Performance analysis of multicell coordination in cellular wireless networks

Abstract

In this thesis, multicell coordination for wireless cellular networks is studied, whereby various approaches have been conducted to tackle this issue. Firstly, the coverage probability and e ective capacity in downlink multiple-input multiple-output (MIMO) cellular system are considered. Two scenarios are investigated; in the rst scenario, it is assumed that the system employs distance-based fractional power control with no multicell coordination. For the second scenario, it is assumed that the system implements multicell coordinated beamforming so as to cancel inter-cell interference. The base stations (BS) are modelled as randomly uniformly distributed in the area according to Poisson point process (PPP). Using tools from stochastic geometry, tractable, analytical expressions for coverage probability and e ective capacity are derived for both scenarios. Secondly, an adaptive strategy for inter-cell interference cancellation and coordination is proposed for downlink multicarrier cellular random networks. The adaptive strategy coordinates and cancels the interference on the both frequency and spatial domains. Based on this adaptive strategy, two interference management schemes have been proposed. The adaptation process is implemented based on measured instantaneous signal-to-interference and noise ratio (SINR) of the considered user. Furthermore, the locations of base stations BSs are modelled as an independent spatial PPP. Using tools from stochastic geometry, the proposed schemes have been analytically evaluated. Analytical expressions for coverage probability are derived for both schemes. In addition, an expression for average rate has been derived using the coverage probability analysis. Thirdly, low complexity algorithms for user scheduling have been proposed for coordinated MIMO multicell network. The algorithms consist of two stages: multicell scheduling stage and precoding stage. The algorithm works on sequential distributive manner. Two variants of multicell scheduling are proposed. The rst algorithm has less complexity but leads to more di erence in sum rate among cells. While the second algorithm results in better fairness in terms of system performance but causes frequent signalling among the cells. Moreover, the algorithm is extended to multimode selection in addition to the user selection. Finally, an adaptive coordination scheme for energy-effeicient resource allocation has been developed for orthogonal frequency division multiple access (OFDMA) cellular networks. The proposed scheme consists of centralised and distributed stages for allocating resources to cell-edge and cell-centre users, respectively. The optimisation problems are formulated as integer linear fractional and integer linear problems for the first stage and second stages, respectively. The spectral-energy trade-o is analysed under the constraint of fairness among users. In summary, the research work presented in this thesis reveals statistical approach to analyse the multicell coordination in random cellular networks. It also offers insight into the resource allocation and scheduling problems within multicell coordination framework, and how to solve them with a certain objective.