Post-IDFT Multidimensional Beamforming for STC-OFDM Systems
-
摘要: 提出了适用于空时编码-正交频分复用(OFDM)系统的后-逆离散傅立叶变换(post-IDFT)多波束形成技术.该技术通过对空频信道相关矩阵进行特征分解获得多个特征模式,再利用空时分组码(STBC)各发射分支信号的正交性使OFDM系统形成多个post-IDFT波束.接收端根据STBC传输矩阵的正交性对多波束解码.系统获得的空间分集增益为空频信道相关矩阵的特征值之和,最大空间分集增益与子载波波束形成方案相同,误码率比STC-OFDM的低.该技术将复杂度降低到子载波波束形成方案的1/S(S为OFDM系统的子载波数目),而且当波束维数(m)小于发射天线数目(M)时,可进一步减少M-m个IDFT模块Abstract: A post-inverse discrete Fourier transform(post-IDFT) multidimensional beamforming scheme was proposed for space-time coded-orthogonal frequency division multiplexing(STC-OFDM) systems.This scheme obtains multiple eigen mode by decomposing cross-matrix of space-frequency channels,and forms multidimensional post-IDFT beamformings for STC-OFDM systems based on the orthogonality of the STBC transmission matrix.The space-diversity gain achieved by the scheme is the sum of the multiple eigen values,and is the same as that of the sub-carrier beamforming,with a lower symbol error rate(SER) than a STC-OFDM does.The proposed scheme reduces the complexity to 1/S(S is the number of subcarriers of an OFDM system) compared with the sub-carrier beamforming;moreover,when the dimension of the post-IDFT beamforming(m) is less than the number of the transmit antennas(M),the system reduces M-m IDFT blocks.
-
Key words:
- OFDM /
- space-time coding /
- beamforming /
- space-diversity
-
WONG K K,CHENG R S K,LETAIEF K B,et al.Adaptive antennas at the mobile and base stations in an OFDM/TDMA systems[J].IEEE Trans.Commun.,2001,49(1):195-206.[2] LEE K F,WILLIAMS D B.A Space-time coded transmitter diversity technique for frequency selective fading channels[C]//IEEE Proc.SAMSPW'00,Cambridge:IEEE Press,2000:149-152.[3] LI Y,SESHADRI N,ARIYAVISITAKUL S.Transmitter diversity of OFDM systems with dispersive fading channels[C]//IEEE Proc.GLOBECOM98,Sydney:IEEE Press,1998:968-973.[4] OKADA M,KOMAKI S.Pre-DFT combining space diversity assisted COFDM[J].IEEE Trans.Veh.Technol.,2001,50(2):487-496.[5] HUANG D,LETAIEF K B,LU J.A receive space diversity architecture for OFDM systems using orthogonal designs[J].IEEE Trans.Wireless Commun.,2004,3 (3):992-1 002.[6] HUANG D,LETAIEF K B.Pre-DFT processing using eigenanalysis for coded OFDM with multiple receive antennas[J].IEEE Trans.Commun.,2004,52(11):2 019-2 027.[7] GANESAN G,STOICA P.Space-time block codes:A maximum SNR approach[J].IEEE Trans.Inform.Theroy,2001,47(4):1 650-1 656.[8] TAROKH V,JAFARKHANI H,CALDERBANK A R.Space-time block codes from orthogonal designs[J].IEEE Trans.Inform.Theory,1999,45(5):1 456-1 467.[9] SKOGLUND M,J NGREN G.Onthe capacity of a multiple-antenna communication link with channel side information[J].IEEE J.Select.Areas Commun.,2003,21(3):395-405.[10] ZHOU S,GIANNAKIS G.Optimal transmitter eigen-beamforming and space-time block coding based on channel mean feedback[J].IEEE Trans.Signal Processing,2002,50(10):2 599-2 613.[11] SAMPATH H,PAULRAJ A.Linear precoding for space time coded systems with known fading correlations[J].IEEE Commun.Lett.,2002,6(6):239-241.[12] ZHOU S,GIANNAKIS G.Optimal transmitter eigen-beamforming and space-fime block coding based on channel correlations[J].IEEE Trans.Inform.Theory,2003,49(7):1 673-1 690.[13] VU M,PAULRAJ A.Optimal Linear precoders for MIMO wireless correlated channels with nonzero mean in space-time coded systems[J].IEEE Trans.Signal Processing,2006,54(6):2 318-2 332.[14] JONGREN G,SKOGLUND M,OTTERSTEN B.Combining beamforming and orthogonal space-time block coding[J].IEEE Trans.Inform.Theory,2002,48(3):611-627.[15] SHIU D S,FOSCHINI G J,GANS M J.Fading correlation and its effect on the capacity of multi-element antenna systems[J].IEEE Trans.Commun.,2000,48(3):502-512.[16] 程佩青.数字信号处理教程[M].北京:清华大学出版社,2001.[17] PROAKIS J G.Digital communications[M].Beijing:Publishing House of Electronics Industry,2001.
点击查看大图
计量
- 文章访问数: 1326
- HTML全文浏览量: 46
- PDF下载量: 325
- 被引次数: 0