201114231 六、發明說明： 【發明所屬之技術領域】 本發明係有關於一種多輸入多輸出正交分頻 多工系統（MIMO-OFDM)之傳送端架構，特別係有 關於一種可降低峰值對平均功率比值之 MIMO-OFDM傳送端架構。 【先前技術】 在無線通訊技術中，使用空頻編碼（Space Frequency Block Coding, SFBC)之多重輸入多重 輸出（Multiple-input Multiple-output, ΜΙΜΟ)的正 交分頻多工（orthogonal frequency division multiplexing, OFDM)系統是相當重要的技術之 一，然而，其實際應用上卻存在峰值對平均功率 比值（peak-to-average power ratio，PAPR)過高的 問題，而PAPR過高係會導致系統功率效益降低、 增加裝置耗電及造成訊號失真。為了解決上述問 題，習知已有提出以選擇映射法（selected mapping， SLM)降低PAPR，如第1圖所示，其係將調變 (modulation)後的符元（symbol)，排列在每個子載 波上傳送，複製户組，並分別乘上一隨機相位旋 轉向量R後，經過SFBC編碼器，再通過反快速 傅立葉轉換（inverse fast fourier transform, IFFT) 運算後，得到時域上的候選訊號，而不同的隨機 相位旋轉向量可以得到不同的候選訊號，再從該 201114231 些候選訊號中找出一具有最小PAPR的訊號傳 送’習知選擇映射法雖可有效降低PAPR，但其所 需運算複雜度過高，如在M根天線的傳送端架構 下欲產生/>個候選訊號，就需要M户個反快速傅 立葉轉換運算’其難以實際應用於現今系統中。 【發明内容】 本發明之主要目的係在於提供一種可降低峰 值對平均功率比值之MIMO-OFDM傳送端架構， 其包含一空頻編碼單元、一訊號產生單元、一循 環位移和旋轉相位單元、一訊號向量相加器、一 天線訊號產生器以及一比較器，該訊號產生單元 係連接該空頻編碼單元，該循環位移和旋轉相位 單元係連接該訊號產生單元，該訊號向量相加器 及該天線訊號產生器係連接該循環位移和旋轉相 位單元，而該比較器係連接該訊號向量相加器及 該天線訊號產生器，本發明係利用該訊號產生器 之V個長度為點的反快速傅立葉轉換器產生 出Μ根傳送天線的訊號，再利用重複的特性將 長度的時域訊號向量複製出完整長度為#的 子載波群向量，並藉由該循環位移和旋轉相位單 元改變訊號相位，最後將個不同的子載波群重 新組合出各天線所需傳輸的資料向量，如此，將 可使得運算量大幅減少，本發明在功效上除了可 降低PAPR外，亦可大幅降低運算複雜度。 201114231 【實施方式】 請參閱第2圖，其係本發明之一較佳實施 例，一種可降低峰值對平均功率比值之 画Ο-OFDM傳送端架構係包含^編碼單元 1〇、一訊號產生單元20、一循環位移和旋轉相位 單元30、一訊號向量相加器4〇、一天線訊號產生 器50以及一比較器60，在本實施例中，該訊號 產生單元20係連接該空頻編碼單元1〇，且用以 產生11個<的向量，該訊號產生單元2〇係包含有 u個反快速傅立葉轉換器21、（υ_υ個向量乘法器 22及一訊號分部與係數相乘複製器23，在本實施 例中，各該反快速傅立葉轉換器之長度係為 N/U，而U及Ν皆為2的幂次方，此外，⑴心）個 向量乘法器22係分別連接個反快速傅立葉 轉換器21，而該訊號分部與係數相乘複製器23 係連接（u-i)個向量乘法器22，此外，在本實施例 中，該訊號分部與係數相乘複製器23亦連接第一 個反快速傅立葉轉換器21，請再參閲第2圖，該 ，環位移和旋轉相位單元30係連接該訊號產生 單元20之該訊號分部與係數相乘複製器23，其 係用以改變該訊號分部與係數相乘複製器23輸 出訊號之相位，又，在本實施例中，該訊號向量 相加器40及該天線訊號產生器5〇係連接該循環 位移和旋轉相位單元3〇，而該比較器係連接 201114231 該訊號向量相加器4rt β ^ 窃40及該天線訊號產生器50。 關於本發明之傳送端架構的工作原理係詳細 說明如下°考慮-個SFBC _〇.〇刪系統有 从根天鎳與AM固子載波，每V個子载波組成一個 頻域子區塊（Subbloek)，每個頻域子區塊包含β 個調變符碼，因此編碼矩❸可寫成—個㈣的矩 陣：201114231 VI. Description of the Invention: [Technical Field] The present invention relates to a transmission end architecture of a multiple input multiple output orthogonal frequency division multiplexing system (MIMO-OFDM), in particular to a peak-to-average reduction Power ratio MIMO-OFDM transmitter architecture. [Prior Art] In the wireless communication technology, orthogonal frequency division multiplexing (Multiple-input Multiple-output, SF) using Space Frequency Block Coding (SFBC) is used. OFDM) system is one of the most important technologies. However, in practice, there is a problem that the peak-to-average power ratio (PAPR) is too high, and the PAPR is too high, which leads to system power efficiency. Reduce, increase the power consumption of the device and cause signal distortion. In order to solve the above problem, it has been proposed to reduce the PAPR by a selective mapping (SLM). As shown in FIG. 1, it is to arrange a symbol after modulation in each subcarrier. After transmitting, copying the group, and multiplying the random phase rotation vector R by the SFBC encoder, and then performing the inverse fast Fourier transform (IFFT) operation, the candidate signals in the time domain are obtained, and Different random phase rotation vectors can obtain different candidate signals, and then find a signal transmission with minimum PAPR from the 201114231 candidate signals. The conventional selection mapping method can effectively reduce the PAPR, but the required computational complexity is