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We analyze a distributed M-user multiple-access problem in both the additive white Gaussian noise channel and the discrete memoryless channel. A system where each user independently chooses a transmission rate according to a probability distribution function is considered. Under the assumption of symmetric capacity regions, we show that the optimal transmission rate distribution is a point mass for...
We extend Shannon's result on the capacity of channels with state information to multiple user channels. More specifically, we characterize the capacity (region) of degraded broadcast channels and physically degraded relay channels where the channel state information is causally available at the transmitters. We also obtain inner and outer bounds on the capacity region for multiple access channels...
We investigate the sum-capacity loss for using uncorrelated Gaussian inputs over multiple-input multiple-output (MIMO) power-constrained linear additive-noise channels in multi-user configurations. We show that the sum-capacity loss is bounded by a universal constant which depends only on the total number of input and output dimensions of the channel, but is independent of the channel matrix, the...
We consider the broadcast-relay channel: a broadcast channel where receivers are permitted to assist in the distribution of data to other receivers by relaying. We extend the previous results and demonstrate that effective transmission strategies can be derived by combining well-known techniques for broadcast and relay channels. Additionally, we derive new outer bounds to capacity regions
In this paper, we investigate throughput performance of downlink multi-antenna transmission schemes exploiting multiuser diversity. The asymptotic analysis is performed based on the extreme value theory. From this analysis, it is demonstrated that the multiuser spatial multiplexing known as the asymptotically optimal transmission scheme is no longer optimal in highly correlated multiple antenna channels
Practical implementation of random binning is one of the key challenges in achieving the largest available rate regions for many multiuser channels. This paper explores the use of low-density parity-check (LDPC) like codes for a particular kind of deterministic broadcast channel called the Blackwell channel and illustrates that random linear codes can be used to construct practical binning schemes...
In this paper, we define the power region as the set of power allocations for K users such that everybody meets a minimum signal-to-interference ratio (SIR). The SIR is modeled in a multiuser CDMA system with fixed linear receiver and signature sequences. We show that the power region is convex in linear and logarithmic scale. It furthermore has a component-wise minimal element. Power constraints...
In this paper, we consider both the down-link and up-link of a cellular communication system operated under strict delay constraints. We further assume that, except for the one-bit ACK/NACK signal associated with the automatic retransmission request (ARQ) protocol, no channel state information (CSI) is available at the transmitter(s). In this setting, we establish the critical role of multi-user diversity...
This paper studies finite-terminal random multiple access over a standard multi-packet reception (MPR) channel. In the first part of the paper, we show that if the MPR channel is standard, the throughput region of random multiple access is co-ordinate convex. We then study the information capacity region of multiple access without code synchronization and feedback. We show that the asymptotic capacity...
In this paper, we consider a downlink communication system, in which a base station (BS) equipped with M antennas communicates with N users each equipped with K receive antennas. We propose an efficient suboptimum algorithm for selecting a set of users in order to maximize the sum-rate throughput of the system. For the asymptotic case of N rarr infin, it is shown that by using a very simple preceding...
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