E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical space-time processing for wireless communications, " IEEE Transactions on Communications, vol. 48, no. 10, pp. 1669--1680, October 2000.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....this paper, we deal with doubly selective (time and frequency selective) channels. We rely on a Basis Expansion Model (BEM) for doubly selective channels, which incorporates time variation explicitly. The BEM has previously been used in [15] and has been extended to include the spacedimension in [13]. Note that the models in [15] 13] fit within the framework of the more general BEM introduced in [22] 6] Relying on this BEM for doubly selective channels, we then develop a channel independent block spreading scheme that preserves mutual orthogonality among users at the receiver. This ....

....(time and frequency selective) channels. We rely on a Basis Expansion Model (BEM) for doubly selective channels, which incorporates time variation explicitly. The BEM has previously been used in [15] and has been extended to include the spacedimension in [13] Note that the models in [15] [13] fit within the framework of the more general BEM introduced in [22] 6] Relying on this BEM for doubly selective channels, we then develop a channel independent block spreading scheme that preserves mutual orthogonality among users at the receiver. This orthogonality enables separation of the ....

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E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical Space-Time Processing for Wireless Communications," IEEE Transactions on Communications, vol. 48, no. 10, pp. 1669--1680, October 2000.

....antenna elements. These copies can be e#ciently combined using space time processing techniques to combat MAI and to provide array gain. A number of combined linear multiuser detection and array processing techniques have been developed for enhancing the performance of CDMA systems (see e.g. 11] [14]. In this paper, we study blind linear space time multiuser detectors based on the constrained MOE principle. Temporal MOE detectors achieve good performance in multipath environments where the delay spread is limited to a portion of the symbol interval by exploiting knowledge of the desired ....

E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical Space-Time Processing for Wireless Communications," IEEE Trans. Communications, vol. 48, no. 10, pp. 1669-1680, Oct. 2000.

.... Gamma 0 )T )sinc( Gamma 0 )B)d 0 d 0 di 0 ; 5) where sinc(x) sin(x) x) and H i ( 1 p 1= 2 Gammai 2 H sin Gamma1 (i) The number of terms in (3) are determined by L = dTmBe, K = dTB d e and P = dD e S a e where e S a = sin(S a =2) Proof (sketch) [5]: Via a change of variables OE i : i = sin(OE) in (1) s ff (t) can be written as s ff (t) Z e Sa=2 Gamma e Sa=2 Z B d GammaB d Z Tm 0 H i ( q(t Gamma )e j2 t e Gammaj 2iff did d = Z g ff (t; f)Q(f)e j2f t df ; 6) where Q(f) is the Fourier transform of q(t) and g ff (t; ....

....is s(t) L X l=0 M X m= GammaM P X p= GammaP H mlp q mlp (t) 0 t T ; 12) for some canonical channel coefficients H mlp . 4 3 Discussion While the canonical representation (12) is quite general, it is particularly advantageous in the context of spread spectrum (TB AE 1) signaling [5, 6]. First, it provides a robust and maximally parsimonious characterization of space time propagation effects in terms of the fixed basis (4) It eliminates the need for estimating arbitrary delays, Doppler shifts and DOAs of dominant scatterers. 2 Second, the representation provides a versatile ....

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E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical space-time processing in wireless communications," in preparation.

.... ideal front end processing matched to all the dominant multipaths and corresponding DOAs. In addition to suffering from high computational complexity in dense multipath environments, such receivers rely on accurate nonlinear estimation of the delay and DOA parameters of dominant scatterers. In [2, 3], we introduced the canonical space time coordinate (CSTC) system, which provides a parsimonious characterization of the received signal in terms of fixed basis corresponding to certain discrete multipath delays and DOAs of the signaling waveform. These fixed space time basis waveform define a ....

....and identically distributed Bernoulli random variables. n(t) is a zero mean complex Gaussian noise vector with E[n(t)n H (t 0 ) oe 2 I R ffi(t Gamma t 0 ) independent of fb k g. Due to the essentially bandlimited nature of q k (t) the k th user signal admits a representation [2, 3] s k (t Gamma k ) P k X p=P Gamma k d k L k X l=d k H (k) pl q (k) pl (t) 3) q (k) pl (t) a( p )q k t Gamma l B ; 0 t T (4) 4 Extension to fast fading channels can be developed along the lines of [19, 2, 23] 3 where B is the effective bandwidth, f p ....

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E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical space-time processing for wireless communications," to appear in IEEE Trans. Commun., 2000.

....( The discrete angles, Doppler shifts and delays, i; p ; m=T ; l=B) define the canonical basis waveforms and are independent of the actual physical channel parameters. The canonical directions p satisfy p = p N T d T where d T is the sensor spacing at the transmitter [5, 7]. The representation (10) decomposes the channel into virtual channels defined by the basis waveforms (11) The basis waveforms are fixed a priori and their number depends on the multipath, Doppler and angular channel spreads. All temporal variations in physical channel characteristics are ....

