B. D. Hart and D. P. Taylor, "Extended MLSE diversity receiver for the time- and frequency-selective channel," IEEE Trans. Commun., vol. 45, pp. 322--333, Mar. 1997.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....of ISI are relatively negligible due to the excellent autocorrelation properties of pseudo random codes. Thus, a one shot detector which ignores ISI may be used at the receiver for most practical situations. 4. 1 Optimal Detector We first derive the optimal maximum likelihood sequence detector [13, 14, 15]. Conditioned on the channel coefficients and the symbol sequence, the log likelihood function can be written as (r(t) fh i n;k g; fb i g) Gamma Z 1 Gamma1 fi fi fi fi fi r(t) Gamma X i X n;k b i h i n;k u i n;k (t) fi fi fi fi fi 2 dt (8) 2 A pilot signal may ....

....An analysis of the effect of estimation errors on performance is, however, beyond the scope of this paper. 7 where h i n;k 4 = Tc Te b H i ( k Te ; nT c ) Neglecting the terms independent of the symbol sequence, we can reduce this expression to obtain an iterative metric given by [13, 15] X i 2 Re 8 : X n;k Gamma b i z i n;k h i n;k Delta Gamma i Gamma1 X l=i GammaI 1 b i b l X n 0 ;k 0 ;n;k h i n 0 ;k 0 h l n;k R i;l n 0 ;k 0 ;n;k 9 = 9) where z i n;k = Z r(t)u i n;k (t)dt = Z r(t)q (t Gamma iT Gamma ....

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B. D. Hart and D. P. Taylor, "Extended MLSE diversity receiver for the time- and frequencyselective channel," IEEE Transactions on Communications, vol. 45, no. 3, pp. 322--333, Mar 1997.

....excellent autocorrelation properties of pseudo random codes. Thus, a one shot detector which ignores ISI and employs maximal ratio diversity combining may be used at the receiver for most practical situations. 4. 1 Optimal Detector We first derive the optimal maximum likelihood sequence detector [18, 19, 20]. Conditioned on the channel coefficients and the symbol sequence, the log likelihood function can be written as (r(t) fh i n#k g# fb i g) Z 1 ;1 fi fi fi fi fi r(t) X i X n#k b i h i n#k u i n#k (t) fi fi fi fi fi 2 dt (9) where h i n#k 4 = Tc Ts b H i ( k Ts #nT c ....

.... g# fb i g) Z 1 ;1 fi fi fi fi fi r(t) X i X n#k b i h i n#k u i n#k (t) fi fi fi fi fi 2 dt (9) where h i n#k 4 = Tc Ts b H i ( k Ts #nT c ) Neglecting the terms independent of the symbol sequence, we can reduce this expression to obtain an iterative metric given by [18, 20] 1 X i= 1 2Re 8 : X n#k ; b i z i n#k h i n#k Delta ; i;1 X l=i;I 1 b i b l X n 0 #k 0 #n#k h i n 0 #k 0 h l n#k R i#l n 0 #k 0 #n#k 9 = # # (10) where z i n#k = Z iT nTc Ts iT nTc r(t)u i n#k (t)dt = Z iT nTc Ts iT nTc r(t)q (t ; ....

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B. D. Hart and D. P.Taylor, "Extended MLSE diversity receiver for the time- and frequency-selective channel," IEEE Transactions on Communications, vol. 45, no. 3, pp. 322--333, Mar 1997.

....autocorrelation properties of pseudorandom codes. Thus, a oneshot detector, which ignores ISI and employs maximal ratio diversity combining, may be used at the receiver for most practical situations. A. Optimal Detector We first derive the optimal maximum likelihood sequence detector [18] [20]. Conditioned on the channel coefficients and 2 A pilot signal may be used to estimate these channel coefficients. This can be done in principle as long as the channel is underspread, i.e. B T (1=2) 15] 16] Most practical channels are underspread [1] 17] including the examples discussed ....

....of this paper. 86 IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 48, NO. 1, JANUARY 2000 the symbol sequence, the log likelihood function can be written as (9) where . Neglecting the terms independent of the symbol sequence, we can reduce this expression to obtain an iterative metric given by [18] [20] (10) where (11) are the correlator outputs corresponding to the multipath Doppler shifted versions of the th transmitted symbol, and (12) is the correlation between the multipath Doppler waveforms for the th and th symbols. It is evident from the optimal metric in (10) that given the channel ....

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B. D. Hart and D. P. Taylor, "Extended MLSE diversity receiver for the time- and frequency-selective channel," IEEE Trans. Commun., vol. 45, pp. 322--333, Mar. 1997.

