器32、差分編碼器34、及河元相移鍵控調 變is 36皆為習知元件，故不多作說明。 因此，方程式（2 )可改寫成下列方程式（3 ): 15 Φ], ~ 17^ + Φ/c-i + Φ^ηι ~ Φ],-πι-\ mod 2π ( 3 )The unit phase shift keying modulator 3 6 ' is used to input the differential signal and perform the unit phase shift keying modulation processing to output the D4SK modulation signal to the serial port. Then, the sequence/parallel converter 18 performs sequence/parallel conversion processing on the 〇2 chattitude signal to output a plurality of parallel modulation signals. Since the sequence/parallel converter 32, the differential encoder 34, and the river element phase shift keying modulation is 36 are well-known components, they will not be described. Therefore, equation (2) can be rewritten into the following equation (3): 15 Φ], ~ 17^ + Φ/c-i + Φ^ηι ~ Φ], -πι-\ mod 2π ( 3 )
&為Μ元資料序列，其值等於〇，！，…，。由於八亦可 表示如方程式（4 ): ^k=j^ck , ck=(〇?l5...5M-l) … （4) Q為差分訊號，將方程式.（4 )代入方程式（3 )則可 20得到Μ元資料序列與差分訊號之關係方程式，如方程式（5) 所示：& is a sequence of data, the value is equal to 〇,! ,...,. Since eight can also be expressed as equation (4): ^k=j^ck , ck=(〇?l5...5M-l) ... (4) Q is a differential signal, and equation (4) is substituted into equation (3) ), then 20 can get the relationship equation between the data sequence of the unit and the differential signal, as shown in equation (5):
Ck +ck-l ^ck~m-\ +ck~m mod Λ/ ( 5、 其中，mod表示模數（modu]0 )。因此，差分編碼器 34之示意圖如圖5所示。此外，當^==1時，則調變器3〇又稱 10 1260879 為相鄰雙重差分相移鍵控調變調變器（ad PSK Modulator )。在本實施例中，μ較佳為4，如此一來’ Μ 元資料序列與差分訊號之關係如表一所示： 數值 Μ元資料序列 相位差 cos a2A sin δ2么 0 00 0 + 1 0 1 01 7Γ /2 0 十1 2 10 一 π -1 0 3 11 3 π /2 0 -1 本發明OFDM傳送裝置係採用D2pSK之調 10 當然爾，本發明OFDM接收裝置亦需採用d2PSK之解調變 态40，如圖6所示，如此一來，本發明OFDM接收裝置方能 正確地執行解調變處理以輸出數位資料。由於d2psk之解 調變器之實作方式可依使用者之需求而進行設計，在此， 僅以d2psk之解調變器40進行範例性說明，並不以此為 限^圖7所示’解調變器爾人輸人訊號⑽，並假設輸 入訊號叻)具有頻率偏移Δω以及另一相位成份"，上述二個 非理想參數係模擬非理相盔魄 卜U線通道（ehannel)之傳輸結 ，别入汛號、(〇可表示如方程式（6)所示： rk(t) -Ac〇s[(c〇c + Aa))t ^k^k]ikT,t^ ήτ (6) 15 1260879 其中，％為子載波之頻率，―是子載波所具有之頻率 偏移，么是儲存資訊的相位，％是傳輸在第k個時間區間的 相位成份，則 rk-iQ)= A cos [(〇)c + ΑωΧί - Γ)+ φ^λ + η k^] ( 7) W = ^ (〇 = ^ cos[(^c + - mr )+ + Vk_m ] ( 8) 4)=rM_)Wdcc)S{(% +△_ —(料 1)r]+八(9) 經過乘法法器及帶通濾波器^及^後，帶通濾波器Fi 及F 2分別輸出义(丨）以及卜）： 10Ck +ck-l ^ck~m-\ +ck~m mod Λ / (5, where mod represents the modulus (modu) 0. Therefore, the schematic diagram of the differential encoder 34 is as shown in Fig. 5. In addition, when When ^==1, the modulator 3〇 is also referred to as 10 1260879 as an adjacent double differential phase shift keying modulator (ad PSK Modulator). In this embodiment, μ is preferably 4, thus The relationship between the data sequence and the differential signal is shown in Table 1: Numerical unit data sequence phase difference cos a2A sin δ2 0 00 0 + 1 0 1 01 7Γ /2 0 10 1 2 10 1 π -1 0 3 11 3 π /2 0 -1 The OFDM transmission apparatus of the present invention