John M. Cioffi

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This paper addresses the joint design of transmit and receive beamforming or linear processing (commonly termed linear precoding at the transmitter and equalization at the receiver) for multicarrier multi-input multi-output (MIMO) channels under a variety of design criteria. Instead of considering each design criterion in a separate way, we generalize the(More)
This paper considers the multiuser power control problem in a frequency-selective interference channel. The interference channel is modeled as a noncooperative game, and the existence and uniqueness of a Nash equilibrium are established for a two-player version of the game. An iterative water-filling algorithm is proposed to efficiently reach the Nash(More)
This paper proposes an efficient numerical algorithm to compute the optimal input distribution that maximizes the sum capacity of a Gaussian multiple-access channel with vector inputs and a vector output. The numerical algorithm has an iterative water-filling interpretation. The algorithm converges from any starting point, and it reaches within 1/2 nats per(More)
Multipath signal propagation has long been viewed as an impairment to reliable communication in wireless channels. This paper shows that the presence of multipath greatly improves achievable data rate if the appropriate communication structure is employed. A compact model is developed for the multiple-input multiple-output (MIMO) dispersive spatially(More)
In this paper, we present a finite-granularity, loading algorithm for a Discrete Multitone (DMT) modulation system. The proposed algorithm offers significant implementational advantages over the well-known water-pouring method and the earlier Hughes-Hartogs algorithm, while typically suffering only negligible performance degradation relative to the optimal(More)
This paper studies linear transmit filter design for Weighted Sum-Rate (WSR) maximization in the Multiple Input Multiple Output Broadcast Channel (MIMO-BC). The problem of finding the optimal transmit filter is non-convex and intractable to solve using low complexity methods. Motivated by recent results highlighting the relationship between mutual(More)
This paper investigates the problem of dynamic multiuser subchannel allocation in the downlink of OFDM systems. The assumptions are that the channel model is quasi-static and that the base station has perfect channel information. In traditional TDMA or FDMA systems, resource allocation for each user is nonadaptively fixed, and the water-filling power(More)
This paper describes the “vectored” transmission technique for digital subscriber line (DSL) systems, which utilizes user coordination at the central office or optical network unit. This method exploits the colocation of the downstream transmitters and of the upstream receivers, in order to achieve far-end crosstalk (FEXT) cancellation and perform multiuser(More)