We study the MIMO broadcast channel and compare the achievable throughput for the optimal strategy of dirty paper coding to that achieved with sub-optimal and lower complexity linear precoding (e.g., zero-forcing and block diagonalization) transmission. Both strategies utilize all available spatial dimensions and therefore have the same multiplexing gain, but an absolute difference in terms of ...

Recently, researchers showed that dirty paper coding (DPC) is the optimal transmission strategy for multiple-input multiple-output broadcast channels (MIMO-BC). In this paper, we study how to determine the maximum weighted sum of DPC rates through solving the maximum weighted sum rate problem of the dual MIMO multiple access channel (MIMO-MAC) with a sum power constraint. We first simplify the ...

We analyze the sensitivity of the capacity of a multi-antenna multi-user system to the number of users being served simultaneously. We show analytically that the capacity loss of serving fewer users at low SNR is much smaller than at high SNR. The advantages of serving fewer users are many: multi-user algorithms often have better performance, lower complexity, and reduced channel-knowledge requ...

Random beamforming (RBF) has received much attention recently in downlink beamforming because of its simple structure, low-feedback load and same throughput scaling as that obtained using dirty paper coding at the transmitter. In this study, the authors analyse the performance of RBF for cognitive downlink multi-antenna system in terms of the throughput of the secondary network. The authors con...

GPS, well known as a versatile, global tool for positioning, has also become the primary system for distributing time and frequency. GPS receivers are fixtures in telecommunication networks, and calibration and testing laboratories. They make it possible to synchronize clocks and calibrate and control oscillators in any facility that can place an antenna outdoors for lineof-sight reception of t...

In this paper, we study the capacity limits of dense multiantenna systems. We derive asymptotic capacity expressions for point-to-point and broadcast channels by applying recent tools from random matrix theory. In the case of broadcast channels, we focus on linear precoding techniques. We found that the asymptotic capacity depends only on the ratio between the size of the antenna array and the ...

We have plotted data from a number of studies on the range of radiofrequency (RF) field levels associated with a variety of environmental and occupational sources. Field intensity is shown in units of volts/meter (V/m) for electric field strength and amps/meter (A/m) for magnetic field strength. Duty factors, modulation frequencies, and modulation indices are also reported for some sources. Thi...

The enormous gains in a multi-antenna transmitter broadcast channel require the Channel State Information at the Transmitter (CSIT). Although the fundamental question “How much feedback is required for a broadcast channel?” has been treated in the literature to some extent, a more comprehensive treatment is certainly desirable. We study the time-division duplex broadcast channel with initial as...

The prescribed Local Area Augmentation System (LAAS) algorithms for the generation of vertical and horizontal protection levels implicitly assume a zero-mean, normally distributed fault-free error model for the broadcast pseudorange corrections. While such a model appears to be consistent with reference receiver ranging errors due to thermal noise and diffuse multipath, remaining errors such as...