adopts the adjustment of D2pSK. Of course, the OFDM receiving apparatus of the present invention also needs to adopt the demodulation metamorphosis 40 of d2PSK, as shown in FIG. 6, so that the present invention The OFDM receiving apparatus can correctly perform demodulation processing to output digital data. Since the implementation of the d2psk demodulation transformer can be designed according to the needs of the user, here, only the d2psk demodulator 40 For the exemplary description, it is not limited to this. The demodulator input signal (10) shown in Figure 7 assumes that the input signal 叻 has a frequency offset. ω and another phase component ", the above two non-ideal parameters are analog transmissions of the illuminating junction of the U-line channel (ehannel), with the apostrophe, (〇 can be expressed as shown in equation (6): rk (t) -Ac〇s[(c〇c + Aa))t ^k^k]ikT,t^ ήτ (6) 15 1260879 where % is the frequency of the subcarrier and ― is the frequency offset of the subcarrier Shift, what is the phase of storing information, % is the phase component transmitted in the kth time interval, then rk-iQ)= A cos [(〇)c + ΑωΧί - Γ)+ φ^λ + η k^] ( 7) W = ^ (〇= ^ cos[(^c + - mr )+ + Vk_m ] ( 8) 4)=rM_)Wdcc)S{(% +△_ —(material 1)r]+eight (9 After the multiplier and the bandpass filter ^ and ^, the bandpass filters Fi and F 2 respectively output the meaning (丨) and b): 10
+ A.> - (.c + + 〇Γ + ^ + + ^ + ^ ] 以0=手-‘ + △,> — R +少+ & +》“ +〜切“] 之後，以/)以及八幻經過乘法器及低通濾波器打及料 後，低通濾波器F3及F4分別輸出动)以及Ζ2(ί): i(〇= fees [(4 . ：J^C0S AVk 丨)] 15+ A.> - (.c + + 〇Γ + ^ + + ^ + ^ ] with 0=hand-' + △,> — R + less + & +" "+~cut"] /) and after the eight-magic multiplier and low-pass filter are applied, the low-pass filters F3 and F4 output respectively) and Ζ2(ί): i (〇= fees [(4 . :J^C0S AVk 丨)] 15
由於Zl以及z2並不包括上述非理想參數，相位令 “，故可以得知解調變器40之輸出結果⑽和22(ί) 移“無關。如表一所示，當21輸出>0，Ζ2無輸出時，^ Μ兀貢料序列為00;當21無輸出"2輸 ;㈣列為〇1;當，出一 2無輸出時，則表=; ^ ，當21無輸出"2輸出<G時，則表示Μ元資料月 為Η)。如此-來，解調變器4〇即可輸出 $ 再由解碼器進行解碼處理，以輸出數位資料。 頻率偏移4 Μ時，則解調變器4G皆可正常^㈣ 12 20 1260879 變之運作，亦可稱解調變器40為頻率無變化自相關性解調 器（frequency-invariant auto-correlated demodulator)。 雖然在本實施例中，僅以二階相位差調變進行調變器 30之說明，然而，可想而知地，使用者亦可採用辽階相位差 5調變以實現調變器30，並能更有效地克服頻率偏移的問 通’其中’ η為大於1之正整數，因此，n不以2為限。 由於，本發明OFDM傳送裝置係採用D2PSK以作為訊 號調變之方法，並由本發明0FDM接收裝置執行係D2psK 之解調變，D2PSK調變配合d2PSK解調變而使無線通訊信 ίο號具有頻率位移低敏感性之特性，故能克服使用BPSK、 QPSK、或QAM之傳統0FDM傳送裝置或接收裝置之缺失。 上述實施例僅係為了方便說明而舉例而已，本發明所 主張之權利範圍自應以申請專利範圍所述為準，而非僅限 於上述實施例。 15 【圖式簡單說明】 圖1係傳統OFDM傳送裝置之功能方塊圖。 圖2係傳統0FDM接收裝置之功能方塊圖。 圖3係本發明0FDM傳送裝.置之功能方塊圖。 20 圖4係使用D2pSK之調變器之功能方塊圖。 圖5係差分編碼器之示意圖。 圖6係本發明OFDM接收裝置之功能方塊圖。 圖7係D2PSK解調變器之功能方塊圖。 