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—Recent theoretical results describing the sum capacity when using multiple antennas to communicate with multiple users in a known rich scattering environment have not yet been followed with practical transmission schemes that achieve this capacity. We introduce a simple encoding algorithm that achieves near-capacity at sum rates of tens of bits/channel(More)
Recent theoretical results describing the sum-capacity when using multiple antennas to communicate with multiple users in a known rich scattering environment have not yet been followed with practical transmission schemes that achieve this capacity. We introduce a simple encoding algorithm that achieves near-capacity at sum-rates of tens of bits/channel-use.(More)
The fading channel is a significant problem in many communications environments. In this paper, we examine the performance of unitary space-time modulation in a time-varying channel. We use a Gauss-Markov model of the continuously varying channel to characterize performance of differential and trained modulation. We find a performance ceiling at high SNR(More)
ecently there has been excitement in the image processing and communication fields about dirty-paper coding. This name comes from " Writing on Dirty Paper, " the title of a 1983 paper by Max Costa [1] on the capacity of a Gaussian channel having interference that is known to the transmitter y s i w = + + (1) where i Q ~ (,) N 0 is the interference , w N ~(More)
The application of MIMO processing techniques in channels that are shared among multiple users is a relatively new problem that is increasingly important as MIMO transmission is put into practical use. In this chapter we specifically consider the multiuser downlink, where a base station with multiple antennas transmits simultaneously to more than one user.(More)
Rapid temporal variations in wireless channels pose a significant challenge for space-time modulation and coding algorithms. This paper examines the performance degradation that results when time-varying flat fading is encountered during space-time modulation. Performance is characterized for a channel having a constant specular component plus a(More)
We analyze the performance of trained and differential space-time modulation for channels with a constant specular component and time-varying diffuse fading. We examine the case where the channel varies from sample to sample within a symbol according to a first-order Gauss-innovations model. We show that the effect of the time-varying diffuse channel can be(More)
—We analyze the performance of trained and differential space-time modulation for channels with a constant specular component and time-varying diffuse fading. We examine the case where the channel varies from sample to sample within a space-time symbol matrix according to a first-order time-varying model. We show that the effect of the time-varying diffuse(More)
We describe a method of using a Lagrange multiplier to make a locally optimal trade off between rate and distortion in the motion search for video sequences, while maintaining a constant bit rate channel. Simulation of this method shows that it gives up to 3.5 dB PSNR improvement in a high motion sequence. A locally rate-distortion (R-D) optimal mode(More)
— A lower bound on the capacity of trained space-time modulation is presented for the case of a time-varying channel. We consider the case where the channel consists of two components of variable strength: a specular component from line-of-sight or strong coherent multipath, and a time-varying diffuse component due to a mobile receiver or scatterers. The(More)