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Zero-forcing precoding

About: Zero-forcing precoding is a(n) research topic. Over the lifetime, 3567 publication(s) have been published within this topic receiving 76529 citation(s). more


Open accessJournal ArticleDOI: 10.1109/TIT.2008.926344
Abstract: For the fully connected K user wireless interference channel where the channel coefficients are time-varying and are drawn from a continuous distribution, the sum capacity is characterized as C(SNR)=K/2log(SNR)+o(log(SNR)) . Thus, the K user time-varying interference channel almost surely has K/2 degrees of freedom. Achievability is based on the idea of interference alignment. Examples are also provided of fully connected K user interference channels with constant (not time-varying) coefficients where the capacity is exactly achieved by interference alignment at all SNR values. more

Topics: Zero-forcing precoding (62%), Interference (communication) (55%), Channel capacity (54%) more

3,299 Citations

Open accessJournal ArticleDOI: 10.1109/JSTSP.2014.2334278
Abstract: Millimeter wave (mmWave) cellular systems will enable gigabit-per-second data rates thanks to the large bandwidth available at mmWave frequencies. To realize sufficient link margin, mmWave systems will employ directional beamforming with large antenna arrays at both the transmitter and receiver. Due to the high cost and power consumption of gigasample mixed-signal devices, mmWave precoding will likely be divided among the analog and digital domains. The large number of antennas and the presence of analog beamforming requires the development of mmWave-specific channel estimation and precoding algorithms. This paper develops an adaptive algorithm to estimate the mmWave channel parameters that exploits the poor scattering nature of the channel. To enable the efficient operation of this algorithm, a novel hierarchical multi-resolution codebook is designed to construct training beamforming vectors with different beamwidths. For single-path channels, an upper bound on the estimation error probability using the proposed algorithm is derived, and some insights into the efficient allocation of the training power among the adaptive stages of the algorithm are obtained. The adaptive channel estimation algorithm is then extended to the multi-path case relying on the sparse nature of the channel. Using the estimated channel, this paper proposes a new hybrid analog/digital precoding algorithm that overcomes the hardware constraints on the analog-only beamforming, and approaches the performance of digital solutions. Simulation results show that the proposed low-complexity channel estimation algorithm achieves comparable precoding gains compared to exhaustive channel training algorithms. The results illustrate that the proposed channel estimation and precoding algorithms can approach the coverage probability achieved by perfect channel knowledge even in the presence of interference. more

Topics: Precoding (71%), Zero-forcing precoding (67%), Communication channel (56%) more

1,916 Citations

Journal ArticleDOI: 10.1109/TIT.1981.1056307
Te Sun Han, K. Kobayashi1Institutions (1)
Abstract: A new achievable rate region for the general interference channel which extends previous results is presented and evaluated. The technique used is a generalization of superposition coding to the multivariable case. A detailed computation for the Gaussian channel case clarifies to what extent the new region improves previous ones. The capacity of a class of Gaussian interference channels is also established. more

Topics: Co-channel interference (59%), Z-channel (58%), Zero-forcing precoding (57%) more

1,796 Citations

Open accessJournal ArticleDOI: 10.1109/TWC.2011.060711.101155
Abstract: This paper considers a multi-cell multiple antenna system with precoding used at the base stations for downlink transmission. Channel state information (CSI) is essential for precoding at the base stations. An effective technique for obtaining this CSI is time-division duplex (TDD) operation where uplink training in conjunction with reciprocity simultaneously provides the base stations with downlink as well as uplink channel estimates. This paper mathematically characterizes the impact that uplink training has on the performance of such multi-cell multiple antenna systems. When non-orthogonal training sequences are used for uplink training, the paper shows that the precoding matrix used by the base station in one cell becomes corrupted by the channel between that base station and the users in other cells in an undesirable manner. This paper analyzes this fundamental problem of pilot contamination in multi-cell systems. Furthermore, it develops a new multi-cell MMSE-based precoding method that mitigates this problem. In addition to being linear, this precoding method has a simple closed-form expression that results from an intuitive optimization. Numerical results show significant performance gains compared to certain popular single-cell precoding methods. more

Topics: Zero-forcing precoding (69%), Precoding (67%), MIMO (57%) more

1,251 Citations

Journal ArticleDOI: 10.1109/35.544334
Abstract: Direct-sequence code-division multiple access (DS-CDMA) is a popular wireless technology. In DS-CDMA communications, all of the users' signals overlap in time and frequency and cause mutual interference. The conventional DS-CDMA detector follows a single-user detection strategy in which each user is detected separately without regard for the other users. A better strategy is multi-user detection, where information about multiple users is used to improve detection of each individual user. This article describes a number of important multiuser DS-CDMA detectors that have been proposed. more

1,234 Citations

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Topic's top 5 most impactful authors

Robert W. Heath

44 papers, 7.9K citations

Bjorn Ottersten

24 papers, 664 citations

Symeon Chatzinotas

21 papers, 555 citations

Christos Masouros

16 papers, 646 citations

Syed A. Jafar

14 papers, 4.1K citations

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