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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)
Recent results on the throughput achievable with wireless networks have not fully considered multiple antennas and multiuser links. We introduce these topics by giving the transport capacity of the multiple-antenna multiple-access and broadcast channels. We use these topologies at the physical layer of an ad-hoc network to obtain achievable(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)