【正文】 2143341243212/14ccccccccccccccccccccccccccccccccC ， and ? ? ? ?? ? ? ??????????????????????????????????????????222222222222*22*11*11*22*3*3*11*22*22*11*3*333*1*233214/3,4ccccccccccccccccccccccccccccC These codes achieve rate1/2 and rate3/4 respectively, as for their 3antenna ,3 / 4 exhibits the same uneven power problems as C3,3 / 4. An improved version of C4,3 / 4 is ?????????????????1*2*32*1*33*1*23214/3,40000ccccccccccccC which has equal power from all antennas in all timeslots. Decoding One particularly attractive feature of orthogonal STBCs is that maximum likelihood decoding can be achieved at the receiver with only linear processing. In order to consider a decoding method, a model of the wireless munications system is needed. At time t, the signal itr received at antenna j is: jtitni ijjt nsr T ????1 ?, where αij is the path gain from transmit antenna i to receive antenna j, its is the signal transmitted by transmit antenna i and jtn is a sample of additive white Gaussian noise (AWGN). The maximumlikelihood detection rule is to form the decision variables )()(1 1 irR tjint nj jti tT R ?? ?? ?? ?? where δk(i) is the sign of si in the kth row of the coding matrix, εk(p) = q denotes that sp is (up to a sign difference), the (k,q) element of the coding matrix, for i = 1,2...nT and then decide on constellation symbol si that satisfies ? ?? ?? ?hCChhCrhCChhCrrhCrcWHWHwHwHWHwHw ??? ????? Re2m ina r g m ina r gm ina r g? 22, with? the constellation alphabet. Despite its appearance, this is a simple, linear decoding scheme that provides maximal diversity. References [1] Gerard J. Foschini and Michael. J. Gans (January 1998). ―On limits of wireless munications in a fading environment when using multiple antennas‖. Wireless Personal Communications 6 (3): 311–335. [2] Gerard J. Foschini (autumn 1996). ―Layered spacetime architecture for wireless munications in a fading environment when using multielement antennas‖. Bell Labs Technical Journal 1 (2): 41–59. [3] I. Emre Telatar (November 1999). ―Capacity of multiantenna European Transactions on Telemunications , 10 (6): 585–595. [4] Vahid Tarokh, Nambi Seshadri, and A. R. Calderbank (March 1998). Space–time codes for high data rate wireless munication: Performance analysis and code construction. IEEE Transactions on Information Theory 44 (2): 744–765. 譯文 基于 MIMOOFDM 系統(tǒng)的正交空時分組碼 本文介紹了移動通信中的空時碼 , 針對多天線系統(tǒng)提出了空時分組碼的正交設(shè)計理論 , 可以采用高效的調(diào)制技術(shù) (QAM,PSK) ,由多天線同時發(fā)射。s code Orthogonality STBCs as originally introduced, and as usually studied, are orthogonal. This means that the STBC is designed such that the vectors representing any pair of columns taken from the coding matrix is orthogonal. The result of this is simple, linear, optimal decoding at the receiver. Its most serious disadvantage is that all but one of the codes that satisfy this criterion must sacrifice some proportion of their data rate (see Alamouti39。s 1998 paper. An STBC is usually represented by a matrix. Each row represents a time slot and each column represents one antenna39。s transmissions over time. Here, sij is the modulated symbol to be transmitted in time slot i from antenna j. There are to be T time slots and nT transmit antennas as well as nR receive antennas. This block is usually considered to be of 39。s code). Moreover, there exist quasiorthogonal STBCs that achieve higher data rates at the cost of intersymbol interference (ISI). Thus, their errorrate performance is lower bounded by the one of orthogonal rate 1 STBCs, that provide ISI free transmissions due to orthogonality. Higher order STBCs Tarokhet al. discovered a set of STBCs that are particularly straightforward, and coined the scheme39。接收端采用最大似然譯碼可以獲得最大的分集增益。由于正交空時分組編碼發(fā)射矩陣各行之間的正交性 , 可以獲得滿分集增益 , 但是當(dāng)發(fā)射天線數(shù)大于 2時 , 利用復(fù)正交設(shè)計得到的正交空時分組編碼不能達到最大傳輸速率 。雖然是必要的 ,它有多個發(fā)射天線 ,這是沒有必要有多個接 收天線 ,雖然這樣做改進效能。 正交 由于最初的對空時編碼做出的研究 ,并介紹了這樣的 正交 。 此外 ,存在著在利率 ,以達到更高的數(shù)據(jù)傳輸干擾的成本 (ISI)。他們也證明了不能超過 2 個發(fā)射天線可以達到的目 標。他們也體現(xiàn)了簡單的，直線 解碼 是伴隨著他們的編碼方案 ,在完美的 信道狀態(tài)信息 。 在時間 t 上的信號 , jtr 天線接收到的是 : jtitni ijjt nsr T ????1 ?, 是路徑獲得傳送天線嗎接收天線 its 是信號通過傳送天線 i 和 jtn 有一份 添加劑 白色高斯噪聲檢測規(guī)則的就是要形成的決策變量。 參考文獻 [1] Gerard J. Foschini and Michael. J. Gans (January 1998). On limits of wireless munications in a fading environment when using multiple antennas. Wireless Personal Communications 6 (3): 311–335. [2] Gerard J. Foschini (autumn 1996). Layered spacetime architecture for wireless munications in a fading environment when using multielement antennas. Bell Labs Technical Journal 1 (2): 41–59. [3] I. Emre Telatar (November 1999). Capacity of multiantenna gaussian channels. European Transactions on Telemunications , 10 (6): 585–595. [4] Vahid Tarokh, Nambi Seshadri, and A. R. Calderbank (March 1998). Space–time codes for high data rate wireless munication: Performance analysis and code construction. IEEE Transactions on Information Theory 44 (2): 744–765. 外文資料 （二） UnitRate Complex Orthogonal SpaceTime Block Code Concatenated With Turbo Coding SpaceTime Block (STB)code has been an effective transmit diversity technique for bating fading due to its orthogonal design， simple decoding and high diversity gins. In this paper, a unitrate plex orthogonal STB code for multiple antennas in Time Division Duplex (TDD) mode is proposed. Meanwhile, Turbo Coding (TC) is employed to improve the performance of proposed STB code further by utilizing its good ability to bat the burst error of fading channel. Compared with fulldiversity multiple antennas STB codes, the proposed code can implement unit rate and pa