....components (ae = 0:05) As evident from Figure 6, the values of ae = 0:0125; 0:05, and 0:1 are achieved at relatively small values of TB d : 0:2; 0:39, and 0:6, respectively. We note that similar gains, implicitly due to Doppler diversity, have been reported in other non CDMA systems as well [14]. 9 Similar instance of small causes leading to large effects have been observed in other related contexts as well [16, 17] Finally, Figure 8 illustrates the multipath Doppler diversity gains realistically achievable in practice compared to the RAKE receiver with 2 multipath components. Note ....

B. Hart and D. P. Taylor, "Extended MLSE diversity receiver for the time- and frequency-selective channel," IEEE Trans. Commun., vol. 45, pp. 322--333, Mar. 1997.

....excellent autocorrelation properties of pseudo random codes. Thus, a one shot detector which ignores ISI and employs maximalratio diversity combining may be used at the receiver for most practical situations. 4. 1 Optimal Detector We first derive the optimal maximum likelihood sequence detector [18, 19, 20]. Conditioned on the channel coefficients and the symbol sequence, the log likelihood function can be written as (r(t) fh i n;k g; fb i g) Gamma Z 1 Gamma1 fi fi fi fi fi r(t) Gamma X i X n;k b i h i n;k u i n;k (t) fi fi fi fi fi 2 dt (9) where h i n;k 4 = Tc Ts b H ....

.... Z 1 Gamma1 fi fi fi fi fi r(t) Gamma X i X n;k b i h i n;k u i n;k (t) fi fi fi fi fi 2 dt (9) where h i n;k 4 = Tc Ts b H i ( k Ts ; nT c ) Neglecting the terms independent of the symbol sequence, we can reduce this expression to obtain an iterative metric given by [18, 20] 1 X i= Gamma1 2 Re 8 : X n;k Gamma b i z i n;k h i n;k Delta Gamma i Gamma1 X l=i GammaI 1 b i b l X n 0 ;k 0 ;n;k h i n 0 ;k 0 h l n;k R i;l n 0 ;k 0 ;n;k 9 = 10) where z i n;k = Z iT nTc Ts iT nTc r(t)u i n;k (t)dt = Z iT ....

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B. D. Hart and D. P. Taylor, "Extended MLSE diversity receiver for the time- and frequencyselective channel," IEEE Transactions on Communications, vol. 45, no. 3, pp. 322--333, Mar 1997.

....(e mail: pas comm.utoronto.ca) Publisher Item Identifier S 0090 6778(00)07532 2. SER) and perform soft input soft output detection suitable for iterative (Turbo) decoding [6] 7] However, although there is rich literature on MLSDs for time varying frequency selective channels [4] 5] [8] [11] the MAP research is less complete [6] 12] 15] In this unified paper, we provide a novel performance analysis of MAPDs in time varying channels, and we coherently and comprehensively address the following practically important topics found also in the MLSD literature: linear ....

.... address the following practically important topics found also in the MLSD literature: linear modulations, time varying frequency selective channels, differential phase detection, fractional sampling, and detection when the channel impulse response (CIR) is known (the known CIR MAPDs [8]) or averaged over (the predictor MAPDs [9] 11] Averaging over the CIR is tractable when its probability density function (pdf) is Gaussian (Rayleigh or Rician fading) but the CIRs mean, the channel autocovariance and the noise variance must be known, and a finite memory approximation on the ....

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B. D. Hart and D. P. Taylor, "Extended MLSE diversity receiver for the time- and frequency-selective channel," IEEE Trans. Commun., vol. 45, pp. 322--333, Mar. 1997.

....sum of the diversity sources branch metrics, which are each calculated separately. However, when the diversity sources are correlated, the correlation can be exploited to improve prediction. This is unlike the case of the known channel, where correlation between diversity sources has no influence [2]. Correlated diversity sources arise for instance in space diversity when antennae are not located at the zeroes of the other antennae s spatial correlation functions. This letter is organised as follows. In section II, the signal model is described. In section III, the MLSE receiver for ....

B.D.Hart, D.P.Taylor, "Extended MLSE Diversity Receiver for the Time- and FrequencySelective Channel," IEEE Trans. Comm., vol. 45, no. 3, pp322-333, Mar. 1997

....and autocovariance are known (in this context, unknown signifies that the diffuse component is unknown but the specular component is known. This makes most sense when we realise that only zero mean channels have been considered heretofore) 6,7,8,9,10,11] iii) The channel is completely known [17,22]. In (ii) and (iii) the receiver is often described as genie aided, since the receiver is assumed to have knowledge that actually cannot be available. In approach (i) the receiver hypothesises all possible transmitted sequences. For each, it makes an ML estimate of the signal mean and ....

B.D.Hart, D.P.Taylor, "Extended MLSE Diversity Receiver for the Time- and Frequency-Selective Channel," IEEE Trans. Comm., vol. 45, no. 3, pp322-333, Mar. 1997

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