Distributed Optimization of Multi-Cell Uplink Co-operation with Backhaul Constraints

We address the problem of uplink co-operative reception with constraints on both backhaul bandwidth and the receiver aperture, or number of antenna signals that can be processed. The problem is cast as a network utility (weighted sum rate) maximization subject to computational complexity and architectural bandwidth sharing constraints. We show that a relaxed version of the problem is convex, and can be solved via a dual-decomposition. The proposed solution is distributed in that each cell broadcasts a set of {\em demand prices} based on the data sharing requests they receive. Given the demand prices, the algorithm determines an antenna/cell ordering and antenna-selection for each scheduled user in a cell. This algorithm, referred to as {\em LiquidMAAS}, iterates between the preceding two steps. Simulations of realistic network scenarios show that the algorithm exhibits fast convergence even for systems with large number of cells.Comment: IEEE ICC Conference, 201

Wireless Performance Evaluation of Building Layouts: Closed-Form Computation of Figures of Merit

This paper presents a part of our ground-breaking work on evaluation of buildings in terms of wireless friendliness in the building-design stage. The main goal is to devise construction practices that provide for a good performance of wireless networks deployed in buildings. In this paper, the interference gain (IG) and power gain (PG) are defined as two figures of merit (FoM) of the wireless performance of buildings. The FoMs bridge the gap between building design and wireless communications industries. An approach to derive exact closed-form equations for these FoMs is proposed for the first time. The derived analytic expressions facilitate straightforward and more computationally efficient numerical evaluation of the proposed FoMs as compared to Monte Carlo simulations for well-known indoor propagation models. It is shown that the derived closed-form expression can be readily employed to evaluate the impact of building properties, such as the sizes and the aspect ratios (ARs) of rooms, on the wireless performance. The proposed approach sheds light to architects on evaluation and design of wireless-friendly building layouts

Exploiting the ability of Self Organizing Networks for inter-cell interference coordination for emergency communications in cellular networks

Title from PDF of title page, viewed on June 15, 2015Thesis advisor: Cory BeardVitaIncludes bibliographic references (pages 56-57)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2014In the current scenario, radio planning of wireless cellular networks and analysis of radio performance should be agile because it is expected that in the near future we will be reaching to the point where there will be as many mobile devices as people in the world. So, there should be a rapid revolution in technology which can aid in the management of resources and maximization of throughput to satisfy users effectively. LTE and LTE-Advanced is designed to meet high bit rate service requirements; however, the initial challenge of the wireless channel, such as limited spectrum, leads to frequency reuse but also irrevocable interference. This thesis gives a holistic conspectus of interference coordination in LTE cellular systems utilizing the ability of Self Organizing Networks (SON). LTE uses a universal frequency reuse concept and the only interference observed in LTE is inter-cell interference. In a network where users are randomly distributed over three cells, it manages resources between the base stations by restricting some resource blocks for Cell Edge Users (CEU) of the neighboring cell and other resource blocks for Cell Center Users (CCU). This is done in a semi-static approach by taking into account the location of the user and varying channel conditions. Cell edge users and cell center users are distinguished based upon the SINR level. The management of the resources are regulated as per the user requirements and coordinated by the neighboring cells. The results have been simulated in two different ambiances viz., normal traffic and the emergency condition to show its performance in exigency. The throughput of the CCUs and CEUs in normal traffic has been compared. Also, the approach and results are shown to be highly reliable.Introduction -- Background -- Our work -- MATLAB code implementation -- Results and analysis -- Conclusion and future scop

Practical large-scale coordinated scheduling in LTE-Advanced networks

In LTE-Advanced, the same spectrum can be re-used in neighboring cells, hence coordinated scheduling is employed to improve the overall network performance (cell throughput, fairness, and energy efficiency) by reducing inter-cell interference. In this paper, we advocate that large-scale coordination can be obtained through a layered solution: a cluster of few (i.e., three) cells is coordinated at the first level, and clusters of coordinated cells are then coordinated at a larger scale (e.g., tens of cells). We model both small-scale coordination and large-scale coordination as optimization problems, show that solving them at optimality is prohibitive, and propose two efficient heuristics that achieve good results, and yet are simple enough to be run at every Transmission Time Interval (TTI). Detailed packet-level simulations show that our layered approach outperforms the existing ones, both static and dynamic

Mutual Successive Interference Cancellation Strategies in NOMA for Enhancing the Spectral Efficiency of CoMP Systems

International audienceThe densification of mobile networks should enable the fifth generation (5G) mobile networks to cope with the ever increasing demand for higher rate traffic, reduced latency, and improved reliability. The large scale deployment of small cells and distributed antenna systems in heterogeneous environments will require more elaborate interference mitigating techniques to increase spectral efficiency and to help unlock the expected performance leaps from the new network topologies. Coordinated multi-point (CoMP) is the most advanced framework for interference management enabling the cooperation between base stations to mitigate inter-cell interference and boost cell-edge user performance. In this paper, we study the combination of CoMP with mutual SIC, an interference cancellation technique based on power-domain non-orthogonal multiple access (NOMA) that enables multiplexed users to simultaneously cancel their corresponding interfering signals. A highly efficient inter-cell interference cancellation scheme is then devised, that can encompass several deployment configurations and coordination techniques. The obtained results prove the superiority of this approach compared to conventional NOMA-CoMP systems

User Association and Resource Allocation Optimization in LTE Cellular Networks

International audienceAs the demand for higher data rates is growing exponentially, homogeneous cellular networks have been facing limitations when handling data traffic. These limitations are related to the available spectrum and the capacity of the network. Heterogeneous Networks (HetNets), composed of Macro Cells (MCs) and Small Cells (SCs), are seen as the key solution to improve spectral efficiency per unit area and to eliminate coverage holes. Due to the large imbalance in transmit power between MCs and SCs in HetNets, intelligent User Association (UA) is required to perform load balancing and to favor some SCs attraction against MCs. As Long Term Evolution (LTE) cellular networks use the same frequency sub-bands, User Equipments (UEs) may experience strong Inter-Cell Interference (ICI), especially at cell edge. Therefore, there is a need to coordinate the Resource Allocation (RA) among the cells and to minimize the ICI. In this paper, we propose a generic algorithm to optimize user Association and resource allocation in LTE networks. Our solution, based on game theory, permits to compute Cell Individual Offset (CIO) and a pattern of power transmission over frequency and time domain for each cell. Simulation results show significant benefits in the average throughput and also cell edge user throughput of 40% and 55% gains respectively. Furthermore, we also obtain a meaningful improvement in energy efficiency