Precoding in Multiantenna and Multiuser Communications

Windpassinger, C.; Fischer, Robert F. H.; Vencel, T.; Huber, Johannes B.

doi:10.1109/twc.2004.830852

Cited by 495 publications

(345 citation statements)

References 42 publications

(61 reference statements)

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“…Our results show that with a similar complexity at the transmitter, our chip-wise solution with only a fixed matched filter (to the original spreading sequence) at the receiver can outperform the TH precoder with a RAKE receiver (i.e. with CSI at the receiver) proposed in [14,15]. Furthermore, efficient algorithms for multiuser power loading and ordering are developed.…”

Section: Introductionmentioning

confidence: 86%

“…If the ISI term Hx[i À 1] were not present in (25) (this is the case when a guard interval is inserted between consecutive symbols), then the TH precoding scheme in [14] for MIMO systems can be directly applied here. In such a case, the TH precoder consists of a feedforward (FF) filter matrix F and a feedback (FB) filter matrix (C 2 I), which are obtained in the following way.…”

Section: Bit-wise Multiuser Thp (Th-bit-original and Th-bit-rake)mentioning

confidence: 99%

“…These results were originally proved for Gaussian channels [6], and have been generalised to other types of causal interference [7][8][9]. Several practical suboptimal implementations of dirty paper coding based on Tomlinson-Harashima (TH) precoding [10,11] have been proposed, for example for digital subscriber line systems [12], for multi-antenna systems [13,14] and CDMA systems [15].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 86%

Section: Bit-wise Multiuser Thp (Th-bit-original and Th-bit-rake)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiuser TH-precoding for TDD–CDMA over multipath channels

2007

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“…Given what has been transmitted, the causal part of ISI can be canceled in advance in designing the waveform of the current symbol. Such a design pholosophy is analogous to the transmitter-based interference pre-subtraction [78]- [80] in the nonlinear precoding literature. A notable distinction for TR systems is that only the causal part of ISI can be canceled while the anti-causal part of ISI cannot be canceled and needs to be suppressed by the waveform design based on channel information [49].…”

Section: A Advanced Waveform Designmentioning

confidence: 99%

Time-Reversal Wireless Paradigm for Green Internet of Things: An Overview

Chen

Han

Yang

et al. 2014

IEEE Internet Things J.

115

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Abstract-In this paper, we present an overview of the timereversal (TR) wireless paradigm for green Internet of Things (IoT). It is shown that the TR technique is a promising technique that focuses signal waves in both time and space domains. The unique asymmetric architecture significantly reduces the cost of the terminal devices, the total number of which is expected to be very large for IoT. The focusing effect of the TR technique can harvest the energy of all the multi-paths at the receiver, which improves the energy efficiency of the wireless transmission and thus the battery life of terminal devices in IoT. Facilitated by the high-resolution spatial focusing, the TR division multiple access scheme leverages the uniqueness of the multi-path profiles in the rich-scattering environment and maps them into location-specific signatures, so that spatial multiplexing can be achieved for multiple users operating on the same spectrum. In addition, the TR system can easily support heterogeneous terminal devices by providing various quality-of-service (QoS) options through adjusting the waveform and rate backoff factor. Finally, the unique location-specific signature in TR system can provide additional physical-layer security and thus can enhance the privacy and security of customers in IoT. All the advantages show that the TR technique is a promising paradigm for IoT.Index Terms-Internet of Things (IoT), spatial focusing, temporal focusing, time reversal (TR), time-reversal division multiple access (TRDMA).

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“…When planning network, the level of beam boundary is usually set by a 3dB decrease of antenna gain [11]. B is precoding matrix, a is output of precoder, data vector p or modulo device at the transmitter is equivalently used to restrict the power of a to a specific range; F is processing matrix at the transmitter; x is the preprocessing output; H is channel gain; n is noise, y is received signal, G is processing matrix at the receiver, r is output of processing matrix G and â is the output of modulo and decision device at the receiver end [3]- [4]. Therefore, the signals at the receiver end can be expressed as …”

Section: System Modelmentioning

confidence: 99%

Resource scheduling for TH-precoding adoption on multi-beam satellite downlink signals

Gao¹,

Zheng

et al. 2014

16th International Conference on Advanced Communication Technology

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Abstract-A resource scheduling scheme which is based on interference pre-cancellation is proposed in this paper for orthogonal frequency division multiple access (OFDMA) multibeam satellite system. Firstly, in order to reuse same channel among beams, Tomlinson-Harashima precoding (TH-Precoding) is introduced to pre-cancel downlink interference of users from different beams. Then, several resource scheduling algorithms are proposed to jointly work with TH-Precoding. Finally, simulations are executed to validate the proposed scheme, which suggest that compared to traditional single frequency reuse scheme, the proposed scheme can successfully eliminate cochannel interference and improve user SINR significantly.

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Precoding in Multiantenna and Multiuser Communications

Cited by 495 publications

References 42 publications

Multiuser TH-precoding for TDD–CDMA over multipath channels

Multiuser TH-precoding for TDD–CDMA over multipath channels

Time-Reversal Wireless Paradigm for Green Internet of Things: An Overview

Resource scheduling for TH-precoding adoption on multi-beam satellite downlink signals

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