25【主要元件符號說明】 13 1260879 12 編碼器 14 傳統調變器 16 序歹1J /平行轉換器 18 IFFT 器 20 平行/序列轉換器 22 循環前置碼器 24 數位/類比轉換器 26 數位/類比轉換器 30 調變器 32 序列/平行轉換器 34 差分編碼器 36 Μ元相移鍵控調變器 40 解調變器Since Zl and z2 do not include the above non-ideal parameters, the phase is ", so it can be known that the output (10) and 22 (ί) shift of the demodulator 40 are irrelevant. As shown in Table 1, when 21 outputs > 0, Ζ 2 has no output, ^ Μ兀 tribute sequence is 00; when 21 has no output " 2 lose; (4) is listed as 〇 1; when, when 2 has no output , then table =; ^, when 21 has no output &2; output < G, it means that the data month is Η). In this way, the demodulator 4 can output $ and then the decoder performs decoding processing to output digital data. When the frequency offset is 4 ,, the demodulator 4G can be normal. ^ (4) 12 20 1260879 The operation of the variable, or the demodulator 40 is a frequency-invariant auto-correlated demodulator (frequency-invariant auto-correlated) Demodulator). Although in the present embodiment, the description of the modulator 30 is performed only by the second-order phase difference modulation, it is conceivable that the user can also use the L-order phase difference 5 modulation to implement the modulator 30, and A more efficient way to overcome the frequency offset 'where ' η is a positive integer greater than 1, so n is not limited to 2. Since the OFDM transmission apparatus of the present invention adopts D2PSK as a signal modulation method, and the OFDM receiving apparatus of the present invention performs demodulation of the D2psK, the D2PSK modulation is combined with the d2PSK demodulation to make the wireless communication signal ίο have a frequency shift. The low sensitivity characteristics can overcome the lack of traditional OFDM transmitters or receivers using BPSK, QPSK, or QAM. The above-described embodiments are merely examples for the convenience of the description, and the scope of the claims is intended to be limited by the scope of the claims. 15 [Simplified Schematic] FIG. 1 is a functional block diagram of a conventional OFDM transmission apparatus. 2 is a functional block diagram of a conventional OFDM receiving device. Figure 3 is a functional block diagram of the OFDM transmission device of the present invention. 20 Figure 4 is a functional block diagram of a modulator using D2pSK. Figure 5 is a schematic diagram of a differential encoder. Figure 6 is a functional block diagram of an OFDM receiving apparatus of the present invention. Figure 7 is a functional block diagram of the D2PSK demodulator. 25 [Key component symbol description] 13 1260879 12 Encoder 14 Conventional modulator 16 Sequence 歹 1J / Parallel converter 18 IFFT 20 Parallel/sequence converter 22 Cyclic precoder 24 Digital/analog converter 26 Digital/analog Converter 30 Modulator 32 Sequence / Parallel Converter 34 Differential Encoder 36 Unit Phase Shift Keying Modulator 40 Demodulation Transducer
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