High, such as the generation of /> candidate signals under the transmission structure of the M antennas, requires an M-subverse fast Fourier transform operation' which is difficult to practically apply in today's systems. SUMMARY OF THE INVENTION The main object of the present invention is to provide a MIMO-OFDM transmission end architecture capable of reducing a peak-to-average power ratio, comprising a space frequency coding unit, a signal generation unit, a cyclic shift and a rotational phase unit, and a signal. a vector adder, an antenna signal generator, and a comparator, wherein the signal generating unit is coupled to the space frequency encoding unit, the cyclic shift and rotational phase unit is coupled to the signal generating unit, the signal vector adder and the antenna The signal generator is connected to the cyclic shift and rotational phase unit, and the comparator is connected to the signal vector adder and the antenna signal generator. The invention utilizes V length-point inverse fast Fouriers of the signal generator The converter generates a signal of the root transmitting antenna, and then uses the repeated characteristic to copy the length time domain signal vector to the subcarrier group vector of complete length #, and changes the signal phase by the cyclic shift and the rotating phase unit, and finally Reassembling a different subcarrier group out of the data vector to be transmitted by each antenna, The calculation can be substantially reduced so that, in addition to the present invention can reduce PAPR, but also significantly reduce the computational complexity on the efficacy. 201114231 [Embodiment] Please refer to FIG. 2, which is a preferred embodiment of the present invention, which can reduce the peak-to-average power ratio. The OFDM transmission end architecture includes a coding unit 1 and a signal generation unit. 20. A cyclic shift and rotation phase unit 30, a signal vector adder 4A, an antenna signal generator 50, and a comparator 60. In this embodiment, the signal generating unit 20 is coupled to the space frequency encoding unit. 1〇, and used to generate 11 <<> vectors, the signal generating unit 2 includes u anti-fast Fourier transformers 21, (υ_υ vector multiplier 22, and a signal division and coefficient multiplier replicator) 23, in this embodiment, the length of each of the inverse fast Fourier transformers is N/U, and U and Ν are both powers of 2, and further, (1) heart) vector multipliers 22 are respectively connected to each other. The fast Fourier transformer 21 is connected to the coefficient multiplying replicator 23 by a (ui) vector multiplier 22. Further, in the present embodiment, the signal section is also connected to the coefficient multiplying replicator 23. First anti-fast Fourier For the converter 21, please refer to FIG. 2 again. The ring displacement and rotation phase unit 30 is connected to the signal segment of the signal generating unit 20 and the coefficient multiplying replicator 23 for changing the signal segment. Multiplying the coefficient by the replicator 23 to output the phase of the signal. Further, in the present embodiment, the signal vector adder 40 and the antenna signal generator 5 are connected to the cyclic shift and rotational phase unit 3〇, and the comparison is performed. The device is connected to the 201114231 signal vector adder 4rt β thief 40 and the antenna signal generator 50. The working principle of the transmitting end architecture of the present invention is described in detail below. The SFBC _ 〇 〇 〇 system has a frequency domain sub-block (Subbloek) composed of the root nickel and the AM solid subcarriers. Each frequency domain sub-block contains β modulation codes, so the coding matrix can be written as a (four) matrix:
