Investigation of different fading forecast schemes for flat fading radio channels

Semmelrodt, Sven; Kattenbach, R.

doi:10.1109/vetecf.2003.1284996

Cited by 48 publications

(41 citation statements)

References 13 publications

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“…The best SISO channel predictors have an accurate envelope prediction range (time) of λ/V to 1.5 λ/V in rich multipath scattering environments [12], where λ is the wavelength and V is the vehicle velocity. A CRLB analysis [13] suggests that MIMO channels can be predicted over considerably longer intervals than SISO channels by exploiting the common Doppler shifts of different propagation paths and the spatial structure imposed by the transmit and receive antenna array manifolds.…”

Section: Downlink Time Slotsmentioning

confidence: 99%

MIMO channel prediction results on outdoor collected data

Bidigare

Brown

Kraut

et al. 2013

2013 Asilomar Conference on Signals, Systems and Computers

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Abstract-In this paper we analyze the performance of an autoregressive MIMO channel predictor on outdoor data collected with both vehicular and pedestrian transmitter motion. The metric of performance considered is aggregate beamforming gain obtained using dominant eigenmode MIMO communications when the transmit beamforming vector is chosen based on the channel prediction. We show that while the prediction range obtained on this real data is somewhat less than earlier published results based on simulated data, we are still able to obtain 2X to 3X greater feedback latency tolerance than without using these predictive techniques.

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Section: Downlink Time Slotsmentioning

confidence: 99%

MIMO channel prediction results on outdoor collected data

Bidigare

Brown

Kraut

et al. 2013

2013 Asilomar Conference on Signals, Systems and Computers

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“…When the maximum Doppler shift is f d , a prediction t sec ahead corresponds to prediction of f d t wavelengths. Duel-Hallen et al [25] and Semmelrodt and Kattenbach [27] provide overviews of long-range prediction techniques for fading channels, which include several techniques capable of predicting the channel over more than 1 wavelength.…”

Section: Channel Predictionmentioning

confidence: 99%

“…Hence, with the ESPRIT scheme it is possible to predict the channel gain for the next 1 or 2 fading cycles. Furthermore, the modified covariance method discussed in [27] is capable of predicting the channel for up to 1.5 wavelengths. For the same parameters discussed above, this corresponds to predicting the channel gain for the next 2 to 3 fading cycles.…”

Section: Channel Predictionmentioning

confidence: 99%

Load‐regulated CSMA

Ashraf

Jayasuriya

Perreau

2008

Int J Communication

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SUMMARYIn this paper, we derive throughput of a threshold-based transmission policy, namely load-regulated carrier sense multiple access (CSMA), taking into account the propagation delay of the medium and the offered load at different probabilities of the fading channel. In case of the saturated load-regulated CSMA, a trivial relationship between deterministic offered load to the channel at a particular fading channel condition and the maximum possible offered load has been shown. We further extend the load regulation concept into multi-channel domain. Both single and multi-channel load-regulated CSMA improves the throughput of the system compared with the existing CSMA system, which does not consider channel fading to control the packet transmissions.

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“…On the other hand, in fast fading channels, the channel state that has been estimated during an uplink slot may have changed and the estimate may no longer be accurate for precoding in the next downlink slot. In this case, channel prediction techniques can be used to estimate the future downlink channel state from the current and previous uplink channel estimates, by exploiting the second-order statistics of the fading channel [26] (refer to [27] for a comparison of different channel prediction techniques). Assume that the complex Gaussian fading process of each channel path f k,i (t) follows the Jakes' model [28] with the maximum Doppler spread…”

Section: Th-precoding With Channel Predictionmentioning

confidence: 99%

Multiuser TH-precoding for TDD–CDMA over multipath channels

2007

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Nonlinear precoding schemes for downlink time-division duplex -CDMA systems over multipath fading channels, are considered. First, the capacity results of a downlink CDMA system with either multiuser detection or precoding, were obtained and compared. It is seen that the two schemes exhibit similar capacity regions for both sum rate and maximum equal rate, which motivates the development of efficient nonlinear transmitter precoding techniques to reduce the receiver complexity at the mobile units without degrading the system performance. We then develop both bit-wise and chip-wise Tomlinson -Harashima (TH) multiuser precoding methods for downlink CDMA with multipath, to remove multi-user interference, inter-chip interference and inter-symbol interference. Efficient algorithms for multiuser power loading and ordering are also developed. Implementation of the proposed TH-precoding schemes in time-varying channels based on channel prediction is addressed as well. Simulations results are provided to demonstrate the effectiveness of the proposed techniques in suppressing interference in downlink CDMA. IntroductionMultiuser detection (MUD) techniques are considered powerful for interference suppression in CDMA systems, especially in uplinks, where the base-station receiver has the knowledge of all users' spreading sequences and channel states, and can perform sophisticated signal processing [1]. In the downlinks, however, the mobile receiver typically has only the knowledge of its own spreading sequence and channel state. Although adaptive linear MUD (either training-based or blind) can be employed for such scenario, the performance can be limited because of the linear constraint on the detector. Moreover, the power constraint of the mobile calls for simple receiver processing. On the other hand, the precoding schemes for downlink CDMA effiectively transfer the signal processing for interference suppression from the mobile receiver to the base-station transmitter. This approach is feasible if the base-station can estimate the downlink channels of all users [e.g. in systems employing time-division duplexing (TDD) where the uplink and downlink channels are reciprocal]. In [2], a precoding method was proposed which is essentially an implementation of the RAKE receiver at the transmitter. Hence this approach does not attempt to mitigate the multiple-access interference (MAI). Recently, different linear precoding techniques have been proposed to combat MAI and inter-chip interference but without considering inter-symbol interference (ISI) [3,4]. If the ISI is present then the complexity of these techniques becomes prohibitive since the dimension of the matrix filter is proportional to the data frame length multiplied by the number of users (i.e. block processing). More recently, bit-wise linear precoding methods have been proposed to reduce the precoding complexity in the presence ISI [5]. The downlink CDMA is a special case of broadcast channels. There has been significant recent interest in characterising the ca...

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Investigation of different fading forecast schemes for flat fading radio channels

Cited by 48 publications

References 13 publications

MIMO channel prediction results on outdoor collected data

MIMO channel prediction results on outdoor collected data

Load‐regulated CSMA

Multiuser TH-precoding for TDD–CDMA over multipath channels

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