Self-Organized Intelligent Distributed Antenna System in LTE

In order to reduce the operational expenditure, while optimizing network efficiency and service quality, self-organizing network is introduced in long term evolution. The SON includes several functions, e.g. self-establishment of new base stations, load balancing, inter-cell interference coordination. Load balancing and inter-cell interference coordination are two of the most important self-organizing functions. In this thesis, load-balancing solution is investigated in order to optimize quality of service. To enable load balancing among distributed antenna modules, we dynamically allocate the remote antenna modules to the BTS sectors. Self-optimizing intelligent distributed antenna system is formulated as an optimization problem. Three evolutionary algorithms are proposed for optimization: genetic algorithm, estimation distribution algorithm, and particle swarm optimization. Computational results of different traffic scenarios after performing the algorithms, demonstrate that the the algorithms attain excellent key performance indicators. The downlink performance of cellular networks is known to be strongly limited by inter-cell interference in multi-carrier based systems when full frequency reuse is utilized. In order to mitigate this interference, a number of techniques have recently been proposed, e.g., the soft frequency reuse scheme. In this thesis, DAS is utilized to implement SFR. The central concept of this architecture is to distribute the antennas in a hexagonal cell such that the central antenna transmits the signal using entire frequency band while the remaining antennas utilize only a subset of the frequency bands based on a frequency reuse factor. A throughput-balancing scheme for DAS-SFR that optimizes cellular performance according to the geographic traffic distribution is also investigated in order to provide a high QoS. To enable throughput balancing among antenna modules, we dynamically change the antenna module's carrier power to manage the inter-cell interference. A downlink power self-optimization algorithm is proposed for the DAS-SFR system. The transmit powers are optimized in order to maximize the spectral efficiency of a DAS-SFR and maximize the number of satisfied users under different users' distributions. The results show that proposed algorithm is able to guarantee a high QoS that concentrates on the number of satisfied users as well as the capacity of satisfied users as the two KPIs.