s 夕丨‘〇夕丨,1 *^2,0 ^2,1 ,υ-ι ,u-\ 其中 Q-\ , 5^=EKu,9-^]+vm>u>9.rb]),s 夕丨'〇夕丨,1 *^2,0 ^2,1 ,υ-ι ,u-\ where Q-\ , 5^=EKu,9-^]+vm>u>9.rb]) ,
而 /V,與匕,為複數值（complex value)，w = i，2,···从， 且/b]是頻域子區塊中第9個調變符碼。若要完整 的考慮各個頻域子區塊的編碼，其係可改寫成 •C = £(/W冲G+d+匕,，,./[⑽切])， q=0 其中*係為頻域子區塊的索引（index)，且 ^> = 0，1，···，Α7ί/-1，因此第m根傳送天線向量可表示為 _ Ύ 之=M，。，…，*丨 X，。…，從1，…，必:； ^ V 1 1 —-/ ~ > 4 、 《V 1 —' 201114231 ，在本實施例中，為了得到時域上超取樣 (over-sampling)後的訊號，其係將中間加入α—ο.ΛΓ 個0，以組成一 lxjw的向量，表示如下 X. g,。，…，丨，…，C，C2' …』, b=0And /V, and 匕, are complex values, w = i, 2, ···· from, and /b] is the ninth modulation code in the frequency domain sub-block. To fully consider the coding of each frequency domain sub-block, its system can be rewritten as •C = £(/W rush G+d+匕,,,./[(10)cut]), q=0 where * is the frequency The index of the domain sub-block, and ^> = 0,1,···,Α7ί/-1, so the m-th transmit antenna vector can be expressed as _ Ύ = M,. ,...,*丨 X,. ..., from 1,..., must:; ^ V 1 1 —-/ ~ > 4 , “V 1 —' 201114231 , in this embodiment, in order to obtain over-sampling signals in the time domain , the system will add α - ο. ΛΓ 0 in the middle to form a vector of lxjw, which represents the following X. g,. ,...,丨,...,C,C2' ...』, b=0
NfU~\ m，0 ， S： N!V-\ ,(/-1NfU~\ m,0 , S: N!V-\ ,(/-1
b^NIVA 其中z為超取樣（over-samp ling)倍數，w為子 載波個數。利用在時域上去取代頻域上運算的技 巧’來解決尚運算複雜度上的問題，而在時域上 對訊號作模數；v循環位移w個單位，即 x[((«-哼冲]，可發現在頻域上的子載波訊號 將會呈現累進旋轉角度效果的相位旋轉，並且不 會使訊號的能量改變，其中”的表示方式如 ,2idc 、 。在本實施例中，兩個 時域訊號向量分別為心和、，而其各自經過離散 傅立葉轉換後的頻域訊號向量分別為尤和，且 彼此間關係如、《，# 4乘上一個常數;系數, 時，、相對應的需要乘上一個常數係數，•，才能維 持相對的關係。又’在本實施例+，其係將讀子 載波分成"群，且在系統分離出的向量後，該循 %位移和旋轉相位單元3〇係分別對4 的循 環位移量與乘\的旋轉相位，以得到心同相 Μ訊號V.’伽〜ω ’其中^可有效 201114231 即省稷數乘法H，另外，當％=〇與％ =1時，即代表 未作相位旋轉之原始傳輸的天線訊號向量。最 後，請參閱第2及3圖，利用該天線訊號產生器 50將c/個不同的向量 < 重新組合出各天線所需傳 輸的貝料向量’在本實施例中，第w根天線的第P組 候選訊號可表示為 且C的第《個元素可以Eq(l)表示如下： U-\ , ZKu,q m) 本發明主要利用該訊號向量相加器40進行必}向 量的線性組合來產生第一根天線所需傳送的訊號 向量’而該天線訊號產生器50則用以產生第二根 天線至第m根天線的訊號，該比較器60則用以比 較候選訊號之PAPR，並選出具有最小PAPR之後 選訊號。 本發明係利用該訊號產生器20之¢/個長度 為#/(/點的反快速傅立葉轉換器21產生出M根 傳送天線的訊號，再利用該訊號分部與係數相乘 複製器23將7V/C7長度的時域訊號向量複製出完整 長度為iV的子載波群向量，並藉由該循環位移和 旋轉相位單元30改變訊號相位，最後將u個不 同的子載波群重新組合出各天線所需傳輸的資料 201114231 ，量’如此’將可使得運算量大幅減少、，本發明 算Si除了可降低―外，亦可大幅降低運 本發明之保護範圍當視後附之申請專利範 所界疋者為準，任何熟知此項技藝者，在不脫離 本發明之精神和範圍内所作之任何變化與修改， 均屬於本發明之保護範圍。 【圖式簡單說明】 第1圖：習知選擇映射法之傳送端架構示意圖。 第2圖.依據本發明之一較佳實施例，一種可降b^NIVA where z is the over-sampling multiple and w is the number of subcarriers. Using the technique of replacing the operation in the frequency domain in the time domain to solve the problem of the computational complexity, and modulating the signal in the time domain; v cyclically shifting w units, that is, x[((«-哼冲], it can be found that the subcarrier signal in the frequency domain will exhibit a phase rotation of the progressive rotation angle effect, and will not change the energy of the signal, wherein "the representation is as follows, 2idc, in this embodiment, two The time domain signal vectors are respectively the heart sum, and their respective frequency domain signal vectors