....array response matrix AC is given by AC = a( GammaP ) a( P ) 14) In order to analyze the performance of transceivers based on the representation (10) it is advantageous to represent in an equivalent form in which the channel coefficient matrix HC is vectorized. Following [7], we can express s C (t) as s C (t) UCQC (t)h C ; where (15) QC (t) diagf C (t)g Omega I 2P 1 ; C (t) h e Gammaj 2 Mt T ; e j 2 Mt T i T Omega q 1 (t) q 1 t Gamma L B ; q N T (t) q N T t Gamma L B T ; UC = ones(1; L ....

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E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical space-time processing in wireless communications, " submitted to the IEEE Trans. Commun., Apr. 1999.

.... ideal processing matched to all the dominant multipaths and corresponding DOAs. In addition to suffering from high computational complexity in dense multipath environments, such receivers rely heavily on accurate nonlinear estimation of the delay and DOA parameters of dominant scatterers. In [2], 3] we introduced a canonical characterization of the received signal in terms of the essential degrees of freedom in the channel that are observable at the receiver. These degrees of freedom are captured by a fixed basis corresponding to certain discrete multipath delays and DOAs of the ....

.... 1g are iid equiprobable random variables and the noise n(t) is a zero mean complex Gaussian noise vector with E[n(t)n H (t 0 ) oe 2 I R ffi (t Gamma t 0 ) 1 independent of fb k g. Due to the essentially bandlimited nature of q k (t) the k th user signal admits a representation [2], 3] s k (t Gamma k ) P k X p=P Gamma k dk Lk X l=dk H (k) pl q (k) pl (t) 2) q (k) pl (t) a( p )q k t Gamma l B ; 0 t T where B is the effective bandwidth, f p g R p=1 , Gamma 2 1 2 Delta Delta Delta R 2 are chosen such that ....

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E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical space-time processing for wireless communications," submitted to IEEE Trans. Commun., 1999.

....matched to all the dominant multipaths and corresponding direction of arrivals (DOAs) In addition to suffering from high computational complexity in dense multipath environments, such receivers rely heavily on accurate estimation of the delay and DOA parameters of dominant scatterers. In [2] we introduced a canonical characterization of the received signal in terms of the essential degrees of freedom in the channel that are observable at the receiver. These degrees of freedom are captured by a fixed basis corresponding to certain discrete multipath delays, Doppler shifts, and DOAs of ....

....d d dOE; 1) where b k , E k and k are the symbol, energy, and delay of the k th user, and a(OE) is the array response vector for direction of arrival (DOA) OE. We assume a onedimensional array without loss of generality. H k (OE; is the time frequency spreading function of the channel [2], and q k (t) is the signaling waveform, S Gamma k ; S k ] GammaD k ; D k ] 0; T k ] are the angular, Doppler, and delay spread for the k th user, respectively. Here we assume fb k g 2 f Gamma1; 1g are IID equiprobable Bernoulli random variables and the noise n(t) is a zero mean ....

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E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical space-time processing for wireless communications, " submitted to IEEE Trans. Commun., 1999.

....functions fuklp(t)g, 2 albeit at the expense of a loss of accuracy in the representation (13) in the case of arbitrary multipath delays. The accuracy of (13) can be improved by increasing the oversampling factor O, although at the expense of losing orthogonality of the basis functions fuklp(t)g [4, 2]. 3. COHERENT RECEIVER STRUCTURE Here we address single user binary antipodal communication with coherent reception. We consider a discrete multipath slow fading environment with delay spread Tm T so that intersymbol interference is negligible and symbolby symbol detection suffices. ....

....canonical receivers display an SNR performance loss between 3 dB (O = 1) and 0.5 dB (O = 8) The performance loss in canonical receiver is a consequence of the band limited approximation in (3) and resulting error in the approximation for the received signal. This error decreases as O is increased [4] and the performance loss decreases. Note that the conventional receiver requires estimates of 21 Theta 16 Theta 3 delay, DOA, and fading parameters and implementation of 21 Theta 16 space time filters. In contrast, the canonical receiver with O = 8 only requires estimates of 4 Theta 9 channel ....

E.N. Onggosanusi, A.M. Sayeed and B.D. Van Veen, "Canonical Space-Time Processing in Wireless Communications ", in preparation.

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E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical space-time processing for wireless communications, " IEEE Transactions on Communications, vol. 48, no. 10, pp. 1669--1680, October 2000.

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E. N. Onggosanusi, A. M. Sayeed, and B. D. Van Veen, "Canonical space-time processing for wireless communications," IEEE Trans. Commun., vol. 48, pp. 1669--1680, Oct. 2000.

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