3 research outputs found
Rapid Beam Forming in Smart Antennas Using Smart-Fractal Concepts Employing Combinational Approach Algorithms
Smart antennas offer a broad range of ways to improve wireless system performance. They provide enhanced coverage through range extension, hole filling, and better building penetration. Smart antennas use an array of low gain antenna elements which are connected by a network. Fractal concepts have been used in antenna arrays recently. The important properties of fractal arrays are frequency independent multiband characteristics, schemes for realizing low side lobe designs, systematic approaches to thinning, and the ability to develop rapid beam forming algorithms. In this paper, an attempt has been made to apply assignment of usage time and location tag algorithm for smart antennas combined with the fractal concepts to reduce the computational complexity and enhance resource allocation for rapid beam forming algorithms. Furthermore, two combinational approach algorithms are proposed for peer users within single base station and peer users between different base stations
Exact MIMO Zero-Forcing Detection Analysis for Transmit-Correlated Rician Fading
We analyze the performance of multiple input/multiple output (MIMO)
communications systems employing spatial multiplexing and zero-forcing
detection (ZF). The distribution of the ZF signal-to-noise ratio (SNR) is
characterized when either the intended stream or interfering streams experience
Rician fading, and when the fading may be correlated on the transmit side.
Previously, exact ZF analysis based on a well-known SNR expression has been
hindered by the noncentrality of the Wishart distribution involved. In
addition, approximation with a central-Wishart distribution has not proved
consistently accurate. In contrast, the following exact ZF study proceeds from
a lesser-known SNR expression that separates the intended and interfering
channel-gain vectors. By first conditioning on, and then averaging over the
interference, the ZF SNR distribution for Rician-Rayleigh fading is shown to be
an infinite linear combination of gamma distributions. On the other hand, for
Rayleigh-Rician fading, the ZF SNR is shown to be gamma-distributed. Based on
the SNR distribution, we derive new series expressions for the ZF average error
probability, outage probability, and ergodic capacity. Numerical results
confirm the accuracy of our new expressions, and reveal effects of interference
and channel statistics on performance.Comment: 14 pages, two-colum, 1 table, 10 figure