after discrete Fourier transform are respectively summed, and the relationship between them is, for example, "# 4 multiplied by a constant; coefficient, time, and corresponding The need to multiply a constant coefficient, in order to maintain the relative relationship. In this embodiment +, it divides the read subcarrier into a group, and after the vector separated by the system, the % displacement and rotation The phase unit 3 is a cyclic displacement amount of 4 and a rotation phase of the multiplication, respectively, to obtain a cardiac in-phase signal V. 'gamma ~ ω ' where ^ can be effective 201114231, that is, the number of times multiplication H, in addition, when % = 〇 When % =1, it means no The original transmitted antenna signal vector of the bit rotation. Finally, please refer to Figures 2 and 3, using the antenna signal generator 50 to recombine c/different vectors < In this embodiment, the Pth group candidate signal of the wth antenna can be represented as and the "th element of C" can be represented by Eq(l) as follows: U-\, ZKu, qm) The present invention mainly uses the signal vector addition. The device 40 performs a linear combination of vectors to generate a signal vector to be transmitted by the first antenna, and the antenna signal generator 50 generates a signal for the second antenna to the mth antenna. The comparator 60 The PAPR is used to compare the PAPR of the candidate signal, and the selection signal having the minimum PAPR is selected. The present invention generates the M transmitting antenna by using the anti-fast Fourier transformer 21 of the signal generator 20 and having a length of #/(/point). The signal is then used by the signal division and coefficient multiplier replicator 23 to copy the 7V/C7 length time domain signal vector out of the full length iV subcarrier group vector, and is changed by the cyclic shift and rotation phase unit 30. Signal phase, finally u different subcarrier groups recombine the data to be transmitted by each antenna 201114231, the quantity 'so' will make the calculation amount greatly reduced, and the calculation of the Si in addition to the invention can greatly reduce the operation of the invention. The scope of protection is subject to the scope of the patent application, and any changes and modifications made by those skilled in the art without departing from the spirit and scope of the invention are within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a transmission end architecture of a conventional selection mapping method. FIG. 2 is a diagram of a preferred embodiment of the present invention.
低峰值對平均功率比值之MIMO-OFDM 傳送端架構示意圖。 第3圖：依據本發明之一較佳實施例，天線訊號 產生器之構造示意圖。 【主要元件符號說明】 1 0空頻編碼單元 2 0訊號產生單元 21反快速傅立葉轉換器 22向量乘法器 23訊號分部與係數相乘複製器 3 0循環位移和旋轉相位單元 40訊號向量相加器 50天線訊號產生器 60比較器Schematic diagram of the MIMO-OFDM transmission architecture with low peak-to-average power ratio. Figure 3 is a block diagram showing the construction of an antenna signal generator in accordance with a preferred embodiment of the present invention. [Major component symbol description] 1 0 space frequency coding unit 2 0 signal generation unit 21 inverse fast Fourier transformer 22 vector multiplier 23 signal division and coefficient multiplication replicator 3 0 cyclic displacement and rotation phase unit 40 signal vector addition 50 antenna signal generator 60 comparator