The success of LTE heterogeneous networks (HetNets) with macrocells and picocells critically depends on efficient spectrum sharing between high-power macros and low-power picos. Two important challenges in this context are: 1) determining the amount of radio resources that macrocells should offer to picocells, and 2) determining the association rules that decide which user equipments (UEs) should associate with picos. In this paper, we develop a novel algorithm to solve these two coupled problems in a joint manner. Our algorithm has provable guarantee, and furthermore, it accounts for network topology, traffic load, and macro-pico interference map. Our solution is standard compliant and can be implemented using the notion of Almost Blank Subframes (ABS) and Cell Selection Bias (CSB) proposed by LTE standards. We also show extensive evaluations using RF plan from a real network and discuss self-optimized networking (SON)-based enhanced inter-cell interference coordination (eICIC) implementation.

Abstract At the start of the 21st century, wireless mobile communications has witnessed an unprecedented growth fueled by information explosion and technology revolution. After much fierce technology competitions and uncertainties, two third‐generation (3G) wideband standards have emerged to dominate the wireless mobile communications for years to come. They are the CDMA2000 [ 1 ] and the universal mobile terrestrial system (UMTS) [ 2 ] standards, both of which are based on code‐division multiple‐access (CDMA) technology. In this paper, we shall indicate how current 2G digital wireless systems might evolve into these 3G systems. We shall examine the likely innovative techniques to be adopted for further evolution of the two systems and the possible capacity gains obtainable by utilizing these techniques. Copyright © 2003 John Wiley & Sons, Ltd.

The optimal MAP detection algorithm for demodulation of M-QAM signaling in the frequency flat Rayleigh fading channel is proposed. A recursive structure is derived which allows for symbol-by-symbol metrics to be computed and data decisions to be made in an efficient manner. The complexity problem inherent to optimal detection schemes is addressed and approximations to optimal detection are considered which reduce complexity to practical levels yet still provide near-optimal performance levels. Reduced complexity algorithms are obtained through the use of decision feedback and thresholding which allow for higher order modulations such as 16-QAM to be implemented. Performance characterization of the algorithms presented are obtained via Monte Carlo simulation and results show that near-optimal bit error probability levels can be achieved. Extensions of the algorithms to include diversity combining techniques are also developed and shown to provide improved performance. Some theoretical derivations for optimal detection of 16-QAM in fading with diversity are also presented.>

The nonlinear digital carrier synchronization structure is a coherent demodulation technique that has many advantages for mobile communications. The nonlinear digital synchronizer is investigated in the presence of time varying fading for BPSK, QPSK, and pi /4-QPSK modulations. This paper addresses the design of optimal unconstrained smoothing filters for the nonlinear synchronizer structure. An approximate bit error probability analysis demonstrates that performance is quite near ideal and that no error floor exists in time varying fading.>