Multi-antenna and multi-carrier wireless transmission techniques are expected to provide high peak data rates and spectral efficiency, good coverage and reliable transmission required by emerging wireless standards such as 3GPP Long Term Evolution (LTE) and 3GPP LTE-Advanced. The multi-stream transmission via Multiple-Output Multiple-Input (MIMO) systems achieves different gains using beamforming, spatial diversity and spatial multiplexing techniques. The multi-carrier modulation via Orthogonal Frequency Division Multiplexing (OFDM) enhances spectral efficiency and facilitates using simple transceiver structures for broadband communications. MIMO-OFDM transmission impacts the design of many physical-level, system-level and radio resource management (RRM) functions as well as interaction between link and system level called Link-to-System (L2S) interface. In this thesis methods for optimizing L2S interface and RRM for MIMO-OFDM wireless systems and performance measures suitable for the system level performance evaluation are developed. The derived techniques are needed in network planning and optimization in order to analyze coverage, interference, frequency utilization, traffic loading. Moreover, they are used in dynamic system level simulations. In this thesis a computational efficient method for calculating the effective Signal-to-Interference-and-Noise-Ratio (SINR) mapping as advanced L2S interface for MIMO-OFDM transmission at the system-level is introduced. Asymptotic distribution of the effective SINR is established. In case of fast link adaptation with adaptive modulation and coding a mixture distribution model is used. The established distribution allows to utilize system capacity measure with a confidence and to evaluate the overall system performance. A measure for ergodic system capacity is established analytically through the mean value of the effective SINR. The proposed performance measure is attractive for the system level since it incorporates the L2S model used as a quality measure of a radio link. The simulation results carried out in specific mobility scenarios in 3GPP LTE downlink network verify the analytical results and show clear impact of mobility on the system capacity. In addition, fast and accurate rank adaptation method based on system level capacity is developed. It provides efficient and computationally simple procedure for adaptation to the varying channel conditions.
|Translated title of the contribution||Mobiilin langattoman MIMO-OFDM järjestelmän suorituskyvyn analyysia: Työkaluja ja tuloksia|
|Publication status||Published - 2012|
|MoE publication type||G5 Doctoral dissertation (article)|
- performance analysis
- Link-to-System interface
- effective SINR